Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramic with large energy density and high efficiency under a moderate electric field

Abstract

Lead-free relaxor ferroelectric ceramics of (1 − x)(0.6Bi_0.5Na_0.5TiO₃–0.4Sr_0.7Bi_0.2TiO₃)–xAgNbO₃ were fabricated by a conventional mixed oxide route. The multifunction of AgNbO₃ (AN) doping into the 0.6Bi_0.5Na_0.5TiO₃–0.4Sr_0.7Bi_0.2TiO₃ (BNT–SBT) matrix can be divided into two main aspects. First, it enhances the breakdown electric field (E_b) as a result of reduced grain size and increased resistivity. Second, it improves η via enhancing the relaxation behavior and stabilizing the antiferroelectric (AFE) phase. Eventually, we achieved a large W_rec of 3.62 J cm⁻³ and a high η of 89% simultaneously under a moderate electric field of 246 kV cm⁻¹ as the doping ratio x of AgNbO₃ equals 0.05. In addition, the same sample also exhibits excellent temperature stability and good frequency stability, suggesting that AgNbO₃ doped BNT–SBT ceramics could be an ideal candidate in high energy storage capacitors.