Hydrogen Relaxation Process in HiPco Carbon Nanotubes Studied by Mechanical Spectroscopy
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Published:2006-08
Issue:
Volume:115
Page:163-168
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ISSN:1662-9779
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Container-title:Solid State Phenomena
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language:
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Short-container-title:SSP
Author:
Cantelli Rosario1, Paolone Achille2, Roth S.3, Dettlaff U.3
Affiliation:
1. Sapienza Università di Roma 2. Università di Roma La Sapienza 3. Max-Planck-Institut für Festkörperforschung
Abstract
The first mechanical spectroscopy experiments in HiPco carbon nanotubes from room temperature to 3 K revealed a thermally activated relaxation process at about 25 K for frequencies in the kHz range. The peak is due to the presence of a very mobile species performing about 103 jumps per second at the peak temperature. The activation energy obtained by the peak shift with frequency is Ea = 54.7 meV; the value of the pre-exponential factor of the Arrhenius law for the relaxation time, τ0 = 10-14 s, which is typical of point defect relaxation and suggests that the process is originated by the dynamics of hydrogen or by H complexes. The peak is much broader than a single Debye relaxation process, indicating the presence of intense elastic interactions in the highly disordered bundle structure. There are indications that the relaxation process is governed by a quantum mechanism.
Publisher
Trans Tech Publications, Ltd.
Subject
Condensed Matter Physics,General Materials Science,Atomic and Molecular Physics, and Optics
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