Ultra-small single-walled carbon nanotubes (SWNTs) are successfully fabricated in the channels of zeolite AlPO4-5 (AFI) single crystals by pyrolysis of tripropylamine molecules in the channels. These nanotubes have been observed directly by transmission electron microscopy, as well as by diffuse X-ray scattering and micro-Raman measurements of the nanotube breathing mode. The data consistently indicate a nanotube diameter of as small as 0.4 nm, probably at or close to the theoretical limit. These mono-sized small nanotubes perhaps constitute the best example of one-dimensional (1-D) quantum wires. They show novel electronic properties. Investigation of the magnetic and transport properties of single-walled small diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 K, 0.4 nm tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation super-current. The measured superconducting characteristics display smooth temperature variations owing to 1-D fluctuations, with a mean field superconducting transition temperature of 15 K.
Bibliographical noteFunding Information:
We are grateful to Profs. R. Saito, N. Nagasawa and Dr. W.K. Ge for their valuable comments. This research was supported by the RGC grants HKUST 6152/99P and HKUST6149/01P.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry