Improved energy storage and electrocaloric properties of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramic

Abstract

Lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramic powders were synthesized using the sol-gel method. To achieve high-energy storage and large electrocaloric effect in bulk ceramics the ceramics thickness was reduced. Dielectric, ferroelectric, energy storage, and electrocaloric properties were investigated for BCZT ceramic with 400 µm. Here, pure crystalline structure and homogenous microstructure were identified by XRD analysis and SEM measurements, respectively. The dielectric measurements revealed a maximum dielectric constant associated with ferroelectric-paraelectric phase transition. The maximum of εr' was 7841 around 352 K. Furthermore, the BCZT ceramic showed improved energy storage and electrocaloric properties. A high recoverable energy density Wrec of 0.24 J/cm 3 and a total energy density Wtotal of 0.27 J/cm 3 with an efficiency coefficient of ~ 88% at 423 K under an electric field of 55 kV/cm was obtained. Besides, The maximum value of ΔT = 2.32 K, the electrocaloric responsivity ζ = 0.42 K mm/kV, the refrigeration capacity RC= 4.59 J/kg and the coefficient of performance COP = 12.38 were achieved around 384 K under 55 kV/cm. The total energy density Wtotal and the temperature change ΔT were also calculated by exploiting the Landau-Ginzburg-Devonshire (LGD) theory. The theoretical results matched the experimental findings.These results suggest that the synthesized BCZT ceramic with the reduced thickness could be a promising candidate for energy storage and electrocaloric applications.