Claire Herold

New synthesis routes for donor-type graphite intercalation compounds

Abstract New original donor-type graphite intercalation compounds have been synthesized by chemical or electrochemical means, using two main routes: in the first one, the reactions take place in a molten alkali metal: the second one consists of using molten ionic compounds like molten alkali metal halides or hydroxides. Reactions between pyrographite and a heavy alkali metal in the presence of a small quantity of oxygen give new quasi-binary graphite intercalation compounds with a high alkali metal content. Each intercalated sheet is a double layer of alkali metal. Reaction between graphite and sodium in the presence of oxygen or another strongly electronegative element gives new alkali metal-rich ternary compounds. The intercalated sheets are polylayered. The intercalation of alkali metal salt or hydroxide leads to new graphite intercalation compounds containing ionic species. These compounds have a high alkali metal content and the intercalated sheets are also polylayered. All these new compounds show a high stability in air and in water. Most of them exhibit a strong electrical resistivity anisotropy.

Sodium - Oxygen Graphite Intercalation Compound: XPS, UPS and STM Study

Abstract XPS, UPS and STM are used to characterize a second stage NaOxCy compound. The charge distribution and the cleavage localization are discussed.

Intercalation into graphite of sulphur or selenium with potassium

New first stage ternary graphite-potassium-chalcogen compounds were synthesized. They are very rich in alkali metal : their chemical formulas are close to KC3AX (A = sulphur or selenium). We studie...

Sur l'intercalation du sulfure de potassium dans le graphite : Synthèse, structure et relation avec la structure du sulfure libre

A first stage purple graphite intercalation compound has been successfully synthesized, by heating at 400 °C for 3 days, in a stainless steel reactor and under a very pure argon atmosphere, a pyrographite sample immersed in liquid potassium previously mixed with a very small amount of sulphur. This compound is a ternary graphite-potassium-sulphur phase, with a repeat distance of 875 pm and the chemical formula KS0.25C3. One has shown that its intercalated sheets are three-layered, according to the [K-S-K] stacking. Both potassium planes of each intercalated sheet are hexagonal and epitaxially arranged in comparison with the adjacent graphene planes, but they are superimposed according to the AB sequence. The sulphur atoms occupy partially (50%) the octahedral sites, which appear in the central plane of the intercalated sheet. Moreover, the structure of this intercalated potassium sulphide slice exhibits similarities with the fluorite-like cubic structure of K2S.

Recent Data Concerning the Intercalation of Thallium Alloys into Graphite

Abstract The ternary graphite-potassium-thallium and graphite-rubidium-thallium systems were systematically studied. New compounds were observed, and the c-axis and 2D structures of all the ternary phases were determined and compared.

New Graphite Intercalation Compounds : The Potassium Pnictographitides

Abstract New first stage ternary compounds associating potassium and phosphorous were synthesized in liquid potassium containing a few atomic percent of red phosphorous. The structural arrangement of these alkali metal rich phases was studied by X-Ray diffraction. Electrical measurements parallel and perpendicular to the c-axis were carried out between room temperature and 4.2 K.

New heavy alkali metal-oxygen graphite intercalation compounds

Several new oxygen-M-graphite compounds (where M is Rb or Cs) with general formula MC4nOx (n = 1, 2, 0.1 < x < 0.6), were obtained. X-ray diffraction study has shown that these compounds contain two-layered alkali metal packing between graphitic sheets, di for Rb compounds being 8.82–9.20 A, for CsGICs: 9.60 A. It was shown that in some cases this double-layered stacking can be transformed to the dense monolayered one under high pressure conditions.

Phonon dispersion and low-energy anomaly in CaC6 from inelastic neutron and x-ray scattering experiments

We report measurements of phonon dispersion in CaC

Composés d'intercalation du graphite : Des binaires aux ternaires

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Comparison of the Intercalation into Graphite of Phosphorus-Potassium and Mercury-Potassium Binaries

using inelastic X-ray and neutron scattering. We find good overall agreement, particularly in the 50 meV energy region, between experimental data and first-principles density-functional-theory calculations. However, on the longitudinal dispersion along the