Structure-Dependent Chemical Order Modification in Strained Alloy Nanoparticles

Alloy nanoparticles (nanoalloys) exhibit tunable physicochemical properties that depend sensitively on atomic arrangement. While most theoretical studies consider nanoalloys in a vacuum, practical systems are typically supported, where strong cluster-substrate interactions can introduce significant lattice strain. Here, we investigate strain as a control parameter for chemical ordering in bimetallic nanoalloys using atomistic simulations. Imposing controlled strain through an implicit anchored interface, we probe the response of NiPt nanoparticles with distinct structural motifs. For truncated-octahedral particles, chemical ordering remains remarkably robust even under large strains, indicating that intrinsic thermodynamic preferences dominate. Conversely, icosahedral nanoparticles exhibit pronounced strain-induced chemical redistribution with a significant increase in surface Ni concentration under tensile strain, attributed to the combined effects of intrinsic geometric frustration and a high fraction of undercoordinated sites. Our results demonstrate that strain can selectively modulate chemical ordering in a structure-dependent manner, establishing a general framework for understanding strain-induced chemical ordering in nanoalloys.