Optical, physical and structural studies of vanadium doped P2O5–BaO–Li2O glasses

• These glasses exhibit low refractive index they possible application in optical glasses.
• The EPR spectra exhibit resonance signals which are the characteristics of VO2+ ions in tetragonally compressed octahedral sites.
• DSC and IR study show changes in phosphate network as a function V2O5 concentration.

Glasses in the compositions (Li2O)25–(BaO)25–(P2O5)50−x–(V2O5)x (with x=0.5,1.0,1.5,2.0,2.5, and 3.0 mol%) have been prepared by the conventional melt quenching technique. X-ray powder diffractrogram show broad peaks which conforms glassy nature of the sample. Differential scanning calorimetry (DSC) thermograms show characteristic glass transition temperature (Tg) and it increases with increasing substitution of V2O5 for P2O5. The measured physical parameters like density, refractive index, ionic concentration and electronic polarizability are found to vary linearly with increasing x. Infrared spectra exhibits few bands, which are attributed to (P=O)AS, (P=O)S, (V=O), (P–O–P)AS,P–O–V, (P–O–P)AS and O–P–O vibrations. The optical absorption spectra of VO2+ ions in these glasses show three bands and are assigned to the 2B2→ 2E,2B2→ 2B1 and 2B2→ 2A1 transitions. Electron paramagnetic resonance spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of Spin-Hamiltonian parameters indicate that the VO2+ ions are present in octahedral sites with tetragonal compression and belong to C4V symmetry.

The above figure present the EPR spectra of (Li2O)25–(BaO)25–(P2O5)47.5–(V2O5)2.5 and (Li2O)25–(BaO)25–(P2O5)47–(V2O5)3 glasses. The figure clearly indicates the hyperfine split spectrum due to 51V.Figure optionsDownload as PowerPoint slide