Titania polymorphs by soft chemistry: Is there a common structural pattern?

The structural aspects of a soft chemical route¹ employed to obtain nitrogen-doped brookite, rutile, or anatase fine crystallite powders are revealed by total X-ray diffraction and atomic pair distribution function analysis. It is found that the route first passes through a heavily disordered phase consisting of nanosize layers of TiO₆ octahedra, similar to those occurring in the lepidocrocite-type structure. That phase is then transformed into a particular titania polymorph by rearranging the layers in a controlled way. The lepidocrocite-type structure thus again proves to be a very useful template in the soft chemistry of titania.