Quasielastic neutron scattering study of hydrogen motion in A15-type Nb3 AlHx
Abstract
In order to study the mechanism and parameters of hydrogen diffusion in A15-type intermetallic Nb3Al , we have performed high-resolution quasielastic neutron scattering measurements in Nb3AlHx ( x=0.13 and 1.77) over the temperature range 10-407K . The experimental results are consistent with a coexistence of two hydrogen jump processes: the fast H motion along the chains formed by interstitial d (Nb4) sites and the slower H jumps from one chain to another. It is found that the modified Chudley-Elliott model taking into account the structure of the d -site sublattice gives a qualitative description of the experimental data for Nb3AlH0.13 . The faster jump process in Nb3AlH0.13 corresponding to the long-range H diffusion along the d -site chains is characterized by the activation energy of 194meV . In Nb3AlH1.77 the d -site chains are more than half filled, and the faster jump process is well described in terms of a model of local H jumps within pairs of nearest-neighbor d sites on the chains.
- Publication:
-
Physical Review B
- Pub Date:
- January 2006
- DOI:
- 10.1103/PhysRevB.73.014302
- Bibcode:
- 2006PhRvB..73a4302S
- Keywords:
-
- 66.30.Jt;
- 78.70.Nx;
- Diffusion of impurities;
- Neutron inelastic scattering