Structural and electrical properties of Ba(Sr,Ti)O-3/K(Ta,Nb)O-3 multilayer thin film for the application of electro-caloric devices

Abstract

In this study, the multilayered thin films of (Ba,Sr)TiO3/K(Ta,Nb)O-3 were fabricated by the sol-gel and spin coating methods, and their structural and electrical properties were investigated. The specimen showed polycrystalline X-ray diffraction (XRD) characteristics with a tetragonal structure. The average grain size and film thickness for one coating were about 30 similar to 40nm and 60nm, respectively. The phase transition temperature of specimen was lower than 10 degrees C. The dielectric constant and loss at 20 degrees C of the specimen coated six times were 1,231 and 0.69, respectively. The rate of change in dielectric constant at an applied direct current (DC) voltage of the six times coated thin films was 17.3%/V. The electrocaloric effect was the highest around the temperature at which the remanent polarization rapidly changed. When an electric field of 660kV/cm was applied to the triply coated thin films, the highest electrocaloric property of 4.41 degrees C was observed.