Reaction of Plutonium Dioxide with Water: Formation and Properties of PuO_(2+x)

摘要

Results show that PuO_(2+x), a high-composition (x ≤ 0.27) phase containing Pu(VI), is the stable binary oxide in air. This nonstoichiometric oxide forms by reaction of dioxide with water and by water-catalyzed reaction of dioxide with oxygen. The PuO_2 + H_2O reaction rate is 0.27 nanomoles per meter squared per hour at 25℃; the activation energy at 25° to 350℃ is 39 kilojoules per mole. Slow kinetics and a low lattice parameter-composition dependence for fluorite-related PuO_(2+x) are consistent with a failure to observe the phase in earlier studies. Perplexing aspects of plutonium oxide chemistry can now be explained.