Temperature programmed desorption characterization of oxidized uranium surfaces: relation to some gas-uranium reactions

A. Danon, J. E. Koresh, M. H. Mintz

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

The chemisorption characteristics and surface composition of oxidation overlayers developing on metals when exposed to oxidizing atmospheres are important in determining the protective ability of these layers against certain gas-phase reactions (e.g., corrosion and hydriding). In the present study, a special setup of supersonic molecular beam - temperature-programmed desorption was utilized to determine the different chemisorbed species present on oxidized uranium surfaces. The main identified species included water (in different binding forms) and hydrogen. The latter hydrogen originates from the water - uranium oxidation reaction, which produces uranium dioxide and two types of hydrogen: a near surface hydride and a surface-chemisorbed form that desorbs at a lower temperature than that of the hydride. Assignments of the different water desorption peaks to different binding sites were proposed. In general, four water desorption features were identified (labeled W0, W1, W2, and W3, respectively, in order of increasing desorption temperatures). These features correspond to a reversibly chemisorbed molecular form (W0), a more tightly bound water (chemisorbed on different type of oxide sites) or hydroxyl clusters (W1), and strongly bounded (possibly isolated) hydroxyl groups (W2). The highest temperature peak (W3) is related to the formation of complex water - carbo-oxy compounds and is present only on oxidation overlayers, which contain proper chemisorbed carbo-oxy species. The relation of the water and hydrogen thermal release behavior to some problems addressed to certain effects observed in hydrogen - uranium and water - uranium reactions is discussed. For the latter, a microscopic mechanism is proposed.

Original languageEnglish
Pages (from-to)5913-5920
Number of pages8
JournalLangmuir
Volume15
Issue number18
DOIs
StatePublished - 1 Jan 1999

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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