Unveiling the role of chemical pressure on antiferroelectricity in NaNbO₃-based antiferroelectric ceramics

Chemical pressure is widely applied to antiferroelectrics (AFEs) as a criterion to enhance their antiferroelectricity. However, NaNbO3 (NN)-based ceramic with well-defined double polarization hysteresis (P-E) loops was rarely reported based on this strategy, and the effect of chemical pressure on antiferroelectricity remains to be understood. In this work, the Me cations (Me is Ti, Sn, Zr) with different ionic radii were introduced into the component system 0.76NaNbO(3)-0.20AgNbO(3)-0.04CaMeO(3) to tune the negative chemical pressure and investigate its effect on antiferroelectricity. The enhancement of negative chemical pressure can effectively stabilize the AFE phase and reduce hysteresis, as revealed by the P-E loops and dielectric properties, which is further confirmed by the change in crystal lattice parameters and in situ Raman spectra. Rietveld refinement of x-ray powder diffraction reveals that the enhanced negative chemical pressure mainly reduces the cation off-centering displacement and [BO6] octahedral tilting angles. As a result, the 0.76NaNbO(3)-0.20AgNbO(3)-0.04CaZrO(3) exhibits good reversibility of the electric field-induced antiferroelectric-ferroelectric phase transition and well-defined double P-E loops. This work reveals the underlying mechanism of chemical pressure and provides an effective way of discovering new NN-based AFEs.