Ultrahigh Energy Storage in (Ag,Sm)(Nb,Ta)O₃ Ceramics with a Stable Antiferroelectric Phase, Low Domain-Switching...

AgNbO₃ (AN) antiferroelectrics (AFEs) are regarded as a promising candidate for high-property dielectric capacitors on account of their high maximum polarization, double polarization-electric field (P-E) loop characteristics, and environmental friendliness. However, high remnant polarization (P_r) and large polarization hysteresis loss from room-temperature ferrielectric behavior of AN and low breakdown strength (E_b) cause small recoverable energy density (W_rec) and efficiency (η). To solve these issues, herein, we have designed Sm³⁺ and Ta⁵⁺ co-doped AgNbO₃. The addition of Sm³⁺ and Ta⁵⁺ reduces the tolerance factor, polarizability of B-site cations, and domain-switching barriers, enhancing AFE phase stability and decreasing hysteresis loss. Meanwhile, adding Sm³⁺ and Ta⁵⁺ leads to decreased grain sizes, increased band gap, and reduced leakage current, all contributing to increased E_b. As a benefit from the above synergistic effects, a high W_rec of 7.24 J/cm³, η of 72.55%, power density of 173.73 MW/cm³, and quick discharge rate of 18.4 ns, surpassing those of many lead-free ceramics, are obtained in the (Ag_0.91Sm_0.03)(Nb_0.85Ta_0.15)O₃ ceramic. Finite element simulations for the breakdown path and transmission electron microscopy measurements of domains verify the rationality of the design strategy.