Local structural disorder in FeCl3–SbCl5-intercalated graphite: revealing the disconnect between long-range periodicity and nanoscale intercalant arrangement

Abstract

Graphite intercalation compounds (GICs) containing metal chlorides exhibit well-defined layer-by-layer periodicity that underlies their electronic and functional properties. However, the local architectures formed during bi-intercalation, particularly in FeCl₃–SbCl₅ graphite bi-intercalation compounds (GBCs), remain largely unexplored. Here, we reveal the nanoscale structural disorder in FeCl₃-GICs and FeCl₃–SbCl₅-GBCs using a combination of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). Well-defined odd-stage FeCl₃-GICs show regular long-range staging, whereas subsequent SbCl₅ intercalation disrupts this periodicity, producing GBCs with heterogeneous local intercalant distributions. Direct lattice imaging by TEM, corroborated by XRD, demonstrates that spatial separation of intercalants stabilizes the bi-intercalated structure. These findings provide new insights into the interaction between long-range order and local disorder, highlighting the importance of nanoscale architecture for understanding and potentially controlling layered intercalation systems.