Acoustic and thermal transport properties of hard carbon formed from C_60 fullerene

Scientific paper - Original scientific paper

• Author: J. C. Lasjaunias
• Author: M. Saint-Paul
• Author: A. Bilušić
• Author: Ana Smontara
• Author: S. Gradečak
• Author: Anđelka Tonejc
• Author: Antun Tonejc
• Author: N. Kitamura
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

We report on extended investigation of the thermal transport and acoustical properties on hard carbon samples obtained by pressurization of C60 fullerene. Structural investigations performed by different techniques on the same samples indicate a very inhomogeneous structure at different scales, based on fractal-like amorphous clusters on the micrometer to submillimeter scale, which act as strong acoustic scatterers, and scarce microcrystallites on the nanometer scale. Ultrasonic experiments show a rapid increase in the attenuation with frequency, corresponding to a decrease in the localization length for vibrations. The data give evidence for a crossover from extended phonon excitations to localized fracton excitations. The thermal conductivity is characterized by a monotonous increase versus temperature, power law T1.4, for T ranging from 0.1 to 10 K, without any well-defined plateau, and a strictly linear-in-T variation between 20 and 300 K. The latter has to be related to the linear-in-T decrease of the sound velocity between 4 and 100 K, both linear regimes being characteristic of disordered or generally aperiodic structures, which can be analyzed by the “phonon-fracton hopping” model developed for fractal and amorphous structures.

• Keywords (english): fullerene and related materials; X-ray difraction; high resolution transsmision electron microscope; transport properties; acoustic propeties
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical review B: Condensed matter and materials physics
• Numbering: vol. 66, no. 1, pp. 014302-11
• p-ISSN: 1098-0121
• e-ISSN: 1550-235X
• DOI: https://doi.org/10.1103/PhysRevB.66.014302
• URN:NBN: urn:nbn:hr:217:466395
• Publication: 2002
• Document URL: http://link.aps.org/doi/10.1103/PhysRevB.66.014302
• Type of resource: Text
• Access conditions: Open access
• Public note: Copyright (2002) by the American Physical Society.
• Created on: 2019-10-13 12:09:55