Dang Feng, Enomoto Naoya, Hojo Junichi, Enpuku Keiji
National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
Ultrason Sonochem. 2010 Jan;17(1):193-9. doi: 10.1016/j.ultsonch.2009.05.013. Epub 2009 May 21.
Magnetite nanoparticles were coated with silica through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under ultrasonic irradiation. The ultrasonic irradiation was used to prevent the agglomeration of the magnetite particles and accelerate the hydrolysis and condensation of TEOS. TEM, DLS, XRF, VSM, TG and sedimentation test were used to characterize the silica-coated magnetite particles. The dispersibility of silica-coated magnetite particles in aqueous solution was improved significantly and the agglomerate particle size was decreased to 110 nm. It was found that the agglomerate particle size of silica-coated magnetite particles was mainly decided by the coating temperature and the pH value in the silica-coating process. The weight ratio of silica in silica-coated magnetite particles was mainly decided by the pH value in the silica-coating process. The dispersibility of silica-coated magnetite particles was mainly decided by the agglomerate particle size of the suspension. The oxidation of magnetite particles in air was limited through the coated silica. The magnetism of silica-coated magnetite particles decreased slightly after silica-coating.
通过在超声辐照下使正硅酸四乙酯（TEOS）水解和缩合，将磁铁矿纳米颗粒包覆二氧化硅。超声辐照用于防止磁铁矿颗粒团聚，并加速TEOS的水解和缩合。采用透射电子显微镜（TEM）、动态光散射（DLS）、X射线荧光光谱（XRF）、振动样品磁强计（VSM）、热重分析（TG）和沉降试验对包覆二氧化硅的磁铁矿颗粒进行表征。包覆二氧化硅的磁铁矿颗粒在水溶液中的分散性显著提高，团聚粒径减小至110nm。发现包覆二氧化硅的磁铁矿颗粒的团聚粒径主要由包覆温度和包覆过程中的pH值决定。包覆二氧化硅的磁铁矿颗粒中二氧化硅的重量比主要由包覆过程中的pH值决定。包覆二氧化硅的磁铁矿颗粒的分散性主要由悬浮液的团聚粒径决定。通过包覆二氧化硅，限制了磁铁矿颗粒在空气中的氧化。包覆二氧化硅后，包覆二氧化硅的磁铁矿颗粒的磁性略有下降。
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