Journal of Ceramic Processing Research

Ceramic Processing Research Center (한양대학교 세라믹연구소)
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Structural and electrical properties of K(Ta,Nb)O3 thin film prepared by sol-gel method for electrocaloric devices

  • Min-Su Kwon (Dept. of Materials Engineering and Convergence Technology, RIGET, Gyeongsang National University) ;
  • Ji-Won Kim (Dept. of Materials Engineering and Convergence Technology, RIGET, Gyeongsang National University) ;
  • Joo-Seok Park (Business Cooperation Center, Korea Institute of Ceramic Engineering and Technology) ;
  • Sung-Gap Lee (Dept. of Materials Engineering and Convergence Technology, RIGET, Gyeongsang National University)
  • Received : 2020.06.12
  • Accepted : 2020.10.06
  • Published : 20200000
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Abstract

This study investigated the structural and electrical properties of thin K(Ta0.6Nb0.4)O3 films for their applicability to electrocaloric devices. Both of the sol-gel and spin coating methods were used to fabricate thin films. Those sintered at 650 ℃ showed a KTN phase with pyrochlore of K2Ta2O6, but those sintered at 750 ℃ showed pure polycrystalline phase without a pyrochlore phase. The lattice constants observed were a= 3.990nm. The dielectric constant rapidly decreased due to decrease in polarization of space charge approximately at an applied frequency of 10 kHz. The dielectric constant and loss at 30 ℃ of the thin films sintered at 750 ℃ were 3,617 and 0.264. The dielectric constant of the specimen sintered at 750 ℃ decreased to about -8.27 %/V according to the applied DC field. The remanent polarization and coercive field at 36 ℃ of the specimen sintered at 750 ℃ were 20.0 µC/cm2 and 122.6 kV/cm. When the electric field of 247 kV/cm was applied to the specimen sintered at 750 ℃, the highest electrocaloric property of 3.02 ℃ was obtained.

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Acknowledgement

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2017R1D1A3 B03032164) and by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET) through Agriculture, Food and Rural Affairs Research Center Support Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (717001-7).