Interface Nucleus Templating of Modular Intermetallic Morphologies: Chemical Pressure Complementarity, Columnar...

One element of the diversity of intermetallic phases is the formation of complex structures from the assembly of fragments of simpler structures. Recently, we devised the Interface Nuclear Approach as a model for understanding such modular arrangements, in which the intergrowth of different structures is driven by chemical pressure (CP) relief at shared motifs at the domain interfaces, referred to as interface nuclei. In this Article, we present the synthesis, crystal structure, and CP analysis of a new compound that expands on this theme, Y₁₃Ag_42.7Zn_29.7. Its hexagonal structure contains interpenetrating domains based on the CaPd_5+x and EuMg₅ types. The CaPd_5+x-based regions are reminiscent of the lamellar intergrowth structures previously observed in the Y-Ag-Zn system. In Y₁₃Ag_42.7Zn_29.7, however, the domains have a different morphology, forming columns that adopt a hexagonal rod-packing. The geometrical features of the remaining spaces are assigned, using the program GrowDomain, to the cores of trigonal units of the EuMg₅ type, while layers of disordered atoms occur at heights along z where the parent structures are mismatched. At the CaPd_5+x-type/EuMg₅-type interfaces, simple interface nucleus motifs with strong CP-complementarity can be identified, while their distribution within the parent structures supports the notion of templated architectures in modular intermetallics.