Sc2B1.1C3.2, a New Rare-Earth Boron Carbide with Graphite-like Layers

A Sc-based boron carbide Sc2B1.1C3.2 with a two-dimensional graphite-like framework has been synthesized by a solid state chemical reaction route. Crystals have been grown successfully and the crystal structure could be assigned to represent a new structure type of rare-earth boron carbides. The trigonal crystal structure (a=b=23.710(9) ?, c=6.703(2) ?, P m1 (No. 164)) is composed of alternate –[B1/3C2/3]infinity –Sc–C–Sc–[B1/3C2/3]infinity – layers. The boron and carbon atoms –[B1/3C2/3] infinity – form a significantly puckered graphite-like layer in a rather disordered way. The Sc–C–Sc units appear to be rather loosely accommodated between the [B1/3C2/3]infinity units. Sc–Sc distances show a very close metal–metal contact. In the Sc–C–Sc units carbon atoms are surrounded by six Sc atoms in the form of a slightly distorted octahedron.