MECHANISM OF SURFACE SPREADING IN VANADIA-TITANIA SYSTEM

Spreading of vanadia over TiO2 (anatase) supports of different specifi c surfaces has been investigated by XRD, XPS and ESR. It has been foun d that vanadia migration is favoured over well-developed anatase cryst al planes. At 723 K spontaneous spreading takes place, controlled by d iffusion of vanadium species through the vanadia monolayer. In reducin g atmosphere an induction period is observed, possibly initiated by fo rmation of a structurally modified titania surface layer. Amorphous va nadia is postulated as a transient form between crystalline V2O5 and t he vanadia monolayer.