Structure-dependent oxidation behavior of Au-Cu nanoparticles

• Published in: Journal of alloys and compounds Vol. 976; p. 173179
• Main Authors: Li, Feitao, Tan, Xinu, Flock, Dominik, Oliva-Ramírez, Manuel, Wang, Dong, Qiu, Risheng, Schaaf, Peter
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.03.2024
• Subjects: Anisotropic and isotropic diffusion; Arrhenius equation; Au-Cu nanoparticles; Disorder-order transformation; Solid-state dewetting; Arrhenius equation; Solid-state dewetting; Anisotropic and isotropic diffusion; Disorder-order transformation; Au-Cu nanoparticles
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.173179

Thermal oxidation is an easily controlled method to change the physical and chemical properties of nanoparticles, thus optimizing and expanding their applications. Unfortunately, less attention has been paid to the role of the crystal structure whose atomic arrangements can be critical for oxidation. Au-Cu nanoparticles showing a fast order-disorder transformation are oxidized at two temperatures of ordered (L10) and disordered (A1) phase regions. The oxidation rates between the two phases are compared by the Arrhenius equation, and a lower oxidation rate is determined in the L10 lattice than in the A1 lattice based on the time required for the complete oxidation. One possible reason is attributed to the longer diffusion length in the L10 lattice compared to the A1 lattice due to the anisotropic diffusion path of the former while isotropic diffusion of the latter, resulting in longer oxidation time and then slower oxidation for the ordered sample. The crystalline phase of Au-Cu nanoparticles can be straightforwardly tuned and the resulting atomic disposition is a powerful tool to control oxidation evolution. [Display omitted] •Au-Cu nanoparticles show a fast and reversible order-disorder (L10-A1) transformation.•Fast ordering kinetics is from the existence of ordered domains in disordered lattice.•Kirkendall voids nucleate at triple junctions and grow along the metal/SiO2 interface.•Isotropic diffusion in the A1 phase while anisotropic diffusion in the L10 phase.•Longer diffusion path in the L10 lattice, leading to slower oxidation than the A1 phase.