Comparative study of the structure rearrangement in mixed and binary Zr-Tisol-xerogels

Structure rearrangement during gelation and thermal decomposition of the Zr /Ti sol-xerogels, chemically identical but prepared by different methods (m ixed and binary), was Studied by SAXS/WAXD with the use of SR. Observed, pr imary, particles in the systems under investigation in the sol state differ both in size and in shape. In the case of a mixed sol, a primary particle consists, probably, of a particle of hydrated titanium dioxide surrounded b y particles of hydrated zirconium dioxide. In this case, during gelation th e primary particle changes to a much smaller particle. In the case of a bin ary sol the primary particle is a complex Zr-Ti particle and changes insign ificantly during the gelation. During the thermal decomposition of both xer ogel systems, the formation of the final product (titanium zirconium oxide) goes through the mechanism of nucleation and growth of the new phase. (C) 2001 Elsevier Science B.V. All rights reserved.