TEM Investigation and FBB Model Explanation to the Phase Relationships between Titanates and Titanium Dioxides

Abstract

Sodium and hydrogen titanates fibers and three TiO2 polymorphs (TiO2 (B), anatase, and rutile) were prepared from inorganic titanium compounds by hydrothermal reaction and calcination. The nature and morphologies of the nanofibers with layered structure were investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was revealed that the phase transitions between titanates and titania (via proton titanate) could be interpreted systemically by the fundamental building blocks (FBB) model. The reaction also requires interconversion between some corner-linked and edge-linked pairs of TiO6 octahedrons. A generalized relationship of phase transitions between sodium/hydrogen titanates and titania by the wet-chemical process was proposed. A duplex pentagonal prism scheme was implied to summarize all of the phase relationships between titanates and titania.