Ultra-small single-wall carbon nanotubes produced using micro-pyrolysis in the channels of AIPO4-5 single crystals
Tang Z.K.
Source PublicationDevice Research Conference - Conference Digest, DRC
AbstractWe report our experimental and theoretical studies on the ultra-small SWNTs fabricated in the 1nm channels of AFI zeolite single crystals. In 1993, Iijima's group as well as Bethune's group found that the use of transition-metal catalysts could lead to nanotubes with only a single wall. The diameter of each freestanding SWNT ranges from 0.7 nm to a few tens nanometers with a length of about 1 μm. Although theoretical calculations have predicted the stability of a SWNT with diameter as small as 0.4 nm, the existence of free-standing SWNTs with a diameter smaller than that of C fullerene (0.7 nm) has been in doubt for quite a while because of the extreme curvature and reactivity of these structures. Carbon nanotubes with diameters of as small as 0.5 nm, and 0.4 nm have been observed existing in the centre of multi-walled carbon nanotubes. It is still not clear, however, that whether these small nanotubes are stable in free space. We have shown that 0.4 nm-sized SWNTs can be produced by means of paralysing hydrocarbon molecules in 1 nm-sized channels of AlPO-5 (AFI) single crystals [1]. These small nanotubes perhaps constitute the best example of one-dimensional (1D) quantum wires. In this lecture, we report the novel properties of the ultra-small SWNTs. The SWNTs are highly aligned and uniform in size, they show interesting optical and electrical transport properties. The optical dipole selection rules are discussed, and the absorption bands are assigned to the dipole transitions between the van-Hove singularities [2]. The electronic structures of the ultra-small nanotubes were probed by means of resonant Raman scattering. Investigation of the magnetic and transport properties of these SWNTs revealed that at temperatures below 20 K, the 0.4 nm tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 K [3]. © 2005 IEEE.
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Document TypeConference paper
CollectionUniversity of Macau
AffiliationHong Kong University of Science and Technology
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Tang Z.K.. Ultra-small single-wall carbon nanotubes produced using micro-pyrolysis in the channels of AIPO4-5 single crystals[C],2005:233-234.
APA Tang Z.K..(2005).Ultra-small single-wall carbon nanotubes produced using micro-pyrolysis in the channels of AIPO4-5 single crystals.Device Research Conference - Conference Digest, DRC,2005,233-234.
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