Journal of Materials Research

Articles

Synthesis and Characterization of FeCoNiAl Nanocapsules by Plasma arc Discharge Process

Dian-Yu Genga1 c1, Woo-Young Parka2, Jin-Chun Kima2, Ji-Hun Yua2, Chul-Jin Choia2 and Zhi-Dong Zhanga3

a1 Korea Institute of Machinery and Materials, Changwon, Kyungnam 641-010, South Korea; and Shenyang National Laboratory for Materials Science, Institute of Metal Research, and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China

a2 Korea Institute of Machinery and Materials, Changwon, Kyungnam 641-010, South Korea

a3 Shenyang National Laboratory for Materials Science, Institute of Metal Research,and International Centre for Materials Physics, Chinese Academy of Sciences,Shenyang 110016, People’s Republic of China

Abstract

A series of magnetic FeCoNiAl nanocapsules was synthesized by the plasma arc discharge method; the targets of Fe, Co, Ni, and Al powders were changed with varying compositions. The compositions of the nanocapsules were found to be quite different from those of the corresponding targets; the relative amount of Al (or Ni, Co) to Fe was increased (or decreased). Structures, particles sizes, composition, surface composition, magnetic properties, and thermal stability of the nanocapsules were investigated. The saturation magnetization Ms = 106.8 emu/g and coercive force iHc = 367 Oe were achieved for the nanocapsules with the Fe62.5Co21Ni13Al2.5 target. In the FeCoNiAl nanocapsules, the binding energies of Fe, Co, and Ni were different from those of the metals Fe, Co, and Ni. The binding energies of Fe2p3/2 and Fe2p1/2 of the nanocapsules were 708.2 and 721.3 eV, respectively. The four-layer structure was proposed to give a clear statement of how the composition and phase varied radially in the nanocapsules. The major contents of the four layers—i.e., the outer shell, the inner shell, the outer core and the inner core—were amorphous alumina, crystalline alumina, transition metal oxides, and transition metal alloy, respectively. The compositions, structures, particle size, and grain size of the nanocapsules all affect their magnetic properties. In the FeCoNiAl nanocapsules, the greater th amount of the body-centered-cubic phase, the stronger the ferromagnetic magnetic properties.

(Received October 01 2004)

(Accepted June 07 2005)

Key Words:

  • Nanoparticle;
  • Magnetic properties;
  • X-ray photoelectron spectroscopy (XPS)

Correspondence:

c1 Address all correspondence to this author. e-mail: dygeng@imr.ac.cn

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