Growth and characterization of nanostructured β-SiC via carbothermal reduction of SiO 2 xerogels containing carbon nanoparticles

Abstract

Sol–gel route was used to prepare SiO 2 xerogels containing carbon nanoparticles. Three kinds of β-SiC nanostructures were obtained by carbothermal reduction of the xerogels under different conditions. XRD and IR studies show that the powders, obtained from carbothermal reduction at 1650° for 2.5 h in static argon atmosphere, are β-SiC. TEM reveals that the powders are nanoparticles with diameters ranging from 30 to 100 nm. The specific surface area of the powders are 15.7 m 2/g. TEM, SAED and EDX show that the products, synthesized by carbothermal reduction at 1650°C for 1.5 h, and followed by heating to 1800°C, holding for 30 min in flowing argon atmosphere, are nanowires that consist of 10- to 25-nm-diameter crystalline β-SiC cores surrounded by amorphous SiO 2 sheathes with outer diameters of between 20 and 70 nm. While TEM and SAED demonstrate that the products, formed by carbothermal reduction at 1650° for 2.5 h in flowing argon atmosphere, are bare SiC nanowires with diameters in the range of 15–30 nm.