DC Electrical Resistivity, Dielectric, and Magnetic Studies of Rare‐Earth (Ho³⁺) Substituted Nano‐Sized CoFe₂O₄

Abstract

The effect of Fe substitution by rare‐earth (Holmium; Ho3+) ions in CoFe2O4 (CFO) prepared by glycine nitrate process is investigated from electrical, dielectric, magnetic, and Mössbauer perspectives. The anticipated spinel cubic phase structure is confirmed by X‐ray diffractometry and Fourier transform infrared (FTIR) analysis which support the presence of a secondary phase of HoFe2O3 at higher Ho content. Field emission scanning electron microscope (FESEM) and transmission electron microscopic (TEM) micrographs confirmed that the incorporation of Ho3+ significantly reduced the grain size of the samples from 50 nm to 20 nm. The complex impedance and modulus spectroscopy are investigated as a function of frequency in the regime of 102–106Hz in the temperature range of 30–300 °C. The conduction mechanism is attributed to the hopping of both electrons and holes. Activation energies (Ea) obtained from the Arrhenius plots of the grain and the grain boundary conductions are ascribed to the hopping of charge carriers. Electrical modulus results specify the existence of the non‐Debye type of dielectric relaxation. A massive reduction in loss factor is successfully achieved. Room temperature magnetization measurements indicate a reduction in saturation magnetization and coercivity (hysteresis losses) with increasing Ho3+ content, which entails these materials to be used for magnetic data storage and magneto recording devices.

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