Design of Lead-Free Antiferroelectric (1 − x)NaNbO3−xSrSnO3 Compositions Guided by First-Principles Calculations

Antiferroelectric materials exhibit a unique electricfield- induced phase transition, which enables their use in energy storage, electrocaloric cooling, and nonvolatile memory applications. However, in many prototype antiferroelectrics this transition is irreversible, which prevents their implementation. In this work, we demonstrate a general approach to promote the reversibility of this phase transition by targeted modification of the material’s local structure. A new NaNbO3-based composition, namely (1− x)NaNbO3−xSrSnO3, was designed with a combination of firstprinciples calculations and experimental characterization. Our theoretical study predicts stabilization of the antiferroelectric state over the ferroelectric state with an energy difference of 1.4 meV/f.u. when 6.25 mol % of SrSnO3 is incorporated into NaNbO3. A series of samples was prepared using solid-state reactions, and the structural changes upon SrSnO3 incorporation were investigated using X-ray diffraction and 23Na solid-state nuclear magnetic resonance spectroscopy. The results revealed an increase in the unit cell volume and a more disordered, yet less distorted local Na environment, which were related to the stabilization of the antiferroelectric order. The SrSnO3-modified compositions exhibited well-defined double polarization loops and an eight times higher energy storage density as compared to unmodified NaNbO3. Our results indicate that this first-principles calculations based approach is of great potential for the design of new antiferroelectric compositions