Plutonium dihydride
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 – PuH. Metastable stoichiometries with an excess of hydrogen can also be formed. PuH has a cubic structure. It is readily formed from the elements at 1 atmosphere at 100–200°C: 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 200–350 °C 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.