Dynamic Simulations of the Kosterlitz-Thouless Phase Transition

合集下载

材料表界面作业答案

二维理想气体定律理想气体状态方程
πA=RT
表面压较小的情况下成立
pv=RT
忽略了分子间互相作用力，利用理想化模型推导公式低压、高温条件下成立
总结：界面化学四大ຫໍສະໝຸດ 律 Laplace 方程 Kelvin 公式
p (1/ r1 1/ r2 )
P 2 V 2 M P0 r r
求出表面张力σ，即：
(2)修正的原因：①把凹凸月面当作球面近似处理。②只有在凹月面的最低点毛细上升的高度才是h ，凸月面的最高下降才为h ，其余各点均大于h 。
6.试用Kelvin公式解释空气中水蒸汽过饱和的原因。在20℃下水的密度ρ =998.2kg/M3,表面张力为72.8*10（-3）N/m，若水滴半径为10（-6）cm，求水的过饱和度。答：（1）由Kelvin公式： P 2 V 2 M RT ln (2-40) P0 r r P0 为平液面的蒸汽压，P 为弯液面的蒸汽压，V 为液体摩尔体积，r 为弯液面的曲率半径。由上式可知，液滴的半径越小，其蒸气压越大。下面图示为根据 Kelvin 公式得出的正常液体（平面）与小液滴的饱和蒸气压曲线。
5. 毛细管法测定液体表面张力的原理是什么？为什么要对毛细管法进行修正？答：原理：液体在毛细管中易产生毛细现象。由Laplace方程推广到一般情况:
gh=2 /r (2-20) 其中△ρ 为气液两相密度之差, θ 为液体与管壁之间的接触角
，r为毛细管的半径，由上式，从毛细管上升或下降高度h可以
v a3 a v1/ 3 0.00951/ 3
其表面积为： A=6a =6*0.0095 =
2 2/3
比表面积=
表面积 6*0.00952/3 = （cm 2/g) 质量 0.1

nature

本科生科研训练题目高能量密度柔性赝电容器中的二维磷酸氧钒超薄结构（翻译）院系物理科学与技术学院专业物理学基地班年级2012级学生姓名李赫学号**********二0一三年十二月二十日natureCOMMUNICATIONS2013年2月5号收到稿件2013年8月12日接受稿件2013年9月12日发表稿件DOI: 10.1038/ncomms3431高能量密度柔性赝电容器中的二维磷酸氧钒超薄结构二维材料一直以来在柔性薄膜型超级电容器，以及表现有关灵活性，超薄度甚至透明度的强劲优势上都是一个理想的构建平台。

要探索新的具有高电化学活性的二维赝电容材料，我们需要获得具有高能量密度的柔性薄膜超级电容器。

这里我们介绍一个无机石墨烯类似物，a1钒，一种少于6个电子层的磷酸盐超薄纳米片来作为一个有发展前景的材料去构建柔性全固态超薄赝电容器。

这种材料展示了一个在水溶液中氧化还原电位(~1.0V)接近纯水电化学窗口电压（1.23V）的赝电容柔性平面超级电容器。

通过层层组装构建出的柔性薄膜型超级电容器的氧化还原电位高达1.0V，比容量高达8360.5 μF∙cm-2，能量密度达1.7 mWh ∙cm-2，功率密度达5.2 mW∙cm-2。

现在，便携式消费电子产品的需求在快速增长，如柔性显示器，手机和笔记本电脑，极大推动了在全固态下的柔性能源设备的开发。

作为未来一代的储能装置，柔性薄膜型超级电容器在全固态下提供柔韧性，超薄型和透明度的协同效益。

在不同的类型的超级电容器中，与电双层电容器相比，赝电容器因为自身的高活性表面的电极材料可以快速发生的氧化还原反应而具有明显优势。

与锂离子电池相比，它表现出更高的能量密度，以及更高的功率密度。

因此，承载着为实现高性能的柔性薄膜型超级电容器的全固态伟大的承诺（FUSA）与电容行为。

具有赝电容特性的二维（2D）类石墨烯材料代表着一个有前途的方向可以去实现全固态下的高能量密度柔性超级电容器，和潜在的优良的机械柔性。

PbI2

Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a)Duyen H. Cao, Constantinos C. Stoumpos, Christos D. Malliakas, Michael J. Katz, Omar K. Farha, Joseph T. Hupp, and Mercouri G. KanatzidisCitation: APL Materials 2, 091101 (2014); doi: 10.1063/1.4895038View online: /10.1063/1.4895038View Table of Contents: /content/aip/journal/aplmater/2/9?ver=pdfcovPublished by the AIP PublishingArticles you may be interested inParameters influencing the deposition of methylammonium lead halide iodide in hole conductor free perovskite-based solar cellsAPL Mat. 2, 081502 (2014); 10.1063/1.4885548Air stability of TiO2/PbS colloidal nanoparticle solar cells and its impact on power efficiencyAppl. Phys. Lett. 99, 063512 (2011); 10.1063/1.3617469High efficiency mesoporous titanium oxide PbS quantum dot solar cells at low temperatureAppl. Phys. Lett. 97, 043106 (2010); 10.1063/1.3459146Near-IR activity of hybrid solar cells: Enhancement of efficiency by dissociating excitons generated in PbS nanoparticlesAppl. Phys. Lett. 96, 073505 (2010); 10.1063/1.3292183Effects of molecular interface modification in hybrid organic-inorganic photovoltaic cellsJ. Appl. Phys. 101, 114503 (2007); 10.1063/1.2737977APL MATERIALS2,091101(2014)Remnant PbI2,an unforeseen necessity in high-efﬁciency hybrid perovskite-based solar cells?aDuyen H.Cao,1Constantinos C.Stoumpos,1Christos D.Malliakas,1Michael J.Katz,1Omar K.Farha,1,2Joseph T.Hupp,1,band Mercouri G.Kanatzidis1,b1Department of Chemistry,and Argonne-Northwestern Solar Energy Research(ANSER)Center,Northwestern University,2145Sheridan Road,Evanston,Illinois60208,USA2Department of Chemistry,Faculty of Science,King Abdulaziz University,Jeddah,Saudi Arabia(Received2May2014;accepted26August2014;published online18September2014)Perovskite-containing solar cells were fabricated in a two-step procedure in whichPbI2is deposited via spin-coating and subsequently converted to the CH3NH3PbI3perovskite by dipping in a solution of CH3NH3I.By varying the dipping time from5s to2h,we observe that the device performance shows an unexpectedly remark-able trend.At dipping times below15min the current density and voltage of thedevice are enhanced from10.1mA/cm2and933mV(5s)to15.1mA/cm2and1036mV(15min).However,upon further conversion,the current density decreases to9.7mA/cm2and846mV after2h.Based on X-ray diffraction data,we determinedthat remnant PbI2is always present in these devices.Work function and dark currentmeasurements showed that the remnant PbI2has a beneﬁcial effect and acts as ablocking layer between the TiO2semiconductor and the perovskite itself reducingthe probability of back electron transfer(charge recombination).Furthermore,weﬁnd that increased dipping time leads to an increase in the size of perovskite crys-tals at the perovskite-hole-transporting material interface.Overall,approximately15min dipping time(∼2%unconverted PbI2)is necessary for achieving optimaldevice efﬁciency.©2014Author(s).All article content,except where otherwisenoted,is licensed under a Creative Commons Attribution3.0Unported License.[/10.1063/1.4895038]With the global growth in energy demand and with compelling climate-related environmental concerns,alternatives to the use of non-renewable and noxious fossil fuels are needed.1One such alternative energy resource,and arguably the only legitimate long-term solution,is solar energy. Photovoltaic devices which are capable of converting the photonﬂux to electricity are one such device.2Over the last2years,halide hybrid perovskite-based solar cells with high efﬁciency have engendered enormous interest in the photovoltaic community.3,4Among the perovskite choices, methylammonium lead iodide(MAPbI3)has become the archetypal light absorber.Recently,how-ever,Sn-based perovskites have been successfully implemented in functional solar cells.5,6MAPbI3 is an attractive light absorber due to its extraordinary absorption coefﬁcient of1.5×104cm−1 at550nm;7it would take roughly1μm of material to absorb99%of theﬂux at550nm.Further-more,with a band gap of1.55eV(800nm),assuming an external quantum efﬁciency of90%,a maximum current density of ca.23mA/cm2is attainable with MAPbI3.Recent reports have commented on the variability in device performance as a function of perovskite layer fabrication.8In our laboratory,we too have observed that seemingly identicalﬁlmsa Invited for the Perovskite Solar Cells special topic.b Authors to whom correspondence should be addressed.Electronic addresses:j-hupp@ and m-kanatzidis@2,091101-12166-532X/2014/2(9)/091101/7©Author(s)2014FIG.1.X-ray diffraction patterns of CH3NH3PbI3ﬁlms with increasing dipping time(%composition of PbI2was determined by Rietveld analysis(see Sec.S3of the supplementary material for the Rietveld analysis details).have markedly different device performance.For example,when ourﬁlms of PbI2are exposed to MAI for several seconds(ca.60s),then a light brown coloredﬁlm is obtained rather than the black color commonly observed for bulk MAPbI3(see Sec.S2of the supplementary material for the optical band gap of bulk MAPbI3).23This brown color suggests only partial conversion to MAPbI3and yields solar cells exhibiting a J sc of13.4mA/cm2and a V oc of960mV;these values are signiﬁcantly below the21.3mA/cm2and1000mV obtained by others.4Under the hypothesis that fully converted ﬁlms will achieve optimal light harvesting efﬁciency,we increased the conversion time from seconds to2h.Unexpectedly,the2-h dipping device did not show an improved photovoltaic response(J sc =9.7mA/cm2,V oc=846mV)even though conversion to MAPbI3appeared to be complete.With the only obvious difference between these two devices being the dipping time,we hypothesized that the degree of conversion of PbI2to the MAPbI3perovskite is an important parameter in obtaining optimal device performance.We thus set out to understand the correlation between the method of fabrication of the MAPbI3layer,the precise chemical compositions,and both the physical and photo-physical properties of theﬁlm.We report here that remnant PbI2is crucial in forming a barrier layer to electron interception/recombination leading to optimized J sc and V oc in these hybrid perovskite-based solar cells.We constructed perovskite-containing devices using a two-step deposition method according to a reported procedure with some modiﬁcations.4(see Sec.S1of the supplementary material for the experimental details).23MAPbI3-containing photo-anodes were made by varying the dipping time of the PbI2-coated photo-anode in MAI solution.In order to minimize the effects from unforeseen variables,care was taken to ensure that allﬁlms were prepared in an identical manner.The composi-tions ofﬁnal MAPbI3-containingﬁlms were monitored by X-ray diffraction(XRD).Independently of the dipping times,only theβ-phase of the MAPbI3is formed(Figure1).9However,in addition to theβ-phase,allﬁlms also showed the presence of unconverted PbI2(Figure1,marked with*) which can be most easily observed via the(001)and(003)reﬂections at2θ=12.56◦and38.54◦respectively.As the dipping time is increased,the intensities of PbI2reﬂections decrease with a concomitant increase in the MAPbI3intensities.In addition to the decrease in peak intensities of PbI2,the peak width increases as the dipping time increases indicating that the size of the PbI2 crystallites is decreasing,as expected,and the converse is observed for the MAPbI3reﬂections.This observation suggests that the conversion process begins from the surface of the PbI2crystallites and proceeds toward the center where the crystallite domain size of the MAPbI3phase increases and that of PbI2diminishes.Interestingly,the remnant PbI2phase can be seen in the data of other reports, but has not been identiﬁed as a primary source of variability in cell performance.8,10 Considering that the perovskite is the primary light absorber within the device,we wantedto further investigate how the optical absorption of theﬁlm changes with increasing dipping timeFIG.2.Absorption spectra of CH3NH3PbI3ﬁlms as a function of unconverted PbI2phase fraction.FIG.3.(a)J-V curves and(b)EQE of CH3NH3PbI3-based devices as a function of unconverted PbI2phase fraction.(Figure2).11,12The pure PbI2ﬁlm shows a band gap of2.40eV,consistent with the yellow color of PbI2.As the PbI2ﬁlm is gradually converted to the perovskite,the band gap is progressively shifted toward1.60eV.The deviation of MAPbI3’s band gap(1.60eV)from that of the bulk MAPbI3 material(1.55eV)could be explained by quantum conﬁnement effects related with the sizes of TiO2and MAPbI3crystallites and their interfacial interaction.13,14Interestingly,we also noticed the presence of a second absorption in the light absorber layer,in which the gap gradually red shifts from1.90eV to1.50eV as the PbI2concentration is decreased from9.5%to0.3%(Figure2—blue arrow).Having established the chemical compositions and optical properties of the light absorberﬁlms, we proceeded to examine the photo-physical responses of the corresponding functional devices in order to determine how the remnant PbI2affects device performance.The pure PbI2based device remarkably achieved a0.4%efﬁciency with a J sc of2.1mA/cm2and a V oc of564mV (Figure3(a)).Upon progressive conversion of the PbI2layer to MAPbI3,we observe two different regions(Figure4,Table I).In theﬁrst region,the expected behavior is observed;as more PbI2is converted to MAPbI3,the trend is toward higher photovoltaic efﬁciency,due both to J sc and V oc, until1.7%PbI2is reached.The increase in J sc is attributable,at least in part,to increasing absorption of light by the perovskite.We speculate that progressive elimination of PbI2,present as a layer between TiO2and the perovskite,also leads to higher net yields for electron injection into TiO2and therefore,higher J values.For a sufﬁciently thick PbI2spacer layer,electron injection would occur instepwise fashion,i.e.,perovskite→PbI2→TiO2.Finally,the photovoltage increase is attributable toFIG.4.Summary of J-V data vs.PbI2concentration of CH3NH3PbI3-based devices(Region1:0to15min dipping time, Region2:15min to2h dipping time).TABLE I.Photovoltaic performance of CH3NH3PbI3-based devices as a function of unconverted PbI2fraction.Dipping time PbI2concentration a J sc(mA/cm2)V oc(V)Fill factor(%)Efﬁciency(%) 0s100% 2.10.564320.45s9.5%10.10.93352 4.960s7.2%13.40.96052 6.72min 5.3%14.00.964557.45min 3.7%14.70.995578.315min 1.7%15.1 1.036629.730min0.8%13.60.968648.51h0.4%12.40.938657.62h0.3%9.70.84668 5.5a Determined from the Rietveld analysis of X-ray diffraction data.the positive shift in TiO2’s quasi-Fermi level as the population of photo-injected electrons is higher with increased concentration of MAPbI3.The second region yields a notably different trend;surprisingly,below a concentration of2% PbI2,J sc,V oc,and ultimatelyηdecrease.Considering that the light-harvesting efﬁciency would increase when the remaining2%PbI2is converted to MAPbI3(albeit to only a small degree),then the remnant PbI2must have some other role.We posit that remnant PbI2serves to inhibit detrimental electron-transfer processes(Figure5).Two such processes are back electron transfer from TiO2to holes in the valence band of the perovskite(charge-recombination)or to the holes in the HOMO of the HTM(charge-interception).This retardation of electron interception/recombination observation is reminiscent of the behavior of atomic layer deposited Al2O3/ZrO2layers that have been employed in dye-sensitized solar cells.15–18It is conceivable that the conversion of PbI2to MAPbI3occurs from the solution interface toward the TiO2/PbI2interface and thus would leave sandwiched between TiO2and MAPbI3a blocking layer of PbI2that inhibits charge-interception/recombination.For this hypothesis to be correct,it is crucial that the conduction-band-edge energy(E cb)of the PbI2be higher than the E cb of the TiO2.19–21 The work function of PbI2was measured by ultraviolet photoelectron spectroscopy(UPS)and was observed to be at6.35eV vs.vacuum level,which is0.9eV lower than the valence-band-edge energy(E vb)of MAPbI3(see Sec.S7of the supplementary material23for the work function of PbI2);the E cb(4.05eV)was calculated by subtracting the work function from the band gap(2.30eV).solar cell.FIG.6.Dark current of CH3NH3PbI3-based devices as a function of unconverted PbI2phase fraction.The E cb of PbI2is0.26eV higher than the E cb of TiO2and thus PbI2satisﬁes the conditions of a charge-recombination/interception barrier layer.In order to probe the hypothesis that PbI2acts as a charge-interception barrier,dark current measurements,in which electronsﬂow from TiO2to the HOMO of the HTM,were made.Consistent with our hypothesis,Figure6illustrates that the onset of the dark current occurs at lower potentials as the PbI2concentration decreases.In the absence of other effects,the increasing dark current with increasing fraction of perovskite(and decreasing fraction of PbI2)should result in progressively lower open-circuit photovoltages.Instead,the photocurrent density and the open-circuit photovoltage bothincrease,at least until to PbI2fraction reaches1.7%.As discussed above,thinning of a PbI2-basedFIG.7.Cross-sectional SEM images of CH3NH3PbI3ﬁlm with different dipping time.sandwich layer should lead to higher net injection yields,but excessive thinning would diminish the effectiveness of PbI2as a barrier layer for back electron transfer reactions.Given the surprising role of remnant PbI2in these devices,we further probed the two-step conversion process by using scanning-electron microscopy(SEM)(Figure7).Two domains of lead-containing materials(PbI2and MAPbI3)are present.Theﬁrst domain is sited within the mesoporous TiO2network(area1)while the second grows on top of the network(area2).Area2initially contains 200nm crystals.As the dipping time is increased,the crystals show marked changes in size and morphology.The formation of bigger perovskite crystals is likely the result of the thermodynamically driven Ostwald ripening process,i.e.,smaller perovskite crystals dissolves and re-deposits onto larger perovskite crystals.22The rate of charge-interception,as measured via dark current,is proportional to the contact area between the perovskite and the HTM.Thus,the eventual formation of large, high-aspect-ratio crystals,as shown in Figure7,may well lead to increases in contact area and thereby contributes to the dark-current in Figure6.Regardless,we found that the formation of large perovskite crystals greatly decreased our success rate in constructing high-functioning,non-shorting solar cells.In summary,residual PbI2appears to play an important role in boosting overall efﬁciencies for CH3NH3PbI3-containing photovoltaics.PbI2’s role appears to be that of a TiO2-supported blocking layer,thereby slowing rates of electron(TiO2)/hole(perovskite)recombination,as well as decreasing rates of electron interception by the hole-transporting material.Optimal performance for energy conversion is observed when ca.98%of the initially present PbI2has been converted to the perovskite. Conversion to this extent requires about15min.Pushing beyond98%(and beyond15min of reaction time)diminishes cell performance and diminishes the success rate in constructing non-shorting cells.The latter problem is evidently a consequence of conversion of small and more-or-less uniformly packed perovskite crystallites to larger,poorly packed crystallites of varying shape and size.Finally,the essential,but previously unrecognized,role played by remnant PbI2 provides an additional explanation for why cells prepared dissolving and then depositing pre-formed CH3NH3PbI3generally under-perform those prepared via the intermediacy of PbI2.We thank Prof.Tobin Marks for use of the solar simulator and EQE measurement system. Electron microscopy was done at the Electron Probe Instrumentation Center(EPIC)at Northwestern University.Ultraviolet Photoemission Spectroscopy was done at the Keck Interdisciplinary SurfaceScience facility(Keck-II)at Northwestern University.This research was supported as part of theANSER Center,an Energy Frontier Research Center funded by the U.S Department of Energy, Ofﬁce of Science,Ofﬁce of Basic Energy Sciences,under Award No.DE-SC0001059.1R.Monastersky,Nature(London)497(7447),13(2013).2H.J.Snaith,J.Phys.Chem.Lett.4(21),3623(2013).3M.M.Lee,J.Teuscher,T.Miyasaka,T.N.Murakami,and H.J.Snaith,Science338(6107),643(2012).4J.Burschka,N.Pellet,S.J.Moon,R.Humphry-Baker,P.Gao,M.K.Nazeeruddin,and M.Gratzel,Nature(London) 499(7458),316(2013).5F.Hao,C.C.Stoumpos,D.H.Cao,R.P.H.Chang,and M.G.Kanatzidis,Nat.Photonics8(6),489(2014);F.Hao,C.C. Stoumpos,R.P.H.Chang,and M.G.Kanatzidis,J.Am.Chem.Soc.136,8094–8099(2014).6N.K.Noel,S.D.Stranks,A.Abate,C.Wehrenfennig,S.Guarnera,A.Haghighirad,A.Sadhanala,G.E.Eperon,M.B. Johnston,A.M.Petrozza,L.M.Herz,and H.J.Snaith,Energy Environ.Sci.7,3061(2014).7H.S.Kim,C.R.Lee,J.H.Im,K.B.Lee,T.Moehl,A.Marchioro,S.J.Moon,R.Humphry-Baker,J.H.Yum,J.E.Moser, M.Gratzel,and N.G.Park,Sci.Rep.2,591(2012).8D.Y.Liu and T.L.Kelly,Nat.Photonics8(2),133(2014).9C.C.Stoumpos,C.D.Malliakas,and M.G.Kanatzidis,Inorg.Chem.52(15),9019(2013).10J.H.Noh,S.H.Im,J.H.Heo,T.N.Mandal,and S.I.Seok,Nano Lett.13(4),1764(2013).11Diffuse reﬂectance measurements of MAPbI3ﬁlms were converted to absorption spectra using the Kubelka-Munk equation,α/S=(1-R)2/2R,where R is the percentage of reﬂected light,andαand S are the absorption and scattering coefﬁcients, respectively.The band gap values are the energy value at the intersection point of the absorption spectrum’s tangent line and the energy axis.12L.F.Gate,Appl.Opt.13(2),236(1974).13O.V oskoboynikov,C.P.Lee,and I.Tretyak,Phys.Rev.B63(16),165306(2001).14X.X.Xue,W.Ji,Z.Mao,H.J.Mao,Y.Wang,X.Wang,W.D.Ruan,B.Zhao,and J.R.Lombardi,J.Phys.Chem.C 116(15),8792(2012).15E.Palomares,J.N.Clifford,S.A.Haque,T.Lutz,and J.R.Durrant,J.Am.Chem.Soc.125(2),475(2003).16C.Prasittichai,J.R.Avila,O.K.Farha,and J.T.Hupp,J.Am.Chem.Soc.135(44),16328(2013).17A.K.Chandiran,M.K.Nazeeruddin,and M.Gratzel,Adv.Funct.Mater.24(11),1615(2014).18M.J.Katz,M.J.D.Vermeer,O.K.Farha,M.J.Pellin,and J.T.Hupp,Langmuir29(2),806(2013).19M.J.DeVries,M.J.Pellin,and J.T.Hupp,Langmuir26(11),9082(2010).20C.Prasittichai and J.T.Hupp,J.Phys.Chem.Lett.1(10),1611(2010).21F.Fabregat-Santiago,J.Garcia-Canadas,E.Palomares,J.N.Clifford,S.A.Haque,J.R.Durrant,G.Garcia-Belmonte, and J.Bisquert,J.Appl.Phys.96(11),6903(2004).22Alan D.McNaught and Andrew Wilkinson,IUPAC Compendium of Chemical Terminology(Blackwell Scientiﬁc Publica-tions,Oxford,1997).23See supplementary material at /10.1063/1.4895038for experimental details,absorption spectrum of bulk CH3NH3PbI3,fraction,size,absorption spectrum,work function of unconverted PbI2,and average photovoltaic perfor-mance.。

年产6万吨2丙基庚醇车间合成工段工艺初步设计毕业设计

齐齐哈尔大学毕业设计(论文)题目年产6万吨2-丙基庚醇车间合成工段工艺初步设计学院化学与化学工程专业班级学生姓名指导教师成绩2013 年 6 月日摘要本课题是年产6万吨2-丙基庚醇车间合成工段工艺的初步设计。

第一论述了二丙基庚醇合成的意义与作用、国内外研究现状及进展前景，并简要介绍了二丙基庚醇的性质及合成方式，第二介绍了课题的设计背景、厂址选择和原料产品规格；通过国内外几种相关工艺的比较肯定本设计的工艺流程，对整个生产进程进行了物料衡算、热量衡算和Aspen plus模拟；对反映釜等主要设备进行了设备计算与选型，而且对车间设备进行了布置，对自动控制、安全和环境保护和公用工程进行了概述。

最后按照毕业设计的要求利用AutoCAD绘制戊醛缩合反映釜装配图和合成工段设备平立面布置图，手绘了带控制点的工艺流程图，而且完成了20 000字的毕业设计说明书。

关键词：初步设计；合成工段；2-丙基庚醇；衡算AbstractThe preliminary design of workshop of the synthesis section of 60,000 tons annual production capacity of 2-propyl heptanol was completed. Firstly, the significance, the function of 2-propyl heptanol, the development of research on 2-propyl heptanol was stated. The nature of 2-propyl heptanol and synthetic methods were described briefly. Secondly, the design background, plant location and materials and product specification were introduced; comparion of the productive processed in the domestic and aboard, the design process was determined. Meanwhile the material balance, heat balance, and the simulation of process by Aspen plus were finished. The reactor equipment and other major equipments were calculated and selected. And the layout of the equipment for the workshop, safety, environmental protection and public works were outlined. Thirdly, the equipments arrangement diagram of the workshop and the pentanal condensation reactor equipment were drawn with Auto CAD, the process flow diagram with control points was drawn by hand. Finally, the design instruction of 20 thousand words was finished.Key words：Preliminary design; Synthesis section; 2 - propyl heptanol; Balance calculation目录摘要 (I)Abstract (II)第一章总论 (1)概述 (1)项目建设意义 (1)国内外现状及进展前景 (1)设计依据 (3)厂址选择 (4)厂址肯定 (4)厂址优势分析 (4)设计规模与生产制度 (5)设计规模 (5)生产制度 (5)原料和产品规格 (6)经济核算 (6)第2章工艺设计和计算 (7)工艺线路的选择 (7)2-丙基庚醇工艺介绍 (7)2-丙基庚醇工艺的肯定 (8)工艺流程简述 (8)物料衡算 (9)反映器R101的物料衡算 (9)分离罐V103的物料衡算 (10)换热器E101的物料衡算 (11)精馏塔T101的物料衡算 (12)换热器E104的物料衡算 (12)反映器R102的物料衡算 (13)换热器E105的物料衡算 (14)闪蒸罐V105的物料衡算 (15)热量衡算 (16)反映器R101的热量衡算 (16)换热器E101的热量衡算 (17)T101冷凝器E102的热量衡算 (18)T101再沸器E103的热量衡算 (19)精馏塔T101的热量衡算 (21)换热器E104的热量衡算 (22)反映器R102的热量衡算 (24)换热器E105的热量衡算 (25)全流程模拟 (26)总工艺的模拟 (26)反映器R101的模拟 (27)精馏塔T101的模拟 (28)反映器R102的模拟 (28)第3章设备计算及选型 (30)关键设备R101计算及选型 (30)R101筒体直径和高度的计算 (30)筒体壁厚的计算 (30)夹套的计算 (31)水压实验及强度校核 (32)换热计算 (33)釜体法兰的选择 (33)搅拌器的选择 (33)搅拌传动装置和密封装置的选择 (34)容器支座的选择 (35)人孔、视镜、温度计和工艺接管的选择 (35)其他设备计算与选型 (36)反映器R102的计算 (36)精馏塔T101的计算 (37)换热器的计算与选型 (40)泵计算与选型 (43)储罐和回流罐的计算与选型 (44)紧缩机C101的计算与选型 (46)第4章设备一览表 (47)第5章车间布置 (49)反映器和塔的布置 (49)换热器的布置 (50)泵和紧缩机的布置 (50)罐的布置 (51)第6章自动控制 (52)2-丙基庚醇合成工段自动控制 (52)泵P101的控制 (52)塔顶冷凝器E102的控制 (52)反映器R101的控制 (53)精馏塔T101的控制 (53)第7章公用工程 (55)供水 (55)供热 (55)供电 (56)第8章安全环境保护 (57)结束语 (58)参考文献 (59)致谢 (61)第一章总论概述项目建设意义分子总碳数为4～13的脂肪族伯醇，其全世界近50％产量用于生产增塑剂，所以国内外俗称其为增塑剂醇[1]。

初级英语阅读文章

初级英语阅读文章初级英语阅读文章初级英语的阅读文章有哪些呢?下面是店铺提供给大家阅读欣赏的英语阅读文章。

希望大家喜欢!第一篇：成都熊猫宝宝们集体上演熊猫瘫A panda cub stole the show at a presentation after it tumbled from the stage it was on at the Chengdu Research Base of Giant Panda Breeding.The animals were on display on September 29 as part of a celebration “showing off “ the panda cubs born so far this year.A total of 27 cubs have been born at the base with 23 still residing at the centre in south-wes t China’s Sichuan province.In the footage shows the cuddly panda bears lying on a green stage at the panda base in Chengdu.The cubs seem to be behaving themselves lying on the stage.However one panda on the left hand side seems to have other ideas, making a giant leap for the grass below the stage.The panda appears to land on its head with its legs up in the air.A keeper can be seen running after the cub to try and catch it.Another keeper then tries to space out the animals before another cub tries to make an escape.However it’s too slow with a keeper coming to push it back onto the stage instantly.一只熊猫幼仔在舞台上翻来覆去，抢走了展示的镜头，这一幕在成都大熊猫繁育研究基地上演。

4H 和 6H-SiC的介电常数

a͒Electronic mail: R37595@
II. BULK 4H AND 6H SiC
A. Samples
The 4H and 6H SiC samples studied here were obtained commercially from Cree Research. For spectroscopic ellipsometry, we used single-side polished ͑Si-terminated͒ wafers, 35 mm in diameter, and 0.42 mm thick. The miscut, i.e., the angle between the surface normal and the hexagonal axis, was about 8°, conﬁrmed by x-ray diffraction. The wafers were not intentionally doped, but nitrogen impurities resulted in electron concentrations near 6 – 8ϫ1018 cmϪ3 in 4H SiC and 1ϫ1018 cmϪ3 in 6H SiC, determined by secondary ion mass spectrometry, Fourier-transform infrared ellipsometry, and electrical measurements by the supplier. The samples were measured as received. No surface preparation was performed. Therefore, we expect that the wafers are covered with a thin native oxide (SiO2). Samples used for transmission intensity measurements were similar, but two-side polished.

实验四：介观动力学模拟

《计算材料学》实验讲义粗粒度模拟实验名称：介观动力学模拟一、前言1、介观模拟简介长期以来，化学家致力于从分子水平研究物质及其变化，而化学工程工作者主要研究物质在宏观体系的行为，介观层次的化学正是联系微观及宏观的桥梁，是从分子到材料的必由之路，同生命过程也有密切的关联。

由于介观模拟能够模拟的空间尺度（纳米到微米）、时间尺度（纳秒到微妙）更大，应用介观模拟方法可以模拟更加复杂的体系，例如：高分子熔体，高分子稀溶液自组装，表面活性剂溶液自组装，磷脂膜等胶体化学，高分子，生物大分子相关的内容。

目前介观模拟的方法很多，例如耗散颗粒动力学模拟方法(dissipative particle dynamics，DPD)，它是根据Hoogerbrugge和Koelman提出的一种针对柔性(soft)球模型流体动力学的模拟，并通过引入粒子间的谐振动势，来模拟聚合物的性质；元胞动力学方法（CDS），基于重整化群理论，对时间相关的Ginzburg-Landau方程直接用数值计算的方法在离散空间上进行描述。

其中单个元胞的演化通常用双曲正切函数表示；动态密度泛函方法（DDFT或MesoDyn），应用于高分子体系，建立在粗粒化高斯链模型的基础上，实际上是一个动态的自洽场方法，使用了朗之万方程（Langevin’s equation）来描述体系演化的动力学。

（1）MS-Mesocite简介MS Mesocite是一个基于粗粒度模拟方法的、可以对广泛体系进行模拟研究的分子力学工具集，模拟的对象大小尺寸在纳米到微米尺度范围，相应地，模拟变化的时间范围落在纳秒至微秒区间。

MS Mesocite的模拟对象遍及多种工业领域，比如复合材料、涂料、化妆品以及药物控缓释等，它可以提供流体在平衡态下、在有剪切力存在下以及其它受限制条件下的结构与动力学性质。

MS Mesocite 的突出特点是使用完全区别于传统介观模拟技术，转而采用力场(Forcefield)方法—比如MS Martini力场—来描述粗粒度之间的相互作用，从而得到体系的结构、和动力学特性，分析函数主要有角度分布，密度分布，径向分布函数，二面角分布，均方根位移等。

大学物理化学第二章热力学第二定律学习指导及习题解答

3．熵可以合理地指定
Sm$
(0K)
0
，热力学能是否也可以指定
U
$ m
(0K)
0
呢？
答：按能斯特热定理，当温度趋于0K，即绝对零度时，凝聚系统中等温变化过
程的熵变趋于零，即
，只要满足此式，我们就可以任意
选取物质在0K时的任意摩尔熵值作为参考值，显然 Sm$ (0K) 0 是一种最方便的
选择。但0K时反应的热力学能变化并不等于零，
（2）变温过程
A．等压变温过程始态 A（p1,V1,T1）终态 B（p 1,V2,T2）
S
T2
δQ R
T T1
T2 Cp d T T T1
Cp
ln
T2 T1
B．等容变温过程始态 A（p1,V1,T1）终态 B（p2,V1,T2）
S
T2
δQ R
T T1
C．绝热过程
T2 CV d T T T1
，所以不
能指定
U
$ m
(0K)
0
。
4．孤立系统从始态不可逆进行至终态S＞0，若从同一始态可逆进行至同
一终态时，则S＝0。这一说法是否正确？
答：不正确。熵是状态函数与变化的途径无关，故只要始态与终态一定S
必有定值，孤立系统中的不可逆过程S＞0，而可逆过程S＝0 是毋庸置疑的，
问题是孤立系统的可逆过程与不可逆过程若从同一始态出发是不可能达到相同
4．熵（1）熵的定义式
dS δ QR T
或
S SB SA
B δ QR AT
注意，上述过程的热不是任意过程发生时，系统与环境交换的热量，而必须是在
可逆过程中系统与环境交换的热。

光电化学课件-电化学研究方法第二讲-电极过程动力学的唯像处理

对阴极还原反应, 假设一定时间内外电路传来了n个电子, 但由于界面电荷转移反应相对较慢,这些电子未能在短期内消耗, 这时导致电极上负电荷变多, 这些增加的负电荷通过静电作用使得电极附近溶液侧的正离子数目增加,使得固液界面电势差降低,电极电势负移
j(电流密度)
j(电流密度)
电极电势
原电池中的极化曲线
电解制备和纯化金属如铝 NaCl
H2O
electrolysis
NaOH
1 2
Cl2
除了电压型的传感器(pH计, ISE)外, 大部分电化学装置在工作时, 往往是偏离平衡的条件的
如何评价(偏离平衡条件下工作)电化学装置的性能
指导设计、优化的电化学装置?
以一定电流密度电解水时电解池中的电压分布
2H 2e H2
处理复杂电极过程问题的基本思路
简化的电极反应过程
电子转移面
把握总过程中占主导地位的过程,或者创造条件
使所研究的基本过程在
电极
电荷转移
Os
传质过程电极过程中占主导地位 Ob 电极过程动力学研究
ne
注重电荷传递过程
控制实验条件，可使
Rs 传质过程 Rb 电荷传递过程成为速
OHP面
控步骤.
• 传荷过程 k0 －电荷传递速率 k0 》m 传质过程为速控步骤
浓差、电化学、电阻极化及混合作用下的极化曲线
j 浓差
jl
=电化学+ 浓差
电化学
电阻
=电化学+ 浓差+ 电阻
0
首先必须深刻地从理论上了解构成电极过程的各个基本过程,了解它们影响这些过程的各影响因素以及每个过程本身的主要矛盾,以及它们之间的相互联系

Comsol例题--基于离子浓差极化现象的生物分子富集系统的仿真分析

Point 2 (pt2)
1 On the Geometry toolbar, click Primitives and choose Point.
3 | PRECONCENTRATION OF CHARGES PARTICLES IN A MICRO‐NANO‐FLUIDIC CHANNEL
2 In the Settings window for Point, locate the Point section. 3 In the x text field, type 121.
Rectangle 3 (r3)
6 On the Geometry toolbar, click Primitives and choose Rectangle. 7 In the Settings window for Rectangle, locate the Size and Shape section. 8 In the Width text field, type 60. 9 In the Height text field, type 60.
Point 4 (pt4)
1 On the Geometry toolbar, click Primitives and choose Point. 2 In the Settings window for Point, locate the Point section. 3 In the x text field, type 121. 4 In the y text field, type -H.
13 Click Add. 14 In the Concentration table, enter the following setting: c3 15 Click Study. 16 In the Select Study tree, select Preset Studies for Selected Physics Interfaces>Stationary. 17 Click Done.

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arXiv:cond-mat/9812149v1 [cond-mat.stat-mech] 9 Dec 1998DynamicSimulationsoftheKosterlitz-ThoulessPhaseTransition

B.Zheng∗†,M.Schulz∗andS.Trimper∗∗Universit¨at–Halle,06099Halle,Germany

†Universit¨at–GHSiegen,57068Siegen,Germany

AbstractBasedontheshort-timedynamicscalingform,anoveldynamicapproachisproposedtotacklenumericallytheKosterlitz-Thoulessphasetransition.Takingthetwo-dimensionalXYmodelasanexample,theexponentialdiver-genceofthespatialcorrelationlength,thetransitiontemperatureTKTandallcriticalexponentsarecomputed.ComparedwithMonteCarlosimulationsinequilibrium,weobtaindataattemperaturesnearertoTKT.

PACS:02.70.Lq,75.10.Hk,64.60.Fr,64.60.Ht

TypesetusingREVTEX1TheKosterlitz-Thouless(KT)phasetransitionisanimportantkindofphasetransitionsinnature[1,2].WhenthetemperatureapproachesthetransitiontemperatureTKTfromabove,thespatialcorrelationlengthdivergesexponentially,ratherthanbyapowerlawinasecondorderphasetransition.BelowTKT,thesystemremainscriticalinthesensethatthespatialcorrelationlengthisdivergent.Noreallongrangeorderemergesinthewholetemperatureregime.ImportantexamplesofsystemswithaKTtransitionaretheclassicalXY-typemodels,quantumHeisenbergmodels,harddiskmodelsandotherrelevantﬂuidsystemsaswellasﬁeldtheories.Itiswellknownthatduetotheexponentialdivergenceatthetransitiontemperature,numericalsimulationsofcriticalsystemswithaKTtransitionsuﬀerseverelyfromcriticalslowingdown.Forexample,tocomputethespatialcorrelationlengthofthetwo-dimensionalclassicalXYmodel,evenwiththeclusteralgorithmandtheover-relaxedalgorithmonehasonlyreachedthetemperatureT=0.98,whichisstillfairlyfarfromTKTestimatedtobearound0.89to0.90[3–5].Ifsomequenchedrandomnessisaddedtothesystem,e.g.inthefullyfrustratedXYmodel,thesituationbecomesevenmorecomplicated[6–10].Recentlymuchprogresshasbeenmadeincriticaldynamics.Itisdiscoveredthatuniver-saldynamicscalingbehavioremergesalreadyinthemacroscopicshort-timeregime,afteramicroscopictimescaletmic[11–19].Moreinterestingandimportantisthatthestaticexpo-nentsoriginallydeﬁnedinequilibriumentertheshort-timedynamicscaling.Thisprovidesapossiblewayforextractingtheseexponentsfromtheshort-timedynamicscalingbehavior[19].Sincethemeasurementsarecarriedoutinthemacroscopicshort-timeregime,themethodisfreeofcriticalslowingdown.Suchashort-timedynamicapproachhasbeensystematicallyinvestigatedforcriticaldynamicsystemswithasecondorderphasetransition.IthasbeenﬁrstveriﬁedinthesimpleIsingandPottsmodel[20,21]andrecentlyappliedsuccessfullytogeneralandcomplexsystemsasnon-equilibriumdynamicsystems[22,23],thechiraldegreeoffreedominthefullyfrustratedXYmodel[24]andlatticegaugetheory[25].Thecriticalexponentsaswellasthecriticaltemperaturecanbeextractedeitherfromthepowerlawbehavioroftheobservablesattheearlytimesorfromtheﬁnitesizescaling.Comparedwiththenon-localclusteralgorithms,thedynamicapproachdoesstudythedynamicpropertiesoftheoriginallocaldynamics.However,itisnotclearwhethertheshort-timedynamicapproachcansystematicallygobeyondcriticalsystemswithasecondorderphasetransition,eventhoughﬁrststepapproachorattempthasbeenmadetotheKTtransitionsandthespinglasstransitions[26–29].ForsystemswithaKTtransition,forexample,owingtotheabsenceofsymmetrybreakingandtothefactthatthesystemremainscriticalbelowTKT,aclearsignalasforasecondorderphasetransition[21,19,24]doesnotexistsforthetransitiontemperatureTKT.TheexponentνandTKThavenotbeendetermined.Standardtechniquesdevelopedforthesecondorderphasetransitionsdonotapplyhere.Ontheotherhand,besidestheexponents,whetheronecanobtainothercriticalpropertiesoftheequilibriumstateasespeciallythespatialcorrelationlengthfromtheshort-timedynamicsremainsunknown,evenforsecondorderphasetransitions.Inthiscommunicationweproposeashort-timedynamicapproachtotheKTtransitiontakingthetwo-dimensionalXYmodelasanexample.Fromtheshort-timedynamicscaling,weextractthespatialcorrelationlengthoftheequilibriumstate.Fromthespatialcorrelation

2lengthweestimatethetransitiontemperatureTKTandthestaticexponentν.WithTKTathand,thestaticexponentηanddynamicexponentzareobtainedfrompowerlawbehaviorofthemagnetizationandBindercumulant.TherearenoprinciplereasonstochoosetheXYmodelbutonlybecausethereexistthemostdataofMonteCarlosimulationsinequilibriumforcomparison.TheXYmodelintwodimensionsisdeﬁnedbytheHamiltonian

H=1

<󰀁iSi,x(t)>.(3)

Fromageneralphysicalviewpointoftherenormalizationgrouptransformation,themag-netizationM(t)issubjecttoascalingform

M(t,ξ(τ))=t−η/2zM(1,t−1/zξ(τ)).(4)