Phase relations in the system Fe2O3-Cr2O3-TiO2 between 1000 and 1300 degrees C and the stability of (Cr,Fe)(2)Tin-2O2n-1 crystallographic shear structure compounds

Phase relations and the stability of crystallographic shear (CS) structure compounds (Cr,Fe)(2)Tin-2O2n-1 in the system Fe2O3-Cr2O-TiO2 were investiga ted between 1000 and 1300 degreesC. The ternary comprises five major solid solution series. These are as follows: an M2O3 series; an M3O5 series made up of two separate solid solution series-the first an orthorhombic pseudobr ookite M3O5 solid solution and the second a monoclinic M3O5 series based on the V3O5 structure type; an M4O7 series, and an M5O9 series. These latter three series represent lower homologues. (n = 3, 4, and 5) of the (Cr,Fe)(2 )Tin-2O2n-1 CS compound series. Between adjacent M3O5 and M4O7 and M4O7 and M5O9 solid solutions, ordered intergrowths may occur. The stability and co mpositional limits of the solid solution series and intergrowth phases are dependent upon the temperature and Fe:Cr ratio. At high-TiO2 contents, asse mblages may contain either members of the Andersson phase series Cr2Tin-2O2 n-1, a continuous CS structure series extending into the ternary, or a ruti le-based solid solution. A comparison of results from this study with previ ously published phase relations has led to a revised version of the Fe2O3-C r2O3-TiO2 phase diagram. (C) 2001 Academic Press.