Achieving Isolated Fe100−xPtx Nanoparticles with High Magnetic Coercivity

• Published in: Journal of superconductivity and novel magnetism 2013, Vol.26 (12), p.3475-3485
• Main Authors: Shariatzadeh, R., Akbari, H., Zeynali, H., Arumugam, S., Kalaiselvan, G.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed Matter Physics; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Magnetic Materials; Magnetism; Materials science; Nanocrystalline materials; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity; Treatment of materials and its effects on microstructure and properties
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-013-2196-2

Monodisperse Fe 100− x Pt x ( x =37, 41, 47, 54, 61, 66, 74) nanoparticles with an average size of 4.5 nm were successfully synthesized using the chemical polyol process. As-synthesized Fe 100− x Pt x nanoparticles have the chemically disordered face-centered cubic (fcc) structure with A1 phase. To achieve an ordered structure L1 0 phase for FePt and L1 2 phase for FePt 3 particles, high-temperature annealing is required. In this work, with optimizing effective parameters of annealing and also by changing the stoichiometric of Fe 100− x Pt x nanoparticles, we were able to achieve coercivity of 16,500 Oe for Fe 53 Pt 47 , which is heat treated at 650  ∘ C for 60 min with 20  ∘ C/min (annealing heating rate). It is obvious that the annealing procedure in this temperature leads to destruction of surfactant and sintering. In this work, chemically synthesized Fe 53 Pt 47 nanoparticles were coated by a nonmagnetic CoO oxide shell to prevent them from sintering. Results show that the size of the core/shell (Fe 53 Pt 47 /CoO) nanoparticles after the annealing at a temperature of 650  ∘ C has not changed compared to the size of the as-synthesized state. Meanwhile, the coercivity of about 5580 Oe is obtained for this nanocomposite.