The behaviour of uranium metal in hydrogen atmospheres

Abstract

The reaction between commercial H₂ and uranium metal leads to the formation of UO₂ due to traces of water vapour or oxygen. When extremely pure H₂ is used uranium hydride may be formed but, even with 99.9999% H₂ uranium dioxide forms preferentially. The present work identifies the presence of UH₃ in the X-ray photoelectron spectrum of a uranium sample which has been exposed to ca. 10¹⁰ L^†; H₂ at ca. 200 °C. This spectrum indicates that the hydride possesses a high degree of covalency, since the oxidation state of uranium in UH₃ appears to be ca. 1.4.