The structure of vitreous V 2O 5–TeO 2

Abstract

A high resolution neutron diffraction study of a sample of vitreous V 2O 5–TeO 2, containing 5 mol% V 2O 5, 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, and have been Fourier transformed to yield the real space correlation function, T( r). The first neighbour Te–O and O–O peaks in T( r) have been investigated using peak fitting techniques which suggest the presence of both TeO 3 and TeO 4 units. The shortest Te–O bond length is 1.91 Å, with two further contributions at 2.10 and 2.17 Å, while the average O–O distance within the TeO n structural units is 2.76 Å. A comparison with the crystalline polymorphs of TeO 2 indicates that the structure of the glass is nearer to α-TeO 2 than to β-TeO 2. The results from the present study are compared to earlier neutron diffraction data for a V 2O 5–TeO 2 glass containing 10.2 mol% V 2O 5. Fourier transform infrared spectra have been recorded for a series of three V 2O 5–TeO 2 glasses over the range 400–1000 cm −1 and analysed using deconvolution techniques. The results obtained are in good agreement with the neutron data, particularly in respect of the existence of TeO 3 and TeO 4 structural units.