Water-Stable, Magnetic Silica-Cobalt/Cobalt Oxide-Silica Multishell Submicrometer Spheres

Advanced Functional MaterialsVolume 15, Issue 6 p. 1036-1040 Full Paper Water-Stable, Magnetic Silica–Cobalt/Cobalt Oxide–Silica Multishell Submicrometer Spheres† V. Salgueiriño-Maceira, V. Salgueiriño-Maceira [email protected] Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this authorM. Spasova, M. Spasova Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this authorM. Farle, M. Farle Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this author V. Salgueiriño-Maceira, V. Salgueiriño-Maceira [email protected] Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this authorM. Spasova, M. Spasova Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this authorM. Farle, M. Farle Fachbereich Physik, Experimental Physik-AG Farle, Universität Duisburg-Essen, D-47048 Duisburg, GermanySearch for more papers by this author First published: 27 May 2005 https://doi.org/10.1002/adfm.200400469Citations: 113 † The authors acknowledge financial support from the European Community (Contract No. HPRN-CT-1999-00150). The authors are indebted to Horst Zähres and Zhara Shojaaee for their assistance with TEM and SEM. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract A method to produce monodisperse magnetic composite spheres with diameters from less than 100 nm to more than 1 μm in water solution is reported. The spheres consist of a dielectric silica core and a cobalt/cobalt oxide shell which can be protected from further oxidation with an outer shell of silica or, alternatively, they can be covered with the polymer polyvinylpyrrolidone as a stabilizer. The formation of a uniform magnetic shell proceeds with the adsorption of metallic cobalt seeds, produced by the reduction of cobalt chloride with sodium borohydride, on a self-assembled layer of polyelectrolytes on the silica core. In the second step, an outer silica shell can be formed by the hydrolysis and condensation of (3-aminopropyl)trimethoxysilane and tetraethoxysilane. The double-shell composite spheres show excellent sphericity, monodispersity, and a magnetic hysteresis loop at room temperature. Citing Literature Volume15, Issue6June, 2005Pages 1036-1040 RelatedInformation