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A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising pre-selecting a desired percent-reduction in the average aggregate particle diameter of the metal oxide particles, providing a dispersion standard pertaining to

A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising pre-selecting a desired percent-reduction in the average aggregate particle diameter of the metal oxide particles, providing a dispersion standard pertaining to a dispersion of the aggregate metal oxide particles, wherein the dispersion standard correlates (i) the solids concentration of the dispersion with (ii) the percent-reduction in the aggregate particle diameter of the aggregate metal oxide particles that occurs when the dispersion is milled in a high-shear mixer, and preparing and milling a dispersion of the aggregate metal oxide particles in a high-shear milling device at a solids concentration that is within 10% of the solids concentration determined by the standard to provide a dispersion of aggregate metal oxide particles having the desired average aggregate particle diameter. Also provided is a method for reducing the average aggregate particle diameter of aggregate metal oxide particles, and a dispersion prepared by the method.

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What is claimed is: 1. A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising (a) providing aggregate metal oxide particles comprised of fused primary particles having an average aggregate particle diameter and an a

What is claimed is: 1. A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising (a) providing aggregate metal oxide particles comprised of fused primary particles having an average aggregate particle diameter and an average primary particle diameter, (b) pre-selecting a desired percent-reduction in the average aggregate particle diameter of the metal oxide particles to provide a pre-selected average aggregate particle diameter, (c) providing a dispersion standard pertaining to a dispersion of the aggregate metal oxide particles, wherein the dispersion standard correlates (i) the solids concentration of the dispersion with (ii) the percent-reduction in the aggregate particle diameter of the aggregate metal oxide particles that occurs when the dispersion is milled in a high-shear mixer, (d) determining a solids concentration that correlates to the pre-selected percent-reduction in the average aggregate particle diameter of the metal oxide particles by reference to the dispersion standard, (e) combining the aggregate metal oxide particles of step (a) with water to provide a dispersion having a solids concentration that is within 10% of the solids concentration determined in step (d), and (f) milling the dispersion in a high-shear milling device to provide a dispersion of aggregate metal oxide particles having about the pre-selected average aggregate particle diameter. 2. The method of claim 1 further comprising providing the dispersion standard by a method comprising (c-1) preparing three or more dispersions of metal oxide particles having the same particle diameter characteristics as the metal oxide particles of step (a), wherein each dispersion has a different solids concentration, (c-2) milling the dispersions in a high-shear mixer, (c-3) calculating the percent-reduction in average aggregate particle diameter for each dispersion by comparing the average aggregate particle diameter of each milled dispersion with the average aggregate particle diameter of the dispersion before milling, and (c-4) describing the correlation between the solids concentration of the dispersions and the percent-reduction in average aggregate particle diameter. 3. The method of claim 1, wherein the aggregate metal oxide particles are silica particles, alumina particles, ceria particles, or a mixture thereof. 4. The method of claim 3, wherein dispersion standard is provided by the following equation: L(wt. %)=[(% ΔDcirc ave)×(0.1 ln(dp)(nm)+0.2)]÷0.3, wherein L is the solids concentration of the dispersion, % ΔDcirc ave is the percent-reduction in average aggregate particle diameter, and dp is the average primary particle diameter of the aggregate metal oxide particles. 5. The method of claim 1, wherein the aggregate metal oxide particles are silica particles. 6. The method of claim 1, wherein the aggregate metal oxide particles are combined with the water by a method comprising (i) adding a first portion of the aggregate metal oxide particles to the water to provide a first aggregate metal oxide particle dispersion, (ii) milling the first aggregate metal oxide particle dispersion, (iii) adding a second portion of aggregate metal oxide particles to the first metal oxide particle dispersion to provide a second aggregate metal oxide particle dispersion, and (iv) milling the second aggregate metal oxide particle dispersion. 7. The method of claim 6, wherein the viscosity of the first aggregate metal oxide particle dispersion is reduced by about 5% or more before the addition of the second portion of aggregate metal oxide particles. 8. The method of claim 1, wherein the desired percent-reduction is about 10-60%. 9. The method of claim 1, wherein the aggregate metal oxide dispersion comprises about 0.02-2 mols of an acid per kilogram of aggregate metal oxide. 10. The method of claim 1, wherein the aggregate metal oxide dispersion comprises about 0.02-2 mols of a quaternary ammonium hydroxide per kilogram of aggregate metal oxide. 11. The method of claim 10, wherein the quaternary ammonium hydroxide has the formula (NR1R2R3R4)OH wherein each of R1, R2, R3, and R4 are independently selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, C2-C10 alkenyl, and aryl groups, any of which can be unsubstituted or substituted with C1-C10 alkyl, hydroxy, C1-C10 alkoxy, or aryl groups. 12. The method of claim 11, wherein each of R1, R2, R3 and R4 are independently C1-C3 alkyl groups. 13. The method of claim 12, wherein each of R1, R2, R3 and R4 are independently methyl or ethyl groups. 14. The method of claim 1, wherein the aggregate metal oxide particles are alumina particles. 15. The method of claim 14, wherein the dispersion comprises about 0.1 wt. % to about 1 wt. % of an acid. 16. The method of claim 1, wherein milling the aggregate metal oxide dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the metal oxide particles by about 20% or more. 17. The method of claim 1, wherein the aggregate metal oxide particle dispersion is milled in a high-shear blade-type mixer, and the mixer comprises a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfies the following equation: 18. A method of reducing the aggregate particle diameter of aggregate metal oxide particles comprising (a) providing aggregate metal oxide particles comprised of fused primary particles having an average aggregate particle diameter, (b) combining the aggregate metal oxide particles with water comprising an acid or a quaternary ammonium hydroxide to provide a dispersion having a viscosity (η), (c) milling the aggregate metal oxide particle dispersion in a high-shear blade-type mixer, wherein the mixer comprises a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfies the following equation: whereby the average aggregate particle diameter of the aggregate metal oxide particles is reduced. 19. The method of claim 18, wherein the aggregate metal oxide particles are combined with the water by a method comprising (i) adding a first portion of the aggregate metal oxide particles to the water to provide a first aggregate metal oxide particle dispersion, (ii) milling the first aggregate metal oxide particle dispersion, (iii) adding a second portion of aggregate metal oxide particles to the first metal oxide particle dispersion to provide a second aggregate metal oxide particle dispersion, and (iv) milling the second aggregate metal oxide particle dispersion. 20. The method of claim 19, wherein the viscosity of the first aggregate metal oxide particle dispersion is reduced by about 5% or more before the addition of the second portion of aggregate metal oxide particles. 21. The method of claim 18, wherein the number average aggregate particle diameter of the aggregate metal oxide particles is reduced by about 10% or more. 22. The method of claim 21, wherein the number average aggregate particle diameter of the aggregate metal oxide particles is reduced by about 20% or more. 23. The method of claim 18, wherein the aggregate metal oxide particles have an average primary particle diameter (dp), and the amount of aggregate metal oxide particles in the dispersion (L) satisfies the following equation: 80[0.1 ln(dp)(nm)+0.2]<L(wt. %)<100[0.1 ln(dp)(nm)+0.2]. 24. The method of claim 18, wherein the aggregate metal oxide particles are selected from the group consisting of silica, alumina, and ceria particles. 25. The method of claim 24, wherein the aggregate metal oxide particles are alumina particles. 26. The method of claim 25, wherein the dispersion comprises about 0.1 wt. % to about 1 wt.% of an acid. 27. The method of claim 24, wherein the aggregate metal oxide particles are silica particles. 28. The method of claim 18, wherein the aggregate metal oxide dispersion comprises about 0.02-2 mols of an acid per kilogram of aggregate metal oxide particles. 29. The method of claim 18, wherein the aggregate metal oxide dispersion comprises about 0.02-2 mols of a quaternary ammonium hydroxide per kilogram of aggregate metal oxide particles. 30. The method of claim 29, wherein the quaternary ammonium hydroxide has the formula (NR1R2R3R4)OH wherein each of R1, R2, R3, and R4 are independently selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, C2-C10 alkenyl, and aryl groups, any of which can be unsubstituted or substituted with C1-C10 alkyl, hydroxy, C1-C10 alkoxy, or aryl groups. 31. The method of claim 30, wherein each of R1, R2, R3 and R4 are independently C1-C3 alkyl groups. 32. The method of claim 31, wherein each of R1, R2, R3 and R4 are independently methyl or ethyl groups. 33. The method of claim 18, wherein milling the aggregate metal oxide dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the metal oxide particles by about 20% or more. 34. A method of reducing the aggregate particle diameter of aggregate silica particles comprising (a) providing aggregate silica particles comprising fused primary particles having an average aggregate particle diameter and having a BET surface area of about 135 m2/g or more (b) combining the aggregate silica particles with acidified or basified water in sufficient quantities to provide a dispersion comprising about 30-50 wt. % aggregate silica particles, and (c) milling the aggregate silica particle dispersion in a high-shear blade-type mixer, whereby the average aggregate particle diameter of the aggregate silica particles is reduced. 35. The method of claim 34, wherein the aggregate silica particles are combined with the acidified or basified water by a method comprising (i) adding a first portion of the aggregate silica particles to the acidified or basified water to provide a first aggregate silica particle dispersion, (ii) milling the first aggregate silica particle dispersion, (iii) adding a second portion of aggregate silica particles to the first metal oxide particle dispersion to provide a second aggregate silica particle dispersion, and (iv) milling the second aggregate silica particle dispersion. 36. The method of claim 35, wherein the viscosity of the first aggregate silica particle dispersion is reduced by about 5% or more before the addition of the second portion of aggregate silica particles. 37. The method of claim 34, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by about 10% or more. 38. The method of claim 37, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by about 20% or more. 39. The method of claim 34, wherein the dispersion comprises about 0.01-5 wt. % of an acid. 40. The method of claim 34, wherein the aggregate silica particles have an average primary particle diameter (dp), and the amount of aggregate silica particles in the dispersion (L) satisfies the following equation: 80[0.1 ln(dp)(nm)+0.2]<L(wt. %)<100[0.1 ln(dp)(nm)+0.2]. 41. The method of claim 34, wherein milling the aggregate silica dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the aggregate silica particles by about 20% or more. 42. The method of claim 34, wherein the aggregate silica dispersion has a viscosity (η), and the milling of the aggregate silica dispersion is performed using a high-shear blade-type mixer comprising a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfies the following equation: 43. A method of preparing a dispersion of aggregate metal oxide particles having a pre-selected average aggregate particle diameter comprising (a) providing aggregate metal oxide particles comprising fused primary particles having an average primary particle diameter (dp) and an average aggregate particle diameter (Dcirc ave), (b) pre-selecting a desired percent-reduction in the average aggregate particle diameter (% ΔDcirc ave) of about 10% to about 60% to provide a pre-selected average aggregate particle diameter, (c) combining the aggregate metal oxide particles with water to provide a dispersion of aggregate metal oxide particles, wherein the amount of aggregate metal oxide particles in the dispersion is within the range 0.8 L-1.2 L, and L is determined by the following equation: L(wt. %)=[(% ΔDcirc ave)×(0.1 ln(dp)(nm)+0.2)]÷0.3, and (d) milling the aggregate metal oxide particle dispersion using a high-shear mixer, whereby the aggregate particle diameter of the aggregate metal oxide particles is reduced to provide a dispersion of aggregate metal oxide particles having about the pre-selected average aggregate particle diameter. 44. The method of claim 43, wherein the aggregate metal oxide particles are silica particles, alumina particles, ceria particles, or a combination thereof. 45. The method of claim 44, wherein the aggregate metal oxide particles are silica. 46. The method of claim 45, wherein the aggregate silica particles are combined with the acidified water by a method comprising (i) adding a first portion of the aggregate silica particles to the acidified water to provide a first aggregate silica particle dispersion, (ii) milling the first aggregate silica particle dispersion, (iii) adding a second portion of aggregate silica particles to the first aggregate silica particle dispersion to provide a second aggregate silica particle dispersion, and (iv) milling the second aggregate silica particle dispersion. 47. The method of claim 46, wherein the viscosity of the first aggregate silica particle dispersion is reduced by about 5% or more before the addition of the second portion of aggregate silica particles. 48. The method of claim 45, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by about 10% or more. 49. The method of claim 48, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by about 20% or more. 50. The method of claim 45, wherein the dispersion comprises about 0.02-2 mols of an acid per kilogram of aggregate silica particles. 51. The method of claim 45, wherein milling the aggregate silica dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the aggregate silica particles by about 20% or more. 52. The method of claim 45, wherein the aggregate silica dispersion has a viscosity (η), and the milling of the aggregate silica dispersion is performed using a high-shear blade-type mixer, and the mixer comprises a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfies the following equation: 53. A method of reducing the aggregate particle diameter of aggregate silica particles comprising (a) combining aggregate silica particles comprising fused primary particles having an average aggregate particle diameter and a surface area of about 115 m2/g or more with water and a quaternary ammonium hydroxide in sufficient quantities to provide a dispersion comprising about 30 wt. % or more aggregate silica particles, and (b) milling the aggregate silica particles using a high-shear mixer, whereby the average aggregate particle diameter of the aggregate silica particles is reduced. 54. The method of claim 53, wherein the quaternary ammonium hydroxide has the formula (NR1R2R3R4)OH wherein each of R1, R2, R3, and R4 are independently selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, C2-C10 alkenyl, and aryl groups, any of which can be unsubstituted or substituted with C1-C10 alkyl, hydroxy, C1-C10 alkoxy, or aryl groups. 55. The method of claim 54, wherein each of R1, R2, R3, and R4 is independently a C1-C3 alkyl group. 56. The method of claim 55, wherein each of R1, R2, R3, and R4 is independently a methyl or ethyl group. 57. The method of claim 53, wherein the aggregate silica particles are combined with the water and quaternary ammonium hydroxide by a method comprising (i) adding a first portion of the aggregate silica particles to the water and quaternary ammonium hydroxide to provide a first aggregate silica particle dispersion, (ii) milling the first aggregate silica particle dispersion, (iii) adding a second portion of aggregate silica particles to the first aggregate silica particle dispersion to provide a second aggregate silica particle dispersion, and (iv) milling the second aggregate silica particle dispersion. 58. The method of claim 57, wherein the viscosity of the first aggregate silica dispersion is reduced by at about 5% or more before the addition of the second portion of aggregate silica particles. 59. The method of claim 53, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by at about 10% or more. 60. The method of claim 59, wherein the number average aggregate particle diameter of the aggregate silica particles is reduced by about 20% or more. 61. The method of claim 53, wherein the aggregate silica particles have an average primary particle diameter (dp), and the amount of aggregate silica particles in the dispersion (L) satisfies the following equation: 80[0.1 ln(dp)(nm)+0.2]<L(wt. %)<100[0.1 ln(dp)(nm)+0.2]. 62. The method of claim 53, wherein the dispersion comprises about 0.02-2 mols of the quaternary ammonium hydroxide per kilogram of aggregate silica particles. 63. The method of claim 53, wherein milling the aggregate silica dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the aggregate silica particles by about 20% or more. 64. The method of claim 53, wherein the aggregate silica dispersion has a viscosity (η), and the milling of the aggregate silica dispersion is performed using a high-shear blade-type mixer, and the mixer comprises a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfies the following equation: 65. A method of reducing the aggregate particle diameter of aggregate alumina particles comprising (a) combining aggregate alumina particles comprising fused primary particles with water and about 0.02-0.4 mols of an acid per kilogram of aggregate alumina particles to provide a dispersion comprising about 30 wt. % or more aggregate alumina particles, and (b) milling the dispersion using a high-shear mixer, whereby the aggregate particle diameter of the aggregate alumina particles are reduced. 66. The method of claim 65, wherein the aggregate alumina particles are combined with the acidified water by a method comprising (i) adding a first portion of the aggregate alumina particles to the acidified water to provide a first aggregate alumina particle dispersion, (ii) milling the first aggregate alumina particle dispersion, (iii) adding a second portion of aggregate alumina particles to the first metal oxide particle dispersion to provide a second aggregate alumina particle dispersion, and (iv) milling the second aggregate alumina particle dispersion. 67. The method of claim 66, wherein the viscosity of the first aggregate alumina dispersion is reduced by about 5% or more before the addition of the second portion of aggregate alumina particles. 68. The method of claim 65, wherein the number average aggregate particle diameter of the aggregate alumina particles is reduced by about 10% or more. 69. The method of claim 68, wherein the number average aggregate particle diameter of the aggregate alumina particles is reduced by about 20% or more. 70. The method of claim 65, wherein the aggregate alumina particles have an average primary particle diameter (dp), and the amount of aggregate alumina particles in the dispersion (L) satisfies the following equation: 80[0.1 ln(dp)(nm)+0.2]<L(wt. %)<100[0.1 ln(dp)(nm)+0.2]. 71. The method of claim 65, wherein the aggregate alumina particles have a surface area of about 110 m2/g or less. 72. The method of claim 65, wherein milling the aggregate alumina dispersion reduces the geometric standard deviation (σg (Dcirc)) of the aggregate particle diameter of the aggregate alumina particles by about 30% or more. 73. The method of claim 65, wherein the milling of the aggregate alumina dispersion is performed using a high-shear blade-type mixer, and the mixer has a blade having a radius (R), a characteristic blade length (X), and an angular velocity (ω) that satisfy the following equation: