  Ferroelectric perovskite oxides possess a large electrocaloric (EC) effect,
but usually at high temperatures near the ferroelectric/paraelectric phase
transition temperature, which limits their potential application as
next-generation solid-state cooling devices. We use classical molecular
dynamics to study the electric field induced phase transitions and EC effect in
PMN-PT (PbMg1/3Nb2/3O3-PbTiO3). We find that the maximum EC strength of PMN-PT
occurs within the morphotropic phase boundary (MPB) region at 300 K. The large
adiabatic temperature change is caused by easy rotation of polarization within
the MPB region.
