Phase Equilibria in the Ferrite Region of the System FeO‐MgO‐Fe2O3

Abstract

Phase equilibria in the ferrite region of the system FeO–MgO–Fe2O3 have been investigated up to 1300°C. over an oxygen‐pressure range of 1.0 to 0.01 atmospheres. The five most important features of the equilibria in this system are as follows: (1) The spinel phase can exist with a deficiency of oxygen in the high‐magnesium compositions, (2) Mg++ replaces Fe++ in Fe3O4 beyond the “stoichiometric MgFe2O4,” corresponding to the formula (MgO)xMgFe2O4, where x = 0.092 ± 0.004 and is independent of temperature, (3) the spinel field does not include single‐phase composition corresponding to Mg‐Fe2O4, (4) the lattice constant of spinels in this system depends on cation distribution, and the extent of distribution changes as a function of temperature in turn depends on the magnesium concentration in the spinel, and (5) the spinel field near its terminus has little or no width. Copyright © 1960, Wiley Blackwell. All rights reserved