Crystal Chemistry of Complex Carbides and Related Compounds

Numerous metal carbides can be discussed in a rather uniform way by means of structural features, mainly characterized by the mode of linking of octahedral and occasionally trigonal prismatic [M6C] groups (M = transition element). From this point of view perovskite carbides (M3M′C, M′ = another transition or A‐group element) and derivatives, β‐Mn carbides (M3M′2C), κ‐carbides, carbides with V3AsC‐ and Cr2AlC type structures and derivatives, η‐carbides (M3M′3C) and carbides having the filled Mn5Si3 type structure will be treated. The high stability of these complex carbides is due to the strong bonding MC and additional bonding of MM′ atoms forming an ordered parent lattice. Besides the interstitial principle of filling of lattice holes (by isolated carbon atoms), substitution with A‐group elements may also take place. Thus in borocarbides extended structural elements occur.