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Optimized Frequency Selective Surface for the Design of Magnetic Type Thin Broadband Radio Absorbers

100%

Babayan V., Kazantseva N., Kazantsev Y., Vilčáková J., Moučka R.

Acta Physica Polonica A

2017

vol. 131

issue 4

1147-1149

A novel frequency selective surface for expansion of operating frequency range of magnetic-type radio absorbers was elaborated. Frequency selective surface represents an array of flat electrically conductive elements deposited on the polyethylene terephthalate (PET) foil. The elements have a closed-loop structure on the one side of the foil, and on the opposite side, the conductive elements have the shape of solid fragments which connect projections of the neighboring closed loops. The advantage of such frequency selective surface design is that owing to capacitive shunting one can achieve the value of frequency selective surface quality factor (Q-factor) as low as 0.5. Operating frequency range and thickness of designed radio absorbers depend on the composition of polymer-magnetic material and the position of frequency selective surface therein.

Fast Microwave-Assisted Synthesis οf Uniform Magnetic Nanoparticles

100%

Kozakova Z., Bazant P., Machovsky M., Babayan V., Kuritka I.

issue 5

948-949

In recent time, magnetic nanoparticles have become widely used for preparation of advanced magnetic materials and also for biomedical applications. Requirement for preparation of particles of suitable shape and size has appeared, hence, various methods have been developed. Here we present rapid and energy saving one-pot solvothermal synthesis using microwave pressurized system. This method allows tuning the size of the particles as well as their magnetic properties. Spherical Fe_3O_4 nanoparticles are obtained in 30 min; they are uniform with average dimensions of 200 nm and exhibit ferromagnetic behavior dependent on synthesis temperature.

Size Dependent Heating Efficiency of Multicore Iron Oxide Particles in Low-Power Alternating Magnetic Fields

86%

Smolkova I., Kazantseva N., Vitkova L., Babayan V., Vilcakova J., Smolka P.

Acta Physica Polonica A

2017

vol. 131

issue 4

663-665

Aggregates of superparamagnetic nanoparticles, so called multicore particles get much attention due to collective magnetic behaviour. Despite the fact that saturation magnetization and coercivity of multicore particles are lower than for single particles of comparable size, they can generate large amount of heat in alternating magnetic field. This makes them promising for magnetic hyperthermia. However, correlation between internal magnetic structure of multicore particles and their heating ability in alternating magnetic fields are not clear yet. Detailed experimental investigations are required to determine the optimal sizes of multicore particles and the alternating magnetic field parameters to obtain maximal heat. In this study, we demonstrated how hydrodynamic size of multicore particles influences alternating magnetic field energy absorption. Dense aggregates composed of bare magnetic iron oxide nanoparticles of 13 nm were obtained by coprecipitation. Further peptization allowed to gain aqueous dispersions of multicore particles with various hydrodynamic size, varing from 85 to 170 nm, due to electrostatic stabilization. Multicore particles dispersions have saturation magnetization of 40 A m²/kg_{Fe₃O₄} and coercivity of 79.6 A/m regardless of their size. Dispersion of 85 nm multicore particles is stable and provides specific loss power of 42 W/g_{Fe}. Further increase of hydrodynamic size leads to low stability and loss of the ability to generate heat in alternating magnetic field.

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3 Acta Physica Polonica A

2 2017

1 2010

3 Babayan V.

2 Kazantseva N.

1 Bazant P.

1 Kazantsev Y.

1 Kozakova Z.

1 Kuritka I.

1 Machovsky M.

1 Moučka R.

1 Smolka P.

1 Smolkova I.

1 Vilcakova J.

1 Vilčáková J.

1 Vitkova L.

Search results

Optimized Frequency Selective Surface for the Design of Magnetic Type Thin Broadband Radio Absorbers

Fast Microwave-Assisted Synthesis οf Uniform Magnetic Nanoparticles

Size Dependent Heating Efficiency of Multicore Iron Oxide Particles in Low-Power Alternating Magnetic Fields