Two Pillared-layer Co(II) Metal- organic Frameworks Displaying Pore Modulation by Rodlike Ligands
二维过渡金属硫族材料
二维过渡金属硫族材料英文回答：Two-dimensional (2D) transition metal dichalcogenides (TMDs) are a class of materials that have attracted considerable attention in recent years due to their unique electronic, optical, and magnetic properties. TMDs are layered materials consisting of a single layer of transition metal atoms sandwiched between two layers of chalcogen atoms. The most common TMDs are molybdenum disulfide (MoS2), tungsten disulfide (WS2), and molybdenum diselenide (MoSe2).TMDs have a number of properties that make them promising for a variety of applications. First, TMDs are very thin and flexible, which makes them ideal for use in flexible electronics. Second, TMDs have a high carrier mobility, which means that they can conduct electricity very efficiently. Third, TMDs have a wide bandgap, which makes them ideal for use in optoelectronic devices such aslight-emitting diodes (LEDs) and solar cells.TMDs have been used in a variety of applications, including:Flexible electronics.Optoelectronic devices.Sensors.Catalysts.Energy storage.TMDs are a promising class of materials with a wide range of potential applications. As research on TMDs continues, new and innovative applications for these materials are likely to be discovered.中文回答：二维过渡金属硫族材料。
Bond_Pad_Structure
Auger出現Si可能來源為SiO2 / Si3N4 或Auger打在pad旁之passivation上. 若分析出Cl : 一般皆來自於assembly house. (Cl會腐蝕bond pad) Cl-腐蝕來源 : assembly house 中離子交換的Cl-會腐蝕pad, 使pad有龜裂的現象. 當有Cl時會由pad周圍開始腐蝕的原因 : ClH2 O
Analysis Description
一般金屬作用結合大約僅在20~40 間. Normal pad用Auger分析成份有 : Al / O / C / (F少量) 當over etching時, Auger上會出現F(若F : Al < 1 : 3則pad尚屬正常) Al在Auger上的peak若太小 異常
Bond Pad Structure Analysis introduction
Base Bond Pad Structure
Material Polymide Si3N4 SiO2 TiN Al-Si-Cu TiN Ti SiO2 Thickness
5 um
Passivation Metal Layer
Etching Process Description
(PI) Polymide (密度較高,保護較好) Si3N4 (看起來為黃色) SiO2 TiN Al-Si-Cu
蝕刻利用O2+CF4+SF6 來etching PI / Si3N4 / SiO2 / TiN
BPSG PSG
SiO2+B2O3 SiO2+P2O5(8% or 4%) H3PO4(磷酸) - - - 腐蝕bond pad - - -bond pad變色.
Passivation Description
二硫化钼,二维材料性质
Illustrations of (a) zigzag and (b) armchair MoS2 nanoribbons.
(d) zigzag and (e) armchair MoS2 nanotubes.
水准有限，请各位老师和学长指正！
III. Highlight the current application of fewlayered MoS2 materials.
I.
Discuss the interesting property of fewlayerd MoS2 materials
带隙类型随层数变化
Hybridization between p z-orbitals of S atoms and the d-orbitals of molybdenum atoms and are affected by interlayer interactions. The bands at Γ are more affected by a decrease in layer number 随层数减少，MoS2的带隙类 型由间接带隙变为直接带隙 这使得其在光学探测领域具 有潜力
新技术，仪器的应用：
二维材料制备方法
新原子物理理论：
原子厚度层级理论
[英语学习]化学专业英语前言翻译
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Reactions between hexanuclear manganese pivalate with lanthanide salts (chlorides or nitrates), in the presence of potassium hydroxide, 2-pyridylmethanol and sodium azide leads to formation of a new family of hexaheteronuclear manganese–lanthanide clusters.4.AbstractTwo novel metal–organic frameworks of [M3(ptz)2(N3)4(H2O)2] (M = Zn(1), Cd(2)) (ptz =5-(4-pyridyl)tetrazolate) have been prepared hydro(solvo)thermally by reactions of 4-cyanopyridine and excess NaN3 in the presence of zinc and cadmium chloride, respectively. The overall structure motif of complexes 1 and 2 show pillared layered frameworks and feature an unprecedented 3-nodal network with (3,5,6)-connectivity. The layer is of particular interest as it is constructed by μ1,1–N3− and μ1,1,3–N3−bridging modes, simultaneously. Furthermore, the solid fluorescent properties and TGA were studied.5. AbstractStructural characterization of a new self assembled coordination polymer of Cu II, hexamine (hmt) and benzoate (OBz), [Cu4(OBz)8(hmt)]n (1), reveals that it is a cubic non-interpenetrating diamondoid network formed by the coordination of the μ4-hmt ligand to a linear [Cu2(OBz)4] spacer. The magnetic study reveals that the Cu(II) ions are antiferromagnetically coupled (J = − 323.5 cm−1) through the syn–syn carboxylate bridges.6. AbstractSimple PET chemosensors based on anthracene show a selective turn-on fluorescence sensing for Cu2+. The flexible receptor is favorable for turn-on sensing due to chelation enhanced fluorescence. Interestingly, the turn-on fluorescence sensing for Cu2+ is hardly disturbed by the competitive cations and other highly prevalent species in biological and environmental systems, implying a potential in the biological and environmental applications.Metallacyclodimeric complex of [(Me4en)Pd(L)]2(PF6)4 (Me4en = N,N,N′,N′-tetramethylethylenediamine; L = 1,3-bis(4-pyridyl)tetramethyldisiloxane) is a sensitive container for dioxane via appropriate size effect. The equilibrium between the “included” and “free” dioxane species has been monitored by temperature-dependent 1H NMR spectra.8. AbstractAn unprecedented (ethanol)4 cluster is observed in a photoluminescent silver(I) coordination polymer host, [Ag2(dmt)2(nda)·2EtOH]n (1, dmt = 2,4-diamino-6-methyl-1,3,5-triazine, H2nda =naphthalene-1,4-dicarboxylic acid, EtOH = ethanol). In 1, two pairs of symmetry-related ethanol molecules are hydrogen bonded with each other by OH⋯O hydrogen bonds to form a R44(8) hydrogen bond motif where all the ethanol molecules are proton acceptor and proton donor at the same time. The thermal stability and luminescent behavior of 1 were also discussed.9. AbstractA new 3D sandwich-type MOF named [Zn3(bptc)(H2O)4]·C2H5OH·2H2O (1) (H4bptc =biphenyl-2,5,2',5'-tetracarboxylic acid) was obtained by solvothermal reaction, which represents a rare trinodal (3, 4, 10)-connected topology network. Moreover, the thermal stability, UV–vis absorption spectra and photoluminescent properties of 1 have been investigated as well.10. AbstractThe synthesis and characterization of novel metal-free and cobalt phthalocyanine, peripherally symmetrically derived from2,3,6,7,10,11,13,14-octahydro-5H,9H-4,12-(propanothiopropano)-1,8,15,23,4,12-benzotetrathiodiazacyc loheptadecane-17,18-dicarbonitrile (4) which was prepared by the reaction of1,9-diaza-5,13-dithiocyclohexadecane (3) and 1,2-bis(2-iodoethylmercapto)-4,5-dicyanobenzene (2) wascarried out. The novel compounds were characterized by using elemental analysis, 1H, 13C NMR, IR,UV–vis and MS techniques.11. AbstractA novel cationic dinuclear ruthenium complex [RuCl(HL)(TFTPP)]2 (H2L =2,6-bis(5-phenyl-1H-pyrazol-3-yl)pyridine; TFTPP = tri(p-trifluoromethylphenyl)phosphine) has been synthesized and characterized by 31P{1H} NMR, 1H NMR, elemental analysis and X-ray crystallography. This complex is the first cationic dinuclear ruthenium complex bearing N4 ligand characterized by single crystal X-ray analysis. It exhibits good catalytic activity for the transfer hydrogenation of ketones in refluxing 2-propanol.12. AbstractThree new metal-organic coordination polymers, [Mn(4,4′-bpy)(H2BTCA)(H2O)2](4,4′-bpy) (1),[Na2Co(BTCA)(OXA)]·3H2O (2) and [Na2Co(BTCA)(H2O)2] (3), (H4BTCA =benzene-1,2,4,5-tetracarboxylic acid, H2OXA = oxalic acid) have been synthesized, which are characterized by elemental analysis, infrared spectrum and x-ray crystal diffraction. Complex 1 possesses a 3D polymeric structure, which is comprised of (4,4)-layers. Hydrogen bonds play a dominant role in the construction of the final 3D supramolecule. 1D channels are observed in complex 2, which can be ascribed to pillared-layer motifs.13. AbstractTwo 2-(2-benzimidazolyl)-6-methylpyridine (Hbmp) copper(I) complexes bearing PPh3 and1,4-bis(diphenylphosphino)butane (dppb), namely, [Cu(Hbmp)(PPh3)2](ClO4) (1) and[Cu(Hbmp)(dppb)](ClO4) (2), have been synthesized. X-ray diffraction analysis reveals that the most significant influence of the phosphine ligands on the structures is on the P–Cu–P bond angle. Both two Cu(I) complexes exhibit a weak low-energy absorption at 360–450 nm, ascribed to the Cu(I) to Hbmp metal-to-ligand charge-transfer (MLCT) transition, perhaps mixed with some ILCT character inside Hbmp.The room-temperature luminescences are observed for 1 and 2, both in solution and in the solid state, which originate from the MLCT excited states and vary markedly with the phosphine ligands.14. AbstractA new self-assembly gadolinium(III)–iron(II) complex (Gd2Fe) was synthesized and characterized. Relaxivity studies showed that complex Gd2Fe exhibited higher relaxation efficiency compared with the clinically used Gd-DTPA. In vitro MR images on a 0.5 T magnetic field exhibited a remarkable enhancement of signal contrast for Gd2Fe than Gd-DTPA. The results indicated that Gd2Fe could serve as a potential MRI contrast agent.15. AbstractThe reaction of AgClO4·6H2O with (+/−)-trans-epoxysuccinic acid (H2tes) in the presence of2,6-dimethylpyridine afforded a three-dimensional (3-D) Ag I coordination polymer [Ag2(tes)]∞ (1), which exhibits an unusual 5-connected self-penetrating (44·66)2 topological net (tes =(+/−)-trans-epoxysuccinate). Comparison of the structural differences with our relevant finding, atwo-dimensional (2-D) (4,8)-connected (45·6)2(418·610) coordination polymer [Ag4(ces)2]∞ (S1) (ces =cis-epoxysuccinate), suggests that the carboxyl configuration on the ternary ring backbone of H2tes or H2ces ligand plays an important role in the construction of coordination networks.16. AbstractAn unusual three-dimensional (3D) pillared-layer 3d–4f (Cu+–Sm3+) heterometallic coordination polymer, {Sm2Cu7Br6(IN)7(H2O)5·3H2O}n (1) (HIN = isonicotinic acid), has been successfully synthesized by hydrothermal reaction of Sm2O3, CuBr2, HIN, HClO4 and H2O, and characterized by elemental analyses, IR, PXRD, and single-crystal X-ray diffraction. The structure determination reveals that 1 possesses 3D heterometallic framework constructed upon unprecedented [Cu7Br6]n n+ inorganic layers linked by dimeric Sm2(IN)6 pillars. Additionally, the thermogravimetric analysis and luminescent property of 1 were investigated and discussed.17. AbstractA novel double-Dawson-anion-templated, triangular trinuclear Cu-trz unit-based metal–organic framework [Cu II8(trz)6(μ3-O)2(H2O)12][P2W18O62]·4H2O (1) (Htrz = 1,2,4-triazole), has been hydrothermally synthesized and characterized by routine methods. Compound 1 is the first example of the Cu3-triad triangular unit-based three-dimensional (3D) metal–organic framework templated by double [P2W18O62]6−polyoxoanions. Furthermore, the electrochemical property of compound 1 has been studied.18. AbstractA new three-dimensional terbium-carboxylate framework [Tb4L3(H2O)9]·7H2O (1) [(H4L =4,4′-(hexafluoroisopropylidene)diphthalic acid)] has been hydrothermally synthesized and structurally characterized. The framework contains Tb2 and Tb4 clusters, and exhibits an unprecedented 4-nodal (3,4,5,8)-connected topology. In addition, the thermogravimetric analysis, luminescent and magnetic properties were investigated.19. AbstractThis paper reports two alkaline-earth metal phosphonates with formulae M(4-cppH2)2 [M = Sr (1), Ba (2); 4-cppH3 = 4-carboxylphenylphosphonic acid]. Compound 1 shows a chain structure made up ofedge-sharing {SrO8} polyhedra and {PO3C} tetrahedra. While in compound 2, the edge-sharing {BaO8} polyhedra are connected by the {PO3C} tetrahedra to form a two-dimensional inorganic layer. Neighboring chains in 1 or layers in 2 are cross-linked by hydrogen bond interactions between the protonated carboxylate groups, resulting in three-dimensional supramolecular structures. The magnesium alloys coated with 1 or 2 films show significantly improved anti-corrosion behaviors compared to the bare substrate.20. AbstractA novel 3D inorganic–organic hybrid compound {[Cu3(en)(TTHA)(H2O)42O}n(1) (TTHA =1,3,5-triazine-2,4,6-triamine hexaacetic acid; en = ethylenediamine) has been synthesized andcharacterized. Topological analysis shows that the compound is a new 3,10-connected 2-nodal net with point symbol (418.624.83)(43)2, further simplification of the structure by merging two 3-connected nodes and one 10-connected node together gives a rare uninodal 8-connected hex net, we conclude that the2-nodal net found in the network is a hex-originated supernet. TG, IR, PXRD and photoluminescent spectra of the compound 1 are investigated.21. AbstractUnder hydrothermal conditions, Sm(NO3)3·6H2O reacts with N-(2-Hydroxyethyl)iminodiacetic acid(H3heidi), oxalic acid (H2Ox), in the presence of NiCl2·6H2O and NaOH, producing a novel two dimensional coordination polymer with the empirical formula of Na[Sm(Hheidi)(Ox)]·2H2O (1). X-ray diffraction analyses show that 1 crystallizes in the orthorhombic system, P na21 space group, a =25.9008(19) Å, b = 6.2593(5) Å, c = 8.7624(6) Å, in which the network of SmNO8 and oxalate units forms an extended two dimensional layered structure. To the best of our knowledge, 1 represents the first structurally characterized lanthanide complex containing H3heidi ligand. The variable-temperature magnetic property of 1 has been investigated and the results of magnetic determination suggest the existence of a weak antiferromagnetic coupling between the samarium ions.22. AbstractHeating [WO2(S2CNBu i2)2] with a slight excess of ArNCO (Ar = Ph, p-tolyl) results in the rapid formation of imido-ureato complexes [W(NAr){κ2-ArNC(O)NAr}(S2CNBu i2)2], a transformation believed to occur via the bis(imido) intermediates [W(NAr)2(S2CNBu i2)2]. The ureato ligand is easily removed (as the urea) upon addition of gaseous HCl to afford the dichloride [W(NAr)Cl2(S2CNBu i2)2]. While bis(imido) complexes are unavailable from the direct reaction of isocyanates (or amines) with [WO2(S2CNBu i2)2], they can be prepared upon addition of dithiocarbamate salts to [W(NBu t)2(NHBu t)2] addition of two equivalents of [NH2Bu i2][Bu i2NCS2] affording [W(NBu t)2(S2CNBu i2)2] in which both imido groups are linear.23. AbstractA new neutral dimeric cyclometalated iridium complex containing bridging thiocyanate ligands,[{Ir(μ-SCN)(pqcm)2}2] (1, pqcmH = 2-phenyl-quinoline-4- carboxylic acid methyl ester), has been synthesized and structurally characterized. The photoluminescence (PL) spectrum of 1 shows emission maximum at 638 nm with a lifetime of 0.11 μs and the PL quantum yield is c. The phosphorescence behaviours of 1 towards different solvents and metal ions were also investigated and the strong phosphorescence quenching by acetonitrile and two equivalents of Hg2+, Cu2+ and Ag+ ions were observed.24. AbstractIonothermal reaction of isophthalate (H2ip), and colbolt(II) nitrate under 1-ethly-3-methylimidazolium bromide (EMimBr) as solvent leads to a novel three dimensional metal–organic framework(EMim)2[Co3(ip)4] (1). It can be described as an eight-connected CsCl-type net (42464) utilizing trinuclear Co(II) clusters as eight-connected nodes and ip ligands as linkers. The imidazolium cation [EMim]+ of the ionic liquid acting as charge-compensating agents has interactions with the framework. The magnetic properties studies show ferrimagnetic behavior for 1.25. AbstractUsing the deprotection–realkylation methodology, a new electroactive tetrathiafulvalene-based bipyridine ligand,5-[{2-[4,5-Bis(methylthio)-1,3-dithiol-2-ylidene]-5-(methylthio)-1,3-dithiol-4-yl}thio]-methyl-2,2′-bipyridine (L), has been synthesized. Reactions of the above ligand with Re(CO)5Br or Re(CO)5Cl afford the corresponding tricarbonyl rhenium(I) complexes ReL(CO)3X (X = Br, 1; X = Cl, 2), respectively. Crystal structures of 1 and 2 have been described. The absorption properties of these new compounds have been studied. Electrochemical measurements have been performed and TTF/TTF+•/TTF2+ redox processes are observed.26. AbstractThree carbon-bridged bis(phenolate) neodymium complexes, [(MBMP)2Nd(μ3–Cl)Li(THF)2Li(THF)] (1), [(MBBP)2Nd(μ3-Cl)Li(THF)2Li(THF)] (2) and [(THF)2Nd(EDBP)2Li(THF)] (3) have been synthesized by one-pot reaction of NdCl3 and LiCH2SiMe3with 6,6′-methylenebis(2-tert-butyl-4-methylphenol)(MBMP-H2), 6,6′-methylenebis(2,4-di-tert-butylphenol) (MBBP-H2) or 6,6′-(ethane-1,1-diyl)bis(2,4-di-tert-butylphenol) (EDBP-H2), respectively, in a molar ratio of 1:4:2. The definitive structures of complexes 2 and 3 were determined by X-ray diffraction studies. Experimental results show that 1–3 efficiently initiate the ring-openin g polymerization (ROP) of ε-caprolactone and ROP of L-lactide.27. AbstractA 3D metal-organic framework {[Cd2(TZ)3(BDC)]·5H2O}n (1·5nH2O) (HTZ = 1H-tetrazole, H2BDC =1,4-benzenedicarboxylic acid), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The phase purity was confirmed by powder X-ray diffraction (PXRD), and the stability was identified by thermal gravimetric analysis (TG) and variable-temperature powder X-ray diffraction (VT-PXRD). The result of the single-crystal X-ray diffraction analysis indicates that 1 is a novel 3D microporous metal-organic framework constructed from Cd(II) metal centers and mixed linkers of TZ−anions and BDC2− anions. Photoluminescent measurement elucidates that 1 displays a strong and broad emission peak at 423 nm, which suggests that 1 may be a potential purple-light material.28. AbstractTwo inorganic–organic hybrids, (MPDA)2n(Pb3I10)n (MPDA = p-Me3NC6H4NMe3) (1) and(H2EPDA)n(Pb2I6)n·2n H2O (H2EPDA = p-Et2NHC6H4NHEt2) (2), have been solvothermally synthesized using p-phenylenediamine (PDA) as a precursor. Their iodoplumbate ions all show 1-D chain structures, but differ in interlinkage modes of [PbI6] octahedra: the former is both face- and edge-sharing, while the latter is face-sharing. The chain-like structure in 1 was reported only once in the literature. The results of optical absorption spectra and theoretical calculations for compounds PbI2 and 1–2 reveal a quantum confinement effect. Photoluminescent analyses show that they all exhibit blue emissions upon UV irradiation, which mainly originate from charge transfer from iodine atoms to ammoniums.29. AbstractPlatinum(II) complexes, [Pt(PDTC)(H2O)Cl] and [Pt(PDTC)(DMSO)Cl] (1) (PDTC = pyrrolidinedithiocarbamate) have been prepared and characterized by IR, NMR and X-ray crystallographic methods. In the crystal structure of 1 the central platinum atom is coordinated to two sulfur atoms of PDTC, one sulfur atom of DMSO and one chloride ion adopting a square planar geometry with the average cis and trans bond angles of 90.00° and 171.62° respectively. The 1H and 13C NMR spectral data indicate the coordination of both PDTC and DMSO to platinum(II). The title complex was screened for antimicrobial effects and the results show that it exhibits significant activity againstgram-negative bacteria (E. coli, P. aeruginosa), while the activities are moderate against molds (A. niger, P. citrinum) and yeasts (C. albicans, S. serevisaiae).30. AbstractA new stable mixed-ligand metal organic framework Zn2(tpt)2(2-atp)I21 (tpt = tris (4-pyridyl) triazine, 2-atp = 2-aminoterephthalate) with split channels has been synthesized and characterized. The nitrogen containing ligands tpt and 2-atp are selected to create attractive basic sites for the catalyst. The Knoevenagel condensation between benzaldehyde and the active hydrogen compound (ethyl cyanoacetate or malononitrile) is carried out using compound 1 as solid basic catalytic support. The test results indicate that 1 is an efficient base catalyst with selective catalytic properties. It gives 37% and 99% yield respectively for the condensation products ethyl (E)-α-cyanocinnamate and2-benzylidenemalononitrile. TG data show that the solid catalyst sample is fairly thermally stable. The compound does not show any signs of decomposition until 420 °C. PXRD data support that the catalyst remains its crystalline and framework stability after the catalysis process. These characters make it easily to be regenerated for the next cycle.31. AbstractA heteroleptic nickel-bis-1,2-dithiolene ion–pair complex, [BzQl][Ni(dmit)(mnt)] (where BzQl+ =1-(benzyl)quinolinium; dmit2− = 2-thioxo-1,3-dithiole-4,5-dithiolate, mnt2− = maleonitriledithiolate), was synthesized and characterized structurally, which exhibited novel magnetic bistability. The compound crystallized in triclinic system with space group P-1. The anions and cations form alternating layered alignments, and the anionic layer is built by the irregularly heteroleptic [Ni(dmit)(mnt)]− chains, where theneighboring anions are connected via lateral-to-lateral S…S contacts of dmit2− ligands. The temperature dependences of magnetic susceptibility follow the S = ½ Heisenberg alternating linear-chain model in high-temperature phase and Curie–Weiss law in low-temperature phase.32. AbstractA novel two-dimensional (2D) Mn(II) coordination polymer [Mn(H2bdc)(DMA)2] (1; H2bdc = terephthalic acid; DMA = N,N′-dimethylacetamide) based on trinuclear manganese subunit has been solvothermally prepared and structurally characterized by single-crystal X-ray diffraction. Compound 1 exhibits a rare layered structure with 6-connected hxl topology constructed from the trinuclear Mn3(COO)6 units, and further stacking of layers leads to a 3D supramolecular framework. The thermalgravimetric behavior and magnetic property of 1 have been also investigated. The magnetic susceptibility measurements reveal that the compound exhibits antiferromagnetic coupling interactions.33. AbstractA new salicylaldehyde derivative 1, i.e. 5-chloro-3-(ethoxymethyl)-2-hydroxybenzaldehyde, has been prepared and structurally characterized. A novel dinuclear copper(II) complex of its air-oxidized product 2 has been successfully yielded from the in situ copper(II) ion catalysis and complexation. Additionally, another control experiment has been carried out by using 3,5-dibromo-2-hydroxybenzaldehyde as the starting material, and a similar mononuclear air oxidation copper(II) complex 3 is obtained, where3,5-dibromo-2-hydroxybenzaldehyde has also been in situ transformed to the divalent anion of3,5-dibromo-2-hydroxybenzoic acid.34. AbstractSelf-assembly of CdCl2 and 1,2,4-triazole under hydrothermal condition yields a novel three-dimensional coordination polymer, namely {[Cd8Cl4(Trz)12(H2O)]·2H2O}n (1) (Trz = 1,2,4-triazole). Single-crystal X-ray diffraction reveals that four of the five independent Cd centers are linked by two μ2-Cl and two μ3-Cl atoms to form novel heptanuclear [Cd7Cl4] clusters, which are connected by the bridging water molecules to generate an unprecedented 1D castellated inorganic chain. Furthermore, the fifth unique Cd centerand the castellated Cd–Cl–O chain are joint to each other via six different μ3-Trz ligands to give a 3D organic–inorganic hybrid framework of 1.。
一次、二次枝晶间距模型最经典文献
Prediction of Dendrite Arm Spacing for Low Alloy Steel Casห้องสมุดไป่ตู้ing Processes
M. EL-BEALY and B.G. THOMAS Simple mathematical expressions to predict the primary dendrite arm spacing (PDAS) and secondary dendrite arm spacing (SDAS) suitable for steel casting processes are presented. The equations of the PDAS and SDAS were based on previously published experimental data for low alloy steels. Good agreement was obtained between previous measurements of dendrite arm spacing (DAS) and model predications in the range of cooling rate occurring in steel casting processes. The results indicated that the cooling rate and carbon content basically govern the calculation of PDAS, especially for low carbon steel, However, the carbon content governs the selection of mathematical expression to predict SDAS for low alloy steels. Dendritic growth is the most common crystallization mechanism in industrial steels. Many descriptive studies characterize the microstructure of metal alloy solidification in terms of the dendrite morphology. The dendrite morphology defines a dendrite as composed of primary, secondary, and higher order arms.m The fineness of the dendritic structure affects microsegregation and inclusion formation, which leads to a deterioration in mechanical properties.I:1 Most of the published work concerning dendrite arm spacing (DAS) has involved the postmortem examination of solidified steel ingots in which the solidification conditions have been only partially controlled.13-rl It is generally agreed that both thermal conditions and alloy content affect the structure of cast steel alloys. The measured parameter has been the local cooling rate, or the local solidification time, whereas the local dendrite tip velocity and temperature gradient were unknown. Nevertheless, these experiments have contributed greatly to our understanding of dendrite morphology. A few attempts have been made to control solidification more precisely by establishing steadystate columnar dendrite growth conditions with controlled growth velocities and the known temperature gradientJ 7.8,9j Increasing the cooling rate is known to reduce both the primary dendrite arm spacing (PDAS) and the secondary dendrite arm spacing (SDAS). u 91 Also, it has been shown
双层MoS2
斯异质结。 基于密度泛函理论的第一性原理计算结果表明,ML MoS2 / VS2 和 BL MoS2 / VS2 异质结均表现出 p
型肖特基势垒,但在由 BL MoS2 构成的异质结中,肖特基势垒高度显著降低,仅为 0. 08 eV,十分接近于欧姆
接触的形成。 此外,通过对两种异质结光吸收光谱的计算,发现 BL MoS2 / VS2 异质结的介电函数的实部和虚
膜材料 [9-11] 。 目前为止,基于二维 MoS2 纳米片的场效应晶体管和数字电路已被成功制造。 值得关注的是,
在纳米电子器件中引入二维 MoS2 纳米片不可避免地涉及到与金属的接触,而相应的接触性质将会显著影响
器件的性能 [12-14] 。 因此,如何在金属半导体界面有效地降低接触电阻,对设计高性能纳米电子器件具有重
Key words: density functional theory; MoS2 ; electronic structure; van der Waals heterojunction; Schottky barrier;
light absorption
0 引 言
近年来,以石墨烯为代表的二维纳米材料因其独特的机械和电子性能而得到了广泛的研究与应用 [1-5] 。
用于描述交换关联作用 [18] ,投影缀加平面波方法被用来考虑离子与电子间相互作用。 平面波展开的截断能
被设置为 500 eV,采用 11 × 11 × 1 的 K 点网格在布里渊区进行取样,能量和力的收敛标准分别为 10 - 5 eV、
0. 01 eV / Å。 为避免相邻晶格之间的相互作用,真空层被设定为 15 Å 以确保消除层间的相互影响。 在非对
that the heterojunction composed of bilayer MoS2 has higher absorption peaks. The research results provide a theoretical basis
第六章金属化（Thesixthchapterismetallization）
第六章金属化（The sixth chapter is metallization）The sixth chapter is metallization and multilayer interconnection technologyMetal and metal materials1. divide by functionPart of the MOSFET gate electrode material MOSFET devices, plays an important role in the performance of the device.Interconnecting materials - connecting individual components of the same chip to a circuit module with certain functions.Contact materials - materials that come directly into contact with semiconductor materials and provide contact points externally connected.2. commonly used metal materials: Al, Cu, Pt, Au, W, Mo and so on3. atmospheric metallic materials: doped poly-Si, metal silicide (PtSi, CoSi), metal alloys (AuCu, CuPt, TiB2, ZrB2, TiC, MoC, TiN)The sixth chapter is metallization and multilayer interconnection technologyTwo. Basic requirements for metallization of integrated circuits1. to P +, N + or poly-Si to form a low resistance ohm contact, that is, silicon / metal contact resistance as small as possible;2. provide low impedance interconnects to increase the speed of the integrated circuit;3. electromigration resistance;4. good adhesion;5. corrosion resistance;6. easy to deposit and etch;7. easy bonding;The insulation between the 8. layers is better than that of the other, i.e., a diffusion barrier is required.The sixth chapter is metallization and multilayer interconnection technologyThree ohm contact1. definition: metal - relative to the semiconductor body or series resistance, when the contact resistance of semiconductor contact can be ignored, the timing is called ohmic contact.2., three important parameters:Work function: the energy difference between Fermi energy and vacuum energy levelThe work function of metal - Semiconductor work function WS WM.The Schottky barrier height is phi b: Phi B = WM-,Contact resistance RC:RC= (dV/dJ) v=0Low doping: A*- Richard Xun constantThree ohm contactHigh doping:,3. method of forming ohmic contactsLow barrier ohmic contact: the metal work function WM is less than n semiconductor work function WS or the metal work function WM is higher than the P semiconductor work function WS.Reality: must be less than 0.3eV to form ohmic contacts. (because of the existence of a semiconductor surface state, there is a wide depletion layer)Application example: test probeThree ohm contactHigh composite ohmic contact: high concentration defects onsemiconductor surface play the role of composite center in the surface depletion region, and reduce RC obviously.Process: semiconductor surface grinding or sandblasting treatment, ion implantation.Application: backside metallization of power tubes; contact electrodes.Three ohm contactHigh doping ohmic contact: the high diffusion layer is formed on the surface of semiconductor, and only a thin depletion zone is formed in the gold half contact, and the carrier can pass through the barrier through tunneling.Process: carrier concentration is greater than 1019 /cm3, and depletion region width is less than 10nm.Application example: lead holeThe sixth chapter is metallization and multilayer interconnection technologyFour, the realization of metallization1. vacuum evaporation depositionResistance heating evaporation: uses a refractory metal resistance wire (W) or a resistor (Mo) to heat the evaporation source so that it evaporates and is deposited on the surfaceof the silicon wafer.Deposited metal: Al, Au, Cr, etc, easy to fuse and gasifying metals.Electron beam evaporation: a high voltage accelerating and focusing electron beam is used to heat the evaporation source so that it evaporates and is deposited on the surface of the silicon wafer.Deposited metal: refractory metal at melting point >3000 degrees C.Four, the realization of metallization2. sputtering depositionDefinition: the process of bombarding the target atoms from the rake surface and depositing them on the substrate material by bombarding the target with nuclear energy ions.The sputtering material is called the target material as the cathode, while the silicon chip is used as the anode grounding.The mechanism of inert gas after vacuum pumping, electrons accelerate in the electric field, the collision with the inert gas, inert gas ions and produce more electrons, and the inert gas ions hit the target when the thin film is formed on the anode substrate is deposited atom sputtering rake.Four, the realization of metallizationTypesDC sputteringMagnetron sputteringRF sputteringIon beam sputtering and reactive metalsFig. 8-5 schematic diagram of flat magnetron sputtering sourceBecause of the strong magnetic field on the cathode surface, the electrons are limited by the Lorenz forceIn the shadow area, motion along a trajectory similar to a cycloid (dotted line) adds electronsThe number of collisions with the gas increases the density of the plasma and increases the sputtering rate.Four, the realization of metallizationSputtering condition:Substrate temperature: 200~230 DEG c;Background: 3 * 104Pa vacuum;Ar air pressure: 0.3Pa;Sputtering rate: 1.5nm/s.Five 、 aluminum silicon contact1. alloying principle: aluminum and silicon (RE doped 1019) above 300 degrees of temperature can be formed at the interface of silicon aluminum alloy, thus forming the ohmic contact of semiconductor and metal.Aluminum silicon alloy process: 500 DEG C (577 DEG C eutectic melting point), 10 ~15 minutes。
第5章 金属原子簇和金属多重建-3h
Cl
d3
Inorg. Chem. 39(1998)5710-5720
多重键缩短比(多重键键长 单键键长 多重键缩短比 多重键键长/单键键长 多重键键长 单键键长)
Bond C N C N Ratio 0.783 0.786 Bond Cr Mo Re Cr Mo Re Ratio 0.767 0.807 0.848
vx12v为中心金属的价电子数x为配体提供的总电子数根据分子片的总电子数及配体co的总电子数计算总骨架电子数也可以用总电子数tec规则计算tec金属总价层电子数配体提供的电子总数总骨架电子数tec12金属原子数当电子数为2n22n42n6骨架电子数规则or电子对数为n1n2n3骨架电子对数规则对应的结构分别为
[Re2Cl8]2- + PMe3 (惰性气氛，苯溶剂）→ 1,2,5,7-Re2Cl6(PMe3)4 惰性气氛， 惰性气氛 苯溶剂） (+3) 级键） σ2 π4 δ2 (4级键） 级键 (+3)
Re—Re 3.8486Å
不存在金属-金属键 不存在金属 金属键
[Re2Cl8]2- + PEt2H ( HCl，苯 ）→ 1,2,5,6-Re2Cl4(µ-PEt2)(PEt2H)4 ， µ
Cl Cl Re Cl Cl
Cl Re
Cl
H2O Cr Cr OH2 O
CH3 C O
Cl Cl
Re2Cl82– 四方棱柱构形
Cr2Ac4.2H2O
σ π
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5个d轨道形成的 个 σ键，2个π键， 2个δ键 个 轨道形成的 轨道形成的1个 个 个
dx2-y2轨道和dxy的形成 个δ键 轨道和 的形成2个
metal ions (Cu2+, Ni2+, Pb2+) onto ACCs using surface complexation models
Modeling the adsorption of metal ions (Cu 2 ,Ni 2 ,Pb 2 )onto ACCs using surface complexation modelsCatherine Faur-Brasquet *,Zacaria Reddad,Krishna Kadirvelu,Pierre Le CloirecEcole des Mines de Nantes-GEPEA,4rue A.Kastler,44307Nantes Cedex 3,FranceAbstractActivated carbon cloths (ACCs),whose ef®ciency has been demonstrated for microorganics adsorption from water,were here studied in the removal of metal ions from aqueous solution.Two ACCs are investigated,they are characterized in terms of porosity parameters (BET speci®c surface area,percentage of microporosity)and chemical characteristics (acidic surface groups,acidity constants,point of zero charge).A ®rst part consists in the experimental study of three metal ions removal (Cu 2 ,Ni 2 and Pb 2 )in a batch reactor.Isotherms modeling by Freundlich and Brunauer±Emmett±Teller (BET)equations enables the following adsorption order:Cu 2 >Ni 2 >Pb 2 to be determined for adsorption capacities on a molar basis.It may be related to adsorbates characteristics in terms of electronegativity and ionic radius.The in¯uence of adsorbent's microporosity is also shown.Adsorption experiments carried out for pH values ranging from 2to 10demonstrate:(i)an adsorption occurring below the precipitation pH;(ii)the strong in¯uence of pH,with a decrease of electrostatic repulsion due to the formation of less charged hydrolyzed species coupled with a decrease of activated carbon surface charge as pH increases.The second part focuses on the modeling of adsorption versus the pH experimental data by the diffuse layer model (DLM)using Fiteql software.The model is ef®cient to describe the system behavior in the pH range considered.Regarding complexation constants,they show the following af®nity for ACC:Pb 2 >Cu 2 >Ni 2 .They are related to initial concentrations used for the three metal ions.#2002Elsevier Science B.V .All rights reserved.PACS:68.45.DKeywords:Adsorption;Activated carbon cloths;Heavy metals;Water treatment;Surface complexation models1.IntroductionEnvironmental pollution due to heavy metals is caused by various industries,namely metal plating,mining,painting,or agricultural sources like fertili-zers or fungicidal sprays [1].The presence of the above metals in the environment is of major concern because of their toxicity and threat for human life andfor the environment,especially when tolerance levels are exceeded [2].In application of the ``principle of precaution'',relayed at the Rio Conference in 1992,a decrease of water standards relating to metal pollution is provided for.For example,French reglementations for drinking water set the ef¯uent quality standard for lead from 50to 10m g l À1in 2003.In this context,the search for new technologies to remove metals from wastewaters has become a major topic of research.Among the methods commonly used for this purpose,adsorption was shown to be econom-ically favorable (compared with ion exchange,liquidApplied Surface Science 196(2002)356±365*Corresponding author.Tel.: 33-2-51-85-8294;fax: 33-2-51-85-82-99.E-mail address:catherine.faur@emn.fr (C.Faur-Brasquet).0169-4332/02/$±see front matter #2002Elsevier Science B.V .All rights reserved.PII:S 0169-4332(02)00073-9extraction or electrodialysis)and technically easy (compared with precipitation or reverse osmosis)[3]. Activated carbon cloths(ACCs)belong to new technologies appeared for the last decade.Their inter-esting properties for microorganic pollutants removal from water were demonstrated by previous researches [4±7].On one hand,adsorption velocities were2±20 times higher than those obtained with a granular activated carbon due to their high external surface area.On the other hand,adsorption capacities ranged between150and400mg gÀ1for more than60micro-organics.However,their adsorption performance for inorganics treatment has not yet been studied. This study focuses on their ability to remove metal ions from water,and it is divided into three parts.The ®rst part consists in a characterization of physico-chemical properties of activated carbons used in this work.The second part is an experimental study of three metal ions(Cu2 ,Ni2 ,Pb2 )adsorption by mon models(Freundlich,Brunauer±Emmett±Teller(BET))are applied to isotherm curves and the in¯uence of pH is investigated.Then,the third part investigates the ability of a surface complexation model(SCM),the diffuse double layer model,to describe metals removal by ACC as a function of pH.This kind of models was originally proposed to describe the interactions of metal ions with natural oxides by explicitly incorporating solution speciation and reaction stoechiometry for the formation of surface complexes[8].It was successfully applied by several authors to describe the metals sorption phenomena onto various media,namely metal hydro-xides[9,10],soils[11],peat[12],wheat bran[13]or activated carbon in the form of powder or granules [14±16].However,it was never applied to the woven form of activated carbon.2.Materials and methods2.1.Activated carbon clothsTwo ex-rayon ACCs,CS-1501and RS-1301(Actitex company,Levallois,France),were used in this study. In order to explain the adsorption mechanism of metal ions,and to enable a modeling of adsorption data versus pH using SCMs,physico-chemical properties of the adsorbents were determined.Porosity properties were assessed by N2adsorption at77K using a Coulter SA3100apparatus.Concern-ing chemical properties,Boehm's titration method [17]was used to determine the acidic surface groups concentrations.A previous study had shown the amphoteric character of activated carbons which con-tain one type of amphoteric surface hydroxyl groups B S±OH,were S is the activated carbon surface[18]. Potentiometric titrations were thus performed to assess the global surface acidity(intrinsic acidity constant values)according to previously described methods,which consists in®tting the titration curves using Fiteql software[19,20].The potentiometric measurements were carried out at20Æ18C under a nitrogen stream to avoid carbon dioxide dissolution in the solution.A TIM900radiometer titrimeter was used,provided with a glass electrode and an automatic burette.Five hundred milligram of activated carbon were stirred for2days in100ml of NaCl0.1M(solid concentration of5g lÀ1),until pH remained constant. Titrations were performed with NaOH or HCl0.1M, by de®ning a drift reading less than10mV for10s between two titrant additions.2.2.AdsorbatesThree metal ions,copper Cu2 ,nickel Ni2 and lead Pb2 were studied.Stock solutions with a1g lÀ1 concentration were prepared by dissolving commer-cially available metal salts in1%HNO3solutions to prevent hydrolysis formation.They were diluted with distilled water to obtain standard solutions with con-centrations ranging from0.1to1.4mmol lÀ1.Main properties of adsorbates are summarized in Table1. All analyses were carried out with a Perkin-Elmer 2280atomic absorption spectrophotometer.Table1Main properties of metal ionsProperty Cu(II)Pb(II)Ni(II) Molecular weight(g molÀ1)6420759 Salt used to prepare stocksolution(Aldrich)CuSO4PbCl2NiCl2 (purity,%)>9898>99.9 Solubility of the salt(mol lÀ1) 1.250.0357 4.85 Ionic radius(AÊ)0.70 1.120.69 Pauling electronegativity 2.00 1.87 1.91C.Faur-Brasquet et al./Applied Surface Science196(2002)356±3653572.3.Adsorption in a batch reactorAdsorption isotherms of the three metal ions were carried out on both ACC at20Æ18C and for a pH value of5.Initial metal ion concentration ranged between10and70mg lÀ1(i.e.0.1±1.4mmol lÀ1), for a solution volume of250ml and a constant acti-vated carbon weight of500mg.A stirring time of12h was shown to be high enough to reach an equilibrium [18].The dependence of adsorption on pH was studied by adjusting the initial pH values from2to10with NaOH and HCl0.1M.Two hundred and®fty milliliter of metal ion solutions of20and40mg lÀ1and activated carbon weight of500mg were used.In all the cases, ionic strength was not®xed.3.Theory3.1.Surface acidityof activated carbonsThe amphoteric character of activated carbons was shown by previous researches on GAC[14±16]and on the ACC of this study[18],and it may be described by the following ionization reactions of surface sites B SOH:B SOH2 6B SOH HB SOH6B SOÀ H (1) whose intrinsic surface acidity constants,taking into account an electrostatic correction term,are de®ned respectively byK a1 f B SOH gf H gf B SOH2 gexpÀF c0RT(2)K a2B SOÀf g Hf gB SOHf gexpÀF c0RT(3)where R is the molar gas constant(8.314J molÀ1KÀ1), F the Faraday constant(96.485C molÀ1),T the tem-perature(K),c0the potential at the surface(V)and{} represents the activity(mol kgÀ1).3.2.Surface complexation modelsSCMs are surface chemical equilibrium models which originate from work with metal oxides.The basic premise of SCM is that the adsorption of ions onto hydrous solids is analogous to the formation of soluble complexes according to the following single metal±surface complexation reaction:B SOH M2 6B SOM H (4) whose equilibrium constant is de®ned byK int B SOMf B SOM gf H gf B SOH gf M2 gexpÀF c0RT(5)Various types of SCMs were used to model metal sorption onto hydrous solids,namely the diffuse layer model(DLM)[21],the constant capacitance model [22],the Stern model[23]and the triple layer model (TLM)[8].They differ in complexity from the sim-plest,DLM,which has four adjustable parameters,to the most complex,TLM,which includes seven adjus-table parameters.The number of parameters is depen-dent on hypothesis relative to the model[24].In this work,the DLM was selected because of its simplicity and of its applicability to various solution conditions [24].It takes into account ionic strength effects on protolysis equilibria through the Gouy±Chapman±Stern±Grahame charge±potential relationship.s08RT ee0IÂ103psinhZF c02RT(6)where s0is the surface charge(C mÀ2),e the dielectric constant of water(78.5at258C),e0the permittivity of free space(8:854Â10À12C VÀ1mÀ1),Z the valency of the electrolyte and I the ionic strength(mol lÀ1). The four parameters which have to be determined to enable surface complexation computation using Fiteql program from adsorption versus the pH curves[20] are:surface acidity constants de®ned by Eqs.(2)and (3),the total number of acidic surface sites assessed by the Boehm method,and the speci®c surface area determined by nitrogen adsorption at77K.In addition to free metal ion M2 ,inorganic species (e.g.M(OH) ,M(OH)2,M2(OH)22 )may be included in the equilibrium constant calculations,using the formation constants compiled by Smith and Martell [25].Speciation diagrams were assessed for each metal ion for a concentration of30mg lÀ1using Specia software(see Appendices),and it was veri®ed that no shift of speciation diagram was observed for a higher concentration(70mg lÀ1).358 C.Faur-Brasquet et al./Applied Surface Science196(2002)356±3654.Results and discussion4.1.Characterisation of activated carbons surface propertiesPorous characteristics assessed by N2adsorption at 77K and acidic surface groups determined by the Boehm method are given in Table2.Both adsorbents have high speci®c surface areas.Whereas,CS-1501is mainly microporous(more than96%of micropores), RS-1301contains about32%of mesopores.These properties had been observed by scanning electron and atomic force microscopy in a previous study[26].The total number of surface sites and the speci®c surface area allow the surface site density to be calculated for each ACC.It is respectively equal to0.394sites nmÀ2 for CS-1501and0.330sites nmÀ2for RS-1301.Thesevalues are lower than those obtained for oxides(com-monly ranging from1to10sites nmÀ2[9,27])or¯y ash(121sites nmÀ2[28])due to the high speci®c surface areas of ACC compared with these adsorbents. They have the same order of magnitude than values obtained onto GAC,from0.05to0.3sites nmÀ2in [16]and about2sites nmÀ2[29].Data from acido-basic titrations were used to deter-mine the intrinsic surface acidity constants(p K a)of ACC with a®tting procedure using Fiteql software [20,13].Computations were made for only one value of ionic strength(I 0:1M)since a previous work on the same ACC showed the negligible in¯uence of salts concentration[30].Fig.1shows that experimental curves for samples CS-1501and RS-1301are in high agreement with modeled data.Calculated p K a values, added to the point of zero charge values(pH PZC)are also given in Table2.It should be noticed that PZC values con®rm the previous values obtained on the same materials using the so-called pH-drift method [18].The p K a and PZC for both ACC show the more alkalizing character of the RS-1301sample compared with the CS-1501.Table2Physico-chemical surface properties of ACCsCS-1501RS-1301 Porous characteristicsBET specific surface area(m2/g)16801460 Micropore volume(cm3gÀ1)0.6650.506 Micropores(vol.%)96.468.1 Acidic surface groups concentrations(meq.gÀ1)GI0.600.25 GII0.100.15 GIII0.400.40 GIV0.000.00 Total number of sites,N s(meq.gÀ1) 1.100.80 Acidic surface constantsp K a1 6.26 3.90 p K a29.3311.90 pH PZC7.509.53 Fig.1.Experimental and modeled titration curves for CS-1501and RS-1301.S 5g lÀ1,I 0:1M NaCl.C.Faur-Brasquet et al./Applied Surface Science196(2002)356±3653594.2.Batch mode adsorption of metal ions onto ACC Adsorption isotherms of the three metal ions onto the microporous ACC CS-1501are given in Fig.2.The same experiments were carried out with the mesoporous RS-1301.For the three metal ions,adsorption capacities on CS-1501are higher than those obtained with RS-1301,and this result may be related to the higher speci®c surface area,pore volume and surface groups content of the microporous CS-1501.All isotherms were modeled using models of Freundlich [31]and Brunauer±Emmett±Teller (BET)[32],parameters obtained being given in Table 3.The values of 1/n less than 1con®rm a favourable adsorption onto microporous adsorbents.For both adsorbents,the adsorption capacities q m order following:Cu 2 >Ni 2 >Pb 2 .The high ionicradius of Pb 2 (1.12AÊ)must induce a quick saturation of adsorption sites due to steric overcrowding com-pared with Cu 2 (0.70AÊ)or Ni 2 (0.69A Ê).The adsorption order may also be related to metal ions electronegativity,as reported by other studies [33,34].The reported effect is a stronger attraction for the higher electronegativity.To investigate the in¯uence of pH on adsorption,experiments were carried out for a pH ranging from 2to 10,and for both initial concentration values,20and 40mg l À1.To assess the part of precipitation in metal ions removal,the same measurements were carried out with and without ACC.Results obtained in the case of copper removal by both ACC are presented in Fig.3,the same kind of curves being obtained for nickel and lead.The pH adsorption or precipitation edges (pH units over which the fraction removed increasesfromFig.2.Adsorption isotherms of three metal ions onto the ACC CS-1501.C 0 0:1À1:4mmol l À1,V 250ml,ACC weight 500mg,T 208C,pH 5,stirring time 12h.Table 3Freundlich and BET parameters for metal ions adsorption onto ACC Metal ionACCBET parameters Freundlich parametersq m (mmol g À1)b (l mol À1)r 2K f (mmol 1À1/n l 1/n g À1)1/n r 2Cu(II)CS-15010.17446.50.9870.2010.2250.901RS-13010.13468.80.9990.1750.2280.846Pb(II)CS-15010.1470.810.9580.1250.5590.985RS-13010.1240.940.9670.1710.3310.972Ni(II)CS-15010.15215.40.9330.1870.3110.979RS-13010.12711.30.9860.0980.6550.961r 2:determination coef®cient.360 C.Faur-Brasquet et al./Applied Surface Science 196(2002)356±36510to 80%)are given for all metal ions and ACC in Table 4.In all cases,pH adsorption edges were very short,demonstrating the strong in¯uence of pH on adsorption.The following hypothesis may be made:1.Adsorption at pH 5occured for all metal ions below the pH of precipitation and was conse-quently the only mechanism of metal ion removal like in previous researches [15,16].For each metal ion,the pH range used for the DLM application was selected to be below the pH of precipitation.Associated to speciation diagrams (see Appen-dices),the inorganic species,other than free metalion M 2 ,present in solution were determined and taken into consideration in the model.The pH ranges and inorganic species considered for modeling are also included in Table 4.2.The increase in metal ion removal with pH may be explained by a decrease in electrostatic repulsion between cations and the positively charged surface of ACC at high pH values (pH PZC 7:50for CS-1501and 9.53for RS-1301).Maximum adsorp-tion,for copper and lead,occurs in a narrow pH range about 2±6or 3±4,respectively,where partial hydrolysis of cations results in the formation of hydrolyzed species (Table 4)which arelessFig.3.Effect of pH on copper removal by adsorption onto CS-1501and RS-1301/precipitation.C 0 20or 40mg l À1,V 250ml,ACC weight 500mg,T 208C,pH 2À10,stirring time 48h.Table 4Results of pH in¯uence on metal ions removal:pH adsorption and precipitation edges;pH ranges and inorganic species considered for modelingMetal ion Cu 2 Pb 2 Ni 2 CS-1501RS-1301CS-1501RS-1301CS-1501RS-1301pH adsorption edge 2.5±52±63±43±44±95±9pH range for modeling 2±72±62±8Species,p K aCu 2 0Pb 2 0Ni 2 0CuOH 6.3PbOH6.3NiOH4.1CU(OH)213.4Cu 2(OH)2217.7aEquilibrium constants from [25].C.Faur-Brasquet et al./Applied Surface Science 196(2002)356±365361charged and soluble than free metal cations Cu2 or Pb2 .In case of nickel adsorption,the maximum range was shifted to pH4±9because of the formation of Ni(OH) at these pH.The larger pH adsorption range may be related to a lower af®nity of this ion with activated carbon surface.The comparison of adsorption curves for initial metal ion concentrations of20and40mg lÀ1shows that the removal ef®ciency of metal ions(%)is affected by a concentration increase and that at20mg lÀ1,the curves are shifted to more acidic regions.This result, previously reported by several authors[16,29,35],may be explained by a saturation of higher energy adsorp-tion sites at high concentrations.4.3.Modeling of metal ions adsorption on ACC by the double layer modelIn the proposed SCM,below the pH of precipita-tion,all metal ions were supposed to be adsorbed by forming monodentate complexes with surface sites according to Eq.(4).The surface sites concentration and the acidity constants obtained respectively by the Boehm method coupled with N2adsorption data and the modeling of proton complexation were used without further adjustment and considered as®xed parameters.The ionic strength not being®xed during adsorption experiments,this parameter was calcu-lated simultaneously with the iterative computation of equilibrium constant by Fiteql[20].The Davies equation was used to calculate activity coef®cients for species in solution.Modeling results of the three metal ions adsorption onto CS-1501are given in Figs.4±7,and calculated values of equilibrium con-stants are presented in Table5(except for couples Cu2 ,20mg lÀ1/RS-1301and Pb2 /RS-1301where the iterative computation did not converged).As shown by Fig.4,the DLM can model the experimental data,especially for low concentrations. The modeling quality is lower for nickel than for both other metal ions,with the form of the curve(C0ÀC e) versus pH which does not reach a plateau like both others metals and lower values for complexation constants(Table5).This result may be due to the fact that hydrolysis of nickel cations is shifted to higher pH(>7,see speciation diagram in Appendices) than those of Cu2 (pH>5)or Pb2 (pH>6),and the af®nity between nickel and ACC is thus lower in this range of pH because of the pH PZC value of ACC(7.50 and9.53for CS-1501and RS-1301,respectively). Results provided in Table5allow to order adsorp-tion complexation constants following:Pb2 >Cu2 @Ni2 for metal ions and CS-1501>RS-1301for Fig.4.Modeling of adsorption of copper,lead and nickel onto CS-1501using the DLM.362 C.Faur-Brasquet et al./Applied Surface Science196(2002)356±365ACC.This order differ from that obtained with max-imum adsorption capacities (q m Cu II >q m Ni II >q m Pb II )in a batch reactor for several simultaneous reasons:(1)because adsorption isotherms were car-ried out at pH 5whereas all the pH values,from 2to 8(depending on the metal ion considered),are consid-ered for the modeling;(2)because adsorption versus pH was studied for the same initial concentration on a mass basis (C 0 20or 40mg l À1)but the high mole-cular weight of lead induces lower initial concentra-tions,on a molar basis,for this metal ion.ThismustFig.5.Speciation diagram of copper,C 30mg l À1.Fig.6.Speciation diagram of nickel,C 30mg l À1.Table 5Surface complexation constants obtained using the DLM Metal ion Initialconcentration (mg l À1)log K int BSOMCS-1501RS-1301Cu220 2.909n.a.40 2.1020.293Pb 2 20 4.137n.a.40 2.545n.a.Ni 2200.068À0.38240À0.021À0.606n.a.:not available.C.Faur-Brasquet et al./Applied Surface Science 196(2002)356±365363involve a faster saturation of adsorption sites for the more concentrated solutions,namely those containing copper and nickel ions;(3)because the hypothesis of a single reaction,see Eq.(4),was made for complexa-tion of all metal ions.However,in the case of copper,speciation diagram (Appendices)shows that the pre-sence of hydrolized species is signi®cant compared with both other metal cations.The adsorption of these hydrolized species being not taken into account by the DLM for the computation of the complexation con-stants,the copper complexation constant is less than that of lead whereas maximum adsorption capacities is higher.Values obtained for complexation constants are in the same order of magnitude than that of [16]in thecase of copper adsorption onto a GAC,K intB SOM $6.5.ConclusionThis study has shown the ability of ACC to remove metal ions from aqueous solutions.The in¯uence on maximum adsorption capacities of adsorbent porosity and adsorbate characteristics (electronegativity,ionic radius)was pointed out.All the experiments were carried out at pH 5,below the precipitation pH.When adsorption was studied as a function of pH,short adsorption edges showed a strong dependence of adsorption on pH solution because of the decrease of electrostatic interactions due to the formation of hydrolyzed species as this parameter was increasing.A second part has focused on the modeling of adsorption of metal ions onto ACC using a SCM,the DLM.Physico-chemical parameters relative to adsorbent,namely speci®c surface area,surface acid-ity constants and total number of surface cites,have been determined.The modeling quality was quite good,and allowed the surface complexation constants to be calculated.A future objective will be to use 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Nd^(3+)掺杂ZnO-MgO-Al_(2)O_(3)-SiO_(2)系微晶玻璃的制备及光学性能
第42卷第5期2021年10月Vol.42 No.5Oct. 2021Journal of C eramicsDOI: kLtcxb.2021.05.004Preparation and Optical Properties of Nd 3+-dopedZnO-MgO-Al 2O 3-SiO 2 Glass-ceramicsJIAO Zhiwei, HOU Zhengzheng, LIU Wei, ZHANG Tao, CAO Leigang, LI Sheng, GUO Yanxing(North China University of Technology, Beijing 100144, China)Abstract: Nd 3+ doped spinel phase glass-ceramics were obtained through heat-treatment of their parent glass prepared by usingmelt quenching method. The relationship between the heat treatment conditions and optical properties of the glass-ceramics was studied. Differential thermal analysis (DTA), X-ray diffraction (XRD), UV-visible spectrophotometer and fluorescencespectrometer were utilized to characterize crystallization behavior of the glasses and optical properties of the glass-ceramics. It is confirmed that MgAl 2O 4 and ZnAl 2O 4 were precipitated in the parent glasses after heat treatment. With increasing crystallizationtime, the degree of crystallization of the glasses is increased first and then decreased, while the average crystals size is increasedslowly. Ultraviolet-visible absorption and luminescence behaviors of the as-prepared glass-ceramics were studied, indicating thatNd 3+ entered the spinel lattice. Over 800-1400 nm, three emission peaks are present, due to the energy level transitions of Nd 3+.Luminous intensity of the glass-ceramics is increased as the degree of crystallization is increased. The sample after crystallizationfor 1.5 h shows the strongest fluorescence effect. At 1064 nm, the intensity of the emission peak is much higher than the other twoemission peaks, indicating that it is a potential near-infrared fluorescent material.Key words: glass-ceramics; spinel; Nd 3+; fluorescence1 IntroductionOptical functional materials are widely used in the fields of laser technology, lighting, optical communication, optical storage and so on. In order to achieve specific luminescent properties, specific activated ions, such as trivalent rare-earth ions, are commonly introduced into the matrix of optical materials Rare-earth ions doped spinel crystals have been paid great attention for their potential applications as temperature sensors and luminescent materials ® 6]. For a long time, efforts have been made in the preparation of high quality rare earth doped single spinel crystals. However, the strict growth environment, long cycle time and high cost make it very difficult to obtain such single crystals. Therefore, it is a meaningful work to explore new spinel materials.MO-A12O3-SiO2 (M=Zn, Mg) glass-ceramics containing Z11AI2O4 or MgAl 2O4 crystalline phase have been acknowledged to be potential optical functional materials, which have various advantages, such as high chemical durability, high thermal stability, high mechanical strength, simple preparation process, low cost and high transparency in the visible and near infrared ranges "切. Malyarevich et al. prepared Co 2+ doped MgAl 2O 4glass-ceramics, which can be used as a saturated absorber in a 1.54 jim Er glass Q-switched laser [10]. Duan et al. prepared a series of Co 2+-doped (MgGa2°4, Z11AI2O4 and MgAbOJ spinel glass-ceramics by using a sol-gel method, where the effects of composition and heat treatment temperature on microstructure of the glass-ceramics were studied [11]. They also evaluated absorption and saturation characteristics of Co 2+ and Co 2+ distribution in the glass-ceramics 卩'e t al. studied the luminescence properties of Ni 2+-doped ZnAl 2O 4 phase transparent glass-ceramics. It was found that near-IR emission with a full width at half maximum (FWHM) of approximately 300 nm at 1310 nm was generated, indicating the potential applications in optical fiber amplifiers and tunable lasers [14]. However, the luminescence properties of rare earth ion-doped spinel glass-ceramics have rarely been reported.Nd 3+-doped transparent glass ceramics are typically used in the fabrication of solid-state lasers, due to their high absorption coefficient, large emission cross-section, long fluorescence decay time, wide absorption bandwidth and high fluorescence branching rate [15, 16]. In the present work, ZnO-MgO-Al 2O 3-SiO2 (ZMAS) glass ceramics with Nd 3+ doped ZnAl 2O 4 and MgAl 2O4Received date: 2021-05—27. Revised date: 2021-07—02.Funding projects: General Project of Beijing Municipal Education Commission (KM201610009005).Correspondence authors: JIAO Zhiwei (1981-), Male, Ph.D., Professor.E-mail ^zwzv (*********.・750・2021年10月spinel solid solutions as the main crystal phases were prepared.The relationship between the heat treatment conditions and optical properties of the glass-ceramics were discussed,so as to offer a feasible way to develop new MAS optical glassceramics.2Experimental procedureComposition of the base glass is listed in Table 1.All the reagents were analytical grade.Fully ground raw mixture was melted at1600°C for3h. The molten glass was poured into a mold and parent glass samples were obtained after cooling.After the base glass was annealed at600°C in order to relieve internal stress,subsequent tests were performed.DTA measurement was performed using an integrated thermal analyzer(STA7300,Hitachi Ltd., Japan)to determine the phase transition temperature. Phase identification was carried out with a diffractometer(D8Advance,Bruker Co.,Germany) using Cu K a radiation in the20range of10~70°, with a step width of0.02°.Absorption spectra of the glass-ceramics were measured by using a UV-visible spectrophotometer(UV-1800,Shimadzu Co.,Japan). Luminescent spectra for the polished glass-ceramic samples were recorded at room temperature with a steady-state/transient fluorescence spectrometer (FLS980,Edinburgh Instruments Ltd.,England).The scan slit width is0.5nm in the measurements of emission and excitation spectra.All tests were performed at room temperature.3Results and DiscussionFig.1shows DTA curve of the as-prepared parent glass with a heating rate of10K-min_1.A plateau is observed near764°C,which corresponds to the glass transition temperature(T g)of the sample. The onset temperature(T x)and peak temperature (T c)of crystallization were measured to be985°C and1045°C,respectively.Heat-treatment experiment was then performed according to the DTA curve,with the glass samples being heated at780°C for6h and985°C for0.5h,1.0h,1.5h,and2.0h,followed by cooling down to room temperature in the electric furnace. Fig.2shows XRD patterns of Nd3+-doped ZAMS glass-ceramic samples before and after the heat-treatment.No identifiable diffraction peaks are present in the parent glass,indicating its amorphous characteristics.In contrast,the glass-ceramic samples after heat treatment displayed obvious diffraction peaks,indicating the precipitation of the crystallites from the amorphous matrix.The main crystallites in the glass-ceramic are MgAl2O4and Z11AI2O4,with secondary crystalline phases of Mg2TiO4and Zn2TiO4,which were formed initially as nucleus.Firstly,TiO2caused the glass to differentiate into phases to form Ti-rich and Si-rich regions.Then,TiC)2was discharged from the silicate network in the Si-rich region and combined with the divalent metal ions(such as Mg2+and Zn2+)to form titanate.The spinel phases nucleated and grew based on the titanate phase[17].With increasing crystallization time,the diffraction peaks were gradually sharpened and narrowed,indicating the increase in the crystallinity.The sample heat-treated for2h showed a third phase with unconfirmed structure,due probably to the participation of the spinel phase during melting process.Therefore,the highest crystallinity was achieved in the sample after heat treatment at985°C for1.5h,so that1.5h was the optimal crystallization time.Tab.1Composition of the ZMAS glass(wt.%)Component MgO ZnO AI2O3SiO2TiO2ZrO2Nd(NO3)3 Content 5.537.1922.1459.23 3.34 2.460.11Temperature/°CFig.1DTA curve of the Nd現doped ZMAS glass Fig.2XRD patterns of the Nd3+-doped ZAMSglass-ceramicsamples第42卷第5期焦志伟等：Nd?*掺杂ZnO-MgO-Al2O3-SiO2系微晶玻璃的制备及光学性能（英文）・751・The average crystals size can be calculated according to the full width at half maximum of the XRD diffraction peak of Mg/ZnAl2O4,with the Scherrefs formula:D=——(1) A(20)cos0where K is a constant(0.89),2is the X-ray wavelength,0is the diffraction angle and A(20)is the full width at half maximum of the diffraction peak.The applicable range of this formula is the crystals size of1〜100nm.The calculated sizes of the crystallites are shown in Fig. 3.The average size increases from9nm to13nm with increasing time at 985°C.12.512.011.511.010.510.09.50.5 1.0 1.5 2.0Crystallization time/hFig.3Average crystals size of the Nd3+-doped ZAMSglass-ceramic samples after crystallization for0.5〜2.0h.Fig.4shows absorption spectra of the as-prepared and heat-treated samples in the wavelength range of300〜800nm.The absorption band of Nd3+is observed,corresponding to the4f3 electron configuration of Nd3+from the ground state 4I q/2to the excited states of4Dn/2+^D3/2+2In/23 4G ii/2+2G9/2+2D3/2+2K15/2,2K i3/2+4G7/2+4G9/2, 4G5/2+2G7/232H11/2j4F9/2and4F7/2+4S3/2[18].There is no significant difference in the absorption curves of the glass-ceramics,which indicates that the structure of spinel was not changed after the heat treatment for different times.The difference in the absorption spectra of between the glass and glass-ceramic indicates that the ligand field of Nd3+was changed. The glass sample showed a wide absorption band, while the absorption band of the glass-ceramic had higher resolution,indicating that the spinel crystals precipitated during the heat treatment were doped with Nd3+at the A site[19,20].The inset in Fig.4 presents the transparency of the heat-treated samples at985°C for0.5〜2.0h,showing a decreasing trend in the transparency in the visible light region with increasing time.This is ascribed to the increased number and size of the nanocrystallites in the glass matrix,which acted as scattering sources[21].d TQuninum严=aA lOUght ashase and nhacA phase anGlass0.5h1.0h1.5h2.0h(・n d)uog&osqvfD5/2+2D3/2+2111/24g7/2G s/2|g?/21:Glass2:950°C,0.5h3:950°C,1.0h4:950°C,1.5h5:950°C,2.0h4F r4f7/2+4s3/24321 300350400450500550600650700750800Wavelength(nm)Fig.4Absorption spectra of the Nd3+-doped ZAMS glass-ceramic samples.The inset shows the sample photos of glass and glass-ceramics obtained after differentheat treatment timesFig.5shows emission spectra of the glassceramic excited at488nm at room temperature and the inset shows an energy-level diagram of Nd3+. There are three distinct emission peaks at905nm, 1064nm and1350nm,which could be attributed to the transition of Nd3+from4F3/2to4Ij(J=9/2,11/2, and13/2).The fluorescence intensity of the glassceramic samples was enhanced,as compared with that of the matrix glass.With increasing crystallization time,the intensity of the emission peaks gradually increased.In crystalline state,the efficiency of energy transfer between the neodymium ions is higher,thus leading to increased luminescence intensity.The sample heat-treated at 985°C for1.5h displayed the maximum emission intensity at1064nm.However,over heating would weaken the fluorescent strength.On one hand,too long heat-treating time would lead to the increase in the content of the crystalline phase,so that the scattering loss is increased and hence the excitation and emission are weakened.On the other hand,the more Nd3+ions enter the spinel phase,the shorter the distance between the ions shortens and the higher the energy transfer would be,thus leading to the presence of concentration quenching phenomenon and hence decreased emission intensity.Among all the emission peaks,the intensity of the emission band near1064nm corresponds to the 4F3/2^4F ii/2transition,which is higher than those of the other two transitions.This demonstrates that the sample is a potential near-infrared fluorescent material.[22].・752・2021年10月1: Glass2卑22: 985 °C, 0.5 h 4F 3/2^4I 11/2\ Noii-radiative decay3:985 °C, 1.0 h 4: 985 °C, 1.5 h 5:985 °C, 2.0 humo虽u m寸92§S O 6U I U 88寸(・n ・E )b i s u e u i80090010001100 1200 1300 1400 1500 1600Wavelength (nm)Fig. 5 Luminescence spectra of the Nd 現doped ZMAS glass-ceramic samples under 488 nm excitation (Theinset shows an energy-level diagram of Nd 3+)4 ConclusionsNd 3+-doped ZnO-MgO-Al 2O 3-SiO 2 (ZMAS) transparent glass-ceramics were obtained. The crystalline phases are mainly MgAl 2O4 and ZnAl 2O4. With the extension of time, the degree of crystallization first increased and then decreased. The luminescence intensity of neodymium ions was closely related to the degree of crystallization. Compared with the parent glass, the glass-ceramic sample displayed significantly enhanced luminescence intensity. The absorption spectra of the glass-ceramic indicated that Nd 3+ entered the spinel lattice. The fluorescence emission intensity of glass-ceramics increased first with increasing heat treatment time and then decreased, which was attributed to the increase in crystallinity of the samples. The results of fluorescence spectrum indicated that the Nd 3+-doped spinel phase glass-ceramics have potential applications as near-infrared fluorescent materials.参考文献：[1]KITAJIMA S, YAMAKADO K, SHIRAKAWA A, et al.Yb 3+-doped CaF 2-LaF 3 ceramics laser [J]. Optics Letters,2017, 42(9): 1724-1727.[2]YE S, XIAO F, PAN Y X, et al. 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Journal of第42卷第5期焦志伟等：Nd”掺杂ZnO-MgO-Al2O3-SiO2系微晶玻璃的制备及光学性能（英文）•753•Inorganic Materials,2002,17(1):45-50.[18]CARNALL W T,FIELDS P R,RAJNAK K.Electronicenergy levels in the trivalent lanthanide aquo ions.I.Pr3*, Nd3+,Pm3+,Sm3+,Dy3+,Ho”,Er3：and Tm3+[J],TheJournal of Chemical Physics,1968,49(10):4447-4449. [19]BOULESTEIX R,MAITRE A,LEMANSKI K,et al.Structural and spectroscopic properties of MgAl2O4:Nd3+transparent ceramics fabricated by using two-step sparkplasma sintering卩].Journal of Alloys and Compounds,2017,722:358-364.[20]derei Q p j,maleszka-bagd Q ska k,GLUCHOWSKI P,et al.Spectroscopic properties of Nd3+in MgAl2O4spinel nanocrystals[J].Journal of Alloys and Compounds,2012,525:39-43.[21]MOLLA A R,TARAFDER A,MUKHERJEE S,et al.Transparent Nd3+-doped bismuth titanate glass-ceramicnanocomposites:Fabrication and properties[J].OpticalMaterials Express,2014,4(4):843-863.[22]CHEN D,WANG Y,YU Y,et al.Fluorescence andJudd-Ofelt analysis of Nd3+ions in oxyfluoride glassceramics contaming CaF2nanocrystals[J].Journal of Physics and Chemistry of Solids,2007,68(2):193-200.N（f+掺杂ZnO-MgO-Al2O3-SiO2系微晶玻璃的制备及光学性能焦志伟，侯铮铮，刘伟，张涛，曹雷刚，栗晟，郭延兴（北方工业大学，北京100144）摘要:采用高温熔融法和热处理制备了Nd”掺杂的尖晶石相的ZnO-MgO-Al2O3-SiO2系透明微晶玻璃，研究了微晶玻璃热处理条件与光学性能之间的联系。