Key Words:Titanium dioxide;Absorption - Calcination - Crystal growth - Heat treatment - Nanostructured materials - Oxidation - Phase transitions - Temperature;Composite nanocrystals - Composite oxides - Crystalline structure - Heterogeneous phase - Properties enduring high temperature calcining
Abstract:TiO<inf>2</inf> composite oxide nanocrystals were prepared by chemical co-precipitation method with Al<inf>2</inf>O<inf>3</inf> as heterogeneous composite phase, and the reaction mode, the dehydration approach of products and the composite amount of heterogeneity phase, which influence the properties of enduring high temperature calcining of TiO<inf>2</inf> composite oxide nanocrystals, were particularly studied. Nanocrystal particles of these composite oxides at various heat-treating temperatures were characterized in terms of optical absorbance in UV and visible region and structure. The results show that TiO<inf>2</inf> composite oxide nanocrystals were anatase entirely after calcined at 900°C, and well mixed crystalline structure among which the proportion (mass fraction) of anatase between rutile varies from 80:20 to 20:80 in the range of 950°C-1050°C. The composite nanocrystals after calcined at 950°C were spherical, average diameter 20-30 nm, dispersed equably, and had no reuniting phenomenon, and had the same optical absorbance in UV-vis region with TiO<inf>2</inf> nanocrystal calcined at 700°C. It was the surface absorption and bond inhibition mechanism of Al<inf>2</inf>O<inf>3</inf> existing as amorphism that notably delayed the phase transition process and particles growth of TiO<inf>2</inf> nanocrystals.
Volume:36
Issue:9
Translation or Not:no
