Influence of valence state of vanadium ions on structural and spectroscopic features of multi-component PbO–Al2O3–TeO2–GeO2 –SiO2 glass ceramics

Multi component PbO–Al2O3–TeO2–GeO2–SiO2 glasses doped with different concentrations of V2O5 ranging between 0 and 1.0 mol % were prepared by melt quenching technique. XRD and SEM techniques have been employed for the confirmation of glass ceramic nature of the samples. Optical absorption spectra of these samples exhibited two broad bands at about 626 and 831 nm corresponding to 2B2g→2B1g and 2B2g→2Eg transitions, respectively. The optical band gap has shown the maximal value, 3.16 eV for 0.4 mol % of nucleating agent V2O5 beyond this concentration it is observed to decrease. The EPR spectra of the doped glass ceramics have exhibited a well resolved hyperfine pattern consists of eight parallel and eight perpendicular lines which are the characteristics of VO2+ ions. The increase in the intensity of the resonance signal beyond 0.4 mol % of V2O5 has been attributed to the increase in the concentration of paramagnetic vanadyl ions. The analysis of these spectroscopic investigations reveals that the glass ceramics doped with 1.0 mol % of V2O5 are suitable for semiconducting devices.