From the images of HR-TEM, FE-SEM, and AFM, the cold welding of gold nanoparticles (AuNPs) on a mica substrate is observed. The cold-welded gold nanoparticles of 25 nm diameters are found on the mica substrate in AFM measurement whereas the size of cold welding is limited to 10 nm for nanowires and 2~3 nm for nanofilms. Contrary to the nanowires requiring pressure, the AuNPs are able to rotate freely due to the attractive forces from the mica substrate and thus the cold welding goes along by adjusting lattice structures. The gold nanoparticles on the mica substrate are numerically modeled and whose physical characteristics are obtained by the molecular dynamic simulations of LAMMPS. The potential and kinetic energies of AuNPs on the mica substrate provide sufficient energy to overcome the diffusion barrier of gold atoms. After the cold welding, the regularity of lattice structure is maintained since the rotation of AuNPs is allowed due to the presence of mica substrate. It turns out that the growth of AuNPs can be controlled arbitrarily and the welded region is nearly perfect and provides the same crystal orientation and strength as the rest of the nanostructures.

中文翻译：

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金纳米粒子在云母基底上的冷焊：自我调节和增强的扩散。

从HR-TEM，FE-SEM和AFM的图像中，可以观察到金纳米粒子（AuNPs）在云母基底上的冷焊。在AFM测量中，在云母基板上发现了直径为25 nm的冷焊金纳米颗粒，而对于纳米线，冷焊的尺寸限制为10 nm，对于纳米膜，冷焊的尺寸限制为2〜3 nm。与需要压力的纳米线相反，由于来自云母基底的吸引力，AuNPs能够自由旋转，因此通过调节晶格结构进行了冷焊。对云母基底上的金纳米粒子进行了数值建模，并通过LAMMPS的分子动力学模拟获得了其物理特性。云母基底上AuNPs的势能和动能提供了足够的能量来克服金原子的扩散势垒。冷焊后 由于云母基质的存在，允许AuNPs旋转，因此保持了晶格结构的规则性。事实证明，可以任意控制AuNPs的生长，并且焊接区域几乎完美，并提供与其余纳米结构相同的晶体取向和强度。