共查询到17条相似文献,搜索用时 140 毫秒
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通过对K2WO4和K2W2O7两种助溶剂的对比、分析,选择K2W2O7做助溶剂,采用顶部籽晶(TSSG)法生长YbKGW晶体.设计了合理的工艺条件转速10~15r/min;降温速率0.05℃/h;生长周期15d.通过对YbKGW晶体粉末样品的X-ray衍射谱与KGW粉末样品的X-ray衍射谱对比分析,生长晶体为β-YbKGW晶体.利用TG-DTA测定YbKGW晶体的熔点及相变温度分别是1086℃和1021℃.通过对晶体缺陷的观察分析认为,晶体裂缝及包裹物等缺陷与生长工艺条件密切相关,应尽量减少生长过程中的温度、浓度及生长速度的波动,保持晶体的稳态生长. 相似文献
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DUAN Lihua LIAO Kejun WAN Buyong CHEN Ning HU Jianping ZHANG Wenhui 《材料导报》2004,18(Z3):102-104
分析了HF酸腐蚀时间对熔石英抗激光损伤阈值的影响.用浓度为4%的HF酸腐蚀15min后,测得熔石英抗激光损伤阈值提高了53.1%,并对其机理作了分析.激光损伤实验使用波长为355nm,脉宽为10ns,频率为3Hz的Nd:YAG调Q激光器测试系统.当泵浦激光辐照熔石英样品表面时,后表面比前表面更容易发生激光诱导损伤,HF酸腐蚀的程度对前后表面抗激光损伤阈值比基本没有影响.对实验样品在HF酸腐蚀前后表面粗糙度的测量结果表明,HF酸腐蚀时间较短时实验样品表面粗糙度基本无变化,如果选用的样品存在较多的表面及亚表面缺陷,当HF酸腐蚀去除掉重沉积层后,表面粗糙度将急剧上升. 相似文献
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温度梯度和生长速率对CdZnTe-VBM生长晶体的影响 总被引:3,自引:0,他引:3
计算模拟了半导体材料CdZnTe垂直布里奇曼法(CdZnTe-VBM)单晶体生长过程,分析了炉膛温度梯度和坩埚移动速率对结晶界面形态和晶体内组份偏析的影响。计算结果表明炉膛温度梯度和生长速率的变化明显影响固-液界面前沿对流场的形态和强度。界面凹陷深度随着炉膛温度梯度的增加和生长速率减小而减小。炉膛温度梯度的增加和生长速率的减小虽然均能有效的减小径向偏析,但却增加轴向偏析,减小轴向等浓度区的长度。 相似文献
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A nickel-based superalloy was deposited onto a single crystal substrate based on epitaxial laser metal forming(E-LMF). The microstructure development in two depositions has been researched. For the first time, the crystal orientation of dendrites varying beyond 20° was found when the dendrites deflected in deposition. In addition, a new grain boundary was found between different orientation dendrites in a grain, and the detected grain boundary angle was 23°. The result shows that flowing field in laser pool is responsible for this phenomenon. 相似文献
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Jianqin Zhang Shenglai Wang ChangShui Fang Xun Sun Qingtian Gu Yiping Li Bo Wang Bing Liu Xiaoming Mu 《Materials Letters》2007,61(13):2703-2706
KDP crystals were grown from the aqueous solution with different concentrations of sulphate by both the traditional temperature-lowering method and the rapid growth method. Sulphate showed a great effect on the growth and the properties of KDP crystals. With the rise of the dopant concentration, many defects occur such as mother liquid inclusions, parasite crystals and cracks. When the dopant concentration of sulphate reaches a certain value, the ultraviolet transmittance of crystals decreases a lot compared with crystals at low dopant concentration. 相似文献
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YCOB晶体生长与激光倍频性能研究 总被引:2,自引:0,他引:2
坩埚下降法沿<010>和<001>方向生长了直径达到25mm的完整透明的Ca4YO(BO3)3 (YCOB)晶体.化学腐蚀结果表明,所生长晶体无孪晶或亚晶界等缺陷,晶体尾部的位错密度 不超过1800/cm2测量了YCOB的透射光谱,其截止波长为200nm进行了YCOB晶体对 Nd:YAG激光的二次倍频实验.通过与KDP晶体对比,计算出YCOB晶体的有效非线性系数 在Ⅰ型相位匹配方向(θ,φ)=(66.3°,143.5°)和(65.9°,36.5°)上分别为1.45pm/V和0.91pm/V; 大于KDP和 LBO晶体.在脉冲宽度10ns的 Nd:YAG激光单脉冲辐射下YCOB晶体出现体 损伤的激光损伤阈值不低于85GW/cm2. 相似文献
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