Influence of heterogeneous inclusions on the process of formation, structural transformations, and growth of TiO2 nanocrystals

The processes of formation and growth of titanium dioxide nanocrystals with a certain structure, the phase transition of anatase to rutile in the presence of a heterogeneous inclusions during thermal and hydrothermal treatment are investigated in this work. Preformed TiO2 nanoparticles with anatase and rutile structure having different morphology were used as heterogeneous inclusions at the precipitation stage. It was shown that heterogeneous inclusions with this composition and structure could not be considered either as geometrical limitations preventing crystallization or as crystallization nuclei at the stage of titanium dioxide formation. A decrease in the temperature of the anatase-rutile structural transformation by 200 °C and a reduction in the average size of anatase crystallites in the presence of inclusions of the rutile modification in the initial material under hydrothermal conditions and during heat treatment were demonstrated. A conclusion was made about the effect of the size of anatase nanoparticles on their stability. The dependence of the morphological, dimensional, and surface characteristics of the resulting titanium dioxide nanoparticles on the parameters of hydrothermal synthesis and heat treatment, and the presence of inclusions in the reaction system is estimated.