高压下BaLiF3晶体光学性质的第一性原理研究

Optical properties of BaLiF crystal at high pressure:A first-principles study

本文采用第一性原理方法,在190 GPa的压力范围内,计算了BaLiF3理想晶体和含空位点缺陷晶体的光学性质.吸收谱数据表明,压力因素不会导致BaLiF3晶体在可见光区有光吸收的行为.空位点缺陷的存在会使得BaLiF3的吸收边红移(其中氟空位点缺陷引起的红移最显著),但这些红移不会导致它在可见光区内出现光吸收的现象.波长在532 nm处的折射率数据显示,BaLiF3的折射率将随压力升高而增大.氟空位点缺陷将导致BaLiF3的折射率增大,但钡空位点缺陷和锂空位点缺陷的存在对其基本没有影响.本文预测,BaLiF3晶体有成为冲击光学窗口材料的可能.

The optical properties of BaLiF3 crystal without and with vacancy defects within pressure 190 GPa were calculated by using the first-principles method.The absorptive data show that the pressure factor cannot alter a fact that there is no light-absorption for BaLiF3 in the visible region within 190 GPa.The barium,lithium and fluorine vacancy defects in BaLiF3 lead to the red-shift of its absorption edge(the influences of fluorine vacancy defects are the most apparent),but all these red-shift behaviors do not give rise to its light absorption in the visible region.The refractive-index data at 532 nm indicate that the BaLiF3 refractive index increases with increasing pressure.The fluorine vacancy defects cause an increase in refractive index,but influences of the barium and lithium vacancy defects are very slight.We predict that BaLiF3 crystal is possible to be an optical window material in shock experiments.