Highly oriented pyrolytic graphite (HOPG) treated with sodium hydroxide solution was found to show an X-ray diffraction pattern characteristic of a stage-8 intercalation compound. Superstructures such as 2 X 2, √3 X √3 and noble orthorhombic lattices were observed on the NaOH-treated graphite surfaces by scanning tunneling microscopy, as was previously observed on stage-1 alkali-metal graphite intercalation compound (GIC) surfaces formed by Li, K, Rb and Cs intercalates. The orthorhombic phase has a periodic structure formed by four bright and two dark rows, which were explained by the intercalant arrangement occupying two different sites, in the GIC.
Miyake, Koji; Yoshiaki, Aiso; Komiyama, Makoto; and Shigekawa, Hidemi
"Superstructures of Graphite Intercalation Compound Formed by Sodium-Hydroxide Solution Studied by Scanning Tunneling Microscopy,"
Scanning Microscopy: Vol. 8
, Article 3.
Available at: https://digitalcommons.usu.edu/microscopy/vol8/iss3/3