Study of electronic structure and optical properties of monoclinic Na_(0.2)TiO_2

The band gap,density of states,electron density of monoclinic Na0.2TiO2 were simulated by using the plane wave pseudo potentials(PWPP) based on the density functional theory(DFT).Calculated results show that Na0.2TiO2 is an indirect semiconductor with the band gap of 2.81 eV.The density of states is mainly made up of Ti 3d and O 2p.The material has strong broadband UV absorption,extends the range of spectral response and increases utilization rate of solar energy and photocatalytic efficiency.While the Na and O atoms is connected by a strong ionic and weak covalent mixed bond,the Ti—O bond is shorter and has more covlent component than Na—O bond.This work may provides a theoretical guid for the molecular design and applications of Na0.2TiO2 and related materials.Therefore,the bond characteristics and stability of sodium titanate can be changed by cation-exchange.