Influence of gadolinium (Gd3+) ion substitution on structural, magnetic and electrical properties of cobalt ferrites

In present work, CoFe2-xGdxO4 nanoparticles with compositions x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1 were successfully synthesized by a sol-gel auto-combustion route sintered at 700 degrees C for 5 h. The effect of Gd3+ substitution on structural, morphological, magnetic and dielectric properties has been investigated. The X-ray diffraction with Rietveld refinement reveals that Gd-substituted Co-ferrites are prepared in a single-phase cubic spinel structure. Fourier transform infrared and Raman spectra confirm the single-phase formation of cubic spinel structure. It is observed that the lattice constants decrease from 8.3776 to 8.3711 angstrom with the substitution of Gd composition from x = 0.0 to 0.1. This is because of the distortion of the lattice structure with the introduction of Gd3+ ions. The crystallite size calculated from X-ray diffraction decreases from 29 to 19 nm with Gd3+ composition which confirms the formation of nanocrystalline samples. These values are good agreement with crystallite size calculated by the Williamson Hall method. The distribution of cations among the octahedral B and tetrahedral A-site was estimated by the computational method. Field emission scanning electron microscopy (FE-SEM) also confirmed the nanostructural nature in the range of 200-300 nm. Energy dispersive analysis (EDAX) proves chemical purity and stoichiometry. Fourier transform infrared spectra show the main vibration band of spinel structure. Gd-doped Co-ferrite shows the characteristics Raman active modes of spinel structure. Magnetic study reveals that saturation magnetization decreases from 77.37 to 51.38 emu/g with an increase of Gd composition in cobalt ferrites. It is observed that the coercivity of samples is increased from 976 to 1281 Oe with Gd substitution. Dielectric properties measured from LCR-Q meter exhibits the Maxwell-Wagner model. (c) 2020 Elsevier B.V. All rights reserved.