In situ X-ray diffraction study of decomposition kinetics in LaSrCoO4 at a low partial pressure of oxygen

Abstract

The kinetics of the decomposition of LaSrCoO4 under vacuum conditions was studied by in situ high temperature powder X-ray diffraction. This methodology can be used to study reaction kinetics under vacuum condition, identify all the species involved in the solid-state reaction and establish their evolution. When LaSrCoO4 is heated under low partial pressure of O2, oxygen vacancy ordering occurs at T > 400 °C. Further heating results in decomposition to La2O3, SrO and Co which is observed at temperatures higher than 710 °C. We obtained the activation energies of these stages by non-isothermal treatments using two different models: Starink and Ozawa. Energies of 202 and 35 kJ/mol were calculated for the ordering stage and the decomposition stage (for α > 0.7), respectively. A reaction model for the decomposition of LaSrCoO4 was determined applying the Coats- Redfern equation to the experimental data.