The influence of the electrical boundary condition on domain structures and electrocaloric effect of PbTiO3 nanostructures

The electrocaloric effect (ECE) induced by the domain switching of PbTiO3 (PTO) nanoparticles under the different electrical boundary conditions is carried out using the phase field model. The toroidal moment of polarization with vortex domain structures decreases to zero taking surface charge compensation into the electrical boundary condition, i.e. intermediate electrical boundary. There exists a critical parameter value 0.25, which decides the single domain and vortex domain structures of ferroelectric nanomaterial at the room temperature. The loops of toroidal moment as a function of the applied curled electric filed are obtained under the different electrical boundary conditions. The various domain structures in ferroelectric nanostructure are discussed in detail. Moreover negative and positive adiabatic temperature changes accompanying with vortex domain structure switching are obtained with the curled electric field under the intermediate electrical boundary. These results indicate that ferroelectric nanostructures can be practical used in field of cooling and heating technology through adjusting the surface electrical boundary.