Tracer diffusion coefficient of tritium in vanadium and trapping effect due to zirconium impurity

The tracer diffusion coefficient of tritium in the alpha-phase of vanadium is measured in a temperature region from 323 to 523 K by making use of the glow discharge implantation method recently developed by the present authors. The obtained results are in good agreement with the data previously reported by Qi et al. (J. Phys. F: Metal Phys. 13 (1983) 2053). The trapping effect of zirconium on the diffusion of hydrogen isotopes is examined by using specimens containing a small amount of zirconium impurity. The existence of at least two kinds of trapping sources is deduced by analyzing the concentration dependence of tracer diffusion coefficient of tritium: one is due to zirconium and the other is due to a certain complex of zirconium with interstitial impurities such as oxygen and nitrogen. Trapping energies of 0.15 and 0.36 eV are assigned to the former and the latter, respectively. (C) 1998 Elsevier Science S.A.