High temperature lead-free BNT-based ceramics with stable energy storage and dielectric properties

High-temperature dielectric ceramics are in urgent demand due to the rapid development of numerous emerging applications. However, producing dielectric ceramics with favorable temperature, frequency and electric field stability is still a huge challenge. The construction of multi-phase coexistence material systems is an effective way to obtain stable dielectric and energy storage properties. In this work, NaNbO3 (NN) modified 0.95Bi(0.5)Na(0.5)TiO(3)-0.05SrZrO(3) (BNTSZ) ceramics ((1 - x)BNTSZ-xNN) are designed to achieve the coexistence of rhombohedral and tetragonal phases. The variation in the dielectric permittivity of the 0.8BNTSZ-0.2NN ceramic is less than +/- 15% over the temperature range from -55 degrees C to 545 degrees C, which is the reported record-high upper operating temperature, with a high room-temperature dielectric permittivity of 1170. The 0.8BNTSZ-0.2NN ceramic exhibits excellent frequency and electric field stability as well. Additionally, a large discharge energy density of 3.14 J cm(-3) is obtained in the 0.85BNTSZ-0.15NN ceramic with an energy efficiency of 79% at a high temperature of 120 degrees C under 230 kV cm(-1), with the variation in the discharge energy density being less than +/- 4% in the temperature range from 25 degrees C to 180 degrees C under 120 kV cm(-1). All these features demonstrate that the (1 - x)BNTSZ-xNN ceramics are promising candidates for use at extremely high temperature in both dielectric and energy storage capacitor applications.