A cleaner, sustainable approach for synthesising high purity silicon carbide and silicon nitride nanopowders using macadamia shell waste

In this paper, an innovative approach to synthesise silicon carbide (SiC) and silicon nitride (Si3N4) nanopowders by using macadamia shell waste as a source of carbon is reported. Macadamia shell waste contains very low ash and about 20% fixed carbon and is an attractive source of material together with silica for synthesising high purity SiC and Si3N4 nanomaterials based on carbothermal reduction and nitridation reactions. The size of synthesised nanoparticles was in the range of 20–100 nm. Results confirm the formation of β-SiC nanopowder, and 58% β-Si3N4, 42% α-Si3N4 phases in Si3N4 nanopowder with negligible content of impurities. This sustainable and cleaner approach for synthesising high purity advanced materials like SiC and Si3N4 nanoparticles could be a potential application for macadamia shell agricultural waste.