Synthesis, characterization, and manipulation of helical SiO2 nanosprings

Amorphous helical SiO2 nanosprings (80 to 140 nm in diameter and up to 8 microns long) were synthesized with a chemical vapor deposition technique, characterized and manipulated by scanning (SEM) and transmission (TEM) electron microscopy and atomic force microscopy (AFM). The helical nanosprings were observed in the middle of a straight nanowire and were formed by a perturbation during the growth of the straight nanowire. Contraction and expansion of the helical nanosprings were observed under in situ electron beam heating during TEM, as well as bending induced by an AFM tip, suggesting that the helical nanosprings are highly flexible and may have potential applications in nanomechanical, nanoelectronmagnetic devices, and composite materials.