http://www.cnr.it/ontology/cnr/individuo/prodotto/ID114179
High coercitivity carbon embedded L10-FePt ferromagnetic nanoparticles (Abstract/Poster in convegno)
- Type
- Label
- High coercitivity carbon embedded L10-FePt ferromagnetic nanoparticles (Abstract/Poster in convegno) (literal)
- Anno
- 2010-01-01T00:00:00+01:00 (literal)
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- Villani M.; Gaboardi M.; Calestani G.; Pernechele C.; Solzi M.; Migliori A. (literal)
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- In: ICG 2010 - Italian Crystal Growth - Progress in Functional Materials (Parma, 18-19/09 2010). (literal)
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- Stoichiometric FePt nanoparticles in the tetragonal L10 phase, (Ku = 6.6´107 erg/cm3) are one of the leading candidates for next generation high-density recording media, allowing theoretical grain stability down to 3nm [1]. As-synthesized FePt nanoparticles produced by the conventional soft chemical route (polyol process) [2,3] shows disordered face centered cubic (fcc) structure with low Ku and superparamagnetic behavior at RT. The ordered L10 tetragonal structure is usually obtained by post-annealing in a reducing environment [4,5] giving rise to particle aggregation produced by sintering that affects significantly both the final particle size and the polidispersity. A preliminary work we performed pointed out that a direct synthesis of ferromagnetic particles, based on the decomposition of Fe(acac)3 and Pt(acac)2 in reducing solvent and inert atmosphere, is made possible by the increase of the reaction temperature at 290-330°C obtained by the use of Triton X-100 as solvent and polyvinylpyrrolidone (PVP) as protective agent. The resulting nanoparticles are ferromagnetic at RT with coercitive field (Hc) ranging from 0.4 to 1.0 KOe depending on the synthesis temperature. However, as evidenced by TEM analyses, they are magnetically aggregate and, for synthesis temperatures above 300°C, embedded in an amorphous matrix produced by partial decomposition of the solvent. These observations suggested us a novel approach to the synthesis of non-aggregate ferromagnetic nanoparticles. The basic idea is to block the nanoparticles in a rigid matrix, during the synthesis, before they become ferromagnetic, to prevent magnetic aggregation. Using PEG-600 as solvent and quickly raising the temperature above 300°C cause the polyol to condense in flakes. The rapid heating, joined to the increased viscosity, limits the diffusion of the nutrient phase to the growing nuclei, resulting in monodisperse nanoparticles, with a typical size ranging around 5nm (determined by XRD and TEM), rando (literal)
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- CNR-IMEM, Parma, Dipartimento di Chimica GIAF, Parma, Italy, Dipartimento di Fisica, Università di Parma, CNR-IMM, Bologna (literal)
- Titolo
- High coercitivity carbon embedded L10-FePt ferromagnetic nanoparticles (literal)
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