Thermally-stable high energy storage performances and large electrocaloric effect over a broad temperature span in lead-free BCZT ceramic

Abstract

Ba_0.85Ca_0.15Zr_0.10Ti_0.90O₃ (BCZT) relaxor ferroelectric ceramics exhibit enhanced energy storage and electrocaloric performances due to their excellent dielectric and ferroelectric properties. In this study, the temperature-dependence of the structural and dielectric properties, as well as the field and temperature-dependence of the energy storage and the electrocaloric properties in BCZT ceramics elaborated at low-temperature hydrothermal processing are investigated. X-ray diffraction and Raman spectroscopy results confirmed the ferroelectric-paraelectric phase transition in the BCZT ceramic. At room temperature and 1 kHz, the dielectric constant and dielectric loss reached 5000 and 0.029, respectively. The BCZT ceramic showed a large recovered energy density (<i>W</i> _rec) of 414.1 mJ cm^-3 at 380 K, with an energy efficiency of 78.6%, and high thermal-stability of <i>W</i> _rec of 3.9% in the temperature range of 340-400 K. The electrocaloric effect in BCZT was explored <i>via</i> an indirect approach following the Maxwell relation at 60 kV cm^-1. The significant electrocaloric temperature change of 1.479 K at 367 K, a broad temperature span of 87 K, an enhanced refrigerant capacity of 140.33 J kg^-1, and a high coefficient of performance of 6.12 obtained at 60 kV cm^-1 make BCZT ceramics potentially useful coolant materials in the development of future eco-friendly solid-state refrigeration technology.