三元混晶的远红外光谱

采用无序元素孤立位移模型(REI mode)，建立了三元混晶AB_1-xC_x晶格动力学的Born-Huang方程，并由此出发讨论了几种三元混晶晶格振动的介电常数和远红外反射谱。理论计算结果表明，这个模型适用于三元混晶的所有情况：(1)单模情况——在整个成分比例区域内(0≤x≤1)有1支横光学声子(TO)和1支纵光学声子(LO);(2)双模情况——在整个成分比例区域内(0≤x≤1)，有2支横光学声子和2支纵光学声子;(3)第3种情况——部分区域为单模而另外区域为双模。结果显示，单模晶体只有1个反射带;双模晶体有2个反射带;第3种类型的晶体在部分区域有1个反射带而在另外的区域有2个反射带。该理论模型提供了一个理解三元混晶光学性质的可能的途径，依此为基础可以讨论电子-声子相互作用等其他问题。

The Far-Infrared Spectrum of the Ternary Mixed Crystal

Born-Huang equations of lattice dynamics for the ternary mixed crystal AB(1-x)Cx. by using the random-element-isodisplacement model (REI model) were set up, and the dielectric function and the far-infrared reflectivity of lattice vibration in several ternary mixed crystals were discussed. It is shown that this model applies to all circumstances: (1) Single mode--there are one transverse optical phonon and one longitudinal optical phonon in all scope of the composition x(0 < or = x < or =1). (2) Double mode--there are two TO-LO-mode pairs in 0 < or = x < or = 1. (3) The third mode--it shows single mode behavior in a part and shows double mode behavior in another part. It was found that single mode crystal has one reflectance band and double mode has two reflectance bands. For the third mode crystal, there are one band in a part and two bands in another part. The model provides a possible way to understand the optical character of other problem of electron-phonon interaction. mixed crystal. Based on it the authors can discuss other problem of electron-phonon interaction.