The Study on Thermal Analysis and Thermodynamic Characteristics of Spinel Compounds(ZnCo2O4, NiCo2O4)

The spinel compound was obtained by the thermal decomposition of Zn-Co and Zn-Ni gel prepared by sol-gel method using oxalic acid as a chelating agent. The formation of spinel compound has been comfirmed by thermogravimetric analysis (TGA), x-ray powder diffraction (XRD) and infrared spectroscopy (IR). The particle size of 13 nm similar to 16 nm was calculated by Scherrer` s equation. The sol-gel method provides a practicable and effective route for the synthesis of the spinel compound at low temperature (350 degrees C). The kinetic parameters such as activation energy (Ea) and pre-exponential factor (A) for each compound were found by means of the Kissinger method and Arrhenius equation. The decomposition of spinel compound has an activation energy about 155 kJ/mol. Finally, the thermodynamic parameters (Delta G(phi), Delta H-phi, Delta S-phi) for decomposition of spinel compound was determined.