In-Plane Density of Potassium Liquid and Liquid-Solid Transitions in Potassium Graphite Intercalation Compounds

Abstract

An x-ray-diffraction study of in-plane structures in K-graphite has revealed a remarkable chemical potential (${\ensuremath{\mu}}_{\mathrm{K}}$) dependence of the in-plane density in pure stages 1 and 2, and some continuous nature of the stage-1 melting transition. A simultaneous growth of intralayer and interlayer correlations of K atoms in stage-1 liquid is observed as ${\ensuremath{\mu}}_{\mathrm{K}}$ approaches the solidification po\'{\i}nt. This transition is weakly first order. A new stacking transition from $\ensuremath{\alpha}\ensuremath{\beta}$ to $\ensuremath{\alpha}\ensuremath{\beta}\ensuremath{\gamma}\ensuremath{\delta}$ K layers in stage-1 solid is also reported.