Densities of Melts in the FeO–Fe₂O₃–BaO System

Abstract

The densities of melts in the system FeO–FeO₂O₃–BaO and BaO–BaCO₃ have been measured under controlled atmospheres from the liquidus temperature to 1873 K by using the Archimedean method. The molar volumes of melts in the binary system BaO–BaCO₃ satisfy the additive rule. On the other hand, the molar volumes of melts in the ternary system FeO–Fe₂O₃–BaO show a possitive deviation from the additive rule and can be reproduced to within ±0.6% by the following equations:
V_M(cm³⁄mol)=15.54N_FeO+37.16N_Fe2O3+31.27N_Bao+3.05N_Fe2O3N_Bao⁄(N_Fe2O3+N_Bao) at 1673 K,
=15.66N_FeO+37.50N_Fe2O3+31.40N_BaO+2.98N_Fe2O3N_BaO⁄(N_Fe2O3+N_BaO) at 1773 K,
=15.80N_FeO+37.84N_Fe2O3+31.53N_BaO+2.91N_Fe2O3N_BaO⁄(N_Fe2O3+N_BaO) at 1873 K,
A similar positive deviation is not observed for the melts in the system FeO–Fe₂O₃–CaO. This suggests that the addition of Ba²⁺ cation results in the polymerization of ferrite anions as FeO₄⁵⁻.