| 1. |
- Blank, Vladimir D., et al.
(author)
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High-pressure polymerized phases of C60
- 1998
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In: Carbon. - 0008-6223 .- 1873-3891. ; 36:4, s. 319-343
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Research review (other academic/artistic)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.
(author)
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Carbon nanostructures produced by chlorinating aluminium carbide
- 2001
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In: Carbon. - 0008-6223 .- 1873-3891. ; 39:13, s. 2043-2048
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Journal article (peer-reviewed)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.
(author)
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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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In: Carbon. - 0008-6223 .- 1873-3891. ; 40:9, s. 1559-1564
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Journal article (peer-reviewed)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.
(author)
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Compressibility of C61D2 up to 1 GPa in the temperature range 175 - 345 K
- 1996
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In: Carbon. - : Elsevier Science Ltd.. - 0008-6223 .- 1873-3891. ; 34:9, s. 1119-1121
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Journal article (peer-reviewed)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.
(author)
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Electrical properties of two-dimensional fullerene matrices
- 2001
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In: Carbon. - : Elsevier B.V.. - 0008-6223 .- 1873-3891. ; 39:14, s. 2203-2209
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Journal article (peer-reviewed)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.
(author)
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Magnetism in photopolymerized fullerenes
- 2003
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In: Carbon. - Amsterdam : Elsevier B.V.. - 0008-6223 .- 1873-3891. ; 41:8, s. 1575-1584
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Journal article (peer-reviewed)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.
(author)
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Effect of atomic oxygen on the mechanical properties of highly graphitized carbon fibers
- 1994
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In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 32:4, s. 641-644
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Journal article (peer-reviewed)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.
(author)
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Structural and physical properties of pressure polymerized C60
- 1998
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In: Carbon, vol. 36 issue 5-6. - : Elsevier B.V.. ; 36:5-6, s. 657-660
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Conference paper (peer-reviewed)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.
(author)
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DFT study of the chemistry of sulfur in graphite, including interactions with defects, edges and folds
- 2013
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 62, s. 256-262
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Journal article (peer-reviewed)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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| 11. |
- Anoshkin, Ilya, 1980-, et al.
(author)
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Single walled carbon nanotube quantification method employing the Raman signal intensity
- 2017
-
In: Carbon. - United Kingdom : Elsevier BV. - 0008-6223 .- 1873-3891. ; 116, s. 547-552
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Journal article (peer-reviewed)abstract
- A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.
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| 12. |
- Armakavicius, Nerijus, et al.
(author)
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Resolving mobility anisotropy in quasi-free-standing epitaxial graphene by terahertz optical Hall effect
- 2021
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 172, s. 248-259
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Journal article (peer-reviewed)abstract
- In this work, we demonstrate the application of terahertz-optical Hall effect (THz-OHE) to determine directionally dependent free charge carrier properties of ambient-doped monolayer and quasi-free-standing-bilayer epitaxial graphene on 4H–SiC(0001). Directionally independent free hole mobility parameters are found for the monolayer graphene. In contrast, anisotropic hole mobility parameters with a lower mobility in direction perpendicular to the SiC surface steps and higher along the steps in quasi-free-standing-bilayer graphene are determined for the first time. A combination of THz-OHE, nanoscale microscopy and optical spectroscopy techniques are used to investigate the origin of the anisotropy. Different defect densities and different number of graphene layers on the step edges and terraces are ruled out as possible causes. Scattering mechanisms related to doping variations at the step edges and terraces as a result of different interaction with the substrate and environment are discussed and also excluded. It is suggested that the step edges introduce intrinsic scattering in quasi-free-standing-bilayer graphene, that is manifested as a result of the higher ratio between mean free path and average terrace width parameters. The suggested scenario allows to reconcile existing differences in the literature regarding the anisotropic electrical transport in epitaxial graphene.
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| 13. |
- Asanou, I. P., et al.
(author)
-
Graphene nanochains and nanoislands in the layers of room-temperature fluorinated graphite
- 2013
-
In: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 59, s. 518-529
-
Journal article (peer-reviewed)abstract
- Intercalated compound of graphite fluoride with n-heptane has been synthesized at room temperature using a multi-stage process including fluorination by a gaseous BrF3 and a set of intercalant exchange reactions. It was found that composition of the compound is CF0.40(C7H16)(0.04) and the guest molecules interact with the graphite fluoride layers through the van der Waals forces. Since the distance between the filled layers is 1.04 nm and the unfilled layers are separated by similar to 0.60 nm, the obtained compound can be considered as a stack of the fluorinated graphenes. These fluorinated graphenes are large in area making it possible to study local destruction of the a conjugated system on the basal plane. It was shown that fluorine atoms form short chains, while non-fluorinated sp(2) carbon atoms are organized in very narrow ribbons and aromatic areas with a size smaller than 3 nm. These pi electron nanochains and nanoislands preserved after the fluorination process are likely responsible for the value of the energy gap of the compound of similar to 2.5 eV. Variation in the size and the shape of pi electron regions within the fluorinated graphene layers could be a way for tuning the electronic and optical characteristics of the graphene-based materials.
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| 14. |
- Barzegar, Hamid Reza, et al.
(author)
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Palladium nanocrystals supported on photo-transformed C-60 nanorods : effect of crystal morphology and electron mobility on the electrocatalytic activity towards ethanol oxidation
- 2014
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 73, s. 34-40
-
Journal article (peer-reviewed)abstract
- We report on the synthesis and decoration of high-aspect-ratio crystalline C-60 nanorods (NRs) by functionalized palladium nanoparticles with an average size of 4.78 +/- 0.66 nm. In their pristine form, C-60 NRs suffer from partial damage in the solution-based decoration process resulting in poor crystallinity. However, by modifying the NR surface via in situ photochemical transformation in the liquid state, we are able to prepare highly stable NRs that retain their crystalline structure during the decoration process. Our method thus opens up for the synthesis of highly crystalline nanocomposite hybrids comprising Pd nanoparticles and C-60 NRs. Bys measuring the electron mobility of different C-60 NRs, we relate both the effect of electron mobility and crystallinity to the final electrocatalytic performance of the synthesized hybrid structures. We show that the photo-transformed C-60 NRs exhibit highly advantageous properties for ethanol oxidation based on both a better crystallinity and a higher bulk conductivity. These findings give important information in the search for efficient catalyst support.
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| 15. |
- Battie, Yann, et al.
(author)
-
Mild covalent functionalization of single-walled carbon nanotubes highlighted by spectroscopic ellipsometry
- 2016
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 96, s. 557-564
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Journal article (peer-reviewed)abstract
- Single-walled carbon nanotubes (SWCNT) synthesized using the HiPco® process and purified thereafter were submitted to two covalent functionalization processes: i) a mild oxidation in a concentrated HNO3 solution using microwave irradiation and ii) a radical functionalization to graft methoxyphenyl groups. The samples were analyzed by Raman spectroscopy and spectroscopic ellipsometry in the energy window 0.07-4.96 eV. The complex dielectric function was analytically calculated in order to extract the real (εr) and imaginary (εi) parts of this function vs. the incident energy of the light. The ellipsometric data in the infrared part of the spectrum revealed that process i) mainly affected the amorphous carbon deposited on the surface of SWCNTs while process ii) strongly changed the electronic nature of the film due to a charge transfer between methoxyphenyl groups and SWCNTs. These results demonstrate the richness of information that spectroscopic ellipsometry is able to bring about on an entire carbon nanotube ensemble compared to Raman spectroscopy, while not suffering from limitation on their electronic structure and/or aggregate state/presence of surfactants.
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| 16. |
- Bhattacharya, K., et al.
(author)
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Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant
- 2015
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 91, s. 506-517
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Journal article (peer-reviewed)abstract
- Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H2O2 + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV-Vis-NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H2O2 + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant 'bio-corona' and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.
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| 17. |
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| 18. |
- Bouhafs, Chamseddine, et al.
(author)
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Multi-scale investigation of interface properties, stacking order and decoupling of few layer graphene on C-face 4H-SiC
- 2017
-
In: Carbon. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0008-6223 .- 1873-3891. ; 116, s. 722-732
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Journal article (peer-reviewed)abstract
- In this work, we report a multi-scale investigation using several nano-, micro and macro-scale techniques of few layer graphene (FLG) sample consisting of large monolayer (ML) and bilayer (BL) areas grown on C-face 4H-SiC (000-1) by high-temperature sublimation. Single 1 x 1 diffraction patterns are observed by micro-low-energy electron diffraction for ML, BL and trilayer graphene with no indication of out-of-plane rotational disorder. A SiOx layer is identified between graphene and SiC by X-ray photoelectron emission spectroscopy and reflectance measurements. The chemical composition of the interface layer changes towards SiO2 and its thickness increases with aging in normal ambient conditions. The formation mechanism of the interface layer is discussed. It is shown by torsion resonance conductive atomic force microscopy that the interface layer causes the formation of non-ideal Schottky contact between ML graphene and SiC. This is attributed to the presence of a large density of interface states. Mid-infrared optical Hall effect measurements revealed Landau-level transitions in FLG that have a square-root dependence on magnetic field, which evidences a stack of decoupled graphene sheets. Contrary to previous works on decoupled C-face graphene, our BL and FLG are composed of ordered decoupled graphene layers without out-of-plane rotation. (C) 2017 Elsevier Ltd. All rights reserved.
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| 19. |
- Chen, Xin, et al.
(author)
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PAI-graphene : A new topological semimetallic two-dimensional carbon allotrope with highly tunable anisotropic Dirac cones
- 2020
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In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 170, s. 477-486
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Journal article (peer-reviewed)abstract
- Using evolutionary algorithm for crystal structure prediction, we present a new stable two-dimensional (2D) carbon allotrope composed of polymerized as-indacenes (PAI) in a zigzag pattern, namely PAI-graphene whose energy is lower than most of the reported 2D allotropes of graphene. Crucially, the crystal structure realizes a nonsymmorphic layer group that enforces a nontrivial global topology of the band structure with two Dirac cones lying perfectly at the Fermi level. The absence of electron/hole pockets makes PAI-graphene a pristine crystalline topological semimetal having anisotropic Fermi velocities with a high value of 7.0×105" role="presentation"> m/s. We show that while the semimetallic property of the allotrope is robust against the application of strain, the positions of the Dirac cone and the Fermi velocities can be modified significantly with strain. Moreover, by combining strain along both the x- and y-directions, two band inversions take place at Γ" role="presentation"> leading to the annihilation of the Dirac nodes demonstrating the possibility of strain-controlled conversion of a topological semimetal into a semiconductor. Finally we formulate the bulk-boundary correspondence of the topological nodal phase in the form of a generalized Zak-phase argument finding a perfect agreement with the topological edge states computed for different edge-terminations.
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| 20. |
- Chernova, E. A., et al.
(author)
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The role of oxidation level in mass-transport properties and dehumidification performance of graphene oxide membranes
- 2021
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 183, s. 404-414
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Journal article (peer-reviewed)abstract
- Here we report on gas and vapor transport properties of ultra-thin graphene oxide (GO) membranes, with various C:O ratios. Graphene oxide nanosheets with an average lateral size of 800 nm and C:O ratio ranging from 2.11 to 1.81 have been obtained using improved Hummers' method by variation of graphite:KMnO4 ratio. Thin-film selective layers based on the obtained graphene oxide have been spin-coated onto porous substrates. To extend the C:O range to 2.60, thermal reduction of GO membranes was applied. A decrease in C:O ratio leads to significant water vapor permeance growth to over 60 m(3)(STP).m(-2).bar(-1).h(-1) while the permeance towards permanent gases reduces slightly. According to the permeation and sorption measurements, a decisive role of H2O diffusivity has been established, while the water sorption capacity of the graphene oxide stays nearly independent of C:O ratio in GO. The result is supported by semi-empirical modeling which reveals diminution of H2O jump activation barriers with both increasing GO interlayer spacing and its oxidation degree. The height of the activation barriers was found to vary up to an order of magnitude within the entire range of relative humidity (0-100% RH), lowering significantly for strongly oxidized GO. Our results evidence the necessity of attaining maximum GO oxidation degree for improving water transport in GO, especially at low partial pressures.
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| 21. |
- Chua, C., et al.
(author)
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Observation of Coulomb blockade in nanostructured epitaxial bilayer graphene on SiC
- 2017
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 119, s. 426-430
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Journal article (peer-reviewed)abstract
- We study electron transport in nanostructures patterned in bilayer graphene patches grown epitaxially on SiC as a function of doping, magnetic field, and temperature. Away from charge neutrality transport is only weakly modulated by changes in carrier concentration induced by a local side-gate. At low n-type doping close to charge neutrality, electron transport resembles that in exfoliated graphene nanoribbons and is well described by tunnelling of single electrons through a network of Coulomb-blockaded islands. Under the influence of an external magnetic field, Coulomb blockade resonances fluctuate around an average energy and the gap shrinks as a function of magnetic field. At charge neutrality, however, conduction is less insensitive to external magnetic fields. In this regime we also observe a stronger suppression of the conductance below T*, which we interpret as a sign of broken interlayer symmetry or strong fluctuations in the edge/potential disorder.
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| 22. |
- Cui, Wen, et al.
(author)
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High pressure and high temperature induced polymerization of doped C60 materials
- 2016
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In: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 109, s. 269-275
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Journal article (peer-reviewed)abstract
- Several metastable doped C60 polymers are synthesized under high pressure and high temperature (1.5GPa, 573K and 2GPa, 700K, respectively), using C60/ferrocene (Fc, Fe(C5H5)2), C60/Ni(OEP) and C60/AgNO3 as starting materials. Raman and IR spectroscopy are used to study the polymerization of these samples after HPHT treatment. It is found that the polymerization degree is always lower than that of pure C60 treated at same conditions, which is attributed to the space limitation by the dopants. We also find that even at same conditions, the three doped materials form different polymeric phases of the doped materials. This is attributed to the unique initial lattice structures and the different degrees of spatial confinement provided by the dopants.
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| 23. |
- Cui, Wen, et al.
(author)
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Pressure induced metastable polymerization in doped C60 materials
- 2017
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In: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 115, s. 740-745
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Journal article (peer-reviewed)abstract
- High pressure Raman studies have been carried out on C60/AgNO3 and C60/Ni(OEP) up to 30 GPa. In both these doped C60 materials, pressure-induced metastable ordered polymers can be observed after pressure release. The results show that both the quenched materials contain chainlike polymers and dimers. We also find that the degree of polymerization is higher in these doped C60 materials than in bulk C60 materials after similar high pressure treatment and that C60/AgNO3 contains a higher fraction of chainlike polymers than C60/Ni(OEP) after decompression from same pressure. The results can be understood by considering the different initial lattice structures of these materials and the confinement effects of the dopants.
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| 24. |
- Cui, Wen, et al.
(author)
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Reversible pressure-induced polymerization of Fe(C5H5)(2) doped C-70
- 2013
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In: Carbon. - : Pergamon-Elsevier Science. - 0008-6223 .- 1873-3891. ; 62, s. 447-454
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Journal article (peer-reviewed)abstract
- High pressure Raman, IR and X-ray diffraction (XRD) studies have been carried out on C-70(Fe(C5H5)(2))(2) (hereafter, "C-70(Fc)(2)") sheets. Theoretical calculation is further used to analyze the Electron Localization Function (ELF) and charge transfer in the crystal and thus to understand the transformation of C-70(Fc)(2) under pressure. Our results show that even at room temperature dimeric phase and one dimensional (1D) polymer phase of C-70 molecules can be formed at about 3 and 8 GPa, respectively. The polymerization is found to be reversible Upon decompression and the reversibility is related to the pressure-tuned charge transfer, as well as the overridden steric repulsion of counter ions. According to the layered structure of the intercalated ferrocene molecules formed in the crystal, we suggest that ferrocene acts as not only a spacer to restrict the polymerization of C-70 molecules within a layer, but also as charge reservoir to tune the polymerization process. This supplies a possible way for us to design the polymerization of fullerenes at suitable conditions.
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| 25. |
- Danilchenko, Boris A., et al.
(author)
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1/f noise and mechanisms of the conductivity in carbon nanotube bundles
- 2011
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In: Carbon. - : Elsevier Ltd. - 0008-6223 .- 1873-3891. ; 49:15, s. 5201-5206
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Journal article (peer-reviewed)abstract
- Experimental results are reported of the investigation of conductivity mechanisms in metallic single-wall carbon nanotube (SWCNT) bundles in a wide temperature range from 4.2 K to 300 K. The temperature dependence of the resistance and noise parameters – the logarithmic slope of the current dependence of noise as well as the normalized current noise – are compared. Remarkable changes in noise characteristics are registered at temperatures typical of the transition from hopping conductivity to Luttinger liquid conductivity and the transition from Luttinger liquid conductivity to diffusion conductivity. In the first transition region, the slope of the normalized noise level of the current changes significantly as a function of temperature. In the region of diffusion conductivity, a stronger variation of the normalized noise level is revealed. These changes in noise properties are correlated with changes in the transport characteristics of SWCNT bundles that allow us to adequately explain the mechanisms of conductivity in the system.
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