Liquid-state structural asymmetry governs species-selective crystallization in multicomponent systems

TL;DR

This study shows that liquid-state structural asymmetry influences species-selective crystallization in multicomponent systems, with higher-valence ions incorporating more efficiently into the crystal.

Contribution

It reveals that liquid structural asymmetry governs selective incorporation during crystallization, a novel kinetic mechanism affecting multicomponent crystal growth.

Findings

Higher-valence cations form more compatible local environments in liquid.

Species with higher valence are incorporated more efficiently into the crystal.

Experimental measurements support simulation predictions of selective incorporation.

Abstract

Multicomponent crystals are often assumed to form nearly random solid solutions when thermodynamically stable. However, crystal growth proceeds from structurally heterogeneous liquids, raising the possibility that the liquid state may influence which species are incorporated into the growing crystal. Here we demonstrate that liquid-state structural asymmetry can induce species-selective crystallization in multicomponent systems. Using molecular dynamics simulations of a multivalent rocksalt-type model (AgPbBiTe$_3$), we find that cations with higher valence readily form locally crystal-compatible coordination environments in the liquid and are efficiently incorporated into the growing lattice, whereas lower-valence cations exhibit more disordered liquid coordination and attach less efficiently at the crystal-liquid interface. This asymmetry leads to species-selective incorporation and slower crystal growth. Depth-resolved photoelectron spectroscopy measurements on AgPbBiTe$_3$ further reveal enhanced Ag concentration near grain-boundary and surface regions, consistent with the selective incorporation predicted by the simulations. These results demonstrate that structural compatibility between liquid-state structure and the target crystal motif governs selective incorporation during crystallization, providing a general kinetic mechanism by which compositional heterogeneity can emerge during growth of multicomponent crystals.