Effects of annealing treatment on microstructure, electrical and magnetodielectric properties of BiFe0.98Co0.02O3/Al–doped ZnO layered thin films prepared by chemical solution deposition

Abstract

Multiferroic thin films of BiFe0.98Co0.02O3 (BFCO) were grown on Al2O3 (ALO) substrates having a buffer layer of Al (2%) doped ZnO (ZAO) prepared by using chemical solution deposition (CSD) method. Effect of annealing temperature and annealing atmosphere on the structural, microstructural, dielectric, leakage, transport, magnetic and magnetodielectric (MD) properties of films have been investigated. BFCO/ZAO/ALO films grown under oxygen atmosphere show better crystallinity, smooth surface and slightly larger grain size than that of the films annealed in air. Lower leakage current, higher dielectric constant, lower dielectric loss, lower a.c. conductivity and larger MD and magnetoimpedance (MI) effects have been observed for the film annealed at 550 °C under oxygen atmosphere. In order to verify the state of oxygen vacancies, photoluminescence spectra have been studied. Room temperature magnetic behavior of the BFCO/ZAO/ALO films has been studied by performing magnetization measurements. The effect of magnetic field on the dielectric constant and impedance (MD & MI) have been discussed on the basis of magnetostriction effect and mobility of interfacial charges at grain boundaries and bilayer interface.