Synthesis, characterization, and photoluminescence properties of bulk-quantity β-SiC/SiOx coaxial nanowires

The bulk-quantity synthesis of coaxial nanowires consisting of a β-phase silicon carbide (β-SiC) core and a silicon oxide (SiOx) shell has been achieved through a rapid and low-cost microwave heating method. In the preparation process, only silicon, silica, and graphite powders were used, without any metal catalysts or inert protective gas. The microstructures and optical properties of β-SiC/SiOx nanowires have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), transmission electron microscopy (TEM), and photoluminescence (PL) measurements at room temperature. The nanowires have lengths of several dozens of micrometers and diameters of 20–30 nm, with SiOx shells exhibiting approximately 30 nm in thickness. They have a growth direction along the <111> planes, with the vapor solid (VS) growth mechanism. The PL spectra, employing a Xe laser (325 nm) as an excitation source, show two emission bands centered at about 444 and 470 nm. The blue-shift phenomenon can be explained by the interface defects and oxygen vacancy defects in the coaxial nanowires.