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Equilibria and thermodynamic properties of the plutonium-hydrogen system

1980; Elsevier BV; Volume: 73; Issue: 1 Linguagem: Inglês

10.1016/0022-5088(80)90341-0

1878-2728

J.M. Haschke, A.E. Hodges, Charlene M. Smith, F. L. Oetting,

Hydrogen Storage and Materials

Equilibrium, kinetic and X-ray diffraction data show the existence of two stability regimes in the PuH system. A metastable solid solution between CaF2-type PuH1.9 and AlFe3-type PuH3.0 forms at low temperatures and behaves as an ideal solid solution. Equilibrium and calorimetric results show that the enthalpy of formation varies linearly from −38 to −50 kcal mol−1 between the lower phase boundary and the trihydride. The stable regime established at high temperature is similar to those of the MF2-MF3 (M  lanthanide) systems. A series of CaF2-related phases apparently forms between PuH1.9 and PuH2.5; a non-stoichiometric hexagonal (LaF3-type) hydride exists in the range PuH2.9–PuH3.0. A procedure for preparing pure hexagonal PuH3.00 is described and the hysteresis behavior of the PuH system is discussed.