Activation of erbium films for hydrogen storage

Hydriding of metals can be routinely performed at high temperature in a rich hydrogen atmosphere. Prior to the hydrogen loading process, a thermal activation procedure is required to promote facile hydrogen sorption into the metal. Despite the wide spread utilization of this activation procedure, li...

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Bibliographic Details
Published in:Journal of applied physics 2011-06, Vol.109 (11)
Main Authors: Brumbach, Michael T., Ohlhausen, James A., Zavadil, Kevin R., Snow, Clark S., Woicik, Joseph C.
Format: Article
Language:English
Subjects:
ANNEALING
DESORPTION
EDUCATION
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELEMENTS
EMISSION
ENERGY
ENERGY LEVELS
ERBIUM
FERMI LEVEL
GAMMA RADIATION
HEAT TREATMENTS
HYDROGEN STORAGE
IONIZING RADIATIONS
KINETIC ENERGY
MASS SPECTRA
MASS SPECTROSCOPY
MATERIALS SCIENCE
METALS
PASSIVATION
PHOTOELECTRON SPECTROSCOPY
PHOTOEMISSION
RADIATIONS
RARE EARTHS
RECRYSTALLIZATION
SCATTERING
SECONDARY EMISSION
SORPTION
SPECTRA
SPECTROSCOPY
STORAGE
SURFACES
THIN FILMS
TIME-OF-FLIGHT METHOD
TRAINING
UPTAKE
X-RAY PHOTOELECTRON SPECTROSCOPY
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Summary:Hydriding of metals can be routinely performed at high temperature in a rich hydrogen atmosphere. Prior to the hydrogen loading process, a thermal activation procedure is required to promote facile hydrogen sorption into the metal. Despite the wide spread utilization of this activation procedure, little is known about the chemical and electronic changes that occur during activation and how this thermal pretreatment leads to increased rates of hydrogen uptake. This study utilized variable kinetic energy X-ray photoelectron spectroscopy to interrogate the changes during in situ thermal annealing of erbium films, with results confirmed by time-of-flight secondary ion mass spectrometry and low energy ion scattering. Activation can be identified by a large increase in photoemission between the valence band edge and the Fermi level and appears to occur over a two stage process. The first stage involves desorption of contaminants and recrystallization of the oxide, initially impeding hydrogen loading. Further heating overcomes the first stage and leads to degradation of the passive surface oxide leading to a bulk film more accessible for hydrogen loading.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.3590335