Spectral investigations on VO2+ ion doped in CaO–SrO–Na2O–B2O3 glass systems

Glasses of the (20 − x)CaO–xSrO–(20 − y)Na2O–60B2O3 − y (CSNB) system with (5 ≤ x ≤ 15) mol% and y = 0.1 mol% of V2O5 were characterized by X-ray diffraction (XRD), EPR (Electron Paramagnetic Resonance), Optical absorption Spectra and FT-IR (Fourier transform Infrared Spectroscopy) studies. EPR spectra of all the glass samples exhibit resonance signals characterstic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in CSNB glasses were present in octahedral sites with tetragonal compression and belong to C4v symmetry. Spin-Hamiltonian parameters ‘g’ and ‘A’ were evaluated. The Optical band energy (Eopt) and Urbach energy (ΔE) were calculated from their ultra violet edges. By correlating EPR and Optical data the molecular orbital coefficients have been evaluated. IR spectra of these glasses were analyzed in order to identify the contribution of each component to the local structure that determines the physical properties of these glasses.