Showing papers on "Nanotube published in 1992"

Large-scale synthesis of carbon nanotubes

Abstract: INTEREST in carbon fibres1,2 has been stimulated greatly by the recent discovery of hollow graphitic tubules of nanometre dimensions3. There has been much speculation about the properties and potential application of these nanotubes4–8. Theoretical studies predict that their electronic properties will depend on their diameter and degree of helicity4,5. Experimental tests of these ideas has been hampered, however, by the lack of macroscopic quantities of the material. Here we report the synthesis of graphitic nanotubes in gram quantities. We use a variant of the standard arc-discharge technique for fullerene synthesis under a helium atmosphere. Under certain conditions, a carbonaceous deposit forms on one of the graphite rods, consisting of a macroscopic (diameter of about 5 mm) cylinder in which the core comprises pure nanotubes and nanoscale particles in high yield. The purity and yield depend sensitively on the gas pressure in the reaction vessel. Preliminary measurements of the conductivity of the bulk nanotube material indicate a conductivity of about 100 S cm–11.

Production of carbon nanotube

Abstract: PURPOSE: To control the diameter and length of a nanotube and narrow the distribution thereof by accurately controlling the temperature of a reactional chamber and keeping the temperature of a plasma, i.e. the temperature of the reactional system for producing the nanotube constant. CONSTITUTION: A synthesizer is constructed from a circuit composed of a movable positive electrode 5 and a negative electrode 3 for producing an arc discharge plasma 2, a DC power source device 10 therefor, an oven 1 equipped with a heater and a cooler covering the electrode part, a temperature controller 9 for controlling the heater and cooler for the oven 1, a reactional chamber 8 for covering the whole oven, a gas discharge device 11 for carrying out the gas discharge in the interior of the chamber and a gas introduction device (rare gas cylinder) 12 for feeding a rare gas to the chamber. The temperature range of the reactional system filled with the rare gas is regulated to 1000-4000°C to perform arc discharge. Carbon is evaporated and then condensed to form a carbon nanotube 4. The temperature of the plasma part is controlled to reduce the size distribution of the nanotube and improve the aspect ratio. COPYRIGHT: (C)1994,JPO&Japio