Formation of Nanostructured Li4Ti5O12-Based Composites upon Hydrothermal Treatment of Their Components

Nanostructured Li4Ti5O12-based composites in the form of microspheres consisting of randomly packed prism-like particles have been prepared via hydrothermal treatment of TiO2 xerogel in aqueous LiOH solutions, followed by calcination of the reaction products at t >= 550 degrees C. The phase composition of the hydrothermally prepared spherical particles has been shown to correspond to alpha-Li2TiO3. According to elemental analysis data, the titanium and oxygen were nonuniformly distributed over the microspheres. Sequential calcination of the microspheres at t <= 750 degrees C led first to the alpha-Li2TiO3 -> beta-Li2TiO3 phase transformation and then to the formation of nanostructured Li4Ti5O12 spinel or spinel-based composites (Li4Ti5O12/TiO2 and Li4Ti5O12/beta-Li2TiO3). The Li4Ti5O12 microspheres calcined at 750 degrees C consisted of not only the major crystalline phase but also X-ray amorphous TiO2 (anatase) and beta-Li2TiO3 as impurity phases, which could not be detected by X-ray diffraction.