Electrocaloric effect of K(Ta,Nb)O3/BaTiO3 multilayer thin films prepared by sol-gel method

Abstract

KTN/BT multilayer films were fabricated using the sol-gel method and the spin coating method. The average thickness of thesingle-coated film was about 62 to 67 nm and the average grain size was about 92 to 95 nm. TEM analysis made it possibleto observe a clear image difference between the KTN layer and BT layer due to the difference in composition and crystalstructure. As the number of coatings increased, the dielectric constant increased and the Curie temperature increased. The6-layer KTN/BT multilayer film exhibited the highest dielectric constant of about 2530 at a transition temperature of 26 °C. The 6-layer KTN/BT multilayer films showed a remanent polarization and a coercive field of 9.2 μC/cm2 and 91 kV/cm,respectively, at around room temperature. The ΔT and ΔT/ΔE of the 5-layer KTN/BT multilayer film with an applied electricfield of 150 kV/cm were 0.72 K and 4.8 mK·cm/kV, respectively, at around room temperature.