title: Sonochemical coating of magnetite nanoparticles with silica.
abstract: 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.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan. dang-f@aist.go.jp
authors.forename: Feng
authors.initials: F
authors.lastname: Dang
authors.forename: Naoya
authors.initials: N
authors.lastname: Enomoto
authors.forename: Junichi
authors.initials: J
authors.lastname: Hojo
authors.forename: Keiji
authors.initials: K
authors.lastname: Enpuku
mesh_terms: D000327:Adsorption / Q000528:radiation effects; D052203:Ferrosoferric Oxide / Q000737:chemistry* / Q000528:radiation effects*; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D010316:Particle Size; D011829:Radiation Dosage; D012822:Silicon Dioxide / Q000737:chemistry* / Q000528:radiation effects*; D013010:Sonication / Q000379:methods*
chemical_list: D012822:Silicon Dioxide; D052203:Ferrosoferric Oxide