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

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 W{sub 0}, W{sub 1}, W{sub 2}, and W{sub 3}, respectively, in the order of increasing desorption temperatures). These features correspond to a reversibly chemisorbed molecular form (W{sub 0}), a more tightly bound water (chemisorbed on different type of oxide sites) or hydroxyl clusters (W{sub 1}), and strongly bounded (possibly isolated) hydroxyl groups (W{sub 2}). The highest temperature peak (W{sub 3}) is related to the formation of complex water-carbo-oxy compoundsmore » 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.« less

Authors:
; ;
Publication Date:
Research Org.:
Nuclear Research Center-Negev, Beer-Sheva (IL)
OSTI Identifier:
20000527
Report Number(s):
CONF-9808111-
Journal ID: ISSN 0743-7463; LANGD5; TRN: US0000073
Resource Type:
Journal Article
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 15; Journal Issue: 18; Conference: Third international symposium on effects of surface heterogeneity in adsorption and catalysis on solids, Torun (PL), 08/09/1998--08/16/1998; Other Information: PBD: 31 Aug 1999; Journal ID: ISSN 0743-7463
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; URANIUM; OXIDATION; DESORPTION; CHEMISORPTION; PROTECTIVE COATINGS; WATER; HYDROGEN; URANIUM DIOXIDE

Citation Formats

Danon, A., Koresh, J.E., and Mintz, M.H. Temperature programmed desorption characterization of oxidized uranium surfaces: Relation to some gas-uranium reactions. United States: N. p., 1999. Web. doi:10.1021/la981210g.
Danon, A., Koresh, J.E., & Mintz, M.H. Temperature programmed desorption characterization of oxidized uranium surfaces: Relation to some gas-uranium reactions. United States. doi:10.1021/la981210g.
Danon, A., Koresh, J.E., and Mintz, M.H. Tue . "Temperature programmed desorption characterization of oxidized uranium surfaces: Relation to some gas-uranium reactions". United States. doi:10.1021/la981210g.
@article{osti_20000527,
title = {Temperature programmed desorption characterization of oxidized uranium surfaces: Relation to some gas-uranium reactions},
author = {Danon, A. and Koresh, J.E. and Mintz, M.H.},
abstractNote = {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 W{sub 0}, W{sub 1}, W{sub 2}, and W{sub 3}, respectively, in the order of increasing desorption temperatures). These features correspond to a reversibly chemisorbed molecular form (W{sub 0}), a more tightly bound water (chemisorbed on different type of oxide sites) or hydroxyl clusters (W{sub 1}), and strongly bounded (possibly isolated) hydroxyl groups (W{sub 2}). The highest temperature peak (W{sub 3}) 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.},
doi = {10.1021/la981210g},
journal = {Langmuir},
issn = {0743-7463},
number = 18,
volume = 15,
place = {United States},
year = {1999},
month = {8}
}