Ordering in second stage alkali-metal-graphite intercalation compounds

Abstract

The two-dimensional ordering in second stage alkali-metal-graphite intercalation compounds is investigated. It is shown that all hexagonal incommensurate metal lattices form commensurate superlattices. Using this, the observed orientational ordering is modelled by the simple condition that the experimental structure is a superlattice with a local minimum (varying the incommensurate lattice dimension) of the average distance of the metal atom from its nearest graphite hexagon centre. This approach is used in a detailed study of the diffraction pattern of the low temperature phase of second stage rubidium graphite.