Spectroscopic and dielectric investigations on the role of molybdenum ions in lead niobium germanosilicate glasses

•Lead niobium germanosilicate glasses doped with MoO3 are prepared by melt quenching technique.•Optical and EPR studies revealed that molybdenum ions do exist in Mo5 + state in addition to Mo6 + state.•FTIR and Raman studies indicated an increase in the disorder and depolymerization of the glass network.•Dielectric studies confirmed the presence of Mo(V)O3 − complexes that act as a modifier in the glass network.

Glasses having composition 30PbO–2Nb2O5–10GeO2–(58-x)SiO2–xMoO3 (where x = 0 to 1 mol%) were prepared by melt quenching technique and characterized. Spectroscopic and dielectric studies are carried out in order to obtain information about the structural disorder of the prepared glasses. The results of the optical absorption, EPR, FTIR and Raman data are analyzed and discussed in view of the glass network structural changes determined by the evolution of molybdenum ions state. These spectroscopic studies have indicated that with increasing the concentration of MoO3 content a fraction of Mo6 + ions convert into Mo5 + ions. Accordingly, the formation of square pyramidal structural units having C4v symmetry with MoO bond is found to increase. Such modifications cause the structural disorder and depolymerization in the host glass network. Further, the variation of dielectric parameters with temperature has also indicated that the molybdenum ions do exist in Mo5 + state with Mo(V)O3 − complexes that act as modifiers in these glasses. The analysis of spectroscopic and dielectric studies revealed that the lead niobium germanosilicate glasses doped with MoO3 exhibiting semiconducting nature and are useful in the electronic devices.