Synthesis and Characterization of L1₀ FePt Nanoparticles from Pt(Au, Ag)/γ‐Fe₂O₃ Core–Shell Nanoparticles

Abstract

L10 FePt nanoparticles have been prepared from Pt(Ag)/γ‐Fe2O3 and Pt(Au)/γ‐Fe2O3 core/shell nanoparticles (see Figure). Addition of Ag reduces the fcc‐to‐L10 transformation temperature by 100–150 °C, while addition of Au causes a reduction of more than 150 °C compared with pure FePt nanoparticles. Annealing at 400 °C reveals a coercivity of 2.9 kOe for the Ag and 6 kOe for the Au‐doped FePt nanoparticles.

Room‐Temperature Ferromagnetism in ZnO‐Encapsulated 1.9 nm FePt3 Nanoparticle–Composite Thin Films with Giant Interfacial Anisotropy

“…The continuing demand for increasing data storage density, i.e., ultrahigh density, has motivated widespread activities in recording media design to reduce the volume of fct‐FePt NPs while keeping high enough MCA. This has inspired scientists and engineers to explore different methods to generate fct‐FePt NPs with controllable small size and high enough MCA 2, 8–11. However, the fcc‐FePt NPs are currently reported with a critical size of about 3 nm, below which, chemical ordering drops sharply or does not even take place,12, 13 resulting in very low MCA and showing paramagnetic or superparamagnetic behavior at room temperature depending on the particle composition, therefore losing the capability for applications in ultrahigh‐density magnetic recording and high performance permanent magnets 2–5…”

Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

“…Colloidal magnetic nanoparticles, with well-defined morphology and dimensionality, are of primary importance for both fundamental studies and prospective applications in many technological areas including magnetic storage devices [ 1 , 2 ], ferrofluids [ 3 , 4 , 5 ], magnetic resonance imaging [ 6 , 7 , 8 , 9 , 10 ], drug delivery [ 11 , 12 , 13 , 14 ], bio-separation [ 15 , 16 , 17 ], hyperthermia [ 18 , 19 , 20 , 21 , 22 ], sensing [ 23 , 24 , 25 ], and catalysis [ 26 , 27 , 28 , 29 ]. Amongst them iron-based magnetic materials including iron oxides [ 30 , 31 , 32 ], metallic iron [ 33 , 34 , 35 ], and iron alloys [ 36 , 37 , 38 ] have been extensively studied for many decades.…”

Reducing the ordering temperature of FePt nanoparticles by Cu additive and alternate reduction method

“…Recently, various methods have been attempted to reduce the FePt phase transition temperature. Addition of a third nonmagnetic element, such as Ag, 19 Au, 20,21 Recently, CoPt nanoparticles were produced in aqueous medium using hydrazine as a reducing agent. 25 The coercivity of CoPt nanoparticles was 2 kOe after annealing at 500 C. In the present paper, we present the synthesis of (FePt) 85 Cu 15 nanoparticles by alternate reduction method and Cu additive.…”