Theoretical study of stability and optical absorption properties of ferroelectric materials ZnXO3 (X=Ge, Sn and Pb)

Abstract

The chemical potential equilibrium phase diagram and optical absorption properties of ZnXO3 (X = Ge, Sn, and Pb) of LiNbO3 type (LN- ZnXO3) have been calculated by density functional theory. We find that LN-ZnXO3 (X = Ge, Sn, and Pb) do not form a stable chemical potential area with respect to the binary compounds, but could be stabilized under external pressures. The non-equilibrium chemical potential areas in LN-ZnXO3 (X = Ge, Sn, and Pb) are in a sequence of Ge > Sn > Pb. The calculated tendency of transition pressures and binary impurities compound during the synthesis of LN-ZnXO3 (X = Ge, Sn and Pb) are consistent with the experimental results, which are explained by the structure and electronic structure analysis. The calculated optical absorption property indicates that LN-ZnPbO3 could be a good ferroelectric photovoltaic material, while LN-ZnXO3 (X = Ge, Sn) are a good visible light transparent material. The diversity of the feasible transition between VBM and CBM charge with small band gap play important roles in good performance of optical absorption property in LN-ZnPbO3. These inclusions could expand the applications of LN-ZnXO3 (X = Ge, Sn, Pb).