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Progress in pion-decay channelling: Refractory bcc metals at high and low temperatures |
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| Authors: | G Fabritius G Flik J Golczewski D Herlach G Jünemann M Krenke K Maier A P Pathak H Rempp A Seeger W Sigle E Widmann D W Cooke |
| Institution: | 1. Institut für Physik, Max-Planck-Institut für Metallforschung, Postfach 800665, D-7000, Stuttgart 80 2. Institut für Theoretische und Angewandte Physik, Universit?t Stuttgart, Pfaffenwaldring 57, D-7000, Stuttgart 80, Fed. Rep. of Germany 3. Los Alamos National Laboratory, 87545, Los Alamos, NM, USA |
| Abstract: | By means of π+/μ+ channelling, positive pions (π+) implanted intoTa, Mo, andW are investigated up to high temperatures. A striking observation is that the channelling effect disappears in a rather narrow temperature interval centred at 0.26 (Ta) to 0.51 (W) of the melting temperature. From studies of π+ trapping by oxygen atoms inTa estimates for the low-temperature π+ diffusivity inTa D π(23K)=1.4·10−10±0.3 m2s−1,D π(47K)=5.7·10−10±0.3 m2s−1] as well as for the binding enthalpy of π+ to 0 atoms (H B=7·10−2 eV) have been obtained. The diffusion data are in reasonable agreement with the theory of phonon-assisted tunnelling. |
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