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Monodispersed ferromagnetic FePt nanoparticles, partially ordered in the L10 phase, were directly prepared without further annealing by high temperature synthesis (≈300 °C) involving poly(N-vinyl-2-pyrrolidone) and Triton X-100 as protective agent and reaction solvent respectively. Depending on the synthesis conditions, nanoparticles with average sizes ranging from 5 to 7 nm and coercive fields reaching 0.1 T at 300 K were obtained, but they invariably aggregate by magnetic dipolar interaction. By increasing the solvent viscosity (using PEG 600), 5 nm superparamagnetic nanoparticles are embedded in an amorphous matrix derived from solvent condensation/decomposition, thus avoiding aggregation. Nanoparticles are then completely converted to the hard tetragonal L10 phase, preserving the original size, by annealing in a vacuum at higher temperatures that, at the same time, transform the matrix into …
Royal Society of Chemistry
Publication date: 
1 Jan 2011

Massimo Solzi, Chiara Pernechele, Gianluca Calestani, Marco Villani, Mattia Gaboardi, Andrea Migliori

Biblio References: 
Volume: 21 Issue: 45 Pages: 18331-18338
Journal of Materials Chemistry