The TiO2 phase explored by the lattice constant and density method

Samples of TiO 2 of various colours (bluish black to yellowish white) were obtained by heating TiO2 at 1400 C. under oxygen of increasing pressure. At that temperature the dissociation pressure is about 2/3 arm. (in oxygen). The homogeneity region of the phase extends from about TiO~.gsa to TiO2.000 (39.845 to 40.05% b.w. of oxygen). The composition of the samples was determined from lattice parameter and density measurements. TiO2 of stoichiometric composition has a sound lattice with n' = 1.9999 +_ 0.0009 molecules per unit cell. The structure of the grayish and deeper coloured samples is imperfect, caused by missing oxygen ions (up to 0.034 ions per unit cell or 0"85% of all oxygen positions are vacant at the left phase border).