# Interface Nucleus Templating of Modular Intermetallic Morphologies: Chemical Pressure Complementarity, Columnar Domains, and Complex Disorder in Y13Ag42.7Zn29.7

## TL;DR

This paper explores the formation of complex intermetallic structures in Y13Ag42.7Zn29.7, revealing how modular domains are arranged through chemical pressure relief at interface nuclei.

## Contribution

The study introduces a new compound with columnar domain morphology and demonstrates templated architectures via interface nucleus motifs.

## Key findings

- Y13Ag42.7Zn29.7 exhibits a hexagonal structure with interpenetrating CaPd5+x and EuMg5-type domains.
- Interface nuclei at domain boundaries show strong chemical pressure complementarity.
- Disordered atomic layers arise where parent structures are mismatched along the z-axis.

## Abstract

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, Y13Ag42.7Zn29.7. Its hexagonal structure
contains interpenetrating domains based on the CaPd5+x
and EuMg5 types. The CaPd5+x
-based regions are reminiscent of the lamellar intergrowth
structures previously observed in the Y–Ag–Zn system.
In Y13Ag42.7Zn29.7, 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 CaPd5+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.