闪烁单晶钨酸锌的坩埚下降法生长

通过高温固相反应或湿化学法合成ZnWO4多晶料,采用垂直坩埚下降法生长出φ25 mm× 60 mm的透明完整钨酸锌单晶.应用X射线粉末衍射分析证实了所制备钨酸锌多晶与单晶的结晶物相,测试了钨酸锌单晶的紫外可见透射光谱、光致发射光谱和X射线激发发射光谱,讨论了此闪烁单晶的氧气氛退火效应.结果表明,该单晶的透射光谱在400～800 nm波长区域呈现典型光学透过性,其吸收截止边位于380 nm左右,在紫外激发光或X射线激发作用下,此单晶具有峰值波长位于470 nm的荧光发射;此单晶经980℃温度下的氧气氛退火处理,其晶体着色有所变浅而光学透过性得以明显改善.     

钼酸镉单晶的坩埚下降法生长及其退火效应

以CdO和MoO3粉料为初始试剂,通过高温固相烧结合成CdMoO4多晶料,采用坩埚下降法生长出尺寸达φ25 mm×130mm的透明完整CdMoO4单晶;应用DSC、XRD对所获单晶进行了结晶相和热性能表征,测试了单晶的紫外可见透射光谱、紫外光激发发射光谱及其发光衰减时间.结果表明,CdMoO4单晶具有良好的一致熔融析晶特性,采用坩埚下降法较易于生长出大尺寸单晶;该单晶在吸收截止边375 nm以上波长具有良好光学透过性,在300 nm紫外光激发作用下,测得该单晶具有525 nm左右峰值波长的荧光发射,其发光衰减时间为804 ～ 1054 ns.该单晶经氧气氛高温处理呈现出明显的退火消色效应,即经1000℃以上温度的氧气氛退火处理,可使晶体的光学透过性得以明显改善,其荧光发射强度显著增强.     

非真空密闭条件下的Ce3+: LiYF4晶体生长

本文报道了氟化物激光晶体Ce3+: LiYF4的坩埚下降法生长工艺.以高纯氟化物LiF、YF3和CeF3为初始试剂,按照LiF: YF3: CeF3 = 51.5: 47.5: 1.0的物质的量比配料,经高温氟化处理合成严格无水的Ce3+: LiYF4多晶料.将Ce3+: LiYF4多晶料密封于铂坩埚中,添加少量聚四氟乙烯粉末,可避免氟化物熔体的氧化与挥发,从而在非真空条件下实现Ce3+: LiYF4晶体的坩埚下降法生长,成功生长出尺寸达28 mm×70 mm的无色透明完整单晶.采用XRD、差热/热重分析、透射光谱和荧光光谱对Ce3+: LiYF4单晶基本性质的进行表征.结果表明,该晶体在320~3000 nm区域内的光透过率达90;以上,晶体在297 nm处有一强吸收峰;荧光光谱显示晶体在紫外光区310 nm、325 nm处有两个强发射峰.     

Er3+:CaMoO4单晶的坩埚下降法生长与光谱性能

采用高温固相反应法合成Er3+:CaMoO4多晶料,通过坩埚下降法生长出1 mol; Er3+掺杂CaMoO4单晶;应用X射线粉末衍射证实了晶体材料的结晶物相,测试了退火前后单晶试样的透射光谱、吸收光谱、上转换荧光光谱和近红外荧光光谱,应用Judd-Ofelt理论计算了Er3+:CaMoO4晶体的光谱性能参数.研究表明,在980 nm激发光源作用下,从单晶试样获得较强的上转换绿色荧光发射,且呈现以1535 nm为中心波长的较宽荧光发射;经空气氛退火处理单晶试样的光学透过性得以改善,其上转换荧光发射和近红外荧光发射也得以明显增强.     

Nd3+∶YCa4O(BO3)3单晶的坩埚下降法生长与光谱性能

Nd3+:YCOB单晶是在激光调制技术上具有重要应用价值的自倍频光学材料.采用高温固相反应合成Nd3+∶YCOB多晶粉体,再通过垂直区熔处理制备出高纯度Nd3+∶YCOB晶粒料,采用坩埚下降法生长出1mol;、2mol;和5mo1; Nd3+掺杂比例的系列Nd3+∶ YCOB单晶.测试表征了所生长单晶试样的光谱性能,包括吸收光谱、荧光光谱和荧光衰减时间.在808 nm红外光源激发下,Nd3+∶YCOB单晶显示出中心波长1064 nm的强荧光发射,其荧光寿命为157～162μs,证实1064 nm强荧光发射随Nd3+掺杂浓度加大而明显增强.     

纯镁单晶制备研究

利用自制的硅碳棒加热单晶生长炉,采用改进的坩埚下降法,在最高温度900℃,坩埚相对下降速度约为1.7cm/h条件下,生长出直径约为φ50mm的纯镁单晶.通过X射线衍射、金相观察和测量电导率等手段研究分析了所生长镁单晶的晶体质量.     

坩埚下降法生长白宝石晶体的研究

本文报道了坩埚下降法生长大尺寸白宝石单晶.我们使用大尺寸异型钼坩埚,高纯氧化铝原料,在中性气氛下,结晶区温度梯度为25～30℃/cm,生长速度为0.8～1.8mm/h,生长方向选C面[0001]取向,成功生长出直径80mm,高度90mm的完整透明的白宝石单晶,在300～5500nm范围内,其光学透过率均在80;以上.实验中采用高性能保温材料使生长过程所需加热功率由20kW下降到15kW,能耗降低达25;;采用双回路加热系统,提高温场稳定性,缩短晶体生长周期.晶体的主要缺陷为顶部(生长后期)出现有5～10mm淡黄色色带(经在氧化性气氛中退火后已消除)和底部有细丝状条纹.     

坩锅下降法生长Nd3+∶LiYF4单晶及其光谱性能研究

以LiF∶ YF3∶NdF3=51.5∶47.5∶1为原料摩尔比,在50～60℃/cm固液界面温度梯度下,采用密封的坩埚下降法制备了尺寸为φ10 mm×50 mm的高质量Nd3+掺杂LiYF4单晶,并对产物的物相结构和光谱性能进行表征.结果表明,Nd3+在807 nm处的最大吸收系数α=1.96 cm-1,吸收跃迁截面为0.973 × 10-20 cm2.在808 nm LD激发下,测定了样品的荧光光谱和及最强荧光峰1050 nm(4F3/2→4I11/2)的荧光寿命(～451.0μs),并计算得到1050nm的最大受激发射跃迁截面为1.60×10-19 cm2.     

坩埚旋转下降法生长硒镓银单晶体

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;.     

坩埚下降法生长钨酸镉晶体的闪烁性能

以高温固相反应合成CdWO4多晶为原料,采用垂直坩埚下降法生长出大尺寸完整CdWO4晶体,就所生长CdWO4晶体进行了闪烁发光性能的测试表征,包括紫外可见透射光谱、光致发光光谱、光致发射衰减时间、X射线激发发射光谱、相对光产额以及γ射线辐照硬度.结果表明,该单晶在可见光区具有良好的光学透过性,其光致发光与X射线激发发射光的峰值波长位于475 nm左右,其光致发射衰减时间为842 ns;以CsI∶Tl晶体为基准样品,测得γ射线激发发光的光产额相当于基准样品的51.5％～57.4％,在γ射线辐照条件下其辐照硬度达107 rad.     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

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).     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

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 R_w=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.     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

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.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

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.     

Synthesis of spinacine and spinacine derivatives: crystal and molecular structures of Nπ-hydroxymethyl spinacine and Nα-methyl spinaceamine

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, N^π-hydroxymethyl-spinacine, and a spinacine derivative, N^α-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.     

X-ray Crystal Structures of [Et3NH][{(CO)5Mo(P(OCH2CMe2CH2O)O)}2H] and (CO)5Mo{μ-Ph2POPPh2}Mo(CO)5, Two Complexes Derived from the Hydrolysis of Coordinated Chloro-Phosphorous-Donor Ligands

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.      

Preparation,spectral studies and X-ray crystal structure of 1,3,5-triphenyl-1,5-pentanedione,C23H20O2

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.     

Isotope Effects in Liquid Crystal Systems: I: Phase Relationships in the Dodecylamine-H2O,Dodecylamine-D2O Systems

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.     

Spherulitic crystallization of β‐In2Te3 by physical vapour deposition

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)