Phase Diagram of the System BaO‐Fe ₂ O ₃

Abstract

The phase diagram of the system BaO‐Fe 2 0 3 was determined by X‐ray diffraction, melting‐point measurement, and microscopic methods. Since the reduction of Fe 3+ to Fe 2+ was observed by chemical analysis in the samples heated at high temperature, especially in molten samples, the samples were heated at 1 atmosphere pressure of oxygen in the temperature region in which the liquid was in equilibrium; 1 atmosphere pressure of oxygen was su5cient to restrain the reduction of Fe 3+ . In the temperature region of solid‐solid equilibrium, the dissociation was not observed even when the samples were heated in air. BaO ‐ 6Fe 2 O 3 formed a solid solution with BaO.Fe 2 0 3 . The BaO:Fe 2 0 3 ratio of the solid solution was BaO.4.5Fe 2 0 3 at 1350°C. and BaO. 5.0Fe 2 0 a at 800°C. The precipitation micro‐structures of each primary solid solution were observed.