期刊
ACS NANO
卷 8, 期 2, 页码 1886-1892出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn4063825
关键词
unidirectional atomic diffusion; core@shell nanoparticle; in situ X-ray absorption spectroscopy; Cu@Au; dilute substitutional intermetallic
类别
资金
- National Natural Science Foundation of China [11135008, U1232132, 11079032, 11175184]
- National Basic Research Program of China [2012CB825800]
- Foundation for Innovative Research Groups of the National Natural Science Foundation of China [11321503]
- Fundamental Research Funds for the Central Universities [WK2310000026]
Understanding the atomic diffusions at the nanoscale is important for controlling the synthesis and utilization of nanomaterials. Here, using in situ X-ray absorption spectroscopy coupled with theoretical calculations, we demonstrate a so far unexplored unidirectional diffusion from the Au shell to the Cu core in thermally alloying Cu@Au core@shell architecture of ca. 7.1 nm. The initial diffusion step at 423 K is found to be characterized by the formation of a diffusion layer composed of a Au-dilute substitutional CuAu-like intermetallic compound with short Cu Au bond length (2.61 angstrom). The diffusion further happens by the migration of the Au atoms with large disorder into the interior Cu matrix at higher temperatures (453 and 553 K). These results suggest that the structural preference of a CuAu-like compound, along with the nanosized effect, plays a critical role in determining the atomic diffusion dynamics.
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