High-temperature X-ray diffractometry is used to study Ti2O3 rhombohedral oxide formed by reduction of titanium dioxide, under
vacuum and in the presence of graphite or metallic titanium. The sesquioxide is characterised by a homogeneous field of very low oxygen
pressure, both boundary phases appearing independently from one another between 1073K and 1988K. The c/a = 2.660 value for Ti2-xO3
oxidized form of the equivalent hexagonal cell reaches c/a = 2.735 for Ti2O3 reduced form, which does not undergo quenching (c/a = 2.640 at 293K).