Structural and electrical properties of K(Ta0.62Nb0.38)O3/BiFeO3 multilayer films for electrocaloric devices

Abstract

KTN/BFO multilayer films were manufactured using the spin-coating method on Pt/Ti/SiO2/Si substrate with KTN(62/38) and BFO metal alkoxide solutions. The mean thickness of the multilayer films was about 420-450 nm. A rough interfacial layer was observed at the interface between the lower substrate and the film when sintered at 650oC. Dense microstructures without pores inside of the films were shown via TEM analysis, and an interface between the KTN and BFO layers was clearly observed. The Curie temperature was about 16oC. Dielectric constant and dielectric loss were 1380 and 0.384 at 20oC, respectively. Coercive field of the 2-layer and 6-layer films were 72.6 and 80.4 kV/cm at room temperature, respectively. ΔT and EC coefficient of the 6-layer films sintered at 630oC were 1.96oC and 0.13×10-6 oCmV-1, respectively. © 2022, Hanyang University. All rights reserved.