Spectroscopic features of Tl₂O₃ mixed multi-component Li₂O-PbO-B₂O₃-SiO₂-Bi_{2< /sub>O3-V2O5 glass system}

The melt quenching procedure employs lithium lead borosilicate bismuth vanadate glasses containing varying amounts of Tl2O3 (from 0 to 5.0 mol%). Many spectroscopic investigations (Infrared, EPR and optical absorption) have also been explored. A vanadium ion exists both in the V4+ and V5+ states as shown by optical absorption and EPR experiments, and their ratio V4+/V5+ (redox ratio) is found to be lowest in glasses comprising 5.0 mol% of Tl2O3. The IR spectrum investigations demonstrated that when the concentration of Tl2O3 increases, the degree of disorder in the glass network reduces. Such shifts have now been ascribed to an increasing number of V5+ ions participating in network formation locations with VO5 crystal structures. This is due to thallium ion migration from octahedral coordination to tetrahedral coordination, as well as a thallium ion de-clustering effect on the glass structure.