Fabrication of ordered FePt nanoparticles with a cluster gun

Abstract

In this study we present a technique to obtain ordered fct FePt particles embedded in a C matrix. FePt nanoparticles are formed inside a high-pressure sputtering cell, called a particle gun (PG), and subsequently deposited on the substrate through a small orifice. These particles have a uniform size distribution with an average particle size that can be controlled in the range of 3–10 nm by adjusting the sputtering cell pressure, power, distance between the magnetron and the orifice, and by using a liquid nitrogen cooling jacket. The particles are converted to the L10 phase as they pass through a specially designed heating stage, attached to the top of the PG, heated by halogen lamps, thus avoiding alloying and oxidation effects. A strong dependence of coercivity on both the particle size and temperature was observed.

Direct synthesis and characterizations of fct-structured FePt nanoparticles using poly(N-vinyl-2-pyrrolidone) as a protecting agent

“…Thus, this is thought to prevent nanoparticles from sintering by the post-annealing. What is more, the study of direct chemical synthesis of ferromagnetic fct-structured FePt nanoparticles was recently carried out by using low molecular weight ligands like oleic acid and oleylamine [52][53][54]. We have succeeded in direct synthesis of FePt nanoparticles having the fct structure without post-annealing by using poly(N-vinyl-2-pyrrolidone) (PVP) polymer instead of low molecular weight ligands as a stabilizer, and in easy control of the diameter of nanoparticles by changing the molar ratio of the polymer to metallic precursors and by increasing the refluxing time and reaction temperature for synthesis.…”

Direct Synthesis of Isolated L10 FePt Nanoparticles in a Robust TiO2 Matrix via a Combined Sol–Gel/Pyrolysis Route

“…However, this usually comes at the expense of grain growth. [3] Other approaches, such as rapid annealing, [7] which has shown moderate success, or non-traditional methods for annealing based on light absorption [8] or pulsed laser heating [9] have been explored recently. Post-deposition organic coating and self-assembly of gas-phase synthesized nanoparticles, [10] as well as pre-annealing at moderate temperatures, [11] aimed at decomposing the surfactant without sintering particles, have also been suggested.…”

A Micellar Approach to Magnetic Ultrahigh‐Density Data‐Storage Media: Extending the Limits of Current Colloidal Methods

“…Furthermore, undesirable collective magnetic dynamics arise at such small interparticle distances through dipolar coupling; [24,25] collective modes, however, are clearly at odds with the idea of storing magnetic data in individual nanoparticles. Finally, the heat-treated colloidal FePt nanoparticles are found to be highly oxidized and contaminated by carbon because of the thermally induced decomposition of the organic shell.[26]Recent alternative routes for the synthesis of L1 0 FePt nanoparticles include their formation in cluster beams [11,27] and from wet-chemical procedures at elevated temperatures. [10,14] However, even in these cases, the particles still need to be encapsulated with an organic-ligand shell, either after deposition from a cluster beam [12] or during synthesis, to guarantee their ordered organization.…”