2274.     MICHEL, A., AND POUILLARD, E.  [New Family of Cubic Iron Sesquioxides.]  Compt. rend., vol. 228, 1949, pp. 680-681; Bull. soc. chim. France, 1949, p. 152; Chem. Abs., vol. 43, 1949, p. 8934.

        Mixed crystals of cubic (Fe1-xAlx)2O3 were obtained by oxidation of magnetite, x(Al2O3) (1-x)Fe2O3.FeO, in which Fe+++ ions are partly substituted by Al+++ ions.  The limit of solution is near to 10% Al2O3 at room temperature.  The parameter of the lattice decreases from 8.324 . for cubic Fe2O3 to the value 8.20 . continuously.  The solubility of Al2O3 increases at higher temperature.  The content of Al2O3 stabilizes the cubic form.  The temperature of quick transformation from the cubic form into the rhombohedral form is 200 for pure Fe2O3, 610 for the substitution x=0.03, and 650 for the substitution x=0.07.  A stabilized cubic mixture with 32% Al2O3 was obtained by quenching from 600; its Curie point was 410.  No modification in the stability of cubic Fe2O3 was obtained by Cr2O3, since it is insoluble in Fe2O3.