Crystallography and crystallite morphology of rutile synthesized at low temperature

Rutile was prepared at low temperature with titanium trichloride in an acid- and oxygen-rich environment. Samples were characterized with X-ray powder diffraction, transmission electron microscopy, and thermogravimetry; rutileʹs crystalline structure was refined with the Rietveld method. Crystallites were needles with their largest dimension along c lattice parameter; they grew in bundles parallel to their length axis, and contained hydroxyls in their lattice and on their surface. When samples were annealed, dehydroxylation generated lattice defects that produced microstrains and created conditions for crystallite sintering at temperatures above 300°C. Titanium0-oxygen interaction in rutile depended on the annealing temperature, which gave rise to changes in the symmetry of the representative rutile titanium-oxygen octahedron. The atomic bond length between the oxygen atoms shared by adjacent octahedra decreased with the temperature, contracting the lattice. All this was caused by the variation of the number of hydroxyls in the lattice.