Mechanothermal Solid-state Synthesis of Cobalt(II) Ferrite and Determination of its Heat Capacity by MTDSC

Cobalt ferrite (CoFe2O4) has been synthesized by a solid-state mechanothermal process, and its molar heat capacity has been determined. A stoichiometric mixture of CoC2O4 · 2H2O and FeC2O4 · 2H2O was subjected to a combination of mechanical activation (by high-energy milling) and thermal activation (by annealing at temperatures between 300 and 700 ◦C). The process was followed by thermogravimetric analysis and high-temperature X-ray powder diffraction. It has been shown that CoFe2O4 forms at all temperatures, though with different degrees of crystallization, while Co3O4 and Fe2O3 are the only products formed when starting from unmilled mixtures. The molar heat capacity of CoFe2O4 has been determined in the temperature range 60 – 400 °C by MTDSC. It has been shown that the molar CP values of CoFe2O4 samples produced at T ≥500 °C are close to each other while those of the samples produced at 300 and 400 °C are lower. Furthermore the CoFe2O4 samples prepared at T ≥500 °C show very similar microstructures.