Thermal-stability of the enhanced piezoelectric, energy storage and electrocaloric properties of a lead-free BCZT ceramic

Abstract

The lead-free Ba_0.85Ca_0.15Zr_0.10Ti_0.90O₃ (BCZT) relaxor ferroelectric ceramic has aroused much attention due to its enhanced piezoelectric, energy storage and electrocaloric properties. In this study, the BCZT ceramic was elaborated by the solid-state reaction route, and the temperature-dependence of the structural, electrical, piezoelectric, energy storage and electrocaloric properties was investigated. X-ray diffraction analysis revealed a pure perovskite phase, and the temperature-dependence of Raman spectroscopy, dielectric and ferroelectric measurements revealed the phase transitions in the BCZT ceramic. At room temperature, the strain and the large-signal piezoelectric coefficient reached a maximum of 0.062% and 234 pm V^-1, respectively. Furthermore, enhanced recovered energy density (<i>W</i> _rec = 62 mJ cm^-3) and high-energy storage efficiency (<i>η</i>) of 72.9% at 130 °C were found. The BCZT ceramic demonstrated excellent thermal stability of the energy storage variation (ESV), less than ±5.5% in the temperature range of 30-100 °C compared to other lead-free ceramics. The electrocaloric response in the BCZT ceramic was explored <i>via</i> the indirect approach by using the Maxwell relation. Significant electrocaloric temperature change (Δ<i>T</i>) of 0.57 K over a broad temperature span (<i>T</i> _span = 70 °C) and enhanced coefficient of performance (COP = 11) were obtained under 25 kV cm^-1. The obtained results make the BCZT ceramic a suitable eco-friendly material for energy storage and solid-state electrocaloric cooling devices.