共查询到19条相似文献,搜索用时 78 毫秒
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采用中频感应上称重提拉技术对Ca_2Al_2SiO_7(CAS)压电晶体进行了生长,研究了不同转速及生长方向下晶体的生长习性,从理论上分析了转速和生长方向对晶体形貌的影响。结果表明,晶体外形随转速的增加,其形貌由圆柱状变为正方形,再变为长方形,当转速到一定临界值时,晶体呈多晶状;随晶体生长方向的不同,晶体有不同的显露方向,并都有强的显露面(001)。对晶体不同显露方向进行了X线衍射分析,且对(001)面进行回摆测试。结果表明,晶体结构完整,结晶性能好。 相似文献
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高质量的碲锌镉单晶是制备碲镉汞红外焦平面器件的理想衬底材料,然而目前碲锌镉材料中的第二相夹杂物严重制约着晶体的质量.根据红外透射形貌的描述和表征,碲锌镉晶体的常见夹杂物被分成了五类,并在此基础上讨论了各自的形成机制,A、B和C类夹杂物与化学配比及其变化密切相关,而D和E类夹杂物与源材料中或者在生长工艺控制过程中氧含量相关.进一步的研究表明大尺寸、高密度的Te夹杂物将会严重降低红外透过率,同时腐蚀坑密集分布在与Cd夹杂对应的六重对称线上,该结果揭示了第二相夹杂物会产生其他缺陷的增殖,但夹杂物引起的应力影响区域是局限的. 相似文献
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本文讨论了在抽运氙灯、γ射线以及各种气氛中热处理作用下YAlO_3晶体内产生色心的吸收光谱。发现晶体的色心性质由生长条件决定而与钕离子无关。真空中生长的YAlO_3晶体实际上不被染色。氩气中生长的晶体在γ射线和紫外光辐照下以及热处理之后,出现同样的色心。不同结构色心的浓度比及其对光破坏的稳定性,取决于作用类型。 相似文献
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一、前言硬度是晶体重要的物理性质之一。对研磨工艺、矿物的鉴定及晶体机械特性(塑性、弹性极限、弹性模数和强度等)的研究有重要意义。硬度与晶体结构、晶体化学成份、晶体表面情形等密切相关。自1956年合成得到YAP晶体以来,对于这一晶体的显微硬度虽有过几次较含糊的报导,但对适于微观结构研究、测量方便、精确度高的维克尔显微硬度至今尚未有详细数据。 相似文献
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On the basis of both published data and our own experimental data we consider the main aspects of the problem related to ensuring polytype stability for ingots of grown 4H and 6H silicon-carbide compounds. 相似文献
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Electromigration of molten tin-based inclusions in single-crystal p-GaSb:Zn(111) was studied. It was shown that molten inclusions are displaced by a current (j=(1–4)×105 A/m2) toward a negative electrode in the temperature range T=750–920 K. The mechanism of this phenomenon was shown to be related to concentration changes in the bulk of molten inclusions. It was noted that the inclusion transport is initiated by two competing processes: the temperature changes at phase interfaces caused by the Peltier heat and the electric transport, leading to the redistribution of components, depending on their effective charges in the melt. The size dependence of the velocity of inclusion motion W in the bulk of a single-crystal matrix was determined: W increases with the inclusion size. The numerical values of the thermoelectric parameters of all the contacting phases were experimentally determined using independent methods. This made it possible, fitting the theory to the experimental data, not only to estimate quantitatively the effective charge Z* of a molten semiconductor, but also to explain the size dependence of the activation barrier overcome by a drifting inclusion. 相似文献
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BSO晶体的特性及其应用 总被引:2,自引:0,他引:2
本文概要地综述了Bi_(12)SiO_(20)(BSO)晶体的主要物理特性以及近几年来在实时全息术、斑纹干涉计量、光学信息处理等方面的应用和作者的一些实验结果。 相似文献
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G. W. Iseler 《Journal of Electronic Materials》1984,13(6):989-1011
By reducing the temperature gradients in the vicinity of the crystal-melt interface, 35-mm-diameter InP boules with much reduced
dislocation densities have been grown by the liquid-encapsulated Czochralski technique. A reduction in the residual donor
concentration of InP grown by this technique has been achieved by using In-rich charges prepared by adding elemental In to
polycrystalline InP ingot material. Nominally undoped crystals with carrier concentrations as low as 1–2 x4 1015 Cm − 1 and 77 K mobilities as high as 7.0 × 10 cm2 V−1 s−1 have been obtained. By growing doped crystals at increased seed or crucible rotation rates, short-range longitudinal variations
in dopant concentration have been reduced to a few per cent, as determined by optical absorption measurements with a scanning
CO2 laser. 相似文献
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色心晶体做为被动激光Q开关元件较染料开关有显著的优点:激光束畸变小、破坏阈值高和可在高重复频率条件下工作等。积极探索不同种类的色心调Q晶体适应不同波长激光器是很有意义的。对宽带可调谐紫翠宝石激光器来说,色心晶体有与之匹配的宽吸收带,可在整个调谐区内实现调Q,其优点更为突出。 紫翠宝石(BeAl_2Q_4:Cr~(3+))激光器是室温下运转的终端声子激光器,调谐范围在700~800nm之间,发射中心波长在750nm附近,和棒内温度有关。根据波长匹配原则——激光发射波长和色心吸收带峰相重合,我们选择了两种色心晶体对其进行调Q。一为LiF:F_3~-色心晶体,一为NaF:F_2~+色心晶体。二种基质材料在上述激光波长上的吸收均很小。利用 相似文献