Structural and Electrical Properties of K(Ta,Nb)O3 Thin Films for the Application of Electrocaloric Devices

Abstract

In this study, K(Ta0.6Nb0.4)O3 thin films were fabricated by sol–gel method and their structural and electrical properties were measured to investigate the applicability for electrocaloric devices. As the thickness of thin films increased, crystallinity was improved. The average thickness of the thin films with a single coating was about 130–140 nm. Dielectric constant, dielectric loss, remanent polarization, and coercive field of the 6 times coated thin KTN films at 30 °C were 4920, 0.492, 18.49 μC/cm2 and 54.7 kV/cm, respectively. As the number of coatings increased, the temperature at which the decrease in remanent polarization began also subsided. Likewise, the rate of change in remanent polarization increased as the temperature became higher. When a voltage of 220 kV/cm was applied to the 3 times coated KTN films, the electrocaloric property was 2.95 °C. When the 3 times coated thin KTN films were at 75 °C, electrocaloric property for a unit electric field was about 1.47 °C.