共查询到17条相似文献,搜索用时 62 毫秒
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以高纯硼酸、碳酸锂和碳酸铯为原料,摩尔比硼酸:碳酸锂:碳酸铯=11:1:1,采用顶部籽晶法,生长出尺寸为65 mm×22 mm×12 mm CsLiB6O10(CLBO)单晶,探讨了影响CLBO晶体生长的因素.对生长出的CLBO晶体的相关光学性质进行了研究.CLBO晶体的光学均匀性为3.6×10-5/cm,透过光谱表明该晶体的透光范围为185 nm到2790 nm,其紫外吸收边低于185 nm;用Maker干涉条纹测定了CLBO晶体的非线性光学系数为:d36(CLBO)=1.8d36(KDP). 相似文献
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采用FLUENT软件对分离结晶Bridgman法生长CdZnTe晶体进行了全局数值模拟.模拟对象为:熔体上部边界条件分别为固壁和自由表面时两种晶体生长系统.重点考虑坩埚和晶体之间狭缝宽度e和重力对分离结晶过程的影响.在计算中分别取e=0 mm、0.5 mm和1 mm三种狭缝宽度,得到了在微重力和常重力条件下的温度分布、结晶界面形状以及流函数分布图.结果表明:在微重力条件下,当熔体上部为固壁时,随着狭缝宽度的增大,热毛细力作用增强,流动强度增强;当熔体上部为自由表面时,则与之相反.在常重力条件下,由于浮力-热毛细对流的共同作用,随着狭缝宽度的增加,流动强度逐渐减弱,有助于提高晶体生长质量. 相似文献
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采用垂直布里奇曼法(VB法)生长2英寸GaSb单晶,分析了GaSb多晶产生的原因,即GaSb原料与覆盖剂中残留水分发生化学反应生成氧化镓残渣,残渣吸附在坩埚内壁导致GaSb多晶形成.通过增加覆盖剂除水工艺,成功生长出2英寸高质量GaSb单晶.此外,研究了单晶内部位错分布特点,结果显示GaSb晶体具有较低的位错密度,EPD≤500 cm-2;同时,对晶体进行XRD摇摆曲线测试,其FWHM值为27 arcsec,表明晶体质量较高;此外,对晶体进行了电学性能测试,结果显示制备的GaSb晶体呈P型导电,晶体迁移率为610 cm2/V·s,载流子浓度达到了1.68×1017cm-3. 相似文献
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本文首次采用顶部籽晶泡生法在敞开体系中生长了出了磁光晶体硼酸铁单晶。选用B2O3作自助溶剂,LiF作稀释剂,确定了原料配方。对长出的晶体作了初步的物化性能测试。讨论了晶体生长的结果。 相似文献
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硒铟锂(LiInSe2,LISe)晶体在长波红外激光领域有重要应用价值.目前高质量、大尺寸LISe晶体的稳定生长仍然面临挑战,通过气氛退火后处理工艺能够有效提高晶体光学质量.本文采用定向籽晶垂直布里奇曼法,通过精确控制籽晶熔接,实现大尺寸(φ40 mm×60 mm)LISe晶体的批量稳定制备,为目前国际上报道的最大尺寸LISe晶体.另外,系统探索了LISe晶体的退火工艺,研究表明在740℃、LISe本征气氛下退火150 h,可以明显提高LISe晶体器件光学质量. 相似文献
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本文报道了KI单晶在非真空密闭条件下的坩埚下降法生长.以经充分干燥的高纯KI多晶为原料,将KI多晶料密封于套层铂坩埚中,添加少量活性碳粉末,可避免碘化物熔体的氧化与挥发,从而在非真空条件下实现KI单晶的坩埚下降法生长.在晶体生长过程中,炉体温度调节于750~770 ℃,固液界面温度梯度为30~40 ℃/cm,坩埚下降速率控制为1~2 mm/h,成功生长出尺寸为φ25 mm×50 mm的透明完整KI单晶.采用XRD、DTA-TG、透射光谱、荧光光谱对所获KI单晶进行了测试表征,结果表明该单晶具有良好的光学均匀性,在450~2500 nm波长范围的光学透过率达70;以上,其光学吸收边位于280 nm左右;在266 nm脉冲光激发下,该单晶具有397 nm峰值波长的荧光发射. 相似文献
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以K2O为助熔剂,在较大的温度梯度(90~100℃/cm)条件下进行引种和晶体生长,应用坩埚下降法成功地生长出了初始CO2+掺杂浓度为0.5mol;的近化学计量比的铌酸锂晶体.测定了该晶体的红外光谱与吸收光谱,与同成份的LiNbO3晶体相比,其紫外吸收边向短波方向移动,OH-红外吸收峰的位置发生变化.观测到520,549,612nm三个分裂的尖吸收峰以及1400nm左右为发光中心的吸收带.从吸收特性可以判断,Co离子在铌酸锂晶体中呈现+2价.比较上部与下部晶体的吸收强度,可以推测出沿着晶体生长方向Co2+离子浓度逐渐降低,Co2+离子在晶体中有效的分凝系数大于1. 相似文献
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PIMNT单晶是近年来最新发现的弛豫铁电晶体材料,该三元固溶体单晶具有比较理想的压电、铁电和介电性能,本文报道了大尺寸PIMNT单晶的熔体坩埚下降法生长的实验研究结果。采用固相合成钙钛矿相多晶料,采用垂直坩埚下降法成功生长出最大直径为3英寸的PIMNT单晶;从所生长单晶原胚的三方相区段切割加工出(001)取向晶片,就(001)晶片的介电、压电及铁电性能进行了测试表征,表明其材料性能能够满足相关超声换能器件制作的实用需求。本论文还着重讨论了PIMNT单晶生长所涉及的系列关键技术问题,如富铅熔体对铂金坩埚的侵蚀、晶体原胚的单晶性表征、晶体生长过程的组分偏析与单晶原胚的性能分布等。 相似文献
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A set of experiments on the solidification of Ga 1-x In x Sb alloys with a large variation of the sample diameter (from 1mm to 10mm), of the growth rate (from 0.7 to 7 μm/s) and of the concentration (from x=0.01 to x= 0.1) is described. The associated radial and longitudinal segregation of the In have been analysed by SIMS or electron microprobe. Numerical simulation of the experiments, taking into account thermal, hydrodynamic and chemical behaviour has been carried out with the help of FIDAP. It is shown from these numerical results that a plateau of concentration can be reached even if a convective loop is present close to the interface, provided that the convection does not extend into the bulk of the liquid. This is in full agreement with the experimental results obtained. Supporting this analysis, in some experiments, a defect in term of verticality of the crucible led to complex 3-D convection involving the whole liquid, and in that case no plateau was obtained. For the radial segregation ΔCR, three regimes of transport are found, characterised by the convective level: - A diffusive one, with a low, constant, ΔCR related to the interface curvature. - A quasi-diffusive one (weak convection) in which ΔCR increases with convection. - A convective one in which it decreases. Measured radial segregations are in good agreement with predictions from the numerical simulations. 相似文献
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In this work the momentum and heat transfer on a Bridgman system for the growth of GaSb has been studied. The main objective was to obtain some information about the role of the different processes like conduction, radiation and convective effects both in the melted material and the surrounding environment. These simulations are based on a 2D axi‐symmetrical model using a finite element method based code. The simulations have been carried out both in steady and transient states. It has been demonstrated that the consideration of a moving environment is important in the distribution of temperatures. The effects of the variations of thermal conductivities and emisivities on the thermal and velocity fields have been investigated. The results show that the key parameters are the thermal conductivities of the different materials present in the system, which produce significant changes in the convective flows inside the melt. 相似文献