  We report the observation of Peierls-type metal-insulator transition in
carbon nanostructures formed by chemical vapor deposition inside the pore
network of the ZSM-5 zeolite. The Raman spectrum of this nanocarbon@ZSM-5
indicates a clear signature of the radial breathing mode (RBM) for (3,0) carbon
nanotubes that can constitute the carbon network segments. Electrical transport
measurements on multiple few-micron-sized nanocarbon@ZSM-5 crystals showed
metallic temperature of resistance dependence down to 30 K, at which point the
resistance exhibited a sharp upturn that is accompanied by the opening of a
quasigap at the Fermi level as indicated by the differential resistance
measurements. Further Hall measurements have yielded both the sign of the
charge carrier and its density. The latter demonstrated excellent consistency
with the quasigap data. We employed first-principles calculations to verify
that there can indeed be softening of the phonon modes in the (3,0) carbon
nanotubes.
