The formation of the Co3O4 cobalt oxide within CoO substrate

The kinetics and mechanism of the Co3O4 formation in the interior of oxidized CoO substrate have been studied. It has been shown that the Co3O4 oxide is growing not only as a continuous layer on the surface of CoO, but it can also be detected within the CoO substrate in the form of isolated islands. The formation kinetics of Co3O4 islands are virtually independent of oxidation time. Two stage oxidation experiments using the O-18 isotope have demonstrated that the Co3O4 phase is formed within the CoO substrate not as a result of internal CoO oxidation but through substrate decomposition. (C) 2016 Elsevier Ltd. All rights reserved.