AVS 45th International Symposium
    Vacuum Technology Division Wednesday Sessions
       Session VT-WeA

Invited Paper VT-WeA7
Method for Measuring Deuterium in Erbium Deuteride Films

Wednesday, November 4, 1998, 4:00 pm, Room 329

Session: Vacuum Systems and Components
Presenter: J.R. Brangan, Sandia National Laboratories
Authors: J.R. Brangan, Sandia National Laboratories
S.M. Thornberg, Sandia National Laboratories
M.R. Keenan, Sandia National Laboratories
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Determining the quantity of deuterium in an erbium deuteride (ErD@sub 2@) film is essential for assessing the quality of the hydriding process but is a challenging measurement to make. First, the ideal gas law cannot be applied directly due to high temperature (950@super o@ C) and low temperature (25@super o@ C) regions in the same manifold. Additionally, the metal hydride does not release all of the deuterium rapidly upon heating and metal evaporation occurs during extended heating periods. Therefore, the method developed must provide a means to compensate for temperature inhomogeneities and the amount of deuterium retained in the metal film while heating for a minimal duration. This paper presents two thermal desorption methods used to evaluate the kinetics and equilibria of the deuterium desorption process at high temperatures (950@super o@ C). Of primary concern is the evaluation of the quantity of deuterium remaining in these films at the high temperature. A multiple volume expansion technique provided insight into the kinetics of the deuterium evolution and metal evaporation from the film. Finally a repeated pump-down approach yielded data that indicated approximately 10% of the deuterium is retained in the metal film at 950@super o@ C and approximately 1 Torr pressure. When the total moles of deuterium determined by this method were divided by the moles of erbium determined by ICP/AES, nearly stochiometric values of 2:1 were obtained for several erbium dideuteride films. Although this work presents data for erbium and deuterium, these methods are applicable to other metal hydrides as well. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DEAC04-94AL85000.