Influence of substitution with Lead, Zinc, Niobium atoms on the electronic properties of BaTiO₃, as studied by means of ab initio methods.

Calculations were performed without the spin-polarized density functional theory, using the Vienna Ab Initio Symulating Package (VASP). Especially, the A and B-site atom ordering in (1-x)BaTiO₃-xPb(Zn_1/3Nb_2/3)O3 (BT-PZN) and its influence on the bands structure and density of electronic states were explored. The results suggest that atom ordering at A and B sites in BT-PZN significantly affects the results achieved. The tested properties for these system were computed to determine the differences in spectra shape with respect to the band gap. The total (TDOS) and partial (PDOS) densities of states of BT-PZN systems are computed for concentrations x = 0 and 0.125. The results shown that the valence band was formed mainly by oxygen atoms, while the conduction band was determined by the niobium atoms for 0.875BT-0.125PZN and titanium for BT. As the calculations showed, the difference in the energy gap value between BT-PZN and undoped BaTiO₃ (BT) is 0.23 eV and is larger for BT-PZN. It can therefore be concluded that doping BT with Pb, Zn and Nb atoms leads to an increase in band gap. The presented perovskite is expected to be useful as a new low-lead electronic material.