Kiani Mehrdad T, Hattar Khalid, Gu X Wendy
Department of Materials Science & Engineering, Stanford University, Stanford 94305, California, United States.
Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque 87123, New Mexico, United States.
ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40910-40916. doi: 10.1021/acsami.0c10664. Epub 2020 Aug 26.
Radiation damage can cause significantly more surface damage in metallic nanostructures than bulk materials. Structural changes from displacement damage compromise the performance of nanostructures in radiation environments such as nuclear reactors and outer space, or used in radiation therapy for biomedical treatments. As such, it is important to develop strategies to prevent this from occurring if nanostructures are to be incorporated into these applications. Here, transmission electron microscope ion irradiation was used to investigate whether a metallic glass (MG) coating mitigates sputtering and morphological changes in metallic nanostructures. Dislocation-free Au nanocubes and Au nanocubes coated with a Ni-B MG were bombarded with 2.8 MeV Au ions. The formation of internal defects in bare Au nanocubes was observed at a fluence of 7.5 × 10 ions/cm (0.008 dpa), and morphological changes such as surface roughening, rounding of corners, and formation of nanofilaments began at 4 × 10 ions/cm (0.04 dpa). In contrast, the Ni-B MG-coated Au nanocubes (Au@NiB) showed minimal morphological changes at a fluence of 1.9 × 10 ions/cm (0.2 dpa). The MG coating maintains its amorphous nature under all irradiation conditions investigated.
与块状材料相比，辐射损伤在金属纳米结构中会造成更多的表面损伤。位移损伤导致的结构变化会损害纳米结构在核反应堆和外层空间等辐射环境中的性能，或者在生物医学治疗的放射治疗中使用时的性能。因此，如果要将纳米结构应用于这些领域，开发防止这种情况发生的策略就很重要。在此，使用透射电子显微镜离子辐照来研究金属玻璃（MG）涂层是否能减轻金属纳米结构中的溅射和形态变化。用2.8兆电子伏特的金离子轰击无位错的金纳米立方体和涂有Ni-B MG的金纳米立方体。在7.5×10离子/厘米²（0.008 每原子位移损伤）的注量下，观察到裸露的金纳米立方体中出现内部缺陷，在4×10离子/厘米²（0.04 每原子位移损伤）时开始出现表面粗糙、角部变圆和纳米丝形成等形态变化。相比之下，涂有Ni-B MG的金纳米立方体（Au@NiB）在1.9×10离子/厘米²（0.2 每原子位移损伤）的注量下形态变化最小。在所研究的所有辐照条件下，MG涂层都保持其非晶态性质。
