Dispersible, metal oxide-coated, barium titanate materials

• US 6,268,054 B1
• Filed: 09/04/1997
• Issued: 07/31/2001
• Est. Priority Date: 02/18/1997
• Status: Expired due to Fees

• Current Assignee: Cabot Corporation
• Original Assignee: Cabot Corporation
• Inventors: Costantino, Stephen A., Venigalla, Sridhar, Hard, Robert A.
• Primary Examiner(s): Le, Hoa T.
• Application Number:
  US08/923,680
• Time in Patent Office: 1,426 Days
• Field of Search: 501/137, 501/138, 501/139, 428/403, 428/404
• US Class Current: 428/403
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01P 2002/34 perovskite-type (ABO3)
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/22 Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3275 Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
• CPC Class Codes: C04B 2235/3298 Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate
• CPC Class Codes: C04B 2235/449 Organic acids, e.g. EDTA, citrate, acetate, oxalate
• CPC Class Codes: C04B 2235/528 Spheres
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/5472 Bimodal, multi-modal or multi-fraction
• CPC Class Codes: C04B 2235/5481 Monomodal
• CPC Class Codes: C04B 2235/549 the particle size being expressed by crystallite size or primary particle size
• CPC Class Codes: C04B 2235/6027 Slip casting
• CPC Class Codes: C04B 2235/77 : Density
• CPC Class Codes: C04B 2235/785 : Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 35/468 : based on barium titanates
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/6263 : characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: C04B 35/62635 : Mixing details
• CPC Class Codes: C04B 35/628 : Coating the powders or the macroscopic reinforcing agents
• CPC Class Codes: C04B 35/62805 : Oxide ceramics
• CPC Class Codes: C04B 35/62807 : Silica or silicates
• CPC Class Codes: C04B 35/6281 : Alkaline earth metal oxides
• CPC Class Codes: C04B 35/62815 : Rare earth metal oxides
• CPC Class Codes: C04B 35/62818 : Refractory metal oxides
• CPC Class Codes: C04B 35/62823 : Zirconium or hafnium oxide
• CPC Class Codes: C04B 35/62826 : Iron group metal oxides
• CPC Class Codes: C04B 35/62894 : with more than one coating layer
• CPC Class Codes: C04B 35/63424 : Polyacrylates; Polymethacrylates
• CPC Class Codes: C09C 3/063 : Coating
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates
• CPC Class Codes: Y10T 428/2991 : Coated
• CPC Class Codes: Y10T 428/2993 : Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

Barium titanate-based particles having a coating comprising an oxide, hydrous oxide, hydroxide or organic acid salt of a metal other than barium or titanium, wherein at least 90 percent of said particles have a particle size less than 0.9 micrometer when said particles are dispersed by high shear mixing, useful in the fabrication of thin, fine-grained dielectric layers for multilayer ceramic capacitors with high breakdown voltage.

Claims

1. A dispersion of barium titanate-based particles, the barium titanate-based particles having a coating comprising a metal oxide, metal hydrous oxide, metal hydroxide or organic acid salt of a metal other than barium or titanium, wherein the dispersion includes greater than 30 percent by weight of said coated particles and at least 90 percent of said dispersed coated particles have a particle size less than 0.9 micrometer.

2. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a primary particle size less than 0.6 micrometer.

3. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a primary particle size less than 0.5 micrometer.

4. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a primary particle size less than 0.4 micrometer.

5. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a primary particle size less than 0.3 micrometer.

6. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a primary particle size less than 0.2 micrometer.

7. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 4.

8. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 3.

9. The dispersion of barium titanate-based particles according to claim 1 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 2.5.

10. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.8 micrometer when said particles are dispersed by high shear mixing.

11. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.7 micrometer when said particles are dispersed by high shear mixing.

12. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.6 micrometer when said particles are dispersed by high shear mixing.

13. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.5 micrometer when said particles are dispersed by high shear mixing.

14. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.4 micrometer when said particles are dispersed by high shear mixing.

15. The dispersion of barium titanate-based particles according to claim 1 wherein at least 90 percent of said coated particles have a particle size less than 0.3 micrometer when said particles are dispersed by high shear mixing.

16. The dispersion of barium titanate-based particles according to claim 1 wherein substantially all of said dispersed coated particles are equiaxed or spherical.

17. The dispersion of barium-titanate based particles according to claim 1 comprising at least 50 weight percent of said dispersed coated particles.

18. The dispersion of barium titanate-based particles according to claim 17 further comprising between 3 and 20 weight percent of a binder composition comprising a dissolved or suspended, film-forming, polymer.

19. A wet cake comprising the dispersion of barium titanate-based particles according to claim 1 including between 15 and 35 weight percent of an aqueous liquid.

20. The wet cake of claim 19 further comprising a moisture barrier that provides shelf life such that after 30 days said wet cake is dispersible by the admixture of a dispersing agent by high shear mixing into an aqueous dispersion of the coated particles, 90 percent of which have a particle size less than 1 micrometer.

21. The dispersion of claim 1, wherein the coating includes more than one chemically distinct layer, each layer comprising a metal oxide, metal hydrous oxide, metal hydroxide or organic acid salt of a metal other than barium or titanium.

22. The dispersion of claim 1, wherein said dispersed coated particles are non-milled.

23. The dispersion of claim 1, wherein the coating covers a major portion of the surface of said dispersed coated particles.

24. The dispersion of claim 1, wherein the dispersion includes greater than 40 percent by weight of said dispersed coated particles.

25. A dispersion of barium titanate-based particles, the barium titanate-based particles having a primary particle size less than 0.6 micrometer and a coating comprising an oxide, hydrous oxide, hydroxide or organic acid salt of at least one metal selected from the group consisting of lithium, magnesium, calcium, strontium, scandium, zirconium, hafnium, vanadium, niobium, tantalum, manganese, cobalt, nickel, zinc, boron, silicon, antimony, tin, yttrium, lanthanum, lead, bismuth and a Lanthanide element, wherein the dispersion includes greater than 30 percent by weight of said coated particles and at least 90 percent of said dispersed coated particles have a particle size less than 0.9 micrometer.

26. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a primary particle size less than 0.5 micrometer.

27. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a primary particle size less than 0.4 micrometer.

28. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a primary particle size less than 0.3 micrometer.

29. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a primary particle size less than 0.2 micrometer.

30. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 4.

31. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 3.

32. The dispersion of barium titanate-based particles according to claim 25 wherein said dispersed coated particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 2.5.

33. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.8 micrometer when said particles are dispersed by high shear mixing.

34. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.7 micrometer when said particles are dispersed by high shear mixing.

35. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.6 micrometer when said particles are dispersed by high shear mixing.

36. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.5 micrometer when said particles are dispersed by high shear mixing.

37. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.4 micrometer when said particles are dispersed by high shear mixing.

38. The dispersion of barium titanate-based particles according to claim 25 wherein at least 90 percent of said coated particles have a particle size less than 0.3 micrometer when said particles are dispersed by high shear mixing.

39. The dispersion of barium titanate-based particles according to claim 25 wherein substantially all of said dispersed coated particles are equiaxed or spherical.

40. The dispersion of barium titanate-based particles according to claim 25, comprising at least 50 weight percent of said dispersed coated particles.

41. The dispersion of barium titanate-based particles according to claim 40 further comprising between 3 and 20 weight percent of a binder composition comprising a dissolved or suspended, film-forming, polymer.

42. A wet cake comprising the dispersion of barium-titanate based particles according to claim 25 including between 15 and 35 weight percent of an aqueous liquid.

43. The wet cake of claim 42 further comprising a moisture barrier that provides shelf life such that after 30 days said wet cake is dispersible by the admixture of a dispersing agent by high shear mixing into an aqueous dispersion of the coated particles, 90 percent of which have a particle size less than 1 micrometer.

44. The dispersion of claim 25, wherein the dispersion includes greater than 60 percent by weight of said dispersed coated particles.

45. The dispersion of claim 25, wherein the coating includes more than one chemically distinct layer, each layer comprising a metal oxide, metal hydrous oxide, metal hydroxide or organic acid salt of a metal other than barium or titanium.

46. The dispersion of claim 25, wherein said dispersed coated particles are non-milled.

47. The dispersion of claim 25, wherein the coating covers a major portion of the surface of said dispersed coated particles.

48. The dispersion of claim 25, wherein the dispersion includes greater than 40 percent by weight of said dispersed coated particles.

49. A dispersion of non-milled barium titanate-based particles, the non-milled barium titanate-based particles having a coating comprising a metal oxide, metal hydrous oxide, metal hydroxide or organic acid salt of a metal other than barium or titanium, wherein the dispersion includes greater than 30 percent by weight of said coated particles and at least 90 percent of said dispersed coated non-milled particles have a particle size less than 0.9 micrometer when said coated non-milled barium titanate-based particles are dispersed by high shear mixing.

50. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated particles have a primary particle size less than 0.6 micrometer.

51. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated particles have a primary particle size less than 0.5 micrometer.

52. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated particles have a primary particle size less than 0.4 micrometer.

53. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated particles have a primary particle size less than 0.3 micrometer.

54. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated particles have a primary particle size less than 0.2 micrometer.

55. The non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated non-milled particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 4.

56. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated non-milled particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 3.

57. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein said dispersed coated non-milled particles have a particle size distribution decile ratio of D₉₀/D₁₀ less than 2.5.

58. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.8 micrometer when said particles are dispersed by high shear mixing.

59. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.7 micrometer when said particles are dispersed by high shear mixing.

60. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.6 micrometer when said particles are dispersed by high shear mixing.

61. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.5 micrometer when said particles are dispersed by high shear mixing.

62. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.4 micrometer when said particles are dispersed by high shear mixing.

63. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein at least 90 percent of said coated non-milled particles have a particle size less than 0.3 micrometer when said particles are dispersed by high shear mixing.

64. The dispersion of non-milled barium titanate-based particles according to claim 49 wherein substantially all of said non-milled particles are equiaxed or spherical.

65. The dispersion of non-milled barium titanate-based particles according to claim 49 comprising at least 50 weight percent of said coated non-milled particles.

66. The dispersion according to claim 65 further comprising between 3 and 20 weight percent of a binder composition comprising a dissolved or suspended, film-forming, polymer.

67. A wet cake comprising the dispersion of coated non-milled barium titanate-based particles according to claim 49 including between 15 and 35 weight percent of an aqueous liquid.

68. The wet cake of claim 67 further comprising a moisture barrier that provides shelf life such that after 30 days said wet cake is dispersible by the admixture of a dispersing agent by high shear mixing into an aqueous dispersion of the coated non-milled particles, 90 percent of which have a particle size less than 1 micrometer.

69. The dispersion of claim 49, wherein the dispersion includes greater than 60 percent by weight of said dispersed coated particles.

70. The dispersion of claim 49, wherein the coating includes more than one chemically distinct layer, each layer comprising a metal oxide, metal hydrous oxide, metal hydroxide or organic acid salt of a metal other than barium or titanium.

71. The dispersion of claim 49, wherein the coating covers a major portion of the surface of said dispersed coated particles.

72. The dispersion of claim 49, wherein the dispersion includes greater than 40 percent by weight of said dispersed coated particles.

73. The dispersion of claim 49, wherein the dispersion includes greater than 60 percent by weight of said dispersed coated particles.