Europhys. Lett, 36 (5), pp. 385-390 (1996)
A mechanical-spectroscopy study of the anelastic relaxation of hydrogen pairs in hexagonal single crystals
B. Kappesser , H. Wipf , R. G. Barnes and B. J. Beaudry
Institut für Festkörperphysik, Technische Hochschule
Darmstadt, Hochschulstraße 6, D-64289 Darmstadt, Germany
Ames Laboratory, Iowa State University - Ames, Iowa 50011, USA
(received 24 July 1996; accepted in final form 27 September 1996)
PACS. 61.72Ji - Point defects (vacancies, interstitials, color centers, etc.) and
PACS. 62.40 - Anelasticity, internal friction, stress relaxation, and mechanical resonances.
PACS. 66.30Jt - Diffusion, migration, and displacement of impurities.
Abstract:We have performed a mechanical-spectroscopy study on hcp single crystals (, vibrating-reed technique, 280 to 1750 Hz). In agreement with previous data from polycrystalline , we find an anelastic relaxation peak at . Our single crystals show a large anisotropy in the relaxation strength which demonstrates that this peak results from a Zener relaxation of hydrogen (H) pairs. Two types of H jumps determine the relaxation kinetics. Comparison with previous QNS data identifies the jumps that cause the relaxation, showing further that their jump rates follow, over ten orders of magnitude, an Arrhenius law with an activation energy of .
Copyright EDP Sciences