Investigation of electronic, optic and mechanical properties of Re2O3 (Re: Gd, Tb ve Dy) compounds: AB initio calculation

In this thesis, the electronic, optical, and mechanical properties of hexagonal Gd2O3, Tb2O3 and Dy2O3 compounds were examined using the Density Functional Theory (DFT) method with the Generalized Gradient Approximation (GGA). The effects of Gd, Tb, and Dy atoms on the electronic structure of the Re2O3 compound were investigated. To better understand the nature of the electronic band structure of Gd2O3, Tb2O3 and Dy2O3 compounds, the density of states (DOS) was calculated. Complex dielectric function was calculated to investigate the optical properties of Re2O3 compounds. Optical properties such as reflection, electron energy loss function, refraction, absorption, and extinction coefficient were determined by using the real and imaginary parts of the complex dielectric function. Additionally, effective optical dielectric constant (εeff) and effective number of valence electrons (Neff) were computed using the imaginary part of the dielectric function. In order to study the mechanical properties of Re2O3 compounds, the second order elastic constants were calculated and the mechanical stability of the material was determined. In addition, bulk modulus (B), shear modulus (G), Young's modulus (E), elastic wave velocities and Debye temperatures (ΘD) were calculated by using the calculated single crystal elastic constants. Furthermore, the macro and micro hardness of Re2O3 compounds were calculated. Additionally, the anisotropic properties of all three compounds were investigated.