The thermal decomposition of three magnetic acetates at their autogenic pressure yields different products. Why?

Article abstract of DOI:10.1002/ejic.200700146

We report on the one-stage, reproducible, solvent-free, competent and straightforward approach for the synthesis of fullerene-like Ni@C, Co@C, and Fe₃O₄@C core-shell nanostructures that can be scaled up. The single precursor reactions of low cost acetates of Fe, Co and Ni are separately conducted at a relatively low temperature (700°C) in a closed Swagelok reactor, as compared to other methods for the formation of graphitic layers. It is worth mentioning that although identical reaction parameters are employed, using the three acetate precursors, the graphitic carbon is coated on nanosized metallic Ni and Co cores, while Fe tends to form Fe₃O ₄, maintaining the same core-shell morphology. The systematic morphological, compositional, structural characterization and the room temperature magnetic susceptibility measurements of the as-made particles are carried out on a vibrating sample magnetometer. The plausible mechanism is based on the comparison between the dissociation products of three acetate precursors, their obtained experimental data, and calculations on the enthalpy and free energy changes. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.