Molecular dynamics study of hydrogen diffusion in tantalum hydride
The method of molecular dynamics has been used to study the diffusion process of hydrogen in tantalum hydride in its--diluted--$alpha$-phase. This study was stimulated by the unexplainable differences between quasi-elastic neutron scattering data and the results of jump diffusion model calculations. Most computations have been made with a fixed metal lattice in which a hydrogen atom moves, obeying Newton's law. The effect of a moving lattice on the diffusion process was also studied. The forces were calculated using pair potentials. The diffusion process is found to be dominated by hydrogen atom jumps between interstitial sites of tetrahedral symmetry in the body-centered cubic lattice. Mean residence and jump times are obtained together with the velocity autocorrelation function and the self-diffusion coefficient. A remarkable correlation is found between successive jumps, in the sense that the hydrogen atom has the tendency to keep moving between the four tetrahedral sites in one plane and around an octahedral site. It is suggested that this behavior might well explain the closer fit of the neutron data for small momentum transfers to a model with jumps between octahedral sites. (auth)
- Research Organization:
- Interuniversity Reactor Inst., Netherlands
- NSA Number:
- NSA-33-020652
- OSTI ID:
- 4089141
- Journal Information:
- Delft Prog. Rep., Ser. A, v. 1, no. 4, pp. 115-119, Other Information: Orig. Receipt Date: 30-JUN-76; Bib. Info. Source: NL (Netherlands (sent to DOE from))
- Country of Publication:
- Netherlands
- Language:
- English
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Related Subjects
Ceramics
& Other Materials-Ceramics & Cermets-Properties
Structure & Phase Studies
360202* -Materials-Ceramics
Cermets & Refractories- Structure & Phase Studies
*TANTALUM HYDRIDES- SELF-DIFFUSION
BCC LATTICES
HYDROGEN
INTERSTITIALS
LATTICE PARAMETERS
MOLECULES
NEUTRONS
REACTION KINETICS
SCATTERING