Structure Optimization of FePt Nanoparticles of Various Sizes for Magnetic Data Storage

Abstract

Surfactant-coated, fcc disordered FePt nanoparticles of three different sizes between 3 and 7 nm were prepared and washed according to a modified reaction route based on Sun et al. [1] Hexane dispersions of nanoparticles were dried on transmission electron microscopy (TEM) grids, and the resulting monolayers were annealed by a sinter-free procedure at 600°C and at 650°C for 2 hours, respectively, developing the L1 0 phase while preserving their monodispersity. The order parameter of the L1 0 phase was measured using electron diffraction from statistically large ensembles of nanoparticles using an X-ray-like signal collection technique. The order parameter increases with particle size and with the temperature in the range 600°C to 650°C, being close to unity for the 7.2-nm particles annealed at 650°C for 2 hours.

Magnetic phase transition of annealed FePt based nanoparticles synthesized by using Fe(β-diketonate)3

“…During the annealing, small particles are also incorporated into the larger particles due to the Ostwald ripening [17] resulting to the larger spacing between the annealed particles. Sinter-free FePt nanoparticles after annealing at 650 C have been reported [18]. However, monolayers of those annealed particles were obtained only in small areas in contrast to long-range monolayers of annealed particles obtained in the present work.…”

Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

“…Nanometer‐sized magnetic nanoparticles have received considerable attention because of their unique physical and chemical properties owing to their extremely small size and large specific surface area 1–3. Magnetic nanoparticles have been used in many applications such as data storage devices,4–6 and skin care products 7. In recent years, nanometer‐sized magnetic nanoparticles have been used in both medical and biological fields owing to their strong magnetic properties and virtually no toxicity for applications including drug delivery,8–11 biosensors,12, 13 water purification systems14, 15 and biomolecular separation/purification 10, 16–19…”

Experimental measurements of the heats of formation of Fe3Pt, FePt, and FePt3 using differential scanning calorimetry

“…[1][2][3][4][5][6][7][8][9][10][11] The formation of this phase is accomplished in a number of ways, including deposition from an alloy target, codeposition of the constituent elements and deposition of layered Fe and Pt structures. Depending on the choice of the deposition temperature, the L1 0 phase will either form during the deposition step or during the annealing treatment following deposition.…”