STRUCTURAL AND ELECTRONIC PROPERTIES OF POTASSIUM HYDROGEN INTERCALATED GRAPHITE

Because of the difference in charge transfer and superlattice formation of the various intercalant species, graphite intercalation compounds (GICs) exhibit a variety of interesting electronic properties and phonon properties. These compounds form monolayered metallic superlattices along the c—axis, in contrast to the multilayered metallic superlattices grown from MBE and sputtering synthesis methods. GICs are generally divided into donor—type and acceptor—type compounds, depending on whether the electrons are transferred to the graphite or from the graphite. The modification of the electronic energy bands of GICs by charge transfer is analogous to that of the nipi superlattices. Because of the strong electron affinity of hydrogen relative to that of graphite, the addition of hydrogen into donor—type GICs (e.g. K—GICs, KHg—GICs) modifies the charge transfer from the intercalates to the graphite л-bands. Therefore, studies of the donor—type KHx—GICs provide us with new understanding of the variation of the electronic properties of alkali—metal GICs as the as charge transfer is modified.