共查询到18条相似文献,搜索用时 109 毫秒
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掺杂YCa4O(BO3)3晶体的生长与性质研究 总被引:1,自引:1,他引:0
采用提拉方法,首次使用铂坩埚在大气气氛下生长出大尺寸,高质量的非线性光学晶体YCa4O(BO3)3(YCOB).典型晶体尺寸为直径15~20mm,长度30~40mm.对晶体进行掺杂改性研究,已分别生长出掺杂浓度为5;的Nd:YCOB,Er:YCOB和掺杂浓度为20;的Yb:YCOB晶体.对沿不同方向生长的晶体的习性和缺陷进行了研究.晶体的生长是以典型的二维成核层状生长进行的.当沿方向生长时,晶体易出现(010)面孪晶及方向的解理面;而沿〈010〉方向生长时,可避免孪晶和解理面的出现.我们认为〈010〉方向为最佳生长方向.通过测量晶体的室温透过谱发现掺杂的YCOB晶体在深紫外(220nm)有较高的透过率(80;).初步的自倍频实验可观察到Nd:YCOB晶体能够在811nm的LD泵浦下产生较强的绿光,并且阈值较低.这表明掺稀土的YCOB晶体可能是一种有应用前景的自倍频激光材料. 相似文献
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用于红外变频的大尺寸AgGaS2晶体生长 总被引:5,自引:4,他引:1
在红外变频非线性光学应用中需要高光学质量大尺寸AgGaS2晶体元件.我们采用改进的Bridgman方法生长直径28mm、长度60~80mm的晶体棒.成功生长的关键是要采用C向籽晶.[001]籽晶生长的晶体中很少发现裂纹、聚片孪晶等宏观缺陷.在Ag2S共存下的热处理能有效地排除晶体中的异相沉淀,显著改善透明度.我们制备的Ⅰ型相位匹配8mm×10mm×16mm和5mm×5mm×15mm?AgGaS2晶体元件分别成功地应用于差频、和频激光实验. 相似文献
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冷心放肩微量提拉法大尺寸蓝宝石单晶生长过程的模拟分析 总被引:4,自引:1,他引:3
利用数值模拟方法计算了冷心放肩微量提拉法(SAPMAC)蓝宝石晶体生长过程.结合晶体直径变化、裂纹出现位置与延续方向、晶体透明性等实验现象,通过与提拉法、温梯法、坩埚移动法等相对比,分析了冷心放肩微量提拉法晶体生长各阶段的工艺特点,并根据模拟计算结果对晶体生长系统和晶体生长控制工艺进行了改进.分别利用增大热交换器的散热参数、降低加热温度、改进降温曲线、调节外加轴向和径向温度梯度的方式来实现对晶体生长的引晶、放肩、等径和收尾控制.通过实验比较证明了改进后的晶体生长系统和晶体生长控制工艺能够生长出性能较好的大尺寸蓝宝石晶体. 相似文献
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采用垂直布里奇曼法生长了尺寸为φ30 mm×120 mm的Cd0.8Mn0.2Te晶锭.采用X射线粉末衍射及X射线双晶摇摆曲线分析了晶体的结构与结晶质量,结果显示所生长的晶体为单一立方闪锌矿结构,半峰宽为47.2aresec,结晶质量良好.采用化学腐蚀方法显示了晶体中的多种缺陷,包括位错,Te夹杂和孪晶.采用光学显微镜,扫描电镜和X射线能谱仪对缺陷形态和分布进行了研究.结果表明,晶体中位错密度在105~106cm-2之间.晶体局部存在Te夹杂相,尺寸为l~5μm.晶体中孪晶主要以共格孪晶存在.并提出了缺陷形成的原因和减少缺陷的方法. 相似文献
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垂直Bridgman法生长Cd1-XMnxTe晶体的缺陷研究 总被引:1,自引:0,他引:1
本文采用垂直布里奇曼(Bridgman)法生长了尺寸为Φ30 mm×130mm的Cd1-xMnxTe晶体,利用Nakagawa腐蚀液显示了晶体的位错、Te夹杂相和孪晶缺陷,并采用傅立叶变换红外光谱仪研究了晶体的红外透过率与晶体缺陷之间的关系.结果表明:生长态Cd1-xMnxTe晶体的位错密度为104~105 cm-2,Te夹杂相密度为103~104cm-2,晶体中的孪晶主要为共格孪晶,孪晶面为[111]面,且平行于晶体生长方向.在入射光波数4000~500 cm-1范围,晶体的红外透过率为36.7;~55.3;,红外透过率越大,表明晶体的位错和Te夹杂相密度越低,晶体对该波长范围的红外光表现为晶格吸收和自由载流子吸收. 相似文献
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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
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An unidirectional 60mm diameter benzophenone single crystal was successfully grown by utilizing a novel crystal growth method at room temperature. <110> oriented single crystal ingots were grown out of xylene as solvent and by fixing a seed at the bottom of the ampoule. The obtained benzophenone ingots with the sizes of 10mm, 25mm and 60mm diameter evident that ease in increasing the diameter of the ingot. The orientation of the ingot and the crystalline quality were justified by X‐ray studies. TG and DTA evaluated the thermal properties of the grown crystal. The optical transmission study and the powder SHG measurement show the suitability of the ingot for nonlinear optical applications. The achieved solute‐crystal conversion efficiency of hundred percent shows vital advantage of this technique for cost effectiveness. The microbial growth as in the case of amino acid based growth solutions can be more effectively controlled in the present method since the freshly prepared growth solution can be constantly made available to the growing crystal. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
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Lunyong Zhang Hongbo Zuo Fuyang Cao Dawei Xing Jianfei Sun Xiaohong Wang Jiecai Han 《Crystal Research and Technology》2012,47(2):175-182
A mathematical model has been proposed to design the process for growing a shaped crystals by Kyropoulos method or SAPMAC method. Crystal shape evolution behaviours under various processes were analysed. The results show that the crystal would go through a transitory shoulder‐expanding stage after which the crystal diameter rapidly decreases under a constant pulling rate and a constant heater temperature. Reducing pulling rate and heater temperature could depress the decrease of crystal diameter after the shoulder‐expanding stage so that enhance the length of crystal. However, the crystal diameter is more sensitive to pulling rate than to heater temperature, and an equal‐diameter crystal can not be grown in non‐undercooled melt by soley reducing the heater temperature. That means that adjusting the pulling rate is the most effective and convenient approach for controlling crystal diameter evolution and simultaneously decreasing both the pulling rate and the heater temperature is the optimal process for growing an equal‐diameter crystal. Moreover, a numerical approach for quantifactional designing crystal shape and corresponding growth processes was proposed according to the model, an example of crystal shape design was given out. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Cd1‐xMnxTe (x =0.2, CdMnTe) crystal was grown by the vertical Bridgman method, which exhibits a pure zincblende structure in the whole ingot. The major defect, twins, which is fatal to CdMnTe crystal, was analyzed with scanning electron microscopy (SEM), X‐ray energy disperse spectroscopy (XEDS) and optic microscopy on the chemical etching surface. The twins observed in the as‐grown ingot are mainly lamellar ones, which lie on the {111} faces from the first‐to‐freeze region of the ingot and run parallel to the growth axis of the ingot. Coherent twins with {115}t‐{111}h orientations when indexed with respect to both the twin and host orientations, are often found to be terminated by {110}t‐{114}h lateral twins. Te inclusions with about 20 μm in width are observed to preferentially decorate the lamellar twin boundaries. The origin of the twins, relating to the growth twin and the phase transformation twin, is also discussed in this paper. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Lunyong Zhang Hongbo Zuo Jianfei Sun Xiaohong Wang Jiecai Han Dawei Xing 《Crystal Research and Technology》2011,46(10):1019-1026
This paper proposes a geometric model for crystal growth by pulling. On the basis of the model, effects of the growth processes on the evolution of crystal shape were studied. Besides some effects already adopted in practice to control the crystal diameter, our results revealed several novel effects: a crystal grown under fixed process parameters could grow with a self‐stabilized diameter after shoulder‐expanding; decreasing the convex degree of solid liquid interface would enhance the increasing rate of crystal diameter or reduce the decreasing rate of crystal diameter. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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A LaCoO3 single crystal with 4 mm in diameter and 30 mm in length has been grown by optical floating zone method. The as‐grown crystal is highly crystalline with the rhombohedral perovskite structure (R3c) and grows parallel to the (121) direction. The room temperature resistivity of the as‐grown crystal is 0.12 Ω·cm and the insulator‐metal transition occurs around 500 K. The coercivity and the remanence of the as‐grown crystal are 5 Oe and 6.61×10–5 μB/f.u. at 5 K, respectively. In 1000 Oe under zero‐field cooling, the magnetic susceptibility of the as‐grown crystal shows an upturn in a Curie tail fashion below 35 K, and appears a wave crest over the interval 55 K≤T≤90 K. In addition, a slope change of 1/χ(T) at about 12 K is observed in 50000 Oe under zero‐field cooling. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献