TiH

TiH, or titanium hydride, refers to a family of compounds formed between titanium and hydrogen with approximate stoichiometries represented as TiHx, where x typically ranges around 1.0 to 2.0. The most widely studied member is titanium dihydride (TiH2). These materials are of interest for hydrogen storage, materials science, and as precursors in metallurgical processes. In practice, nonstoichiometric hydrides with hydrogen contents between TiH and TiH2 can occur, especially under non-equilibrium synthesis conditions.

Structure and properties

Titanium hydrides, particularly TiH2, adopt a fluorite-type crystal structure in which titanium atoms form an fcc lattice and hydrogen atoms occupy tetrahedral interstitial sites. The hydrogen content can influence lattice parameters and phase stability, with nonstoichiometric compositions showing defects and disorder. TiH2 is relatively brittle and can undergo hydrogen-induced changes in mechanical properties. When exposed to air, TiH2 tends to oxidize to titanium oxides, releasing hydrogen gas in the process at elevated temperatures.

Synthesis and reactions

TiH2 is typically prepared by direct hydrogenation of titanium metal under elevated temperatures and hydrogen pressures. Alternative routes include chemical processing of precursors or dehydrogenation of higher hydrides. Decomposition of TiH2 upon heating (often around several hundred degrees Celsius) releases hydrogen and yields metallic titanium: TiH2 → Ti + H2. TiH and TiHx species can form under specific non-equilibrium conditions or at particular temperatures and pressures.

Applications

The primary interest in TiH lies in hydrogen storage research, where TiH2 can donate hydrogen upon controlled heating. It also serves as a source of hydrogen in thin-film deposition, and as a reactive titanium precursor in powder metallurgy and synthesis of titanium-based materials.

Safety and handling

Hydrides, including TiH2, can be reactive, especially as fine powders that may oxidize or release hydrogen. Handling is typically performed under inert or controlled atmospheres, with precautions to manage flammable hydrogen evolution and potential dust hazards.