In situ probing mechanical properties of individual tungsten oxide nanowires directly grown on tungsten tips inside transmission electron microscope

The mechanical properties of individual tungsten oxide (WO3) nanowires, directly grown onto tungsten scanning tunneling microscopy tips, have been investigated by a custom-built in situ transmission electron microscopy (TEM) measurement system. Young's modulii (E) of the individual WO3 nanowires were measured with the assistance of electric-induced mechanical resonance. The results indicate that E basically keeps constant at diameter larger than 30 nm, while it largely increases with decreasing diameter when diameter becomes smaller than 30 nm. This diameter dependence is attributed to the lower defect density in nanowires with smaller diameter, as imaged by in situ TEM.