An ideal ternary heterostructure graphite intercalation compound, KCs${\mathrm{C}}_{16}$, which exhibits a stage-1 $c$-axis stacking sequence,...CKCCsCKCCs..., has been prepared. The stage, stacking sequence, and $(2\mathrm{}\times 2)R0°$ in-plane structure have been confirmed by high-resolution x-ray diffraction studies which reveal a $c$-axis correlation range of ∼350 Å. The structure factor and widths of the ($00l$) reflections calculated on the basis of the proposed stacking sequence are in excellent agreement with experimental observations.

• Received 28 February 1983

DOI:https://doi.org/10.1103/PhysRevLett.50.1470