Strategy for stabilization of the antiferroelectric phase (Pbma) over the metastable ferroelectric phase (P2₁ma) to establish double loop hysteresis in lead-free (1-x)NaNbO_3-x SrZrO₃ solid solution

A new lead-free antiferroelectric solid solution system, (1-x)NaNbO₃-xSrZrO₃, was rationalized through noting the crystal chemistry trend, of decreasing the tolerance factor and an increase in the average electronegativity of the system. The SrZrO₃ doping was found to effectively stabilize the antiferroelectric (P) phase in NaNbO₃ without changing its crystal symmetry. Preliminary electron diffraction and polarization measurements were presented which verified the enhanced antiferroelectricity. In view of our recent report of another lead-free antiferroelectric system (1-x)NaNbO₃-xCaZrO₃ [H. Shimizu et al. "Lead-free antiferroelectric: xCaZrO₃ - (1-x)NaNbO₃ system (0 ≤ x ≤ 0.10)," Dalton Trans. (published online)], the present results point to a general strategy of utilizing tolerance factor to develop a broad family of new lead-free antiferroelectrics with double polarization hysteresis loops. We also speculate on a broad family of possible solid solutions that could be identified and tested for this important type of dielectric.