四方相钛酸钡晶体的晶格动力学

建立了四方相钛酸钡铁电晶体的晶格动力学壳层模型，氧离子的极化是各向异性的，模型的参数值由拟合Г点的声子谱实验数据确定。计算了声子色散关系，态密度和晶体的弹性常数，在弹性常数计算中计及了压电体中声子谱长波区域内声学模和低频光学模的耦合，计算结果比刚性离子模型有明显的改善。

Lattice Dynamics of Barium Titanate Crystal in the Tetragonal Phase

A shell model is used to study the lattice dynamics of the ferroelectric bariumtitanate crystal in the tetragonal phase. The polarization of the oxygen ions is considered to beanisotropic. The parameters of our model was obtained by fitting experimental date of thefrequencies of zone-center phonons. The phonon dispersion curves and the density of states werecomputed.The strong coupling between the acoustic and the low-frequency optic modes in thelong-wavelength region is involved in the calculation of the elastic constants of this piezoelectriccrystal.It is shown that the results of the shell model is better than that of the rigid ion model.