Trapping of hydrogen isotopes in molybdenum and niobium predamaged by ion implantation
The trapping of hydrogen isotopes at defects in Mo and Nb have been studied. Ion beams of 11- and 18-keV He/sup +/, 55-keV O/sup +/ and Ne/sup +/, and 500-keV Bi/sup +/ were used to create defects. Subsequently H or D was injected at room temperature by use of molecular beams of 16-keV H/sup +//sub 2/ and D/sup +//sub 2/. Appreciable enhancements were observed in the amount of H and D retained within the near-surface region of predamaged samples compared to samples with no prior damage. The total amount of D retained within the near-surface region was measured by means of the nuclear reaction D(/sup 3/He,p)/sup 4/He, and H depth profiles were measured via a resonance in the nuclear reaction /sup 1/H(/sup 19/F,..cap alpha gamma..)/sup 16/O. The H profiles correlate with the predicted predamaging ion profiles; however, appreciable tails to deeper depths for the hydrogen profiles are observed for the heavier predamaging ions. For a given predamage ion fluence, the amount of trapped deuterium increases linearly with incident deuterium fluence until a saturation in the enhancement is reached. The amount of deuterium trapped when saturation occurs increases with increasing predamage fluence. The experiments indicate that lighter ions, which create fewer primary displacements, are more effective per displacement in trapping hydrogen. An appreciable release of hydrogen is obtained upon annealing at 200 and 300 degreeC, and a preannealing experiment indicates this is due to detrapping rather than to any loss of traps. These temperatures suggest a much higher binding energy for the trapped hydrogen isotopes (approx.1.5 eV) than the available evidence gives for simple H-defect binding energies (approximately-less-than0.3 eV). The detailed trapping mechanism is not known. However, it is suggested on the basis of the high binding energies and the high concentrations of hydrogen which can be trapped that clusters of hydrogen may be formed.
- Research Organization:
- Institute of Physics, University of Aarhus, DK-8000 Aarhus C, Denmark
- OSTI ID:
- 7330794
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 48:3; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360106* -- Metals & Alloys-- Radiation Effects
ANNEALING
ATOMIC BEAMS
ATOMIC IONS
BEAM INJECTION
BEAMS
BISMUTH IONS
CATIONS
CHARGED PARTICLES
CHEMICAL ANALYSIS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEPTH DOSE DISTRIBUTIONS
DEUTERIUM IONS
DOPED MATERIALS
ELEMENTS
ENERGY RANGE
HEAT TREATMENTS
HELIUM IONS
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
ION BEAM INJECTION
ION BEAMS
ION IMPLANTATION
IONS
KEV RANGE
KEV RANGE 10-100
METALS
MOLECULAR ION BEAM INJECTION
MOLYBDENUM
NEON IONS
NIOBIUM
NUCLEAR REACTION ANALYSIS
OXYGEN IONS
PHYSICAL RADIATION EFFECTS
RADIATION DOSE DISTRIBUTIONS
RADIATION EFFECTS
REFRACTORY METALS
SPATIAL DOSE DISTRIBUTIONS
TRANSITION ELEMENTS
TRAPPING