A SAXS study of V2O5·nH2O sols and gels

Small-angle X-ray scattering (SAXS) measurements on V₂O₅·nH₂O sols and gels, prepared by dissolving V₂O₅ glass into water at room temperature, show that there are V₂O₅ polymeric fibers entangled like random coils in the sol of n 5000, while the deviation from the random coil behavior occurs in the dilute sol of n 6000.

A Bragg peak appears at the scattering vector h 0.02 Å^?1 to be superimposed on an asymptotic h^?2-course in the SAXS curve of the concentrated sol of n 680. This means that the spatial correlation between V₂O₅ polymeric fibers takes place even in the fluid state.

V₂O₅·nH₂O sols completely lose fluidity at n 250 to transfer to the gel state, where V₂O₅ polymeric fibers begin to pile up in the parallel with a substrate surface. Such a layer structure is preserved up to the gel of n 4. However, V₂O₅ polymeric fibers are randomly oriented within each layer.