Uranium disulfide
Uranium disulfide is an inorganic chemical compound of uranium in oxidation state +4 and sulfur in oxidation state −2. It is radioactive and appears in the form of black crystals.
Uranium disulfide has two allotropic forms: α-uranium disulfide, which is stable above the transition temperature and metastable below it, and β-uranium disulfide which is stable below this temperature. The tetragonal crystal structure of α-US2 is identical to α-USe2.
Uranium disulfide can be synthesized by reduction of gaseous hydrogen sulfide with uranium metal powder at elevated temperatures.