Ultrahigh room temperature electrocaloric response in lead-free bulk ceramics via tape casting

Abstract

Solid-state cooling technology based on the electrocaloric effect is attracting increasing attention as an important alternative to traditional cooling systems in microelectronic and integrated electronics. Lead-free bulk ceramics are considered as one of the promising candidates for middle and large-scale electrocaloric cooling because of their environment-friendliness and large heat absorption capacity. However, the room temperature adiabatic temperature change (ΔT) in lead-free bulk ceramics has long been limited by their relatively low dielectric breakdown strength (E_b < 60 kV cm⁻¹), hindering their practical applications. In this work, we propose to use the tape casting technique as a practicable strategy to enhance the densification and decrease the porosity of lead-free bulk ceramics for achieving a high E_b and a large room temperature ΔT. An ultrahigh room temperature ΔT (1.6 K) was realized in a (Ba_0.95Ca_0.05)(Ti_0.94Sn_0.06)O₃ (BCTS) bulk ceramic prepared by the tape casting technique, which is 4 times larger than that of the lead-free bulk ceramics with a similar composition prepared by the conventional ceramic preparing approach. More significantly, unlike the other previously reported results, which only show high ΔT in an extremely narrow temperature range, ΔT of the BCTS bulk ceramic increases from 1.6 K to 2.0 K in the temperature range from 300 K to 345 K, which is comparable with that found in the lead-based bulk counterpart. Most importantly, this work opens up a new avenue to explore lead-free bulk ceramics with a large room temperature ΔT for solid-state refrigeration.