Synthesis of coiled carbon nanotubes by microwave chemical vapor deposition

Abstract

The present invention provides a coiled carbon nanotube and a method for its manufacture. The coiled carbon nanotube comprises a specific non-hexagonal/hexagonal carbon ring ratio, a specific pitch, and a specific diameter. The invention employs a microwave chemical vapor disposition system with novel processing conditions and specialized catalysts to synthesize the coiled carbon nanotubes.

Having thus described the invention, what is claimed is:  
     
         1 . A coiled carbon nanotube having a non-hexagonal/hexagonal carbon ring ratio in the range of 0.1:1 to 1:1.  
     
     
         2 . The coiled carbon nanotube of  claim 1  wherein the non-hexagonal/hexagonal carbon ring ratio is 0.1:1.  
     
     
         3 . The coiled carbon nanotube of  claim 1  wherein the non-hexagonal/hexagonal carbon ring ratio is 1:1.  
     
     
         4 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a substantially uniform distance between coils throughout its length.  
     
     
         5 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a substantially uniform diameter throughout its length.  
     
     
         6 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a substantially uniform distance between coils and diameter throughout its length  
     
     
         7 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a diameter of less than 1000 nm.  
     
     
         8 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a diameter of less than 100 nm.  
     
     
         9 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a distance between coils of less than 1000 nm.  
     
     
         10 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a distance between coils of less than 200 nm.  
     
     
         11 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a diameter of less than 1000 nm and a distance between coils of less than 1000 nm.  
     
     
         12 . The coiled carbon nanotube of  claim 1  wherein the nanotube comprises a diameter of less than 100 nm and a distance between coils of less than 200 nm.  
     
     
         13 . A coiled carbon nanotube having a substantially uniform diameter throughout its length.  
     
     
         14 . The coiled carbon nanotube of  claim 13  wherein the nanotube comprises a diameter of less than 1000 nm.  
     
     
         15 . The coiled carbon nanotube of  claim 13  wherein the nanotube comprises a diameter of less than 100 nm.  
     
     
         16 . A coiled carbon nanotube wherein the nanotube comprises a substantially uniform distance between coils throughout its length.  
     
     
         17 . The coiled carbon nanotube of  claim 16  wherein the nanotube comprises a distance between coils of less than 200 nm.  
     
     
         18 . The coiled carbon nanotube of  claim 16  wherein the nanotube comprises a distance between coils of less than 1000 nm.  
     
     
         19 . A coiled carbon nanotube having a substantially uniform diameter and a substantially uniform distance between coils throughout its length.  
     
     
         20 . The coiled carbon nanotube of  claim 19  wherein the nanotube comprises a diameter of less than 1000 nm and a distance between coils of less than 1000 nm.  
     
     
         21 . A method of manufacturing coiled carbon nanotubes, comprising: 
 placing a supported metal catalyst inside of a reaction chamber;    creating a microwave field inside said reaction chamber;    introducing a hydrocarbon source gas into said reaction chamber; and    reacting for a time and at a temperature sufficient to form said coiled carbon nanotubes.    
     
     
         22 . The method of  claim 21 , wherein an inert gas is introduced into said reaction chamber.  
     
     
         23 . The method of  claim 21 , wherein said source gas is acetylene.  
     
     
         24 . The method of  claim 21 , wherein said metal catalyst comprises a metal selected from the group consisting of iron, nickel, cobalt, and vanadium.  
     
     
         25 . The method of  claim 21 , wherein said catalyst support is selected from the group consisting of silica, zeolite, and magnesium carbonate.  
     
     
         26 . The method of  claim 21 , wherein said metal catalyst is iron and said catalyst support is magnesium carbonate.  
     
     
         27 . The method of  claim 21 , wherein said metal catalyst is iron and said catalyst support is silica.  
     
     
         28 . The method of  claim 21 , wherein said metal catalyst is nickel and said catalyst support is zeolite.  
     
     
         29 . The method of  claim 21 , further comprising the use of a stirrer to make said microwave field uniform.  
     
     
         30 . The method of  claim 21 , further comprising a stub tuner.  
     
     
         31 . The method of  claim 30 , further comprising a port circulator for controlling said stub tuner.  
     
     
         32 . The method of  claim 21 , further comprising a circulating chiller.  
     
     
         33 . A method for manufacturing coiled carbon nanotubes, comprising: 
 placing a supported metal catalyst inside of a reaction chamber;    creating a microwave field inside said reaction chamber;    introducing a hydrocarbon source gas into said reaction chamber;    using a feedback system to control the temperature inside said reaction chamber and the flow rate of said hydrocarbon source gas; and    reacting for a time and at a temperature sufficient to form said coiled carbon nanotubes.    
     
     
         34 . The method of  claim 33 , wherein an inert gas is introduced into said reaction chamber.  
     
     
         35 . The method of  claim 33 , wherein said source gas is acetylene.  
     
     
         36 . The method of  claim 33 , wherein said metal catalyst comprises a metal selected from the group consisting of iron, nickel, cobalt, and vanadium.  
     
     
         37 . The method of  claim 33 , wherein said catalyst support is selected from the group consisting of silica, zeolite, and magnesium carbonate.  
     
     
         38 . The method of  claim 33 , wherein said metal catalyst is iron and said catalyst support is magnesium carbonate.  
     
     
         39 . The method of  claim 33 , wherein said metal catalyst is iron and said catalyst support is silica.  
     
     
         40 . The method of  claim 33 , wherein said metal catalyst is nickel and said catalyst support is zeolite.  
     
     
         41 . The method of  claim 33 , further comprising the use of a stirrer to make said microwave field uniform.  
     
     
         42 . The method of  claim 33 , further comprising a stub tuner.  
     
     
         43 . The method of  claim 42 , further comprising a port circulator for controlling said stub tuner.  
     
     
         44 . The method of  claim 33 , further comprising a circulating chiller.  
     
     
         45 . The method of  claim 33 , wherein said feedback system comprises: 
 a pyrometer;    a switching power supply;    a computer;    a master flow controller; and    a mass flow controller.    
     
     
         46 . A coiled carbon nanotube produced by the process of: 
 placing a supported metal catalyst inside of a reaction chamber;    creating a microwave field inside said reaction chamber;    introducing a hydrocarbon source gas into said reaction chamber; and    reacting for a time and at a temperature sufficient to form said coiled carbon nanotubes.    
     
     
         47 . The coiled carbon nanotube of  claim 46 , wherein argon is introduced into said reaction chamber.  
     
     
         48 . The coiled carbon nanotube of  claim 46 , wherein said source gas is acetylene.  
     
     
         49 . The coiled carbon nanotube of  claim 46 , wherein said metal catalyst comprises a metal selected from the group consisting of iron, nickel, cobalt, and vanadium.  
     
     
         50 . The coiled carbon nanotube of  claim 46 , wherein said catalyst support is selected from the group consisting of silica, zeolite, and magnesium carbonate.  
     
     
         51 . The coiled carbon nanotube of  claim 46 , wherein said metal catalyst is iron and said catalyst support magnesium carbonate.  
     
     
         52 . The coiled carbon nanotube of  claim 46 , wherein said metal catalyst is iron and said catalyst support is silica.  
     
     
         53 . The coiled carbon nanotube of  claim 46 , wherein said metal catalyst is nickel and said catalyst support is zeolite.  
     
     
         54 . The coiled carbon nanotube of  claim 46 , further comprising the use of a stirrer to make said microwave field uniform.  
     
     
         55 . The coiled carbon nanotube of  claim 46 , further comprising a stub tuner.  
     
     
         56 . The coiled carbon nanotube of  claim 55 , further comprising a port circulator for controling said stub tuner.  
     
     
         57 . The coiled carbon nanotube of  claim 46 , further comprising a circulating chiller.  
     
     
         58 . The coiled carbon nanotube of  claim 46 , further comprising the use of a feedback system to control the temperature inside said reaction chamber and the flow rate of said hydrocarbon source gas.  
     
     
         59 . A coiled carbon nanotube produced by the process of  claim 58 , wherein said feedback system comprises: 
 a pyrometer;    a switching power supply;    a computer;    a master flow controller; and    a mass flow controller.    
     
     
         60 . An article of manufacture produced by the process of: 
 placing a supported metal catalyst inside of a reaction chamber;    creating a microwave field inside said reaction chamber;    introducing a hydrocarbon source gas into said reaction chamber; and    reacting for a time and at a temperature sufficient to form said coiled carbon nanotubes.    
     
     
         61 . The article of manufacture of  claim 60 , wherein argon is introduced into said reaction chamber.  
     
     
         62 . The article of manufacture of  claim 60 , wherein said source gas is acetylene.  
     
     
         63 . The article of manufacture of  claim 60 , wherein said metal catalyst comprises a metal selected from the group consisting of iron, nickel, cobalt, and vanadium.  
     
     
         64 . The article of manufacture of  claim 60 , wherein said catalyst support is selected from the group consisting of silica, zeolite, and magnesium carbonate.  
     
     
         65 . The article of manufacture of  claim 60 , wherein said metal catalyst is iron and said catalyst support is magnesium carbonate.  
     
     
         66 . The article of manufacture of  claim 60 , wherein said metal catalyst is iron and said catalyst support is silica.  
     
     
         67 . The article of manufacture of  claim 60 , wherein said metal catalyst is nickel and said catalyst support is zeolite.  
     
     
         68 . The article of manufacture of  claim 60 , further comprising the use of a stirrer to make said microwave field uniform.  
     
     
         69 . The article of manufacture of  claim 60 , further comprising a stub tuner.  
     
     
         70 . The article of manufacture of  claim 69 , further comprising a port circulator for controlling said stub tuner.  
     
     
         71 . The article of manufacture of  claim 60 , further comprising a circulating chiller.  
     
     
         72 . The article of manufacture of  claim 60 , further comprising the use of a feedback system for controling the temperature inside said reaction chamber and the flow rate of said hydrocarbon source gas.  
     
     
         73 . The article of manufacture of  claim 72 , wherein said feedback system comprises: 
 a pyrometer;    a switching power supply;    a computer;    a master flow controller; and    a mass flow controller.