Atomic-Scale Investigation on the Evolution of Tio₂-Anatase Prepared by a Sonochemical Route and Treated with NaOH

To date, the formation mechanisms of TiO₂, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO₂(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO₂-anatase with a crystallite size of 5.2 ± 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO₂-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO₂ mesostructures.