Enhancement of electrocaloric response and elevated energy-storage characteristics in lead-free BCTZ-ZN ceramics

Recently, considerable focus has been on exploring the electrocaloric effect in environmentally friendly, lead-free ferroelectric materials. In this study, lead-free (Ba_0.95Ca_0.05)(Ti_0.95Zr_0.05)_1-<i>x</i> (Zn_1/3Nb_2/3) _<i>x</i> O₃ (BCTZ-<i>x</i>ZN) ceramics were investigated. X-ray diffraction (XRD) analysis confirmed the formation of a pure perovskite structure with a structural phase transition depending on ZN substitution. Dielectric measurements revealed a diffuse phase transition and a shift in Curie temperature with increasing <i>x</i>. The electrical energy storage density (<i>W</i> _rec) was found to be 150 mJ cm^-3 with an efficiency of <i>η</i> = 83% for BCTZ-2.5ZN. At an electric field strength of 25 kV cm^-1, a peak electrocaloric response of 0.68 K at 340 K was attained, with a corresponding electrocaloric responsivity of 0.27 K mm kV^-1 observed at 340 K for BCTZ-2.5ZN. The electrocaloric effect, combined with a calculated coefficient of performance (COP) of 2, demonstrates the material's potential for both cooling and energy storage. These findings underscore BCTZ-<i>x</i>ZN as a promising material for applications in cooling systems and energy storage for electronic devices, offering versatile properties conducive to cooling operations <i>via</i> an external electric field across various operating temperatures.