Ultrahigh Energy Storage in (Ag,Sm)(Nb,Ta)O3 Ceramics with a Stable Antiferroelectric Phase, Low Domain-Switching Barriers, and a High Breakdown Strength

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 (eta). 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/cm(3), eta of 72.55%, power density of 173.73 MW/cm(3), and quick discharge rate of 18.4 ns, surpassing those of many lead-free ceramics, are obtained in the (Ag0.91Sm0.03)(Nb0.85Ta0.15)O-3 ceramic. Finite element simulations for the breakdown path and transmission electron microscopy measurements of domains verify the rationality of the design strategy.