A comprehensive investigation of structural, thermal and electrical properties of T0.35Zn0.55Cu0.1Fe2O4 (T = Mn, Ni) nano ferrites

Highlights: • T0.35Zn0.55Cu0.1Fe2O4 (T = Mn, Ni) ferrite nanoparticles have been successfully synthesized by sol-gel method. • Structural analysis was carried out using X-ray diffraction and TEM to identify pure ferrite phases. • The variation of DC electrical resistivity of ferrite nanoparticles follows well known Arrhenius equation. • The frequency and temperature dependent dielectric properties were investigated. -- Abstract: In the present work, spinel ferrite T_0.35Zn_0.55Cu_0.1Fe₂O₄ (T = Mn, Ni) nanoparticles have been synthesized via the sol-gel method. We have used the X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) to investigate structural properties. Thermal stability of the samples was checked by Thermo-gravimetric and Differential thermal analysis (TG-DTA). The surface morphology and the shape of the particles were demonstrated by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The XRD patterns confirm the formation of the single-phase polycrystalline cubic spinel structure with Fd-3m space group. The average crystallite size evaluated from XRD data is found to be 13.7 nm and 15.6 nm which is consistent with the results of particle size estimated from TEM. The DC resistivity evaluated through the two-probe measurement, lowering of resistivity with a rise in temperature providing the traditional semiconducting behavior of spinel ferrites. The dielectric parameters such as dielectric constant (${\epsilon }^{\text{'}}$), ac conductivity (${\sigma }_{ac}$), and dielectric loss $\left(tan\delta \right)$ are investigated as a function of frequency and temperature. The results of dielectric measurement revealed a general dielectric dispersion due to the Maxwell-Wagner type of interfacial polarization and the hopping of charge carriers between Fe²⁺ and Fe³⁺ ions. The prepared samples exhibit low dielectric loss and high resistivity which make them suitable for high frequency microwave and power transform applications.