One-step growth of silica nanotubes and simultaneous filling with indium sulfide nanorods

A high temperature approach has been utilized for the mass production of ultra-long, straight silica nanotubes and indium sulfide filled cable-like structures by heating of an Si wafer and In2S3 powder under a stream of hydrogen/argon gases at 950 °C. Transmission electron microscopy, scanning electron microscopy and X-ray diffraction analysis demonstrate the formation of hollow cylindrical amorphous silica tubes with lengths up to hundreds of micrometers and outer diameters in the range of 70 to 300 nm, silica tubes encapsulating indium sulfide nanorods with a cubic structure and S-filled silica tubes with high sensitivity to a focused electron beam. A modified vapor–liquid–solid growth was proposed for the formation of amorphous silica nanotubes under the coexistence of low melting point In and S. The capillary induced filling promoted simultaneous formation of indium sulfide nanorods upon further crystallization.