Friction-induced formation of nanocrystals on Si

This paper reports friction-induced formation of nanocrystals on single crystal substrate. Using a pin-on-disk tribometer, a low-melting temperature gallium was slid against single crystal silicon. High resolution TEM results showed that instead of wear, nanometer length scale silicon crystal was formed. The frictional work, eutectic potential, and strain energy density were estimated. There was sufficient frictional energy to melt gallium (Ga) and reach the Ga-Si eutectic temperature. Although it has been reported that friction stimulation induces phase transformation, this work demonstrated the formation of potentially useful nanocrystals, which arose from silicon substrate.