Enhancing the energy storage properties of Ca0.5Sr0.5TiO3-based lead-free linear dielectric ceramics with excellent stability through regulating grain boundary defects

Abstract

Dielectric materials with high energy densities and efficiencies are greatly required in the field of power electronics to satisfy demand. This study presents a regulating strategy through Zr⁴⁺ doping and oxygen treatment for reliably enhancing the energy storage performances of Ca_0.5Sr_0.5TiO₃ ceramics. The introduction of Zr⁴⁺ inhibits grain growth, and grain boundary barrier effects are enhanced via oxygen treatment; these outcomes are systemically analyzed using complex impedance data. Exceptional energy storage performance is shown; an energy density of 3.37 J cm⁻³ and 96% energy efficiency under a breakdown strength of 440 kV cm⁻¹ are obtained simultaneously in Ca_0.5Sr_0.5Ti_0.85Zr_0.15O₃ ceramics following oxygen treatment, which are better results than for other reported linear dielectric systems. This system also possesses excellent stability, with minimal fluctuations (<10%) over wide frequency (1–1000 Hz) and temperature (20–120 °C) ranges. Furthermore, pulsed charging and discharging tests are carried out, aimed at evaluating the practical performance of the ceramic materials. A prominent C_D value of 293.3 A cm⁻² and P_D value of 17.6 MW cm⁻³ are achieved, and the stored energy is released sharply (∼20 ns); the ceramics also possess outstanding temperature stability (20–120 °C) and fatigue resistance (300 cycles). These properties verify that these lead-free linear dielectric ceramics have potential for practical energy storage applications, especially in high-temperature and high-pressure environments.