Enhanced electrocaloric effect in BaSn/TiO₃ ceramics by addition of CuO

For several decades, ferroelectrics with enhanced electrocaloric (EC) effect have served as competitive alternatives for solid-state cooling devices. In order to enhance the EC effect, there has been increasing research interest on exploring novel systems of EC materials and efficient cooling cycles. In contrast, optimizing intrinsic properties through doping effect has been relatively ignored. In this work, we introduce the binary compound CuO as an additive into the conventional lead-free BaSn_0·11Ti_0·89O₃ (BST) ferroelectric ceramic. This leads to a remarkably large adiabatic temperature change of ΔT = −0.33 °C under a relatively low electric field (10 kV/cm). This is higher than the ΔT of pure BST (ΔT = −0.15 °C, under 10 kV/cm). The largest of ΔT = −0.48 °C was achieved under 20 kV/cm. We assume that the large temperature change was achieved due to the addition of CuO additive, which improves the ferroelectric properties (e.g., a higher polarization and a lower coercive field). In addition, by introducing CuO additives, the breakdown electric field of the ceramics was also enhanced at high temperatures (above the Curie temperature, T_C) and the working temperature range was greatly broadened (30 °C–60 °C) under a slightly high electric field. Our findings present a promising approach to enhance the EC effect by tuning the intrinsic properties of EC materials. We expect that our work emphasizes the importance of additives in enhancing the EC properties.