共查询到20条相似文献,搜索用时 610 毫秒
1.
PVT法生长SiC单晶生长腔的温场分布是影响晶体质量的重要因素.采用数值模拟研究了保温层和坩埚结构以及线圈位置对6英寸SiC晶体生长温场的影响,优化出了适合高品质6英寸SiC晶体生长温场分布,在此条件下生长无裂纹的6英寸N型4H-SiC晶体.用高分辨率X射线衍射、拉曼光谱和缺陷检测系统对所加工的SiC衬底片的质量进行了表征.测试结果表明,晶型为单一的4H-SiC,微管密度小于1 cm-2,电阻率范围为0.02~0.022Ω·cm,X射线摇摆曲线半高宽为21.6″. 相似文献
2.
坩埚旋转下降法生长硒镓银单晶体 总被引:1,自引:1,他引:0
本文报道了硒镓银多晶原料合成与单晶生长的新方法--熔体温度振荡法和坩埚旋转下降法.5~6N高纯Ag、Ga、Se单质按AgGaSe2化学配比富0.5;Se配料,1100℃下合成并在熔点附近进行温度振荡,获得了高纯单相致密的AgGaSe2多晶材料.用合成的多晶为原料,采用坩埚旋转下降法生长出φ22×80mm的AgGaSe2单晶锭.晶体外观完整,在10.6μm附近红外透过率达62.4;,吸收系数低于0.01cm-1,对10.6μm CO2激光实现倍频,能量转换效率达12;. 相似文献
3.
4.
采用高压釜法合成了单相、致密的LiInS2多晶原料,采用改进的Bridgman晶体生长技术进行红外非线性光学晶体LiInS2的生长研究,获得了12 mm×40 mm的高质量完整单晶.对所获得的LiInS2晶体进行了组分分析、高分辨X射线衍射、激光损伤阈值等测试表征,测试结果表明:晶体存在硫过量和锂不足(NLi: N In<1),各组分稍微偏离化学计量比;LiInS2晶体的 (040)面的半峰宽为78.84',表明晶体具有较好的完整性;晶体的激光损伤阈值为109 MW/cm2,有待于通过提高晶体质量和晶体表面的质量来进一步提高. 相似文献
5.
6.
采用共蒸发的方法在玻璃衬底上制备出GaSb多晶薄膜材料.研究了薄膜生长速率与衬底温度、Ga源温度和Sb源温度的关系.通过XRD、UV-Vis、Hall效应和AFM等测试方法,研究了衬底温度对于GaSb薄膜的结构特性、光电性质以及表面形貌的影响.GaSb多晶薄膜具有(111)择优取向,薄膜的吸收系数达到105 cm-1,晶粒尺寸随衬底温度升高逐渐增大;衬底温度为540℃时,薄膜的迁移率达到127 cm2/V·s,空穴浓度为3×1017 cm-3.GaSb薄膜的表面粗糙度随温度增加而增加. 相似文献
7.
GaAs单晶作为一种重要的LED衬底材料在光电器件中应用十分广泛,但载流子浓度(C.C.)分布不均、杂质浓度过高等缺陷会严重影响相关器件的性能.为制备纵向载流子浓度分布均匀的掺硅HB-GaAs单晶,本文探讨了单晶生长过程中熔区长度对纵向载流子浓度分布的影响.以高纯GaAs多晶为原料,设定不同的拉晶温度曲线,采用窄熔区技术进行晶体生长研究,最终生长出C.C.值分布更均匀、位错密度低(EPD≤10 000 cm-2)的<111>向N型掺硅GaAs单晶.利用辉光放电质谱法(GDMS)和范德堡法霍尔效应测试对晶体进行了表征,单晶纯度达到5N且无硼杂质沾污. 相似文献
8.
两温区气相输运和机械振荡合成ZnGeP2多晶材料 总被引:3,自引:2,他引:1
ZnGeP2多晶的合成是其单晶生长的前提和基础,多晶材料的质量是生长高质量单晶的关键.因此,要获得高质量的ZnGeP2单晶体,必须提供高质量的ZnGeP2多晶材料.对两温区气相输运机械振荡法合成ZnGeP2多晶材料的工艺进行了研究,利用高纯(6N)P、Ge、Zn单质为原料,采用两温区气相输运和机械振荡合成出了ZnGeP2多晶材料.合成出的多晶材料经比重测试和X射线粉末衍射测试证明与标准值一致.采用改进的布里奇曼法生长出外观完整、无裂纹的φ15 mm × 25 mm单晶体,在2.5~10 μm范围内红外透过率达50;以上. 相似文献
9.
采用高压垂直温度梯度凝固法(VGF)生长了非掺、掺硫和掺铁的4 inch直径(100)InP单晶,获得的单晶的平均位错密度均小于5000 cm-2.对4 inch InP晶片上进行多点X-射线双晶衍射测试, 其(004)X-射线双晶衍射峰的半峰宽约为30弧秒且分布均匀.与液封直拉法(LEC)相比, VGF-InP单晶生长过程的温度梯度很低,导致其孪晶出现的几率显著增加.然而大量晶体生长结果表明VGF-InP晶锭上出现孪晶后,通常晶体的生长方向仍为(100)方向,这确保从生长的4 inchVGF-InP(100)晶锭上仍能获得相当数量的2~4 inch(100)晶片.由于铁在InP中的分凝系数很小,掺Fe-InP单晶VGF生长过程中容易出现组份过冷,导致多晶生长.通过控制生长温度梯度及掺铁量,可获得较高的掺铁InP单晶成晶率.对VGF-InP单晶的电学性质、位错密度及位错的分布特点、晶体完整性等进行了研究. 相似文献
10.
11.
A. L. Bingham J. E. Drake C. Gurnani M. B. Hursthouse M. E. Light M. Nirwan R. Ratnani 《Journal of chemical crystallography》2006,36(10):627-630
Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P2S5 in toluene and have been characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et3NH]+[(4-MeC6H4O)2PS2]−: Monoclinic, P21/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?−3, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et3NH]+[(4-MeC6H4O)2PS2]− comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk). 相似文献
12.
Lin Zhu Karl Seff Thomas Witzke Lutz Nasdala 《Journal of chemical crystallography》1997,27(5):325-329
The structure of Zn4Na(OH)6SO4Cl·6H2O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and Rw=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na+ ions which occupy the interlayer space. 相似文献
13.
Jerry P. Jasinski Ray J. Butcher Anil N. Mayekar H. S. Yathirajan B. Narayana B. K. Sarojini 《Journal of chemical crystallography》2009,39(10):761-765
Abstract The title compound, C18H18BrN3O3S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol
ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine
ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely
packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional
series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene
group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the
crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal]
reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving
support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these
angles which therefore play a role in stabilizing crystal packing.
Graphical Abstract Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C18H18BrN3O3S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Zun-Ting Zhang Xue-Ling Zhang Bo-Lun Yang Yao-Dong Zhang 《Journal of chemical crystallography》2006,36(7):407-411
Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P21/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure. 相似文献
15.
Maurizio Remelli Fernando Pulidori Remo Guerrini Valerio Bertolasi 《Journal of chemical crystallography》1997,27(9):507-513
The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, Nπ-hydroxymethyl-spinacine, and a spinacine derivative, Nα-methyl-spinaceamine, have been investigated through X-ray diffraction: Spi(πMeOH)·H2O, monoclinicP2 i,a=8.571(1),b=6.682(1),c=8.588(1) Å, and β=94.67(1)o. Spm(αMe)·2HCl·H2O, triclinicP l,a=7.492(4),b=10.799(3),c=7.040(2) Å, α=91.88(2), β=98.36(3) and γ=73.34(3)o. Spi(πMeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) Å between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O?H???O, O?H???N, N?H???N intermolecular hydrogen bonds and C?H???O close contacts. The biprotonated compounds Spm(αMe) crystallizes with two Cl? anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C?N. The crystal is built up by clusters formed by two biprotonated Spm(αMe) molecules, four Cl? anions and two water molecules linked together by hydrogen bonds. 相似文献
16.
Maurizio Remelli Fernando Pulidori Remo Guerrini Valerio Bertolasi 《Journal of chemical crystallography》1991,27(9):507-513
The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product
with an excellent yield. The crystal structures of a synthetic intermediate, Nπ-hydroxymethyl-spinacine, and a spinacine derivative, Nα-methyl-spinaceamine, have been investigated through X-ray diffraction: Spi(πMeOH)·H2O, monoclinicP2
i,a=8.571(1),b=6.682(1),c=8.588(1) ?, and β=94.67(1)o. Spm(αMe)·2HCl·H2O, triclinicP
l,a=7.492(4),b=10.799(3),c=7.040(2) ?, α=91.88(2), β=98.36(3) and γ=73.34(3)o. Spi(πMeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial
position and forms a short electrostatic interaction of 2.618(2) ? between one of its oxygens and the protonated nitrogen
of the tetrahydropyridine ring. The crystal packing is assured by strong O−H−−−O, O−H−−−N, N−H−−−N intermolecular hydrogen
bonds and C−H−−−O close contacts. The biprotonated compounds Spm(αMe) crystallizes with two Cl− anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C−N. The
crystal is built up by clusters formed by two biprotonated Spm(αMe) molecules, four Cl− anions and two water molecules linked together by hydrogen bonds. 相似文献
17.
Samuel B. Owens Jr. Abha A. Kaisare Gary M. Gray 《Journal of chemical crystallography》2007,37(10):655-661
Abstract X-ray crystal structures of [Et3NH][{(CO)5Mo(P(OCH2CMe2CH2O)O)}2H], 3, and (CO)5Mo{μ-Ph2POPPh2}Mo(CO)5, 2, are reported. Crystallization of 3 occurs in P-1 space group with a = 9.6944(19) ?, b = 10.814(2) ?, c = 19.730(4) ?, α = 94.24(3)°, β = 92.23(3)°, γ = 113.47(3)°,
Z = 4. Crystallization of 2 occurs in C2/c space group with a = 10.357(2) ?, b = 20.149(4) ?, c = 17.155(3) ?, α = 90°, β = 97.28(3)°, γ = 90°, Z = 8.
Compound 2 is a bimetallic complex with a P–O–P bridging group containing bond distances similar to that of other complexes in which
two metal centers are bridged by a single R2POPR2 ligand. Compound 3 contains intermolecular hydrogen bonded P–O–H–O–P linkages with bond distances comparable to those seen in similar structures
with intramolecular hydrogen bonding suggesting that the distance is a function of the nature of the bond and not affected
by the cis arrangement of the ligands about the metal center.
Graphical abstract
X-ray Crystal Structures of [Et
3
NH][{(CO)
5
Mo(P(OCH
2
CMe
2
CH
2
O)
O)}
2
H]
and (CO)
5
Mo{μ-Ph
2
POPPh
2
}Mo(CO)
5
, Two Complexes Derived from the Hydrolysis of Coordinated Chloro-Phosphorous-Donor Ligands
Samuel B. Owens Jr., Abha A. Kaisare and Gary M. Gray
X-ray crystal structures of [Et3NH][{(CO)5Mo(P(OCH2CMe2CH2O)O)}2H], 3, and
(CO)5Mo{μ-Ph2POPPh2}Mo(CO)5, 2, have been determined.
相似文献
18.
G. C. Das M. B. Hursthouse K. M. A. Malik M. M. Rahman M. T. Rahman T. Olsson 《Journal of chemical crystallography》1994,24(8):511-515
1,3,5-triphenyl-1,5-pentanedione, C23H20O2, has been prepared and characterized by spectroscopic methods and single crystal X-ray analysis. Crystals are monoclinic, space groupP21/n, a=28.124(4),b=5.997(1),c=10.434(1)Å, -98.42(1)Å,Z=4. The structure has been refined to a finalR-value of 0.040 for 1625 reflections withF
o>3(F
o). The compound contains the two carbonyl groups in a mutuallycis arrangement. 相似文献
19.
Andrzej Chmielewski W. Alexander Van Hook 《Molecular Crystals and Liquid Crystals》2013,570(1-2):27-36
The phase diagrams and heats of fusion and transition have been determined for the dodecyl amine (-NH2)/H2O and dodecyl amine (-ND2)/D2O systems using direct optical observation and differential scanning calorimetry. 相似文献
20.
P. M. Reshmi A. G. Kunjomana K. A. Chandrasekharan 《Crystal Research and Technology》2011,46(2):153-158
Different morphologies of indium telluride (In2Te3) including novel spherulites were crystallized using the physical vapour deposition (PVD) method, by varying the difference in the growth and source zone temperature (ΔT) of a dual zone horizontal furnace assembled indigenously. Whiskers and kinked needles of In2Te3were grown at ΔT = 250 K and 300 K respectively, maintaining the growth zone at 500 °C. At high supersaturation (Δ T = 400 K), spherulitic crystals were obtained. The stoichiometric composition of these crystals has been confirmed using energy dispersive analysis by x‐rays (EDAX). The structure of β‐In2Te3 spherulitic crystals is identified as zinc blende with lattice parameter a = 6.159 Å, from x‐ray diffraction (XRD) studies. The scanning electron microscope (SEM) images revealed the radial structure of the grown spherulites. The growth mechanism for the spherulitic crystallization of β‐In2Te3 crystals has been discussed based on the theoretical models. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献