Structural study and crystal chemistry of the first stage calcium graphite intercalation compound

A novel and efficient synthesis method concerning the preparation of the first stage calcium graphite intercalation compound is provided. It makes use of a reaction between liquid metallic alloy and pyrolytic graphite. From now on it is especially easy to obtain bulk CaC(6) samples. Thanks to such samples, it was possible to study in detail the crystal structure of this binary intercalation compound. It has been entirely specified, so that we know that CaC(6) crystal is rhombohedral and belongs to the R (3) over barm space group with the following parameters: a = 517 pm and alpha = 49.55 degrees. The elemental unit cell contains one calcium atom and six carbon atoms. In this paper, we show also how the various MC(6) Structures evolve according to the size of the intercalated element and to the bond nature that appears in the final compound. CaC(6) is unique, since all the other MC(6) compounds exhibit a hexagonal symmetry. (c) 2005 Published by Elsevier Inc.