Cu2+substituted NiFe2O4 thin films via spray pyrolysis technique and their high-frequency devices application

In the present work, Ni1-xCuxFe2O4 thin films were fabricated with compositions of a wide range (0.0 <= x <= 1.0 in the steps of 0.2) using the spray pyrolysis technique. The prepared thin films were analyzed by using X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electronic microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), contact angle, UV-evisible photo spectrometer (UV) and vibrating sample magnetometer (VSM). XRD analysis show, that all thin films possess cubic spinel structure with Fd (3) over bar m space group. The lattice parameter increased from 8.334 to 8.416 angstrom with increase in Cu2+ content obeying Vegard's law. The average crystallite size was found in the range of 10-21 nm. The formation of spinel ferrite phase is confirmed through active Raman mode of A(1g) + E-g + 3T(2g) bands in all thin films using Raman spectroscopy. The grain size obtained from FE-SEM analysis was in the range of 16-26 nm. Using AFM images the average roughness; root mean square roughness skewness and kurtosis were calculated. The stoichiometric chemical composition were confirmed by EDAX analysis and it revealed the presence of O (-2), Cu2+, Ni2+, and Fe3+ elements with desired atomic weight percentage of the films. The energy band gap (Eg) obtained from UV spectrum varies from 2.24 eV to 2.03 eV as a function of Cu2+. The M-H curves showed that, the saturation magnetization (M-s) linearly decreased and coercivity increases with increase in Cu2+ content which related can be to the large residual strain, which may induce an additional magnetic anisotropy. The specific electrical resistivity confirmed a good insulating character of the thin films. The dielectric constant decreased with increase in frequency. The present ferrite films can be well suitable for MLCIs operable in the radio frequency range and high frequency device application. (c) 2018 Elsevier B.V. All rights reserved.