Polyol-made stoichiometric Co0.2Ni0.3Zn0.5Fe2O4 nanoparticles: synthetic optimisation, structural, and microstructural studies

Crystalline and stoichiometric Co0.2Ni0.3Zn0.5Fe2O4 ferrite nanoparticles were successfully synthesised in polyol medium starting from the low-cost iron (III) chloride and acetates as precursors by the optimisation a number of synthetic parameters. The crystalline structure, the chemical composition, the microstructure, and the thermal stability of the as-produced powders were investigated by X-ray diffraction, infrared spectroscopy, energy dispersive X-ray, X-ray fluorescence spectroscopy, and transmission electron microscopy. We demonstrated that in contrast to the stoichiometric ferrite, which showed excellent thermal stability, the non-stoichiometric ferrites thermally decompose resulting in a stoichiometric ferrite as a major phase and hematite. The degree of deviation from the stoichiometry was calculated on the basis of a proposed decompositional thermal scheme and a quantitative analysis using Rietveld refinement.