Enhanced electrocaloric effect and energy storage response in lead-free (1-x)K0.5Na0.5NbO3 - xBaTiO3 ferroelectric ceramics

Ferroelectric/antiferroelectric materials are demanded for the development of future eco-friendly high-efficient electrocaloric refrigeration technology and energy-storage devices. Here, we report the electrocaloric effect (ECE) and an energy storage response in lead-free (1-x)K0.5Na0.5NbO3-xBaTiO3 (KNN-xBT) ferroelectric solid solution ceramics with x = 0.04, 0.06, 0.08, and 0.10 synthesized via the traditional solid-state route. The XRD and Raman spectroscopy investigations confirmed the coexistence of orthorhombic and tetragonal phases. The BT substitution has shifted the phase transitions of KNN towards the lower temperature side and also helped to diffuse the phase transitions. The maximum value of the ECE (ΔTmax), electrocaloric responsivity (ΔT/ΔE) and the recoverable energy density (Wrec) were evaluated to be around 0.70 K, 1.75 × 10−7 KmV−1 and 0.22 Jcm−3, respectively in KNN–xBT ceramics for x = 0.08 at an applied electric field of 40 kVcm−1. This study suggested that KNN-xBT material is an attractive ferroelectric material for potential applications in the design of ozone-friendly solid-state freezing technology and energy-storage devices.