Electrocaloric effect in heterolayered potassium tantalate niobate thin films prepared by sol-gel method

Abstract

Heterolayered potassium tantalate niobate(KTN(70/30)/KTN(30/70)) thin films on Pt/Ti/SiO2/Si substrates prepared by the solgel process and spin coating method. When sintered at 700 degrees C or higher, the X-ray diffraction intensities of the perovskite phase were greatly increased, and it was observed as the main phase of the KTN heterolayered thin film. As the sintering temperature increased from 650 degrees C to 800 degrees C, the average grain size increased from 146nm to 380 nm, and the average thickness of the KTN films coated six times was about 394-441 nm. Dielectric constant and dielectric loss of the KTN film sintered at 750 degrees C and room temperature showed good properties of about 2850 and 0.573, respectively, and all films exhibited the typical dielectric relaxation characteristics. The phase transition temperature of KTN thin film was around 12-13 degrees C. Remanent polarization and the coercive field of KTN film sintered at 750 degrees C showed excellent properties of 23.98 mu C/cm(2) and 35.41 kV/cm, respectively. Adiabatic temperature changes (Delta T) and electrocaloric strength of the KTN films sintered at 750 degrees C at 60 degrees C were 2.67 degrees C and 0.012 KcmkV(-1), respectively.