ATOMIC-ENVIRONMENT CLASSIFICATION OF THE HEXAGONAL INTERMETALLIC STRUCTURE TYPES

In this paper we give a complete description of the geometrical atomic environments found in the hexagonal intermetallic structure types. Ou r analysis of 442 structure types showed that 315 are possible, while the remaining 127 structure types have e.g. improbable interatomic dis tances or are excluded because they are oxides with no intermetallic c ompounds crystallizing in these structure types. In addition, we obser ved that 23 atomic environment types are greatly preferred. Out of 20 131 point-sets investigated, 16 392 (81%) belong to one of these 23 at omic environment types. Of the 5646 compounds crystallizing in one of the 315 structure types, 14% belong to a single-environment group (str uctures in which all atoms have the same type of environment), 35% com bine two environment types, 32% have three environments, 11% have four environments and the rest (7%) have five or more environments. Our sy stematic and comprehensive analysis of the hexagonal structure types v erified all presently known relationships between these structure type s but also revealed new non-trivial relationships.