Excellent Energy-Storage Performance of (0.85 – x)NaNbO3–xNaSbO3–0.15(Na0.5La0.5)TiO3 Antiferroelectric Ceramics through B-Site Sb5+ Driven Phase Transition

NaNbO3-based relaxor antiferroelectric (AFE) ceramics are receiving more and more attention for high power pulse applications. A commonly used design strategy is to add complex perovskites with lower tolerance factors. Herein, a new lead-free AFE system of (0.85 - x)NaNbO3-xNaSbO3-0.15(Na0.5La0.5)TiO3 was specially designed considering the substitution of Sb5+ for Nb5+ reduces the polarizability of B-site ions but increases the tolerance factor. The formation of nanodomains with stable AFE orthorhombic R phase symmetry contributes to a slim and double-like polarization-field hysteresis loop, while the increased resistivity and activation energy as a result of sintering aids lead to an enhanced breakdown strength. Therefore, an excellent energy density Wrec ≈ 6.05 J/cm3, a high energy efficiency η ≈ 80.5%, and good charge-discharge performances (power density PD ≈ 155 MW/cm3 and discharging rate t0.9 ≈ 44.6 ns) were achieved in MnO2-doped x = 0.03 ceramics. The experimental results demonstrate that the B-site Sb5+ driven orthorhombic P-R phase transition and increased local structure disorder should provide a new strategy to design high-performance NaNbO3-based relaxor AFE capacitors.