Phase Relations in the System In2O3–TiO2–Fe2O3at 1100°C in Air

Phase relations in the system In2O3–TiO2–Fe2O3at 1100°C in air are determined by means of a classic quenching method. There exist In2TiO5, Fe2TiO5having a pseudo-Brookite-type phase and a new phase, In3Ti2FeO10having 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 In3Ti2FeO10are pyrochlore related witham=5.9171 (5) ?,bm=3.3696 (3) ?,cm=6.3885 (6) ?, and=108.02 (1)° in a monoclinic crystal system at 1100°C, anda0=5.9089 (5) ?,b0=3.3679 (3) ?, andc0=12.130 (1) ? in an orthorhombic system at 1200°C. The relationship between the lattice constants of these phases and those of the cubic pyrochlore type are approximately as follows:am=- ap+(- )bp+(- )cp,bm=- ap+(0)bp+( )cp,cm= ap+ (- )bp+( )cpand=109.47° in the monoclinic system, anda0=- ap+(- )bp+(- )cp,b0=- ap+(0)bp+( )cp, andc0= ap+(- )bp+ ( )cpin the orthorhombic system, whereap=bp=cp=9.90 (?) are the lattice constants of "In2Ti2O7" having the cubic pyrochlore type. All solid solutions of In3Ti2FeO10have incommensurate structures with a periodicity ofq×b*(q= 0.281–0.356) along theb*axis and the stoichiometric phase hasq= . InFeO3having a layered structure type is unstable between 750 and 1100°C.