Preparation of a Rhombohedral Boron Carbide of the Composition B sub 13 C sub 2

摘要

NMR and phase studies have led to the conclusion that the central atom of the C sub 3 chain in rhombohedral boron carbide, must actually be a boron atom. An attempt was therefore made to prepare pure boron carbide crystals of the analytic composition B sub 13 C sub 2 . A rhombohedral boron carbide having a carbon content of 15.1 to 15.4 wt % (B sub 13 C/sub 2.08-2.13/) was obtained. The primitive rhombohedral elemental cell of B sub 13 C sub 2 (with B sub 12 icosahedrons at each vertex) is not a C sub 3 chain but a linear CBC chain in the (111) direction. It is probable that B sub 4 C is a solid solution of carbon in B sub 12 CBC(B sub 13 C sub 2 ). (ERA citation 10:010121)