Oxidation thermodynamics of metal substrates during the deposition of buffer layer oxides

The oxidation state of a metal surface during the initial stages of deposition of an epitaxial oxide buffer layer is discussed from a thermodynamic viewpoint. The basic problem is one of minimizing oxidation of the surface of the metal while ensuring that the buffer layer oxide is able to form in the desired phase. Particular attention is paid to the deposition of CeO2, SrTiO3 and Y2O3-ZrO2 (YSZ) onto nickel. Such materials are candidates for use in the production of high-T-c coated conductors. Calculation of the Gibbs free energy changes for the oxidation reactions, under various regimes of vacuum and gas supply, suggest conditions which are reducing for the metal oxide but under which the buffet layer oxide remains stable. (C) 1998 Elsevier Science B.V.