Characterization and sintering behaviour of submicrometre titanium dioxide spherical particles obtained by gas-phase hydrolysis of titanium tetrabutoxide

Spherical fine (similar to 0.7 mu m) titania powders were prepared by vapour-phase hydrolysis of a titanium tetrabutoxide/butanol solution. Powder X-ray diffraction showed that as-prepared powders were amorphous and crystallized to anatase when calcined at 450 degrees C. Although the spherical titania particles shrank on calcination and retained the spherical shape, the primary particles grew to a notable extent after calcining. The individual calcined titania spheres were constituted by microporous agglomerates of about 13 nm primary anatase particles. When isopressed at 200 MPa, the titania spheres were crushed to form dense green bodies (similar to 55% theoretical density). These green compacts gave dense bodies (> 99%) of rutile when sintered at 1030 degrees C for 2 h with a submicrometre and quite uniform microstructure.