Method for making nanotubes and nanoparticles

• US 6,063,243 A
• Filed: 11/25/1997
• Issued: 05/16/2000
• Est. Priority Date: 02/14/1995
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Zettl, Alexander Karlwalter, Cohen, Marvin Lou
• Primary Examiner(s): Mayekar, Kishor
• Application Number:
  US08/978,437
• Time in Patent Office: 903 Days
• Field of Search: 204/166, 204/173, 204/178
• US Class Current: 204/164
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 21/0648 After-treatment, e.g. grinding, purification transformation of hexagonal into cubic or wurtzitic boron nitride C04B35/5831
• CPC Class Codes: C01B 21/0828 Carbonitrides or oxycarbonitrides of metals, boron or silicon
• CPC Class Codes: C01P 2004/13 Nanotubes
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: Y10S 977/734 Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.
• CPC Class Codes: Y10S 977/842 for carbon nanotubes or fullerenes

Abstract

The present invention is an apparatus and method for producing nano-scale tubes and particles. The apparatus comprises novel electrodes for use in arc discharge techniques. The electrodes have interior conduits for delivery and withdrawal of material from the arc region where product is formed. In one embodiment, the anode is optionally made from more than one material and is termed a compound anode. The materials used in the compound anode assist in the reaction that forms product in the arc region of the apparatus. The materials assist either by providing reaction ingredients, catalyst, or affecting the reaction kinetics. Among other uses, the inventive apparatus is used to produce nanotubes and nanoparticles having a variety of electrical and mechanical properties.

Claims

1. A method for producing nano-scale particles and tubes, comprising the steps of:

a) providing an ambient gas environment in a vacuum chamber;

b) providing a first electrode and a second electrode in the chamber wherein at least one of the electrodes has an interior region comprising one or more conduits wherein each conduit connects a fluid source located outside the chamber to a coolant core inside the electrode, the coolant core having a drain through an exit conduit to the exterior of the chamber;

c) moving material through a conduit in the first electrode;

d) cooling the at least one electrode by circulating coolant through the cooling core; and

e) applying a voltage between the first electrode and the second electrode, sufficient to generate an arc in an arc region, to form the nano-scale particles or tubes from the material.

2. The method of claim 1 wherein the material moved through the conduit is moved from a reservoir outside the vacuum chamber to the arc region.

3. The method of claim 1 further comprising moving a product formed in the arc region through a conduit in the second electrode to a region outside the vacuum chamber.

4. A method for producing nano-scale particles and tubes comprising BN, BC₂ N, or BC₃, or a combination thereof, comprising the steps of:

a) providing an initial ambient nitrogen gas environment in a vacuum chamber of about 650 torr.

b) providing a compound anode;

c) cooling a cathode by circulating coolant through a cooling core of the cathode;

d) applying a voltage between about 1 and about 100 volts across the anode and the cooled cathode; and

e) collecting a product formed in an arc region between the anode and the cathode and deposited on the electrodes.

5. The method of claim 4 wherein the compound anode comprises a rod of boron nitride inserted into a hollow tungsten electrode.

6. The method of claim 4 wherein the compound anode comprises a rod of boron nitride inserted into a hollow graphite electrode.

7. The method of claim 4 wherein the arc region is maintained at less than about one millimeter.

8. The method of claim 4 wherein the applied voltage is between about 10 and about 60 volts.

9. The method of claim 8 wherein the applied voltage is between about 15 and about 35 volts.

10. The method of claim 4 wherein the voltage is applied by ramping a current between the anode and the cathode from about 30 amps d.c. to about 60 amps d.c.

11. The method of claim 4 wherein the voltage of between about 10 and about 30 V is applied to the electrodes by ramping a current between about 50 to about 140 amps.

12. A method for producing nano-scale particles and tubes, comprising essentially materials chosen from the group comprising BN, BC₂ N, or BC₃, or a combination thereof, comprising the steps of:

a) providing an ambient gas environment in a vacuum chamber;

b) providing a compound anode wherein the compound anode comprises a rod of boron nitride inserted into a hollow first electrode; and

c) applying a voltage, between the first electrode and a second electrode, sufficient to generate an arc in an arc region, to form the nano-scale particles or tubes from the boron nitride.