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采用基于密度泛函理论(DFT)的第一性原理CASTEP计算程序,研究Al2O3的能带结构和光学函数。结果表明,α-Al2O3和γ-Al2O3的能带结构形状相似,γ-Al2O3的高对称性使得费米面向高能级方向移动,进入导带;对于较常见的几种波长激光,α-Al2O3的介电函数虚部均为0,实部随着激光波长增大而减小;γ-Al2O3的介电函数虚部、实部随着激光波长增大而增大。γ-Al2O3的介电函数虚部、实部和反射率均高于α-Al2O3,在激光波长为10.6μm时反射率最高,达到40.1%,为α-Al2O3的7倍。
The first-principles CASTEP calculation program based on density functional theory (DFT) was used to study the energy band structure and optical function of Al2O3. The results show that the band structures of α-Al2O3 and γ-Al2O3 are similar. The high symmetry of γ-Al2O3 makes the Fermi move towards the high energy level and enters the conduction band. For the more common types of laser, the α-Al2O3 The imaginary part of the dielectric function is 0, and the real part decreases with the increase of the laser wavelength. The imaginary part and the real part of the dielectric function of γ-Al2O3 increase as the laser wavelength increases. The imaginary part, real part and reflectivity of the dielectric function of γ-Al2O3 are higher than that of α-Al2O3. The reflectivity of γ-Al2O3 is 40.1% at the wavelength of 10.6μm, which is seven times that of α-Al2O3.