Fluid-like Surface Layer and Its Flow Characteristics in Glassy   Nanotubes
  We observed strongly size-dependent viscoelasticity in amorphous SiO2 and Si nanotubes with shell thickness down to ~8 nm. A core-shell model shows that a ~1 nm thick fluid-like surface layer has a significant effect on the mechanical behavior of nanotubes and matches well with our experimental results. Surprising, the surface layer exhibits a room temperature viscosity equivalent to that of bulk glass above 1000 C. Additionally, a low activation energy extracted from temperature dependent creep tests indicates that the viscous flow in the surface layer is due to bond motion/switching, instead of bond breaking. These findings unambiguously show the presence of a fluid-like surface layer and elucidate its role on dynamic mechanical behavior in nanoscale inorganic glass. 
Matthew C. Wingert, Soonshin Kwon, Shengqiang Cai, and Renkun Chen
cond-mat.mtrl-sci