Large-Scale Synthesis and Mechanism of β-SiC Nanoparticles from Rice Husks by Low-Temperature Magnesiothermic Reduction

Silicon carbide (SiC) nanomaterials have many applications in semiconductor, refractories, functional ceramics, and composite reinforcement due to their unique chemical and physical properties. However, large-scale and cost-effective synthesis of SiC nanomaterials at a low temperature is still challenging. Herein, a low-temperature and scalable process to produce β-phase SiC nanoparticles from rice husks (RHs) by magnesiothermic reduction (MR) at a relative low temperature of 600 °C is described. The SiC nanoparticles could inherit the morphology of biogenetic nano-SiO2 in RHs with a size of about 20–30 nm. The MR reaction mechanism and role of intermediate species are investigated. The result shows that SiO2 is first reduced to Mg2Si in the rapid exothermic process and the intermediate product, Mg2Si, further reacts with residual SiO2 and C to produce SiC. Moreover, the SiC shows considerable electromagnetic wave absorption with a minimum reflection loss of −5.88 dB and reflection loss bandwidth < −5 dB of 1.78 GHz. This paper provides a large-scale, cost-effective, environmental friendly, and sustainable process to produce high-quality β-phase SiC nanoparticles from biomass at a low temperature, which is applicable to functional ceramics and optoelectronics.