Synthesis of one-dimensional nanostructures—β-SiC nanorods with and without amorphous SiO2 wrapping layers

Abstract

Synthesis of one-dimensional nanostructures—β-SiC nanorods with and without amorphous SiO2 wrapping layers–was achieved by controlling carbothermal reduction of sol-gel derived silica xerogels with carbon nanoparticles embedded in the network. The β-SiC nanorods with amorphous SiO2 wrapping layers were obtained by carboreduction at 1650 °C for 1.5 hours and then heating at 1800 °C for 30 minutes. The composite nanorods are typically up to 20 µm in length. The diameters of the center, thinner β-SiC nanorods are in the range of 10 to 30 nm while the outside diameters of the corresponding amorphous SiO2 wrapping layers are between 20 and 70 nm. Monolithic β-SiC nanorods were produced by only carbothermal reduction at 1650 °C for 2.5 hours. The diameters of the monolithic β-SiC nanorods are in agreement with those at the center of the thinner β-SiC nanorods wrapped up in amorphous SiO2 layers. The large quantities of SiC rod nuclei and the nan-ometer-sized nucleus sites on carbon nanoparticles are favorable to the formation of much thinner β-SiC nanorods. The formation of the outside amorphous SiO2 wrapping layer is due to the combination reaction of decomposed SiO vapor and O2 during cooling. The monolithic β-SiC nanorods may be used as reinforcing and toughening elements in ceramic, metal, and polymer matrix nanocomposites. The β-SiC nanorods with amorphous SiO2 wrapping layers might offer opportunities for both fundamental research and technological applications.