New magnesio-thermal reduction technique to produce high-purity crystalline nano-silicon via semi-batch reactor

Abstract

Abstract The production of high-purity crystalline nano-silicon from natural sources is one of the most difficult tasks due to the complexity of the process and its expense. In the present investigation, high-purity crystalline nano-silicon was produced from rice husk via a modified magnesiothermic technique. In this technique, a stainless steel semi-batch reactor was constructed to carry out the reduction process. The reduction was achieved at different reaction temperatures (i.e., 600, 700 and 800 °C) under a continuous flow of argon gas. The obtained powder was leached with HCl, HF: CH3COOH, and HF solutions. The structural properties of the obtained silicon nanoparticles (SiNPs) were analyzed and measured by X-ray fluorescence (XRF) and X-ray diffraction (XRD), while the size of the obtained particles was calculated using atomic force microscopy (AFM). The XRF results indicated that the best reduction temperature for the production of high-purity nano-silicon was 800 °C, which showed a purity of 99.923%. While at 600 °C and 700 °C the purity was 98.471 and 99.908, respectively. Also, the purity of the produced silica by the precipitation method was 99.9%. Furthermore, the results indicated that the leaching processes with HCl and HF: CH3COOH solutions played a key role in determining the quality of the final prepared nano-silicon. The prepared nano-silicon had a high-purity polycrystalline structure with a particle size of 95.4 nm. Finally, this cost-effective technique synthesized a high-purity nano-silicon with simple operation in a semi-batch reactor.