Effect of elemental iron on the carbothermic reduction of the anatase and rutile forms of titanium dioxide

Effect of iron on the carbothermic reduction of anatase and rutile forms of titanium dioxide was studied. Differential thermogravimetric analysis indicated a significantly different reduction route in the presence of iron with a number of clear minima in the rate of mass loss observed. X-ray diffraction of the products at these minima indicated that rutile initially formed FeTiO3 which reduced to γ-Ti3O5, whilst anatase reduced through the mixed Ti(III/IV) phases of general formula TinO2n−1 to d-Ti3O5. The final stage was the reduction of Ti3O5 to the sub-stoichiometric carbide, TiC0.5. Iron was found to stabilise the Ti3O5 phases which were absent from an iron-free system, this is presumed to be due to partial substitution of trivalent iron for trivalent titanium.