Nanocomposites and nanomaterials

Magnetic and wave absorption properties of carbon-based core-shell nanostructured materials
Yakovenko O.S.1, Matzui L.Yu.1, Vovchenko L.L.1, Bodnaruk A.V.2, Kalita V.M.2,3, Bogatyrov V.M.4
1 Taras Shevchenko National University of Kyiv, Volodymyrs’ka str., 64/13, Kyiv, 01601, Ukraine.
E-mail: alenka-ya@ukr.net
2 Institute of Physics, NAS of Ukraine, Prospekt Nauky 46, Kyiv, 03028, Ukraine.
3 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Prospekt Peremohy 37, Kyiv, 03056, Ukraine.
4 Chuiko Institute of Surface Chemistry, NAS of Ukraine, General Naumov Str., 17, Kyiv, 03164, Ukraine

Ni nanosized carbon-coated particles are very promising materials for electromagnetic absorbing devices [1, 2].
The aim of this work was to investigate the effect of carbon-coated nickel and cobalt nanoparticles as filler on magnetic and wave absorption properties of epoxy composites (CMs) in 40-60 GHz frequency range. Vector panorama Agilent Technologies N5227A-200 was used for measurements of frequency dependencies of complex permittivity of CMs at room temperature. The magnetic hysteresis loops were investigated by using a vibrating sample magnetometer (LDJ-9500, LDJ Electronics, Troy, MI 48099, USA) with a maximum magnetic field of 10 kOe. The temperature hold was realized by vapor nitrogen transmission through the experimental chamber. The magnetization curves were measured at the temperature range 100-290 K.
The results demonstrate that the presence of carbon-based core-shell filler in epoxy matrices leads to an increase in the wave absorption characteristics of CMs, which are dependent on filler content and its type. The magnetic investigations were provided for pure carbon-coated nickel and cobalt powder and for the CMs. 

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