In this paper, silicon nanoparticles (Si-NPs) were prepared using silica (SiO2) mineral stone as raw material using magnesium-thermic chemical reduction method. The synthesis process involves extraction of silica (SiO2) powder from the raw material and then Si-NPs was prepared by chemical reduction of silica (SiO2) powder using the magnesium-thermic process. Two processes were done for synthesis: (a) magnesium-thermic reaction and annealing at T = 500 °C, 600 °C and 700 °C at N2 gas and (b) acid washing via HCl and HF. The stoichiometric ratio of Mg/SiO2 = 1:1, 1.5:1, 2:1 and 2.5:1 was also investigated in the chemical reduction conditions. To study the structure and morphology of nanoparticles, X-ray Diffraction (XRD) and Field Emission-Scanning Electron Microscope (FE-SEM) were used. Grown nanoparticles have a polycrystalline structure with spherical form with crystalline size of 20–40 nm. To study the optical band gap of Si-NPs and type of direct or indirect semiconductor, energy gap and absorption behavior of nanoparticles was investigated using the UV–Vis spectroscopy. The indirect band gap and blue shift comparison to bulk was observed at 3.62 eV, 3.47 eV and 3.43 eV for the samples synthesized in the temperatures of T = 500 °C, T = 600 °C and T = 700 °C, respectively. Also, the direct band gap was determined for nanopowders.

中文翻译：

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通过使用 SiO2 前驱体的镁热化学还原工艺，Mg/SiO2 化学计量比和退火对硅纳米粒子物理性能的影响

本文以二氧化硅（SiO2）矿物石为原料，采用镁热化学还原法制备了硅纳米颗粒（Si-NPs）。合成过程包括从原材料中提取二氧化硅 (SiO2) 粉末，然后使用镁热工艺通过化学还原二氧化硅 (SiO2) 粉末制备 Si-NP。进行了两个合成过程：（a）镁热反应和在 T = 500 °C、600 °C 和 700 °C 下在 N2 气体下进行退火和（b）通过 HCl 和 HF 进行酸洗。在化学还原条件下还研究了 Mg/SiO2 = 1:1、1.5:1、2:1 和 2.5:1 的化学计量比。为了研究纳米颗粒的结构和形态，使用了 X 射线衍射 (XRD) 和场发射扫描电子显微镜 (FE-SEM)。生长的纳米粒子具有多晶结构，呈球形​​，晶体尺寸为 20-40 nm。为了研究 Si-NPs 的光学带隙和直接或间接半导体的类型，使用 UV-Vis 光谱研究了纳米粒子的能隙和吸收行为。对于在 T = 500 °C、T = 600 °C 和 T = 700 °C 的温度下合成的样品，观察到与体相的间接带隙和蓝移比较分别为 3.62 eV、3.47 eV 和 3.43 eV。此外，还确定了纳米粉末的直接带隙。对于在 T = 500 °C、T = 600 °C 和 T = 700 °C 的温度下合成的样品，观察到与体相的间接带隙和蓝移比较分别为 3.62 eV、3.47 eV 和 3.43 eV。此外，还确定了纳米粉末的直接带隙。对于在 T = 500 °C、T = 600 °C 和 T = 700 °C 的温度下合成的样品，观察到与体相的间接带隙和蓝移比较分别为 3.62 eV、3.47 eV 和 3.43 eV。此外，还确定了纳米粉末的直接带隙。