Ultrafine FePt Nanoparticles Prepared by the Chemical Reduction Method

Abstract

Monodisperse FePt nanoparticles with particle size of about 2 nm have been prepared by 1,2-hexadecanediol reduction of iron acetylacetonate and platinum acetylacetonate in dioctyl ether. The as-synthesized particles have a chemically disordered fcc structure and can be transformed into chemically ordered fct structure after thermal processing at temperatures above 500°C. The ordered fct FePt phase has high magnetic anisotropy and thus large coercivity up to 1.8 T.

Shape control of FePt nanocrystals

“…3 Typically, when a smaller amount of surfactants is injected simultaneously after the addition of Fe͑CO͒ 5 in the ether solvent, spherical FePt nanoparticles are formed. 7,[11][12][13] It has been found from our study that not only the molar ratio of surfactants but also the sequence of addition of the surfactants and metal precursors has influence on the shape of FePt nanoparticles. For example, nanorods and nanowires were obtained when oleylamine was added before the addition of Fe͑CO͒ 5 , followed by oleic acid, at the molar ratio of oleylamine to oleic acid at 4:1͓Figs.…”

“…It is known that surfactants play a vital role in growth of nanocrystals. 3,7,9,[11][12][13][14] The anisotropic interaction between the capping agents and the different facets of Fe-Pt crystals should be the key for the formation of differently shaped nanocrystals. 3 Typically, when a smaller amount of surfactants is injected simultaneously after the addition of Fe͑CO͒ 5 in the ether solvent, spherical FePt nanoparticles are formed.…”

“…[7][8][9][10] Recent progress in chemical synthesis techniques for preparing FePt nanoparticles has shown a great deal of success in tuning particle size while maintaining a narrow size distribution. [11][12][13] Progress has also been made in controlling shape of FePt nanoparticles, including preparation of one-dimensional structures such as nanorods and nanowires. [14][15][16] We recently reported that simultaneous reduction in platinum acetylacetonate ͓Pt͑acac͒ 2 ͔ and iron pentacarbonyl ͑Fe͑CO͒ 5 ͒ in the presence of 1,2-hexadecanediol ͑HDD͒, oleylamine, and oleic acid in a high-boiling ether solvent leads to the formation of FePt nanorods and nanowires.…”

Observation of L1-like chemical ordering in a decahedral FePt nanoparticle by Cs-corrected high resolution transmission electron microscopy

“…1,30,31 The as-synthesized nanoparticles were then buried in finely ground salt matrix and annealed at temperatures above 700°C. This salt-matrix annealing technique can produce ordered L1 0 -FePt nanoparticles without aggregation.…”

Tailoring magnetocrystalline anisotropy of FePt by external strain

“…Experimentally prepared 4 nm FePt nanoparticles show large coercivity of 1.8 T and large magnetization. 6 Ability to tailor coercivity and anisotropy constant of FePt could be beneficial for various applications. The sensitivity of the anisotropy constant of FePt to the modification of lattice parameters has been observed both experimentally 7,8 and theoretically.…”