Synthesis of Silicon Carbide Nanowires from a Hybrid of Amorphous Biopolymer and Sol–Gel-Derived Silica
We report here the formation of silicon carbide (SiC) nanowires from inorganic–organic hybrid of sol–gel-derived silica and the commercially available lignin that is naturally abundant amorphous biopolymer. This organic–inorganic hybrid material in the absence of catalyst was carbothermally reduced for a period of 1 h at 1400°C in inert atmosphere followed by oxidization. The nanostructures were characterized by scanning electron microscopy and high resolution scanning electron microscopy, which show the continuous formation of -SiC nanowires in the range of 50–200 nm diameter and length of few micrometers. Transmission electron microscopy revealed Y-shaped structures (branched) of the nanowires grown in the direction of parallel to the  plane having two heads and one leg. The nanowires were formed with joints that were formed at regular intervals as circular rings. The deposition of silica layer on the outer surface of the nanowires was also observed. According to the X-ray diffraction pattern, peaks at 2=35.9° and 59.8° indicate the formation of -SiC and a sharp peak at 2=22.1° suggests the presence of unreacted crystalline silica (crystoballite). The Raman shifts for -SiC appeared as small peaks at 795.6 and 983.1 cm−1, respectively. The characteristic vibration of SiC at 795 cm−1 in Fourier transform infrared spectroscopy was also observed.
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Document Type: Research Article
Affiliations: Department of Chemical Technology, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa
Publication date: 2009-12-01