期刊
SCIENCE
卷 326, 期 5951, 页码 405-407出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.1178179
关键词
-
资金
- NSF [DMR-0807065]
- Robert A. Welch Foundation [F-1464]
- Fannie and John Hertz Foundation
- NSF Graduate Research Fellowship Program
Confined nanoscale geometry greatly influences physical transformations in materials. The electron microscope enables direct visualization of these changes. We examined the evolution of a germanium (Ge) nanowire attached to a gold (Au) nanocrystal as it was heated to 900 degrees C. The application of a carbon shell prevented changes in volume and interfacial area during the heating cycle. Au/Ge eutectic formation was visualized, occurring 15 degrees C below the bulk eutectic temperature. Capillary pressure pushed the melt into the cylindrical neck of the nanowire, and Ge crystallized in the spherical tip of the carbon shell. Solid-state diffusion down the length of the confined Ge nanowire was observed at temperatures above 700 degrees C; Au diffusion was several orders of magnitude slower than in a bulk Ge crystal.
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