title: Sonochemical approach to the synthesis of Fe(3)O(4)@SiO(2) core-shell nanoparticles with tunable properties.
abstract: In this study, we report a rapid sonochemical synthesis of monodisperse nonaggregated Fe(3)O(4)@SiO(2) magnetic nanoparticles (NPs). We found that coprecipitation of Fe(II) and Fe(III) in aqueous solutions under the effect of power ultrasound yields smaller Fe(3)O(4) NPs with a narrow size distribution (4-8 nm) compared to the silent reaction. Moreover, the coating of Fe(3)O(4) NPs with silica using an alkaline hydrolysis of tetraethyl orthosilicate in ethanol-water mixture is accelerated many-fold in the presence of a 20 kHz ultrasonic field. The thickness of the silica shell can be easily controlled in the range of several nanometers during sonication. Mossbauer spectra revealed that nonsuperparamagnetic behavior of obtained core-shell NPs is mostly related to the dipole-dipole interactions of magnetic cores and not to the particle size effect. Core-shell Fe(3)O(4)@SiO(2) NPs prepared with sonochemistry exhibit a higher magnetization value than that for NPs obtained under silent conditions owing to better control of the deposited silica quantities as well as to the high speed of sonochemical coating, which prevents the magnetite from oxidizing.
authors.affiliation: CNAB, UMR 5084, Universite Bordeaux I, II, CNRS, Le Haut Vigneau, 33170 Gradignan, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Morel
authors.forename: Sergei I
authors.initials: SI
authors.lastname: Nikitenko
authors.forename: Karine
authors.initials: K
authors.lastname: Gionnet
authors.forename: Alain
authors.initials: A
authors.lastname: Wattiaux
authors.forename: Josephine
authors.initials: J
authors.lastname: Lai-Kee-Him
authors.forename: Christine
authors.initials: C
authors.lastname: Labrugere
authors.forename: Bernard
authors.initials: B
authors.lastname: Chevalier
authors.forename: Gerard
authors.initials: G
authors.lastname: Deleris
authors.forename: Cyril
authors.initials: C
authors.lastname: Petibois
authors.forename: Alain
authors.initials: A
authors.lastname: Brisson
authors.forename: Monique
authors.initials: M
authors.lastname: Simonoff
mesh_terms: D003460:Crystallization / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry* / Q000528:radiation effects; D046911:Macromolecular Substances / Q000737:chemistry / Q000528:radiation effects; D008280:Magnetics / Q000379:methods*; D008422:Materials Testing; D008968:Molecular Conformation / Q000528:radiation effects; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry* / Q000528:radiation effects; D013010:Sonication; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D005290:Ferric Compounds; D046911:Macromolecular Substances; C000499:ferric oxide; D012822:Silicon Dioxide