1D-3D crossover in hopping conduction of carbynes

D.C. and A.C. conductivities of carbyne samples were studied over the temperature range 1.8-300 K at frequencies 10 MHz-1 GHz. It was established that a variation in the fraction of sp(2) bonds in carbynes induces transition from one- to two- and then to three-dimensional conduction. In the one-dimensional hopping conduction regime, the resistivity of carbynes depends on temperature as rho = rho (0) exp[(T-0/T)(1/2)], whereas Coulomb correlations are insignificant. The Hunt model of one-dimensional A.C. conductivity is experimentally confirmed. (C) 2000 MAIK "Nauka/Interperiodica".