Estudo DFT das propriedades estruturais, eletrônicas e ópticas do cristal do trióxido de tungstênio

Abstract

In recent years, due to its semiconductor characteristics and potential industrial application, WO3 has attracted considerable attention and interest. Thus, in this work, we investigate the structural, electronic and optical properties related to cubic, orthorhombic, tetragonal and monoclinic crystals. All properties of interest were obtained from the theory of functional density using the generalized gradient approximation method. Our numerical results corroborate with experimental data, confirming the semiconductor character of the WO3 crystal. A peculiar result is that presented by the tetragonal crystalline phase, in which a gap value around 0,18eV is provided, relatively smaller than the other phases, characterizing, in addition, a pseudo-direct transition. On the other hand, we obtained an indirect transition (R → Γ) for the cubic phase and direct transition (Γ → Γ) for the orthorhombic and monoclinic crystalline phases. As for the calculations of partial density states, the largest contribution for the valence and conduction bands corresponds to the p and d orbitals, both related to the oxygen and tungsten atoms, respectively. We still find a low degree optical anisotropy for the absorption coefficient and dielectric function.