In-situ synthesis of SiC/SiO2 nanowires by catalyst-free thermal evaporation of silicon powder and their photoluminescence properties

Abstract

Core-shell structured SiC/SiO2 nanowires (SiC/SiO2 NWs) were synthesized by a simple thermal evaporation method without a catalyst. The influence of the growth temperature and holding time on the microstructure and composition of the nanowires were investigated. The results indicate that within the temperature range of 1150 to 1550 °C, the color of SiC/SiO2 nanowires gradually transitions from pure white to off-white with increasing temperature. During this process, the average diameter of SiC/SiO2 increases from ~74 nm to ~291 nm, while the surface SiO2 layer thickness decreases from ~17 nm to ~5 nm, with nanowires can reach lengths of hundreds of micrometres. Variations in supersaturation of SiO and CO at different temperatures lead to discrepancies in nanowire diameter and SiO2 shell thickness. At 1350 °C, prolonged holding time enhances silicon powder reaction, resulting in increased structural disorder of the obtained SiC/SiO2 nanowires. The nanowire growth follows a vapor-solid (VS) mechanism. Additionally, the study demonstrates that the photoluminescence (PL) characteristics of the nanowires exhibit a blue shift attributable to their nanoscale dimensions, while variations in emission spectra correlate with stacking faults, SiC diameter, and SiO2 thickness. This work may be provide a theoretical basis for preparing SiC/SiO2 nanowires with different diameters and SiO2 shell thicknesses, which is crucial for advancing the development and application of SiC/SiO2 nanoceramics.