Synthesis, Characterization, and Structural Modeling of Graphite Intercalation Compounds with Fluoroanions PDF Download

Author: Wei Yan
Publisher:
ISBN:
Category : Graphite intercalation compounds
Languages : en
Pages : 340

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Author: Xuerong Zhang
Publisher:
ISBN:
Category : Graphite intercalation compounds
Languages : en
Pages : 414

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Author: Bahar Ozmen Monkul
Publisher:
ISBN:
Category : Graphite fluorides
Languages : en
Pages : 338

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New acceptor-type graphite intercalation compounds (GICs) containing perfluoroalkyl anions have been synthesized by using both chemical and electrochemical methods and characterized by elemental and thermogravimetric analyses. Investigation into these graphite intercalation compounds can provide novel materials and a detailed understanding of their properties. GICs of composition Cx[FB(C2F5)3]·[delta]F are prepared for the first time by the intercalation of fluoro-tris(pentafluoroethyl)borate anion, [FB(C2F5)3]−, under ambient conditions in aqueous (48 %) hydrofluoric acid containing the oxidant K2[MnF6].Powder-XRD data indicate that products are pure stage 2 and physical mixture of stage 2 and stage 3 after 1 h to 20 h reaction times. The calculated basal repeat distance, Ic, is 1.20 nm for stage 2 and 1.54-1.56 nm for stage 3 GICs, corresponding to gallery heights of di= 0.86-0.89 nm. In addition, stage 2 GIC of Cx[FB(C2F5)3]·[delta]CH3NO2 having di=0.84 nm is prepared by electrochemical oxidation of graphite in a nitromethane electrolyte. The elemental analyses of these complex GICs required that a new sample digestion protocol be developed. After digestion, the fluoride amounts in these GIC samples were analyzed by using ion-selective fluoride combination electrode. The method developed is able to provide fluoride anion content in GICs without interference from the decomposition products of [FB(C2F5)3]- anion. For the boron analyses the same digestion procedure above is used and the B contents were determined by ICP-AES. For Cx[FB(C2F5)3]·[delta]F, both compositional parameters x and [delta] are obtained from the results of elemental B and F analyses. For the chemically prepared GICs at 1 h to 20 h, calculated x values were in the range of 51-56 and the calculated [delta] values increased with reaction time from approx. 0-2. Combining B analysis and TGA mass loss gives a composition of x=44 and [delta]= 0.37 for the electrochemically prepared GIC of Cx[FB(C2F5)3]·[delta]CH3NO2. Energy minimized structure for the isolated borate anion and powder XRD data show that the borate anions adopt a "lying-down" orientation where the long axes of [FB(C2F5)3]- intercalate anions are parallel to the encasing graphene sheets. The same electrochemical synthesis strategy is also used for the preparation of a new acceptor-type GIC containing the cyclo-hexafluoropropane-1,3-bis(sulfonyl)amide anion, [CF2(CF2SO2)2N]−. The gallery heights of 0.85-0.86 nm are determined by powder X-ray diffraction for stage 2 and 3 products. These GICs are obtained by electrochemical oxidation of graphite in a nitromethane electrolyte. GICs containing the linear anion, [(CF3SO2)2N]− are also prepared in order to compare the gallery heights and the electron charge distributions that helps to understand the GIC stabilities within the graphene sheets. The compositions of GICs containing [CF2(CF2SO2)2N]− are determined by thermogravimetric, fluorine and nitrogen elemental analyses. GICs of composition Cx[(C2F5)3PF3] are prepared for the first time by the intercalation of tris(pentafluoroethyl trifluorophosphate (FAP) anion, [(C2F5)3PF3]− by electrochemical oxidation of graphite. Powder-XRD data indicate that products are of stages 2-4 with gallery heights of 0.82-0.86 nm. These GICs are characterized by the same methods using TGA and F ion selective probe analyses.

Author: Hartmut Zabel
Publisher: Springer Science & Business Media
ISBN: 3642752705
Category : Science
Languages : en
Pages : 365

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The progress of materials science depends on the development of novel materials and the development of novel experimental techniques. The research on graphite intercalation compounds combines both aspects: new compounds with strikingly new and anisotropic properties have been synthesized and analyzed during the past couple of years by means of state-of-the-art experimental methods. At the same time, the preparation of the compounds already known has improved con siderably, giving increased reliability and reproducibility of the experimental results. The high quality experimental data now available have stimulated theo retical work. Moreover, the theoretical work has had a great impact on further experimental studies, with the effect of a much improved understanding of this class of materials. This volume is dedicated to a thorough description of all relevant experimen tal and theoretical aspects of the structural and dynamical properties of graphite intercalation compounds. Because of the large number of topics, a second vol ume, which is now in preparation, will follow and will treat the electronic, transport, magnetic, and optical properties. The second volume will also contain a chapter on applications of graphite intercalation compounds. There have been a number of reviews written on selected aspects of these compounds in various journals and conference proceedings during the last couple of years, but this is the first comprehensive review since the thorough overview provided by M.S. Dresselhaus and G. Dresselhaus appeared ten years ago.

Author: Toshiaki Enoki
Publisher: Oxford University Press
ISBN: 9780195351842
Category : Science
Languages : en
Pages : 556

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Graphite intercalation compounds are a new class of electronic materials that are classified as graphite-based host guest systems. They have specific structural features based on the alternating stacking of graphite and guest intercalate sheets. The electronic structures show two-dimensional metallic properties with a large variety of features including superconductivity. They are also interesting from the point of two-dimensional magnetic systems. This book presents the synthesis, crystal structures, phase transitions, lattice dynamics, electronic structures, electron transport properties, magnetic properties, surface phenomena, and applications of graphite intercalation compounds. The applications covered include batteries, highly conductive graphite fibers, exfoliated graphite and intercalated fullerenes and nanotubes.

Author: Watcharee Katinonkul
Publisher:
ISBN:
Category : Graphite fluorides
Languages : en
Pages : 304

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New chemical synthesis strategies have been investigated for the preparation of acceptor-type graphite intercalation compounds (GIC's) with fluoroanions in order to obtain new materials and to develop a better understanding of the synthetic approaches and properties of the products. New GIC's containing borate chelate anion such as bis(oxalato)borate, CxB[OC(O)C(O)O]2[delta]F, are prepared by the chemical oxidation of graphite with fluorine gas in the presence of a solution containing the intercalate anion in anhydrous hydrofluoric acid. Due to the chemical method employed (F2/AHF as the oxidizing agent), fluoride co-intercalates are present in the galleries. The GIC's compositions are determined using a newly-developed digestion method with an ion-selective electrode and potentiometer. The composition parameters x and [sigma] are obtained using both elemental and thermogravimetric analyses (TGA). Elemental analyses of B and F for a stage 1 GIC indicate x [approximately equal to] 41 and [delta] [approximately equal to] 4. Powder XRD data and the structural refinement of these GIC's show that the intercalate anions "stand up" in the galleries, with the longer anion dimension oriented perpendicular to the graphene sheets, leading to the relatively large gallery height of di [approximately equal to] 1.42 nm. The same chemical synthesis strategy is also used for chemical preparations of other two borate chelate GIC's; bis(perfluoropinacolato)borate, CxB[OC(CF3)2C(CF3)2O]2[sigma]F, and bis(hexafluorohydroxyisobutyrato)borate, CxB[OC(CF3)2C(O)O]2[sigma]F. Stage 1 GIC's of these anions are obtained with the gallery height, di, of 1.43-1.45 nm. The fluoride co-intercalate contents in these GIC samples are also determined. The composition parameters x and [sigma] are obtained using elemental analyses for stage 1 CxB[OC(CF3)2C(CF3)2O]2[sigma]F and for stage 1 CxB[OC(CF3)2C(O)O]2[sigma]F. TGA cannot be used to confirm these compositions due to the incomplete degradation of intercalates. Most likely, anions and their degradation products are trapped in the bulk of the large flaky graphite particles. The detailed compositions of GIC's containing bis(trifluoromethanesulfonyl) imide, CxN(SO2CF3)2[sigma]F, and perfluorooctanesulfonate, CxC8F17SO3[sigma]F and fluoride co-intercalates are determined for the first time. These GIC's are prepared in aqueous HF, using K2MnF6 as the oxidizing agent. The fluoride co-intercalate content is approximately equimolar to anion content in both GIC's. For CxN(SO2CF3)2[sigma]F, the fluoride content increases steadily with reaction time while the anion content is relatively constant. In contrast, CxC8F17SO3[sigma]F shows little change in the fluoride content over time.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The compound CxAsF5 was prepared and characterized by x-ray diffraction and x-ray absorption, which show the presence of As(III) and As(V), and the As-F bond distances are consistent with AsF3 and AsF−6, CAsF−6 and C+8OsF−6 were synthesized. The CxAsF6 and numerous standard arsenic-flourine compounds were studied by x-ray absorption. Magnetic susceptibility of C+8OsF−6 confirms the high degree of oxidation in this compound. X-ray absorption studies were begun to determine the species present within the graphite when BrF3 or GeF4 + F2 are added. In the BrF3 case, Br2 is evolved and only Br(III) is present in the graphite. The binary phase diagram XeF2:Xe+5AsF−6 was investigated by melting point determination and Raman spectroscopy. This mixture near 1.3:1 forms a kinetically stable glass at room temperature and is molten at 50°C. Several new species or phases are observed in the Raman spectra. These species have been assigned tentative structures.

Author: Hartmut Zabel
Publisher: Springer My Copy UK
ISBN: 9783642752711
Category :
Languages : en
Pages : 378

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This book covers the basic physics and chemistry of graphite intercalation compounds. Emphasis is laid on the layered or quasi-two-dimensional structure of these compounds, which provides an exciting arena for testing physical concepts in lower dimensions. The chapters in this volume, all of which have been written by internationally recognized experts in the field, cover the following topics: the structure and phase transitions of intercalate atoms and molecules in graphite, the physics of staging formation and staging transitions, the lattice dynamics of these compounds as determined by inelastic neutron scattering and optical methods, the diffusivity of the guest species, mesoscopic properties such as domain structures and stacking arrangements, and the synthesis of new compounds. The reviews provide a comprehensive overview of the current status of the field of two- dimensional physics.

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 902

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Author: Zhengwei Zhang
Publisher:
ISBN:
Category : Graphite intercalation compounds
Languages : en
Pages : 260

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