The enhanced electrocaloric effect in P(VDF-TrFE) copolymer with barium strontium titanate nano-fillers synthesized via an effective hydrothermal method

An effective hydrothermal method is developed to synthesize barium strontium titanate (BST) nanoparticles with a mean size below 30 nm, which are used for the fabrication of nanocomposite films consisting of ferroelectric co-polymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and ceramic nanoparticles. The interface between the nanoparticle and the polymeric matrix is found to improve the polarization and pyroelectric behaviors of the nanocomposites, resulting in a much enhanced electrocaloric effect as compared with that of the pristine P(VDF-TrFE). The electrocaloric temperature change is 2.5 degrees C under electric fields of similar to 600 kV cm(-1). The effects of Ba0.75Sr0.25TiO3 nanoparticles on the ferroelectric-to-paraelectric transition of P(VDF-TrFE) are investigated using dynamical mechanical relaxation. The results suggest that the improved electrocaloric effect in the nanocomposites could be related with the localized polarization field near the surfaces of Ba0.75Sr0.25TiO3 nanoparticles.