Gold powders, methods for producing powders and devices fabricated from same
Gold powders and methods for producing gold powders. The powders preferably have a small particle size, narrow size distribution and a spherical morphology. The method includes forming the particles by a spray pyrolysis technique. The invention also includes novel devices and products formed from the gold powders.
1. A powder batch comprising coated metal particles, said metal particles comprising at least about 50 weight percent gold metal and having a weight average particle size of not greater than about 5 μm and further comprising at least a first coating substantially encapsulating an outer surface of said particles, wherein said first coating has a thickness of not greater than about 50 nanometers, and wherein said metal particles have a density of at least about 15.9 g/cm 3 .
2. A powder batch as recited in claim 1 , wherein said coated metal particles comprise crystallites having an average crystallite size that is at least about 20 percent of said average particle size.
3. A powder batch as recited in claim 1 , wherein said average particle size is not greater than about 3 μm.
4. A powder batch as recited in claim 1 , wherein said average particle size is from about 0.3 μm to about 1.5 μm.
5. A powder batch as recited in claim 1 , wherein said coated metal particles have a particle size distribution wherein at least about 90 weight percent of said particles are not larger than twice said average particle size.
6. A powder batch as recited in claim 1 , wherein said coated metal particles have a particle size distribution wherein at least about 95 weight percent of said particles are not larger than twice said average particle size.
7. A powder batch as recited in claim 1 , wherein said coated metal particles are substantially spherical.
8. A powder batch as recited in claim 1 , wherein said first coating comprises a metal oxide.
9. A powder batch as recited in claim 1 , wherein said first coating comprises a metal oxide selected from the group consisting of ZrO 2 , NiO, SiO 2 , B 2 O 5 , TiO 2 , Cu 2 O, CuO, PbO, CeO 2 , Ce 2 O 3 , V 2 O 5 and Al 2 O 3 .
10. A powder batch as recited in claim 1 , wherein said first coating comprises an organic compound.
11. A powder batch as recited in claim 1 , wherein said first coating is a particulate coating.
12. A powder batch as recited in claim 1 , wherein said first coating is a non-particulate coating.
13. A powder batch as recited in claim 1 , wherein said first coating increases the sintering temperature of said metal particles.
14. A powder batch as recited in claim 1 , wherein said first coating improves the dispersibility of said metal particles in a thick film paste.
15. A powder batch as recited in claim 1 , wherein said first coating has a thickness of at least about 5 nanometers.
16. A powder batch as recited in claim 1 , wherein said first coating is an inorganic compound.
17. A powder batch as recited in claim 1 , wherein said first coating comprises an elemental metal.
18. A powder batch as recited in claim 1 , wherein said first coating is a surfactant.
19. A powder batch as recited in claim 1 , wherein said first coating comprises an organic compound selected from the group consisting of polystyrene and polymethylmethacrylate.
20. A powder batch as recited in claim 1 , wherein said first coating is a monolayer coating.
21. A powder batch as recited in claim 1 , wherein said first coating is hydrophobic.
22. A powder batch as recited in claim 1 , wherein said first coating is hydrophilic.
23. A powder batch as recited in claim 1 , wherein said first coating comprises a metal oxide selected from the group consisting of MoO 3 , Bi 2 O 3 and SnO 2 .
24. A powder batch as recited in claim 1 , wherein said weight average particle size is at least about 0.05 μm.
25. A powder batch as recited in claim 1 , wherein said metal particles comprise not greater than 0.1 atomic percent impurities.
26. A powder batch as recited in claim 1 , wherein said metal particles are metal composite particles comprising said gold metal and a non-metallic phase.
27. A powder batch as recited in claim 26 , wherein said metal composite particles comprise between 0.1 and 50 weight percent of said non-metallic phase.
28. A powder batch as recited in claim 26 , wherein said non-metallic phase is a metal oxide.
29. A powder batch as recited in claim 26 , wherein said non-metallic phase is a metal oxide selected from the group consisting of NiO, SiO 2 , Cu 2 O, CuO, B 2 O 3 , TiO 2 , ZrO 2 , Bi 2 O 3 , SnO 2 , CeO 2 , Ce 2 O 3 , V 2 O 5 and Al 2 O 3 .
30. A powder batch as recited in claim 26 , wherein said non-metallic phase comprises at least one of a simple glass and a complex glass.
31. A powder batch as recited in claim 1 , wherein said metal particles are metal alloy particles comprising said gold metal and an alloying element.
32. A powder batch as recited in claim 31 , wherein said alloying element is platinum.
33. A powder batch as recited in claim 31 , wherein said alloying element is palladium.
34. A powder batch as recited in claim 31 , wherein said alloying element is selected from the group consisting of silver, nickel, copper, tungsten, molybdenum, and tin.
35. A powder batch as recited in claim 31 , wherein said metal alloy particles comprise between 0.1 and 40 weight percent of said alloying element.
36. A powder batch comprising coated metal particles, said metal particles comprising at least about 50 weight percent gold metal and having a weight average particle size of not greater than about 5 μm and further comprising at least a first coating substantially encapsulating an outer surface of said particles, wherein said first coating has a thickness of not greater than about 50 nanometers, and wherein said first coating comprises an organic compound.
37. A powder batch as recited in claim 36 , wherein said coated metal particles comprise crystallites having an average crystallite size that is at least about 20 percent of said average particle size.
38. A powder batch as recited in claim 36 , wherein said average particle size is not greater than about 3 μm.
39. A powder batch as recited in claim 36 , wherein said average particle size is from about 0.3 μm to about 1.5 μm.
40. A powder batch as recited in claim 36 , wherein said coated metal particles have a particle size distribution wherein at least about 90 weight percent of said particles are not larger than twice said average particle size.
41. A powder batch as recited in claim 36 , wherein said coated metal particles have a particle size distribution wherein at least about 95 weight percent of said particles are not larger than twice said average particle size.
42. A powder batch as recited in claim 36 , wherein said coated metal particles are substantially spherical.
43. A powder batch as recited in claim 36 , wherein said first coating increases the sintering temperature of said metal particles.
44. A powder batch as recited in claim 36 , wherein said first coating improves the dispersibility of said metal particles in a thick film paste.
45. A powder batch as recited in claim 36 , wherein said first coating has a thickness of at least about 5 nanometers.
46. A powder batch as recited in claim 36 , wherein said first coating is a surfactant.
47. A powder batch as recited in claim 36 , wherein said first coating comprises an organic compound selected from the group consisting of polystyrene and polymethylmethacrylate.
48. A powder batch as recited in claim 36 , wherein said first coating is a monolayer coating.
49. A powder batch as recited in claim 36 , wherein said first coating is hydrophobic.
50. A powder batch as recited in claim 36 , wherein said first coating is hydrophilic.
51. A powder batch as recited in claim 36 , wherein said weight average particle size is at least about 0.05 μm.
52. A powder batch as recited in claim 36 , wherein said metal particles comprise not greater than 0.1 atomic percent impurities.
53. A powder batch as recited in claim 36 , wherein said metal particles are metal alloy particles comprising said gold metal and an alloying element.
54. A powder batch as recited in claim 53 , wherein said alloying element is platinum.
55. A powder batch as recited in claim 53 , wherein said alloying element is palladium.
56. A powder batch as recited in claim 53 , wherein said alloying element is selected from the group consisting of silver, nickel, copper, tungsten, molybdenum, and tin.
57. A powder batch as recited in claim 53 , wherein said metal alloy particles comprise between 0.1 and 40 weight percent of said alloying element.
58. A powder batch as recited in claim 36 , wherein said metal particles are metal composite particles comprising said gold metal and a non-metallic phase.
59. A powder batch as recited in claim 58 , wherein said metal composite particles comprise between 0.1 and 50 weight percent of said non-metallic phase.
60. A powder batch as recited in claim 58 , wherein said non-metallic phase is a metal oxide.
61. A powder batch as recited in claim 58 , wherein said non-metallic phase is a metal oxide selected from the group consisting of NiO, SiO 2 , Cu 2 O, CuO, B 2 O 3 , TiO 2 , ZrO 2 , Bi 2 O 3 , SnO 2 , CeO 2 , Ce 2 O 3 , V 2 O 5 and Al 2 O 3 .
62. A powder batch as recited in claim 58 , wherein said non-metallic phase comprises at least one of a simple glass and a complex glass.