The effect of oxygen vacancy on structures and optical properties of the lead-free Ba0.5Sr0.5TiO3 by first-principles calculation

Abstract

Abstract. The structural and optical properties of lead-free Barium strontium titanate Ba 0.5 Sr 0.5 TiO 3 with oxygen vacancies (BST-O) were investigated by first-principles calculations of density functional theory. The results show that the O vacancy has significant influence on the electronic structure and optical performance of the materials. The structures generate a phase transition from cubic to tetragonal phase, when an O atom has removed from the pure Ba 0.5 Sr 0.5 TiO 3 (BST). The electron density conformation is distributed, which induce conspicuous distortion of the oxygen octahedron. The calculated optical properties, complex dielectric function, refractive index, absorption coefficient, show that the absorption spectra of the BST-O have multimodality and smaller amplitude by comparing with ideal BST. And the oxygen vacancy lead the increase of refractive index and the decrease of absorption coefficient in visible light frequency region (1.59~3.11 eV), the optical anisotropism is also found in the BST-O.