First principle study of the B-site doped double perovskite oxides LaMg_0.5M_0.5O₃ (M=Sc, Ti, Zr)

The stable configuration of double perovskite LaMgO₃ was constructed by CASTEP module in Materials Studio. How the B sites doping (Sc³⁺, Ti⁴⁺, Zr⁴⁺) affect the structure and physical properties was theoretical investigated. Three configurations of doping are structural geometry and energy optimized by GGA+WC correlation function, according to the principle of minimum energy, the most stable geometry structure is obtained, based on this structure, the physical properties are calculated. The results show that: The energy of LaMg_0.5Ti_0.5O₃ is the lowest and it is deduced as semiconductor according to the band gap. In the vicinity of Fermi level, the interaction between p-electron and d-electron is obvious, which contributes the most to the density of states. By optical properties simulation, the frequency of absorption peaks of the three materials becomes lower and lower in low frequency range, while the absorption peaks of LaMg_0.5Sc_0.5O₃ and LaMg_0.5Zr_0.5O₃ appear earlier than LaMg_0.5Ti_0.5O₃ in high frequency range, but the peak intensity is lower.