Abstract In this study, Fe–Si@SiO2 core–shell particles were synthesized by a fluidized bed chemical vapor deposition process at various gaseous C8H20O4Si precursor concentrations (2.0–5.5 vol%). The substrate temperature and deposition times for the study were 920 K and 30 min, respectively. The influence of gaseous C8H20O4Si precursor concentration on the microstructures and performances of the Fe–Si@SiO2 core–shell particles was investigated. X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to confirm the reaction mechanism of C8H20O4Si on the Fe-6.5 wt%Si substrate particles. The evolution process from the Fe-6.5 wt%Si to the Fe–Si@SiO2 core–shell structure that the greats quantity were in condensation reactions among C8H20O4Si precursor, Si(OC2H5)x(OH)4−x (x = 0–3) intermediate products and Fe-6.5 wt%Si substrate particles. The gaseous C8H20O4Si precursor concentration changes the surface morphology of the particles and increases the SiO2 deposition rate. Sub-micro scale SiO2 deposits, porous and partially covered SiO2 coatings, complete SiO2 coatings, and microscale SiO2 clusters were dominant at low, intermediate, and high concentrations of gaseous C8H20O4Si precursor. Upon increasing the gaseous C8H20O4Si precursor concentration from 2.0 to 4.0 vol%, the SiO2 deposition rate demonstrated a linear increase. A gaseous C8H20O4Si precursor concentration of 3.0 vol% was necessary to obtain a complete Fe–Si@SiO2 core–shell structure. The magnetic moment per unit weight of the complete Fe–Si@SiO2 core–shell particles were slightly lower than that of Fe-6.5 wt%Si substrate particles, while the resistivity values increased by three orders of magnitude.

中文翻译：

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使用流化床 CVD 的 Fe-6.5 wt% Si 颗粒的二氧化硅涂层：前体浓度对核壳结构的影响

摘要 在本研究中，Fe-Si@SiO2 核壳颗粒是通过流化床化学气相沉积工艺在各种气态 C8H20O4Si 前驱体浓度（2.0-5.5 vol%）下合成的。研究的基板温度和沉积时间分别为 920 K 和 30 分钟。研究了气态 C8H20O4Si 前驱体浓度对 Fe-Si@SiO2 核壳颗粒的微观结构和性能的影响。X 射线衍射、傅里叶变换红外光谱和 X 射线光电子能谱用于确认 C8H20O4Si 在 Fe-6.5 wt% Si 基材颗粒上的反应机理。从 Fe-6.5 wt% Si 到 Fe-Si@SiO2 核壳结构的演化过程，大量发生在 C8H20O4Si 前驱体之间的缩合反应中，Si(OC2H5)x(OH)4-x (x = 0–3) 中间产物和 Fe-6.5 wt% Si 基材颗粒。气态 C8H20O4Si 前体浓度改变了颗粒的表面形态并提高了 SiO2 沉积速率。亚微米级 SiO2 沉积物、多孔和部分覆盖的 SiO2 涂层、完整的 SiO2 涂层和微米级 SiO2 簇在低、中和高浓度的气态 C8H20O4Si 前体中占主导地位。在将气态 C8H2O4Si 前驱体浓度从 2.0 vol% 增加到 4.0 vol% 后，SiO2 沉积速率表现出线性增加。要获得完整的 Fe-Si@SiO2 核壳结构，需要 3.0 vol% 的气态 C8H20O4Si 前驱体浓度。完整的 Fe-Si@SiO2 核壳颗粒的单位重量磁矩略低于 Fe-6.5 wt% Si 基材颗粒，