On the nature of the phase "eta-TiO2"

Conditions for a sulfate method for the synthesis of a metastable modification, which has been previously described as "eta-TiO2" (Dadachov, 2006), were found and the stability region of this phase in the hydrolysis temperature hydrolysis duration coordinates was determined. Investigation by a number of methods (X-ray powder diffraction, a differential dissolution method, thermogravimetry, IR spectroscopy, Raman spectroscopy) showed that the eta-phase is not a polymorph of TiO2 but is a pseudo-polymorph of titanium dioxide hydrate. It was demonstrated that nanoparticles of the low-temperature eta-phase consist of the [TiO2-x center dot mH(2)O] core, the structure of which can be described as a superstructure in relation to anatase, and an amorphous shell containing TiO2-x (trace amount), OH, HSO4 and water. The average crystallite size depends on the ratio of the constituents.