Strain‐mediated electrical and optical properties of novel lead‐free CuFe2O4–KNbO3 nanocomposite solid solutions: A combined experimental and Density Functional Theory studies

Abstract

This article summarizes the strain-mediated electrical and optical properties of novel lead-free xCuFe2 O4 (1-x) KNbO3 (x= 0.2, 0.3, and 0.4) multiferroic nanocomposite through a solid state route. X-ray diffraction analysis divulges the influence of interfacial strain in the KNbO3 -CuFe2 O4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. Morphological analysis reveals that the average particle size of 0.3CuFe2 O4 -0.7KNbO3 is 25 nm which is smaller than the other two nanocomposites. The UV-visible absorption studies and Raman spectroscopy of 0.3CuFe2 O4 -0.7KNbO3 nanocomposite present the high energy bandgap and electro coupling of KNbO3 and CuFe2 O4 phases. The DFT theoretical bandgap behaviors of all the three nanocomposites synchronize with the experimental bandgap results. Dielectric, ferroelectric and magnetoelectric behaviors are also improved in 0.3CuFe2 O4 -0.7KNbO3 nanocomposite as compared to pristine KNbO3 and the other two nanocomposites. HIGHLIGHTS: This article summarizes the strain-mediated electrical and optical properties of novel lead-free xCuFe2 O4 -(1-x) KNbO3 (x=0.2, 0.3, and 0.4) multiferroic nanocomposite through a solid state route. X-ray diffraction analysis divulges the influence of interfacial strain in the KNbO3 -CuFe2 O4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. The 0.3CuFe2 O4 -0.7 KNbO3 nanocomposite shows a remarkable increase in the optical bandgap, remnant polarization, dielectric permittivity, and magnetoelectric coefficient compared to the other two nanocomposites. DFT calculations on KNbO3 -CuFe2 O4 matrix reveal the impact of diffusion between two phases and support the bandgap experimental results.