Carbon nanostructures and methods of preparation

Abstract

Methods and apparatus for the preparation of tubular carbon nanostructures by manipulating the heat treatment and pressure of various carbon precursors. Methods and apparatus for the preparation of tubular carbon nanostructures by bombarding graphitizable carbon precursors with the electron charged particles.

What is claimed is:  
     
         1 . A method for forming tubular carbon nanostructures which comprises heating a non-graphitizable carbon precursor in the presence of a gas at a temperature and a pressure sufficient to form the tubular carbon nanostructures from the carbon precursor, wherein the temperature and pressure are maintained such that sublimation of the non-graphitizable carbon precursor is minimized.  
     
     
         2 . The method of  claim 1 , which further comprises including a dopant in the non-graphitizable carbon precursor in an amount sufficient to form increased length tubular carbon nanostructures than if the dopant is not present.  
     
     
         3 . The method of  claim 2 , wherein the dopant is amorphous boron which is present in an amount sufficient to increase the length of the tubular carbon nanostructures to greater than 0.5 microns.  
     
     
         4 . The method of  claim 1 , wherein the non-graphitizable carbon precursor is carbon black or sucrose carbon.  
     
     
         5 . The method of  claim 1 , wherein the transformation of the precursor is conducted in the absence of any detectable quantities carbon vapor.  
     
     
         6 . The method of  claim 1 , wherein the temperature is about 1500° C. to about 3500° C.  
     
     
         7 . The method of  claim 1 , wherein the pressure is from about 50 Torr to atmospheric.  
     
     
         8 . The method of  claim 1 , wherein the temperature is about 1500° C. to about 3500° C. and the pressure is from about 50 Torr to atmospheric.  
     
     
         9 . An apparatus for forming tubular carbon nanostructures which comprises a furnace including a source of non-graphitizable carbon precursor, a gas source for adjusting pressure, a heat source sufficient for formation of tubular carbon nanostructures at a desired pressure, and a conveyor belt operably connected to the furnace, the conveyor belt for retaining the source of carbon precursor in the furnace for a period of time sufficient to form tubular carbon nanostructures.  
     
     
         10 . The apparatus of  claim 9 , wherein the temperature and pressure are maintained such that the sublimation of the non-graphitizable carbon precursor is minimized.  
     
     
         11 . The apparatus of  claim 10 , wherein the furnace is a resistance furnace.  
     
     
         12 . The apparatus of  claim 10 , wherein the source of non-graphitizable carbon supplies a dopant so that doped non-graphitizable carbon is supplied.  
     
     
         13 . The apparatus of  claim 12 , wherein the non-graphitizable carbon is doped with amorphous boron in an amount sufficient to increase the length of the tubular carbon nanostructures to greater than 0.5 microns.  
     
     
         14 . The apparatus of  claim 12 , wherein the source of non-graphitizable carbon precursor supplies carbon black or sucrose carbon.  
     
     
         15 . The apparatus of  claim 12 , wherein the heat source provides a temperature of about 1500° C. to about 3500° C.  
     
     
         16 . The apparatus of  claim 12 , wherein the pressure is maintained at from about 50 Torr to atmospheric.  
     
     
         17 . The apparatus of  claim 12 , wherein the heat source provides a temperature of about 1500° C. to about 3500° C. and the pressure is maintained at from about 50 Torr to atmospheric.  
     
     
         18 . An apparatus for forming tubular carbon nanostructures which comprises a resistance furnace including a source of non-graphitizable carbon precursor, a gas source for adjusting pressure, and a heat source sufficient for formation of tubular carbon nanostructures at a desired pressure.  
     
     
         19 . The apparatus of  claim 18 , which further comprises a conveyor belt operably connected to the resistance furnace, the conveyor belt for retaining the source of carbon precursor in the resistance furnace for a period of time sufficient to form tubular carbon nanostructures.  
     
     
         20 . The apparatus of  claim 18 , wherein the temperature and pressure are maintained such that the sublimation of the non-graphitizable carbon precursor is minimized.  
     
     
         21 . The apparatus of  claim 20 , wherein the source of non-graphitizable carbon supplies a dopant so that doped non-graphitizable carbon is supplied.  
     
     
         22 . The apparatus of  claim 21 , wherein the non-graphitizable carbon is doped with amorphous boron in an amount sufficient to increase the length of the tubular carbon nanostructures to greater than 0.5 microns.  
     
     
         23 . The apparatus of  claim 20 , wherein the source of non-graphitizable carbon precursor supplies carbon black or sucrose carbon.  
     
     
         24 . The apparatus of  claim 20 , wherein the heat source provides a temperature is about 1500° C. to about 3500° C.  
     
     
         25 . The apparatus of  claim 20 , wherein the pressure is maintained at from about 50 Torr to atmospheric.  
     
     
         26 . The apparatus of  claim 20 , wherein the heat source provides a temperature of about 1500° C. to about 3500° C. and the pressure is maintained at from about 50 Torr to atmospheric.