The study of the electronic properties of Bi0.5Na0.5TiO3, Bi0.5Na0.5Ti0.5Zr0.5O3 and Bi0.5Na0.5ZrO3 compounds and comparing their structures

This paper analyzes electronic properties of BNT, BNTZ, and BNZ compounds under the framework of Density Functional Theory (DFT), using the Full Potential method and Linearized Augmented Plane wave (FP-LAPW) and the Generalized Gradient Approximation (GGA). The optimized superlattice of compounds BNT, BNTZ, BNZ are made with lattice constants a = b = 5.5419, c = 7.7526 and a = b = 5.6884, c = 16.0417 and a = b = 5.7583, c = 8.1096 with space group of P4bm, accordingly. Electron density calculated from these two compounds demonstrates that substituting Zr atoms with Ti changes ionic bonding strength of atoms. Moreover, the type of chemical bonding for each atomic determined in the structure separately. Calculating density of states and band structure, while electron configuration energy gaps in compounds BNTZ and BNZ are 1.7eV and 1.45 eV, respectively, the energy gaps of BNT is 1.9 eV. Density of states and band structure also demonstrate that there is a strong hybridization among the atomic orbitals of O, Ti, and Zr close to the Fermi energy.