Temperature-Programmed Desorption of Pyridine on Silica Overlayers Deposited on ZrO2 and TiO2 by Chemical Vapor Deposition of Si(OC2H5)(4)

Silica overlayers deposited on ZrO and TiO by chemical vapor deposition of Si(OC2H6)(4) have been characterized by using temperature-programmed desorption of pyridine and Auger electron spectroscopy (AES). On ZrO2, the pyridine uptake decreased slowly with silica deposition until the silica fraction (Si/(Si + Zr)) reached 40%; then it decreased strongly with further deposition. On Tio(2,) with silica deposition pyridine adsorption also decreased slowly up to an AES silica fraction of 45%. With additional deposition of silica, the pyridine uptake then remained constant. These results agree with our previous conclusion that a thin SiOx film covering the entire substrate was formed on ZrO2 and that a mixed oxide layer was formed on TiO2.