The temperature dependence of the electrical resistivity and the negative magnetoresistance of carbon nanoparticles

Temperature dependences of the electrical resistivity of samples of carbon nanoparticles obtained from nanodiamonds by annealing at 1800, 1900, and 2140 K were studied. The magnetoresistance of these samples was measured at 4.5 K. Data on the positive magnetoresistance obtained in fields above 3 T were used to estimate the mean free path l of carriers at liquid-helium temperature, l similar to 12 Angstrom for a sample annealed at 1800 K, l similar to 80 Angstrom for a sample annealed at 1900 K, and l similar to 18 Angstrom for the case of annealing at 2140 K. The samples annealed at 1800 and 2140 K exhibit a negative magnetoresistance in fields below 2 T. The carrier concentrations n in the samples annealed at 1800 and 2140 K were estimated as n similar to 8 x 10(21) and 3 x 10(21) cm(-3), respectively. (C) 2002 MAIK "Nauka / Interperiodica".