Formation and Transformation of TiO2 (Anatase) Solid Solution in the System TiO2—Al2O3

In the system TiO 2 —Al 2 O 3 , TiO 2 (anatase, tetragonal) solid solutions crystallize at low temperatures (with up to ∼ 22 mol% Al 2 O 3 ) from amorphous materials prepared by the simultaneous hydrolysis of titanium and aluminum alkoxides. The lattice parameter a is relatively constant regardless of composition, whereas parameter c decreases linearly with increasing Al 2 O 3 . At higher temperatures, anatase solid solutions transform into TiO 2 (rutile) with the formation of α‐Al 2 O 3 . Powder characterization is studied. Pure anatase crystallizes at 220° to 360°C, and the anatase‐to‐rutile phase transformation occurs at 770° to 850°C.