Synthesis of silicon carbide nanowhiskers by microwave heating: Effect of heating temperature

Silicon carbide (SiC) is an attractive material for its excellent properties such as wide band gap, high chemical stability and thermal conductivity. The conventional method for the preparation of SiC is Acheson process, a time and energy consuming process. In this article, demonstration of SiC nanowhiskers synthesis has been done by using microwave heating. Silica and graphite in the ratio 1:3 were mixed in ultrasonic bath, dried on hot plate and cold pressed uniaxially into a pellet die. The pellets were heated by using laboratory microwaves furnace at 1350°C, 1400°C and 1450°C with heating rate of 20°C/min and soaked for 40 minutes. Different characterizations and testing were done to study the effect of heating temperature on the synthesis of SiC nanowhiskers. 1400°C is proved to be the most suitable tempearture for the synthesis of SiC nanowhiskers. β-SiC appeared as the only phase in the x-ray diffraction pattern of SiC nanowhiskers formed at 1400°C with no traces of raw materials. Field emission scanning electron microscopy confirmed the presence of only a negligible amount of graphite or silica in SiC nanowhiskers synthesized at 1400°C. Furthermore, energy dispersive x-ray spectroscopy analysis revealed that only elemental C and Si were present in SiC nanowhiskers synthesized at 1400°C. Meanwhile, photoluminescence spectrum indicated the presence of single β-SiC peak at 440 nm which is associated with band gap of 2.8 eV. Single absorption bands of Si-C bond were detected at 803.5 cm-1 in fourier transform infrared spectrum. SiCNWs produced in this study at 1400°C has good thermal stability with 6% of weight loss, indicates its potentiality for high temperature electronics.