Giant electrocaloric effect in BiFeO3 and La codoped PbZr0.7Ti0.3O3 epitaxial thin films in a broad temperature range

Ferroelectric thin/thick films with large electrocaloric (EC) effect are critical for solid state cooling technologies. Here, large positive EC effects with two EC peaks in a broad temperature range (similar to 100 K) were obtained in 0.95Pb(0.92)La(0.08)(Zr0.70Ti0.30)(0.98)O-3-0.05BiFeO(3) (BFO-La-codoped PZT) epitaxial thin films deposited on the (100), (110) and (111) oriented SrTiO3 (STO) substrates by a sol-gel method. The thin film deposited on the (111) oriented STO substrate exhibited a stronger EC effect (similar to 20.6 K at 1956 kV/cm) near room temperature. However, the thin films deposited on the (100) and (110) oriented STO substrates exhibited a stronger EC effect (similar to 18.8 K at 1852 kV/cm and similar to 20.8 K at 1230 kV/cm, respectively) around the peak of the dielectric permittivity (T-m, similar to 375 K). Particularly, as the direction of the applied electric field was switched (E < 0), the Delta T of the (100)-oriented thin films around T-m was enhanced significantly from 18.8 K to 38.1 K. The self-induced-poling during the preparing process maybe plays a key role on the magic phenomenon. It can be concluded that the BFO-La-codoped PZT epitaxial thin films are promising candidates for application in the next solid-state cooling devices. (C) 2021 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.