IR and ESR investigations on V2O5–P2O5–BaO glass system with opto-electronic potential

The changes observed in the IR and ESR spectra of the xV2O5(1 − x)[0.8P2O5 ∙ 0.2BaO] glass system with 0 ≤ x ≤ 50 mol% show that vanadium oxide acts as a network modifier at low concentration (x ≤ 5 mol%) and as a network former for high content (x ≥ 10 mol%). Thus the IR bands belonging to the phosphate groups are strongly reduced except the specific bands of the short chain phosphate units due to the phosphate network depolymerization and the spectra are dominated by the vibrations characteristic for POP, POV and VOV linkages. At the same time the changes observed in the ESR spectra of these glasses are explained supposing the superposition of two signals, one with a well-resolved hyperfine structure typical for isolated V4+ ions and a broad line characteristic for clustered ions. The line width dependence versus V2O5 content shows that dipole–dipole interactions exist between vanadium ions until x = 5 mol% and the superexchange interactions prevail at high content (x > 10 mol%).

► The dual role, as modifier and network former of V2O5 was evidenced.
► Structural group evolution was evidenced from FTIR vibrational spectra.
► ESR spectra show the dipolar and superexchange interactions between vanadium ions.
► Fermi contact term indicates a poor contribution of 4s-V orbital to the VO bond.
► MO coefficients show an ionic character for both pi bonds.