THE STRUCTURE OF VITREOUS V2O5-TEO2

A high resolution neutron diffraction study of a sample of vitreous V2 O5-TeO2. containing 5 mol% V2O5, has been performed using the LAD time -of-flight diffractometer at the ISIS spallation pulsed neutron source . Reciprocal space data were obtained to high scattering vectors, Q, a nd have been Fourier transformed to yield the real space correlation F unction, T(r). The first neighbour Te-O and O-O peaks in T(r) have bee n investigated using peak fitting techniques which suggest the presenc e of both TeO3 and TeO4 units. The shortest Te-O bond length is 1.91 A ngstrom, with two further contributions at 2.10 and 2.17 Angstrom, whi le the average O-O distance within the TeOn structural units is 2.76 A ngstrom. A comparison with the crystalline polymorphs of TeO2 indicate s that the structure of the glass is nearer to alpha-TeO2 than to beta -TeO2. The results from the present study are compared to earlier neut ron diffraction data for a V2O5-TeO2 glass containing 10.2 mol% V2O5. Fourier transform infrared spectra have been recorded for a series of three V2O5-TeO2 glasses over the range 400-1000 cm(-1) and analysed us ing deconvolution techniques. The results obtained are in good agreeme nt with the neutron data, particularly in respect of the existence of TeO3 and TeO4 structural units. (C) 1998 Elsevier Science B.V. All rig hts reserved.