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Magnetic Properties of Fe@Pt Nanoparticles with Core/Shell Morphology

100%

Zeleňáková A., Zeleňák V., Bednarčík J., Lauda M., Kováč J.

issue 5

1002-1004

We have investigated the magnetic properties of iron nanoparticles coated by platinum shell prepared by chemical procedure. Magnetic measurements using SQUID magnetometer confirm the behaviour typical for a superparamagnetic system. From the M(H) loop at 300 K the magnetic moment of each particle m_{P} ≈ 250 μ_{B} was calculated. The magnetic relaxation study by the in-phase χ' and out-of-phase χ" ac susceptibilities in frequency range 0.1-1000 Hz suggests the existence of two magnetic layers with different magnetic spin's dynamics and strong dipolar interactions between nanoparticles. The observed magnetic behaviour is caused by the blocking process of interacting superparamagnetic particles with magnetic iron core, diamagnetic platinum shell and spin-glass like behaviour magnetic interlayer between them.

Magnetic Properties of Soft Magnetic FeSi Composite Powder Cores

86%

Lauda M., Füzer J., Füzerová J., Kollár P., Strečková M., Fáberová M.

vol. 126

issue 1

144-145

Soft magnetic composites (SMCs), which are used in electromagnetic applications, can be described as ferromagnetic powder particles surrounded by an electrical insulating film. These composite materials offer several advantages over traditional laminated steel cores such as reduction in weight and size. They have some unique properties, including three-dimensional isotropic ferromagnetic behaviour, very low eddy current loss, relatively low total core loss at medium and high frequencies, high electrical resistivity and good relative magnetic permeability. FeSi powder was used as a base ferromagnetic material for preparation of soft magnetic composites. The commercial FeSi particles of a precise spherical shape were prepared in two granulometric fractions (up to 150 μm or up to 356 μm). The phenol-formaldehyde resin modified by SiO_{2} nanoparticles was used as an electroinsulating layer. The FeSi particles covered by the synthesized resin were compacted at 800 MPa into the ring samples for magnetic measurements. The final samples were treated thermally under the curing schedule, which was suggested according to thermal degradation of the modified resin.

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2 Acta Physica Polonica A

1 2014

1 2010

2 Lauda M.

1 Bednarčík J.

1 Fáberová M.

1 Füzer J.

1 Füzerová J.

1 Kollár P.

1 Kováč J.

1 Strečková M.

1 Zeleňák V.

1 Zeleňáková A.

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Magnetic Properties of Fe@Pt Nanoparticles with Core/Shell Morphology

Magnetic Properties of Soft Magnetic FeSi Composite Powder Cores