The influence of surface oxygen on uptake and release of deuterium by tantalum

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)

DOI:https://doi.org/10.1116/1.577622· OSTI ID:5594277

Wampler, W R ^[1]

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1. Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (US)

Here we examine the influence of surface oxygen on both the absorption of deuterium (D) from gas into solution in tantalum (Ta) and the release from solution back to the gas. The D uptake rate was proportional to gas pressure with a sticking coefficient of 0.0085{plus minus}0.0025 for clean Ta surfaces. Exposure to 10 Langmuirs (L) of O{sub 2}, giving about one monolayer of chemisorbed oxygen, decreased the D uptake rate by about two orders of magnitude. D release was studied using the D({sup 3}He,{ital p}){alpha} nuclear reaction to measure the concentration of D in the Ta versus time during release at constant temperature. D release was surface-limited and obeyed second-order kinetics for both clean and oxygen-covered Ta surfaces. The second-order kinetics show that D recombines from sites which are not saturated and therefore must have a smaller binding energy than the low-coverage chemisorption sites. Exposure to 10{sup 6} L of O{sub 2} resulted in an additional energy barrier to D recombination of 0.25{plus minus}0.04 eV/D which greatly reduces the D release rate. This activation barrier should also reduce D dissociation and uptake rates, and this is observed. The measured uptake and release rates are consistent with detailed balance.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5594277
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA) Vol. 9:3; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ATOM TRANSPORT
BINDING ENERGY
CHEMICAL REACTIONS
CHEMISORPTION
DEUTERIUM
ELEMENTS
ENERGY
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
METALS
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OXYGEN
RADIATION TRANSPORT
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
STABLE ISOTOPES
SURFACE PROPERTIES
TANTALUM
TRANSITION ELEMENTS
UPTAKE