A combined experimental and modeling study of thermodynamics and kinetics of mechanochemical treatment for synthesis of Ni0.5Co0.5Fe2O4

Abstract

A combined experimental and modeling approach has been used to explain thermodynamic and kinetic aspects of mechanochemical treatment to synthesizeNi0.5Co0.5Fe2O4. After obtaining the desired phase from Fe2O3, Co3O4 and NiO as precursors via continuous and interrupted mechanochemical routs, the contributions of microstructure changes and temperature rise to total input energy were calculated. The fraction for the former was less than 1% and the remaining energy was lost mostly in the form of heat. Then, a theoretical model for calculation of temperature rise in particles at the point of collision was proposed. Based on the model results, the temperature rise during the continuous condition was higher than the interrupted one's which was verified by lower amount of microstrain, larger grain and particle size of the interrupted milled samples. To evaluate the amount of formed phase as a result of the simultaneous effects of temperature rise and microstructure changes, a phenomenological kinetic model was developed. The fairly good agreement between this model results and new experimental findings gives a strong support to the validity of the model. For instance, in the case of a sample which was milled continuously for 180ks, the model prediction and experimental results were 41.7 and 40.2, respectively.