Connecting the Simpler Structures to Topologically Close-Packed Phases.

Pathways connecting dissimilar crystal structures are fundamental to our understanding of structural phase transitions. In this Letter, we report on a new pathway connecting the hexagonal close-packed crystal structure to a hierarchy of topologically close-packed phases consisting of kagome and triangular nets. Common intermetallic structure prototypes such as the Friauf-Laves phases, CaCu_{5}, Ce_{2}Ni_{7}, Be_{3}Nb, and Co_{7}Gd_{2} are specific members of this hierarchy. We find that the pathway is facile for compounds with large atomic size differences, which has implications for the nucleation mechanism of these complex phases.