| Issue |
J. Phys. Colloques
Volume 48, Number C8, Décembre 1987
Fifth European Conference on Internal Friction and Ultrasonic Attenuation in Solids
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| Page(s) | C8-227 - C2-232 | |
| DOI | https://doi.org/10.1051/jphyscol:1987831 | |
J. Phys. Colloques 48 (1987) C8-227-C2-232
DOI: 10.1051/jphyscol:1987831
QUANTUM BEHAVIOUR OF TRAPPED H AND D IN Nb AND Ta
G. CANNELLI1, R. CANTELLI2 et F. CORDERO11 Istituto di Acustica "O.M. Corbino", CNR, Via Cassia 1216, I-00189 Roma, Italy
2 II Università di Roma, Dipartimento di Fisica, Via O. Raimondo, I-00173 Roma, Italy
Abstract
Internal friction measurements at liquid helium temperature
on Nb and Ta specimens containing oxygen (nitrogen) and doped with hydrogen
(deuterium) show peaks due to the tunnelling of H(D) trapped by O(N). The peak
at higher temperature in Nb-O(N)-H(D) and that observed in Ta-O-D are
interpreted as due to a two-level system (TLS), and fits to the relaxation
curves have been made. In Nb-O(N)-H(D) both 2-phonon and electron transistions
gave nearly equivalent fits, while in Ta-O-D the predominance of the
TLS-electrons interaction is revealed both by a sharp discontinuity of the
slope of the relaxation curve at the normal-superconductor transition
temperature and by the fit of the exprimental points. The parameters
characterizing the TLS and their coupling with phonons and electrons have been
estimated.