Compilation and characterization of the visual appearance of alkali metal graphite intercalation compounds

Abstract

Graphite intercalation compounds (GICs) have been extensively studied, however, their visual appearance has not been systematically documented, and this plays a crucial role in understanding their physical properties and evaluating their potential applications. Alkali metal GICs (Li-, Na-, K-, Rb-, and Cs-GICs), which are known for their vivid gold and blue colors, were synthesized using a common host graphite under standardized conditions. Photographs were taken under controlled settings to capture their visual appearance, and reflectance spectra were measured to provide optical data, thereby contributing to a standardized color sample compilation. In addition, their structures and electrical conductivities, as well as the relationship between the crystallinity of the host graphite and the perceived appearance of the GICs, were investigated. This study provides a comprehensive reference dataset on GIC appearance, which will support future research on intercalation compounds.