Phase relations in the system In2O3-TiO2-Fe2O3 at 1100°C in air

Phase relations in the system In2O3-TiO2-Fe2O3 at 1100 degrees C in air are determined by means of a classic quenching method, There exist In2TiO5:Fe2TiO5 having a pseudo-Brookite-type phase and a new phase, In3Ti2FeO10 having a solid solution range from In2O3:TiO2:Fe2O3 = 4:6:1 to In2O3:TiO2:Fe2O3 = 0.384:0.464:0.152 (mole ratio) on the line "InFeO3"-''In2Ti2O7.'' The crystal structures of In3Ti2FeO10 are pyrochlore related with a(m) = 5.9171 (5) Angstrom, b(m) = 3.3696 (3) Angstrom, c(m) = 6.3885 (6) Angstrom, and beta = 108.02 (1)degrees in a monoclinic crystal system at 1100 degrees C, and a(o) = 5.9089 (5) Angstrom, b(o) = 3.3679 (3) Angstrom, and c(o) = 12.130 (1) Angstrom in an orthorhombic system at 1200 degrees C, The relationship between the lattice constants of these phases and those of the cubic pyrochlore type are approximately as follows: a(m) = -1/4 a(p) +(- 1/2)b(p) + (-1/4) c(p), b(m) = -1/4 a(p) +(0) b(p) + (1/4) c(p), c(m) = 1/4 a(p) + (- 1/2)b(p) + (1/4)c(p) and beta = 109.47 degrees in the monoclinic system, and a(o) =- 1/4 a(p) + (- 1/2) b(p) + (- 1/4) c(p), b(o) = - 1/4 a(p) + (0) b(p) + (1/4) c(p), and c(o) = 2/3 a(p) + (- 2/3) b(p) + (2/3) c(p) in the orthorhombic system, where a(p) = b(p) = c(p) = 9.90 (Angstrom) are the lattice constants of "In2Ti2O7" having the cubic pyrochlore type. All solid solutions of In3Ti2FeO10 have incommensurate structures with a periodicity of q x b* (q = 0.281-0.356) along the b* axis and the stoichiometric phase has q = 1/3. InFeO3 having a layered structure type is unstable between 750 and 1100 degrees C. (C) 1999 Academic Press.