The transitional model from carbon nanotube to diamond has been established. The transition has been accomplished from carbon nanotube to carbon onion and then to diamond through laser irradiation. The transition from tube to onion under laser irradiation experiences the process of structure collapse of the tube and re-organization of carbon clusters. Carbon atoms in onions have some sp(3) character due to the insertion of pentagons in hexagon networks and curling of the structure. So onions are easier than graphite to transform into diamond. Laser irradiation can give rise to the loss of atoms by sputtering and interstitial atoms among shells. Because of the surface tension a state of self compression is formed in carbon onions and the pressure can induce the transition from onion to diamond. (C) 1998 Elsevier Science Ltd. All rights reserved. References: 25
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