Titanium(II) oxide
Titanium oxide is an inorganic chemical compound of titanium and oxygen. It can be prepared from titanium dioxide and titanium metal at 1500 °C. It is non-stoichiometric in a range TiO0.7 to TiO1.3 and this is caused by vacancies of either Ti or O in the defect rock salt structure. In pure TiO 15% of both Ti and O sites are vacant. Careful annealing can cause ordering of the vacancies producing a monoclinic form which has 5 TiO units in the primitive cell that exhibits lower resistivity. A high temperature form with titanium atoms with trigonal prismatic coordination is also known. Acid solutions of TiO are stable for a short time then decompose to give hydrogen:
Gas-phase TiO shows strong bands in the optical spectra of cool stars. In 2017, TiO was detected in an exoplanet atmosphere for the first time. Additionally, evidence has been obtained for the presence of the diatomic molecule TiO in the interstellar medium.
