Nb-Ta, Nb-Mo and Nb-V oxides prepared from hybrid organic-inorganic precursors

New hybrid organic-inorganic materials based on group 5 elements and a well-defined polymeric matrix have been prepared and used as precursors for Nb-Ta and Nb-Mo mixed oxides. In this non-conventional but easily accessible route to multimetallic oxides, a copolymer of N,N-diallyl-N-hexylamine and maleic acid was synthesised and used as matrix to stabilise inorganic species generated in solution from (NH4)(6)Mo7O24-4H(2)O, NH4VO3, (gu)(3)[Nb(O-2)(4)] and (gu)(3)[Ta(O-2)(4)]. Solid-state studies indicate that the homogeneity of the blends can be kept up to about 0.5 mol Nb-v and Ta-v and 0.25 mol V-v per mol of repeat units of the copolymer. The calcination conditions of these homogeneous hybrid precursors were optimised to produce Nb-Mo, Nb-Ta and Nb-V oxides. While the thermal treatment of the Nb-V hybrid blends led only to a mixture of different phases, the characterisation of the final phases by X-ray diffraction (XRD) proved the formation of pure Nb2MO3O14 and showed that Nb-Ta oxides could be synthesised as single phases corresponding to a continuous series of solid solutions. (c) 2007 Elsevier Inc. All rights reserved.