Role of vanadium ions on structural, optical and electrochemical properties of the vanadate-lead glasses

Abstract New different series of xV 2 O 3 ∙(100 − x)[4PbO 2 ·Pb] glasses were prepared by melt-quenching method in a wide range of compositions defined by the parameter x = 0–30 mol% V 2 O 5 . InfraRed (IR) data reveal that by increasing the V 2 O 5 content, the glass network was transformed into a mixture of modified [VO 4 ] structural units, namely pyrovanadate and orthovanadate ones. The UltraViolet–Visible (UV–VIS) spectra show that addition of V 2 O 5 produces a gradual shift of the absorption edge towards the higher wavelength side (indicating the increase in concentration of vanadyl species) and a decrease of the gap energy. The shape of the Electron Spin Resonance (ESR) spectra changes with increasing the V 2 O 5 content suggesting that the interactions between vanadium centers strongly depend on x parameter which plays an important role. A hyperfine structure becomes visible in the glass with x = 20 mol% V 2 O 5 suggesting modifications of the glass structure caused by the network modifier. If the network is moderately disrupted the formation of Pb + 2 –V + 4 pairs was coupled through the oxygen atom or the interactions within V + 4 –O–V + 5 chains mask hyperfine structure. The shape of cyclic voltammograms, redox waves and good reversibility of the x = 20 mol% V 2 O 5 glassy electrode depends on the electrolyte acidity and electrochemically active species present in the glass network.