Ab initio study of doping mechanisms in BaTiO3-BiYO3

A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_Ba, Y_Ti) in BaTiO₃-BiYO₃. Single Bi_Ba and Y_Ti impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed [YO₆] octahedral in single Y impurity. However, in the co-doped Bi_Ba and Y_Ti structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti⁴⁺ difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO₃ ceramic matrix.