Synthesis and Characterization of Bimagnetic Bricklike Nanoparticles

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• 作者：Girija S. Chaubey ; Vikas Nandwana ; Narayan Poudyal ; Chuan-bing Rong ; J. Ping Liu
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：January 22, 2008
• 年：2008
• 卷：20
• 期：2
• 页码：475 - 478
• 全文大小：864K
• 年卷期：v.20,no.2(January 22, 2008)
• ISSN：1520-5002

文摘

Bimagnetic FePt/CoFe₂O₄ nanoparticles having a bricklike morphology were synthesized by growing a soft magnetic CoFe₂O₄ phase on FePt cubic nanoparticle seeds. The size of the soft phase could be controlled by tuning the material ratio of the FePt seeds to the CoFe₂O₄ component. To obtain magnetic hardening, the as-synthesized bricklike nanoparticles were annealed at elevated temperatures under a reductive atmosphere to convert the disordered face-centered cubic FePt phase into the ordered L1₀ phase having high magnetic anisotropy. When the particles were annealed, a gradual change was observed in morphology from bricklike particles to spherical polycrystalline nanocomposite particles because of diffusion. Meanwhile, the magnetic energy density was enhanced as a result of the exchange coupling between the hard and soft phases. The enhancement was dependent on the ratio of the volumes of the soft phase and the hard phase.