研究目的
To further refine the polycondensation time and to study the influence of the core size and the TEOS/Fe3O4 ratio for obtaining of the Fe3O4@SiO2 core-shell nanostructures with controlled silica shell thickness.
研究成果
The study successfully synthesized Fe3O4@SiO2 core-shell nanoparticles with controlled silica shell thickness using a modified St?ber method. Key findings include the primary formation of the shell occurring within 4 hours of stirring, with growth continuing up to 8 hours. The TEOS amount and synthesis time were critical parameters affecting shell thickness. Magnetic properties of the core-shell nanoparticles were consistent with those of pure magnetite nanoparticles, considering silica dilution. These results are applicable for fabricating silica shells with controlled thickness on magnetite nanoparticles of various sizes.
研究不足
The study was limited by the synthesis conditions, including the pH drop after 6 hours due to evaporation, which ceased the hydrolysis process. Additionally, the dependence of shell thickness on TEOS concentration and core size was not linear, indicating complex kinetics.
1：Experimental Design and Method Selection:
The study used a modified St?ber method for the synthesis of silica-coated iron oxide nanoparticles, adjusting synthesis conditions to control SiO2 shell thickness.
2：Sample Selection and Data Sources:
Iron oxide nanoparticles were synthesized via precipitation with followed termostatting and precipitation with ultrasonication.
3：List of Experimental Equipment and Materials:
Materials included FeSO4 · 7H2O, FeCl2 · 4H2O, NaOH, NaNO3, TEOS, NH4OH, and isopropyl alcohol. Equipment included TEM (JEOL JEM-1011), XRD (DRON type diffractometers), FTIR spectrometer (Nicolet 380), and VSM (VSM-250 Lake Shore Cryotronics).
4：Experimental Procedures and Operational Workflow:
Iron oxide nanoparticles were synthesized, modified with sodium citrate, and then coated with SiO2 via the St?ber method. The process involved dispersion, ultrasonication, and stirring under controlled conditions.
5：Data Analysis Methods:
The nanoparticles were characterized using TEM, XRD, FTIR, and VSM to determine size, shape, phase composition, bonding, and magnetic properties.
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