Thin oxide film formation, metal tantalum

Thin films of a rare earth on another metal (or the other way round) were investigated by various authors. Flowever, real alloys were rarely formed and most of the time such studies were performed from a purely surface science point of view (electronic structure, spectroscopic properties. ..) and with no direct relevance to catalysis. One may quote, for example, the oxidation studies of tantalum and aluminum with thin cerium overlayers, carried out at low temperature, which showed that cerium enhances the oxide growth on both substrates (Braaten et al. 1989). However, the mechanism was not identical. No alloy was formed with tantalum and a catalytic oxidation took place. On aluminum, the formation of an intermetallic Ce—Al-O oxide layer was evidenced. 

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