Gold oxide as precursor to gold/silica nanocomposites

Gold oxide films were prepared by reactive sputtering of pure gold in an oxygen plasma. These films were characterized by chemical and physical means to better understand the behavior of this metastable compound. Gold oxide, Au₂O₃, decomposes into the elements at 350°C. It does not react with dry carbon dioxide but does form a metastable bicarbonate in the presence of moisture and CO₂, releasing oxygen and eventually reverting to elemental gold. Gold oxide was generated by reactive sputtering along with silica in an oxygen plasma from Au-Si solidified alloys. Gold oxide decomposed upon pyrolysis to produce composites showing different characteristics depending on the gold content. Composites containing about 95 wt % gold produced reflective, conductive, and adherent films. Composites derived from an alloy containing 5 at. % gold produced a nanostructured material with gold clusters of about 5 nm in diameter dispersed in a silica matrix. This nanocomposite showed high resistivity, and capacitance with a dielectric constant of 400.