Nanocomposites and nanomaterials
Conductivity of Carbon Nanomaterials Modified with Metals
Ovsiienko I.V., Tsaregradskaya T.L., Vovchenko L.L., 
Matzui L.Yu., Saenko G.V., Marinin O.D.1
Taras Shevchenko National University of Kyiv, Department of Physics
01601, Volodymyrska st. 64/13, Kyiv, Ukraine
E-mail: tsar_grd@ukr.net

The work presents the results of complex investigations of electrical conductivity of nanocarbon materials modified with metals. The investigations have been carried out on a number of nanocarbon materials such as thermoexfoliated graphite (TEG), dispersed TEG, nanographite and multiwall  carbon nanotubes (MWCNTs). Modification of nanocarbon materials have been made with liquid-phase chemical method based on the impregnation of nanocarbon by water-salt solution with the subsequent reduction of metal in a hydrogen flow. The metals used for the modification are nickel, cobalt, iron, copper and mixture of nickel and iron. The bulk specimens of modified nanocarbons were prepared by cold compacting without binder for modified TEG and with 25 % mass polyvinyl acetate for other modified nanocarbon.
 In the work in detail the dependences of the conductivity of the modified nanocarbon bulk specimens on the type and concentration of the modifying metal, the porosity and the density of the bulk specimens are analyzed. 

Fig. Dependence of resistivity а on the porosity dV/V0 of bulk specimens for TEG (1) and modified TEG with Fe (2),  Co (3),  Cu (4)  and  Ni (5), 
T= 293K	Figure presents the dependences of resistivity а on the porosity dV/V0 of the bulk specimens of modified TEG. 
It is revealed that for modified with different metals TEG there is a boundary porosity, at which there is a sharp increase of electrical resistance in the direction perpendicular to the axis of pressing. 
The factors that cause one or another kind of temperature dependence of resistance for modified nanocarbon are also analyzed in the paper.