Abstract
The equilibrium of the system BaO-Fe2O3 has been studied by ordinary mineralographic methods. In some of the specimens of this system, the dissociation of Fe2O3 has been observed, and hence in such cases, the experiments were conducted under 1 atm. pressure of oxygen.
The results obtained in the present studies are summarized in Fig. 1. The existence of three compounds BaO⋅6Fe2O3, BaO⋅Fe2O3 and 2BaO-Fe2O3 was confirmed. The two binary eutectic reactions, Liquid ?? BaO.6Fe2O3+BaO⋅Fe2O3 at 1370°C and Liquid ?? BaO⋅Fe2O3+2BaO⋅Fe2O3 at 1330°C ware observed at the composition of 60.0 mole% and 41.2 mole% Fe2O3 respectively.
BaO.6Fe2O3 (85.7mole% Fe2O3) forms a solid solution by the dissolution of BaO⋅Fe2O3. The BaO: Fe2O3 ratio of the solid solution was 18.2: 81.8 mole at 1350°C and 16.7: 83.3 mole at 800°C, but the solubility of Fe2O3 in this phase was not observed. The solubility range of BaO.Fe2O3 phase is very narrow and the solubility of BaO⋅Fe2O3 in 2BaO⋅Fe2O3 was not observed. The compound BaO⋅6Fe2O3 is a hexagonal lattice, a =5.877, c=23.02Å, BaO⋅Fe2O3 a tetragonal lattice, a=6.02, c=9.45Å, and 2BaO⋅Fe2O3 a cubic lattice, a=8.07Å.
