Structure of lithium tellurite and vanadium lithium tellurite glasses by high-energy X-ray and neutron diffraction

xLi₂O–(100 − x)TeO₂ (x = 20 and 25 mol%) and xV₂O₅–(25 − x)Li₂O–75TeO₂ (x = 1, 2, 3, 4 and 5 mol%) glasses were prepared by melt-quenching and their thermal and structural properties were characterized by differential scanning calorimetry, Raman spectroscopy, high-energy X-ray diffraction and neutron diffraction and reverse Monte Carlo (RMC) simulations. The glass transition temperature increases steadily with an increase in V₂O₅ mol% in lithium tellurite glasses due to an increase in the average single bond energy of the glass network. The X-ray and neutron diffraction structure factors were modelled by RMC technique and the Te–O distributions show the first peak in the range 1.85–1.90 Å, with V–O = 1.75–1.95 Å, Li–O = 1.85–2.15 Å and O–O = 2.70–2.80 Å. The average Te–O coordination number decreases with an increase in Li₂O mol% in lithium tellurite glasses, and the V—O coordination decreases from 5.12 to 3.81 with an increase in V₂O₅ concentration in vanadium lithium tellurite glasses. The O–Te–O, O–V–O, O–Li–O and O–O–O linkages have maxima in the ranges 86°–89°, 82°–87°, 80°–85° and at 59^o, respectively. The structural analysis of tellurite glasses reveal significant short-range and medium-range disorder due to the existence of a wide range of Te–O and Te–Te distances in the first coordination shell.