The effect of B-site acceptor doping on the microstructure and electric properties of NaNbO 3 ceramics

Enhancement of the antiferroelectric phase and exhibition of a double P–E hysteresis loop of NaNbO 3 (NN) has been a hot research topic in recent years. In this work, polycrystalline ceramic Na (Nb 0.99 M 0.01 ) O 2.995 (M = Si, Sn and Hf) was successfully prepared by solid-state reaction method. The “pinning” effect of oxygen vacancy and defect dipole in samples obviously influence the performance of microstructure and electric properties. doule-like P–E loop can be found in NN-Sn at room temperature, this characteristic is the interaction of oxygen vacancy with domain walls and the defect polarization of defect dipole. More A-site defects exist in NN-Si and NN-Sn which make domain wall motion easier, and square P–E loops can appear at room temperature. The breakdown strength of NN-Hf is improved, because Hf 4+ doping raises the energy barrier of AFE → FE. So the square P–E loop doesn’t appear in NN-Hf before breakdown at room temperature. The antiferroelectric phase is more easily induced in NN at high temperature, and double P–E loops appear in all samples at 120 °C.