Silicon dioxide nanotubes prepared by anodic alumina as templates

Aligned slicon dioxide nanotubes with diameters of 30–40 nm synthesized by the sol-gel template method are presented. This process involves the growth of nanotubes from ordered nanochannel-array pores in anodic alumina. For a silica sol aged at room temperature and dipped for 1 min, nanowires were formed in a shorter period of aging time (2 days); nanotubes connecting with solid nanofibers were obtained in a longer aging time (30 days). The formation of nanotubes depends strongly on the temperature of the sol. For a short dipping time (<1 min), bamboolike nanofibers were prepared when the sol was at high temperature (50 °C); however, perfect nanotubes with the sharp wall were synthetized for the lower sol temperature (5 °C). The lower sol temperature is, the smoother the inside wall of nanotubes is. It is proved that viscosity plays an important role on the morphology of nanotubes.