Cluster probabilities in ordered titanium monoxide TiO y as functions of the long-range order parameters

The thermodynamic method is being developed for calculating the titanium-oxygen phase diagram in the domain of existence of the nonstoichiometric titanium monoxide TiO _y with vacancies in the metallic and nonmetallic sublattices. To develop the adequate thermodynamic model, the ordering in TiO _y was studied in detail by the x-ray diffraction method. The study showed that the low-temperature state of titanium monoxide is characterized by a nearly ideal atomic ordering in both metallic and oxygen sublattices. The structural analysis of the ordered Ti₅O₅ phase (space group C2/m) in titanium monoxide showed that one should use the multicluster approximation in modeling the free energy of the nonstoichiometric monoxide.