METAL-ALUMINA INTERFACE - INFLUENCE OF THE METAL ELECTRONEGATIVITY AND OF THE SUBSTRATES STOICHIOMETRY

The first stages of metal-alumina interfaces have been investigated de pending on metal deposit thickness. The modified Auger parameter (alph a') variation has been analyzed for a series of metals (Pd, Cu, Ni and Cr) of decreasing electronegativity. It appears that atoms with low e lectronegativity (Cr) promote the formation of an oxide phase at the i nterface, whereas atoms with a higher electronegativity (close to oxyg en (Pd)) induce an electronic transfer from the oxide substrate to the metal deposit. In the latter case, an interaction between the deposit ed metal atoms and the cations of the surface seems to determine the e lectronic transfer.