The interlayer structure of a graphite–potassium–ammonia intercalation compound by neutron diffraction

The out-of-plane structure of the graphite intercalation compound C24K(NH3)4.3 has been determined by time-of-flight neutron diffraction. Isotopic substitution of D for H and 15N for ∗N enables us to locate unambiguously all the intercalated species. The nitrogen atoms are found close to the mid-plane of the interlayer region. We resolve three broad peaks in the proton density, consistent with hindered rotation of the ammonia molecules about their (tilted) C3 axes. More surprisingly, we show that the interlayer potassium ions are located in two peaks adjacent to the graphite sheets, rather than at the mid-plane.