  Continuous Nb wires, 7-15 nm in diameter, have been fabricated by
sputter-coating single fluorinated carbon nanotubes. Transmission electron
microscopy revealed that the wires are polycrystalline, having grain sizes of
about 5 nm. The critical current of wires thicker than ~12 nm is very high
(10^7 A/cm^2) and comparable to the expected depairing current. The resistance
versus temperature curves measured down to 0.3 K are well described by the
Langer-Ambegaokar-McCumber-Halperin (LAMH) theory of thermally activated phase
slips. Quantum phase slips are suppressed.
