Polarization degradation and oxygen-vacancy rearrangement in Mn-doped BaTiO<sub>3</sub> ferroelectrics ceramics

Abstract

Effects of defect structures on polarization hysteresis properties have been investigated for Mn-doped BaTiO3 ceramics. The polarization hysteresis loops are found to strongly depend not only on the oxygen vacancy concentration ([VO••]) but also on the majority-acceptor (Mn3+) concentration. Density functional theory (DFT) calculations show that the association of VO•• with Mn3+ and the following alignment of the defect dipole (VO••–Mn3+) along Ps (spontaneous polarization) provide an energetically favorable defect structure due to the lowering in energy of the Mn-3dz2 electron. It is concluded that the double-hysteresis-like loop (P-Edouble) observed with the high concentrations of VO•• and Mn3+ originates from the reversible switching of a 90° domain structure stabilized by the formation of the VO••–Mn3+ // Ps configuration.