  By using the five Angstrom diameter pores of calcined zeolite as the
template, we have fabricated boron doped carbon nanotube networks via the
chemical vapor deposition method. Raman data indicate the network to comprise
segments of interconnected carbon nano tubes. Transport measurements showed a
superconducting transition initiating at 40K, with a sharp downturn around 20K
to a low resistance state at 2K, accompanied by a low resistance plateau in the
current voltage characteristic, fluctuating around zero resistance. Magnetic
measurements exhibited the Meissner effect characteristic of thin
superconducting wire networks in which the superconducting wire radius is much
smaller than the London penetration length. At low magnetic field, the negative
diamagnetic susceptibility was observed to persist beyond 200K. The transport
and magnetic data are reconciled on the basis of a physical model based on weak
links comprising short, one-dimensional superconducting nano tubes, that govern
the global transport behavior.
