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As a lead-free material, AgNbO 3 has received a lot of attention for its potential application in the field of energy storage. Herein, Ag x NbO 2.5+ x /2 ceramics were successfully synthesized via solid state reaction with the x ranged from 1 to 0.92. The effect of silver deficiency on structure, dielectric properties and energy storage performance was investigated. As x value decreased from 1 to 0.94, the unit volume of Ag x NbO 2.5+ x /2 ceramics contracted. Meanwhile, all the compositions displayed double hysteresis loops with reduced P max , P r and enhanced transformation fields (E F and E B) as functions of silver deficiency. Silver deficiency stabilized the antiferroelectric state in the FIE (-like) phase and improved the energy storage performance of AgNbO 3 ceramics. Hence, an enhanced energy storage performance (W rec = 3.1 J/cm3, η = 49%) were achieved in Ag 0.94 NbO 2.97 ceramic. [ABSTRACT FROM AUTHOR]

Sodium niobate (NaNbO 3 , NN)-based ferroelectric ceramics have been extensively studied owing to their antiferroelectric (AFE) nature. However, the dielectric properties of NN-based ceramics, which would be beneficial to capacitor devices, gain less research interest. In this study, (1− x)NaNbO 3 - x Bi(Mg 0.5 Ti 0.5)O 3 (NN- x BMT, x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) ferroelectric ceramics were manufactured by a traditional solid state method. Structure and dielectric/ferroelectric properties were studied in detail by X-ray diffraction, dielectric spectrum as well as polarization-electric field hysteresis loops. All ceramic samples show an AFE P phase in the doping range. As x increases, the grain size of studied compositions gradually decreases from 5.36 μm in x = 0 to 2.05 μm in x = 0.05. In addition, the incorporation of BMT plays a regulatory role to the Curie temperature T C of ceramic samples, which decreases almost linearly from 375 °C x = 0 to 216 °C x = 0.05 at a rate of 33 °C/1 at. %. However, the degree of diffusion for each composition does not change significantly. More importantly, ultra-high thermally stable dielectric responses in a wide temperature range are obtained in NN- x BMT. Especially in x = 0.03, its permittivity is around 500 at room temperature and shows a variation less than 4.4% from 30 to 150 °C. Our results may have some guiding significance for the preparation of NN-based ceramics with specific T C , and are significantly important for capacitor applications requiring a wide temperature range stability. [ABSTRACT FROM AUTHOR]