Synthesis of porous Si–C composite powder from activated raw materials

Abstract

A porous silicon-carbon composite was synthesized using a mixture of sucrose, ammonium chloride, and silicon in a neutral gas environment at 1000 °C. Effect of raw materials activation were studied (0, ‌ 1, 2, and 4 h) on the characteristics (microstructure, morphology, phase structure, carbon structure, and electrical resistance) of prepared composite powders using SEM (Scanning Electron Microscope), XRD (X-Ray Diffraction), RAMAN spectroscopy methods, and electrical resistivity measurements. Results showed that mechanical activation promoted the decomposition reaction of raw materials during heat treatment, helped to form spherical carbon particles, reduced carbon particle size (less than 200 nm), and facilitated the formation of the porous carbon structure. Raman spectra also showed the appearance of some carbon in the milled samples before the heat treatment process. Carbon peaks were not observed in the XRD patterns of composite powders due to the nanocrystalline structure of the carbon, while Raman spectra proved the presence of nanocrystalline and amorphous carbon in the structure of the prepared powders. Moreover, mechanical activation increased the content of nanocrystalline and amorphous carbon in the composite powders. Increasing the mechanical activation time up to 4 h, reduced the electrical resistivity of Si–C composite powders to 1.44 Ω-cm.