Transport critical current densities and n factors in mono- and multifilamentary MgB2Fe tap

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TPO52阅读原文+译文+答案

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TPO阅读52 溪流沉淀Stream DepositA large, swift stream or river can carry all sizes of particles, from clayto boulders. When the current slows down, its competence (how much it can carry)decreases and the stream deposits the largest particles in the streambed. Ifcurrent velocity continues to decrease - as a flood wanes, for example - finerparticles settle out on top of the large ones. Thus, a stream sorts itssedimentaccording to size. A waning flood might deposit a layer of gravel,overlain by sand and finally topped by silt and clay. Streams also sort sedimentin the downstream direction. Many mountain streams are choked with boulders andcobbles, but far downstream, their deltas are composed mainly of fine silt andclay. This downstream sorting is curious because stream velocity generallyincreases in the downstream direction. Competence increases with velocity, so ariver should be able to transport larger particles than its tributaries carry.One explanation for downstream sorting is that abrasion wears away the bouldersand cobbles to sand and silt as the sediment moves downstream over the years.Thus, only the fine sediment reaches the lower parts of most rivers.A stream deposits its sediment in three environments: Alluvial fans anddeltas form where stream gradient (angle of incline) suddenly decreases as astream enters a flat plain, a lake, or the sea; floodplain deposits accumulateon a floodplain adjacent to the stream channel; and channel deposits form in thestream channel itself. Bars, which are elongated mounds of sediment, aretransient features that form in the stream channel and on the banks. They commonly form in one year and erode the next. Rivers used for commercial navigation must be recharged frequently because bars shift from year toyear.Imagine a winding stream. The water on the outside of the curve moves faster than the water on the inside. The stream erodes its outside bank because the current's inertia drives it into the outside bank. At the same time, the slower water on the inside point of the bend deposits sediment, forming a point bar. A mid-channel bar is a sandy and gravelly deposit that forms in the middle of a stream channel.Most streams flow in a single channel. In contrast, a braided stream flowsin many shallow, interconnecting channels. A braided stream forms where more sediment is supplied to a stream than it can carry. The stream dumps the excesssediment, forming mid-channel bars. The bars gradually fill a channel, forcing the stream to overflow its banks and erode new channels. As a result, a braided stream flows simultaneously in several channels and shifts back and forth across its floodplain. Braided streams are common in both deserts and glacial environments because both produce abundant sediment. A desert yields large amounts of sediment because it has little or no vegetation to prevent erosion. Glaciers grind bedrock into fine sediment, which is carried by streams flowing from the melting ice. If a steep mountain stream flows onto a flat plain, its gradient and velocity decrease sharply. As a result, it deposits most of its sediment in a fan-shaped mound called an alluvial fan. Alluvial fans are common in many arid and semiarid mountainous regions.A stream also slows abruptly where it enters the still water of a lake orocean.The sediment settles out to form a nearly flat landform called a delta.Part of the delta lies above water level, and the remainder lies slightly belowwater level. Deltas are commonly fan-shaped, resembling the Greek letter "delta" . Both deltas and alluvial fans change rapidly. Sediment fills channels(waterways), which are then abandoned while new channels develop as in a braided stream.As a result, a stream feeding a delta or fan splits into many channels called distributaries. A large delta may spread out in this manner until it covers thousands of square kilometers. Most fans, however, are much smaller, covering a fraction of a square kilometer to a few square kilometers. TheMississippi River has flowed through seven different delta channels during the past 5,000 to 6,000 years. But in recent years, engineers have built greatsystems of levees (retaining walls) in attempts to stabilize the channels.索取“TPO52阅读题目+答案+解析”，请加sunny老师微信(shnc2014)，发送暗号“TPO52”TPO阅读52 纳图夫文化Natufian CultureIn the archaeological record of the Natufian period, from about 12,500 to10,200 years ago, in the part of the Middle East known as the Levant - roughly east of the Mediterranean and north of the Arabian Peninsula - we see clear evidence of agricultural origins. The stone tools of the Natufians included many sickle-shaped cutting blades that show a pattern of wear characteristic ofcerealharvesting. Also, querns (hand mills) and other stone tools used forprocessing grain occur in abundance at Natufian sites, and many such tools show signs of long, intensive use. Along with the sickle blades are many grinding stones, primarily mortars and pestles of limestone or basalt. There is alsoevidence that these heavy grinding stones were transported over long distances, more than 30 kilometers in some cases, and this is not something known to have been done by people of preceding periods. Fishhooks and weights for sinking fishing nets attest to the growing importance of fish in the diet in some areas. Stone vessels indicate an increased need for containers, but there is no evidence of Natufian clay working or pottery. Studies of the teeth of Natufians also strongly suggest that these people specialized in collecting cereals and may have been cultivating them and in the process of domesticating them, but they were also still hunter-foragers who intensively hunted gazelle and deer in more lush areas and wild goats and equids in more arid zones.The Natufians had a different settlement pattern from that of their predecessors. Some of their base camps were far larger (over 1,000 square meters) than any of those belonging to earlier periods, and they may have lived in some of these camps for half the year or even more. In some of the camps, people made foundations and other architectural elements out of limestone blocks. Trade in shell, obsidian, and other commodities seems to have been on the rise, and anthropologists suspect that the exchange of perishables (such as skins, foodstuffs) and salt was also on the increase. With the growing importance of wild cereals in the diet, salt probably became for the first time a near necessity: people who eat a lot of meat get many essential salts from this diet, but diets based on cereals can be deficient in salts. Salt was probably also important as a food preservative in early villages.As always, there is more to a major cultural change than simply a shift ineconomics. The Natufians made (and presumably wore) beads and pendants in manymaterials, including gemstones and marine shells that had to be imported, and it is possible that this ornamentation actually reflects a growing sense of ethnic identity and perhaps some differences in personal and group status. Cleverly carved figurines of animals, women, and other subjects occur in many sites, andNatufian period cave paintings have been found in Anatolia, Syria, and Iran. More than 400 Natufian burials have been found, most of them simple gravesset in house floors. As archaeologist Belfer-Cohen notes, these burials may reflect an ancestor cult and a growing sense of community emotional ties and attachment to a particular place, and toward the end of the Natufian period, people in this area were making a strict separation between living quarters and burial grounds. In contrast with the Pleistocene cultures of the Levant,Natufian culture appears to have experienced considerable social change.The question of why the Natufians differed from their predecessors in these and other ways and why they made these first steps toward farming as a way of life remains unclear. There were climate changes, of course, and growing aridity and rising population densities may have forced them to intensifytheexploitation of cereals, which in turn might have stimulated the development of sickles and other tools and the permanent communities that makeagricultureefficient. But precisely how these factors interacted with others at play is poorly understood.TPO52 撒哈拉以南非洲早期食品生产Early Food Production In Sub-Saharan AfricaAt the end of the Pleistocene (around 10,000 B.C.), the technologies offood production may have already been employed on the fringes of the rain forests of western and central Africa, where the common use of such root plants as the African yam led people to recognize the advantages of growing their own food. The yam can easily be resprouted if the top is replanted. This primitive form of "vegeculture" (cultivation of root and tree crops) may have been the economic tradition onto which the cultivation of summer rainfall cereal crops was grafted as it came into use south of the grassland areas on the Sahara's southern borders.As the Sahara dried up after 5000 B.C., pastoral peoples (cattle herders) moved southward along major watercourses into the savanna belt of West Africa and the Sudan. By 3000 B.C., just as ancient Egyptian civilization was coming into being along the Nile, they had settled in the heart of the East African highlands far to the south. The East African highlands are ideal cattle country and the home today of such famous cattle-herding peoples as the Masai. The highlands were inhabited by hunter-gatherers living around mountains near the plains until about 3300 B.C., when the first cattle herders appeared. These cattle people may have moved between fixed settlements during the wet and dry seasons, living off hunting in the dry months and their own livestock and agriculture during the rains.As was the case elsewhere, cattle were demanding animals in Africa. They required water at least every 24 hours and large tracts of grazing grass if herds of any size were to be maintained. The secret was the careful selection of grazing land, especially in environments where seasonal rainfall led to marked differences in graze quality throughout the year. Even modest cattle herdsrequired plenty of land and considerable mobility. To acquire such land often required moving herds considerable distances, even from summer to winter pastures. At the same time, the cattle owners had to graze their stock in tsetse-fly-free areas The only protection against human and animal sleeping sickness, a disease carried by the tsetse fly, was to avoid settling or farming such areas - a constraint severely limiting the movements of cattle-owning farmers in eastern and central Africa. As a result, small cattle herds spread south rapidly in areas where they could be grazed. Long before cereal agriculture took hold far south of the Sahara, some hunter-gatherer groups in the savanna woodlands of eastern and southern Africa may have acquired cattle, and perhaps other domesticated animals, by gift exchange or through raids on herding neighbors.Contrary to popular belief: there is no such phenomenon as "pure" pastoralists, a society that subsists on its herds alone. The Saharan herders who moved southward to escape drought were almost certainly also cultivating sorghum, millet; and other tropical rainfall crops. By 1500 B.C., cereal agriculture was widespread throughout the savanna belt south of the Sahara. Small farming communities dotted the grasslands and forest margins of eastern West Africa, all of them depending on what is called shifting agriculture. This form of agriculture involved clearing woodland, burning the felled brush over the cleared plot, mixing the ash into the soil, and then cultivating the prepared fields. After a few years, the soil was exhausted, so the farmer moved on, exploiting new woodland and leaving the abandoned fields to lie fallow.Shifting agriculture, often called slash-and-burn, was highly adaptive for savanna farmers without plows, for it allowed cereal farming with the minimal expenditure of energy.The process of clearance and burning may have seemed haphazard to the uninformed eye, but it was not. Except in favored areas, such as regularly inundated floodplains: tropical Africa's soils were of only moderate to lowfertility. The art of farming was careful soil selection, that is, knowing which soils were light and easily cultivable, could be readily turned with small hoes, and would maintain their fertility over several years' planting, for cereal crops rapidly remove nitrogen and other nutrients from the soil. Once it had taken hold: slash-and-burn agriculture expanded its frontiers rapidly as village after village took up new lands, moving forward so rapidly that one expert has estimated it took a mere two centuries to cover 2,000 kilometers from eastern to southern Africa.托福TPO52听力文本+音频下载+答案托福TPO52(综合+独立)写作范文及音频下载托福TPO1-51 听、说、读、写大全，请点击：/toefltpo/index.html 上海学托福，给你高能高分!。

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Light trapping in ultrathin plasmonic solar cells Vivian E. Ferry,1,2,* Marc A. Verschuuren,3 Hongbo B. T. Li,4 Ewold Verhagen,1 Robert J. Walters,1 Ruud E. I. Schropp,4 Harry A. Atwater,2 and Albert Polman11Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands2Thomas J. Watson Laboratories of Applied Physics,California Institute of Technology, Pasadena, California 91125 USA3Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands4Debye Institute for N anomaterials Science, Section Nanophotonics,Utrecht University, P. O. Box 80.000, 3508 TA Utrecht, The N etherlands*vivianf@Abstract: We report on the design, fabrication, and measurement ofultrathin film a-Si:H solar cells with nanostructured plasmonic backcontacts, which demonstrate enhanced short circuit current densitiescompared to cells having flat or randomly textured back contacts. Theprimary photocurrent enhancement occurs in the spectral range from 550nm to 800 nm. We use angle-resolved photocurrent spectroscopy to confirmthat the enhanced absorption is due to coupling to guided modes supportedby the cell. Full-field electromagnetic simulation of the absorption in theactive a-Si:H layer agrees well with the experimental results. Furthermore,the nanopatterns were fabricated via an inexpensive, scalable, and precise nanopatterning method. These results should guide design of optimized,non-random nanostructured back reflectors for thin film solar cells.©2010 Optical Society of AmericaOCIS codes: (250.5403) Plasmonics; (350.6050) Solar Energy.References and links1. A. Shah, P. Torres, R. Tscharner, N. Wyrsch, and H. Keppner, “Photovoltaic technology: the case for thin-film solar cells,” Science 285(5428), 692–698 (1999).2. R. H. Franken, R. L. Stolk, H. Li, C. H. M. van der Werf, J. K. Rath, and R. E. I. Schropp, “Understanding light trapping by lig ht scattering textured back electrodes in thin film n-i-p-type silicon solar cells,” J. Appl. Phys.102(1), 014503 (2007).3. J. Müller, B. Rech, J. Springer, and M. Vanecek, “TC O and light trapping in silicon thin film solar cells,” Sol. Energy 77(6), 917–930 (2004).4. R. E. I. Schropp, and M. Zeman, Amorphous and microcrystalline silicon solar cells: modeling, materials, and device technology, (Kluwer Academic Publishers, Norwell, Mass., 1998).5. P. Campbell, and M. A. Green, “The limiting efficiency of silicon solar-cells under concentrated s unlight,” IEEE Trans. Electron. Dev. 33(2), 234–239 (1986).6. D. L. S taebler, and C. R. Wronski, “Reversible conductivity changes in discharge-produced amorphous silicon,”Appl. Phys. Lett. 31(4), 292–294 (1977).7. A. V. Shah, H. Schade, M. Vanecek, J. Meier, E. Vallat-Sauvain, N. Wyrsch, U. Kroll, C. Droz, and J. Bailat, “Thin-film Silicon Solar Cell Technolog y,” Prog. Photovolt. Res. Appl. 12(23), 113–142 (2004).8. P. Lechner, W. Frammelsberger, W. Psyk, R. Geyer, H. Mau rus, D. Lu ndszien, H. Watner, an d B. Eichhorn, “Status of performance of thin film silicon solar cells and modules,” C onference record of the 23rd European Photovoltaic Solar Energy Conference, 2023–2026 (2008).9. E. Yablonovitch, and G. D. Cod y, “Intensity enhancement in textured optical sheets for solar cells,” IEEE Trans.Electron. Dev. 29(2), 300–305 (1982).10. Ü. Dagkaldiran, A. Gordijn, F. Finger, H. M. Yates, P. Evans, D. W. Sheel, Z. Remes, and M. Vanecek,“Amorphous silicon solar cells made with SnO2:F TCO films deposited by atmospheric pressure CVD,” Mater.Sci. Eng. B 159–160, 6–9 (2009).11. J. Krč, F. Smole, and M. Topič, “Potential of light trapping in microcrystalline silicon solar cells with textured substrates,” Prog. Photovolt. R es. Appl. 11(7), 429–436 (2003).12. S. F ahr, C. R ockstuhl, and F. Lederer, “Engineering the randomness for enhanced absorption in solar cells,”Appl. Phys. Lett. 92(17), 171114 (2008).13. H. A. Atwater, and A. Polman, “Plasmonics for improved photovoltaic devices,” Nat. Mater. 9(3), 205–213(2010).14. V. E. Ferry, J. N. Munday, and H. A. Atwater, “Design considerations for plasmonic photovoltaics,” Ad v. Mater.(to be published).#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010(C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A23715. H. R. S tuart, and D. G. Hall, “Island size effects in nanoparticle-enhanced photodetectors,” Appl. Phys. Lett.73(26), 3815–3817 (1998).16. S. Pillai, K. R. C atchpole, T. Trupke, and M. A. Gre en, “Surface plasmon enhanced silicon solar cells,” J. Appl.Phys. 101(9), 093105 (2007).17. K. R. C atchpole, and A. Polman, “Design principles for particle plasmon enhanced solar cells,” Appl. Phys. Lett.93(19), 191113 (2008).18. F. J. Beck, A. Polman, and K. R. C atchpole, “Tu nable light trapping for solar cells using localized surfaceplasmons,” J. Appl. Phys. 105(11), 114310 (2009).19. D. Derkacs, S. H. Lim, P. Matheu, W. Mar, and E. T. Yu, “Improved performance of amorphous silicon solarcells via s cattering from surface plasmon polaritons in nearby metallic nanoparticles,” Appl. Phys. Lett. 89(9),093103 (2006).20. P. Matheu, S. H. Lim, D. Derkacs, C. McPheeters, and E. T. Yu, “Metal and dielectric nanoparticle scattering forimproved optical absor ption in photovoltaic devices,” Appl. Phys. Lett. 93(11), 113108 (2008).21. K. Nakayama, K. Tanabe, and H. A. Atwater, “Plasmonic nanoparticle enhanced lig ht absorption in GaAs solarcells,” Appl. Phys. Lett. 93(12), 121904 (2008).22. I. M. Pryce, D. D. Koleske, A. J. Fischer, and H. A. Atwater, “Plasmonic nanoparticle enhanced photocurrent inGaN/InGaN/GaN quantu m well solar cells,” Appl. Phys. Lett. 96(15), 153501 (2010).23. V. E. Ferry, L. A. Sweatlock, D. Pacifici, and H. A. Atwater, “Plasmonic nanos tructure desig n for efficient lightcoupling into solar cells,” Nano Lett. 8(12), 4391–4397 (2008).24. P. N. Saeta, V. E. Ferry, D. Pacifici, J. N. Munday, and H. A. Atwater, “How much can guided modes enhanceabsorption in thin solar cells?” Opt. Express17(23), 20975–20990 (2009).25. J. Zhu, C.-M. Hsu, Z. Yu, S. Fan, and Y. Cui, “Nanodome solar cells with efficient light management and selfcleaning,”Nano Lett. 10(6), 1979–1984 (2010).26. A. Lin, and J. Phillips, “Optimization of rand om diffraction gratings in thin-film solar cells using geneticalgorithms,” Sol. Energy Mater. Sol. Cells 92(12), 1689–1696 (2008).27. O. Isabella, A. C ampa, M. C. R. Heijna, W. Soppa, R. van Ervan, R. H. Franken, H. Borg, and M. Zeman,“Diffraction gratings for light t rapping in thin-film silicon solar cells,” Conference Record of the 23rd Eu ropeanPhotovoltaic Solar Energy Conference, 2320–2324 (2008).28. C. Eisele, C. E. Nebel, and M. Stu tzmann, “Periodic lig ht coupler gratings in amorphous thin film solar cells,” J.Appl. Phys. 89(12), 7722–7726 (2001).29. C. Haase, and H. Stiebig, “Thin-film silicon solar cells with efficient periodic lig ht trapping texture,” Appl. Phys.Lett. 91(6), 061116 (2007).30. K. Sato, Y. Gotoh, Y. Wakayama, Y. Hayasahi, K. Adachi, and H. Nishimura, “Highly textured SnO2:F TC Ofilms for a-Si solar cells,” R ep. Res. Lab. Asahi Glass Co. Ltd. 42, 129–137 (1992).31. V. E. Ferry, M. A. Verschuuren, H. B. T. Li, R. E. I. Schropp, H. A. Atwater, and A. Polman, “Improved redresponsein thin film a-Si:H solar cells with soft-imprinted plasmonic back reflectors,” Appl. Phys. Lett. 95(18),183503 (2009).32. C. Stuart, and Y. Chen, “R oll in and roll ou t: a path to hig h-throughput nanoimprint lithography,” ACS Nano3(8), 2062–2064 (2009).33. M. Versc huuren and H. van Sprang, “3D photonic structures by sol-gel imprint lithography,” Mater. R es. Soc.Sym. Proc. 1002, N03–N05 (2007).34. T. W. Odom, J. C. Love, D. B. Wolfe, K. E. Paul, and G. M. Whitesides, “Improved pattern transfer in softlithog raphy u sing composite stamps,” Lang muir 18(13), 5314–5320 (2002).35. A. D. Rakic, A. B. Djurisic, J. M. Elazar, and M. L. Majewski, “Optical properties of metallic films for verticalcavity optoelectronic devices,” Appl. Opt. 37(22), 5271–5283 (1998).36. H. B. T. Li, C. H. M. van der Werf, J. K. Rath, and R. E. I. Schropp, “Hot wire CVD deposition ofnanocrystalline silicon solar cells on rough substrates,” Thin Solid Films 517(12), 3476–3480 (2009).1. IntroductionThin-film solar cells offer the benefits of reduced materials and fabrication costs as well as the advantages of light-weight, flexible devices [1]. For these geometries to exhibit efficientcurrent generation, light trapping schemes are essential to capture the red and near-infraredportion of the solar spectrum [2,3]. Here we demonstrate a hydrogenated amorphous Si (a-Si:H) solar cell with plasmonic light trapping structures built into the metallic back contact.The nanopatterns allow ultrathin a-Si:H cells (160 nm) with short circuit current dens itiesexceeding that of similar cells with randomly-textured back contacts due to near-fieldcoupling to guided modes supported by the multi–layer solar cell structure. The nanopatternsare fabricated via an inexpensive and scalable imprinting technique that could be adopted into standard solar cell production. We use a-Si:H as a test platform for photonic nanopatterndesign, but our approach is broadly applicable to other thin-film solar cell material systems.Thin film solar cells made from a-Si:H are attractive candidates for large-scalephotovoltaic applications because Si is highly abundant and can be deposited on flexiblesubstrates using processes that are compatible with roll-to-roll processing [4]. Since minority#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A238carrier diffusion lengths are very short in a-Si:H, the cells are often made with a p-i-n or n-i-p structure where the intrinsic absorbing layer is hundreds of nanometers thick and carriertransport is dominated by drift. Ultrathin film cells, where the thickness of the absorber layeris significantly reduced, offer further cost and performance advantages. An ultrathin filmabsorbing layer exhibits decreased bulk recombination, which can lead to a higher opencircuit voltage (V oc), since V oc increases with decreasing dark current I dark as V oc =(kT/q)ln(I photo/I dark + 1) [5]. A final important benefit of this ultrathin film design for a-Si:H isthe reduction of the well-known Staebler-Wronski degradation effect [6] that has limited thelong-term performance of a-Si:H photovoltaics so far. Ultrathin n-i-p devices, withthicknesses such as we discuss here, possess high internal electric fields, which are known toexhibit no or only minimal light-induced degradation [4,7,8].However, the use of thin absorbing layers reduces the short-circuit current density (J sc) dueto the decreased optical path length in the semiconductor. Strategies for increasing J scgenerally involve the incorporation of surface texturing to scatter incident light into offnormal angles. In thick, wafer-based photovoltaic cells, such surface texturing can lead to amaximum intensity enhancement of 4n2 at wavelengths near the band edge, where n is theindex of refraction of the semiconductor [9]. For thin and ultrathin film cells where the totaldevice thickness may be less than a wavelength, light trapping is frequently accomplishedthrough the use of randomly roughened layers, either on the front or rear of the cell [10–12]. Recently, it has been proposed that the incorporation of plasmonic metal nanostructures inthin film solar cells could lead to strong light trapping because strong light-matter interactionin plas monic nanostructures enables large scattering cross sections [13,14]. Many of theseplasmonic photovoltaic designs incorporate metal nanoparticles on the front surface of thecell. This can lead to preferential scattering of the incident light into the semiconductor overan increased angular range, thereby enhancing the optical path length [15–22]. While strong enhancements of photocurrent have been reported in such solar cells for near-bandedge light,these are often offset by a reduced photocurrent in the blue part of the solar spectrum due to destructive Fano interference [18,21]. An alternative strategy is to build the scattering nanostructures directly into the back contact of the device. In this geometry, the incident bluelight is directly absorbed and does not interact with the back contact scatterers, while the redlight that is poorly absorbed in a single pass through the cell is strongly scattered [Fig. 1(a)][23–25]. In our design, these back scatterers are designed to couple incident light into guidedmodes supported by the cell with high intensity in the absorbing semiconductor layer,dramatically reducing the thickness requirements by redirecting the absorption path into theplane of the solar cell. As opposed to cells with purely grating-based reflectors [26–29] or nanostructure designs to couple specifically to surface plasmon polariton modes [23], thedesign presented here takes advantage of the high scattering cross sections of plasmonic nanostructures to couple to waveguide modes.To date most theoretical and experimental studies of plasmonic light trapping structuresreference the enhanced absorption and photocurrent relative to an identical device without nanostructures (i.e., a planar back surface). While this reference is useful for understandingthe role of the scatterers, most realistic solar cells already employ some form of light trapping structures to enhance absorption. For a-Si:H, much work has been devoted to the design ofrandomly textured layers for increased absorption [2–4,10–12], and we compare ourplasmonic nanostructure designs to a commercial standard with known roughness andtopography, Asahi U-type glass [30]. Provided that the plasmonic nanostructures are welldesigned over the scale of a wavelength, we show here that the absorption enhancements canexceed those from random surface topography.#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A239Fig. 1. Plasmonic light trapping solar cell design. (a) Schematic cross section of the patternedsolar cell. Patterns are made on the rear glass substrate, and there is conformal deposition of alllayers over the patterns through the top ITO contact. Incident blue and red arrows indicate thatblue light is absorbed before reaching the back contact while red light interacts more with theback patterns. (b) Photograph of finished imprinted patterned solar cell substrate. Each coloredsquare is a separate device, with different particle diameter and pitch. (c) SEM of Agovercoated patterns showing 290 nm diameter particles with 500 nm pitch. (d) SEM image of across section of a fabricated cell, cut using focused ion beam milling. Note that the ultrat hin a-Si:H layer constitu tes only a small part of the cell.2. MethodsA significant challenge to the incorporation of plasmonic nanostructures in photovoltaics is fabrication: the feature sizes are typically tens to hundreds of nanometers, while photovoltaiccell dimensions may be in the m2 range. Techniques for large area metal nanostructureformation include island annealing, which produces irregular shapes and spacings [15,16],colloidal particles [19,20], which control the shape but not the spacing, and depositionthrough alumina templates, which can provide some control over the patterns [21,22]. Smallertest devices may use electron-beam lithography or focused ion beam patterning, which allowfor complete control but are too expensive for use in practical devices. In this work, we have fabricated cm2-scale a-Si:H solar cells using soft nanoimprint lithography [31] to incorporate plasmonic nanostructures in the Ag/ZnO:Al back contact of the cell [Fig. 1(b)]. Thistechnique offers the capability to form large-area nanopatterns with precise control over boththe dimensions and the spacing of the plasmonic scattering structures, and is amenable to rollto-roll processing [32]. In our case, the patterns are printed into a sol-gel silica layer usingsubstrate conformal imprint lithography (SCIL) [33], which is then overcoated with Ag and#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A240Fig. 2. Surface topography of nanopatterned and randomly textured solar cells. Tapping-modeAFM images of the top ITO contacts for two of the cells compared in this study. Theunderlying Ag/ZnO:Al nanostructure is transferred through each layer conformally, so thatboth the front and back contacts are structured. (a) Patterned cell with 500 nm pitch, (b) Cell onrand omly textu red Asahi U-type glass substrate.ZnO:Al to form the back contact [Fig. 1(c)]. A single substrate containing solar cells with nanopatterns of varying diameter and pitch as well as reference cells with flat back contacts isused to avoid variations between different deposition runs when comparing cell performance,shown in Fig. 1(b).The master substrate of nanopatterns was made using electron beam lithography on a Siwafer. A bilayer stamp was molded from the master, consisting of a thin high-modulus polydimethylsiloxane (PDMS) layer holding the nanopatterns and a low-modulus PDMS layerto bond the rubber to a 200 μm thick glass support for in-plane stiffness [34]. The stamp wasused to emboss a 100 nm thick layer of silica sol-gel on AF45 glass substrates using SCIL.The sol-gel layer solidified at room temperature by forming a silica network, while reactionproducts diffuse into the rubber stamp. After stamp release the sol-gel was post cured at 200°C. The patterned area was 10 cm by 4 cm, with patterned and flat reference cells tiled in 6mm x 6 mm sections. The sol-gel patterns together with the Asahi U-type glass wereovercoated with Ag and ZnO:Al via sputtering, and 13.56 MHz plasma enhanced chemicalvapor deposition was used to deposit the n-i-p a-Si:H layers. An array of 4 × 4 mm2squares ofITO was sputtered through a contact mask, and finger contacts were evaporated over the ITOusing a second contact mask. The final cell area of each device was 0.13 cm2. Device characterization was performed using a solar simulator under one sun illumination (AM1.5,100 mW/cm2) and EQE measurements were performed using monochromatic light from aXenon lamp with one sun light bias applied. Angle-resolved EQE measurements wereperformed using a supercontinuum laser source in combination with a monochromator with a passband of ~3 nm and a sample stage providing eucentric rotation about the point o fillumination. The illumination was focused to a spot diameter of approximately 500 μm at low numerical aperture. Finite-difference time domain simulations (FDTD) were performed using commercially available software. The layer thicknesses were taken from cell cross sections[such as Fig. 1(d)]. The optical constants of the ITO and ZnO:Al were taken as 2.08 + 0.004iand 1.93 + 0.004i, respectively, with slight dispersion measured using ellipsometry. Theoptical data for a-Si:H was taken from measured values. Ag was modeled using a Lorentz-Drude model fit to Palik data [35]. The simulation geometry for the randomly textured cellswas taken from measured AFM data, and used to construct the surface.Multiple copies of each cell design and reference are distributed over the substrate toreduce the possible effects of wafer-scale spatial inhomogeneity, and several cells of eachpattern were measured. Two different intrinsic layer thicknesses, corresponding to total a-Si:H thicknesses (including the n- and p-doped layers) of 340 nm and 160 nm were deposited on#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A241Fig. 3. Electrical measurements on plasmonic solar cells. Data are shown for a-Si:H with twodifferent intrinsic layer thicknesses. (a) a-Si:H thickness 340 nm and (b) a-Si:H thickness 160nm. Curves are shown for square grid patterns of 250 nm diameter plasmonic scatterers atpitches of 500 nm and 700 nm, the flat reference cell, and (in (b)) the randomly textured Asahicell.two substrates with identically prepared back contact patterns. Figure 1(d) shows a crosssection scanning electron microscopy (SEM) image of a fully fabricated nanopatterned cellhaving ana-Si:H thickness of 160 nm. The individual layers are clearly resolved. The ultrathina-Si:H layer is conformal to the nanopatterned contacts, with no cracks or voids observed inthe layer that could adversely influence the performance [36]. In addition to the substratespatterned by imprint lithography, a randomly textured substrate of Asahi U-type glass wasused to simultaneously fabricate a 160 nm thick a-Si:H cell under the same depositionconditions as the nanopatterned substrate.Since each successive layer is conformally deposited, the underlying back contactstructure for both the patterned and the randomly textured devices is transferred to the topinterface of the cell. Figure 2 shows tapping mode atomic-force microscopy (AFM) scans onthe indium tin oxide (ITO) top contact for both the imprint-patterned cell (a) and the randomlytextured Asahi sample (b). The imprinted substrate AFM scan reveals the underlying 175 nm diameter nanopatterns that are imprinted into the sol-gel glass layer, and transferred to theback contact of the cell at a pitch of 500 nm. In contrast, the randomly textured Asahi glassshows an uncorrelated distribution of height variations.3. ResultsFigure 3 shows current density/voltage (J-V) measurements taken under 100 mW cm 2 AM1.5 illumination for the 340 nm (a) and 160 nm (b) thick cells, all for cells with a plas monicscatterer diameter of 250 nm. In Fig. 3(a), data for 500 nm and 700 nm pitch are showntogether with the flat reference. In Fig. 3(b), data for the randomly textured Asahi glass cellsare also shown. For the 340 nm cells, the V oc is in the 840–850 mV range for all devicesmeasured, indicating that there is no significant difference in semiconductor and contactquality across the substrate. Data taken for several Ag particle diameters (200 nm, 225 nm,250 nm, 290 nm) all show similar J sc, V oc, and fill factor characteristics, with a slight increasein performance for larger diameter scatterers. However, a higher J sc is found for cells with a500 nm pitch than for cells with a 700 nm plas monic scatterer pitch. For the 500 nm pitchsamples, J sc improves by 27% compared to the flat cell. The highest efficiency recordedamong cells with the 340 nm thick a-Si:H layer (η= 6.6%) was found for a plasmonicscatterer pitch of 500 nm and a diameter of 250 nm.For the thinner cells [Fig. 3(b)], V oc is increased in comparison to the thicker cells, toaround 880-890 mV. We attribute this improvement to the decreased bulk recombination inthin layers demonstrating, as mentioned previously, an additional important advantage of theuse of thin active layers aside from the reduced costs [5]. At the same time, the fill factors#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A242Fig. 4. External quantu m efficiency spectra of nanopatterned and rand omly textu red cells frommeasurement and simulation. EQE spectra are shown in (a) for cells of thickness 160 nm,under one sun illumination at 0V bias. The primary enhancement in photocurrent over the flatreference cell occurs from 550 - 800 nm. The 500 nm pitch cell shows higher EQE than therand omly textu red Asahi cell. The inset of (a) shows EQE measurements of these two cells athigher spectral resolu tion. Electromag netic simulations of the generation rate spectra are shownin (b) for the same set of devices.have increased to 0.64. The 500 nm pitch, 250 nm diameter samples now show an increase inJ sc of 46% over the 160 nm thick flat cell. The best cell measured again had 250 nm diameter plasmonic scatterers and 500 nm pitch. This cell has an efficiency of 6.6%, which is similar tothe maximum efficiency found for the thick cell. While J sc is lower in the thin cells, theincreased V oc and fill factor cause the overall efficiency to remain the same between the two thicknesses. This demonstrates conclusively that plasmonic back reflectors can be used tomaintain efficiency while scaling to thinner solar cells. The J sc of the 500 nm patterned cell is improved by 50% compared to the flat reference cell.Remarkably, Fig. 3(b) also shows that J sc for the patterned cell with 500 nm pitch issignificantly larger than for the randomly textured cell with Asahi-U type of texture. Becausethe nanopatterned cells and the randomly textured Asahi sample both have comparable fillfactor and V oc, we can exclude a difference in semiconductor quality as an explanation for the improved J sc. We conclude that light trapping in the 500 nm pitch patterned cell is moreefficient than in the randomly textured sample.4. DiscussionTo further study the nature of the photocurrent enhancement, we measured external quantum efficiency (EQE) spectra, defined as the number of collected charge carriers per incidentphoton, using a Xenon lamp under light bias corresponding to approximately one sunillumination and 0 V bias. Figure 4(a) shows the EQE spectra for the same thin cells describedin Fig. 3(b). We note a slight increase in photocurrent on the blue side of the band for the 500nm pitch cell, from 350 nm – 550 nm, which we attribute to improved anti-reflectiveproperties of the corrugated top surface of the cell. The primary photocurrent enhancementoccurs in the 550 nm–800 nm spectral range. While the EQE of both the 500 nm and the 700nm pitch cells exceeds that of the flat reference cell, there is a pronounced difference betweenthe curves in the wavelength range from 550 nm to 700 nm. The cell on the randomly te xturedAsahi substrate has a very smooth EQE response, while the patterned devices exhibit peakedfeatures in the EQE curve, of which the peak wavelengths are reproducible for each pitch. Theinset of Fig. 4(a) shows EQE spectra of these two cells recorded with higher spectralresolution using a supercontinuum laser source filtered by a grating spectrometer. Thecomplex structure of the 500 nm pitch sample remains clearly visible compared to the smoothEQE spectrum of the randomly textured Asahi sample. Notably, the EQE of the 500 nm pitchcell exceeds that of the randomly textured Asahi sample in the 550–650 nm spectral range#128370 - $15.00 USD Received 12 May 2010; revised 7 Jun 2010; accepted 8 Jun 2010; published 24 Jun 2010 (C) 2010 OSA 21 June 2010 / Vol. 18, No. 102 / OPTICS EXPRESS A243Fig. 5. Angle-resolved photocurrent spectroscopy. Measured EQE versus incident waveleng thand incident angle for (a) the randomly textured Asahi cell and (b) the 500 nm pitchnanopatterned cell with 160 nm a-Si:H thickness. The Asahi cell shows a rather isotropicangular response, while the nanopatterned sample shows clear evidence of grating coupling toguided modes. The EQE enhancement for the nanopatterned sample, the ratio of (b) to (a), isshown in c; the calculated folded-zone dispersion diagram of the lowest-order TE and TMmodes is superimposed.where there is significant power in the solar spectrum. From 650 nm to 800 nm the features inthe spectra of the nanopatterned cell sharpen and alternately exceed and fall below the curvefor the randomly textured Asahi cell.We use full-field finite difference electromagnetic simulations to study the integratedcarrier collection rate from the nanostructured cell, with the cell layer thicknesses and optical constants taken from experimental values. Figure 4(b) shows the calculated carrier generationrate in the a-Si:H, modeled as G opt = ε”|E|2/2ħ, normalized by the incident photon flux acrossthe 350–800 nm. Our model assumes a geometry to describe the two patterned cells, wherethe nanostructures are taken to be hemispheres and the unit cell is chosen with either 500 or700 nm pitch and periodic boundaries. The surface structure for the randomly textured Asahicell was modeled using the AFM data shown in Fig. 2. The optical model accuratelyreproduces the spectral shape of the curves, including the enhanced absorption of the 500 nmpitch cell relative to the randomly textured cell and the reduced absorption for the 700 nmpitch cell. The enhancement and many of the peaked features are reproduced well in thesimulation, and deviations may be due to minor variations in layer thickness, pitch, optical constants, and differences between the real and assumed nanostructure geometry. The overallspectral correspondence between the electromagnetic simulation and the EQE measurementsstrongly suggests that the EQE enhancement is due to increased absorption from lighttrapping.To further investigate the nature of the light trapping mechanis m for the nanopatterned andrandomly textured Asahi glass samples we measured EQE spectra as a function of incidentangle for the thinner cells. Figure 5 shows intensity maps of these angle-resolved EQEspectra, for angle of incidence between 45° and + 45° from the substrate normal and for a。

journal of applied electrochemistry

Zinc±cobalt alloy electrodeposition from chloride baths R.FRATESI,G.ROVENTI,G.GIULIANI,Dipartimento di Scienze dei Materiali e della Terra,UniversitaÁdi Ancona,via Brecce Bianche,60131Ancona,ItalyC.R.TOMACHUKDepartamento de Engenharia de Materiais,Faculdade de Engenharia MecaÃnica,Universidade Estadual de Campinas,CEP13081-970,C.P.6122Campinas,SaÄo Paulo,BrazilReceived29July1996;revised21November1996Electrodeposition of Zn±Co alloys on iron substrate from chloride baths under galvanostatic and potentiostatic conditions were carried out.Current density,temperature and cobalt percentage in the bath were found to strongly in¯uence the composition of the deposits and their morphology. Changes in potentials,current e ciency and partial current densities were studied.The results show that the shift in potential and in the cobalt percentage of the deposits,for a particular current density during galvanostatic electrodeposition,does not always correspond to the transition from normal to anomalous codeposition.This shift is attributed to zinc ion discharge,which passes from underpo-tential to thermodynamic conditions.In the range of potentials for the underpotential deposition of zinc,the electrodeposition of zinc±cobalt alloys is discussed,emphasizing the in¯uence of the elec-trode potential on the composition and microstructure of the deposits.1.IntroductionThe electrodeposition of Zn alloys with group eight metals(Ni,Co and Fe)has recently been attracting interest because of the high corrosion resistance compared to that of pure zinc.The electrodeposition of these alloys is considered a codeposition of anomalous type,according to the Brenner de®nition [1];that is,the less noble metal deposits preferably on the cathode with respect to the more noble one.The operating conditions such as current density,tem-perature,pH,organic additives,bu er capacity, concentration of all solution components etc.lead to changes in the kinetics of electrodeposition,compo-sition and morphology of the coatings,as well as changes in their physico-mechanical characteristics [2±7].Therefore,normal codeposition is possible, even in particular electrodeposition conditions[8]. Several hypotheses have been advanced to explain the anomalous codeposition of alloys.The ideas are focused on phenomena occurring on the cathode surface.Dahms and Croll[9],who studied the anomalous electrodeposition of Fe±Ni alloy,con-cluded that the discharge of nickel is hindered by the formation of ferrous hydroxide on the electrode surface.Higashi et al.and Decroly[2,10,11]pro-posed the hydroxide suppression mechanism to ex-plain the anomalous codeposition of Zn±Co alloy in a sulfate bath.The discharge of the cobalt is inhibited by the formation of a zinc hydroxide®lm which o ers resistance to the transport of the Co2+ions.On the contrary Co(OH)2is not formed because the pH does not reach a critical value for precipitation.However,not all researchers agree on this mech-anism.Nicol and Philip[12]suggested that under-potential deposition(UPD)of the less noble metal on the cathode surface suppresses the deposition of the more noble metal.The term`underpotential deposi-tion'is used for the deposition of metal species on a foreign substrate in a potential region which is more positive than the equilibrium potential of the bulk deposit.Swathirajan[13]found that the strong inhi-bition of nickel deposition in the Zn±Ni alloy elec-trodeposition is due to submonolayer amounts of underpotential deposited zinc.Previously[3,8,14],anomalous codeposition of Zn±Ni and Zn±Co alloys has been treated,emphasiz-ing the importance of the kinetic parameters of the cathodic reactions:the iron group metals are gener-ally characterized by very low exchange current densities and re¯ect`electrochemical inertia'[15], unlike zinc,which shows high exchange current density.By studying the electrodeposition of Zn±Ni alloys from baths containing NH4Cl,no increase in the partial current of hydrogen reduction was ob-served at the potential values from which anomalous codeposition begins;this fact,plus the formation of zinc ammonium complexes,seems to exclude the precipitation of zinc hydroxide at the electrode sur-face.These results are supported by Mathias et al. [16,17].They found that,on using the Roehl bath (pH1.6),the electrodeposition of Zn±Ni alloys is anomalous even though the hydrogen current is not high enough to raise the interfacial pH much above the bulk pH,as would be necessary for the formation of Zn(OH)2.These authors calculated that the zincJOURNAL OF APPLIED ELECTROCHEMISTRY27(1997)1088±10940021-891XÓ1997Chapman&Hall1088exchange current density is®ve orders of magnitude higher than that of nickel and attributed the anom-alous codeposition to the intrinsically slow nickel kinetics.In the present work,the codeposition of Zn±Co alloys from a chloride bath has been studied.The bath was free of additives such as levellers or bright-eners since they can strongly in¯uence the composi-tion and the morphology of the alloys deposited on the cathode.2.Experimental detailsZn±Co alloys were obtained at various temperatures (25,40and55°C),under galvanostatic and potent-iostatic conditions using baths of the following com-position:ZnCl231.1±70.0g dm A3;CoCl2á6H2O90.7±15.2g dm A3(M tot37.4g dm A3);H3BO326g dm A3; KCl220g dm A3(pH4.3,4.2and3.9for baths with Co10,30and60%,respectively).Boric acid is used extensively in Zn±Co and Zn±Ni alloy electro-depositions,as a bu er to prevent the pH rise at the electrode surface;however,the function of H3BO3is a controversial subject[18,19].Tests with only cobalt or zinc,maintaining the total metal quantity and the other components of the bath constant,were also carried out.Solutions were prepared with doubly distilled water and analytical grade reagents. Electrodeposits were obtained on both sides of mild steel discs,1mm thick(exposed area15cm2). Before electrodeposition,the samples were smoothed with emery paper and any grease was removed from their surface by anodic and cathodic electrolysis for 2min in an aqueous NaOH60g dm A3solution at4V against graphite anodes.The samples were then neutralized in a2%HCl solution and rinsed with distilled water.A PVC cell1dm3in capacity was used.The steel cathode was centrally positioned,whereas two zinc anodes(total area150cm2)were symmetrically po-sitioned with respect to the central cathode.Before immersion in the bath,the zinc anodes were im-mersed for3h without current¯ow,in a solution of similar composition at40°C.The zinc sheets were coated with a dark cobalt layer,so avoiding the de-pletion of cobalt in the bath due to its cementation on the zinc anodes.Cathode potential measurements were performed during electrodeposition using a Ag/ AgCl reference electrode.Polarization was applied when the cathode was immersed in the bath and electrolysis was continued until deposits at least6l m thick were obtained.During the electrodeposition, the cathodic solution was mechanically stirred.The amount of electrical charge during potentiostatic tests was registered by means of a coulometer AMEL model731.At the end of each deposition,the disc cathodes were thoroughly washed with water and then ethanol,hot air dried and weighed.To determine the percentage composition of the electrodeposited alloys,the deposits were stripped in a minimum volume of1:3HCl solution and analysed for cobalt and zinc by means of inductively coupled plasma spectroscopy(ICPS).By means of Faraday's law,the partial currents of zinc and cobalt were cal-culated and their respective polarization curves were plotted.The morphology of the deposits was observed by means of scanning electron microscopy(SEM).The deposited phases were analysed by X-ray di raction with Cu K a(k 15.4nm)and identi®ed by powder di raction®le card(JCPDS).All the tests were repeated three times with good agreement of the results.3.Results and discussionThe data shown in Fig.1were obtained by gal-vanostatic electrodeposition at25°C.They show the in¯uence of current density on the chemical compo-sition of the deposits obtained from baths containing di erent percentages of cobalt ions.The percentage of Co present in the baths and deposits,indicated by Co b and Co d was calculated as follows:Co a%Co a gCo Zn a gÂ100The trend of the curves is similar to that already known for codepositions of anomalous type[2,8]:the percentage of cobalt deposited on the cathode de-pends on the cobalt/zinc concentration ratio in the bath and is quite constant for a large range of current density,where the deposition of zinc and cobalt is of anomalous type.At low current densities the per-centage of cobalt in the deposits increases abruptly reaching values of almost100%and the codeposition becomes normal.The value of current density corre-sponding to the transition from normal to anomalous codeposition is called the transition current density (i T)and it depends,at constant temperature,on the bath chemical composition.In Fig.1the letters(a), (b)and(c)show the points of the respective curves where the percentage of cobalt in the deposits isequalZINC±COBALT ALLOY ELECTRODEPOSITION1089to that in the bath;the`imaginary'line interpolating the three points represents the composition reference line(CRL).With increase in cobalt/zinc concentration ratio,a higher current density is necessary for anom-alous deposition to occur.The temperature strongly a ects the composition of the deposits,as shown in Fig.2.On increasing the temperature,the sharp decrease in cobalt percentage in the coatings occurs at higher current densities and this is associated with the abrupt shift of cathodic potential toward more negative values.At tempera-tures of25and40°C the transition from normal to anomalous codeposition(points A and B in Fig.2) corresponds to the rapid shift in the cobalt percentage of the deposits and in the cathodic potentials.In the Zn±Co electrodeposition carried out at55°C,at about3.6mA cm A2the cobalt percentage of the de-posits decreases abruptly,but it still remains higher than the cobalt percentage in the bath.In spite of thesharp shift in cathodic potential,normal/anomalous transition does not take place.This behaviour is more evident in the electrodeposition carried out at55°C, but in a solution with a cobalt ion concentration of 60%(Fig.3).In this case the characteristic shift in the cathodic potential,as well as the reduction in cobalt percentage of the deposits at about35mA cm A2,are still less marked and the codeposition always remains normal even at relatively high current densities (50mA cm A2).The alloy current e ciency is almost 100%and therefore the current e ciency of hydrogen is very low throughout the whole current density range studied.Figures2and3show that only for some experimental conditions does the shift in po-tential and in the cobalt percentage of deposits cor-respond to the transition from normal to anomalous electrodeposition.Only in these latter cases,the cur-rent density corresponding to the sharp shift in cathodic potential is the transition current. Figure4shows the polarization curves obtained by galvanostatic tests at55°C using baths containing di erent cobalt/zinc concentration ratios.The curves obtained from the baths containing only zinc or co-balt ions are also indicated.The cobalt deposition from the solution containing only cobalt ions starts at about A550mV,while the zinc deposition from baths containing only zinc ions starts at about A1000mV. The alloy polarization curves are close to the curve for Co at low current densities,while they are very close to the curve for Zn after the rapid shift in po-tential.The sharp variations in cathodic potential are due to the zinc ions discharge which passes from underpotential to thermodynamic conditions.The galvanostatic tests do not shed light on the phe-nomena that occur on the electrode in the range in which the potential rapidly changes. Therefore,potentiostatic electrodeposition was carried out in the current range where the cathodic potential is unstable(Fig.5).The curves related to pure zinc or pure cobalt are similar to those obtained by galvanostatic tests.The zinc and the cobalt ions separately begin deposition only at their respective equilibrium potential of the bulk deposit.Thecurves 1090R.FRATESI ET AL.due to the deposition of Zn±Co alloys,compared to those of galvanostatic type,are more detailed.At more positive potential values the curves are similar to those of pure cobalt deposition,but around ±800to ±850mV the current signi®cantly drops and then,at potential values more negative than ±950mV it again sharply increases.The total electrolysis current together with the partial currents related to cobalt,zinc and hydrogen and also the zinc percentage in the alloy deposit ob-tained in the potential range ±660to ±1100mV are shown in Fig.6.In the operating conditions related to Fig.6,the trend of the current density due to the alloy is quite similar to the partial current density of cobalt up to about ±800mV,and the deposits contain more than 90%of cobalt in the range ±600to ±800mV.The zinc deposition starts around ±700mV and its per-centage in the deposits increases as the cathodic po-tential change toward more negative values.The zincreduction in this ®eld of potential is assisted by the presence of cobalt ions in the solution,indeed the partial current density of zinc depends on the per-centage of cobalt in the bath,when the other exper-imental conditions are kept constant (Fig.7);a connection between i Co and i Zn was found previously,though for di erent experimental conditions [20].How the cobalt supports the underpotential elec-trodeposition of zinc is not clear at the moment.At a potential of ±800mV vs Ag/AgCl,the percentage of zinc in the deposits is about 14%and the partial current density of cobalt reaches a maximum value;at ±830mV the percentage of zinc in the deposits reaches 19%and the partial current densities of co-balt and of zinc begin to decrease.The zinc percent-age in the deposits remains quite constant until about ±900mV (Zn d ~23%),then it rapidly begins to in-crease again together with the partial current of zinc (i Zn ).The cathodic reduction of zinc prevails over cobalt reduction only at potential values more nega-tive than about ±970mV,where it begins to discharge in thermodynamic conditions.In these conditions,however,the codeposition is not always of anoma-lous type.Using the same bath,but carrying out the tests at 25°C (Fig.8),the trend of the curves appears the same as in Fig.6.At this temperature value the in-hibition of the cobalt ions discharge starts when the zinc percentage in the deposits is about 15%.In this case however,on the contrary to what happens in the operating condition related to Fig.6,the transition from underpotential to thermodynamic electro-deposition corresponds to the transition from normal to anomalous codeposition.In the range of potentials where the zinc reduces in underpotential conditions,the deposition of Zn±Co alloys is always of normal type.It must be emphasized that,in the range ±700~±800mV,in spite of the high percentage of zinc (higher than 10%),the inhibition of cobalt ions dis-charge does notoccur.ZINC±COBALT ALLOY ELECTRODEPOSITION 1091The increase in pH at the cathodic interface is generally considered responsible for the inhibition of cobalt discharge in the hydroxide suppression mech-anism,as mentioned in the introduction [2,5].The present work does not seem to con®rm this theory since the partial current density of hydrogen remains quite constant and very low (Figs 6and 8).Therefore,the inhibition of cobalt ion reduction in these oper-ating conditions does not seem connected with an increase in pH.The observation carried out by SEM on the sur-faces of the deposits obtained at the potential values of Fig.6,are shown in Figs 9±13.Deposits obtained at ±700mV (Fig.9,Zn d 0.5%)are formed of pure cobalt and are not cracked,according to the solu-bility of Zn in Co,which is less than 3%[18].The coatings obtained at ±750mV are cracked (Fig.10,Zn d 8%);in the range ±800to ±830mV the deposits are cracked and do not adhere to the steel substrate (Fig.11,Zn d 14%).At more negative potential val-ues,in the range where the zinc percentage remains quite constant and the partial current density of co-balt decreases,the deposits are still cracked,but they adhere again to the steel substrate (Fig.12,Zn d 23%).The cracking of the cobalt deposits with inclusion of zinc above 3%was found by other authors [10,11];the higher percentage of zinc in the alloy produces more internal stresses in the deposits,until a change in the crystalline structure occurs which reduces these internal stresses.The maximum in the internal stresses coincides with the maximum in the current density of cobalt (i Co ).These deposits show a brittle behaviour with the surface fracture that looks like a vitreous fracture (Fig.13).At potentials where the zinc can reduce in thermodynamic conditions and the partial current density of zinc becomes higher than the partial current density of cobalt,the deposition of compact and well formed zinc-rich deposits occurs (Fig.14,Zn d 60%).The in¯uence of the electrode potential on the deposition of various phases of di erent zinc com-position from the same electrolyte was also foundbyFig.9.Microstructure of zinc±cobalt alloy obtained by potentio-static electrodeposition at ±700mV vs Ag/AgCl.Co b 30%;T 55°C;Zn d0.5%.Fig.10.Microstructure of zinc±cobalt alloy obtained by potent-iostatic electrodeposition at ±750mV vs Ag/AgCl.Co b 30%;T =55°C;Zn d8%.Fig.11.Microstructure of zinc±cobalt alloy obtained by potent-iostatic electrodeposition at ±800mV vs Ag/AgCl.Co b 30%;T 55°C;Zn d 14%.1092R.FRATESI ET AL.other authors for Zn±Ni and Zn±Co alloys elec-trodeposition [13,21].The X-ray analysis do not always permit to iden-tify the phases present in the coatings (Fig.15).De-posits of only cobalt are not crystalline,the peaks have very low intensity and can be attributed to low content of crystalline a Co in the quite completely amorphous deposit (Fig.15,line a).The presence of zinc in the range 0.5~23%makes the deposits more and more amorphous (Fig.15lines b,c,d,e).When the zinc reaches 60%,the deposits become crystalline and the zinc peaks clearly appear (Fig.15,line f ).4.ConclusionsThe deposition of Zn±Co alloys is generally a code-position of anomalous type,but,in particular elec-trodeposition conditions,it is possible to obtain normal codeposition.The shift in potential and in cobalt percentage in the deposits,which occur at a particular current density during galvanostatic electrodeposition,doesnot always correspond to the transition from normal to anomalous codeposition.The sharp variations in cathodic potential are due to the zinc ions discharge which passes from underpotential to thermodynamic conditions.In the underpotential deposition,the electrode potential determines the deposition of various phases of di erent composition.The inclusion of zinc above 3%causes cracking of the cobalt deposits and the further increase in the percentage of zinc in the alloy produces more internal stresses in the deposits.TheFig.12.Microstructure of zinc±cobalt alloy obtained by potent-iostatic electrodeposition at ±870mV vs Ag/AgCl.Co b 30%;T 55°C;Zn d23%.Fig.13.Fracture of Zn±Co alloy (Zn d 23%)obtained by bending of the coatinglayer.Fig.14.Microstructure of zinc±cobalt alloy obtained by potent-iostatic electrodeposition at ±1000mV vs Ag/AgCl.Co b 30%;T 55°C;Zn d23%.ZINC±COBALT ALLOY ELECTRODEPOSITION 1093inhibition of the cobalt ions discharge starts only when the zinc percentage in the deposits reaches about15%.The maximum in the internal stresses coincides with the maximum in the current density of cobalt(i Co).At potentials where the zinc can reduce in ther-modynamic conditions,deposits containing more than60%zinc become compact and well formed, even when the codeposition is still of normal type.AcknowledgementsThe research was supported by Conselho Nacional de Desenvolvimento CientõÂ®co e TecnoloÂgico(CNPq), Brasil.References[1] A.Brenner,`Electrodeposition of alloys',vols I and II,Academic Press,New York and London(1963). [2]K.Higashi,H.Fukushima,T.Urokawa,T.Adaniya andK.Matsudo,J.Electrochem.Soc.128(1981)2081. [3]L.Felloni,R.Fratesi,E.Quadrini and G.Roventi,J.Appl.Electrochem.17(1987)574.[4]L.Felloni,R.Fratesi and G.Roventi,Proceedings of theXXII International Metals Congress,Bologna,Italy(17±19May1988),p.687.[5]H.Fukushima,T.Akiyama,K.Higashi,R.Kammel andM.Karimkhani,Metall.42(1988)242.[6]R.Albalat,E.GoÂmez,C.Muller,M.Sarret,E.ValleÂs andJ.Pregonas,J.Appl.Electrochem.20(1989)529. [7]R.Albalat,E.GoÂmez,C.Muller,M.Sarret,E.ValleÂs andJ.Pregonas,ibid.20(1990)635.[8]R.Fratesi and G.Roventi,J.Appl.Electrochem.22(1992)657.[9]H.Dahms and I.M.Croll,J.Electrochem.Soc.112(1965)771.[10]J.Mindowicz,C.Capel-Boute and C.Decroly,Electro-chim.Acta10(1965)901.[11]M.Yunus,C.Capel-Boute and C.Decroly,ibid.10(1965)885.[12]M.I.Nicol and H.I.Philip,J.Electroanal.Chem.70(1976)233.[13]S.Swathirajan,ibid.221(1987)211.[14]R.Fratesi and G.Roventi,Mater.Chem.Phys.23(1989)529.[15]R.Piontelli,in`Atlas of Electrochemical Equilibria inAqueous Solutions'(edited by M.Pourbaix),NACE,Huston,Texas(1974),p.11.[16]M.F.Mathias and T.W.Chapman,J.Electrochem.Soc.134(1987)1408.[17]Idem,ibid.137(1990)102.[18] C.Karwas and T.Hepel,J.Electrochem.Soc.136(1989)1672.[19]M.Pushpavanam and K.Balakrishnan,J.Appl.Electro-chem.26(1996)283.[20]M.Maja,N.Penazzi,R.Fratesi and G.Roventi,J.Electrochem.Soc.129(1982)2695.[21]M.L.AlcalaÂ,E.GoÂmez and E.ValleÂs,J.Electroanal.Chem.370(1994)73.1094R.FRATESI ET AL.。

极化曲线英文缩写

极化曲线英文缩写The abbreviation of Polarization Curve is PC. The polarization curve is a plot of the voltage (or potential) versus the current density for an electrochemical cell. It is a fundamental tool for understanding the behavior of electrochemical systems, and it provides important information about the kinetics and mechanisms of electrochemical reactions.The polarization curve is typically obtained by measuring the current density as a function of the applied voltage, while the cell is operating under steady-state conditions. The resulting curve can be divided into three regions: the activation region, the ohmic region, and the concentration region.In the activation region, the current density increases rapidly with increasing voltage, due to the activation overpotential associated with the electrochemical reaction. This region provides information about the rate at which the electrochemical reaction takes place, and it is often used to determine the exchange current density and the Tafel slope.The ohmic region of the polarization curve is characterized by a linear relationship between the current density and the voltage, and it is related to the resistance of the electrolyte and the electrodes. By analyzing this region, it is possible to determine the ohmic resistance of the electrochemical cell, as well as the conductivity of the electrolyte.The concentration region of the polarization curve occurs at high current densities, where mass transport limitations begin to affect the electrochemical reaction. In this region, the current density becomes independent of the voltage, and it is governed by the diffusion of reactants to the electrode surface. The concentration region provides valuable information about the mass transport properties of the electrochemical system, and it can be used to determine the diffusion coefficient of the reactants.Overall, the polarization curve is a powerful tool for characterizing the behavior of electrochemical systems. By analyzing the different regions of the curve, it is possible to gain insights into the kinetics, mechanisms, and transport properties of electrochemicalreactions. This information is crucial for the design and optimization of electrochemical devices and processes, such as fuel cells, batteries, and corrosion protection systems.In conclusion, the polarization curve is an essential tool for understanding the behavior of electrochemical systems. Its ability to provide detailed information about the kinetics, mechanisms, and transport properties of electrochemical reactions makes it invaluable for researchers and engineers working in the field of electrochemistry. By carefully analyzing the polarization curve, it is possible to gain a deeper understanding of electrochemical processes and to develop more efficient and reliable electrochemical technologies.。

提高钐钡铜氧钉轧能力的研究

Home Search Collections Journals About Contact us My IOPscienceThe influence of the geometric characteristics of nanorods on the flux pinning in high-performance BaMO3-doped SmBa2Cu3O y films (M = Hf, Sn)This content has been downloaded from IOPscience. Please scroll down to see the full text.2014 Supercond. Sci. Technol. 27 065001(/0953-2048/27/6/065001)View the table of contents for this issue, or go to the journal homepage for moreDownload details:IP Address: 58.198.86.19This content was downloaded on 10/09/2014 at 04:41Please note that terms and conditions apply.Superconductor Science and T echnology Supercond.Sci.Technol.27(2014)065001(7pp)doi:10.1088/0953-2048/27/6/065001The inﬂuence of the geometric characteristics of nanorods on theﬂux pinning in high-performance BaMO3-doped SmBa2Cu3O yﬁlms(M=Hf,Sn)A Tsuruta1,Y Yoshida1,Y Ichino1,A Ichinose2,K Matsumoto3andS Awaji41Department of Energy Engineering and Science,Nagoya University,Furo-cho,Chikikusa-ku,Nagoya464-8603,Japan2Electric Power Engineering Research Laboratory,Central Research Institute of the Electric PowerIndustry,2-6-1Nagasaka,Yokosuka,Kanagawa240-0196,Japan3Department of Materials Science and Engineering,Kyushu Institute of Technology,1-1Sensui-cho,Tobata-ku,Kitakyushu804-8550,Japan4Institute for Materials Research,Tohoku University,Katahira2-1-1,Aoba-ku,Sendai980-8577,JapanE-mail:tsuruta-akihiro11@ees.nagoya-u.ac.jpReceived12December2013,revised28January2014Accepted for publication31January2014Published3April2014AbstractRecently,the BaHfO3(BHO)nanorod has attracted attention as a new c-axis-correlatedpinning center in REBa2Cu3O yﬁlms.We fabricated SmBa2Cu3O y(SmBCO)ﬁlms with BHOnanorods using an alternating-targets technique with pulsed laser deposition on single-crystalLaAlO3(100)substrates,and then compared the microstructure andﬂux pinning propertieswith those of BaSnO3(BSO)-doped SmBCOﬁlms.Transmission electron microscopyobservations indicated that the BHO and BSO nanorods both grew straight,but the inclinationof the BHO nanorods from the c-axis of the SmBCO was less than that of the BSO nanorods.The inclination had a strong inﬂuence on theﬂux pinning property.Theﬂux pinning force ofthe BHO-doped SmBCOﬁlm(F MAXp=28.0GN m−3with J c=2.0MA cm−2at77K under1.4T)became stronger than that of the BSO-doped SmBCOﬁlm(F MAXp=24.5GN m−3withJ c=1.4MA cm−2at77K under1.8T)due to the shape of the BHO nanorods withoutinclining.Keywords:BaHfO3,ﬂux pinning,SmBa2Cu3O y,thinﬁlm1.IntroductionIn order to use REBa2Cu3O y(REBCO:RE=Y,Gd,Er, Nd,Sm)superconducting coated conductors(CC)in various applications,particularly in superconducting magnets,it is essential to improve the critical current density(J c)andﬂux pinning force(F p)at various temperatures and under variousmagneticﬁelds[1].It is well known that the introduction of artiﬁcial pinning centers(APCs)into REBCOﬁlms can improve their superconducting properties in magneticﬁelds.So far,there have been reports on the introduction of APCs into REBCOﬁlms—such as Y2O3nanoparticles,centers produced by heavy-ion irradiation,and BaZrO3(BZO)nanoparticles[2–7].BaMO3(BMO:M=Zr,Sn)and BaNb2O6or RE3TaO7 (RTO)self-organize into nanorods within the REBCO matrix, and these nanorods become columnar defects[6,8–12].The nanorods grow along the c-axis of the REBCOﬁlms,and are effectiveﬂux pinning centers under magneticﬁelds applied parallel to the c-axis of the REBCOﬁlms.Interestingly,these nanorods have only been grown by vapor phase epitaxialmethods such as pulsed laser deposition(PLD)and chemi-cal vapor deposition(CVD).Theﬂux pinning force of theBMO nanorods was higher than that of other APCs.Meleet al reported that4wt%BaSnO3(BSO)-doped YBa2Cu3O y(YBCO)ﬁlms deposited by PLD on a single-crystal SrTiO3substrate had a very high F p(28.3GN m−3)at77K[13].Thisvalue is the highest yet reported at77K.Recently,in order to control theﬂux pinning propertiesand improve the anisotropic J c of REBCOﬁlms under amagneticﬁeld,BMO nanorods were combined with otherAPCs and nanoengineering techniques[14–19].Generally,BMO nanorods play an important role in increasing the in-ﬁeldJ c,controlling theﬂux pinning properties and the utilizationof REBCO CCs.BaHfO3(BHO)has recently received con-siderable attention as a new BMO material.It was reportedthat a BHO-doped GdBa2Cu3O y(GdBCO)ﬁlm deposited byPLD on an IBAD-MgO substrate had an isotropic pinningforce,and this pinning force was effective at low temperaturesunder strong magneticﬁelds[20].Additionally,these super-conducting properties were superior to those of other BMOssuch as BSO and BZO.Microstructural observations indicatedthat the BHO also grew into nanorods,and that these nanorodswere smaller in diameter and shorter than other nanorods.Wealso described BHO-doped SmBa2Cu3O y(SmBCO)ﬁlms,andshowed that the BHO nanorods had a strongﬂux pinning forceat low temperatures[21].However,it is not yet clear why theﬂux pinning forceof the BHO nanorods was stronger than that of other BMOnanorods.For the investigation of new superior APC mate-rials and the development of future CCs,it is important tounderstand the differences between BHO nanorods and otherBMO nanorods.In this study,we investigated the differencesinﬂux pinning properties between BHO nanorods and otherBMO nanorods.We fabricated a BHO-doped SmBa2Cu3O y(SmBCO)ﬁlm and a BSO-doped SmBCOﬁlm.Then,wecompared the superconducting properties and microstructuresof theseﬁlms.To simplify this comparison,we used BHO and BSOnanorods with similar diameters in order to exclude theinﬂuence of size from the comparison of theﬂux pinningforces.2.Experimental detailsBMO-doped SmBCOﬁlms and non-doped SmBCO(pureSmBCO)ﬁlms were deposited on single-crystal LaAlO3(100)(LAO)substrates using a conventional PLD method with a KrF(λ=248nm)excimer laser at a repetition rate of10Hz.Thelaser energy density,the distance between the substrate andtargets,and the O2partial pressure during the deposition were1.7J cm−2,70mm,and400mTorr,respectively.In order toadjust the diameters of the BHO and BSO nanorods to the samevalue,we controlled the substrate temperature(T s)during the deposition and the BMO content of eachﬁlm.The T s valueof the BHO-doped SmBCOﬁlm and of the pure SmBCOﬁlmwas940◦C,and that of the BSO-doped SmBCOﬁlm was810◦C.We conﬁrmed that the superconducting properties ofpure SmBCOﬁlms deposited at940and810◦C were almost the same.For example,the T c and self-ﬁeld J c at77K(J selfc) of a pure SmBCOﬁlm deposited at940◦C were92.5K and 3.3MA cm−2,compared to92.8K and3.9MA cm−2for aﬁlm deposited at880◦C.The BHO content and BSO content were 8.6mol%(3.7vol.%)and12.6mol%(4.8vol.%),respectively. The BHO-doped SmBCOﬁlms and the BSO-doped SmBCO ﬁlms were deposited by an alternating-targets technique in a pulsed laser deposition(ALT–PLD)method.The ALT–PLD method can more easily fabricate certainﬁlms containing different amounts of additive materials than the usual PLD method using a pre-mixed target.Furthermore,the ALT–PLD method can prevent chemical reactions between the parent phase and the additive materials when preparing the target.In this study,we used a pure SmBCO target and a pure BHO or BSO target to deposit BMO-doped SmBCOﬁlms via the ALT–PLD method.Weﬁxed the number of the laser pulses to a pure SmBCO target and a pure BHO target as80and16 pulses in an exchanging cycle for the BHO-doped SmBCO ﬁlm.In the case of the BSO-doped SmBCOﬁlm,the number of the laser pulses on a pure SmBCO target and a pure BSO target were80and4pulses in an exchanging cycle.The thickness of a layer for an exchanging cycle was below1nm. The crystalline orientation of theﬁlms was evaluated by x-ray diffraction(XRD)analysis and the microstructure of theﬁlms was investigated using high-resolution transmission electron microscopy(TEM).The diameter and number density of the nanorods were measured from cross-sectional and plan-view TEM images,respectively.The BHO and BSO content of eachﬁlm were measured by scanning electron microscopy with energy dispersive x-ray spectroscopy(SEM–EDX).The resistivity and critical current under various magneticﬁelds were measured with a physical property measurement system (PPMS)using a standard four-probe method.T c was deﬁned from the temperature dependence of the resistivity using a resistivity criterion of0.1µ cm,and the probe current was ﬁxed at about25A cm−2.J c was evaluated from current versus voltage curves with an electricﬁeld criterion of1µV cm−1. The magneticﬁeld in the J c–B curve measurements ranged from0to9T,and the angular range in the J c–θcurve measurements was−20◦to130◦,with B ab deﬁned as90◦. In all of the J c measurements,the current and magneticﬁeld were always at right angles.The thicknesses of theﬁlms were measured by TEM observation and inductively coupled plasma atomic emission spectrometry.The thicknesses of theﬁlms ranged from280to740nm.3.Results and discussionThe XRD results(not reported here)indicated that the BMO-doped SmBCOﬁlms and the pure SmBCOﬁlm grew on the LAO substrates with an epitaxial relationship of (001)[100]SmBCO (001)[100]LAO.The a-axis-oriented phase was only observed in the BSO-doped SmBCOﬁlm, because the T s of the BSO-doped SmBCOﬁlm was lower than the T s of the BHO-doped SmBCOﬁlm,in order to match the nanorod diameters.The mixing ratio of a-axis-oriented grains to c-axis-oriented grains was3.0%,as calculated from the XRD intensity ratio of SmBCO200and005reﬂections.Figure1.Cross-sectional TEM images of(a)the BHO-doped SmBCOﬁlm and(b)the BSO-doped SmBCOﬁlm fabricated on LAO(100) substrates using the ALT–PLDmethod.Figure2.High-magniﬁcation cross-sectional TEM images of(a)the BHO-doped SmBCOﬁlm and(b)the BSO-doped SmBCOﬁlm under the same magniﬁcation.We conﬁrmed that all of theﬁlms showed good crystallinity,based on rocking curves of the SmBCO005reﬂection and theφ-scan measurements of the SmBCO102reﬂection.In order to observe the shape of the BHO nanorodsand compare them to the BSO nanorods,we observed themicrostructures of the BHO-doped SmBCOﬁlm and theBSO-doped SmBCOﬁlm using TEM.Figures1(a)and(b)show cross-sectional TEM images of the BHO-doped SmBCOﬁlm and the BSO-doped SmBCOﬁlm,respectively.In bothﬁlms,the BHO or BSO formed many nanorods,and all of thesenanorods grew straight from the surface of the substrate to thesurface of theﬁlm.There was no coalescence or ramiﬁcationof the nanorods in eitherﬁlm.In addition,ﬁgures2(a)and(b)show high-magniﬁcation cross-sectional TEM images of theﬁlms at the same magniﬁcation.We observed moire fringes inbothﬁlms,indicating that the BHO and BSO nanorods grewepitaxially in the SmBCO matrix.Table1shows parameters characterizing the shape of thenanorod such as the average diameter(d),number density(n),matchingﬁeld(Bφ),and halfwidth of the inclinationangle distribution( α).The matchingﬁeld Bφwas calculatedfrom Bφ=nφ0,whereφ0is theﬂux quantum.The inclinationangles of the BHO and BSO nanorods were measured fromthe cross-sectional TEM images.Figure3shows a schematicdiagram deﬁning the inclination angles of the nanorods.Inthis study,the BHO and BSO nanorods grew straight fromthe substrate to theﬁlm surface,so the nanorods can beapproximated as straight lines.The inclination angle of thenanorods was calculated fromα=arctan(g/t),where g istheFigure3.Schematic diagram showing the deﬁnition of the nanorodinclination angle.Table1.Average diameter(d),number density(n),matchingﬁeld(Bφ),and halfwidth of the inclination angle distribution( α)forBHO and BSO nanorods.Nanorod d(nm)n(µm−2)Bφ(T) α(deg)BaHfO313.5708 1.47 3.35BaSnO314.3900 1.868.13shifted distance of the nanorods in the direction parallel to thesubstrate surface and t is the thickness of theﬁlm.The diameters of the BHO and BSO nanorods listed intable1are almost the same,and these diameters are sufﬁcientlylarger than twice the coherence length(about8nm)in theFigure4.Distribution of the inclination angle for(a)BHO nanorods and(b)BSO nanorods.ab-plane at77K.Because theﬂux pinning energy per unit length(u0)of a columnar defect depends strongly on the diameter of the defect[22],the u0values of the BHO and BSO nanorods were also almost the same.Ozaki et al reported that the diameter of BZO nanorods in LTG-SmBCO+BZO ﬁlms became larger with increasing substrate temperature[17]. According to this report,if we fabricated a BHO-doped SmBCOﬁlm with the same T s as a BSO-doped SmBCOﬁlm, the diameter of the BHO nanorods should be much smaller than that of the BSO nanorods.The number density of the BHO nanorods was lower than that of the BSO nanorods.This was because the BHO content in the BHO-doped SmBCOﬁlm was lower than the BSO content in the BSO-doped SmBCOﬁlm.Besides this low number density of BHO nanorods,the matchingﬁeld was also lower.The most noteworthy parameter in table1is the halfwidth of the inclination angle distribution, α. αfor the BHO nanorods was smaller than that of the BSO nanorods,indi-cating that the BHO nanorods were straighter than the BSO nanorods,and had a lower inclination.The reason for this could simply be that the T s of the BHO-doped SmBCOﬁlm was higher than that of the BSO-doped SmBCOﬁlm,which corresponds to the tendencies observed in previous reports [17,23,24].Considering only this result,theﬂux pining force of the BHO-doped SmBCOﬁlm might be stronger than that of the BSO-doped SmBCOﬁlm,especially in B c.In order to investigateαin more detail,we prepared histograms of the αvalues.Then,weﬁxed the centers of theαdistributions at 0◦.Although the values were slightly shifted along the c-axis direction of the SmBCO,the gaps were very small.Figures4(a) and(b)show the distributions ofαfor BHO and BSO nanorods, respectively.The BHO nanorods were distributed with a width of8◦.On the other hand,the BSO nanorods had a broad distribution with a width of16◦.These results suggest that the ﬂux pinning force for aﬁeld applied parallel to the c-axis of SmBCO with BHO nanorods is stronger than that with the BSO nanorods because the inclination angle distribution of the BHO nanorods is narrower.Microstructural observations indicated that the nanorods grew straight and with comparable diameters in the twoﬁlms.However,there was a remarkable difference between the inclination angle distributions of the twoﬁlms.Table2.Critical temperatures(T c),critical current densities in the self-ﬁeld(J selfc),and c-axis lengths for SmBCOﬁlms.FilmT c(K)J selfc(MA cm−2)c-axis length(Å)Pure SmBCO92.5 3.311.73BHO-doped SmBCO92.3 6.211.75BSO-doped SmBCO90.0 3.611.77We compared the superconducting properties andﬂux pin-ning properties of the BHO-doped and BSO-doped SmBCOﬁlms.Table2shows the T c and J selfcvalues and the c-axis lengths for eachﬁlm.T c for the BSO-doped SmBCOﬁlm was signiﬁcantly reduced to90.0K,compared with92.5K for the pure SmBCOﬁlm.The c-axis length of the BSO-doped SmBCOﬁlm was longer than that of the pure SmBCOﬁlm. This result is consistent with many reports that the doping of BMO into REBCOﬁlms lowers T c by expanding the c-axis length of the REBCO because of the stress arising from the lattice misﬁt between REBCO and BMO[13,25]. In BHO-doped SmBCOﬁlm,on the other hand,the c-axis expansion from its length in the pure SmBCOﬁlm was less than that in the BSO-doped SmBCOﬁlm.The T c of the BHO-doped SmBCOﬁlm was almost the same as the T c of the pure SmBCOﬁlm.These observations indicated that the lattice stress in the BHO-doped SmBCOﬁlm was lower than that in the BSO-doped SmBCOﬁlm.However,the lattice misﬁt between BHO and SmBCO is6.5%,which is larger than the 5.4%misﬁt between BSO and SmBCO[26,27].Therefore, signiﬁcant T c reduction and c-axis expansion should occur in the BHO-doped SmBCOﬁlm.However,the opposite tendency was observed in our experimental results concerning T c andthe c-axis length,as shown in table2.Furthermore,J selfcfor the BHO-doped SmBCOﬁlm was nearly twice that for the pure SmBCOﬁlm and the BSO-doped SmBCOﬁlm.These results imply that the introduction of BHO into the SmBCO ﬁlms had no inﬂuence on T c and had a positive inﬂuence onJ selfc,unlike the usual BMO material case.Figure5shows the magneticﬁeld dependence of J c for SmBCOﬁlms with a magneticﬁeld applied parallel to the c-axis of the SmBCO(B c)at77K.In these BMO-doped SmBCOﬁlms,the J c values were higher than those for the pureFigure5.Magneticﬁeld dependence of J c for a pure SmBCOﬁlm, a BHO-doped SmBCOﬁlm,and a BSO-doped SmBCOﬁlm at77K in B c.The arrows indicate the edges of the J cplateaus.Figure6.Magneticﬁeld dependence of F p for a pure SmBCOﬁlm, a BHO-doped SmBCOﬁlm,and a BSO-doped SmBCOﬁlm at77K in B c.SmBCOﬁlm under all applied magneticﬁelds.We observed plateaus,where J c gradually decreased with increasingﬁeld strength around1T in bothﬁlms.The ending points of these plateaus are indicated by arrows in theﬁgure.It was known that these points correspond with the matchingﬁeld of theﬁlms.Under weakerﬁelds where plateaus are observed, single-vortex pinning by the BMO nanorods was dominant. Under strongerﬁelds,corrective pinning of theﬂux bundles by the BMO nanorods was dominant.The J c values of the BHO-doped SmBCOﬁlm were higher than those of the BSO-doped SmBCOﬁlm in both weaker and strongerﬁelds. This suggests that the single-vortex pinning force and the corrective pinning force of the BHO-doped SmBCOﬁlm were stronger than those of the BSO-doped SmBCOﬁlm.The higher J c of the BHO-doped SmBCOﬁlm under weakﬁelds may havebeen induced by the higher J selfc .Figure6shows the magneticﬁeld dependence of the macroscopic pinning force(F p)estimated from these J c–B curves at77K under B c.The maximum values of F p reached3.29GN m−3for the pure SmBCOﬁlm,24.5GN m−3Figure7.Irreversibilityﬁeld(B irr)lines for a pure SmBCOﬁlm,a BSO-doped SmBCOﬁlm,and a BHO-doped SmBCOﬁlm in B c.for the BSO-doped SmBCOﬁlm,and28.0GN m−3for the BHO-doped SmBCOﬁlm.Figure7shows the irreversibilityﬁeld(B irr)line with B c for eachﬁlm.In the B irr lines of the BMO-doped SmBCO ﬁlms,the lines discontinuously shifted upward by around1T. Similar discontinuities were reported in earlier studies with heavy-ion irradiation[28,29],BMO nanorods[30],and Au nanorods[31].This is thought to be a common property of the vortex system in REBCOﬁlms with c-axis-correlated pinning centers.B irr for the BHO-doped SmBCOﬁlm was higher than that for the pure SmBCOﬁlm and the BSO-doped SmBCOﬁlm at all temperatures,because the T c for the BHO-doped SmBCO ﬁlm was comparable with the T c for the pure SmBCOﬁlm, and theﬁlm included BHO nanorods.B irr for the BHO-doped SmBCOﬁlm reached15.0T at77K.It is notable that the inclination of the B irr line for the BHO-doped SmBCOﬁlm was different from that for the otherﬁlms under a strong magneticﬁeld.It may be that the pinning properties of the BHO-doped SmBCOﬁlm under a strong magneticﬁeld differ from those of the otherﬁlms,or the corrective pinning force may be substantially stronger than for the otherﬁlms.As mentioned above,the J c–B curves and B irr lines suggest that theﬂux pinning force of the BHO-doped SmBCO ﬁlm was stronger than that of the BSO-doped SmBCOﬁlm, at least with B c.Additionally,in order to clarify the inﬂuence of the nanorod shape and BMO materials on the anisotropicﬂux pinning properties,we measured the magnetic ﬁeld angular dependence of J c for eachﬁlm.Figures8(a)and (b)show the magneticﬁeld angular dependence of J c in1 and3T.Here,we deﬁned the intrinsic pinning peak angle as90◦.Inﬁgure8(a),the BMO-doped SmBCOﬁlms had a J c peak around B c(0◦)in a1Tﬁeld.These peaks arose fromﬂux pinning by the nanorods.1T is below the matching ﬁeld of bothﬁlms,so the entireﬂux quantum should be trapped by the nanorods.The peak of the BHO-doped SmBCO ﬁlm was higher and sharper than that of the BSO-doped SmBCOﬁlm,even though the J c values were nearly the same at other angles.In other words,the single-vortex pinning force of the BHO-doped SmBCOﬁlm was stronger than thatFigure8.Magneticﬁeld angular dependence of J c at77K for a pure SmBCOﬁlm,a BSO-doped SmBCOﬁlm,and a BHO-doped SmBCO ﬁlm under(a)1T and(b)3T.of the BSO-doped SmBCOﬁlm.Also,in a3Tﬁeld,the BMO-doped SmBCOﬁlms had J c peaks around B c,as shown inﬁgure8(b),and J c for the BHO-doped SmBCOﬁlm was higher than that for the BSO-doped SmBCOﬁlm.3T is above the matchingﬁeld for bothﬁlms,so there should be untrappedﬂux quanta in bothﬁlms.In such a case,the pinning force of the nanorods should act not on individualﬂux quanta, but onﬂux bundles.Therefore,theﬂux pinning force of the BHO-doped SmBCOﬁlm on theﬂux bundle was also stronger than that of the BSO-doped SmBCOﬁlm and theﬂux pinning force for a singleﬂux quantum.A comparison of the superconducting properties indicates that the BHO-doped SmBCOﬁlm was superior to the BSO-doped SmBCOﬁlm.Speciﬁcally,J c withB c for the BHO-doped SmBCOﬁlm was higher in both weak and strong magneticﬁelds,and the c-axis correlation of the nanorod ﬂux pinning was stronger according to the magneticﬁeld angular dependence of J c.The superior performance of the BHO nanorods was a result of the linearity and the narrow inclination angle distribution of the nanorods.In a strong magneticﬁeld,theﬂux quanta should penetrate into the REBCO with a straight shape and remain parallel to each other,because their mutual repulsion restricts their bending. In this case,compared to the case of BSO nanorods with a widely distributed inclination angle,theﬂux pinning force acting on theﬂux bundle due to the BHO nanorods should be stronger.In a weakerﬁeld,straighter nanorods should generate a strongerﬂux pinning force when theﬁeld is applied parallel to the nanorods.4.ConclusionWe compared theﬂux pinning properties and microstructures of a BHO-doped SmBCOﬁlm and a BSO-doped SmBCO ﬁlm fabricated on a single-crystal LAO substrate using an alternating-targets method.To simplify this comparison,we kept the diameter the same for both kinds of nanorods by con-trolling the substrate temperature.Speciﬁcally,we deposited the BHO-doped SmBCOﬁlm at higher substrate temperature than the BSO-doped SmBCOﬁlm.In cross-sectional TEM observations and in in-ﬁeld J c measurements,the BHO-doped SmBCOﬁlm with straight nanorods and a narrow distribution of inclination angle generated a strongerﬂux pinning force than the BSO-doped SmBCOﬁlm with a widely distributed nanorod inclination angle under all of the magneticﬁelds examined.From the results of this study,it seems that the superior performance of the BHO-doped SmBCOﬁlm was a result of the linearity and the narrow inclination angle distri-bution of the BHO nanorods.Additionally,the high substrate temperature during deposition would make the introduction of nanorods possible.AcknowledgmentsThis work was supported in part by Grants-in-Aid for Scientiﬁc Research(20686065,19676005,and25289358)and a Grant-in-Aid for JSPS Fellows(25002829).References[1]Larbalestier D,Gurevich A,Feldmann D M and Olyanskii A2001Nature414368[2]Sparing M,Backen E,Freudenberg T,Huhne R,Rellinghaus B,Schultz L and Holzapfel B2007Supercond.Sci.Technol.20239[3]Sueyoshi T,Ishikawa N,Iwase A,Chimi Y,Kiss T,Fujiyoshi T and Miyahara K1998Physica C30979[4]Broussard P R,Cestone V C and Allen H R1995IEEE Trans.Appl.Supercond.51222[5]Roas B,Hensel B,Saemann-Ischenko G and Schultz L1989Appl.Phys.Lett.541051[6]Macmanus J L,Foltyn S R,Jia Q X,Wang H,Serquis A,Civale L,Maiorov B,Hawley M E,Maley M P andPeterson D E2004Nat.Mater.3439[7]Miura M,Kato T,Yoshizumi M,Yamada Y,Izumi T,Shiohara Y and Hirayama T2008Appl.Phys.Express1051701[8]Yamada Y et al2005Appl.Phys.Lett.87132502[9]Mele P,Matsumoto K,Horide T,Ichinose A,Mukaida M,Yoshida Y,Horii S and Kita R2008Supercond.Sci.Technol.21032002[10]Teranishi R,Yasunaga S,Kai H and Yamada K2008PhysicaC4681522[11]Wee S H,Goyal A,Zuev Y L,Cantoni C,Selvamanickam Vand Specht E D2010Appl.Phys.Express3023101 [12]Harrington S A,Durrell J H,Maiorov B,Wang H,Wimbush S C,Kursumovic A,Lee J H andMacManus-Driscoll J L2009Supercond.Sci.Technol.22022001[13]Mele P,Matsumoto K,Ichinose A,Mukaida M,Yoshida Y,Horii S and Kita R2009Physica C4691380[14]Haugan T,Barnes P N,Wheeler R,Meisenkothen F andSumption M2004Nature430867[15]Mele P,Matsumoto K,Horide T,Ichinose A,Mukaida M,Yoshida Y,Horii S and Kita R2008Supercond.Sci.Technol.21015019[16]Harada T,Yoshida Y,Ichino Y,Ozaki T,Takai Y,Matsumoto K,Ichinose A,Horii S,Mukaida M and Kita R2009Physica C4691392[17]Ozaki T,Yoshida Y,Ichino Y,Takai Y,Ichinose A,Matsumoto K,Horii S,Mukaida M and Takano Y2010J.Appl.Phys.10893905[18]Ercolano G,Bianchetti M,Wimbush S C,Harrington S A,Wang H,Lee J H and MacManus-Driscoll J L2011Supercond.Sci.Technol.24095012[19]Tsuruta A,Yoshida Y,Ichino Y,Ichinose A,Matsumoto Kand Awaji S2013Japan.J.Appl.Phys.52010201 [20]Tobita H,Notoh K,Higashikawa K,Inoue M,Kiss T,Kato T,Hirayama T,Yoshizumi M,Izumi T and Shiohara Y2012Supercond.Sci.Technol.25062002[21]Tsuruta A,Yoshida Y,Ichino Y,Ichinose A,Matsumoto Kand Awaji S2013IEEE Trans.Appl.Supercond.238001104[22]Nelson D R and Vinokur V M1993Phys.Rev.B4813060[23]Kai H,Horii S,Ichinose A,Kita R,Matsumoto K,Yoshida Y,Fujiyoshi T,Teranishi R,Mori N and Mukaida M2010Supercond.Sci.Technol.23025017[24]Maiorov B,Baily S A,Zhou H,Ugurlu O,Kennison J A,Dowden P C,Holesinger T G,Foltyn S R and Civale L2009Nat.Mater.8398[25]Gurevich A and Pashitskii E A1997Phys.Rev.B566213[26]Tarascon J M,McKinnon W R,Greene L H,Hull G W andV ogel E M1987Phys.Rev.B36226[27]Fukunaga O and Fujita T1973J.Solid State Chem.8331[28]Sugano R,Onogi T,Hirata K and Tachiki M1998Phys.Rev.Lett.802925[29]Nojima T,Katakura M,Okayasu S,Endo S and Kobayashi N2003J.Low Temp.Phys.131859[30]Horii S et al2007Supercond.Sci.Technol.201115[31]Horide T,Matsumoto K,Ichinose A,Mukaida M,Yoshida Yand Horii S2007Supercond.Sci.Technol.20303。

半导体专业术语英语讲解学习

半导体专业术语英语1. acceptance testing (WAT: wafer acceptance testing)2. acceptor: 受主，如B，掺入Si中需要接受电子3. ACCESS：一个EDA（Engineering Data Analysis）系统4. Acid：酸5. Active device：有源器件，如MOS FET（非线性，可以对信号放大）6. Align mark(key)：对位标记7. Alloy：合金8. Aluminum：铝9. Ammonia：氨水10. Ammonium fluoride：NH4F11. Ammonium hydroxide：NH4OH12. Amorphous silicon：α-Si，非晶硅（不是多晶硅）13. Analog：模拟的14. Angstrom：A（1E-10m）埃15. Anisotropic：各向异性（如POLY ETCH）16. AQL(Acceptance Quality Level)：接受质量标准，在一定采样下，可以95%置信度通过质量标准（不同于可靠性，可靠性要求一定时间后的失效率）17. ARC(Antireflective coating)：抗反射层（用于METAL等层的光刻）18. Antimony(Sb)锑19. Argon(Ar)氩20. Arsenic(As)砷21. Arsenic trioxide(As2O3)三氧化二砷22. Arsine(AsH3)23. Asher：去胶机24. Aspect ration：形貌比（ETCH中的深度、宽度比）25. Autodoping：自搀杂（外延时SUB的浓度高，导致有杂质蒸发到环境中后，又回掺到外延层）26. Back end：后段（CONTACT以后、PCM测试前）27. Baseline：标准流程28. Benchmark：基准29. Bipolar：双极30. Boat：扩散用（石英）舟31. CD：（Critical Dimension）临界（关键）尺寸。

CZTS在快速硫化过程中的相转变

D O I :10.3969/j.i s s n .1001-5337.2023.2.014 *收稿日期:2022-07-08基金项目:山东省泰山学者青年专家计划(t s q n 201909107);国家自然科学基金青年科学基金(62104131);山东省高等学校青年创新团队发展计划(2021K J 022);山东省自然科学基金青年科学基金(Z R 2020Q F 077).通信作者:张永政,男,1988-,博士,教授;研究方向:能量转换材料;E -m a i l :y z z h a n g@q f n u .e d u .c n .C Z T S 在快速硫化过程中的相转变*孔一霖, 殷鸿飞, 马传贺, 张永政(曲阜师范大学物理工程学院,273165,山东省曲阜市) 摘要:首先采用磁控共溅射的方法在镀钼钠钙玻璃上制备了C u -Z n -S n 三元金属预制层,再以硫粉为硫源,用快速退火处理(R T P )炉分别在200ħ㊁250ħ㊁300ħ㊁350ħ㊁400ħ㊁450ħ㊁500ħ㊁550ħ和600ħ进行1h 快速热处理,得到不同温度硫化的薄膜,分别采用X R D ㊁R a m a n ㊁S E M 进行物相和表面形貌的表征.结果表明,在硫化退火过程中,在250~300ħ,首先形成的二元相有C u 2S ㊁Z n S ㊁S n S ;在300~350ħ,三元相C u 2S n S 3形成;超过350ħ时,晶粒尺寸较小的C u 2Z n S n S 4(C Z T S )开始形成;随着温度继续升高,C Z T S 的晶粒逐渐长大,杂相减少;当温度达到500ħ时,表面形成结晶性好㊁晶粒尺寸大且无杂相的C Z T S 薄膜.通过对X R D 和R a m a n 图谱的分析,确立了各个温度区间发生相转变的化学反应方程式.关键词:C Z T S 薄膜;快速热处理;硫化;相变中图分类号:T K 513 文献标识码:A 文章编号:1001-5337(2023)02-0014-050 引言近年来,随着能源需求的持续扩大和环境问题的不断恶化,人类对清洁能源特别是太阳能的开发和利用显得尤为重要.在各种太阳能电池中,基于铜锌锡硫材料(C Z T S )的薄膜电阳能电池近几年来引起了学界和业界的广泛关注[1-4].与铜铟镓硒(C I G S )及碲化镉(C d T e )类似,C Z T S 也是闪锌矿结构演变而来的硫系化合物半导体,它具有很高的吸收系数和合适的禁带宽度,理论效率高达32.4%[5],是理想的单节太阳电池吸收层材料.同时,与C I G S 和C d T e 相比,C Z T S 还有一个独特的优势,即组成这种材料的几种元素(C u :50ˑ10-6,Z n :75ˑ10-6,S n :2.2ˑ10-6,S :260ˑ10-6)都是环境友好型高丰度元素[6].这大大地降低了C Z T S 薄膜太阳能电池的材料成本和环保压力[6],有利于其大规模应用.但经过多年的研究,目前C Z T S 薄膜太阳能电池的最高转换效率只有12.6%[7],与理论效率还有相当大的差距.造成这个结果的最主要的原因是C Z T S 材料在相图中的稳定空间较小.由于四元体系的复杂性,C Z T S 中常常伴随着各种二次杂相,包括Z n S ㊁S n S ㊁S n S 2㊁C u S ㊁C u 2S ㊁C u S 2以及C u 2S n S 3等[8-10].这些杂相的形成条件各不相同,若形成条件得不到有效的控制,C Z T S 由于退火时的温度控制失误而被误分解,易形成气相的S n S 和S n S 2,导致薄膜中的S 和S n 损失,从而使C Z T S 的纯度大大降低[11],因此从实验上得到完全纯净的C Z T S 相难度较大.二次杂相对于C Z T S 材料及其电池性能的影响主要集中在缺陷态和能带结构上,C u 2S n S 3㊁S n S 和C u 2S 这三种杂相,由于禁带宽度低于C Z T S ,将会直接限制开路电压V o c ,导致太阳能转换效率大大降低,因此我们要在热处理过程中避免二次杂相的产生.所以,制备高效率器件的关键,是研究通过硫化退火过程获取单一相的C Z T S 多晶薄膜的方法.本文通过摸索不同退火温度下的物相变化规律,寻找C u 2S ㊁S n S ㊁C u 2S n S 3等有害二次相生成的温度区间,确定硫化退火过程中相的变化,为优化退火工艺和制备大尺寸㊁单一相的C Z T S 锌黄锡矿晶体提供理论基础.第49卷第2期2023年4月曲阜师范大学学报J o u r n a l o f Q u f u N o r m a l U n i v e r s i t yV o l .49 N o .2A p r .2023 Copyright ©博看网. All Rights Reserved.1实验方法以铜锌锡合金靶作为溅射源㊁镀钼的钠钙玻璃为衬底㊁4m T o r r的氩气为保护气体,在室温下采用真空共溅射的方法制备C u-Z n-S n三元金属预制层,溅射功率为80W,溅射时间1h.C u-Z n-S n三元金属预制层成分按照贫铜富锌的比例设定,即C u/Z n+S n=0.85,Z n/S n=1.21;后用R T P炉分别在200ħ㊁250ħ㊁300ħ㊁350ħ㊁400ħ㊁450ħ㊁500ħ㊁550ħ和600ħ进行硫化处理1h.硫粉(纯度:99.99%,A l f aA e s a r)为硫源;30T o r r氩气为保护气体;升温速率设置为500ħ/m i n,以避免在中间温度发生副反应.采用日本岛津X射线衍射仪(X R Dd i f f r a c t o m-e t e rw i t hC uKα,λ=1.5418Å)和激光光源为532 n m的拉曼光谱仪(L a b r a m H R800)对样品的物相进行了分析;采用扫描电子显微镜(日立,S4800型)观察样品表面形貌.2结果与讨论2.1 X R D图谱分析由于C Z T S的在硫化退火过程中,形成的合金相㊁二元硫化物㊁三元硫化物和C Z T S的X R D图谱主峰的2θ角度在25ʎ~40ʎ之间(见图1),所以在不同硫化温度下X R D的2θ只取25ʎ~40ʎ.图1不同温度下制备的C Z T S薄膜X R D衍射图谱分析不同温度下X R D谱图可知,溅射制备的C Z T三元金属合金预制层在30ʎ㊁35ʎ出现X R D衍射峰.经分析可知,这两个衍射峰分别为C u6S n5相(J C P D S#45-1488)和C u5Z n8相(J C P D S#65-7657)特征衍射峰[12-13].200ħ加热硫化处理后,C u5Z n8㊁C u6S n5合金相强度升高.与此同时,在37.4ʎ出现衍射峰,是C u2S(J C P D S#26-1116)(102)特征衍射峰.250ħ硫化处理后,C u5Z n8㊁C u6S n5合金相消失,3种金属元素已被硫化,二元硫化物Z n S (J C P D S#05-0566)的(004)和S n S(J C P D S#65-2610)的(111)衍射峰出现,这与文献报道的一致[14].300ħ硫化退火后,三元相C u2S n S3在28.5ʎ的衍射峰形成,其他二元相峰强度变高[15].升温至350ħ时,二元相S n S消失,同时,在28.4ʎ㊁33.0ʎ出现小峰.分析可知,是四元相C Z T S(J C P D S#26-0575)的(112)(200)晶面的衍射峰[16].但X R D谱图中还有Z n S㊁C u2S相.到400ħ时,C Z T S四元相强度升高,但X R D谱图中还有Z n S,C u2S二元杂相. 450ħ硫化退火后,得到结晶性好,无杂相的C Z T S 薄膜.结合不同温度下的X R D谱图分析可知,共溅射的金属预制层在室温下主要含有C u5Z n8相和C u6S n5相.200ħ是C u2S相形成的温度;250~ 400ħ是二元相㊁三元相㊁四元相形成㊁相互转化的温度区间.在这个温度区间内,复杂的化学反应在发生,是C Z T S成相过程中的一个重要的温度区间,需重点研究.但是Z n S㊁C u2S n S3㊁C Z T S的X R D曲线很接近[17],主峰可能出现重叠现象,为了更好的研究,我们对样品做了激光器光源为532n m的拉曼测试(见图2).图2不同温度下制备的C Z T S薄膜表面R a m a n图谱51第2期孔一霖,等:C Z T S在快速硫化过程中的相转变Copyright©博看网. All Rights Reserved.2.2 R a m a n图谱分析分析图2可知,预制层没有拉曼峰.200ħ硫化退火时,拉曼图谱在475c m-1处出现一个明显的峰,是二元相C u2-x S形成的拉曼峰[18-20],随着温度的升高C u2-x S的峰强度逐渐变小.于此同时,温度升高至250ħ时,在219c m-1处出现小峰,根据文献报道,为二元硫化物S n S的特征拉曼峰,当温度达到350ħ的时候S n S拉曼峰消失[21-22].300ħ时,三元相C u2S n S3相位于303c m-1的拉曼特征峰被检测到,温度升至350ħ时,四元化合物C Z T S形成,但伴有少量C u2-x S杂相.当温度升高至500ħ时,形成单一无杂相的C Z T S化合物.由532n m激光拉曼测试分析得到的结果与X R D结果一致.图3不同温度下制备的C Z T S薄膜表面形貌S E M 2.3 C Z T S表面形貌分析分析表面S E M电镜照片可知,200ħ硫化退火后,薄膜表面由50~100n m的小晶粒组成.当温度升高到250ħ时,薄膜表面出现了一些块状晶体.通过X R D和表面拉曼测试可知,这些块状晶体为C u2S.300ħ时,薄膜表面被晶粒尺寸小的晶体覆盖.随着温度继续升高,通过X R D和拉曼测试表面,C Z T S开始形成.350~450ħ时,薄膜表面的C Z T S晶粒尺寸小,并有更小尺寸的颗粒晶体在薄膜表面.当温度升高至500ħ时,薄膜表面形成结晶性好,晶粒尺寸大于1μm的C Z T S晶体,杂相小晶粒也同时消失.但温度升高到600ħ后,C Z T S晶粒边缘出现熔融现象,晶界处界面不明显.通过X R D,R a m a n分析,在C u-Z n-S n三元金属预制层退火过程中,在各个温度区间内,主要发生以下化学反应.形成二元硫化物的化学反应方程式及温度区间,(C u Z na l l o y,C u S na l l o y)+S(g)ңC u2S+Z n S+S n S,250~300ħ.形成三元硫化物的化学反应方程式及温度区间,C u2S+S n S+S(g)ңC u2S n S3,300~350ħ.形成四元硫化物的化学反应方程式及温度区间,C u2S+Z n S+S n S+SңC u2Z n S n S4,C u2S n S3+Z n SңC u2Z n S n S4,ȡ350ħ.由于C Z T S相和Z n S相在结构上非常接近,加之Z n含量往往高于C Z T S的计量比,所以在硫化过程中更应该避免Z n S的产生.基于S i g m u n d溅射理论和B o r n-H a b e r循环可知,C Z T S相的生成焓为-930k J㊃m o l-1,Z n S相的生成焓为-206k J㊃m o l-1[23],因此在较低硫化温度下Z n S相比较容易生成.为了得到纯相C Z T S,我们必须提高升温速度,在短时间内将温度提升至350ħ以上,达到C Z T S的形成温度范围,从而减少中间二次杂相Z n S的形成.3结论本文通过对200ħ㊁250ħ㊁300ħ㊁350ħ㊁400ħ㊁450ħ㊁500ħ㊁550ħ和600ħ快速硫化退火处理的C Z T S薄膜进行研究发现,在硫化过程中,主要形成的二元相有C u2S㊁Z n S㊁S n S,它们的形成温度在250~300ħ.而硫化退火过程中的三元相C u2S n S3在300~350ħ形成.超过350ħ时,小晶粒的C Z T S开始形成,温度继续升高,C Z T S晶粒逐渐长大,杂相减少;当温度达到500ħ时,表面形成结晶性好㊁晶粒尺寸大且无杂相的C Z T S薄膜.因此,采用快速升温硫化处理工艺可以提高C Z T S薄膜质量,有效避免中间二次杂相的产生,为获得高性能C Z T S薄膜太阳能电池提供实验参考.参考文献:[1]I T O K,N A K A Z AWA T.E l e c t r i c a l a n do p t i c a l p r o p e r-t i e s o f s t a n n i t e-t y p e q u a t e r n a r y s e m i c o n d u c t o r t h i n f i l m s [J].J a p a n e s e J o u r n a lo f A p p l i e d P h y s i c s,1988,27(11):2094-2097.61曲阜师范大学学报(自然科学版)2023年Copyright©博看网. All Rights Reserved.[2]Z Y O U N DS H,Z Y O U N D A H,A HM E D N M,e ta l. N u m e r i c a lm o d e l i n g o f h i g hc o n v e r s i o ne f f i c i e n c y F T O/ Z n O/C d S/C Z T S/MOt h i nf i l m-b a s e ds o l a rc e l l s:u s i n g S C A P S-1Ds o f t w a r e[J].C r y s t a l s,2021,11(12):1468.[3]MA Z UM D E RS,S E N T H I K UMA RK.D e v i c e s t u d y a n d o p t i m i s a t i o no f C Z T S/Z n Sb a s e d s o l a r c e l l w i t hC u I h o l e t r a n s p o r t l a y e r f o rd i f f e r e n t c o n d u c t i o nb a n do f f s e t[J]. S o l a rE n e r g y,2022,237:414-431.[4]B E H E R A N,MOHA NDB.I n v e s t i g a t i o n o f b r o a d-b a n d o p t i c a la b s o r p t i o na n de l e c t r i c a l p r o p e r t i e si n v a c u u m a n n e a l e d C Z T S/A g m u l t i-l a y e r e d s t a c k s t r u c t u r e f o r p l a s m o n i cs o l a rc e l la p p l i c a t i o n[J].O p t i c a l M a t e r i a l s, 2022,127:112316.[5]K I W,H I L L HO U S E H W.E a r t h-a b u n d a n te l e m e n t p h o t o v o l t a i c s d i r e c t l y f r o ms o l u b l e p r e c u r s o r sw i t hh i g h y i e l du s i n g an o n-t o x i cs o l v e n t[J].A d v a n c e d E n e r g yM a t e r i a l s,2011,1(5):732-735.[6]L E D O N N E A,T R I C I A L E T T IV,B I N E T T IS.N e we a r t h-a b u n d a n t t h i nf i l m s o l a rc e l l sb a s e d o nc h a l c o-g e n i d e s[J].F r o n t i e r s i nC h e m i s t r y,2019,7:297.[7]P R A B HUS,P A N D E YSK,C HA K R A B A R T I S.I n n o-v a t i v e s t r u c t u r a l e n g i n e e r i n g o f s u s t a i n a b l e a n d e n v i r o n-m e n t-f r i e n d l y C u2Z n S n S4s o l a r c e l l f o r o v e r20%c o n v e r-s i o ne f f i c i e n c y[J].I n t e r n a t i o n a l J o u r n a lo fE n e r g y R e-s e a r c h,2022,46(11):15300-15308.[8]WA N G W,W I N K L E R M T,G U N AWA N O,e t a l.D e-v i c e c h a r a c t e r i s t i c s o fC Z T S S e t h i n-f i l ms o l a r c e l l sw i t h 12.6%e f f i c i e n c y[J].A d v a n c e dE n e r g y M a t e r i a l s,2014, 4(7):1301465.[9]I N D U B A L A E,S A R V E S HV A R A N S,S U D HA V,e ta l.S e c o n d a r yp h a s e s a n d t e m p e r a t u r e e f f e c t o n t h e s y n-t h e s i sa n d s u l f u r i z a t i o n o f C Z T S[J].S o l a r E n e r g y, 2018,173:215-224.[10]Z HA N G Y M,J I AZJ,Z HA OZY.S e c o n d a r yp h a s e si nC u2Z n S n S4t h i n f i l ms o l a r c e l l:t h e r o l eo f i n t e r f a c e s[J].P h i s i c sB:C o n d e n s e d M a t t e r,2022,626:413539.[11]E R HA N S,Y A GM R O V A,A L T UM T E P E A,e ta l.I n t e g r a t i o no fs i n g l el a y e r g r a p h e n ei n t o C Z T St h i nf i l m s o l a r c e l l s[J].J o u r n a lo f A l l o y d s a n d C o m-p o u n d s,2022,920:166041.[12]X I A N G D M,Z HA O A M,L IB,e t a l.E l e c t r o d e p o s i-t i o na s s i s t e d s o l-g e l p r o c e s s t o p r e p a r eC Z T S t h i n f i l m s[J].M a t e r i a l sS c i e n c ei n S e m i c o n d u c t o rP r o c e s s i n g, 2022,148:106784.[13]K A N S A N P K,C H A U D H A R YS,D E YSR.I m p a c to fs u l p h u r i z a t i o ne n v i r o n m e n to nf o r m a t i o n o f C u2Z n S n S4f i l m s u s i ng e l e c t r o n b e a me v a p o r a t e d s t a c k e dm e t a l l i c p r e-c u r s o r s[J].B u l l s t i n o fM a t e r i a l s S c i e n c e,2019,42:11.[14]MOH S S E N I M,A R A M H M,D E H G HA N I M.D e-t e r m i n a t i o no fc r i t i c a l t o t a l s e c o n d a r yp h a s ed e n s i t i e si nC Z T Sa n d i n v e s t i g a t i o no f t h e i re f f e c t so nt h e p e r-o v s k i t e s o l a r c e l l p e r f o r m a n c ew i t hC Z T Sa sa n H T L[J].O p t i c a lM a t e r i a l s,2022,128:112453.[15]S C R A G GJ J,E R I C S O N T,F O N T A NéX,e t a l.R a p i da n n e a l i n g o f r e a c t i v e l y s p u t t e r e d p r e c u r s o r s f o rC u2Z n S n S4s o l a rc e l l s[J].P r o g r e s si nP h o t o v o l t a i c s:R e s e a r c ha n dA p p l i c a t i o n s,2014,22(1):10-17. [16]A K C A Y N,A T A S E R T,O Z E N Y,e t a l.I n f l u e n c eo fs u l f u r i z a t i o n t i m e o nt h e p r o p e r t i e so fC u2Z n S n S4t h i nf i l m sd e p o s i t e d o n M o-c o a t e d s o d al i m eg l a s s s u b-s t r a t e s b y C o-s p u t t e r i n g t e c h n i q u e[J].T h i n S o l i dF i l m s,2020,704:138028.[17]WA N GT,Z HA N GJY,Y A OB,e t a l.I n f l u e n c em e c h-a n i s mo fC u+/(C u++C u2+)r a t i o i nC u-Z n-S n-S p r e-c u r s o r s o l u t i o n o n p e r f o r m a n c e o f C u2Z n S n(S,S e)4s o-l a r c e l l s[J].S o l a rE n e r g y,2022,231:775-783. [18]Z A K IM Y,E IK HO U J A O,N O U N E H K,e t a l.Z n Ss t a c k i n g o r d e r i n f l u e n c eo nt h ef o r m a t i o no fZ n p o o ra n dZ n-r i c hC u2Z n S n S4p h a s e[J].J o u r n a l o fM a t e r i a l sS c i e n c e-M a t e r i a l s i nE l e c t r o n i c s,2022,33(15):11989-12001.[19]C H R I S T I N A LR A S,P R A K A S HI,C HA K R A V A R-T YS,e t a l.S p r a yp y r o l y s e dC u2Z n S n S4t h i n f i l m p h o-t o v o l t a i cc e l l f a b r i c a t e du s i n g c o s te f f e c t i v e m a t e r i a l s[J].P h y s i c a B:P h y s i c so fC o n d e n s e d M a t t e r,2022, 637:413911.[20]S E L V S H C H E V O,HA V R Y L I U K Y,V A L A K H MY,e t a l.R a m a n a n dX-r a y p h o t o e m i s s i o n i d e n t i f i c a t i o no f c o l l o i d a lm e t a l s u l f i d e sa s p o t e n t i a l s e c o n d a r yp h a-s e s i nn a n o c r y s t a l l i n eC u2Z n S n S4p h o t o v o l t a i c a b s o r b-e r s[J].A C S A p p l i e d N a n o M a t e r i a l s,2020,3(6):5706-5717.[21]E IMA H B O U BE,E IH I C HO U A,MA N S O R IM.An o n t o x i ca n dl o w-c o s ts o l u t i o n-p r o c e s s e d C Z T S a b-s o r b e r l a y e r f o r s o l a r p h o t o v o l t a i c a p p l i c a t i o n s:s o l v e n te f f e c t s o nt h e p h y s i c a l p r o p e r t i e s[J].P h y s i c aS t a t u sS o l i d iA-A p p l i c a t i o n sa n d M a t e r i a l sS c i e n c e,2022,219(10):2100882.[22]Z I T IA,HHA R T I T IB,L A B R I M H,e ta l.D e v e l o p-m e n t o f d i p-c o a t e dC u2Z n S n S4a b s o r b e rm a t e r i a lw i t h-o u t s u l p h u r i s a t i o n[J].J o u r n a lo fS o l-g e lS c i e n c ea n dT e c h n o l o g y,2021,99(1):252-262.[23]B A R Y S H E VSV,T H I M S E N E.E n t h a l p y o f f o r m a t i o nf o rC u-Z n-S n-S(C Z T S)c a l c u l a t e df r o ms u r f a c eb i n d i n ge n e r g i e se x p e r i m e n t a l l y m e a s u r e db y i o ns p u t t e r i n g[J].C h e m i s t r y o fM a t e r i a l s,2015,27(7):2294-2298.71第2期孔一霖,等:C Z T S在快速硫化过程中的相转变Copyright©博看网. All Rights Reserved.81曲阜师范大学学报(自然科学版)2023年I n v e s t i g a t i o no fC Z T S p h a s e f o r m a t i o nb y r a p i d t h e r m a l p r o c e s sK O N GY i l i n,Y I N H o n g f e i,MAC h u a n h e,Z HA N GY o n g z h e n g(S c h o o l o f P h y s i c s a n dP h y s i c a l E n g i n e e r i n g,Q u f uN o r m a lU n i v e r s i t y,273165,Q u f u,S h a n d o n g,P R C)A b s t r a c t:C u-Z n-S n p r e c u r s o rw a s p r e p a r e db y c o-s p u t t e r i n g m e t h o do n m o l y b d e n u m-c o a t e ds o d i u m c a l c i u m g l a s s.A n d t h e n s u l f u r p o w d e rw a s u s e d a s s u l f u r s o u r c e d u r i n g r a p i d a n n e a l i n g t r e a t m e n t p r o c e s s (R T P)a p p l i e d a t200ħ,250ħ,300ħ,350ħ,400ħ,450ħ,500ħ,550ħa n d600ħ,r e s p e c t i v e l y,f o r 1h o u rt oo b t a i n C u2Z n S n S4(C Z T S)f i l m s.T h e p h a s e sa n ds u r f a c e m o r p h o l o g i e sw e r ec h a r a c t e r i z e db y X R D,R a m a na n dS E M.T h e r e s u l t s s h o wt h a tC u2S,Z n Sa n dS n Sb i n a r yp h a s e s a r e f i r s t l y f o r m e d250~ 300ħ.T h e t e r n a r yp h a s eC u2S n S3i s f o r m e d a t300~350ħ.O v e r350ħ,C Z T Sw i t h s m a l l g r a i n s i z e b e-g a n t o f o r m.W i t h t h e i n c r e a s i n g o f t e m p e r a t u r e,t h e g r a i n s i z e o f C Z T S g r e wu p g r a d u a l l y a n d t h e s e c o n d a-r yp h a s e s d e c r e a s e d.W h e n t h e t e m p e r a t u r e r e a c h e s500ħ,C Z T S f i l m sw i t h l a r g e g r a i ns i z e a n dw i t h o u t s e c o n d a r yp h a s e sa r ef o r m e do nt h es u r f a c ea n di nt h eb u l k.B y X R Da n d R a m a ns p e c t r aa n a l y s i s,t h e c h e m i c a l r e a c t i o ne q u a t i o n s o f p h a s e t r a n s i t i o nd u r i n g e a c h t e m p e r a t u r e r a n g e a r e e s t a b l i s h e d.K e y w o r d s:C Z T S f i l m;R T P;s u l f u r i z a t i o n;p h a s e f o r m a t i o nCopyright©博看网. 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Intelligent Transport(智能交通)英文和翻译

湖南科技大学智能控制理论论文姓名：_____________ 学院：_____________ 班级：_____________ 学号：_____________Intelligent Traffic Signal Control Using Wireless SensorNetworksAbstractThe growing vehicle population in all developing and developed countries calls for a major change in the existing traffic signaling systems. The most widely used automated system uses simple timer based operation which is inefficient for non-uniform traffic. Adv anced automated systems in testing use image processing techniques or advanced com munication systems in vehicles to communicate with signals and ask for routing. This mig ht not be implementable in developing countries as they prove to be complex and expens ive. The concept proposed in this paper involves use of wireless sensor networks to sens e presence of traffic near junctions and hence route the traffic based on traffic density in t he desired direction. This system does not require any system in vehicles so can be impl emented in any traffic system easily. This system uses wireless sensor networks technol ogy to sense vehicles and a microcontroller based routing algorithm for traffic managem ent.Keywords:Intelligent traffic signals, intelligent routing, smart signals, wireless sensornetworks.INTRODUCTIONThe traffic density is escalating at an alarming rate in developing countries which c alls for the need of intelligent traffic signals to replace the conventional manual and timer based systems. Experimental systems in existence involve image processing based dens ity identification for routing of traffic which might be inefficient in situations like fog, rain or dust. The other conceptual system which is based on interaction of vehicles with traffic si gnals and each other require hardware modification on each vehicle and cannot be practi cally implemented in countries like India which have almost 100 million vehicles on road[1]. The system proposed here involves localized traffic routing for each intersection based on wireless sensor networks. The proposed system has a central controller at every jun ction which receives data from tiny wireless sensor nodes placed on the road. The sensor nodeshave sensors that can detect the presence of vehicle and the transmitter wirelessly trans mits the traffic density to the central controller. The controller makes use of the proposed algorithm to find ways to regulate traffic efficiently.THE NEED FOR AN ALTERNATE SYSTEMThe most prevalent traffic signaling system in developing countries is the timer based system. This system involves a predefined time setting for each road at an int ersection. While this might prove effective for light traffic, heavy traffic requires an adaptiv e system that will work based on the density of traffic on each road. The first system prop osed for adaptive signaling was based on digital image processing techniques. This syste m works based on the captured visual input from the roads and processing them to find w hich road has dense traffic. This system fails during environmental interaction like rain or fog. Also this system in testing does not prove efficient. The advanced system in testing a t Pittsburgh [2] involves signals communicating with each other and also with the vehicles . The proposed system does not require a network between signals and vehicles and is a standalone system at each intersection.THE PROPOSED SYSTEMThis paper presents the concept of intelligent traffic routing using wireless sensor networks. The primary elements of this system are the sensor nodes or motes consi sting of sensors and a transmitter. The sensors interact with the physical environment while the transmitter pages the sensor’s data to the central controller. This system involves t he 4 x 2 array of sensor nodes in each road. This signifies 4 levels of traffic and 2 lanes i n each road. The sensors are ultrasonic or IR based optical sensors which transmits stat us based on presence of vehicle near it. The sensor nodes transmit at specified time inter vals via ZigBee protocol to the central controller placed at every intersection. The controll er receives the signal and computes which road and which lane has to be given green sig nal based on the density of traffic. The controller makes use of the discussed algorithm to perform the intelligent traffic routing.COMPONENTS INVOLVED IN THE SYSTEMThe proposed system involves wireless sensor networks which are comprised of t hree basic components: the sensor nodes or motes, power source and a central controlle r. The motes in turn are comprised of Sensors and transceiver module. The sensors sens e the vehicles at intersections and transceiver transmit the sensor’s data to the central co ntroller through a wireless medium. The Power source provides the power needed for the sensor nodes and is mostly regenerative. The central controller performs all the computa tions for the sensor networks. The controller receives the input from all sensors and proc esses simultaneously to make the required decisions.A.SensorsSensors are hardware devices that produce a measurable response to a change in a physical condition like temperature or pressure. Sensors measure physical data of the parameter to be monitored. The continual analog signal produced by the sensors is digitized by an analog-to-digital converter and sent to controllers for further processing. A sen sor node should be small in size, consume extremely low energy, operate in high volumet ric densities, be autonomous and operate unattended, and be adaptive to the environme nt. As wireless sensor nodes are typically very small electronic devices, they can only be equipped with a limited power source of less than 0.5-2 ampere-hour and 1.2-3.7 volts. S ensors are classified into three categories: passive Omni-directional sensors; passive nar row-beam sensors; and active sensors [3].The sensors are implemented in this system placed beneath the roads in an intersec tion or on the lane dividers on each road. The sensors are active obstacle detectors that detect the presence of vehicles in their vicinity. The sensors are set in four levels on each road signifying four levels of traffic from starting from the STOP line. The fourth level indi cates high density traffic and signifies higher priority for the road to the controller. The se nsors required for obstacle detection can be either ultrasonic or Infrared LASER based s ensors for better higher efficiency.B. MotesA mote, also known as a sensor node is a node in a wireless sensor network that i s capable of performing some processing, gathering sensory information and communica ting with other connected nodes in the network. The main components of a sensor node are a microcontroller, transceiver, external memory, power source and one or more sens ors [3].C. Need for MotesThe primary responsibility of a Mote is to collect information from the various distrib uted sensors in any area and to transmit the collected information to the central controller for processing. Any type of sensors can be incorporated with these Motes based on the r equirements. It is a completely new paradigm for distributed sensing and it opens up a fa scinating new way to look at sensor networks.D. Advantages of MotesThe core of a mote is a small, low-cost, low-power controller.The controller monitors one or more sensors. It is easy to interface all sorts of sensors, including sensors for temperature, light, sound, position, acceleration, vibrat ion, stress, weight, pressure, humidity, etc. with the mote.The controller connects to the central controller with a radio link. The most comm on radio links allow a mote to transmit at a distance of about 3 to 61 meters. Power cons umption, size and cost are the barriers to longer distances. Since a fundamental concept with motes is tiny size and associated tiny cost, small and low-power radios are normal.As motes shrink in size and power consumption, it is possible to imagine solar power or even something exotic like vibration power to keep them running. It is hard to imagine something as small and innocuous as a mote sparking a revolution, but that's exactly what they have done.Motes are also easy to program, either by using serial or Ethernet cable to conne ctto the programming board or by using Over the Air Programming (OTAP).E. TransceiversSensor nodes often make use of ISM band, which gives free radio, spectrum allocation and global availability. The possible choices of wireless transmission medi a are radio frequency (RF), optical communication and infrared. Lasers require less ener gy, but need line-of-sight for communication and are sensitive to atmospheric conditions. Infrared, like lasers, needs no antenna but it is limited in its broadcasting capacity. Radiofrequency-based communication is the most relevant that fits most ofthe WSN applications. WSNs tend to use license-free communication frequencies: 173, 4 33, 868, and 915 MHz; and 2.4 GHz. The functionality of bothtransmitter and receiver are combined into a single deviceknown as a transceiver [3].To bring about uniqueness in transmitting and receiving toany particular device vari ous protocols/algorithms are devised. The Motes are often are often provided with powerf ul transmitters and receivers collectively known as transceivers for better long range oper ation and also toachieve better quality of transmission/reception in any environmental co nditions.F. Power SourceThe sensor node consumes power for sensing, communicating and dataprocessing. More energy is required for data communication than any other process. Power is stored either in batteries or capacitors. Batteries, both rechargeable and non-re chargeable, are the main source of power supply for sensor nodes. Current sensors are able to renew their energy from solar sources, temperature differences, or vibration. Two power saving policies used are Dynamic Power Management (DPM) and Dynamic Voltag e Scaling (DVS). DPM conserves power by shutting down parts of the sensor node which are not currently used or active. A DVS scheme varies the power levels within the senso r node depending on the non-deterministic workload. By varying the voltage along with th e frequency, it is possible to obtain quadratic reduction in power consumption.G. Tmote SkyTmote Sky is an ultra low power wireless module for use in sensor networks,monitoring applications, and rapid application prototyping. Tmote Sky leverages indu stry standards like USB and IEEE802.15.4 to interoperate seamlessly with other devices. By using industry standards, integrating humidity, temperature, and light sensors, and pr oviding flexible interconnection with peripherals, Tmote Sky enables a wide range of mes h network applications [4]. The TMote is one of the most commonly used motes in wirele ss sensor technology. Any type of sensor can be used in combination with this type of mo te.Tmote Sky features the Chipcon CC2420 radio for wireless communications. The CC2420 is an IEEE 802.15.4 compliant radio providing the PHY and some MAC function s [5]. With sensitivity exceeding the IEEE 802.15.4 specification and low power operation, the CC2420 provides reliable wireless communication. The CC2420 is highly configurabl e for many applications with the default radio settings providing IEEE 802.15.4 complianc e. ZigBee specifications can be implemented using the built-in wireless transmitter in the Tmote Sky.H. Tmote Key Features• 250kbps 2.4GHz IEEE 802.15.4 Chipcon Wireless Transceiver• Interoperability with other IEEE 802.15.4 devices.• 8MHz Texas Instruments MSP430 microcontroller (10k RAM, 48k Flash Memory) • Integrated ADC, DAC, Supply Voltage Supervisor, and DMA Controller • Integrate d onboard antenna with 50m range indoors / 125m range outdoors • Integrated Humidity , Temperature, and Light sensors • Ultra low current consumption • Fast wakeup fromsleep (<6μs)• Hardware link-layer encryption and authentication • Programming and data collec tion via USB• 16-pin expansion support and optional SMA antenna connector• TinyOS support : mesh networking and communication implementation • Compli es with FCC Part 15 and Industry Canada regulations • Environmentally friendly – compl ies with RoHS regulations [4].I. ZigBee Wireless TechnologyZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802.15.4 standard for personal ar ea networks [6] [7]. ZigBee devices are often used in mesh network form to transmit data over longer distances, passing data through intermediate devices to reach more distant o nes.This allows ZigBee networks to be formed ad-hoc, with no centralized control or high -power transmitter/receiver able to reach all of the devices. Any ZigBee device can be tas ked with running the network. ZigBee is targeted at applications that require a low data ra te, long battery life, and secure networking. ZigBee has a defined rate of 250kbps, best s uited for periodic or intermittent data or a single signal transmissionfrom a sensor or input device. Applications include wireless light switches, electrical meters with in-home-displays, traffic management systems, and other consumer and ind ustrial equipment that requires short-range wireless transfer of data at relatively low rates . The technology defined by the ZigBee specification is intended to be simpler and less e xpensive than other WPANs, such as Bluetooth.J. Types of ZigBee Devices ZigBee devices are of three types:ZigBee Coordinator (ZC): The most capable device, the Coordinator forms the root of the network tree and might bridge to other networks. There is exactly one Zig Bee Coordinator in each network since it is the device that started the network originally. It stores information about the network, including acting as the Trust Center & repository for security keys. The ZigBee Coordinator the central controller is in this system.ZigBee Router (ZR): In addition to running an application function, a device can act as an intermediate router, passing on data from other devices.ZigBee End Device (ZED): It contains just enough functionality to talk to theparent node. It cannot relay data from other devices. This relationship allows the no de to be asleep a significant amount of the time thereby giving long battery life. A ZED re quires the least amount of memory, and therefore can be less expensive to manufacture t han a ZR or ZC.K. ZigBee ProtocolsThe protocols build on recent algorithmic research to automatically construct a low-s peed ad-hoc network of nodes. In most large network instances, the network will be a clu ster of clusters. It can also form a mesh or a single cluster. The current ZigBee protocols support beacon and non-beacon enabled networks. In non-beacon-enabled networks, an un-slotted CSMA/CA channel access mechanism is used. In this type of network, ZigBee Routers typically have their receivers continuously active, requiring a more robust power supply. However, this allows for heterogeneous networks in which some devices receive continuously, while others only transmit when an external stimulus is detected. In beacon-enabled networks, the special network nodes called ZigBee Routers transmit periodic be acons to confirm their presence to other network nodes. Nodes may sleep between beac ons, thus lowering their duty cycle and extending their battery life. Beacon intervals depe nd on data rate; they may range from 15.36ms to 251.65824s at 250 kbps. In general, th e ZigBee protocols minimize the time the radio is on, so as to reduce power use. In beac oning networks, nodes only need to be active while a beacon is being transmitted. In non -beacon-enabled networks, power consumption is decidedly asymmetrical: some devices are always active, while others spend most of their time sleeping.V. PROPOSED ALGORITHM A. Basic AlgorithmConsider a left side driving system (followed in UK, Australia, India, Malaysia and 72 other countries). This system can be modified for right side driving system (USA, Canada , UAE, Russia etc.) quite easily. Also consider a junction of four roads numbered as node 1, 2, 3 and 4 respectively. Traffic flows from each node to three other nodes with varied densities. Consider road 1 now given green signal in all directions.1)Free left turn for all roads (free right for right side driving system).2)Check densities at all other nodes and retrieve data from strip sensors.3) Compare the data and compute the highest density.4) Allow the node with highest density for 60sec.5)Allowed node waits for 1 time slot for its turn again and the process is repeated f rom step 3.B. Advanced AlgorithmAssume road three is currently given green to all directions. All left turns are always f ree. No signals/sensors for left lane. Each road is given a time slot of maximum 60 secon ds at a time. This time can be varied depending on the situation of implementation. Consi der 4 levels of sensors Ax, Bx, Cx, Dx with A having highest priority and x representing roads 1 to 4. Also consider 3 lanes of traffic: Left (L), Middle (M) and Right(R) correspondin g to the direction of traffic. Since leftturn is free, Left lanes do not require sensors. So sensors form 4x2 arrays with 4 levels of traffic and 2 lanes and are named MAx, RAx, MBx, RBx and so on and totally 32 sensor s are employed.The following flow represents the sequence of operation done by the sign al.1) Each sensor transmits the status periodically to the controller. 2) Controller recei ves the signals and computes the following3) The sensors Ax from each road having highest priority are compared. 4) If a sin gle road has traffic till Ax, it is given green signal in the next time slot. 5) If multiple road s have traffic till Ax, the road waiting for the longest duration is given the green.6) Once a road is given green, its waiting time is reset and its sensor status is negle cted for that time slot7) If traffic in middle lane, green is given for straight direction, based on traffic, either right side neighbor is given green for right direction, of opposite road is give green for str aight direction.8) If traffic in right lane, green is given for right, and based on traffic, left side neighb or is given green for straight or opposite is given green for right.9) Similar smart decisions are incorporated in the signal based on traffic density and directional traffic can be controlled.C. Implementation and RestrictionsThis system can be implemented by just placing the sensor nodes beneath the road or on lane divider and interfacing the central controller to the existing signal lights and co nnecting the sensor nodes to the controller via the proposed wireless protocol. The only r estriction for implementing the system is taking the pedestrians into consideration. This h as to be visualized for junctions with heavy traffic such as highway intersections and amo unt of pedestrians is very less. Also major intersections have underground or overhead fo otpaths to avoid interaction of pedestrians with heavy traffic.ACKNOWLEDGMENTThe Authors would like to take this opportunity to thank Ms. P. Sasikala, Assistant Pr ofessor, ECE department, Sri Venkateswara College of Engineering, Sriperumbudur, wh o gave the basic insight into the field of Wireless Sensor Networks. We also thank Mrs. G . Padmavathi, Associate Professor, ECE department, Sri Venkateswara College of Engin eering, Sriperumbudur, who with her expertise in the field of networks advised and guide d on practicality of the concept and provided helpful ideas for future modifications. We als o express our gratitude to Dr. S. Ganesh Vaidyanathan, Head of the department of ECE, Sri Venkateswara College of Engineering, Sriperumbudur, who supports us for every inn ovative project and encourages us “think beyond” for better use of technology. And finall y we express our heart filled gratitude to Sri Venkateswara College of Engineering, which has been the knowledge house for our education and introduced us to the field of Engine ering and supports us for working on various academic projects.Adaptive urban traffic controlAdaptive signal control systems must have a capability to optimise the traffic flow by adjusting the traffic signals based on current traffic. All used traffic signal control methods are based on feed-back algorithms using traffic demand data -varying from years to a co uple of minutes - in the past. Current adaptive systems often operate on the basis of ada ptive green phases and flexible co-ordination in (sub)networks based on measured traffic conditions (e.g., UTOPIA-spot,SCOOT). These methods are still not optimal where traffic demand changes rapidly within a short time interval. The basic premise is that existing si gnal plan generation tools make rational decisions about signal plans under varying condi tions; but almost none of the current available tools behave pro-actively or have meta-rul es that may change behaviour of the controller incorporated into the system. The next log ical step for traffic control is the inclusion of these meta-rules and pro active and goal-orie nted behaviour. The key aspects of improved control, for which contributions from artificia l intelligence and artificial intelligent agents can be expected, include the capability of dea ling with conflicting objectives; the capability of making pro-active decisions on the basis of temporal analysis; the ability of managing, learning, self adjusting and responding to n on-recurrent and unexpected events (Ambrosino et al.., 1994).What are intelligent agentsAgent technology is a new concept within the artificial intelligence (AI). The agent pa radigm in AI is based upon the notion of reactive, autonomous, internally-motivated entiti es that inhabit dynamic, not necessarily fully predictable environments (Weiss, 1999). Aut onomy is the ability to function as an independent unit over an extended period of time, performing a variety of actions necessary to achieve pre-designated objectives while respo nding to stimuli produced by integrally contained sensors (Ziegler, 1990). Multi-Agent Sys tems can be characterised by the interaction of many agents trying to solve a variety of pr oblems in a co-operative fashion. Besides AI, intelligent agents should have some additio nal attributes to solve problems by itself in real-time; understand information; have goals and intentions; draw distinctions between situations; generalise; synthesise new concept s and / or ideas; model the world they operate in and plan and predict consequences of a ctions and evaluate alternatives. The problem solving component of an intelligent agent c an be a rule-based system but can also be a neural network or a fuzzy expert system. It may be obvious that finding a feasible solution is a necessity for an agent. Often local opt ima in decentralised systems, are not the global optimum. This problem is not easily solv ed. The solution has to be found by tailoring the interaction mechanism or to have a supe rvising agent co-ordinating the optimisation process of the other agents.Intelligent agents in UTC,a helpful paradigmAgent technology is applicable in different fields within UTC. The ones most importa nt mentioning are: information agents, agents for traffic simulation and traffic control. Curr ently, most applications of intelligent agents are information agents. They collect informati on via a network. With special designed agents user specific information can be provided . In urban traffic these intelligent agents are useable in delivering information about weath er, traffic jams, public transport, route closures, best routes, etc. to the user via a Person al Travel Assistant. Agent technology can also be used for aggregating data for further di stribution. Agents and multi agent systems are capable of simulating complex systems for traffic simulation. These systems often use one agent for every traffic participant (in a si milar way as object oriented programs often use objects). The application of agents in (Ur ban) Traffic Control is the one that has our prime interest. Here we ultimately want to use agents for pro-active traffic light control with on-line optimisation. Signal plans then will be determined based on predicted and measured detector data and will be tuned with adjoi ning agents. The most promising aspects of agent technology, the flexibility and pro-activ e behaviour, give UTC the possibility of better anticipation of traffic. Current UTC is not th at flexible, it is unable to adjust itself if situations change and can't handle un-programme d situations. Agent technology can also be implemented on several different control layer s. This gives the advantage of being close to current UTC while leaving considerable free dom at the lower (intersection) level.Designing agent based urban traffic control systemsThe ideal system that we strive for is a traffic control system that is based on actuate d traffic controllers and is able to pro actively handle traffic situations and handling the diff erent, sometimes conflicting, aims of traffic controllers. The proposed use of the concept of agents in this research is experimental.Assumptions and considerations on agent based urban traffic controlThere are three aspects where agent based traffic control and -management can im prove current state of the art UTC systems:- Adaptability. Intelligent agents are able to adapt its behaviour and can learn from e arlier situations.- Communication. Communication makes it possible for agents to co-operate and tune signal plans.- Pro-active behaviour. Due to the pro active behaviour traffic control systems are abl e to plan ahead.To be acceptable as replacement unit for current traffic control units, the system sho uld perform the same or better than current systems. The agent based UTC will require o n-line and pro-active reaction on changing traffic patterns. An agent based UTC should b e demand responsive as well as adaptive during all stages and times. New methods for tr affic control and traffic prediction should be developed as current ones do not suffice and cannot be used in agent technology. The adaptability can also be divided in several differ ent time scales where the system may need to handle in a different way (Rogier, 1999): - gradual changes due to changing traffic volumes over a longer period of time, - abr upt changes due to changing traffic volumes over a longer period of time, - abrupt, temporal, changes due to changing traffic volumes over a short period of ti me,- abrupt, temporal, changes due to prioritised traffic over a short period of timeOne way of handling the balance between performance and complexity is the use of a hierarchical system layout. We propose a hierarchy of agents where every agent is res ponsible for its own optimal solution, but may not only be influenced by adjoining agents but also via higher level agents. These agents have the task of solving conflicts between l ower level agents that they can't solve. This represents current traffic control implementat ions and idea's. One final aspect to be mentioned is the robustness of agent based syste ms (if all communication fails the agent runs on, if the agent fails a fixed program can beexecuted.To be able to keep our first urban traffic control model as simple as possible we have made the following assumptions: we limit ourselves to inner city traffic control (road seg ments, intersections, corridors), we handle only controlled intersections with detectors (int ensity and speed) at all road segments, we only handle cars and we use simple rule base s for knowledge representation.Types of agents in urban intersection controlAs we divide the system in several, recognisable, parts we define the following 4 typ es of agents:- Roads are represented by special road segment agents (RSA), - Controlled intersections are represented by intersection agents (ITSA), - For specifi c, defined, areas there is an area agent (higher level),- For specific routes there can be route agents, that spans several adjoining road se gments (higher level).We have not chosen for one agent per signal. This may result in a more simple soluti on but available traffic control programs do not fit in that kind of agent. We deliberately ch oose a more complex agent to be able to use standard traffic control design algorithms a nd programs. The idea still is the optimisation on a local level (intersection), but with local and global control. Therefor we use area agents and route agents. All communication ta kes place between neighbouring agents and upper and lower level ones.Design of our agent based systemThe essence of a, demand responsive and pro-active agent based UTC consists of s everal ITSA's (InTerSection Agent).,some authority agents (area and route agents) and o。

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MYOTRAC INFINITIDual SEMGThe Manufacturer: Thought Technology Ltd.2180 Belgrave AvenueMontreal, Quebec, CanadaH4A 2L8Product Name: MyoTrac Infiniti System Product #: T9800Device Name: MyoTrac Infiniti Encoder Device #: SA9800•Type BF Equipment •Internally powered equipment•Continuous operation•Read Instruction Manual•The pins of the connectors identified with the ESD warning symbol should not be touched unless ESB precautionary procedures are used.CAUTION•US Federal Law restricts this device to sale by, or on order of, a physician or any otherpractitioner licensed by the law of the state in which he or she practices to use or order theuse of this device.WARNING•Do not operate Active Sensors within 10 feet of an operating cellular phone, similar radio transmitting device, other powerful radio interference producing sources such as arcwelders, radio thermal treatment equipment, x-ray machines, or any other equipment thatproduces electrical sparks. Portable and mobile RF communication equipment can affectthis equipment.•With the MyoTrac Infiniti Encoder SA9800 use only with supplied power supply. GlobTek Part Number WR92B2500LF9P-Y-MED (WR95/WR93/WR97) or GS889•The PC used with MyoTrac Infiniti must be placed outside the patient/client environment(more than 3 meters or 10 feet) or the PC must comply with EN60601-1 (system safety).•After use, the Batteries or the Battery pack must be disposed of in accordance with local, state and federal regulations and laws.•After use, the Disposable Electrodes may be a biohazard. Handle, and when applicable, dispose of these materials in accordance with accepted medical practice and any applicablelocal, state and federal laws and regulations.•Reusable electrodes present a potential risk of cross-infection especially when used onabraded skin, unless they are restricted to a single patient or sterilized between patients. Ifsterilizing electrodes, employ only gas sterilization.•Radiated radio frequency electromagnetic fields can cause performance degradation in the MyoScan-Pro EMG sensor. In the worst case, an RF field strength of 22mV/M can causean increase of 1μV in the signal reading from a MyoScan-Pro sensor. Be sure to keep inmind that a very relaxed muscle should provide an EMG reading of approximately 1-3μV.•This device is capable of generating current densities exceeding 2mA r.m.s./cm² this may require special attention of the operator.•Avoid accidental contact between connected but unused applied parts and other conductive parts including those connected to protective earth.•Explosion Hazard; Do not use in the presence of a flammable anesthetic mixture with air, or with Oxygen or Nitrous Oxide.•Not to be immersed in water.•Take care in arranging patient and sensor cables to avoid risk of patient entanglement or strangulation.•The operator is responsible for ensuring the safety of any devices controlled or triggered by Infiniti equipment or software, or by any software or hardware receiving data from Infinitiequipment. Infiniti equipment must not be configured or connected in such a way thatfailure in its data acquisition, processing or control functions can trigger patient feedbackstimulus that poses an unacceptable level of risk.•Use of any equipment in a biofeedback or stimulation context should be immediatelyterminated upon any sign of treatment-related distress or discomfort.•Not to be connected to a patient undergoing MRI, Electro surgery or defibrillation.•Not for use with patients with undiagnosed pain conditions.•Only use the unit for which it was prescribed.•Do not immerse the unit in water or any other liquid substance.•Do not use if you have symptoms of bladder infection.•Do not use with diminished mental capacity or physical competence limiting the use of the device.•Caution should be used for patients with suspected or diagnosed heart problems.•Caution should be used for patients with suspected or diagnosed epilepsy.•Electrode placement and stimulation settings should be based on the guidance of theprescribing practitioner.•If damage is evident of the unit or accessories, discontinue use and contact your supplierfor further information on repair.•The system should not be used adjacent to or stacked with other equipment, if usedadjacent or stacked the unit should be observed to verify normal operation in theconfiguration in which it will be used.•Use of accessories, transducers or cables other than those specified by ThoughtTechnology ltd may result in increased emissions or decreased immunity of the equipmentto electromagnetic energy.ATTENTION•Sensors and equipment damaged by static electricity are not covered under warranty. Toprevent static discharge from damaging the sensor and/or encoders, use anti-static mats orsprays in your working area. A humidifier may also be used to prevent static environmentsby conditioning hot, dry air. It is recommended that all staff involved with the unit receive anexplanation of the ESD symbol and the precautions described above as a minimum.•Do not apply any electrode gel or equivalent directly on the sensor snaps. Always useelectrodes as a medium between the sensor and the client.•Not for diagnostic purposes, not defibrillator proof, not for critical patient monitoring.•To prevent voiding warranty by breaking connector pins, carefully align white guiding dot onsensor plug with slot on sensor input.•Make sure to remove electrodes from sensor snaps immediately after use.•Do not plug third party sensors directly into instrument inputs. Plug only ThoughtTechnology Active Sensor cable connectors into instrument inputs. All electrodes and thirdparty sensors must be connected to active sensors, either directly or through an adapter.•Remove batteries when the device is not being used for an extended period of time. Pleasedispose of battery following local regulations.INTENDED PURPOSE•Biofeedback, Relaxation & Muscle Re-Education purposes•Relaxation of muscle spasms•Prevention or retardation of disuse atrophy•Increasing local blood circulation•Muscle re-education•Maintaining or increasing range of motionNOTE•No preventative inspections required; maintenance must be performed by qualified personnel.Factory re-calibration can be requested.•The supplier will make available, upon request, circuit diagrams, component parts lists anddescription or other information required for the repair of product by qualified personnel.•The operator must be familiar with typical characteristics of signals acquired by thisequipment, and be able to detect anomalies in the acquired signal that could interfere withtreatment effectiveness. Depending on the importance of signal integrity, it may be advisableto continuously monitor the raw signals, in time and/or frequency domain, while the device isbeing used for biofeedback or other purposes. If anomalies are observed on acquired signals,and if you suspect a problem with electromagnetic interference, contact Thought Technologyfor a technical note on identification and remediation.•This product conforms to standards EN60601-1, EN60601-2-10 and EN60601-2-40; someencoder labeling may indicate superceded standards.MAINTENANCE AND CALIBRATION•Wipe encoder with a clean cloth•Factory testing and calibration ensure equipment accuracy and frequency response. Contact Thought Technology for factory re-calibration if necessary.STORAGE•Store in its original case at up to 90% humidity / 30C°TRANSPORTATION•Transport in its original caseManual # SA9814 Rev 4Guidance and manufacturer’s declaration – electromagnetic immunity The MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment, and that precautions regarding that environment are heeded.Immunity test IEC 60601test level Compliance level Electromagnetic environment –guidanceElectrostatic discharge (ESD) IEC 61000-4-2 ±6 kV contact±8 kV air±6 kV contact±8 kV airFloors should be wood, concrete orceramic tile. If floors are covered withsynthetic material, the relative humidityshould be at least 30 %.Electrical fast transient/burst IEC 61000-4-4 ±2 kV for powersupply lines±1 kV for input/outputlines±2 kV for powersupply lines±1 kV for input/outputlinesMains power quality should be that of atypical commercial or hospitalenvironment.SurgeIEC 61000-4-5 ±1 kV differentialmode±2 kV common mode±1 kV differentialmode±2 kV common modeMains power quality should be that of atypical commercial or hospitalenvironment.Voltage dips, short interruptions and voltage variations on power supply input linesIEC 61000-4-11 <5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 sec<5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 secMains power quality should be that of atypical commercial or hospitalenvironment. If the user of theMyoTrac Infiniti requirescontinued operation during powermains interruptions, it is recommendedthat the MyoTrac Infiniti bepowered from an uninterruptible powersupply or a battery.Power frequency (50/60 Hz) magnetic field IEC 61000-4-8 3 A/m 3 A/m Power frequency magnetic fieldsshould be at levels characteristic of atypical location in a typical commercialor hospital environment.NOTE U T is the a.c. mains voltage prior to application of the test level.NOTE 1 At 80 MHz and 800 MHz, the higher frequency range applies.NOTE 2 These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption Field strengths from fixed transmitters, such as base stations for radio (cellular/cordless) telephones and land mobile radios, amateur radio, AM and FM radio broadcast and TV broadcast cannot be predicted theoretically with accuracy. To assess the electromagnetic environment due to fixed RF transmitters, an electromagnetic site survey should be considered. If the measured field strength in the location in which the MyoTrac Infiniti is used exceeds the applicable RF compliance level above, the MyoTrac Infiniti should be observed to verify normal operation. If abnormal performance is observed, additional measures may be necessary, such as reorienting or relocating the MyoTrac Infiniti.Over the frequency range 150 kHz to 80 MHz, field strengths should be less than [V1] V/m.Guidance and manufacturer’s declaration – electromagnetic emissionsThe MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment.Emissions test Compliance Electromagnetic environment – guidanceRF emissions CISPR 11 Group 1 The MyoTrac Infiniti uses RF energy only for its internal function.Therefore, its RF emissions are very low and are not likely tocause any interference in nearby electronic equipment.RF emissionsCISPR 11Class BHarmonic emissionsIEC 61000-3-2Not applicableVoltage fluctuations/ flicker emissions IEC 61000-3-3 Not applicableThe MyoTrac Infiniti is suitable for use in all establishments,including domestic establishments and those directly connected tothe public low-voltage power supply network that suppliesbuildings used for domestic purposes.Table of ContentsAbout This Guide (9)Chapter 1 (10)Introduction to your MYOTRAC INFINITI™ Dual SEMG Encoder (10)System Requirements (11)MyoTrac Infiniti Components (12)Connection to the Client (15)Connection to the PC (19)Screen Elements (20)Thought Support (20)Settings Menu (21)Chapter 2 (25)SEMG sessions on your MYOTRAC INFINITI™ Dual SEMG Encoder (25)Open SEMG Sessions (25)Script SEMG Sessions (27)Chapter 3 (28)Data Management on your MYOTRAC INFINITI™ Dual SEMG Encoder (28)MyoTrac Infiniti Review (29)Chapter 4 (30)Display Options on your MYOTRAC INFINITI™ Dual SEMG Encoder (30)Displays (30)Chapter 5 (34)Flow on your MYOTRAC INFINITI™ Dual SEMG Encoder (34)Chapter 6 (35)Reference (35)Technical Support and Order Placing (36)Technical Support (36)Product Numbers & Accessories (37)Placing Orders (38)Specifications (39)MyoTrac Infiniti Hardware Copyright Notice (44)About This Guide Welcome to the MYOTRAC INFINITI™ encoder. This guide is designed to help you get up and running quickly with your new encoder. It will describe the operation of the encoder, and how it interfaces to the host personal computer (PC).It walks you through:•Physical Operation of the encoder.• EMG sessions.• Data management.• Display options.After you have become familiar with the key concepts of your new encoder, you can use the rest of this guide as a reference for less common tasks, and also as a source of information if you have problems operating it.Chapter 1 Introduction to your MYOTRAC INFINITI™ Dual SEMG EncoderThis chapter explains the physical interface with the MyoTrac Infiniti Encoder, how to use it for the first time, and how to transfer data to the host PC.Getting to know your MyoTrac Infiniti Dual SEMG EncoderWhat is a MyoTrac Infiniti Dual SEMG Encoder?The MyoTrac Infiniti is the cutting edge in handheld, dual channel Surface Electromyography(SEMG). With it you will be able to deliver targeted and customized treatment directly to the client’s clinically relevant areas.A simple first approach has been adopted in the design of the MyoTrac Infiniti to make it as easyand fast as possible to get the clinical results desired from this powerful device.Customizing the MyoTrac Infiniti to your clinical needs couldn’t be easier; all users input is directed through a series of intuitive and guided screens using touch screen technology.The partnership of the MyoTrac Infiniti with the BioGraph Infiniti PC software enhances yet further the power and flexibility of the MyoTrac Infiniti. This link enables you to transfer session data to the PC for further viewing, analysis and reporting, in real time or post session.System RequirementsTo install the BioGraph Infiniti software, your computer system must meet or exceed the following requirements.•IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P4 speed 3GHz or higher), Desktop or Laptop withtwo monitor capability•Windows 2000/XP Professional or Home edition.•50 - 60 gigabytes hard disk space for video recording and processing. (Thesoftware needs 2.5 gigabytes to installand run on available hard drive space) •Memory, 512 MB of RAM or more•CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor•32 bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on thedesired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •MS Word 97 or higher (for printingpurposes)•Compact Flash Reader (For use with compact flash card only)•Webcam 30 frames per second (for video purposes only)NOTE: When using certain more complex screens, you must adhere to the Recommended Computer Requirements.••IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P3speed 1.8 GHz), Desktop or Laptop •Windows 2000/XP Professional or Home edition.•10 - 20 gigabytes hard disk space •(The software needs 2.5 gigabytes to install and run on available hard drivespace)•Memory, 256 MB of RAM or more •CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor •16 Bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on the desired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •Word 97 or higher (for printingpurposes)NOTE: For most recent computer requirements contact Thought Technology Ltd for MAR473Update informationPeriodically updates may become available for the BioGraph Infiniti software and for the MyoTrac Infiniti Hardware. Please contact your local distributor or visit our website for further information on how to obtain updates.MyoTrac Infiniti Components•Compact Flash for increased memory capacity and one method for transfer of data to the PC.•USB for real time transfer of data to the PC.•Touch screen enables graphically guided navigation through the software.•Rugged Ergonomic Case, easy to hold or attach to the subject and will withstand the rigors of daily use.•Battery Charging jack for wall connection enables fast built-in battery charging.•Headphone Jack for stereo sound feedback (or use the built-in speaker).•Push button On/Off switch to prevent accidental switching.• 2 Channels of Surface EMG.PowerThere are three basic methods to power the MyoTrac Infiniti unit: Inserting batteries into the battery compartment of the unit, plugging it into the wall using the supplied AC adapter, or plugging it into a powered up computer using a USB cable.The MyoTrac Infiniti is available with battery charging capabilities. It will work with four standard Alkaline AAA batteries available in all consumer electrical stores. It is also possible to run the unit on removable, externally rechargeable batteries. A rechargeable battery pack is supplied with the MyoTrac Infiniti and can be charged while still inside the unit.Note: When changing batteries it is recommended to plug the unit into external power, either USB or wall transformer so that data is not lost. Failure to supply external power will result in data and script loss.The battery compartment cover slides open by pushing up using the notch provided. Place four AAA batteries in the slots, observing the polarity as illustrated. Please note that a diagram of the correct battery polarity is embossed on the inside surface of the compartment.Alternatively it is possible to use a rechargeable battery pack (Thought Technology Part Number MI1028). This battery pack is plugged into the connector in the battery compartment marked BATT. The pack then fits into the normal battery area. Note: only use battery packs from Thought Technology or authorized representative, as use of other battery packs will damage the device.A wall mounted AC power adapter, supplied with the MyoTrac Infiniti, is used to connect the unit toan electrical outlet. This can be used in conjunction with the batteries or without.The unit can also be powered from the computer via the USB cable. The cable is connected to the unit on one side and on the other side to the USB port of the computer. This can be used inconjunction with the batteries or without.Charging the BatteriesNote: exact power supply subject to change without notice.Internal ChargerIf your MyoTrac Infiniti was supplied with a wall mounted AC adapter it is possible to charge the battery pack while it is inserted in the device.Note: Only use Thought Technology Ltd supplied wall mounted chargers with this device. Failure to do so could result in potential injury. Use only GlobTek Part Number WR9אB2500LCP-Y-MED where א= 2 for North America, א=3 for Europe, א=5 for United Kingdom and א=7 for Australia with the exception of Japan where the part number is GS 889.To start the charging plug in either the wall mounted AC adaptor or the USB cable. A full charging cycle from fully empty to fully charged will take approximately 2hrs for AC adaptor and 5.5hrs for the USB cable. The unit can be used while plugged in to either power source. The charging cycle does not need to be completed in full; it can be stopped at anytime by removing the connector.When the unit is turned off while plugged into an external power source, the screen displays a battery symbol. Charging action is shown with an animation of the battery filling up. When the battery is fully charged, the symbol shows a full battery.If the unit is plugged into an external power source while it is turned off, it will start charging within one minute.The state of the battery charging is available by going to the power menu in the settings menu of the device. It indicates the current mode of power and whether the unit is currently charging the batteries.Note: The rechargeable batteries must be fully charged prior to initial use. In order for the batteries to reach full capacity it may be necessary to charge them several times (~2-8) after initial use.MemoryRecorded data can be saved using three methods - choose the one which most closely matches your usage needs. To select saving method, select the Settings menu from the main menu, and tap on the Save icon.•Internal Memory – Limited size, only the statistical summaries are recorded. Specifically, the statistics for 13 open sessions or 9 training sessions (work/rest) or 6 assessment sessions(work/rest + fast-flick + endurance) can be recorded. Data can be lost if the batteries areremoved from the unit for longer than a few minutes.•Compact Flash Card – Most flexible method of data saving: save all the raw data for review on the encoder or for download to the PC. Available in most electronics stores in a range ofmemory sizes. Since all EMG data is recorded, the amount of data that is saved to thecompact flash card depends on the size of the card:hours64MB 1.75128MB 3.5 hours256MB 7 hours512MB 14 hourshours1GB 27.5hours2GB 55.5The encoder is delivered with a protective insert in the compact flash slot. To remove it, push the button next to the slot once to eject the card. The CF card can then be inserted; you willnotice that the CF card can only be inserted one way into the encoder to protect from incorrect insertion. When inserted properly it will be flush with the encoder rear. Follow the procedure above to remove this card when no longer required, and re-insert the protective insert. CFcards require a CF card reader to transfer data to the PC. The CF cards and reader can bepurchased from most computer stores. Before its first use in the encoder, a CF card requires PC formatting using the file manager, then format the card using the BioGraph Infiniti MainApplication. Formatting and transferring CF data to the PC is covered in depth in theBioGraph Infiniti software manual.•Real Time PC Transfer – Connect to the PC via the USB and save and display the data on the PC in real time. See the following section “Connection to the PC”.Attention: Do not remove the CF card without first stopping recording. If the CF card is removed during recording, you will lose all the data for the current session.TappingLike using a mouse on a computer screen the MyoTrac Infiniti allows you to use your finger or a stylus to tap the buttons directly on the screen. The first time you start your handheld unit, or if the power has been disconnected for a while, you will be guided through a set of welcome screens including calibration, time and date setting. The calibration aligns the internal circuitry of theencoder with its touch sensitive screen so that when you tap a button on the screen, the handheld unit can detect exactly which button is being pressed. It is recommended to use a stylus when calibrating the device as it will provide a more accurate calibration than using a finger.Note:Always use a finger or stylus for tapping the screen. Never use a pen, pencil or othermarking or sharp object on the screen.Damage resulting from misuse of the screen is notcovered by the warranty.The software is designed so that once the screen has been calibrated it is possible to use all the buttons with a finger. In many cases the touch sensitive area is greater than the graphicalconstraints of the button allowing for easier operation using a finger. As necessary wipe screen with a dry cloth to clean. Screen protectors are available from good stationary suppliers and are a good way to extending the life of your screen.Connection to the ClientDepending on the type of session you are going to record there are different ways to connect the two channels to the client. Either plug the extender cable into the device directly and connect to the client with EMG electrodes, or plug them into the pre-amplifier and the pre-amplifier into the MyoTrac Infiniti.Attention: When you insert the extender cable (lead wire) into the electrode connector, MAKE SURE THAT NO BARE METAL OF THE PINS IS EXPOSED.Before applying electrodes, be sure the skin surface is cleaned and dried. Make sure theelectrodes are placed firmly to the skin and make good contact between the skin and electrodes.Please consult the clinical guide for information on electrode selection for different placements. The illustration below shows the division of the body into six areas of treatment.Arms and ShouldersHead and NeckAbdominalsBack and ButtocksLegs and HipsWhen connecting a sensor or extender cables, be sure to properly line up the guiding dot on the top of the plug with the notch in the encoder's input socket. Forcing the plug into the jack in any other position may damage your equipment.Using the MyoTrac Infiniti with AC Power Adapter or Connected to a PCThe MyoTrac Infiniti is designed for safe operation on ungrounded AC power sources. However, if you are using the MyoTrac Infiniti while it is connected to an ungrounded AC power source, for best results you may need to follow some simple guidelines for skin preparation and electrode placement. These measures will help to avoid falsely elevated EMG readings while the muscle is at rest.If you notice elevated resting EMG levels not related to the patient’s condition, and if this occurs only when the unit is connected to AC power (directly via the supplied AC adapter or indirectly via a USB connection to the PC), and if it is necessary to run the MyoTrac Infiniti on ungrounded power(i.e. no 3rd ground pin on the AC wall socket or on the PC power supply), try the followingtechniques to improve the readings.First, if you are using a PC with only 2 prongs on the wall plug and you have a grounded outlet (3 pin wall sockets with a working ground), plug the ac adapter into the MyoTrac-Infiniti and into the grounded outlet to provide a ground for the system.If you have no opportunity to ground either the PC or the AC adapter, use the following electrode placement tips:•If the EMG site is located on an extremity or limb, be sure to place the REF (black colored) electrode more proximally (on or closer to the trunk of the body) than the sense electrodes(yellow and blue), and at least ten centimeters away from either sense electrode.•Prepare the skin under all three electrodes, using a product designed for skin preparation prior to electrode application (mild abrasives such as NuPrep are effective).•If you are using Ag/AgCl (silver/silver chloride) electrodes, put some conductive electrode paste or cream on them before applying them to the skin, or try using gel-type rather than dry Ag/AgCl electrodes.Resting EMG readings will not be affected by connection to AC power, in the following cases:•Running the MyoTrac Infiniti stand-alone, with no AC power adapter and no connection to the PC (only on its rechargeable batteries).。

英文-无机纳米材料光解水ppt课件

Contents
1
Introduction
2
Brief history
3 Inorganic nanostructures
4 Conclusion and outlook
carbon free energy technology
The solar energy received on the Earth’s surface meets current and future human energy demand.
photoelectrochemical water splitting
Exploit scaling laws and specific effects at 3 the nanoscale to enhance the efficiency of
existing semiconductors and metal oxides
three main strategies
Coat conventional photovoltaic cells with 1 cocatalysts for water splitting or with
protecting layers to inhibit photocorrosion
Development of new metal oxide materials 2 that combine suitable properties for
Advantages
✓ Shortened carrier collection pathways ✓ Improved light distribution ✓ Quantum size confinement ✓ Potential determining ions (PDI) ✓ Surface area-enhanced charge transfer ✓ Multiple exciton generation

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Abstract — Mono- and multifilamentary MgB 2/Fe tapes and wires with high transport critical current densities have been prepared using the powder-in-tube (PIT) process. The fabrication details are described. The effect of powder grain sizes and recrystallization temperature on j c has been investigated. At 25K and 1 T, j c values close to 105 A/cm 2 were measured, while j c of 106 A/cm 2 were extrapolated for 4.2K/0T in our monofilamentary tape. MgB 2/Fe tapes exhibit high exponential n factors for the resistive transition: n ≈ 80 and 40were found at 5 T and 7 T, respectively. The highest transport j c values obtained so far in MgB 2/Fe wires with 7 filaments were 1.1 × 105 A/cm 2 at 4.2 K and in a field of 2 T, which is still lower than for monofilamentary tapes. The function ()qpb bFp −⋅∝1has been established over thewhole field range, and exhibits a maximum at18.0≅p F .Improved deformation and recovering processing is expected to lead to higher j c values.Index Terms — Mono- and multifilamentary MgB 2superconducting tapes and wires; transport critical current densities; Fine MgB 2 powder; n factors; Pinning forceI. I NTRODUCTIONhe recently discovered superconductor MgB 2 with T c = 39K [1] is characterised by weak link free grain boundaries [2] and low material cost, and is thus promising for potential application at 25 K. The feasibility of MgB 2 wires or tapes with high critical current density using the Powder-In-Tube (PIT) method has been demonstrated, either with [3]- [10]or without [11], [12] recrystallization after deformation. The j c values of these tapes at 4.2 K, 0 T are in the range of ~ 105-106 A/cm 2. We have previously reported [3], [4] on the fabrication of highly dense monofilamentary MgB 2 tapes with large j c values using Ni and Fe as sheath materials [3], [4], [6].Manuscript received August 5, 2002. This work was supported by the Fond National Suisse de la Recherche ScientifiqueHongli Suo, P. Lezza, D. Uglietti, V. Abächerli and R. Flükiger are with Département de Physique de la Matière Condensée, Université de Genève, 24 Quai Ernest-Ansermet, Genève 4, CH-1211, Switzerland (telephone: +41-22-7026578, e-mail: Hongli.Suo @physics.unige.ch).C. Beneduce is with Bruker Biospin, Magnetics Division,Industriestrasse 26, Ch-8117 Fällanden, Switzerland.In this work, we restrict our study on Fe as a sheath materialand investigate more deeply the effect of the grain size of the starting powder and the annealing temperature on the properties of MgB 2 tapes. We found a significant enhancement of the n factors in our monofilamentary tapes using finer starting powder. The results on MgB 2/Fe multifilamentary wires and tapes are also presented.II. E XPERIMENTALThe fabrication of the MgB 2/Fe tapes was previously described [3], [4], [13]. In the present work, we analyzed the effect of various powder grain sizes obtained by ball milling for 2, 3, 14 and 100 hours, respectively. After drawing to 2 mm diameter, the wires were cold-rolled to tapes. Annealing was performed between 920°C and 980°C for 0.5h in Ar atmosphere.III. R ESULTSA. j c Values in Monofilamentary MgB 2/Fe Tapes 1) Thickness and j c in As-rolled and Annealed TapesFig. 1. Field dependence of the transport j c values at T = 4.2 K in both as-rolled and annealed MgB 2/Fe tapes with different thicknesses.We fabricated the tapes with thicknesses of 380 and 230 µm,corresponding to a filling factor of 28% and 25%, respectively.The field dependence of j c in these MgB 2/Fe tapes, both beforeTransport critical current densities and n factors in mono- and multifilamentary MgB 2/Fe tapesand wires using fine powdersH.L. Suo, P. Lezza, D. Uglietti, C. Beneduce, V. Abächerli and R. FlükigerT01234567891011121314101010101010J c (A /c m 2)µ0H (Tesla)and after the annealing, is shown in Fig. 1. A comparison at 2 T shows that the thinner as-rolled MgB2/Fe tape (230 µm) yields higher current densities, reaching 2 × 104 A/cm2 at 4.2 K (unannealed). This result indicates that the tape with lower filling factor corresponds to a higher j c value, this confirming the observation of Grasso [11] and showing that the filling factor is an important parameter.The final recrystallization anneal caused a densification, then leading to a strong enhancement of j c to 8×104 A/cm2 in a field of 3.5 T for 230 µm thick Fe/MgB2 tape and 104 A/cm2 in a field of 6.5 T for the 380 µm thick Fe/MgB2 tape. After recrystallization, similar j c vales were obtained for both thicknesses, thus suggesting that the final density inside the filament is quite similar.Quenching occurred in all our samples above a givencurrent, which was higher in 230 µm thick MgB2/Fe tape than in the 380 µm MgB2/Fe one. This difference is thought to be due to the smaller core thickness of the thinner MgB2/Fe tape (70µm compared to 160 µm for the 380 µm thick MgB2/Fe tape). Further reduction of the filament thickness is expected to improve the thermal stability of MgB2/Fe tapes and wires.2) Effect of Grain Size of Starting Powder on j cWe have previously reported [13] that after reducing the MgB2 grains to a micrometer size by ball milling, both the critical current density, j c and the irreversibility field, µ0H irr were enhanced, while the upper critical field, µ0H c2, remained unchanged. In the present work we performed ball milling in an agate mortar containing agate balls for times t = 2-100 h. The various powder sizes in Fig. 2 are represented by the peak values in the size distribution as obtained by granulometry: (a) after 2 hours the two observed peaks at 3 and 30 µm, respectively, are characterised by 3/30 µm, and similarly, (b) 3 hours: 1.5/10 µm, (c) 14 hours: 1/7 µm and (d) 100 hours: 1 µm. Fig. 2.Distributions of powder grain sizes: (a) 2 h: powder 3/30 µm; (b) 3 h: powder 1.5/10 µm; (c) 14 h : powder 1/7 µm; (d) 100 h: powder 1µmWe prepared Fe/MgB2 tapes using the powders (a) to (d) by the same deformation processing and heat treatment. Fig. 3compares the j c values in these tapes annealed at 950°C. For comparison, the j c(H) curves of an annealed MgB2/Fe tape produced directly using as-purchased powder with a wide size distribution centred at around 60 µm are also shown in the same figure. For the initially coarse-grained powder, the j c is markedly lower than that of ball milled tapes. In the tape with powder (a) 3/30 µm, we obtained the highest j c value of 104 A/cm2 at 4.2 K and in a field of 6.5 T. Extrapolating the field dependence of j c in this tape yielded self-field values close to 1 MA/cm2. At T = 25 and 30 K, j c values well above 104 A/cm2 were obtained at fields of 2.25 and 1.0 T, respectively. With the reduction of the grain size of starting powder, the j c values slowly decreased, the lowest j c values being observed in the tape based on powder (d) 1 µm. In principle, it was expected that finer powders would lead to higher j c values due to the enhanced interface between grains. The actual results suggest a possible influence of impurities at the powder surface, as a consequence of the grinding procedure. The powder with the smaller grain size have considerably larger total grain surface, which makes the grains more active thus absorbing more oxygen during high temperature annealing, therefore resulting in a degradation of the transport j c values.Fig. 3.Field dependence of the transport j c values at T = 4.2 K in annealed MgB2/Fe tapes prepared by different powders.3) Effect of Annealing Temperature on Transport j cWe studied the effect of annealing temperatures between 920°C and 980°C on j c values in tapes prepared by powder (b) 1.5/10 µm. As shown in Fig. 4, a higher j c value is found when lowering the temperature from 980°C to 920°C. At 920°C, we obtained the same j c values in this tape as for the tape with by powder (a) 3/30 µm, annealed at 950°C. This result suggests that the optimum annealing temperature could differ for MgB2 tapes based on different powder grain sizes: for tapes produced by smaller grain size, a lower annealing temperature has proven to give better results (Fig. 4). Our experiments show a good reproducibility of the high j c values of tapes produced in different ways.101010101010µH (Tesla)J c(A/cm2)Fig. 4. Field dependence of the transport j c values at T = 4.2 K in MgB 2tapes annealed at different temperatures.4) Exponential n factors in Monofilamentary MgB 2/Fe TapesTo analyze the possibility of MgB 2 conductor to work in the persistent mode, we studied the exponential n factors of the tapes. The logarithmic E-J curves measured at 4.2 K can be reasonably well approximated by a local power-law, with the electric field criterion E c = 10-6 V/cm:()()nc c j j E E≈.Fig. 5. Field dependence of the exponential n factors in annealed MgB 2/Fe tapes.By fitting this relation to our data in the electric field range of 0.5 µV/cm < E < 5 µV/cm, we obtained n factors shown in Fig. 5 for the tape prepared by powder (a) 3/30 µm. The factor is determined to be ~ 30 at 6 T, and decreases exponentially to 10 at 8.5 T. By fitting our data in the range of 0.1 µV/cm < E < 1µV/cm, we obtained the factors for the tapes fabricated by powder (b) 1.5/10 µm, also shown in Fig. 5. A strong enhancement of n factors was observed: the n factors of the three tapes annealed at 980, 950, 920°C are similar, being ~ 80 at 5 T and also decreasing exponentially to ~ 40 at 7 T. This improvement of n factors may be related to the smaller grain sizes used for those tapes and thus to the correspondinghigher local homogeneity. The high n factors open the possibility to use MgB 2 magnets in the persistent mode for fields up to 7 T at 4.2 K and to 2.5 T at 25 K.B. Multifilamentary Wires and TapesWe have previously reported [14] the fabrication and superconducting properties of multifilamentary MgB 2/Fe wires.The highest j c values were obtained in MgB 2/Fe square wires (1.7 mm dimension) with 7 filaments produced by two-axial rolling, followed by annealing at 950°C. More recently, in order to decrease core thickness and improve thermal stability, we have developed a new configuration of multifilamentary tape with 9 filaments. The preparation consists of packaging thin MgB 2/Fe single tapes into rectangular Fe tube (Width: 9 mm,Thickness: 5 mm) and repeating the same deformation (two-axial rolling) procedure. Two recovery annealings at 600°C for 1hour were performed for softening the Fe sheath which showed considerably work hardening during rolling. The annealed wire was deformed again by two-axial rolling to final tape thickness of 0.9 mm. The multifilamentary tape has very uniform transversal sections, as can be seen from the SEM micro-graphs of polished cross-sectionsof this tape (Fig. 6).Fig. 6. Transversal cross-section of multifilamentary MgB 2/Fe tape with 9 filaments (thickness: 0.9 mm)Fig. 7. Transport critical current densities at T = 4.2 K as function of applied field in annealed MgB 2/Fe multifilamentary wires. For comparison, the transport j c curve of a monofilamentary MgB 2/Fe tape is also shownFig. 7 summarizes the j c values at 4.2 K as function of applied f ield for our multifilamentary MgB 2/Fe wires (1.7 mm dimension) and tapes (0.9 mm thickness). The j c value in the MgB 2/Fe square wire with 7 filaments was 1.1×105 A/cm 2 atµ0H (T)n f a c t o r10101010T r a n s p o r t J c (A /c m 2)µ0H (Tesla)101010101010µ0H (Tesla)J c (A /c m 2)4.2 K and 2 T. Quenching was also observed on the present multifilamentary wires, but the measurements could be extended to lower field values. The estimated self-field value of j c at 4.2 K in this square wire was close to 4×105 A/cm 2. The cross over of j c shown in Fig. 7 between the two multifilamentary configurations has not been fully understood and may be due to different states of densitiy and pared with the MgB 2/Fe monofilamentary tapes, the j c values in both multifilamentary conductors are substantial lower, which might be due to the poor connectivity of grains (confirmed by SEM), indicating a lower density. In addition,the effect of these intermediate anneals on the 9-filaments tape may have had a negative influence. The improvement of thermal stability, deformation processing as well as the optimization of intermediate anneals appear a challenge for the future development of multifilamentary MgB 2/Fe tapes.C. Pinning Force (in Monofilamentary Tapes)Fig. 8. Reduced pinning force at different temperatures for tape by powder 3/30 µm (open symbols). Close symbols refer to tapes by powder 1.5/10 µm. The dashed line is the Kramer law with exponents p=0.6 and q=3.2.From I c (B) it is possible to calculate the pinning force, which can be fitted with the usual relation()qp p b b F −⋅∝1where b is the ratio between B and B*, B* being the irreversibility field. Unfortunately the range for the available transport measurements is restricted to high fields (4 T - 7 T),due to insufficient thermal stability. As a consequence it is quite difficult to fit the data to find p and q and to locate the position of the peak. Based on our previous results [13], [15]on the whole field range showing that the values of inductive and resistive j c are the same, we have performed an analysis using the inductive j c reported by Suo et al. [4] to establish an universal scaling law for MgB 2 monofilamentary tapes. The inductive data at 10, 20, 30K have been used to determine the exponents of the Kramer law. The irreversibility field has been estimated using the j c = 102A/cm 2 criterion. The coefficients have been found to be p =0.6 and q =3.2 (quite different values respect to Nb 3Sn), and have been used to extrapolate the transport measurements to lower fields. Moreover B irr and F pmaxhave been calculated from the fit and the transport measurements have been plotted together with the inductive ones in the normalised plot shown in Fig. 8.IV. C ONCLUSIONIn conclusion, we reported on the preparation of mono- and multifilamentary MgB 2/Fe tapes and wires. We found that both the grain size of the starting powder and annealing temperature were determinant for getting higher j c values. The estimated self-field value of j c in annealed monofilamentary MgB 2/Fe tapes at 4.2 K was close to 106 A/cm 2. An enhanced n factor (e.g. ∼ 80 at 5 T) was found for monofilamentary tapes prepared by finer starting powders, which is attributed to a higher local homogeneity. This result confirms the possibility to use MgB 2tapes for persistent mode operation. Multifilamentary MgB 2/Fe wires and tapes have been prepared, showing lower j c values than the monofilamentary tapes. The estimated self-field values of j c at 4.2 K in these multifilamentary wires exceeded 4×105 A/cm 2. The function ()qp b b Fp−⋅≈1has beenestablished over the whole field range, and exhibits a maximumat 18.0≅p F . Improved deformation and recovering processing is expected to lead to higher j c values.R EFERENCES[1] D.C. Larbalestier, L. D. Cooley, M. O. Rikel, A. A. Polyanskii, J.Jiang, S. Patnaik, X. Y. Cai, D.M. Feldmann, A. Gurevich, A. A.Squitieri, M. T. Naus, C. B. Eom, E. E. Hellstrom, R. J. Cava, K. A.Regan, N. Rogado, M. A. Hayward, T. He, J. S. Slusky, P. Khalifah,K. Inumaru and M. Haas, Nature, 410, 186 (2001).[2] M. Dhallé, P. Toulemonde, C. Beneduce, N. Musolino, M. Decroux,and R. Flükiger, Physica C. 363, 155(2001).[3] H.L. Suo, C. Beneduce, M. Dhallé, N. Musolino, J .-Y. Genoud andR. Flükiger, Appl. Phys. Lett. 79, 3116 (2001).[4] H.L. Suo, C. Beneduce, M. Dhallé, N. Musolino, X.D. Su, E. Walkerand R.Flükiger, CEC/ICMC Conference, Madison, USA July (2001),“Advances in Cryogenic Engineering”, volume 48, P-872[5] B. A. Glowacki, M. Majoros, M. Vickers, J. E. Evetts, Y. Shi, and I.McDougall, Supercond. Sci. Technol. 14, 193 (2001).[6] S. Jin, H. Mavoori, C. Bower and R. B. van Dover, Nature 411, 563(2001).[7] S. Soltanian, X.L. Wang, I. Kusevic, E. Babic, A.H. Li, H.K. Liu,E.W. Collings and S.X. Dou, Physica C 361, 84-90 (2001).[8] R. Nast, S.I. Schlachter, S. Zimmer, H. Reiner, W. Goldacker,Physica C, in press.[9] W. Goldacker, S.I. Schlachter, S. Zimmer, H. Reiner, Supercond.Sci. Technol. 14, 787-793 (2002).[10] A. K. Pradhan, Y. Feng, Y. Zhao, and N. Koshizuka, Appl. Phys.Lett. 79, 1649 (2001).[11] G. Grasso, A. Malagoli, C. Ferdeghini, S. Roncallo, V. Braccini, M.R. Cimberle and A. S. Siri, Appl. Phys. Lett. 79, 230 (2001).[12] H. Kumakura, A. Matsumoto, H. Fujii and K. Togano, cond-mat/0106002, Appl. Phys. Lett. 79, 2435 (2001).[13] C. Beneduce, H.L. Suo, N. Musolino, and R. Flükiger, submitted toPhysica C (submitted for publication).[14] H.L. Suo, C. Beneduce, X.D. Su and R. Flükiger, Supercond. Sci.Technol 15 (2002) 1058-1062.[15] R. Flükiger, P. Lezza, C. Beneduce and H.L. Suo, InternationalWorkshop on Superconductivity in Magnesium Diboride and Related Materials, Genoa, Italy, June 17-19, 2002 (submitted for publication).0.00.20.40.60.81.0F p /F p M A XH/H irr。