An investigation of the TiOx-SiO2/Mo(112) interface

The interaction of TiOx with SiO2/Mo(112) has been studied using high-resolution electron energy loss spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, and molecular adsorption. Ti at varying coverages was deposited onto a Sio(2)/Mo(112) surface followed by oxidation at 600K and annealing at various temperatures. TiOx disperses and covers the SiO2 surface after oxidation and annealing below 800K, whereas TiOx-SiO2 interfaces undergo significantly restructuring when annealed to temperatures above 1000K. Upon annealing a TiOx-covered SiO2(Monolayer)/Mo(112) surface, SiO2 diffuses to the surface and is bonded via Si-O-Ti linkages. SiO2 in this bonding configuration decomposes and desorbs more easily than from a Mo(112) surface where the binding is via Si-O-Mo linkages. On the other hand, for a TiOx-covered SiO2(multilayer)/Mo(112) surface, TiOx prefers to phase separate into three-dimensional clusters, minimizing the contact area with the SiO2 substrate. The annealing temperature: is a key parameter in defining the properties of TiOx-SiO2 mixed oxide surfaces. (C) 2004 Elsevier B.V. All rights reserved.