Low temperature thermal expansion of pure and inert gas-doped Fullerite C60
| Autor: | V. G. Manzhelii, Bertil Sundqvist, Alexander V. Dolbin, V. G. Gavrilko, Alexander Bakai, B. G. Udovidchenko, A. N. Aleksandrovskii, V. B. Esel'son, G. E. Gadd, S. Moricca |
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| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Physics and Astronomy (miscellaneous) Liquid helium Relaxation (NMR) Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences General Physics and Astronomy Thermodynamics chemistry.chemical_element Disordered Systems and Neural Networks (cond-mat.dis-nn) Condensed Matter - Disordered Systems and Neural Networks Thermal expansion law.invention Condensed Matter::Materials Science Negative thermal expansion chemistry law Condensed Matter::Superconductivity Physics::Atomic and Molecular Clusters Dilatometer Inert gas Single crystal Helium |
| Popis: | The low temperature (2-24 K) thermal expansion of pure (single crystal and polycrystalline) C60 and polycrystalline C60 intercalated with He, Ne, Ar, and Kr has been investigated using high-resolution capacitance dilatometer. The investigation of the time dependence of the sample length variations on heating shows that the thermal expansion is determined by the sum of positive and negative contributions, which have different relaxation times. The negative thermal expansion usually prevails at helium temperatures. The positive expansion is connected with the phonon thermalization of the system. The negative expansion is caused by reorientation of the C60 molecules. It is assumed that the reorientation is of quantum character. The inert gas impurities affect very strongly the reorientation of the C60 molecules especially at liquid helium temperatures. A temperature hysteresis of the thermal expansion coefficient of Kr- and He- C60 solutions has been revealed. The hysteresis is attributed to orientational polyamorphous transformation in these systems. 18 pages, 12 figures |
| Databáze: | OpenAIRE |
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