Comparative study of the short-range structure of α-V2O5, α-TeO2 and xV2O5-(100 - x)TeO2 glasses using X-ray diffraction, Rietveld analysis and reverse Monte Carlo simulations.

Abstract

Vanadium-tellurite glasses, tetragonal TeO₂ and orthorhombic V₂O₅ crystalline samples were characterized for their atomic structure properties by synchrotron X-ray diffraction, pair distribution function analysis, reverse Monte Carlo simulations (RMC) and Rietveld analysis. The pair correlation function, G(r), of V₂O₅ shows the first peak at 1.61 Å. G(r) of TeO₂ shows three peaks at 1.57, 2.13 and 2.88 Å due to Te-O linkages of three different lengths, whereas the Te-Te atomic pair correlation shows a peak at 3.85 Å. The average coordination number of V with O in crystalline V₂O₅ is 4.39 while that of Te with O in crystalline TeO₂ is 3.71. G(r) of the vanadium tellurite glass shows the first peak at 1.90 Å due to overlapping Te-O and V-O atomic pair correlations. The RMC analysis on diffraction data of glasses found that the V-O coordination number is in the range 5.27-5.59 and the Te-O coordination number is 5.39-5.67. However, it is found that these coordination numbers cannot be clearly defined due to short-range disorder.