High energy density of Sm-doped Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3 relaxor ferroelectric ceramics

Abstract

Dielectric ceramics have garnered significant attention in the realm of pulsed power system applications. Nevertheless, achieving a high recoverable energy density (W_rec) in dielectric ceramics remains challenging. Here, a high W_rec of 6.1 J cm⁻³ was achieved in (1 − x)(0.6Na_0.5Bi_0.5TiO₃–0.4Sr_0.7Bi_0.2TiO₃)–xSm₂O₃ relaxor ferroelectric ceramics (RFCs). The enhanced W_rec stems from two factors: (I) the incorporation of Sm³⁺ with a small ionic radius can increase disorder at the A-site, thereby enhancing relaxor properties and reducing remnant polarization (P_r); (II) the introduction of Sm₂O₃ reducing vacancy and grain size, leading to an enhanced breakdown strength (E_b) of 470 kV cm⁻¹. This higher E_b facilitates increased maximum polarization (P_max). The increased E_b and the large polarization difference (ΔP = P_max − P_r) contribute to a substantial improvement in W_rec. Additionally, a novel approach was introduced to assess the relaxor characteristics by quantifying the degree of linear fitting of P–E loops. This study presents an effective strategy for designing high W_rec dielectric ceramics and introduces an innovative method for analyzing the relaxor properties of RFCs.