Molybdenum ion as a structural probe in PbO-Sb₂O₃-B₂O₃ glass system by means of dielectric and spectroscopic investigations

¹ Dept. Physics, Acharya Nagarjuna University P.G. Centre, Nuzvid – 521 201 A.P., India
² Laboratory for Electro Optics Systems, ISRO, Bangalore-560 058, India

Corresponding author: nvr8@rediffmail.com

Received: 2 February 2006
Revised: 24 July 2006
Accepted: 7 November 2006
Published online: 24 January 2007

Abstract

PbO-Sb₂O₃-B₂O₃ glasses containing different concentrations of MoO₃ ranging from 0 to 5 mol % were prepared. A number of studies have been carried out on these glasses comprising differential thermal analysis, infrared and optical absorption, Raman and ESR spectra, magnetic susceptibility and measurements of dielectric properties (constant ε′, loss tan δ and a.c. conductivity over a range of frequency and temperature) of these glasses. The results have been analyzed in terms of different oxidation states of molybdenum ions. The analysis indicates that when the concentration of MoO₃ is ≤0.6 mol %, molybdenum ions exist mostly in the Mo⁶⁺ state, occupy network forming positions with MoO structural units and increase the rigidity of the glass network. When MoO₃ is present in higher concentrations, molybdenum ions seem to exist mostly in the Mo⁵⁺ state and occupy modifying positions.