Strain-mediated electrical and optical properties of novel lead-free CuFe 2 O 4 -KNbO 3 nanocomposite solid solutions: A combined experimental and Density Functional Theory studies.

This article summarizes the strain-mediated electrical and optical properties of novel lead-free xCuFe 2 O 4 (1 - x) KNbO 3 (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 KNbO 3 -CuFe 2 O 4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. Morphological analysis reveals that the average particle size of 0.3CuFe 2 O 4 -0.7KNbO 3 is 25 nm which is smaller than the other two nanocomposites. The UV-visible absorption studies and Raman spectroscopy of 0.3CuFe 2 O 4 -0.7KNbO 3 nanocomposite present the high energy bandgap and electro coupling of KNbO 3 and CuFe 2 O 4 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 0.3CuFe 2 O 4 -0.7KNbO 3 nanocomposite as compared to pristine KNbO 3 and the other two nanocomposites. HIGHLIGHTS: This article summarizes the strain-mediated electrical and optical properties of novel lead-free xCuFe 2 O 4 -(1 - x) KNbO 3 (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 KNbO 3 -CuFe 2 O 4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. The 0.3CuFe 2 O 4 -0.7 KNbO 3 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 KNbO 3 -CuFe 2 O 4 matrix reveal the impact of diffusion between two phases and support the bandgap experimental results.