Metal catalysts are widely used for nanowire (NW) growth and are one of the essential parameters that dictate the crystal growth phenomena, thus controlling the NW's morphology. Although extensive research has been conducted on catalyst effects, the catalyst drifting effect is generally underestimated for controlling the morphology of nanostructures grown at a relatively high temperature. In this paper, we report a discovery of Zn cluster drifting phenomenon during ZnO vapor deposition. Because of the deposition of ZnO along the drifting path, the dynamic process of cluster drifting could be visualized after the growth. This phenomenon provides a sound explanation of the formation of randomly orientated ZnO nanowall networks. The cluster drifting direction could be intentionally directed by designing the surface inclination, through which a partially parallel aligned ZnO vertical nanofin array was created. This 3D nanoarchitecture would possibly provide a novel configuration for designing high performance integrated nanodevices. The drifting of Zn clusters could be a general phenomenon for most metal catalysts and would provide a new insight into nanofabrication and nanodevice development.

Silica glass exhibits rate-dependent and irreversible processes during deformation and failure, resulting in inelastic effects. To explore this phenomena, molecular dynamics simulations of structural relaxation surrounding a crack tip in silica glass were performed at four different temperatures (100, 300, 600, 900 K) using a reactive force field. Per-atom stresses were found to relax during the simulation, with the highest stress relaxation occurring at 900 K. Stress relaxation was radially dependent relative to the crack tip, with stress dissipation occurring primarily within a 25-30 Å inelastic region. Within 10 Å of the crack tip, the defect concentration decreased from 0.18 to 0.09 #/nm 2 during inelastic relaxation at 900 K. Conversely, the defect concentration 20 Å from the crack tip increased from 0.105 to 0.118 #/nm 2 at 300 K, and from 0.113 to 0.126 #/nm 2 at 600 K, which formed a defect-enriched region ahead of the crack tip. The difference in defect concentrations suggests the possibility of a stress mediated defect migration mechanism, where defects move away from the crack tip during inelastic relaxation. Additionally, defect speciation indicated that undercoordinated silica defects, such as non-bridging oxygen, were removed through the formation of higher coordination defects during relaxation. Overall, stress relaxation causes changes in the defect concentration profile near the crack tip, which has the potential to alter the properties of silica glass in the inelastic region during relaxation.

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