Large electrocaloric effect and energy storage performance of site-engineered lead-free Ba_1-x(Bi_0.5Li_0.5)_xTiO₃ferroelectric oxides

Environment-friendly solid-state cooling technology necessitates the search for energy-efficient electrocaloric (EC) materials. In this regard, the EC effect and energy storage performance have been investigated on a site-engineered lead-free Ba1-x(Bi0.5Li0.5)xTiO3 (x = 0.0, 0.10, 0.125, 0.15 and 0.175) system from the perspective of its enhanced characteristic parameters. The ferroelectric and dielectric studies reveal the tunable polarization and Curie temperature as a function of composition. The EC measurements on these samples display superior EC parameters compared to the values reported for other polycrystalline ferroelectric systems. The observed EC parameters for the x = 0.10 sample, such as the change in entropy (ΔS), adiabatic temperature change (ΔT) and EC coefficient are 2.63 J kg-1 K, 2.03 K and 0.68 K mm-1 kV, respectively. Notably, the x = 0.15 sample displays near room-temperature (307 K) EC response with ΔT ≥ 0.30 K over a broad 24 K temperature range. In addition, the energy storage performance studies elucidate that the Ba1-x(Bi0.5Li0.5)xTiO3 compound with x = 0.175 displays large energy storage efficiency (96.7%) with 144 mJ cm-3 as the storage density. The tunable EC characteristics and high energy storage efficiency demonstrated in this work illustrate the application potential of site-engineered BaTiO3 samples in efficient cooling and storage devices.