LiRb_5(SO_4)_3·1.5H_2SO_4晶体铁弹相变的研究

Study on Ferroelastic Phase Transition of LiRb_5(SO_4)_3·1.5H_2SO_4

本文利用慢度曲面法研究LRSHS晶体的铁弹相变。画出了LRSHS晶体在发生铁弹相变过程中一些温度下的慢度曲面图,得到了最大慢度。研究结果表明:晶体在三维空间的慢度最大值方向就是发生本征铁弹相变的方向,即声学软模软化的方向。确定出声学模的软化方向,即可确定出发生本征铁弹相变时软化显著的弹性劲度系数,再利用居里原理即可得到晶体铁弹相的对称性。

The slowness surface method is used to study the ferroelastic phase transition of LRSHS crystal. The slowness surfaces of LRSHS crystal have been plotted at some temperature, and the maximum slowness has been calculated and shown. The results of the study show that the direction of the maximum slowness is the direction of the ferroelastic phase translation happening. Namely, it is the softening direction of the acoustic soft mode. And the elastic coefficient which softens remarkably during phase transition is determined. The symmetry of the ferroelastic phase of the crystal is obtained by using Curie principle.