Nanocomposites and nanomaterials

Electrical and shielding properties epoxy resin filled with Ni@C and Co@C core-shell nanoparticles
Vovchenko  L.L.1, Matzui  L.Yu.1, Yakovenko  O.S.1, Lozitsky  O.V.*1, Len  T.A.1, Oliynyk V.V.1, Bogatyrov V.M.2, Syvolozhskyi O.A.1

1Taras Shevchenko National University of Kyiv, Volodymyrs’ka str., 64/13, Kyiv, 01601, Ukraine.
2Chuiko Institute of Surface Chemistry, NAS of Ukraine, General Naumov Str., 17, Kyiv, 03164, Ukraine
E-mail: Olozitsky@gmail.com; vovch@univ.kiev.ua

The investigation of electrical resistivity and microwave shielding properties of epoxy-based composites (CMs) filled with 60 wt.% of metal-nanocarbon Ni@C and Co@C core-shell particles has been performed. It was found that DC electrical resistivity of CMs was decreased with increase of Me content in core-shell particles and negative temperature coefficient of resistance (TCR) was observed in the temperature range 77-293K. The real part of permittivity ’ of Me@C/epoxy varies within 15-10, imaginary part ”= 15-26, magnetic permeability ’=1.4-1.2 for Ni@C/epoxy and ”=1.8 for Co@C/epoxy in the frequency range 10-67 GHz. 
	The observed sufficient increase of EMR shielding efficiency (|SET|=32-40 dB at sample thickness 2.2 mm) in Ka- and V-band for epoxy CMs with higher Ni content in core-shell Ni@C correlates with increased DC electrical conductivity of these composites compared with other CMs. The studied Me@C/epoxy CMs showed a good EMR absorptive properties (the effective absorption index Aeff=0.999 at f=65 GHz) that can be related to the enhanced dielectric and magnetic losses in CMs.	
Figure 1. EMR shielding efficiency SET of epoxy composites filled with 60 wt.% of Me@C core-shell particles