Influence of trivalent Cr ion substitution on the physicochemical, optical, electrical, and dielectric properties of sprayed NiFe₂O₄spinel-magnetic thin films

In this study, we mainly investigated the effects of trivalent Cr ion substitution on the properties of nickel ferrite (NCF) spinel-thin films. The as-prepared spinel thin films were characterized by thermogravimetry-differential thermal analysis (TGA-DTA) to comprehensively examine their phase transition. X-ray diffraction (XRD) analysis revealed that the prepared films have a single-phase face-centered cubic crystal structure. A Raman study confirmed the arrangement of the inverse-cubic spinel structure of these spinel-thin films. Field-emission scanning electron microscopy (FE-SEM) images verified the slight agglomeration of particles. Similarly, transmission electron microscopy (TEM) images together with selected area electron diffraction (SAED) patterns supported the XRD results. PL spectra showed enhanced near band emission (NBE) intensity due to the passivation of oxygen vacancies by Cr3+ substitution. The DC electrical resistivity (ρ) increases from 1.4 × 10-6 Ω cm to 4.42 × 10-6 Ω cm at room temperature. Dielectric parameters were studied as a function of frequency in the range of 1-10 MHz at 300 K, and these parameters decreased with the increasing Cr3+ ion concentration in the spinel-thin films. The obtained results indicate the applicability of the fabricated thin films in high-frequency electronic devices.