Thermal and Physical Properties of Graphite Intercalation Compounds.

Abstract

Abstract : Five major contributions to research in graphite intercalation compounds (GIC's) have been made. They are (1) the discovery of superconductivity in the mercurographitides (KHgC8 and RbHgC8) which was first seen in low temperature specific heat (Cp) studies, (2) that low-energy phonon states appear to play a role in suppressing Tc for superconducting GIC's and may suppress superconductivity altogether, (3) the re-awakening of interest in magnetic graphite intercalation compounds arising in part from our specific heat studies which suggest the possibility of a magnetic spin-glass state in FeCl3 and NiCl2 compounds, and (4) the confirmation that a low density of electronic states is common to a wide class of acceptor intercalation compounds. In addition, (5) it permitted completion of research that showed for the first time the university of 'twin' phase transitions in donor alkali metal GIC's below stage 1. Of the above, (1), (3) and (5) have led to a wealth of further research by other groups in recent years and have had lasting influence in this research area. Research performed under this grant was devoted primarily to the determination of the low temperature physical properties of a wide range of graphite intercalation compounds (GIC's) and the interpretation of these properties. In addition some new GIC's were synthesized and transport studies initiated elsewhere were completed.