Oxygen reduced niobium oxides

• US 6,576,099 B2
• Filed: 03/23/2001
• Issued: 06/10/2003
• Est. Priority Date: 03/23/2000
• Status: Expired due to Fees

• Current Assignee: Global Advanced Metals, USA, Inc. (Global Advanced Metals Pty Ltd.)
• Original Assignee: Cabot Corporation
• Inventors: Kimmel, Jonathon L., Kitchell, Ricky W.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US09/816,689
• Publication Number:
  US 20020114722A1
• Time in Patent Office: 809 Days
• Field of Search: 204/291, 204/280, 361/528, 361/532, 361/508, 423/592, 423/62, 423/63, 752/29, 752/55
• US Class Current: 204/291
• CPC Class Codes: C01G 1/02 Oxides
• CPC Class Codes: C01G 33/00 Compounds of niobium
• CPC Class Codes: C01G 35/00 Compounds of tantalum
• CPC Class Codes: C01P 2002/70 defined by measured X-ray, neutron or electron diffraction data
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/10 Solid density
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/14 Pore volume
• CPC Class Codes: C01P 2006/16 Pore diameter
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/404 Refractory metals
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/721 Carbon content
• CPC Class Codes: C04B 35/495 based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
• CPC Class Codes: C04B 35/638 Removal thereof
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C22C 1/1089 : by partial reduction or decomposition of a solid metal compound
• CPC Class Codes: C22C 29/12 : based on oxides
• CPC Class Codes: H01G 9/042 : characterised by the material H01G11/22 takes precedence
• CPC Class Codes: H01G 9/052 : Sintered electrodes
• CPC Class Codes: H01G 9/0525 : Powder therefor

Abstract

Methods to at least partially reduce a niobium oxide are described wherein the process includes heat treating the niobium oxide in the presence of a getter material and in an atmosphere which permits the transfer of oxygen atoms from the niobium oxide to the getter material, and for a sufficient time and at a sufficient temperature to form an oxygen reduced niobium oxide. Niobium oxides and/or suboxides are also described as well as capacitors containing anodes made from the niobium oxides and suboxides. Anodes formed from niobium oxide powders using binders and/or lubricants are described as well as methods to form the anodes.

Claims

1. The method of forming an anode comprising the steps of pressing a mixture of niobium oxide powder with at least one binder or lubricant to form the pressed anode, wherein said niobium oxide has an atomic ratio of niobium to oxygen of 1:

less than 2.5.

2. The method of claim 1, wherein said niobium oxide is NbO.

3. The method of claim 1, wherein said niobium oxide comprises NbO, NbO_0.7, NbO_1.1, or combinations thereof.

4. The method of claim 1, further comprising de-binding or de-lubing the binder or lubricant.

5. The method of claim 4, wherein said de-binding or de-lubing is accomplished by thermally decomposing said binder or lubricant.

6. The method of claim 4, wherein said de-binding or de-lubing is accomplished by repeated washings in at least one solvent capable of removing said binder or lubricant.

7. The method of claim 4, further comprising sintering the anode in a vacuum or under an inert atmosphere.

8. The method of claim 1, wherein said binder or lubricant comprises an organic binder or lubricant.

9. The method of claim 1, wherein said binder or lubricant comprises poly(propylene carbonate), alkyd resin solution, polyethylene glycol, polyvinyl alcohol, stearic acid, or combinations thereof.

10. A pressed anode comprising a niobium oxide powder and at least one binder or lubricant, wherein said niobium oxide powder has an atomic ratio of niobium to oxygen of 1:

less than 2.5.

11. The pressed anode of claim 10, wherein said niobium oxide is NbO.

12. The pressed anode of claim 10, wherein said niobium oxide comprises NbO, NbO_0.7, NbO_1.1, or combinations thereof.

13. The pressed anode of claim 10, wherein said binder or lubricant is an organic binder or lubricant.

14. The pressed anode of claim 10, wherein said binder or lubricant comprises poly(propylene carbonate), alkyd resin solution, polyethylene glycol, polyvinyl alcohol, stearic acid, or combinations thereof.

15. The pressed anode of claim 10, wherein said anode has a low carbon residue after removal of the binder or lubricant and after sintering.

16. The pressed anode of claim 15, wherein said niobium oxide is sintered at a temperature of from about 1200°

C. to about 1750°

C.

17. The pressed anode of claim 15, wherein said niobium oxide is sintered at a temperature of from about 1200°

C. to about 1450°

C.

18. The pressed anode of claim 10, wherein the atomic ratio is 1:

less than 2.0.

19. The pressed anode of claim 10, wherein the atomic ratio is 1:

less than 1.5.

20. The pressed anode of claim 10, wherein the atomic ratio is 1:

1.1.

21. The pressed anode of claim 10, wherein the atomic ratio is 1:

0.7.

22. The pressed anode of claim 10, wherein the atomic ratio is 1:

0.5.

23. The pressed anode of claim 10, wherein said niobium oxide has a porous structure.

24. The pressed anode of claim 10, wherein said niobium oxide has a porous structure having from about 0.1 to about 10 micrometer pores.

25. The pressed anode of claim 10, wherein said niobium oxide is NbO, oxygen depleted NbO, niobium metal with NbO, or combinations thereof.

26. The pressed anode of claim 10, wherein said niobium comprises nodular, flaked, angular, or combinations thereof.