Nanocomposites and nanomaterials
Conductivity characteristics of carbon nanotubes bundles irradiated with electrons.
I.I. Yaskovets, N.A. Tripachko, I.S. Rogutski, E.A. Voitsihovska, R.M. Rudenko, 
Institute of Physics NASU, Pr. Nauki 46, 03028 Kiev, Ukraine

The results of a study of the conductivity in the temperature range 4.2-330 K of bundles of single-walled carbon nanotubes irradiated by electrons with energy of 1 MeV are presented. The measurements were made after irradiation of samples at a temperature of T ≈ 7 K and subsequent annealing at a temperature of 300 K. In the fluence range  = 1014 - 1016 el / cm2, in the temperature range of 100-300 K, the conductivity G follows the temperature dependence of GT, which is characteristic of the electronic subsystem in the phase of the liquid of the Luttinger (LL). In the range of the fluences used, irradiation does not lead to the destruction of the LL phase. The exponent  depends on the number N of conducting channels in the sample and the constant coupling between the tubes in the bundle. This fact allows us to obtain important information on the number N of conducting channels in the samples under study and its dependence on the irradiation dose F. It is shown that the radiation dose dependence of the relative change of dN of the conducting channels in tube bundles has the form described in [1]: dN=A*ln(B*+1), where A and B are constants depending on the irradiation conditions. In the temperature range Т30 К the conductivity corresponds to the hopping mechanism: G(T)exp(-(T0 /T)m), where m  0.25. In the quasi one dimension anisotropic model of the carbon nanotube bundles T0  depends on the geometric mean of the localization length, lav= (lllp2)1/3 . The length of the localization in the direction perpendicular to the tube is lp  10 Å [2], and ll is the localization length of electronic states along the tube. According to the results obtained, the relative change is dll= exp(C*F). It is noteworthy that the average length of jumps is practically independent of the radiation dose.
The results obtained will be useful for comparing and analyzing the influence of irradiation on the manufacturing and modification of devices on base of carbon nanotubes. 

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2.	Maarouf A. A., Kane C. L. and Mele E. J. //Electronic structure of carbon nanotube ropes//Phys.Rev. B, 61, N16, P. 11156-11165.