Synthesis of spherical submicron-sized magnetite/silica nanocomposite particles

• Published in: Journal of sol-gel science and technology 2008-01, Vol.45 (1), p.35-41
• Main Authors: Kobayashi, Y., Saeki, S., Yoshida, M., Nagao, D., Konno, M.
• Format: Article
• Language: English
• Subjects: Ammonia; Ceramics; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Ethanol; Exact sciences and technology; Field study; General and physical chemistry; Glass; Inorganic Chemistry; Magnetic saturation; Magnetite; Materials Science; Nanocomposites; Nanoparticles; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Particulate composites; Quarks; Silicon dioxide
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-007-1648-1

This paper describes a method for fabricating spherical submicron-sized silica particles that contained magnetite nanoparticles (magnetite/silica composite particles). The magnetite nanoparticles with a size of ca . 10 nm were prepared according to the Massart method, and were surface-modified with carboxyethylsilanetriol. The fabrication of magnetite/silica composite particles was performed in water/ethanol solution of tetraethoxyorthosilicate with ammonia catalyst in the presence of the surface-modified magnetite nanoparticles. The magnetite/silica composite particles with a size of ca. 100 nm were successfully prepared at 0.05 M TEOS, 15 M water, and 0.8 M ammonia with injection of the magnetite nanoparticle colloid at 2 min after the initiation of hydrolysis reaction of TEOS. Magnetite concentration in the composite particles could be raised to 17.3 wt.% by adjustment of the injected amount of the magnetite colloid, which brought about the saturation magnetization of 7.5 emu/g for the magnetite/silica composite particles.