Plutonium dihydride is a non-stoichiometric chemical compound with the formula PuH. It is one of two characterized hydrides of plutonium; the other is PuH. PuH has a composition range of PuH â PuH. Metastable stoichiometries with an excess of hydrogen (PuH â PuH) can also be formed. PuH has a cubic structure. It is readily formed from the elements at 1 atmosphere at 100âÂÂ200ðC: When the stoichiometry is close to PuH it has a silver appearance, but gets blacker as the hydrogen content increases, additionally the color change is associated with a reduction in conductivity.
Studies of the reaction of plutonium metal with moist air at 200âÂÂ350 ðC showed the presence of cubic plutonium hydride on the surface along with PuO, PuO and a higher oxide identified by X-ray diffraction and X-ray photoelectron spectroscopy as the mixed-valence phase PuPuO. Investigation of the reaction performed without heating suggests that the reaction of Pu metal and moist air the production of PuO and a higher oxide along with adsorbed hydrogen, which catalytically combines with O to form water.
Like the free metal, plutonium dihydride is pyrophoric. On the surface of hydrided plutonium, it acts as a catalyst for the oxidation of the metal with consumption of both O and N from air.