Carbon Materials Comprising Carbon Nanotubes and Methods of Making Carbon Nanotubes

Abstract

The present invention relates to carbon materials comprising carbon nanotubes, powders comprising carbon nanotubes and methods of making carbon nanotubes. In the methods of the present invention, the size and/or formation of floating catalyst particles is closely controlled. The resulting carbon nanotubes typically exhibit armchair chirality and typically have metallic properties. The carbon nanotubes produced by this method readily form bulk materials, which typically have a conductivity of at least 0.7×10 6 Sm −1 in at least one direction. The invention has particular application to the manufacture of components such as electrical conductors. Suitable electrical conductors include wires (e.g. for electrical motors) and cables (e.g. for transmitting electrical power).

What is claimed is: 
     
         1 . A carbon fiber comprising at least 75% by weight of carbon nanotubes, wherein at least 70% by number of the carbon nanotubes have a diameter in the range from 1 nm to 2.5 nm, and wherein the carbon fiber has a conductivity of at least 0.7×10 6 Sm −1  in at least one direction. 
     
     
         2 - 3 . (canceled) 
     
     
         4 . A carbon fiber according to  claim 1  which has a length greater than 0.5 m. 
     
     
         5 . A carbon fiber according to  claim 1 , wherein the fiber has a density of at least 0.1 g cm −3 . 
     
     
         6 . A carbon fiber according to  claim 1 , wherein the fiber has a specific strength of at least 0.1 GPa SG −1  in at least one direction. 
     
     
         7 . A carbon fiber according to  claim 1 , wherein the fiber has a specific stiffness of 30 GPa SG −1  or more. 
     
     
         8 . A carbon material according to  claim 1 , having a plurality of catalyst particles dispersed in the fiber, wherein the fiber comprises 20 wt % or less of catalyst particles. 
     
     
         9 . A carbon fiber according to  claim 8  wherein at least 70% by number of the catalyst particles have a diameter in the range from 0.5 nm to 4.5 nm. 
     
     
         10 . A carbon fiber according to  claim 1 , comprising a plurality of carbon nanotubes; a plurality of catalyst particles dispersed in the fiber; and incidental impurities. 
     
     
         11 . A carbon fiber according to  claim 1 , wherein at least 50% by number of the carbon nanotubes are single-walled armchair carbon nanotubes. 
     
     
         12 . A carbon fiber according to  claim 8  wherein the catalyst particles comprise transition metal atoms. 
     
     
         13 . A carbon fiber according to  claim 8  wherein the catalyst particles comprise sulphur atoms. 
     
     
         14 . A carbon fiber according to  claim 8  wherein the catalyst particles comprise an inner core of transition metal atoms surrounded by a shell or cage of sulphur atoms. 
     
     
         15 . A carbon fiber according to  claim 1  having a diameter equal to or greater than 1 μm and equal to or less than 10 cm. 
     
     
         16 . A carbon fiber according to  claim 1  wherein a high proportion of the carbon nanotubes are metallic. 
     
     
         17 . A carbon fiber according to  claim 1  wherein a high proportion of the carbon nanotubes have armchair chirality. 
     
     
         18 . A carbon film comprising at least 75% by weight of carbon nanotubes, wherein at least 70% by number of the carbon nanotubes have a diameter in the range from 1 nm to 2.5 nm, and wherein the carbon film has a conductivity of at least 0.7×10 6 Sm −1  in at least one direction. 
     
     
         19 . A carbon material comprising at least 75% by weight of carbon nanotubes, wherein at least 70% by number of the carbon nanotubes have a diameter in the range from 1 nm to 2.5 nm, and wherein the carbon material has a conductivity of at least 0.7×10 6  Sm −1  in at least one direction, wherein a plurality of catalyst particles are dispersed in the material, wherein the material comprises 20 wt % or less of catalyst particles, wherein the catalyst particles comprise sulphur atoms.