Comparison of two methods for the synthesis of SiO_{2/SiC nanoparticles

The unique hydrothermal method and traditional sol-gel process for the synthesis of nanometre SiO2/SiC particles were comparatively studied. The sol-gel system consists of phenolic resin, ethyl alcohol (C2H5OH) and tetra-ethoxysilane (TEOS). The C-Si binary gel is obtained after the hydrolysing and drying process. Simultaneously, in the hydrothermal kettle, the Si/C precursor is prepared with glucose as the carbon source and silicon powder as silicon source. Then both the Si/C precursors and the C/Si binary gel were calcinated at 1200ºC for 7 h. The morphology and structure of the final products were characterised by Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron micrograph (SEM), energy dispersive X-ray spectroscopy (EDS) and thermal gravimetric (TG). Compared with the two methods, better crystallised SiO2/SiC nanochains were obtained from the Si/C precursors through the unique hydrothermal method with the average size ranging from 100 to 500 nm. The nanochains were composed of the uniformly dispersed spherical SiO2 particles connected with cubic SiC rods. A vapour-liquid-solid (VLS) mechanism was applied to explain the growth of the nanochains. In addition, by studying the effect of the pH of the solution, the crystallisation of the final chains was promoted when the hydrothermal system tended to be neutral.