Carbon nanotubes on a substrate

• US 6,361,861 B2
• Filed: 06/14/1999
• Issued: 03/26/2002
• Est. Priority Date: 06/14/1999
• Status: Expired due to Term

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Liu, Jun, Gao, Yufei
• Primary Examiner(s): EDWARDS, NEWTON O
• Application Number:
  US09/333,876
• Publication Number:
  US 20020004136A1
• Time in Patent Office: 1,016 Days
• Field of Search: 428/367, 423/447.3, 423/249
• US Class Current: 428/367
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2202/08 Aligned nanotubes
• CPC Class Codes: C01B 2202/34 Length
• CPC Class Codes: C01B 2202/36 Diameter
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: Y10S 427/102 Fullerene type base or coating
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/842 for carbon nanotubes or fullerenes
• CPC Class Codes: Y10S 977/843 Gas phase catalytic growth, i.e. chemical vapor deposition
• CPC Class Codes: Y10T 428/12438 Composite
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2918 including free carbon or carbide or therewith [not as steel]

Abstract

The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

Claims

1. An array of a plurality of carbon nanotubes grown from a prepared substrate, wherein said prepared substrate is a conductive substrate coated with a growth catalyst, each of said carbon nanotubes having a first end attached to said prepared substrate and a second end extending from said prepared substrate, and each of said carbon nanotubes having a closed outer wall defining a core that is hollow, wherein said core is filled more than 10% with a conductive filler formed from a reaction between said conductive substrate and said growth catalyst during the growth of said each carbon nanotube.

2. The array as recited in claim 1, wherein each of said carbon nanotubes is in physical contact with at least one nearest-neighbor carbon nanotube.

3. The array as recited in claim 1, wherein said conductive substrate is selected from the group consisting of titanium, titanium carbide, vanadium, tantalum, and combinations thereof.

4. The array as recited in claim 1, wherein said conductive filler comprises carbon and an a element selected from the group of elements consisting of titanium, vanadium, tantalum, and combinations thereof.

5. The array as recited in claim 1, wherein said growth catalyst is selected from the group consisting of iron, iron oxide and combinations thereof.

6. The array as recited in claim 1, wherein said carbon nanotubes are of uniform length such that the length of each of said carbon nanotubes varies no more than 5%.

7. The array as recited in claim 6, wherein said length ranges from 1 to 2 μ

m.

8. The array as recited in claim 1, wherein said carbon nanotubes are of uniform diameter such that the diameter of each of said carbon nanotubes varies no more than 5%.

9. The array as recited in claim 1, wherein said diameter is an outside nanotube diameter ranging from 50 to 400 nm and an inside nanotube diameter ranging from 10 to 100 nm.