Observation of nonhexagonal superlattices in high-stage cesium intercalated graphite

Using a scanning transmission electron microscope with an electron beam size of ∼800 Å, we have found that unsaturated cesium intercalated graphite at 98±2 K exhibits multiple structural phases with a typical domain size of ∼1 μm. Electron diffraction patterns from individual structural islands were studied, and the $p(2\mathrm{}\times 2)$, $p(\sqrt{3}\times 2)$, and $p(\sqrt{3}\times \sqrt{13})$ in-plane superlattices were identified.