Transmission Electron Microscopy and Theoretical Analysis of AuCu Nanoparticles: Atomic Distribution and Dynamic Behavior

KEY WORDS bimetallic nanoparticles; high resolution electron microscopy; quantum mechan-ics; molecular simulation ABSTRACT Though the application of bimetallic nanoparticles is becoming increasingly im-portant, the local atomistic structure of such alloyed particles, which is critical for tailoring their properties, is not yet very clearly understood. In this work, we present detailed study on the atom-istic structure of Au–Cu nanoparticles so as to determine their most stable configurations and the conditions for obtaining clusters of different structural variants. The dynamic behavior of these nanoparticles upon local heating is investigated. AuCu nanoparticles are characterized by high re-solution transmission electron microscopy (HRTEM) and energy filtering elemental composition mapping (EFECM), which allowed us to study the internal structure and the elemental distribu-tion in the particles. Quantum mechanical approaches and classic molecular dynamics methods are applied to model the structure and to determine the lowest energy configurations, the corre-sponding electronic structures, and understand structural transition of clusters upon heating, sup-ported by experimental evidences. Our theoretical results demonstrate only the core/shell bimetal-lic structure have negative heat of formation, both for decahedra and octahedral, and energeticall