Intercalation d'alliages or-potassium et calcium-lithium dans des structures carbonées de basse dimensionnalité

Abstract : Since the discovery in 1926 of the first graphite intercalation compounds containing alkali metals, numerous binary and ternary compounds have been synthesized. In this work, solid-liquid method in alkali metal based molten alloys has been employed to intercalate gold into graphite using potassium as an intercalation vector for opening the van der Waals’s gaps and decreasing the reaction temperature. Then, lithium has been used to assist the intercalation of calcium into B-C-N compounds. X-ray diffraction, ion beam analysis, electron microscopy and associated spectroscopy techniques have been performed to characterize the as-prepared compounds. In the case of graphite-potassium-gold system, three novel ternary first stage intercalation compounds with very different repeat distances (1311, 953 and 500 pm) have been synthesized. The K1.3Au1.5C4 compound, isolated in a reproducible fashion, presents a K-Au-Au-Au-K c-axis stacking sequence for the intercalated sheets. The study of its intercalation mechanism evidenced an intermediate product which chemical formula is K1.6Au0.7C4, with three-layered intercalated sheets. The third compound KAu0.7C4 is metastable and contains in each van der Waals‘s gap two successive layers containing a mixture of gold and potassium. Elsewhere, the intercalation of a Li-Ca alloy into B-C-N host material has been successfully carried out. The ion beam analysis of the pristine B-C-N lead to determine on a same sample the amount of boron, carbon and nitrogen with the corresponding B2C5N formula. The experiments realized on the intercalated compound showed the preservation of the host lattice and the intercalation of 0.6 lithium per calcium atom
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Mélissa Fauchard. Intercalation d'alliages or-potassium et calcium-lithium dans des structures carbonées de basse dimensionnalité. Autre. Université de Lorraine, 2014. Français. ⟨NNT : 2014LORR0140⟩. ⟨tel-01750995⟩

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