title: Concentration dependence of hydrogen diffusion in clamped vanadium (0 0 1) films.
abstract: The chemical diffusion coefficient of hydrogen in a 50 nm thin film of vanadium (0 0 1) is measured as a function of concentration and temperature, well above the known phase boundaries. Arrhenius analysis of the tracer diffusion constants reveal large changes in the activation energy with concentration: from 0.10 at 0.05 in H V-1to 0.5 eV at 0.2 in H V-1. The results are consistent with a change from tetrahedral to octahedral site occupancy, in that concentration range. The change in site occupancy is argued to be caused by the uniaxial expansion of the film originating from the combined hydrogen induced expansion and the clamping of the film to the substrate.
authors.affiliation: Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.forename: Lennard P A
authors.initials: LP
authors.lastname: Mooij
authors.forename: Sotirios A
authors.initials: SA
authors.lastname: Droulias
authors.forename: Heikki
authors.initials: H
authors.lastname: Palonen
authors.forename: Ola
authors.initials: O
authors.lastname: Hartmann
authors.forename: Gunnar K
authors.initials: GK
authors.lastname: Pálsson
authors.forename: Max
authors.initials: M
authors.lastname: Wolff
authors.forename: Björgvin
authors.initials: B
authors.lastname: Hjörvarsson