First-Principles studies on the Electronic and Optical Properties of Corundum samples from the Tanga region

Abstract

The characteristics of corundum are significant as they provide accurate identification supporting its diverse applications, facilitating the development of advanced materials, and ensuring its optimal use across various fields. Corundum alumina (α-Al₂O₃) samples collected from the Tanga mining region were characterized for crystallographic information using XRD analysis. This crystallographic information was used to build the crystal system of the sample in Biovia Materials Studio modelling and simulation software. The electrical and optical properties of this sample were examined by applying first-principles density functional theory and Generalized Gradient Approximations. For the calculations, a sampling mesh of 6×6×2 k-points, with an energy cut-off of 600 eV, and an energy convergence within 1.0 x 10^-5 eV/atom were used. The band gap determined is 6.34 eV at the gamma point exhibiting an insulating property. By plotting their polarized dielectric function in various directions, the optical properties were evaluated. The reflectivity spectra exhibited anisotropic behaviour in the ultraviolet region, enhancing its performance in various electronic and photonic applications. Also, the absorption peaks observed are 64.81 nm along [001] crystalline direction and 65.29 nm along [100] and [010] crystalline directions.

Keywords:    First-Principles studies; Corundum; Band gap; Polarized and anisotropic reflectivity