Localization Phenomena and Carrier-Carrier Interaction in Fluorine-Graphite Intercalation Compounds

Vittorio, S.L. di; Dresselhaus, M. S.; Dresselhaus, G.

doi:10.1007/978-94-011-3190-2_1

Cited by 3 publications

(4 citation statements)

References 25 publications

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“…We estimate the strain energy to be a fraction of the bonding energy, i.e., several tens of kcal/mole. A more accurate value for Strain would require a detailed calculation of the overlap of the sp 2 and sp 3 orbitals, taking into account first-and possibly second-neighbor carbon atoms. Indeed, the deformation is not limited to the carbon atom that bonds covalently with the halogen, but is also accommodated by its carbon neighbors.…”

Section: Cf Y Is~f )Ye Ion + Fye Cov E Stnin (Fy) + E M (Fy)mentioning

confidence: 99%

“…(Experimentally, the C 4 F compound is still mostly an ionic solid. 2 ) When the number of sp 3 bonds exceeds the number of sp 2 bonds, the sp 2 bonds can be considered to cause the strain. The strain then decreases with increasing covalent bonding from the halogens, making it highly favorable energetically to form more covalent bonds.…”

Section: Bondmentioning

confidence: 99%

“…However, the high strain also creates a large density of other defects, mainly stacking faults and dislocations. As the fluorine concentration gets close to the ideal C 2 F stoichiometry, the strain due to the mixture of sp 2 and sp 3 bonds recedes, but the stacking faults and the dislocations do not disappear, and neither do the very disordered regions associated with the boundaries between the covalent grains. We attribute the grain boundaries to the different orientations of the buckling between different islands.…”

Section: Application Of the Model To Fluorine And Bromine Gic'smentioning

confidence: 99%

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A model for disorder in fluorine-intercalated graphite

Vittorio

Dresselhaus

1993

J. Mater. Res.

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The structural and electronic properties of fluorine-and bromine-intercalated graphite fibers and HOPG are summarized. In contrast to the bromine intercalate, which is purely ionic for any experimentally attainable intercalate concentration, fluorine has a dual ionic and covalent behavior in graphite. Furthermore, whereas bromine-intercalated graphite is ordered, fluorine-intercalated graphite is disordered. The stiff graphene planes are buckled and islands of various fluorine concentrations are formed. A thermodynamic model is proposed that accounts for the differences between fluorine-and bromine-intercalated graphite materials. The model describes the competition between ionically bonded and covalently bonded intercalate phases of fluorine in graphite. Covalent bonding is more favorable energetically, but an important nucleation barrier exists due to strain and to the destruction of the conjugation of the double bonds.

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Section: Cf Y Is~f )Ye Ion + Fye Cov E Stnin (Fy) + E M (Fy)mentioning

confidence: 99%

Section: Bondmentioning

confidence: 99%

Section: Application Of the Model To Fluorine And Bromine Gic'smentioning

confidence: 99%

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A model for disorder in fluorine-intercalated graphite

Vittorio

Dresselhaus

1993

J. Mater. Res.

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“…A large body of characterization work on (CF x ) n reveals a rich array of localized structural features, including morphological changes, point defects, and polymorphism, , all of which can impart modified C–F bonding character, along with variations of the relative concentration of the CF, CF 2 , and CF 3 environments. These structural differences are influenced or controlled by the original carbon source, the synthesis conditions, and the extent of fluorination. − The modified C–F bond character ranges from covalent, to elongated covalent (also referred to as semi-ionic), , to ionic and is a function of the extent of sp 2 hybridization (i.e., F/C ratio), − lattice curvature, − local fluorine density, − and porosity. − Point defects can also influence C–F bond character and include heteroatom substitution, unsaturated C–C bonds, graphene domains, and ring dislocation …”

Section: Introductionmentioning

confidence: 99%

Impact of Disorder and Defects on Bond Energies in Highly Fluorinated Graphene

2023

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Fluorinated graphite materials are of interest for an assortment of applications and can be synthesized under a variety of synthetic conditions from many different types of carbon. Due to such variations, structural disorders in the form of defects and polymorphism are often present. Here, we investigate the impact of local structural variations on the C–F bond dissociation energies (BDEs) in carbon-based fluoride materials using density functional theory (DFT) computational methods. Employing fluorographene (FG) cluster models, we determine the impact of different C–F bonding configurations in the core of each platelet on the equilibrium BDEs for each C–F bond. The introduction of structural disorder decreases the first C–F BDE by approximately 1 eV compared to the canonical arrangement of axial C–F bonds ordered as in a network of cyclohexane “chairs”. Variability of calculated BDEs among the different polymorphs decreases upon subsequent F removal. Common structural tendencies of the adiabatic defluorination pathways for each polymorph are identified. Our analysis suggests that at F/C ratios near 1.0, disorder in the local structure can play a significant role in the energetics of the initial carbon fluoride defluorination and that the influence of this configurational disorder diminishes with decreasing F/C ratios.

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A second decade of semiconductor heterojunction devices

Kelly

1993

Microelectronics Journal

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Localization Phenomena and Carrier-Carrier Interaction in Fluorine-Graphite Intercalation Compounds

Cited by 3 publications

References 25 publications

A model for disorder in fluorine-intercalated graphite

A model for disorder in fluorine-intercalated graphite

Impact of Disorder and Defects on Bond Energies in Highly Fluorinated Graphene

A second decade of semiconductor heterojunction devices

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