Tunable temperature range of stress-enhanced electrocaloric effects in composition gradient bilayers

We investigated a tunable temperature range of stress-enhanced electrocaloric effects in composition gradient bilayers by using the phenomenological Landau-Devonshire thermodynamic theory. A tunable temperature range of entropy change was obtained from 265 ∼ 270 K for the specific composition of BaSrTiO₃ bilayers. Theoretical analysis shows that the external stress can tune the temperature range of electrocaloric effects from 220 K to 286 K, and the stress can tune the maximum temperature change 13 K per GPa. The thickness ratio of composition gradient films also can vary the adiabatic temperature change under constant stress. The present study therefore contributes to the understanding of stress effects of electrocaloric cooling and provides guidance for experiments to design high-efficiency cooling devices.