A ferroelectric polarization contribution from defect dipoles in acceptor Aurivillius oxide, (Na,Bi)_0.47(Li,Ce)_0.03Bi ₂Ta_1.97Sc_0.03O_8.97

Double-loop-like characteristic was detected in acceptor Aurivillius ceramic, (Na,Bi)_0.47(Li,Ce)_0.03Bi₂Ta _1.97Sc_0.03O_8.97 (NBTO-LiCeSc-0.03) due to the restoring force provided by defect polarization (P_D). The P _D was associated with non-centric distributing defect dipoles [(Sc_Ta″-V_O^••) ^×], which was verified by impedance spectroscopy measures. Interestingly, the P_D could be reoriented with high external electric field at very low frequency, which contributed to the significant enhancement of the polarization of NBTO-LiCeSc-0.03. Air or O₂ annealing led to the degradation of the polarization owing to high leakage current and the strong "pinning" effects of space charge and charged defect complexes [e.g., (Sc_Ta″-O_O^•)′].