Polarization degradation and oxygen-vacancy rearrangement in Mn-doped BaTiO3 ferroelectrics ceramics

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 center dot center dot]) but also on the majority-acceptor (Mn3+) concentration. Density functional theory (DFT) calculations show that the association of VO center dot center dot with Mn3+ and the following alignment of the defect dipole (VO center dot center dot-Mn3+) along P-s (spontaneous polarization) provide an energetically favorable defect structure due to the lowering in energy of the Mn-3d(z2) electron. It is concluded that the double-hysteresis-like loop (P-E-double) observed with the high concentrations of VO center dot center dot and Mn3+ originates from the reversible switching of a 90 domain structure stabilized by the formation of the VO center dot center dot-Mn3+ // P-s configuration. (C) 2014 The Ceramic Society of Japan. All rights reserved.