Clara Pereira - Superparamagnetic MFe2O4 (M = Fe, Co, Mn) nanoparticles: tuning the particle size and magnetic properties through a novel one-step coprecipitation route

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      Superparamagnetic   MFe2O4 (M = Fe, Co, Mn) nanoparticles:   tuning the particle size and magnetic properties through a novel   one-step coprecipitation route”, Clara Pereira, André M.   Pereira, Carlos Fernandes, Mariana Rocha, Ricardo Mendes, Maria   Paz Fernández-García, Alexandra Guedes, Pedro B. Tavares,   Jean-Marc Greneche, João P. Araújo, Cristina Freire,   Chemistry of Materials 2012,   24, 1496–1504. DOI: 10.1021/cm300301c


      Superparamagnetic ferrite nanoparticles   (MFe2O4, where M = Fe, Co, Mn) were   synthesized through a novel one-step aqueous coprecipitation   method based on the use of a new type of alkaline agent: the   alkanolamines isopropanolamine and diisopropanolamine. The role   played by the bases on the particles’ size, chemical composition,   and magnetic properties was investigated and compared directly   with the effect of the traditional inorganic base NaOH. The novel   MFe2O4 nanomaterials exhibited high   colloidal stability, particle sizes in the range of 4–12 nm, and   superparamagnetic properties. More remarkably, they presented   smaller particle sizes (up to 6 times) and enhanced saturation   magnetization (up to 1.3 times) relative to those prepared with   NaOH. Furthermore, the nanomaterials exhibited improved magnetic   properties when compared with nanoferrites of similar size   synthesized by coprecipitation with other bases or by other   methods reported in the literature. The alkanolamines were   responsible for these achievements by acting both as alkaline   agents and as complexing agents that controlled the particle size   during the synthesis process and improved the spin rearrangement   at the surface (thinner magnetic “dead” layers). These results   open new horizons for the design of water-dispersible   MFe2O4 nanoparticles with tuned properties   through a versatile and easily scalable coprecipitation route.

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