Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA.
Nanoscale. 2013 Jul 21;5(14):6333-7. doi: 10.1039/c3nr01501g. Epub 2013 Jun 12.
Behavior of matter at the nanoscale differs from that of the bulk due to confinement and surface effects. Here, we report a direct observation of liquid-like behavior of a single grain boundary formed by cold-welding Au nanoparticles, 40 nm in size, by mechanical manipulation in situ TEM. The grain boundary rotates almost freely due to the free surfaces and can rotate about 90 degrees. The grain boundary sustains more stress than the bulk, confirming a strong bonding between the nanoparticles. Moreover, this technique allows the measurement of the surface diffusion coefficient from experimental observations, which we compute for the Au nanoparticles. This methodology can be used for any metal, oxide, semiconductor or combination of them.
由于受到限制和表面效应的影响，纳米尺度下物质的行为与大块物质不同。在这里，我们通过原位 TEM 的机械操纵直接观察到由 40nm 大小的冷焊金纳米颗粒形成的单个晶界的液态行为。由于存在自由表面，晶界几乎可以自由旋转，可以旋转 90 度。晶界承受的应力大于整体，这证实了纳米颗粒之间的强结合。此外，该技术允许从实验观测中测量表面扩散系数，我们针对金纳米颗粒进行了计算。这种方法可用于任何金属、氧化物、半导体或它们的组合。
