Production of nanostructures by curie point induction heating

• US 20070068933A1
• Filed: 12/14/2005
• Published: 03/29/2007
• Est. Priority Date: 05/18/2004
• Status: Active Grant

• Current Assignee: United States Secretary of Health and Human Services is the head of the United States Department of Health and Human Services, The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Original Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Inventors: Lupu, Dan, Buzatu, Dan, Darsey, Jerry, Miller, Dwight, Biris, Alexandru, Wilkes, Jon
• Granted Patent: US 7,365,289 B2
• Time in Patent Office: Days
• US Class Current: 219/633
• CPC Class Codes: B01J 12/007 in the presence of catalytically active bodies, e.g. porous plates
• CPC Class Codes: B01J 2208/00469 Radiofrequency
• CPC Class Codes: B01J 2208/00557 controlling the residence time inside the reactor vessel
• CPC Class Codes: B01J 2208/0084 inside the bed, e.g. baffles
• CPC Class Codes: B01J 23/44 Palladium
• CPC Class Codes: B01J 23/755 Nickel
• CPC Class Codes: B01J 23/88 Molybdenum
• CPC Class Codes: B01J 8/0015 Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
• CPC Class Codes: B01J 8/0285 Heating or cooling the reactor for tubular reactors in furnaces B01J8/062
• CPC Class Codes: B01J 8/087 Heating or cooling the reactor
• CPC Class Codes: B01J 8/12 moved by gravity in a downward flow
• CPC Class Codes: B01J 8/1836 Heating and cooling the reactor B01J8/42 takes precedence
• CPC Class Codes: B01J 8/1845 with particles moving upwards while fluidised
• CPC Class Codes: B01J 8/40 with fluidised bed subjected to vibrations or pulsations
• 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 32/162 characterised by catalysts
• CPC Class Codes: C23C 16/46 characterised by the method used for heating the substrate C23C16/48, C23C16/50 take precedence
• CPC Class Codes: H05B 2206/023 using the curie point of the material in which heating current is being generated to control the heating temperature
• CPC Class Codes: H05B 6/108 for heating a fluid
• CPC Class Codes: Y10S 977/844 : Growth by vaporization or dissociation of carbon source using a high-energy heat source, e.g. electric arc, laser, plasma, e-beam
• CPC Class Codes: Y10S 977/90 : having step or means utilizing mechanical or thermal property, e.g. pressure, heat
• CPC Class Codes: Y10T 117/10 : Apparatus

Abstract

An apparatus for synthesizing nanostructures. In one embodiment, the apparatus includes a heating device that defines a reaction zone therein and a susceptor made of a ferromagnetic material with a Curie temperature and placed in the reaction zone, where the Curie temperature substantially corresponds to a temperature at which the growth of desired nanostructures occurs and the heating device is capable of heating the susceptor substantially at the Curie temperature.

Claims

1. An apparatus for synthesizing nanostructures, comprising:

a. a heating device defines a reaction zone therein; and

b. a susceptor made of a ferromagnetic material having a characteristic temperature and placed in the reaction zone,

wherein the heating device is capable of heating the susceptor substantially at the characteristic temperature.

2. The apparatus of claim 1, wherein the characteristic temperature corresponds to a temperature at which the growth of desired nanostructures occurs.

3. The apparatus of claim 2, wherein the characteristic temperature is substantially equal to a Curie temperature of the ferromagnetic material.

4. The apparatus of claim 1, wherein the heating device comprises an inductively heating device.

5. The apparatus of claim 4, wherein the inductively heating device comprises an inductor coil.

6. The apparatus of claim 5, wherein the inductor coil is electrically coupled to an alternating current (AC) power supply.

7. The apparatus of claim 6, wherein the inductor coil is configured such that, in operation, it allows an alternating current to pass through to generate an electromagnetic field with a radio frequency (RF) in the reaction zone to heat the susceptor substantially at the characteristic temperature.

8. The apparatus of claim 1, wherein the susceptor comprises a foil or plate of the ferromagnetic material, and wherein the foil or plate has a surface for nanostructures to grow on the surface.

9. The apparatus of claim 8, wherein the foil or plate of the ferromagnetic material is coated with a non-magnetic conductive material.

10. The apparatus of claim 9, wherein the non-magnetic conductive material comprises gold or chromium.

11. The apparatus of claim 8, wherein the susceptor is mounted on an ultra-low heat conductivity/capacity insulator.

12. The apparatus of claim 11, wherein the ultra-low heat conductivity/capacity insulator is made of silicate.

13. The apparatus of claim 1, wherein the susceptor comprises a bed of powders made from the ferromagnetic material.

14. The apparatus of claim 13, wherein each of the powders is coated with a catalyst and support materials.

15. The apparatus of claim 1, further comprising a chamber having a first end, an opposite, second end, and a body portion defined therebetween.

16. The apparatus of claim 15, wherein the heating device is formed on the exterior surface of the body portion of the chamber such that the reaction zone is defined inside the chamber.

17. An apparatus for synthesizing nanostructures, comprising a susceptor made of a ferromagnetic material having a characteristic temperature.

18. The apparatus of claim 17, further comprising a heating device for heating the susceptor substantially at the characteristic temperature.

19. The apparatus of claim 17, wherein the characteristic temperature corresponds to a temperature at which the growth of desired nanostructures occurs.

20. The apparatus of claim 19, wherein the characteristic temperature is substantially equal to a Curie temperature of the ferromagnetic material.

21. A method for synthesizing nanostructures, comprising the steps of:

a. providing a nanostructure reactor having a reaction zone and a susceptor placed in the reaction zone, wherein the susceptor is made of a ferromagnetic material having a Curie temperature and contains a catalyst;

b. supplying a feedstock reagent to the reaction zone;

c. heating the susceptor to increase the temperature of the susceptor to the Curie temperature; and

d. keeping the susceptor substantially at the Curie temperature for a period of time for the growth of desired nanostructures from the catalyst and the feedstock reagent.

22. The method of claim 21, wherein the heating step comprises the step of inductively heating the susceptor with an electromagnetic field with a radio frequency (RF).

23. The method of claim 21, further comprising the step of optimizing the characteristic temperature for the growth of the desired nanostructures.

24. The method of claim 23, wherein the optimizing step comprises the step of selecting the ferromagnetic material with a Curie temperature that substantially corresponds to a temperature at which the growth of the desired nanostructures occurs.

25. The method of claim 21, further comprising the step of maintaining a sufficient amount of the feedstock reagent in the reaction zone.

26. The method of claim 21, wherein the susceptor comprises a foil or plate of the ferromagnetic material, and wherein the foil or plate has a surface for nanostructures to grow on the surface.

27. The method of claim 26, wherein the foil or plate of the ferromagnetic material is coated with a non-magnetic conductive material.

28. The method of claim 21, wherein the susceptor comprises a bed of powders made from the ferromagnetic material.

29. The method of claim 28, wherein each of the powders is coated with a catalyst and support materials.

30. A method for synthesizing nanostructures, comprising the steps of:

a. providing a susceptor containing a catalyst, wherein the susceptor is made of a ferromagnetic material having a characteristic temperature; and

b. heating the susceptor substantially at the characteristic temperature for the growth of desired nanostructures from the catalyst.

31. The method of claim 30, further comprising the step of supplying a feedstock reagent.

32. The method of claim 30, further comprising the step of optimizing the characteristic temperature for the growth of the desired nanostructures.

33. The method of claim 32, wherein the optimizing step comprises the step of selecting the ferromagnetic material with a Curie temperature that substantially corresponds to a temperature at which the growth of the desired nanostructures occurs.

34. The method of claim 30, wherein the heating step comprises the steps of inductively heating the susceptor to increase temperature of the susceptor to the characteristic temperature;

and keeping the susceptor substantially at the characteristic temperature for a period of time for the growth of the desired nanostructures.

35. The method of claim 34, wherein the inductively heating step is performed with an electromagnetic field with a radio frequency (RF).

36. A method for synthesizing nanostructures, comprising the steps of heating a susceptor containing a catalyst substantially at a characteristic temperature at which the growth of desired nanostructures occurs, wherein the susceptor is made of a ferromagnetic material with a Curie temperature that is substantially equal to the characteristic temperature.

37. The method of claim 36, further comprising the step of supplying a feedstock reagent to the susceptor.

38. The method of claim 36, wherein the heating step comprises the steps of inductively heating the susceptor to increase temperature of the susceptor to the characteristic temperature;

and keeping the susceptor substantially at the characteristic temperature for a period of time for the growth of the desired nanostructures.

39. The method of claim 38, wherein the inductively heating step is performed with an electromagnetic field with a radio frequency (RF).