Optical, thermal, and structural properties of Nb₂O₅–TeO₂ and WO₃–TeO₂ glasses

Abstract

Glass samples from two systems, Nb₂O₅–TeO₂ and WO₃–TeO₂, were prepared at two melt quenching rates and characterized by density, DSC, UV-visible, and Raman spectroscopy. Addition of Nb₂O₅ decreased the density while increase in the WO₃ concentration increased the density. Glasses prepared at higher quenching rates had smaller densities than glasses of the same composition prepared at lower quenching rate although the short-range structure of both glasses were identical, as revealed by Raman spectroscopy. Optical studies found an intense absorption band just below the absorption edge in both the glass series. This band was attributed to electronic transitions of Nb⁵⁺ and W⁶⁺ ions and a lone pair of electrons on Te atoms. Glass transition temperature increased with increase in Nb₂O₅ and WO₃ mol% due to the increase in average bond strength in the glass network. Raman spectroscopy showed that the concentration of TeO₄ units decreased with the increase in Nb₂O₅ and WO₃ concentrations.

Keywords:

• tellurite glasses
• density
• X-ray diffraction
• UV-visible spectroscopy
• DSC
• Raman spectroscopy

Acknowledgements

Atul Khanna thanks UGC-DAE-Consortium for Scientific Research, Mumbai and Indore Centers, India for research grants.