Configuration-entropy effects on BiFeO3–BaTiO3 relaxor ferroelectric ceramics for high-density energy storage

Abstract

High energy-storage capability and electric breakdown strength are critical elements in next-generation pulse-power dielectric capacitors. In this report, perovskite (Bi_0.7Ba_0.3)_1−xNa_x(Fe_0.7Ti_0.3)_1−xTa_xO₃ relaxor ferroelectric ceramics (x = 0–0.3) were tailored in terms of configuration entropy from a medium entropy of 1.21R to a high entropy of 2.07R to improve energy storage. The integration of paraelectric NaTaO₃ into BiFeO₃–BaTiO₃ results in breaking of the long-range order and formation of multiple lattice distortions toward relaxor ferroelectric characteristics. Excellent recoverable energy densities of 9.6 J cm⁻³ and 10.3 J cm⁻³ with efficiencies of 77% and 68% at 350 kV cm⁻¹ and 550 kV cm⁻¹ (at 10 Hz) were achieved for x = 0.15 and 0.20, respectively. Wide operating frequency (1–100 Hz) and temperature (25 °C–150 °C) stabilities were confirmed at 300 kV cm⁻¹. Grain boundaries and nanoclusters play critical roles as electric barriers to suppress charge mobility and increase electric breakdown strength. This study presents a promising scheme to utilize high-configuration entropy BiFeO₃–BaTiO₃-based ceramics for high energy-density electrostatic capacitors.