Rietveld refined structural, morphological, Raman and magnetic investigations of superparamagnetic Zn-Co nanospinel ferrites prepared by cost-effective co-precipitation route

Zn2+-substituted cobalt ferrites (Co-ferrite) having the chemical formula Co1-xZnxFe2O4 (x = 0.0, 0.5 and 1.0) were fabricated by a co-precipitated wet chemical route. The analysis of weight loss percentage with spinel phase development and evaluation of sintering temperature of prepared samples were studied by applying the TG-DTA technique. Structurally refined XRD patterns of the prepared samples revealed the phase purity and cubic spinel structure with the Fd-3m space group. The fractional atomic positions and Rietveld refinement factors were estimated from Rietveld refined XRD pattern, and also, other variations of structural parameters with zinc substitution have been calculated from XRD data. Both the Rietveld refinement and W-H method were employed to calculate the crystallite size, and both of them presented the same calculated result. The variation in the shape of particles and average particle size with Zn2+ substitution in Co-ferrite was evaluated from the FE-SEM technique. The formation of cubic spinel structure and change in the modes of vibrations with respect to Zn concentration in Co-ferrite of all samples were observed from the best peak-fitted Raman spectra. All the magnetic properties decreased with increasing concentration of zinc investigated from M-H loops which were obtained with the application of the VSM technique. ZFC-FC curve reveals that the blocking temperature of Co-ferrite samples decreases with increasing Zn concentration. It is possible to modulate or adjust the magnetic properties of Co-ferrite nanoparticles by Zn2+ doping as a favorable material for biomedical applications such as drug delivery, magnetic hyperthermia and magnetic resonance imaging (MRI).