MIXED-OXIDE SURFACES - ULTRATHIN FILMS OF CAXMG(1-X)O

Nonstochiometric mixed oxides are often of interest for their novel ca talytic or material properties yet are often difficult to synthesize i n easily characterizable forms. We report on the use of low-temperatur e epitaxy of Ca and Mg under oxidizing conditions to yield mixed thin film oxides. Low-energy electron diffraction showed that the mixed oxi des grew as single crystals over a wide range of compositions. We comp are the water adsorption characteristics of the mixed oxide to that of CaO and MgO and find that the mixed oxide behavior is not a linear co mbination of the two pure oxide systems. The thermal stability of the mixed oxide film was checked by Anger electron ratios for an oxide-oxi de ''sandwich'' after various ''flash'' anneals. This and water adsorp tion results suggest intimate atomic-scale mixing exists until flashed above 1100 K.