Electron spin resonance methods were used to study a CuO/CeO2 sample which had been subjected to various out-gassing, reduction and calcination treatments. The results indicated that the formation of O vacancies at the CeO2 surface aided the incorporation of Cu2+ ions into the support, some of which were located at specific positions in the oxide surface where Cu2+ dimers which consisted of pairs of similar ions could be stabilized. Upon increasing the calcination temperature, greater chemical interaction was produced; with the agglomeration of Cu to give species which exhibited ferromagnetic-like behavior. This was attributed to an enhancement of ionic mobility in the ceria lattice.
J.Soria, J.C.Conesa, A.MartÃnez-Arias, J.M.Coronado: Solid State Ionics, 1993, 63-65, 755-61