Oxidation of CoO studied with the perturbed angular correlation method

Article abstract of DOI:10.1002/bbpc.19900940102

The substages of the oxidation of CoO have been investigated with the PAC method during isochronal and isothermal annealings at low oxygen activity (10^-9 atm). The successive trapping of cation vacancies at the ¹¹¹In probe atoms up to the formation of spinel-like microclusters has been observed. The results of the PAC experiments are compared with those of X-ray diffraction and RBS analyses and confirmed by a PAC experiment for ¹¹¹In in Co₃O₄. A quantitative analysis of the oxidation kinetics in terms of first order rate equations yields an activation enthalpy of ΔH = 0.27(4) eV. It is found that the absorption of oxygen and the formation of vacancies at the surface are the rate controlling processes in this experiment.