Equilibrium between FeO-M2O (M = Na, Li) solid solution and oxygen in gas phase at 1273 K

The compositions of FeO-M2O (M = Na, Li) solid solution in equilibrium with Ar-H2-H2O mixture of fixed compositions at 1273 K were determined by analysis by means of a reduction method and a fire flame method. The concentration of cation vacancy calculated on the assumption of no interstitial cation-defect was smaller than that in hypothetical ideal binary solutions FeO-M2O. The vacancy concentration was tried to be calculated as a function of the content of M2O in the consideration of two external reactions, (13) and (14). The values of log K13 and log K14 were able to be expressed by linear functions of the concentration of M in the lattice, although the apparent equilibrium constants were dependent on the defect concentration and oxygen pressure. (author)