A giant electrocaloric effect of a Pb0.97La0.02(Zr0.75Sn0.18Ti0.07)O3 antiferroelectric thick film at room temperature

Abstract

A 2 μm-Pb_0.97La_0.02(Zr_0.75Sn_0.18Ti_0.07)O₃ (PLZST) antiferroelectric (AFE) thick film with tetragonal structure was deposited on LaNiO₃/Si (100) substrates via a sol–gel technique. The electrocaloric effect (ECE) of the PLZST thick film was investigated under the influences of an external electric field and temperature. Giant ECEs (ΔT = 53.8 °C and ΔS = 63.9 J K⁻¹ kg⁻¹) were achieved at 5 °C, which was attributed to a field-induced AFE to ferroelectric (FE) phase transition. Moreover, a large ΔT of above 30 °C was observed in the temperature range of 5 °C to 25 °C. The maximum electrocaloric coefficient (ξ_max = 0.060 K cm kV⁻¹) and refrigeration efficiency (COP = 18) of the film were also obtained at 5 °C. At room temperature, the values of ΔT, ΔS, COP and ξ_max were 35.0 °C, 39.0 J K⁻¹ kg⁻¹, 14 and 0.039 K cm kV⁻¹ at 900 kV cm⁻¹, respectively. The AFE thick films with giant ECEs are promising candidates for applications in cooling systems at room temperature.