Hydrogen Interaction with Vacancies in Electron Irradiated Niobium

J. Čižek a, I. Procházka a, G. Brauer b, W. Anwand b, R. Gemma c, E. Nikitin c, R. Kirchheim c and A. Pundt c a Faculty of Mathematics and Physics, Charles University in Prague, V Holešoviv ckách 2, Praha 8, CZ-180 00, Czech Republic b Institut fűr Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, Postfach 510119, D-01314, Dresden, Germany c Institut fűr Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077, Göttingen, Germany

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Received: 3 09 2007;

Defect studies of Nb irradiated with 10 MeV electrons were performed in the present work by means of positron annihilation spectroscopy. The lattice defects were characterized by positron lifetime spectroscopy. Moreover, defect depth profiles were studied by slow positron implantation spectroscopy. The experimental investigations were accompanied by first principles theoretical calculations of positron parameters. It was found that irradiation-induced vacancies in Nb specimens are surrounded by H, which causes a shortening of the lifetime of trapped positrons. The influence of a Pd and Cr over-layer on the H concentration in the Nb specimens was examined.

DOI: 10.12693/APhysPolA.113.1293 PACS numbers: 78.70.Bj, 61.72.-y