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The authors report the preparation of silica nanotubes by a simple two-stage thermal evaporation of ZnSe and SiO powders. Firstly, nanocables with single crystalline ZnSe nanowire cores and amorphous SiO2 shells were formed by a combined vapor-liquid-solid and SiO-assisted growth process. The ZnSe cores were then evaporated at high temperatures leaving behind SiO2 nanotubes. As-fabricated SiO2 nanotubes were studied with scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopic analysis, and photoluminescence measurement. The SiO2 nanotubes were found to be amorphous, diameter uniform, smooth, and rigid. This method can be used to prepare other materials and morphology-controlled nanotubes. [ABSTRACT FROM AUTHOR]

Nanometer-sized coaxial cables with a single-crystal ZnS core and a thin amorphous SiO2 shell were synthesized by simple thermal evaporation in vacuum. As-fabricated ZnS/SiO2 nanocables were studied using scanning electron microscopy, x-ray diffraction and transmission electron microscopy. The ZnS/SiO2 nanocables have diameters of ∼50 nm, lengths of several tens of micrometers, and shell thickness of ∼4 nm. The core of the nanocable has a wurtzite structure with a growth direction along [001]. The nanocables show strong photoluminescence with two peaks related to band gap and defect-related emission. [ABSTRACT FROM AUTHOR]