Titanium Monoxide or Hongquiite

Titanium monoxide or hongquiite [12137-20-1], chemical formula TiO, exhibits a very wide range of composition, extending approximately from 42 to 54 at. % oxygen (TiO to TiOj j ). It may be prepared by direct reduction by mixing stoichiometric amounts of titanium metal and titanium dioxide into a molybdenum crucible at 1600°C or reduction of the titanium dioxide with hydrogen under pressure at 130 atm and 2000°C. 

On heating the monoxide in air, the compound reverts to other titanium oxides as a function of temperature increase  

Reznichenko, V.A. Khalimov, F.B. (1959) Reduction of titanium dioxide with hydrogen. Titan i Ego Splavy, 2, 11-15. 

Its crystal structure has varying proportions of both titanium and oxygen vacancies. Density and y-ray lattice parameter measurements have shown that a third of the oxygen sites are vacant in TiO, a quarter of the titanium sites are vacant in TiOj j, and even in stoichiometric TiO about 15% of both sites are vacant. Above 990 C, the vacancies are arranged randomly, giving rise to diffraction patterns typical of the cubic NaCl-type structure. 

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