Thermodynamics of Redox Reactions between Oxides
of Glass Melt and Oxygen: II. Equilibrium of Iron
and Manganese Oxides with Oxygen

P. Buhler

Institut für Werkstoffwissenschaften III (Glas und Keramik), Friedrich-Alexander-Universität Erlangen–Nürnberg,
Martensstrae 5, 91058 Erlangen, Germany

Abstract—The thermodynamic approach developed in the preceding paper with respect to chemical transfor-
mations is applied to the equation of reaction between iron or manganese oxides and oxygen in a glass melt.
This equation of reaction is treated in terms of the mass action law. The transition of liquid iron (FeO and Fe₂O₃)
and manganese (MnO and Mn₂O₃) oxides into a glass melt is accounted for by the oxide activity coefficients.
The equations that relate the ratios q_M = / and (RC)_M = /x_MO [where and x_MO are the
mole fractions of the Fe₂O₃ (Mn₂O₃) and FeO (MnO) oxides in a melt, respectively] to the temperature, partial
pressure of oxygen, and total oxide content in a melt x_M = + x_MO are derived. These equations are used
in analyzing the experimental data available in the literature on the equilibrium concentrations of iron and man-
ganese oxides ( and x_MO) in melts of oxide glasses. In particular, it is demonstrated that the obtained equa-
tion describing the dependence of (RC)_Fe on x_Fe = + x_FeO predicts an increase in (RC)_Fe with a rise in
x_Fe, which is in agreement with the experimental data for model and commercial glasses.

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