排序方式: 共有13条查询结果,搜索用时 15 毫秒
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反铁畸变中钛酸锶(SrTiO3)晶体学原胞的选取 总被引:2,自引:0,他引:2
通过对钛酸锶(SrTiO3)在相变前后结构对称性的分析,提出了与之相应的两种晶体学原胞的选取方法。无论选取D4和D2d哪一种原胞,其对称元素个数均为8,即对称元素个数保持不变,只是所选原胞体积相差一倍。因此,在选取原胞时必须遵从以下两个原则:1)所选晶体学原胞的体积在相变前后要保持不变;2)所选取的晶体学原胞,应最能反映相变前后晶体结构对称性的变化,且其对称元素个数不因所选原胞体积的不同而变化。 相似文献
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利用晶体中弹性波的微分方程,求解出慢度曲面极大值的方向,从而确定其软模及偏振态,根据居里原理来确定晶体铁弹相变前后结构对称性。可根据弹性系数随温度的变化规律找出相变温度。得到的结果与实验相吻合。 相似文献
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利用慢度曲面及偏振态研究六方晶系晶体的铁弹相变 总被引:1,自引:0,他引:1
通过慢度曲面上最大慢度来确定六方晶系振动模软化最突出的方向,根据振动模的偏振态确定软模本征矢,从而确定铁弹相变前后结构对称性的变化。 相似文献
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叠层多结光电池结构和电流匹配研究 总被引:1,自引:1,他引:1
根据测得的ZnSe p—n结的外量子效率(QE)曲线,研究了ZnSe/GaAs/Ge叠层多结光电池的ZnSe顶电池结构、优缺点及全电池的电流匹配问题,探讨了用Au/i—ZnSe/n—ZnSe肖特基结金属/绝缘体/半导体(MIS)结构取代ZnSe p—n结结构从而改进全电池性能的方法。研究表明,改进后的ZnSe/GaAs/Ge叠层多结电池具有开路电压高、阳光光谱覆盖率高、电流匹配较好及工艺较简单等优点。 相似文献
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FromEinstein’s supposition aboutcrystal lattice vi-bration, which states that the vibration frequency of ev-ery crystal lattice is the same, the balance of heat ener-gy in the crystal can be written out using the theory ofstatistical thermodynamics, so that the molar heat capac-ity under normal temperatures can be easily calculated.For many kinds of metals, the theoretical value of themolar heat capacity is close to the experimental value.In other kinds of metals, though, especially metals of… 相似文献
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This paper is based on Einstein‘s supposition about crystal lattice vibration, which states that when Einstein‘s temperature ΘE is not less than the crystal temperature T but less than 2T, the expression of crystal molar heat capacity changes to the Dulong-Petit equation Cv= 3R. Thereby this equation can explain why crystal molar heat capacity equals about 3R not only at low temperatures but also at normal temperatures for many kinds of metals. It can be calculated that the nonlinear interaction among atoms contributes to the molar heat capacity using the coefficient of expansion β and the Griineisen constant γ. The result is that the relative error between the theoretical and the experimental value of the molar heat capacity is reduced greatly for many kinds of metals, especially for metals of IA. The relative error can be cut by about 17%. 相似文献
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