Successive stages of a graphite-potassium compound and its thermal expansion

Abstract

GRAPHITE and potassium amalgamate easily, resulting in golden crystals, and the colour changes to brown, then to dark blue as the potassium is driven off by heating. Schleede and Wellmann1 analysed two stable forms of the lamellar compounds with intercalated potassium atoms in one and two graphite layers respectively. Later, higher stages up to five were analysed2 with the less controllable compounds of graphite-sulphuric acid. Quite recently, Hooley3 proposed a sealed-edge theory to account for the stepwise formation of the compounds concerned. I have also been interested in this point and have performed some experiments which will be described here. © 1962 Nature Publishing Group.