On the nature of the phase "ɳ-TiO2"
Conditions for a sulfate method for the synthesis of a metastable modification, which has been previously described as ‘‘Z-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 Z-phase is not a polymorph of TiO2 but is a pseudo-polymorph of titanium dioxide hydrate. It was demonstrated that nanoparticles of the lowtemperature Z-phase consist of the [TiO2xmH2O] core, the structure of which can be described as a superstructure in relation to anatase, and an amorphous shell containing TiO2x (trace amount), OH, HSO4 and water. The average crystallite size depends on the ratio of the constituents.