Insights into the phase evolution-composition-structural aspect of silicon carbide powders preparing from nature silica sands of south Libya

Abstract

The silicon carbide (SiC) powders were prepared from four types of silica sands taken as a silica source. These sand samples were collected from Alhasawneh Mountain, Murzuq city, Sebha city and Zalaf region located in the southern of Libya. Here, the carbon source was citrus sinensis tree branches and the sol-gel method was used for preparing the samples. The calcination process was performed by immersing SiC samples in a bath containing silica/carbon mixture (∼600 °C) for 6 h. The X-ray diffraction (XRD) results confirmed the formation of three polytypes of 6H, 3C and 21R–SiC. The cell parameter values of SiC samples were very close to the actual value. Excluding in the 21R phase, a slight increasing in the cell parameter c value of 53.08, 53.49, 53.82, 53.30 Å was observed for SiCAlhasawneh Mountain, SiCMurzuq sand, SiCSebha Sand and SiCZalaf sand samples, respectively. The particle morphology was measured using a field emission scanning electron microscopy (FE- SEM). The SiCAlhasawneh Mountain sample showed larger particles sizes with irregular shapes. The irregular particle with large holes (from 0.5 to few microns) was observed in the SiCMurzuq sand sample. The SiCSebha Sand sample contains a few hexagonal flakes ∼179 nm in diameter. The SiCZalaf sand sample showed irregular particles with an average size of 138 nm. Raman spectra of all samples showed D and G bands at 1360 cm−1 and 1600 cm−1, respectively. The weak peak at 798 cm−1 corresponded to the transverse optical (TO) mode that appeared in SiCZalaf sand sample. The results showed that it is possible to use natural silica sands and silica/carbon bath method for synthesis of SiC product with low cost and inexpensive materials to be used in many applications of industrials.