Titanium(II) oxide

Titanium(II) oxide (TiO) 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 TiO_0.7 to TiO_1.3 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 higher 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: