Fabrication of transparent ceramics using nanoparticles

• US 8,268,230 B2
• Filed: 05/21/2007
• Issued: 09/18/2012
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Inventors: Cherepy, Nerine J., Tillotson, Thomas M., Kuntz, Joshua D., Payne, Stephen A.
• Primary Examiner(s): Daniels, Matthew
• Assistant Examiner(s): KEMMERLE III, RUSSELL J
• Application Number:
  US11/805,275
• Publication Number:
  US 20080090716A1
• Time in Patent Office: 1,947 Days
• Field of Search: 264/621, 501/12
• US Class Current: 264/621
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 13/324 by solid combustion synthesis
• CPC Class Codes: C01F 17/34 Aluminates, e.g. YAlO3 or Y3-xGdxAl5O12
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/443 Nitrates or nitrites
• CPC Class Codes: C04B 2235/449 Organic acids, e.g. EDTA, citrate, acetate, oxalate
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/6027 Slip casting
• CPC Class Codes: C04B 2235/6581 Total pressure below 1 atmosphere, e.g. vacuum
• CPC Class Codes: C04B 2235/661 Multi-step sintering
• CPC Class Codes: C04B 2235/762 Cubic symmetry, e.g. beta-SiC
• CPC Class Codes: C04B 2235/764 Garnet structure A3B2(CO4)3
• CPC Class Codes: C04B 2235/9653 Translucent or transparent ceramics other than alumina
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/624 Sol-gel processing
• CPC Class Codes: C04B 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C04B 35/6455 Hot isostatic pressing

Abstract

A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

Claims

1. A method of making a transparent ceramic, comprising the steps of:

providing metal salts,

dissolving said metal salts to produce an aqueous salt solution,

adding an organic chelating agent to produce a complexed-metal sol,

heating said complexed-metal sol to produce a gel,

drying said gel to produce a powder,

synthesizing nanoparticles by combusting said powder to produce said nano-particles,

calcining said nano-particles to produce oxide nano-particles,

forming said oxide nano-particles into a green body, and

sintering said green body to produce the transparent ceramic.

2. The method of claim 1 wherein said step of providing metal salts comprises providing nitrate, chloride, acetate, acetylacetonate, or carbonate metal salts or a combination thereof.

3. The method of claim 1 wherein said step of adding an organic chelating agent to produce a complexed-metal the chelating agent is a tri-dentate organic species.

4. The method of claim 1 wherein said step of adding an organic chelating agent to produce a complexed-metal sol comprises adding oxalic, malic, polygalacturonic, tannic, fulvic, tartaric, succinic, pyruvic or other tri-dentate organic species organic chelating agent.

5. The method of claim 1 wherein said step of adding an organic chelating agent to produce a complexed-metal sol comprises adding citric acid as an organic chelating agent to produce a complexed-metal sol.

6. The method of claim 1 wherein said step of drying said gel to produce a powder comprises drying said gel in a vacuum to produce a powder.

7. The method of claim 1 wherein said step of combusting said powder to produce nano-particles comprises heating said powder in air at 300-600°

C.

8. The method of claim 1 wherein said step of calcining said nano-particles to produce oxide nano-particles comprises combusting said powder by heating said nano-particles in air at 600-1200°

C. to produce oxide nano-particles.

9. The method of claim 1 wherein said step of forming said oxide nano-particles into a green body comprises uniaxial pressing, cold isostatic pressing, or slip casting said oxide nano-particles to form a green body.

10. The method of claim 1 wherein said step of sintering said green body to produce the transparent ceramic comprises vacuum sintering, controlled atmosphere sintering, pulsed-electric current sintering, plasma sintering, microwave sintering, laser sintering, radio-frequency sintering, or hot-pressing said green body to produce the transparent ceramic.

11. The method of fabricating a transparent ceramic of claim 1 wherein said step of sintering said green body to produce the transparent ceramic comprises vacuum sintering said green body for 2-12 hours at 1700-1900°

C. to produce the transparent ceramic.

12. The method of claim 1 wherein said steps of forming said oxide nano-particles into a green body and sintering said green body comprise:

(a) green body formation via uniaxial pressing, cold isostatic pressing, or slip casting,

(b) followed by consolidation via vacuum sintering, controlled atmosphere sintering, pulsed-electric current sintering, plasma sintering, microwave sintering, laser sintering, radio-frequency sintering, or hot-pressing, and

(c) subsequent hot isostatic pressing to improve clarity, or any combination thereof.

13. The method of fabricating a transparent ceramic of claim 1 wherein the transparent ceramic has a cubic garnet structure including Lu₃Al₅O₁₂, Y₃Al₅O₁₂, Gd₃Al₅O₁₂ and related materials, (A_1-x, B_x, etc.)₃(C_1-y, D_y, etc.)₅O₁₂ where first site (A, B, etc.) can contain any mixture of the following that results in the garnet structure:

Y, Gd, Lu, La, Tb, Pr; and

the second site (C, D, etc.) site can contain any mixture of the following that results in the garnet structure;

Al, Ga, Sc.

14. The method of fabricating a transparent ceramic of claim 1 wherein said step of dissolving said metal salts to produce an aqueous salt solution includes stirring said metal salts to produce an aqueous salt solution.

15. The method of fabricating a transparent ceramic of claim 1 wherein said step of heating said complexed-metal sol to produce a gel includes stirring said complexed-metal sol to produce a gel.

16. A method of fabricating a transparent ceramic, comprising the steps of:

providing metal salts,

dissolve and stir said metal salts to produce an aqueous salt solution,

add an organic chelating agent to produce a complexed-metal sol,

heat and stir said complexed-metal sol to produce a gel,

dry said gel to produce a powder,

synthesize nanoparticles by combusting combust said powder in air to produce said nano-particles,

calcine said nano-particles in air to produce oxide nanoparticles,

form said oxide nano-particles in to a green body, and

sinter said green body to produce the transparent ceramic.

17. The method of fabricating a transparent ceramic of claim 16 wherein said step of providing metal salts is providing nitrate, chloride, or nitrate and chloride metal salts.

18. The method of fabricating a transparent ceramic of claim 16 wherein said organic chelating agent is citrate.

19. The method of fabricating a transparent ceramic of claim 16 wherein said organic chelating agent is citric acid.

20. The method of fabricating a transparent ceramic of claim 16 wherein said organic chelating agent is the oxalic, malic, polygalacturonic, tannic, fulvic, tartaric, succinic, pyruvic, or other tri-dentate organic species.

21. The method of fabricating a transparent ceramic of claim 16 wherein said step of combusting said powder in air comprises heating said powder in air at 300-600°

C.

22. The method of fabricating a transparent ceramic of claim 16 wherein said step of calcine said powder in air to produce oxide nano-particles comprises calcine said powder in air at 600-1200°

C. to produce said oxide nano-particles.

23. The method of fabricating a transparent ceramic of claim 16 wherein said step of sinter comprises vacuum sintering for 2-12 hours at 1700-1900°

C. to produce a transparent ceramic.

24. The method of fabricating a transparent ceramic of claim 16 wherein said steps of forming a green body and sintering said green body comprise:

(a) green body formation via uniaxial pressing, cold isostatic pressing, or slip casting,

(b) followed by consolidation via vacuum sintering, controlled atmosphere sintering, pulsed-electric current sintering, plasma sintering, microwave sintering, laser sintering, radio-frequency sintering, or hot-pressing, and

(c) subsequent hot isostatic pressing to improve clarity, or any combination thereof.

25. A method of fabricating a transparent oxide ceramic scintillator, comprising the steps of:

providing metal salts,

dissolve and stir said metal salts to produce an aqueous salt solution,

add an organic chelating agent to produce a complexed-metal sol,

heat and stir said complexed-metal sol to produce a gel,

dry said gel to produce a powder,

synthesize nanoparticles by combusting said powder in air to produce said nano-particles,

calcine said nano-particles in air to produce oxide nanoparticles,

form said oxide nano-particles in to a green body, and

sinter said green body to produce the transparent oxide ceramic scintillator.

26. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of providing metal salts comprises providing nitrate, chloride, acetate, acetylacetonate, or carbonate metal salts or a combination thereof.

27. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein in said step of adding an organic chelating agent to produce a complexed-metal, the chelating agent is a tri-dentate organic species such as oxalic, malic, polygalacturonic, tannic, fulvic, tartaric, succinic, pyruvic, or other organic species.

28. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of adding an organic chelating agent to produce a complexed-metal the chelating agent is oxalic, malic, polygalacturonic, tannic, fulvic, tartaric, succinic, pyruvic or other tri-dentate organic species.

29. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of adding an organic chelating agent to produce a complexed-metal sol comprises adding citric acid to produce a complexed-metal sol.

30. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of drying said gel to produce a powder comprises drying said gel in a vacuum to produce a powder.

31. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of combusting said powder to produce nano-particles comprises heating said powder in air at 300-600°

C.

32. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of calcining said nano-particles to produce oxide nano-particles comprises heating said nano-particles in air at 600-1200°

C. to produce oxide nano-particles.

33. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of forming said oxide nano-particles into a green body comprises uniaxial pressing, cold isostatic pressing, or slip casting said oxide nano-particles to form a green body.

34. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of sintering said green body to produce the transparent ceramic comprises vacuum sintering, controlled atmosphere sintering, pulsed-electric current sintering, plasma sintering, microwave sintering, laser sintering, radio-frequency sintering, or hot-pressing said green body to produce the transparent ceramic.

35. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said step of sintering said green body to produce the transparent ceramic comprises vacuum sintering for 2-12 hours at 1700-1900°

C. to produce the transparent ceramic.

36. The method of fabricating a transparent oxide ceramic scintillator of claim 25 wherein said steps of forming said oxide nano-particles into a green body and sintering said green body comprise:

(a) green body formation via uniaxial pressing, cold isostatic pressing, or slip casting,

(b) followed by consolidation via vacuum sintering, controlled atmosphere sintering, pulsed-electric current sintering, plasma sintering, microwave sintering, laser sintering, radio-frequency sintering, or hot-pressing, and

(c) subsequent hot isostatic pressing to improve clarity, or any combination thereof.

37. The method of fabricating a transparent oxide ceramic scintillator of claim 25, including the step of:

activating said transparent oxide ceramic scintillator using Ce or Pr.

38. The method of fabricating a transparent oxide ceramic scintillator of claim 25, including the step of:

activating said transparent oxide ceramic scintillator using Bi, Eu, Tb, Gd, Sm, Er, Nd.