Understanding NaNbO₃-Based Ceramics with Enhanced Antiferroelectricity for High Energy-Storage Density Applications

Lead-free antiferroelectric (AFE) ceramics have attracted increasing attention in recent years for its niche application in high-power capacitors owing to both environmental friendliness and high energy density. NaNbO₃ (NNO) is one of few lead-free perovskites with a AFE structure. But the polarization-electric field (<i>P</i>-<i>E</i>) double hysteresis loop was only observed in high-quality single crystals, while in most cases, it was found to possess a ferroelectric (FE) ordering [1,2]. To enhance the antiferroelectricity in NNO, a composition modification strategy by doping was proposed to stabilize the AFE phase effectively [3]. However, in the case of lead-free NNO-based ceramics, the doping effect on its antiferroelectricity is still very poorly understood. In this work, by using first-principles calculations, we will show that the AFE phase of pure NNO is stabilized in the solid-solution due to the decrease of its tolerance factor. A modification of the relative stability of the polar and nonpolar structures will be rationalized by the phase transition pathways for the switching of polarization with the calculated energy barriers [2]. Here, we attempt to explain the effectively favoring of the nonpolar-to-polar AFE transitions over the polar-to-polar FE domain switching. Through this work, we rationalize and provide an atomic-scale perspective of the AFE-FE phase transition in NNO-based ceramics to further engineer novel lead-free antiferroelectric oxides for energy storage applications.<br/><br/>[1] M.-H. Zhang, H. Ding, S. Egert, C. Zhao, L. Villa, L. Fulanović, P. B. Groszewicz, G. Buntkowsky, H.-J. Kleebe, K. Albe, A. Klein, and J. Koruza, <i>Nat. Commun</i>. <b>14</b>, 1525 (2023).<br/>[2] K. Kim, W. Hwang, J.-H. Lee, and A. Soon, <i>J. Mater. Chem. C</i> <b>10</b>, 10500 (2022).<br/>[3] M.-H. Zhang, N. Hadaeghi, S. Egert, H. Ding, H. Zhang, P. B. Groszewicz, G. Buntkowsky, A. Klein, and J. Koruza, <i>Chem. Mater.</i> <b>33</b>, 266 (2021).