| 1. |
- Aleksandrovskii, A. N., et al.
(författare)
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Low-temperature thermal expansion of pure and inert gas-doped fullerite C60
- 2003
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Ingår i: Fizika Nizkikh Temperatur (Kharkov). - : AIP Publishing. - 0132-6414 .- 1816-0328. ; 29:4, s. 432-442
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Tidskriftsartikel (refereegranskat)abstract
- 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 the high-resolution capacitance dilatometer. The investigation of the time dependence of the sample length variations deltaL(t) on heating by deltaT 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 a quantum character. The inert gas impurities affect the reorientation of the C60 molecules very strongly, 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.
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| 2. |
- Aleksandrovskii, A. N., et al.
(författare)
-
Effect of argon on the thermal expansion of fullerite C60 at helium temperatures
- 2001
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics. - 1063-777X .- 1090-6517. ; 27:3, s. 245-246
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Tidskriftsartikel (refereegranskat)abstract
- The linear thermal expansion of compacted Ar-doped fullerite C60(ArxC60) is investigated at 2–12 K using a dilatometric method. The thermal expansion of ArxC60 is also studied after partial desaturation of argon from fullerite. It is revealed that argon doping resulted in a considerable change of the temperature dependence of the thermal expansion of fullerite. An explanation of the observed effects is proposed.
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| 3. |
- Aleksandrovskii, A.N., et al.
(författare)
-
Thermal expansion of fullerite C60 alloyed with argon and neon
- 2001
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - Woodbury : American Institute of Physics. - 1063-777X .- 1090-6517. ; 27:12, s. 1033-1036
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Tidskriftsartikel (refereegranskat)abstract
- The linear thermal expansion of compacted fullerite C60 alloyed with argon (ArxC60) and neon (NexC60) are investigated by a dilatometric method. The experimental temperature is 2–12 K. In the same temperature interval the thermal expansion of ArxC60 and NexC60 are examined after partial desaturation of the gases from fullerite. It is found that Ar and Ne alloying affects the temperature dependence of the thermal expansion coefficient of C60 quite appreciably. The libration and translation contributions to the thermal expansion of pure C60 are separated. The experimental results on the thermal expansion are used to obtain the Debye temperature of pure C60. The effects observed are tentatively interpreted.
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| 4. |
- Aleksandrovskii, A. N., et al.
(författare)
-
Thermal expansion of single-crystal fullerite C60 at helium temperatures
- 2000
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 26:1, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- The thermal expansion of single-crystal fullerite C60 has been studied in the range of liquid-helium temperatures (2–10 K). At temperatures below ~4.5 K the thermal expansion of fullerite C60 becomes negative, in agreement with the previous results on polycrystalline materials. A qualitative explanation of the results is proposed.
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