DIFFUSION OF H AND D IN NB AND TA AT LOW-TEMPERATURES

The mobility of hydrogen and deuterium in niobium and tantalum has been studied by quenching to 4.2K and annealing between 10K and 100K. The concentration of quenched hydrogen has been computed from the resistivity increase after quenching. The decrease of the residual resistivity during annealing is interpreted by the trapping of hydrogen and by the formation of precipitations. By the variation of the hydrogen concentration and the impurity content, the annealing stage corresponding to the intrinsic diffusion of the hydrogen has been identified.