Mechanism of enhanced relaxor ability and high intrinsic electric field of NaNbO3-based antiferroelectric ceramics based on defect engineering design

With the deepening of the research on energy storage ceramics, more and more matrix systems and modification methods have been reported. A large number of modification methods focus on improving the breakdown electric field, saturated polarization (P-max) or doping with linear materials to obtain high energy storage efficiency (eta) of ceramics. In this work, we choose to increase the weak polar phase on the basis of stabilizing the antiferroelectric (AFE) phase in ceramics, in order to increase the generation of weak coupling polar phase. The ceramic can obtain high polarization while enhancing its relaxor ability and reducing the remanent polarization (P-r). At the same time, the concentration of oxygen vacancies in ceramics is regulated by the change of valence of Fe element during high temperature sintering. It obtains a high ion transition barrier and grain boundary density, so that the ceramics can achieve a high polarization difference (Delta P) under a high intrinsic breakdown electric field and increase the energy storage density (W-rec). In order to analyze the mechanism of energy storage characteristics such as high Delta P and high intrinsic breakdown electric field of ceramics, Sr(Fe0.5Nb0.5)O-3 was introduced into NaNbO3 ceramic, and the (1 - x)NN-xSFN ceramics were prepared and characterized. Finally, the W-rec of 6.24 J/cm(3) and the eta of 85 % were obtained by 0.83NN-0.17SFN ceramics under 570 kV/cm.