The redox interactions of iron, manganese, and copper ion pairs including absorption characteristics in a multicomponent soda-lime-silica glass, were investigated. Glasses containing 11-19 mol % Na 2 O were melted under an air atmosphere in an electric furnace at 1450 ° C for 8 h. The results of chemical analysis indicated that the redox pairs of Fe 2+ /Fe 3+ , Mn 2+ /Mn 3+ , and Cu + /Cu 2+ shift to more oxidized states as a function of increasing glass basicity. The redox interactions of individual pairs, e.g., Fe 2+ /Fe 3+ -Mn 2+ /Mn 3+ , Fe 2+ /Fe 3+ -Cu + /Cu 2+ , and Mn 2+ /Mn 3+ -Cu + /Cu 2+ , were not strong but changed with glass basicity. For the three redox pairs, Fe 2+ /Fe 3+ -Mn 2+ /Mn 3+ -Cu + /Cu 2+ , both Mn 3+ and Cu 2+ ions simultaneously and proportionally oxidized Fe 2+ to Fe 3+ and did not affect one another. The reaction constants log Q 2 of Fe 2+ /Fe 3+ -Mn 2+ /Mn 3+ and Mn 2+ /Mn 3+ -Cu + /Cu 2+ redox pairs decreased while the Fe 2+ /Fe 3+ -Cu + /Cu 2+ and three redox pairs systems changed markedly with increasing the glass basicity. The oxidizing and reducing powers of each ion changed only slightly in the present of one another, and the absorption spectra of all the single polyvalent elements confirmed to the Lambert-Beer law. The spectra depended directly on the concentrations of each absorbing ion. While the spectra of glass doped with more than one element confirmed the direction of the equilibrium shift, they were used only to predict the degree of interaction. These investigations gave consistent results.

The changes in glass structure and redox ratio, R (reduced ion to oxidized ion) of Mn 2+ -Mn 3+ , Cu + -Cu 2+ , Cr 3+ -Cr 6+ , Ni 2+ -Ni 3+ and Co 2+ -Co 3+ couples and optical absorption due to Mn 3+ , Cu 2+ , Cr 3+ , Ni 2+ and Co 2+ ions in industrial soda-lime-silica glass were investigated as a function of Na 2 O concentration in the range 11-19 mol%. With increasing Na 2 O concentration in the experimental glasses, the basicity, expressed as calculated basicity, Λ cal , increased. 29 Si NMR and X-ray diffraction were used to investigate the structural change in glasses. The NMR spectra showed high non-bridging oxygens (NBOs) when the basicity of glass was increased. The results were interpreted to be due to the tetrahedral networks; Q 4 species were depolymerized by replacing the bridging oxygens (BOs) with NBOs to Q 3 species. These results confirmed the shift of broadening peaks of XRD patterns. The redox reactions of the Mn 2+ -Mn 3+ , Cu + -Cu 2+ and Cr 3+ -Cr 6+ couples shifted more toward their oxidized ions due to the oxygen partial pressure, p(O 2 ), during melting and the oxide ion activity, a O2-, increased with increasing glass basicity. These changes caused the redox ratio of these ion couples to decrease. The Ni 2+ -Ni 3+ and Co 2+ -Co 3+ couples were assumed to be present only in the Ni 2+ and Co 2+ ions in these glasses, respectively. The optical absorption bands due to Mn 3+ , Cu 2+ , Cr 3+ , Ni 2+ and Co 2+ ions were also investigated. Their spectra occurred at constant wavelengths with different optical densities or intensities as a function of glass basicity. The increase in the intensities of the absorption bands of these absorbing ions, except for Cr 3+ ion, at the maximum wavelength, depends not only on the ion concentration but also on the increase of polarizability of oxide (-II) species, α oxide(-II) , surrounding the ions. This value affected directly the extinction coefficients of the ions, ε ion . The increase of ε ion caused the colour of glasses appearing in high intensity. In the case of Cr 3+ ion, the results were reversed such that the lower the concentration, the higher the intensities of colour.