Topotactic Transformation Reaction from Layered Titanate Nanosheets into Anatase Nanocrystals

Anatase nanocrystals with a special crystal plane on the surface were prepared by hydrothermal treatment of layered titanate nanosheets. The formation reaction of the anatase phase from the layered titanate nanosheets was investigated using TEM, SAED, XRD, and TG-DTA. The transformation from the layered phase into the anatase phase is a topotactic reaction. In the topotactic reaction, the TiO6 octahedra in titanate nanosheets slightly and equably shift from the positions of the layered lattice to the positions of the anatase lattice. Two kinds of definite relationships between the crystal-axis orientations of the layered structure and anatase structure were found, meaning that there are two routes in the in situ topotactic Structural transformation reaction. The anatase nanocrystals prepared by this method preferentially expose the (010) plane on their surfaces.