Structure and Phase Transitions in Bromine and Potassium-Mercury Intercalated Graphite.

摘要

High resolution x-ray scattering and electron microscopy results relevant to the in-plane structure of two prototype graphite intercalation compound (GIC) systems, Br2-GIC and KHgx-GIC, are presented. Particular emphasis is given to intercalation kinetics and to structural coherence. Of special interest is the measurement using high resolution x-ray scattering of an intrinsic in-plane intercalate domain size in Br2-GIC larger than 10,000. Evidence is presented for the formation of a two-dimensional incommensurate domain wall structure for the Br2 intercalant along the 7-fold direction above T sub C = 69.08 C for stage 4 C28Br2. Evidence is also presented in the same compound for two-dimensional anisotropic melting at T sub M = 100.25 C. Large dislocation-free regions (100 a x 500 a) are observed directly in the lattice fringe images of a stage 1 KHg-GIC sample.