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Superconductivity Taken To The Nanoth Degree
Hong Kong - July 9, 2001 Physicists at the Hong Kong University of Science and Technology have discovered that, below 15 K, single 4-Angstrom-carbon nanotubes exhibit superconductivity. This is the first time single-carbon nanotubes have been found to show superconducting properties. In recognition of this major breakthrough, Science, the world's top science journal, published the research findings on 29 June 2001. The discovery has also been reported by Chemical & Engineering News, PhysicsWeb, sina.com and People's Daily so far. Superconductivity is a property of some materials which, when cooled to temperatures within several degrees above absolute zero (-273 C, often written as O Kelvin, K), lose all their electrical resistance. However, pure carbon, an element present in all life forms, has never been found to superconduct. The HKUST physicists, led by Prof Ping Sheng, have demonstrated that when pure carbon is rolled into ultra tiny tubes, it becomes superconducting. This research represents another major breakthrough for HKUST researchers on single-walled carbon nanotubes. Last November, HKUST physicists used microporous zeolite single crystals as hosts to fabricate the world's smallest single-walled carbon nanotubes (SWNTs), which possess diameters of only 0.4 nm (nanometer). Dr Zikang Tang, assistant professor of the Physics Department, predicted then that the carbon nanotube could be an ideal one-dimensional conductor although its novel properties were yet to be explored. Based on the success of their creation, Dr Tang and his colleagues have unraveled one of the most perplexing puzzles and discovered the signature of one dimensionality in superconductivity. As the single-walled carbon nanotubes are uniform in size, regularly arrayed but isolated from each other in the zeolite matrix, they constitute an almost ideal one-dimensional (1D) system. "In a famous theorem published some 40 years ago, physicists Mermin and Wagner proved that it is impossible for abrupt superconducting transition to occur in one- or two-dimensional worlds," said Prof Ping Sheng, Head of the Physics Department and Director of HKUST's newly established Institute of Nano Science and Technology. "Our experiments and observations have confirmed the one-dimensionality effect, with extensive theoretical calculations. This will open up new horizons in basic and applied research into 1D superconductivity," said Sheng. While the research is significant in terms of its scientific breakthrough, practical applications are yet to be discovered. "It's far too early to predict anything concerning potential applications. Nevertheless, history tells us that all new material properties are eventually translated into useful applications," said Prof Sheng. "However, as the 0.4nm single-walled carbon nanotubes are at or close to their theoretical limit, they are probably the smallest wire that we can produce, and will open the door to nanocircuitries with low dissipation," he added. Prof Sheng attributed the success of the research to collaborative efforts by colleagues at HKUST's Physics Department in the past three years. "For any research to succeed, three elements are needed: novel sample fabrication; experimentation and characterization; and theory and simulation. Without any of these elements, we would not have been able to conduct the research, nor could we understand and explain the properties of the materials." "I also hope that Hong Kong people will be able to share our pride. This discovery has been made in Hong Kong by local researchers, right from its inception to its present publication. This demonstrates that Hong Kong researchers are capable of achieving major scientific breakthroughs," he said. Led by Prof Ping Sheng, the research on "Superconductivity in 4-� Single-Walled Carbon Nanotubes" was undertaken by Dr Zikang Tang, Dr Lingyun Zhang, Dr Ning Wang, Dr Xixiang Zhang, G H Wen, G D Li, Dr Jiannong Wang, and Dr Che Ting Chan. Community Email This Article Comment On This Article Related Links Hong Kong University of Science and Technology SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express Space
Satellite Launch To Boost DTH In India
Calcutta, India (SPX) Dec 28, 2005The successful launch Thursday of India's heaviest satellite from spaceport of Kourou in French Guyana may have boosted the country's space research efforts to yet another level, but it has also lifted the spirits of at least three Direct-To-Home televisions broadcasters, one of which has been waiting for years to launch its services in India. |
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