The Iron‐Oxygen Equilibrium in Glass: Effect of Platinum on the Fe ²⁺ /Fe ³⁺ Equilibrium

Abstract

A number of experiments were performed on iron‐containing sodium disilicate melts in air. It was found that it was not possible to obtain an equilibrium between Fe 2+ and Fe 3+ in platinum crucibles owing to the reaction between platinum and iron, whereas in alumina crucibles the equilibrium was rapidly established. Thermodynamic calculations of the reaction 2FeO (in Na 2 O‐2SiO 2 ) +½O 2 (g) = Fe 2 O 3 (in Na 2 O‐2SiO 2 ) showed that the equilibrium went more and more to the right with increasing temperature. The standard free energy, enthalpy, and entropy for the reaction were calculated.