Phase Relations in the System Fe_2O_3-Cr_2O_3-TiO_2 between 1000 and 1300 deg C and the Stability of (Cr, Fe)_2Ti_(n-2)O_(2n-1) Crystallographic Shear Structure Compounds

摘要

Phase relations and the stability of crystallographic shear (CS) structure compounds (Cr,Fe)_2Ti_(n-2)O_(2n-1) in the system Fe_2O_3-Cr_2O_3-TiO_2 were investigated between 1000 and 1300 deg C. The ternary comprises five major solid solution series.These are as follows: an M_2O_3 series; an M_3O_5 series made up of two separate solid solution series-the first anorthorhombic pseudobrookite M_3O_5 solid solution and the second a monoclinic M_3O_5 series based on the V_3O_5 structure type; an M_4O_7 series; and an M_5O_9 solid solutions, ordered intergrowths may occur. The stability and compositional limits of the solid solution series and intergrowth phases are dependent upon the temperature and Fe:Cr ratio. At high-TiO_2 contents, assemblages may contain either members of the Andersson phase series Cr_2Ti_(n-2)O_(2n-1), a continuous CS structure series extending into the ternary, or a rutile-based solid solution. A comparison of results from this study with previously published phase relations has led to a revised version of the Fe_2O_3-Cr_2O_3-TiO_2 phase diagram.