Activity of Iron Oxide in Magnesiowüstite in Equilibrium with Solid Metallic Iron

Abstract

By employing an electrochemical technique incorporating magnesia-stabilized zirconia electrolyte, the activities of iron oxide, Fe x O, were measured in magnesiowüstite, Fe x O-MgO solid solution, in equilibrium with solid metallic iron at temperatures between 1373 and 1573 K. The sub-regular solution model was applied to the Fe x O activities, and the calculated Fe x O activities were in good agreement with the experimental values in this study and the literatures at temperatures between 1073 and 1573 K with an accuracy of AE0:02.

Modelling of thermo-chemical properties over the sub-solidus MgO–FeO binary, as a function of iron spin configuration, composition and temperature

“…Taking then into account that ΔF(T,x Fe ) HTpz-mixing < 0, −T × S(x Fe ) ideal mixing < 0 and Fig. 4 a-b Activity-composition relation at a 1,373 and b 1,523 K, obtained in this study (empty circles) compared to experimental results from emf measurements: empty diamonds refer to Hasegawa et al (2006) and empty triangles to Sreçec et al (1987) Fig. 5 Temperature dependence of the averaged discrepancy between the activity obtained in the present study and those obtained by Sreçec et al (1987) ΔF(T,x Fe ) mixing is positive/negative as a function of temperature, it ensures that the pure static energy contribution tends to favour de-mixing but it is offset by vibrational and configuration components of ΔF(T,x Fe ) mixing .…”

“…Note that HS provides absolute energy smaller than LS, and therefore, HS leads to a definitely more stable magnesio-wüstite system, at room pressure. ΔF(T,x Fe ) excess has allowed one to determine the activity of the FeO, which has then been compared with values obtained from emf (electromotive force) and gas measurements by Sreҫec et al (1987) and Hasegawa et al (2006). Figure 4a, b display at 1,373 and 1,573 K our results from computational modelling and experimental data.…”