GaAs-GaN键合界面热应力的电子背散射衍射研究

采用扫描电镜(SEM)和电子背散射衍射(EBSD)技术,观察和分析了GaAs和GaN晶片热压键合的界面热应力和晶片键合质量.利用EBSD测量了GaAs-GaN键合界面的菊池花样质量、晶格转动、晶格错配和位错密度等应力敏感参数.结果表明,晶片键合质量良好,键合界面中心区域的热应力小于边缘区域的热应力.GaN层和GaAs层中的应力影响范围,在中心区域分别约为100 nm和300 nm,在边缘区域分别约为100 nm和500nm.EBSD显示的应力分布图与模拟应力场相似.模拟和计算表明,最大剥离应力和剪切应力分布在键合界面的边缘.剥离应力是导致晶片解键合的主要原因.     

热键合YAG/Nd:YAG复合晶体的透过光谱研究

本文在一定的温度和压力下,通过热键合技术,获得了YAG/Nd:YAG复合晶体.这种复合晶体在非吸收波段的光学透过率与通过一块相同厚度Nd:YAG晶体的光学透过率实验值以及理论值相一致.因此从透过率的角度,表明纯YAG晶体与Nd:YAG晶体间的键合区域为均匀过渡,基本上无散射界面存在,实现了一体化.     

柔性砷化镓薄膜太阳电池剥离(lift-off)技术研究

对柔性砷化镓薄膜太阳电池关键技术进行研究,通过对柔性衬底表面处理、外延片/柔性衬底键合、衬底剥离技术和柔性薄膜外延层器件工艺技术等进行研究,成功地将砷化镓电池外延层转移到柔性聚酰亚胺薄膜衬底上,研制出效率为30.5;(AM0,25℃)的柔性砷化镓薄膜太阳电池,其重量比功率达到2153 W/kg,为将来卫星及临近空间飞行器的应用打下技术基础.     

Nd:YAG/Cr4+:YAG键合棒的制作与激光性能

采用直接键合的方法将Nd:YAG激光棒与Cr4+:YAG调Q元件结合在一起,对Nd:YAG棒和Cr4+:YAG在键合前后的激光性能进行了实验比较.结果表明,键合技术能够有效地提高输出能量,压窄脉宽.     

不同原子堆垛的WC(0001)/TiN(111)涂层界面的结合强度建模与分析

WC(0001)与TiN(111)涂层界面的结合强度取决于其界面性质.本文采用第一性原理讨论WC(0001)与TiN(111)界面的结合能、界面能、电子结构和成键情况.结果表明:(1)在所有考虑的终端界面之中,结合能从大到小依次为C-HCP-Ti界面(9.19 J/m2)、W-OT-Ti界面(4.28 J/m2)、W-OT-N界面(2.98 J/m2).(2)C-HCP-Ti界面存在强共价键,两者结合强度最强.W-OT-Ti界面存在共价键和部分金属键,结合强度次于C-HCP-Ti界面结合强度.对于W-OT-N,其界面结合强度为弱共价键,结合强度相对较弱.(3)在整个ΔμC范围内W-OT-Ti、W-OT-N和C-HCP-Ti三种界面的界面能为负,说明这三种界面具有超高稳定性.     

复合结构激光陶瓷研究进展

多晶激光陶瓷相比单晶激光材料而言,具有可实现大尺寸制备的优势,并可通过结构和功能复合为固体激光器的设计提供最大的可能性和灵活性.复合结构激光陶瓷的制备方法除了采用传统的单晶键合工艺之外,还可以结合陶瓷近净尺寸成型和烧结过程的特点,从而极大地丰富了复合结构激光增益介质的可实现形式.本文综述了复合结构激光陶瓷的典型制备方法,并论述了几类复合结构激光陶瓷的应用与进展,并对复合结构激光陶瓷发展中的问题和发展方向进行了论述.     

氟化钇锂激光晶体生长与键合技术研究

采用密闭反应气氛电阻加热熔体提拉法与上称重自动控径技术生长稀土离子掺杂氟化钇锂系列(Re:YLF)激光晶体,通过优化热场设计,有效地解决了大尺寸YLF系列激光晶体生长过程中的开裂和直径控制起伏的问题,成功生长出了直径大于50 mm的YLF系列激光晶体,晶坯无晶界、基本无散射,光学均匀性良好.同时开展了YLF系列激光晶体热扩散键合技术研究,通过定向切割、轴向匹配和面形匹配光胶、构造高温度均匀性热键合温场,成功制备出了YLF键合激光晶体.     

Nd:YVO4/YVO4晶体的热键合及其激光性质的研究

为改善高功率激光器激光工作物质的热效应,本文采用热键合的方法研制了Nd:YVO4/YVO4复合晶体,键合晶体的波前干涉P-V值为0.082λ(λ=0.6328μm),键合面对波前的影响很小.它在LD端面连续泵浦条件下,从泵浦光到基频光的转换效率可达60;, 特别当泵浦功率比较大时,键合晶体的输出功率比单块晶体有较大的提高.     

生长气氛和速度在金红石(TiO2)单晶体生长中的作用研究

本文研究了生长气氛和生长速度在焰熔法金红石单晶体生长中的作用,对比了晶体在空气中与在氧气中退火的结果,测定了晶体试样的摇摆曲线和透过率.研究表明:金红石单晶体的生长受炉膛气氛、生长界面温度和生长速度的影响;炉膛气氛决定晶体能否形成,是关键因素;炉膛气氛中的氧分压大于液固界面(即生长界面)处熔体的氧离解压是生长完整晶体的前提条件;晶体在退火过程中消除热应力,但更重要的是通过氧化反应消除氧空位,在氧气氛中退火,可明显缩短退火时间.在所优化的实验条件下制备的晶体,完整性较好,透过率为70～72;,与商用晶体的透过率基本一致.     

SiC中间层对金刚石涂层硬质合金刀具膜 基界面结合性能的影响

基于第一性原理分别计算了WC-Co/Graphite/Diamond、WC-Co/SiCC-Si/Diamond和WC-Co/SiCSi-C/Diamond界面模型的粘附功、断裂韧性,分析了电子结构和态密度.结果表明:Graphite/Diamond界面粘附功极小,金刚石在石墨基面上成核不良;WC-Co/Graphite界面处Co与C(Graphite)原子具有同种电荷而相斥,添加SiC中间层改变了界面处原子的电荷分配与成键方式,WC-Co/SiC界面Co与C(或Si)原子具有异种电荷而相吸,且Co-Si(SiC)键强于Co-C(SiC)键;SiC/Diamond界面C(SiC)-C(Diamond)键强于Si(SiC)-C(Diamond)键.因此,三种界面模型中各界面的粘附功SiCSi-C/Diamond>SiCC-Si/Diamond>WC-Co/SiCSi-C>WC-Co/SiCC-Si>WC-Co/Graphite>Graphite/Diamond.总之,添加SiC中间层提高了金刚石涂层硬质合金刀具膜基界面结合性能.     

Crystal and Molecular Structure of the 1:2 Salt Formed Between 1,2-(4-Pyridyl)Ethane and 2-(4-Hydroxyphenylazo)Benzoic Acid

Abstract  Proton transfer occurred during co-crystallization of 1,2-(4-pyridyl)ethane with 2-(4-hydroxyphenylazo)benzoic acid to yield a salt comprising a 1:2 ratio of 1,2-bis(4-pyridinium)ethane dications and 2-(4-hydroxyphenylazo)benzoate anions. Centrosymmetrically related anions associate by charge-assisted O–H···O hydrogen bonds to form 24-membered {···OC₃N₂C₄OH}₂ synthons. These are connected into a supramolecular polymer via charge-assisted N–H···O hydrogen bonds involving the 1,2-bis(4-pyridinium)ethane dications. The compound crystallizes in the triclinic space group P−1 with a = 8.517(4) ?, b = 9.110(5) ?, c = 10.477(5) ?, α = 96.850(13)°, β = 94.446(12)°, γ = 104.946(10)° and Z = 1 {two anions and a dication}. Index Abstract  Supramolecular chains mediated by charge-assisted O–H···O and N–H···O hydrogen bonding are found in the salt containing a 1:2 ratio of 1,2-bis(4-pyridinium)ethane dications and 2-(4-hydroxyphenylazo)benzoate anions.      

Crystal and Molecular Structure of Dichloro(ethylenediamine)gold(III) Nitrate: [Au(NH<Subscript>2</Subscript>CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>NH<Subscript>2</Subscript>)Cl<Subscript>2</Subscript>]NO<Subscript>3</Subscript>

Abstract  The gold(III) atom in [Au(NH₂CH₂CH₂NH₂)Cl₂]NO₃ is chelated by the ethylenediamine (en) ligand and the approximately square planar geometry is completed by two chloride atoms. Weak Au···O and Au···Cl contacts are noted above and below the square plane leading to a tetragonally distorted octahedron for the gold(III) center. Extensive charge-assisted hydrogen bonding of the type N–H···O leads to the formation of a 2-D array and layers are consolidated into a 3-D network via C–H···O and C–H···Cl contacts. The compound crystallizes in the orthorhombic space group Pbca with a = 10.3380(11) ?, b = 8.2105(7) ?, c = 19.625(2) ?, and Z = 8. Index Abstract  Square planar complex cations form additional Au···O and Au···Cl interactions to form a tetragonally distorted octahedron for gold. The ionic components are connected into a 2-D array via charge-assisted N–H···O hydrogen bonding interactions.      

Two diastereomers of 2-[[β-(N-phenylamino)-α-methylphenethyl]-methylamino]-N,N-dimethylacetamide

The structures of two diastereomers ((1R,2R) and (1R,2S)) of the title compound have been determined. The molecular conformation of the (1R,2R) isomer is heavily influenced by strong intramolecular hydrogen bonding between the secondary and tertiary amine groups (N(1)…N(2) 2.629(8) Å; N(4)…N(5) 2.628(8) Å). In the (1R,2S) isomer no intramolecular interaction is observed, but somewhat weaker intermolecular hydrogen bonding does occur between the secondary amine and the carbonyl group of a neighboring molecule (N(1)…O(1) 2.960(6) Å) related by a 2₁ screw operation along thea-axis (x1/40). No close intermolecular contacts are observed for the (1R,2R) isomer. Crystal data for (1R,2R); monoclinic,P2₁ (No. 4),a=18.588(5),b=16.743(4),c=6.062(1) Å, β=97.26(2)^o,V=1871.5(8) A³, Z=4,D _cale=1.16 g/cm³. Crystal data for (1R,2S): orthorhombic,P2₁2₁2₁ (No. 19),a=8.008(2),b=9.985(3),c=23.458(5)Å,V=1875.8(6) ų, Z=4,D _cale=1.15 g/cm³.     

Investigations of dehydroepiandrosterone. Part I: crystal structure of sublimed DHEA

The crystal structure of an orthorhombic polymorph of the title compound, crystallized by sublimation, has been determined. Dehydroepiandrosterone, C₁₉H₂₈O₂, space groupP2₁2₁2₁ witha=6.6408(4)b=11.4423(11)c=22.085(2)Å,V=1678.2(4)ų,Z=4. The structure was refined toR=0.051 for 2645 observed reflections. The conformation of the molecule is similar to that found in other polymorphs and solvates, with a chair A ring, an 8, 9 half-chair B ring, a chair C ring, and a 14 envelope D ring. Molecules are linked in chains by OH...O hydrogen bonds involving the carbonyl oxygen atom. The O...O distance is 2.855(3) Å, and the angle about H is 171(2)^o.     

Liquid Crystals arrive back home at their birthplace

The preparation and characterisation of a series of hydrogen bonded liquid crystalline dimers containing benzoic acid, alkanoic acid and phenol donors and alkoxy-stilbazole or alkoxy-4-pyridone hydrogen bond acceptors are reported. These heterodimers possess strong intermolecular donor–acceptor hydrogen bonding. The heterodimers, as well some of the individual components used in their preparation, possess liquid crystalline phases.     

Structural studies of N-2-(3-picolyl)- and N-2-(4-picolyl)-N′-tolylthioureas

Reactions of 2-aminopicolines with 2- and 4-tolyl isothiocyanates yielded N-2-(4-picolyl)-N-4-tolylthiourea, 1, N-2-(3-picolyl)-N-4-tolylthiourea, 2, and N-2-(4-picolyl)-N-2-tolylthiourea, 3. Compound 1 is monoclinic, of space group P2₁/c with a = 7.456(1) Å, b = 13.135(3) Å, c = 13.959(3) Å, = 104.99(3)°, and V = 1320.5(5) ų with Z = 4, for d _calc = 1.294 g/cm³. Compound 2 is triclinic, of space group with a = 6.877(3) Å, b = 7.590(5) Å, c = 13.213(9) Å, = 78.38(2)°, = 77.96(4)°, = 86.36(4)°, and V = 660.5(7) ų with Z = 2, for d _calc = 1.294 g/cm³. Compound 3 is monoclinic, of space group P2₁/c with a = 12.604(2) Å, b = 15.592(3) Å, c = 6.875(2) Å, = 91.05(2)°, and V = 1350.9(2) ų with Z = 4, for d _calc = 1.265 g/cm³. The three thioureas are found in both solid state and solution in a conformation resulting from intramolecular hydrogen bonding. Compounds 1 and 3 present an intermolecular hydrogen bond involving the thione sulfur and the NH hydrogen, which is not present in 2 owing to the steric hindrance of the methyl group in the phenyl ring. The geometry of the molecule is affected by the position of the methyl groups on the pyridine and aryl rings.     

Silver(I) complexes of 6-methyl-2-pyridinecarboxylic acid: the crystal structure of [Ag(MeC5H3NCOO)(MeC5H3NCOOH)]

Silver(I) complexes of 6-methyl-2-pyridinecarboxylic acid (HL) have been prepared, and the crystal structure of [Ag(L)(LH)] has been determined from X-ray diffraction data. This complex crystallizes in the monoclinic space group P2₁/n, with a = 13.4055(13), b = 7.1012(7), c = 15.588(2) Å, = 112.779(2)°, and Z = 4. Anionic [AgL₂]^– units are linked together by protons in approximately symmetrical linear O—H—O hydrogen bonds involving uncoordinated carboxylate oxygen atoms, to give polymeric chains. The most significant intermolecular interaction between adjacent parallel chains is offset ring stacking of pairs of aromatic rings with a perpendicular distance of 3.27 Å. The Ag coordination geometry is highly distorted tetrahedral, from two pyridine N atoms and two carboxylate O atoms, each ligand forming a five-membered chelate ring.     

Crystallographic investigations of benzothiazol-2-yl-hydrazine

The title compound crystallizes in the monoclinic space group P2₁/n with unit cell parameters a = 10.842(9), b = 5.750(7), c = 12.964(6) Å, = 110.13(6), V = 758.8(11) ų and Z = 4. The final reliability index is 0.060 for 1034 observed reflections. The five-membered heterocyclic thiazole ring is coplanar with its fused benzene ring. The crystal structure is stabilized by two intermolecular N=H s N hydrogen bonded interactions.     

α-Iminohydroxylamine-α-aminonitrone tautomerism: a 1∶1 mixture of two tautomeric forms in crystals of N-(4,5-dihydro-1H-imidazol-2-yl)-N-phenyl-hydroxylamine

Crystals consisting of two distinct chemical entities, tautomers of each other, in exact 11 ratio, have been obtained and their structure determined by X-ray analysis. The crystals of C₉H₁₁N₃·C₉H₁₁N₃ are monoclinic,P2₁/c,a=15.674(3),b=17.085(3),c=13.758(3)Å, =90.78(2)°,Z=8. There are two hydroxylamine and two aminonitrone molecules in the asymmetric unit. Hydrogen bonds connect those molecules into chiral layers. Layers of opposite chirality alternate andthe crystal is centrosymmetric as a whole. Within those layers chains of tautomers joined by very strong O–H... O and strong N–H... N bonds can be recognized. Proton transfer along those chains with simultaneous rearrangement of -bonds within the molecules would result in interconversion of tautomers and would affect chirality of the layer.