Synthesis and photoluminescence of amorphous silicon nitride/silica coaxial nanotubes

Coaxial nanotubes, composed of silicon nitride outer wall and silica inner wall, were prepared via a two-step process, firstly synthesizing three-layer silicon nitride–silica–In nanocables and then removing the indium core from nanocables via heating in vacuum. The nanotubes are amorphous and typically have round cross-sections. The outer diameters of nanotubes range from 100 to 300 nm. Photoluminescence measurement show that the nanotubes exhibit a weak ultraviolet emission at 379 nm and a strong visible light emission centered at 622 nm with a shoulder at 578 nm.