Kinetics of thermal decomposition of Co3O4 powder and single crystals

Abstract

The kinetics of the thermal decomposition of Co304 is described using a mixed-control model in which the reaction rate is controlled simultaneously by both a diffusional process and a chemical reaction. The observed dependence of the activation energy on the degree of decomposition, and the activation energies of the diffusion and of the chemical reaction are given.The thermal decomposition of Co304" Co304 ~ 3CoO + 1/202 leads to the formation of a layer of CoO. This layer is very compact and well attached to the surface of the unreacted grain, as shown in our previous work [1].In reference [1] we have shown that the kinetics of Co304 thermal decomposition under an oxygen partial pressure of 0.67 Pa can be described with very high accuracy by the following equation:where a is the degree of decomposition and k and n are constants. The above equation has been derived directly from a kinetic analysis of the experimental a vs.t curves. We have shown that Eq. (1) can be regarded