Al_2O_3从CaIrO_3结构转变为U_2S_3结构的相变对其高压下光学性质的影响

The effects of the CaIrO_3-U_2S_3 structural transition in Al_2O_3 on optical properties under high pressure

采用基于密度泛函理论(DFT)的第一性原理方法,计算了Al_2O_3晶体在高压下的光学性质.结果表明:(1)Al_2O_3从CaIrO_3结构转变为U_2S_3结构:将使得其吸收谱主峰值强度增强、副峰值强度显著减弱、主副谱峰均红移以及光谱吸收边出现巨大的红移.(2)结构相变将引起Al_2O_3折射率谱峰值强度减弱和谱峰数增加;同时,在波长为400-2000 nm的范围内,结构相变将导致Al_2O_3折射率显著增大.本文的计算结果为未来进一步的实验研究提供了参考信息.

The optical properties of Al2O3 crystal under high pressure were calculated by using the first-principles method based on density functional theory （DFT）. The results show that： （1） The CaIrO3-U2S3 structural phase-transition leads to the increase of main-peak intensity, the evident decrease of additional-peak intensity and the red shifts of main and additional peaks and absorption edges in Al2O3 absorption spectrum. （2） The structural phase-transition leads to the decrease of the peak intensity of the Al2O3 refractive index, the increase of the peak number and the enhancement in refractive index at the wavelength range of 400-2000 nm. Our results may be important for future experimental study.