Synthesis of Spinel MnCo2O4 by Thermal Decomposition of Carbonates and Kinetics of Thermal Decomposition of Precursor

Abstract

The cubic MnCo2O4 was prepared by calcining MnCO3-2CoCO3⋅1.5H2O above 600 ∘C in air. The precursor and its calcined products were characterized by thermogravimetry and differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometer. The result showed that high-crystallized MnCo2O4 with cubic structure [space group Fd-3m(227)] was obtained when the precursor was calcined above 600 ∘C in air for 6 h. Magnetic characterization indicated that cubic MnCo2O4 behaved weak magnetic behavior at room temperature. The thermal process of the precursor in air experienced three steps, which are: first, the dehydration of 1.5 water molecules, then the decomposition of MnCO3-2CoCO3 into cubic MnO2 and cubic Co3O4, and at last the reaction of MnO2 with Co3O4 into cubic MnCo2O4. Based on the KAS equation, the values of the activation energies associated with the thermal process of MnCO3-2CoCO3⋅1.5H2O were determined.