Effects of composition on redox behaviors of antimony or arsenic ion in silicate melts by differential pulse voltammetry

Redox behaviors of antimony or arsenic ions in 16Na2O–10RO–74SiO2 (mol%, R = Mg, Ca, Sr, Ba) glass melts are investigated using differential pulse voltammetry. The redox ratio of each ion in every glass composition at a given temperature is estimated from the peak potential in each voltammogram. With increasing temperature, the redox equilibria shift to reduced states. The [Sb3+]/[Sb5+] and [Sb0]/[Sb3+] ratios show minimums at the composition of 16Na2O–10SrO–74SiO2 glass. It is not the case for arsenic ion in these glasses. The compositional variations of the redox ratios for arsenic ion, [As3+]/[As5+] and [As0]/[As3+], can be reasonably explained by the basicity of melt. It is suggested that the redox state of multivalent ion in silicate melt is affected not only by the basicity of melt but also by the stability of complex containing the multivalent ion.