| 1. |
- Blank, Vladimir D., et al.
(författare)
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High-pressure polymerized phases of C60
- 1998
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Ingår i: Carbon. - 0008-6223 .- 1873-3891. ; 36:4, s. 319-343
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Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- Data from recent experimental studies of C60 under high pressures are collected and analyzed, concentrating on the polymerized states where covalent intermolecular bonds have been formed through treatment of molecular C60 at high pressures and temperatures at or above room temperature. We give an overview of the observed phase transformations and the structures of metastable polymeric phases, both crystalline and disordered, as analyzed under ambient conditions, and we present and discuss a pressure-temperature diagram showing which synthesis conditions result in which final phases in the pressure range up to 20 GPa (200 kbar) and at temperatures up to 2300 K. The physical properties of the various phases are discussed whenever enough data are available. The pressure-temperature stability limits for C60 and the conditions for the transformation of C60 into graphite, diamond and chaoite-type carbon are derived.
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| 2. |
- Leis, J, et al.
(författare)
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Carbon nanostructures produced by chlorinating aluminium carbide
- 2001
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Ingår i: Carbon. - 0008-6223 .- 1873-3891. ; 39:13, s. 2043-2048
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Tidskriftsartikel (refereegranskat)abstract
- A number of carbon samples with different nanostructures such as: amorphous, nanoparticles and turbostratic, were synthesised through the reaction between aluminium carbide and gaseous chlorine at fixed temperatures between 300 and 900 degreesC. The synthesised carbon samples were characterised using high-resolution transmission electron microscopy and X-ray powder diffraction techniques, as well as low temperature nitrogen sorption measurements. The carbon produced at T=300 degreesC was amorphous with a surface area of similar to 1400 m(2) g(-1). At 700 degreesC, a large amount of carbon nanoparticles and with a lower surface area similar to 710 m(2) g(-1) was obtained. At 900 degreesC, mainly a turbostratic carbon with a surface area of similar to 680 m(2) g(-1) was produced.
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| 3. |
- Leis, J, et al.
(författare)
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Catalytic effects of metals of the iron subgroup on the chlorination of titanium carbide to form nanostructural carbon
- 2002
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Ingår i: Carbon. - 0008-6223 .- 1873-3891. ; 40:9, s. 1559-1564
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the reaction temperature and the metals of an iron subgroup on the thermo-chemical treatment of titanium carbide with a chlorine gas and their influence on the carbon structure obtained thereby was studied. Different analytical methods such as porosity measure me tits, X-ray diffraction spectrometry and a high-resolution electron microscopy revealed the catalytic behaviour of the above-mentioned metals. which appeared to support the formation of graphitised carbon at much lower temperatures compared to those needed for the ordinary thermo-chemical chlorination of titanium carbide.
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| 4. |
- Lundin, Anders, et al.
(författare)
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Compressibility of C61D2 up to 1 GPa in the temperature range 175 - 345 K
- 1996
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Ingår i: Carbon. - : Elsevier Science Ltd.. - 0008-6223 .- 1873-3891. ; 34:9, s. 1119-1121
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the bulk modulus K for C61D2 up to 1 GPa in the temperature range 175–343 K. For face-centered cubic C61D2 above 290 K, we find an anomalously low value for K below about 0.15 GPa, possibly indicating pressure-induced changes in the structure. The (extrapolated) zero-p bulk modulus K(0) decreases with increasing T from 6.7 GPa at 175 K to 5.2 GPa at 343 K. A comparison with hypothetical expanded f.c.c. C60 with the same lattice constant shows that K(0) values are similar, indicating that the main intermolecular interactions are still between molecular bellies, not the sidegroups.
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| 5. |
- Makarova, Tatiana L, et al.
(författare)
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Electrical properties of two-dimensional fullerene matrices
- 2001
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Ingår i: Carbon. - : Elsevier B.V.. - 0008-6223 .- 1873-3891. ; 39:14, s. 2203-2209
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Tidskriftsartikel (refereegranskat)abstract
- The electrical properties of two-dimensionally polymerized C60 fullerenes were studied. Fullerene matrices consisting of randomly oriented domains are compared to the highly-oriented rhombohedral phase. The conductivity of the randomly oriented polymers obeys the Arrhenius law and can be described in a multiple trapping model. The oriented phase of polymeric C60 shows a distinct anisotropy in the electrical properties with a metallic-like in-plane conductivity at high temperatures.
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| 6. |
- Makarova, Tatiana L, et al.
(författare)
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Magnetism in photopolymerized fullerenes
- 2003
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Ingår i: Carbon. - Amsterdam : Elsevier B.V.. - 0008-6223 .- 1873-3891. ; 41:8, s. 1575-1584
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Tidskriftsartikel (refereegranskat)abstract
- The phototransformation of bulk C-60 and laser- and electron-beam treatment of C-60 films in air changes their magnetic properties. Nonlinear magnetization is observed only for samples irradiated in the presence of oxygen, while, in the case of pressure-polymerized C-60, oxygen adversely affects the magnetic properties. The contrasting roles of oxygen in these processes are discussed. Magnetic force microscopy shows that laser- and electron-beam irradiation of fullerene films produces magnetic images which are highly correlated with the topographic images.
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| 7. |
- Stark, A.K., et al.
(författare)
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Effect of atomic oxygen on the mechanical properties of highly graphitized carbon fibers
- 1994
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 32:4, s. 641-644
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Tidskriftsartikel (refereegranskat)abstract
- Material degradation is a serious problem for large structural members that operate in low earth orbit for a long time. In order to study how the mechanical properties of the fibers change in this environment, highly graphitized polyacrylonitrile-based high modulus carbon fibers have been exposed to different fluences of atomic oxygen, the dominant atmospheric element in low earth orbit. Tensile tests were performed on these fibers. Young's modulus and tensile strength decreased with increasing exposure to atomic oxygen. Scanning electron microscopy revealed that the surface of the carbon fiber was severely degraded by the atomic oxygen, and this explains the decreases in Young's modulus and tensile strength
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| 8. |
- Sundqvist, Bertil, et al.
(författare)
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Structural and physical properties of pressure polymerized C60
- 1998
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Ingår i: Carbon, vol. 36 issue 5-6. - : Elsevier B.V.. ; 36:5-6, s. 657-660
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Konferensbidrag (refereegranskat)abstract
- We discuss the structural and dynamic properties of C60 polymerized under low-P, low-T conditions, and suggest that the disordered mixed orthorhombic-tetragonal-rhombohedral phases produced under these conditions arise from nucleation of molecular chains in random directions because of the quasi-free molecular rotation under standard reaction conditions in the fcc phase of C60. Polymerization in He gives results qualitatively different from those obtained in other media.
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| 9. |
- Adjizian, J.J., et al.
(författare)
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DFT study of the chemistry of sulfur in graphite, including interactions with defects, edges and folds
- 2013
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 62, s. 256-262
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur has several roles, desirable and undesirable, in graphitization. We perform density functional theory calculations within the local density approximation to define the structures and energetics of sulphur in graphite, including its interactions with point defects and edges, in order to understand its role in the later stages of graphitization. We find sulphur does not cross-link layers, except where there are defects. It reacts very strongly with vacancies in neighbouring layers to form a six coordinate split vacancy structure, analogous to that found in diamond. It is also highly stable at basal edge sites, where, as might be expected, the size and valency of sulfur can be easily accommodated. This suggests a role for sulphur in stabilizing graphene edges, and following from this, we show that sulfur dimers can open, i.e. unzip, folds in graphite rapidly and exothermically.
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| 10. |
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