Materials & Design (Sep 2021)
A Bi1/2K1/2TiO3-based ergodic relaxor ceramic for temperature-stable energy storage applications
Abstract
Relaxor ferroelectrics are attractive for the high energy storage density. However, the polarization responses of most relaxor ferroelectrics are sensitive to temperature, thus leading to thermal-dependent energy storage properties. In this work, 0.5Bi1/2K1/2TiO3–0.5SrTiO3 (0.5BKT–0.5ST) and 0.95(0.5Bi1/2K1/2TiO3–0.5SrTiO3)–0.05Bi(Zn1/2Ti1/2)O3 (BKT–ST–0.05BZT) ceramics were prepared using the solid-state reaction method. Both compositions showed an average cubic structure, with a relaxor-type dielectric anomaly. The rather low remanent polarization and delayed saturated polarization indicated the formation of the ergodic polar nano regions. Benefitting from the Bi(Zn1/2Ti1/2)O3 modification, the recoverable energy storage density (Wrec) reached 3.07 J/cm3 because of the enhanced polarization and increased bandgap. Meanwhile, BKT–ST–0.05BZT exhibited a high storage efficiency (η > 88%). When the specimen was heated from 30 °C to 150 °C, Wrec under the maximum electric field Em of 150 kV/cm varied from 1.58 to 1.63 J/cm3 (< ±2%).