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Inhomogeneous electric-field–induced negative/positive electrocaloric effects in ferroelectric nanoparticles

The electrocaloric effect in PbTiO3 ferroelectric nanoparticles has been studied using Landau-Ginzburg-Devonshire theory to determine the optimal electric field to induce large adiabatic temperature changes. The calculation results show that a large positive or negative adiabatic temperature change could be induced using an inhomogeneous electric field. The electrically induced negative adiabatic temperature change becomes positive as the strength of the electric field is increased. This transformation of the adiabatic temperature change is attributed to domain switching owing to the applied electric field. These results may provide an explanation for transformations from a negative to a positive electrocaloric effect in ferroelectrics.