Excellent energy storage performance of Nd-modified lead-free AgNbO3 ceramics via triple collaborative optimization

Lead-free Dielectric capacitors that possess high power density as well as swift charging/discharging speed are in tremendous requirement in pulse/high power fields, but the lower recovery energy density and efficiency restrict their applications. Herein, via triple collaborative optimization, we designed Nd-modified AgNbO₃ antiferroelectric ceramics with excellent energy storage performance. First, Nd³⁺ ions are smaller than Ag⁺ ions, which effectively inhibits cation displacements and the tilting of oxygen octahedra, leading to an optimized phase composition, the suppressed ferroelectricity and enhanced antiferroelectricity. Second, the valence of Nd³⁺ ions are higher than that of Ag⁺ ions, which help to lower the content of oxygen vacancies. Third, the random substitution of Nd³⁺, extrinsic ions, cause the chemical disorder, thus dwindling the grain size. Both of the latter could boost the breakdown field. Eventually, the synchronously boosted energy density of 7.16 J/cm³ and efficiency of 72 %, together with excellent frequency stability, temperature tolerance, ultrafast charging/discharging time of 45 ns and superhigh power density of 354.2 MW/cm³, are achieved in Ag_0.91Nd_0.03NbO₃. All these merits manifest Nd- AgNbO₃ as a promising candidate for lead-free high-power energy storage devices. Our work brings forward a good reference for developing the capabilities of antiferroelectric capacitors.