Structural and magnetic properties of CoFe ₂ O ₄ ferrite nanoparticles doped by gadolinium

Abstract

Abstract This work’s main purpose is to investigate the effect of Gd 3+ substitution on the structural, cation distribution, morphological, and magnetic characteristics of cobalt ferrite nanostructures. The nanostructures were synthesized through the sol-gel auto combustion technique. X-ray diffraction (XRD) analysis with the Rietveld refinement through the Material Analysis Using Diffraction (MAUD) program confirmed a single-phase spinel structure for lower contents of Gd 3+ . However, for higher concentrations, a trace of second phase GdFeO 3 was evident. The crystallite size reduction from 17 to 11 nm with Gd 3+ doping confirmed the formation of nanocrystalline Co–Gd ferrite. Cation distribution was another parameter inferred from the experimental data of XRD analyzed by the MAUD program. Fourier-transform infrared spectra confirmed the formation of spinel structure through two prominent vibrational modes observed at the desired wavelength range. FESEM analysis confirmed the data obtained from the XRD about the structure and morphology of the nano samples. Saturation magnetization ( M S ) of the nano samples evaluated at 10 K showed a decreasing behavior from 94 to 86 emu g −1 by Gd 3+ doping, while a fluctuating trend of M S was observed at room temperature. Coercive field ( H C ) evaluated at 10 K reached a maximum value of about 1145 kA m −1 for the sample CoFe 1.96 Gd 0.04 O 4 , and then it decreased. At the same time, H C experienced no considerable change at 300 K. The possible concepts attributed to such a trend of H C were also investigated. Overall, the significant impact of Gd 3+ doping on the cobalt ferrite nanoparticles causes Gd–Co ferrite to have a desirable capacity of permanent magnet materials and storage of information with high density. As a result, this ferrite may be a proper candidate to be utilized, especially at lower temperatures.

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