Nano-scale metal halide scintillation materials and methods for making same

• US 7,625,502 B2
• Filed: 03/26/2007
• Issued: 12/01/2009
• Est. Priority Date: 03/26/2007
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Srivastava, Alok, Clothier, Brent Allen, Venkataramani, Venkat Subramaniam, Loureiro, Sergio Paulo Martins
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US11/728,399
• Publication Number:
  US 20080241040A1
• Time in Patent Office: 981 Days
• Field of Search: 252/301.4 H, 423/263, 423/43, 423/464, 423/489, 423/490, 423/491, 423/497, 977/775, 977/776, 977/834
• US Class Current: 252/301.40H
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 9/00 General methods of preparing halides particular individual halides, see the relevant groups in C01B - C01G according to the element combined with the halogen; electrolytic production of inorganic compounds C25B
• CPC Class Codes: C01B 9/02 Chlorides
• CPC Class Codes: C01B 9/04 Bromides
• CPC Class Codes: C01B 9/06 Iodides
• CPC Class Codes: C01B 9/08 Fluorides
• CPC Class Codes: C01D 3/00 Halides of sodium, potassium or alkali metals in general halides in general C01B9/00
• CPC Class Codes: C01F 11/22 Fluorides
• CPC Class Codes: C01F 17/253 Halides
• CPC Class Codes: C01F 17/259 Oxyhalides
• CPC Class Codes: C01G 1/06 Halides
• CPC Class Codes: C01G 11/02 Sulfides
• CPC Class Codes: C01G 9/08 Sulfides
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C09C 3/10 Treatment with macromolecular organic compounds C09C3/006 takes precedence
• CPC Class Codes: Y10S 977/775 Nanosized powder or flake, e.g. nanosized catalyst
• CPC Class Codes: Y10S 977/776 Ceramic powder or flake
• CPC Class Codes: Y10S 977/834 Optical properties of nanomaterial, e.g. specified transparency, opacity, or index of refraction

Abstract

Crystalline scintillator materials comprising nano-scale particles of metal halides are provided. The nano-scale particles are less than 100 nm in size. Methods are provided for preparing the particles. In these methods, ionic liquids are used in place of water to allow precipitation of the final product. In one method, the metal precursors and halide salts are dissolved in separate ionic liquids to form solutions, which are then combined to form the nano-crystalline end product. In the other methods, micro-emulsions are formed using ionic liquids to control particle size.

Claims

1. A method for making nano-scale particles of a halide based scintillation material, comprising:

combining a first solution comprising one or more metal salts and a second solution comprising one or more halide precursors to form nano-scale particles of a halide based scintillation material, wherein both the first solution and the second solution comprise ionic liquids; and

isolating the nano-scale particles from the combined first and second solutions.

2. The method of claim 1 wherein each ionic liquid comprises at least one cation selected from the group consisting of imidazoliums, pyridiniums, pyrrolidiniums, phosphoniums, tetra-alkyl ammoniums, and sulfoniums, and at least one anion selected from the group consisting of alkylsulfates, tosylates, methansulfonates, bis(trifluoromethylsulfonyl)imides, hexafluorophosphates, tetrafluoroborates, and halides.

3. The method of claim 1 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanoids, group 1 elements, group 2 elements, group 3 elements, group 13 elements, group 14 elements, and group 15 elements.

4. The method of claim 1 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanum, cerium, praseodymium, terbium, and thallium.

5. The method of claim 1 wherein the one or more halide precursors comprise at least halide species of the general formula NR₄Y;

wherein each R is independently selected from the group consisting of hydride, alkyl, aryl, and halide; and

Y comprises an anion selected from the group consisting of fluoride, chloride, bromide, iodide, and combinations thereof.

6. The method of claim 1 wherein the nano-scale particles of the scintillation material comprise a phosphor having a general formula of MX_n:

Y;

wherein M comprises at least one metal ion selected from the group consisting of La, Na, K, Rb, and Cs;

X comprises at least one halide ion selected from the group consisting of F, Cl, Br, and I;

Y comprises at least one metal ion selected from the group consisting of Tl, Tb, Na, Ce, Pr, and Eu; and

n is an integer between 1 and 4, inclusive.

7. The method of claim 1 wherein the nano-scale particles of the scintillation material comprise a phosphor having the general formula [La₍₁₋

x)Ce_x][Cl<sub>(1−

y−

z)</sub>Br<sub>(y−

z)</sub>I_z]₃;

wherein 0≦

x≦

1;

0≦

(1−

y−

z)≦

1;

0≦

z≦

1; and

0≦

(y−

z)≦

1.

8. The method of claim 1 wherein the nano-scale particles of the scintillation material comprise at least one phosphor having a general formula selected form the group consisting of LaCl₃:

Ce, RbGd₂F₇;

Ce, CeF₃, BaF₂, CsI;

Na, CaF₂;

Eu, LiI;

Eu, CsI, CsF, CsI;

Tl, and NaI;

Tl.

9. The method of claim 1 wherein the nano-scale particles of the halide based scintillator material are less than about 100 nm in size.

10. A method for making nano-scale particles of a halide based scintillation material, comprising:

making a micro-emulsion;

forming nano-scale particles of a halide based scintillation material in the micro-emulsion, wherein the nano-scale particles are formed by bubbling a hydrogen halide gas through the micro-emulsion; and

isolating the particles from the micro-emulsion.

11. The method of claim 10 wherein making the micro-emulsion comprises

adding a surfactant to an organic solvent to form a surfactant solution;

dissolving one or more metal salts in an ionic liquid to form an ionic solution; and

mixing the surfactant solution with the ionic solution to form the micro-emulsion.

12. The method of claim 11 wherein the surfactant comprises at least one material selected from the group consisting of an aromatic ethoxylate, a polyethylene glycol dodecyl ether, a sorbitan-fatty acid ester surfactant, a polyoxyethylenesorbitan fatty acid ester surfactant, and an alkylphenol.

13. The method of claim 11 wherein the organic solvent is selected from the group consisting of an alkyl solvent and an aryl solvent.

14. The method of claim 11 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanoids, group 1 elements, group 2 elements, group 3 elements, group 13 elements, group 14 elements, and group 15 elements.

15. The method of claim 11 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanum, cerium, praseodymium, terbium, and thallium.

16. The method of claim 11 wherein the ionic liquid comprises at least one cation selected from the group consisting of imidazoliums, pyridiniums, pyrrolidiniums, phosphoniums, tetra-alkyl ammoniums, and sulfoniums, and at least one anion selected from the group consisting of alkylsulfates, tosylates, methansulfonates, bis(trifluoromethylsulfonyl)imides, hexafluorophosphates, tetrafluoroborates, and halides.

17. The method of claim 10 wherein the nano-scale particles of the scintillation material comprise a phosphor having a general formula of MX_n:

Y;

wherein M comprises at least one metal ion selected from the group consisting of La, Na, K, Rb, and Cs;

X comprises at least one halide ion selected from the group consisting of F, Cl, Br, and I;

Y comprises at least one metal ion selected from the group consisting of Tl, Tb, Na, Ce, Pr, and Eu; and

n is an integer between 1 and 4, inclusive.

18. The method of claim 10 wherein the nano-scale particles of the scintillation material comprise a phosphor having the general formula [La₍₁₋

x)Ce_x][Cl<sub>(1−

y−

z)</sub>Br<sub>(y−

z)</sub>I_z]₃;

wherein 0≦

x≦

1;

0≦

(1−

y−

z)≦

1;

0≦

z≦

1; and

0≦

(y−

z)≦

1.

19. The method of claim 10 wherein the nano-scale particles of the halide based scintillation material are less than about 100 nm in size.

20. A method for making nano-scale particles of a halide based scintillation material, comprising:

making a first micro-emulsion;

adding a solution comprising one or more metal organic salts to the first micro-emulsion to form a second micro-emulsion; and

isolating the nano-scale particles of the halide based scintillation material from the second micro-emulsion.

21. The method of claim 20 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanoids, group 1 elements, group 2 elements, group 3 elements, group 13 elements, group 14 elements, and group 15 elements.

22. The method of claim 20 wherein the one or more organic metal salts comprise at least one metal anion selected from the group consisting of lanthanum, cerium, praseodymium, terbium, and thallium, and a cation of the general formula OR wherein R is an alkyl group of one to ten carbons.

23. The method of claim 20 wherein the solution comprises an organic solvent selected from the group consisting of an alkyl solvent and an aryl solvent.

24. The method of claim 20 wherein making the first micro-emulsion comprises

adding a surfactant to a second organic solvent to form a surfactant solution;

dissolving one or more halide salts in an ionic liquid to form an ionic solution; and

mixing the surfactant solution with the ionic solution to form a micro-emulsion.

25. The method of claim 24 wherein the surfactant comprises at least one of an aromatic ethoxylate, a polyethylene glycol dodecyl ether, a sorbitan-fatty acid ester surfactant, a polyoxyethylenesorbitan fatty acid ester surfactant, or an alkylphenol.

26. The method of claim 24 wherein the second organic solvent is selected from the group consisting of an alkyl solvent and an aryl solvent.

27. The method of claim 24 wherein the halide salts comprise at least halide species of the general formula NR₄ Y;

wherein each R is independently selected from the group consisting of hydride, alkyl, aryl, and halide; and

Y comprises an anion selected from the group consisting of fluoride, chloride, bromide, iodide, and combinations thereof.

28. The method of claim 24 wherein the first ionic liquid comprises at least one cation selected from the group consisting of imidazoliums, pyridiniums, pyrrolidiniums, phosphoniums, tetra-alkyl ammoniums, and sulfoniums, and at least one anion selected from the group consisting of alkylsulfates, tosylates, methansulfonates, bis(trifluoromethylsulfonyl)imides, hexafluorophosphates, tetrafluoroborates, and halides.

29. The method of claim 20 wherein the nano-scale particles of the scintillation material comprise a phosphor having a general formula of MX_n:

Y;

wherein M comprises at least one metal ion selected from the group consisting of La, Na, K, Rb, and Cs;

X comprises at least one halide ion selected from the group consisting of F, Cl, Br, and I;

Y comprises at least one metal ion selected from the group consisting of Tl, Tb, Na, Ce, Pr, and Eu; and

n is an integer between 1 and 4, inclusive.

30. The method of claim 20 wherein the nano-scale particles of the scintillation material comprise a phosphor having the general formula [La₍₁₋

x)Ce_x][Cl<sub>(1−

y−

z)</sub>Br<sub>(y−

z)</sub>I_z]₃;

wherein 0≦

x≦

1;

0≦

(1−

y−

z)≦

1;

0≦

z≦

1; and

0≦

(y−

z)≦

1.

31. The method of claim 20 wherein the nano-scale particles of the scintillation material comprise at least one phosphor having a general formula selected from the group consisting of LaCl₃:

Ce, RbGd₂F₇;

Ce, CeF₃, BaF₂, CsI;

Na, CaF₂;

Eu, LiI;

Eu, CsI, CsF, CsI;

Tl, and NaI;

Tl.

32. The method of claim 20 wherein the nano-scale particles of the halide based scintillater material are less than about 100 nm in size.

33. A method for making nano-scale particles of a halide based scintillation material, comprising the steps of

forming a first micro-emulsion comprising:

dissolving a first surfactant in a first organic solvent to form a first surfactant solution;

dissolving one or more halide salts in a first ionic liquid to form a first solution; and

mixing the first solution with the first surfactant solution to form the first micro-emulsion;

forming a second micro-emulsion;

combining the first micro-emulsion with the second micro-emulsion to form a combined micro-emulsion; and

isolating the nano-scale particles of the halide based scintillation materials from the combined micro-emulsion.

34. The method of claim 33 wherein the first surfactant comprises at least one of an aromatic ethoxylate, a polyethylene glycol dodecyl ether, a sorbitan-fatty acid ester surfactant, a polyoxyethylenesorbitan fatty acid ester surfactant, or an alkylphenol.

35. The method of claim 33 wherein the first organic solvent is selected from the group consisting of an alkyl solvent and an aryl solvent.

36. The method of claim 33 wherein the one or more halide salts comprise at least halide species of the general formula NR₄ Y;

wherein each R is independently selected from the group consisting of hydride, alkyl, aryl, and halide; and

Y comprises an anion selected from the group consisting of fluoride, chloride, bromide, iodide, and combinations thereof.

37. The method of claim 33 wherein the first ionic liquid comprises at least one cation selected from the group consisting of imidaoliums, pyridiniums, pyrrolidiniums, phosphoniums, tetra-alkyl ammoniums, and sulfoniums, and at least one anion selected from the group consisting of alkylsulfates, tosylates, methansulfonates, bis(trifluoromethylsulfonyl)imides, hexafluorophosphates, tetrafluoroborates, and halides.

38. The method of claim 33 wherein forming the second micro-emulsion comprises:

adding a second surfactant to a second organic solvent to form a second surfactant solution;

dissolving one or more metal salts in a second ionic liquid to form a second solution; and

mixing the second solution with the second surfactant solution to form a second micro-emulsion.

39. The method of claim 38 wherein the second surfactant comprises at least one of an aromatic ethoxylate, a polyethylene glycol dodecyl ether, a sorbitan-fatty acid ester surfactant, a polyoxyethylenesorbitan fatty acid ester surfactant, or an alkylphenol.

40. The method of claim 38 wherein the second organic solvent is selected from the group consisting of an alkyl solvent or an aryl solvent.

41. The method of claim 38 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanoids, group 1 elements, group 2 elements, group 3 elements, group 13 elements, group 14 elements, and group 15 elements.

42. The method of claim 38 wherein the one or more metal salts comprise at least one metal anion selected from the group consisting of lanthanum, cerium, praseodymium, terbium, and thallium.

43. The method of claim 38 wherein the second ionic liquid comprises at least one cation selected from the group consisting of imidazoliums, pyridiniums, pyrrolidiniums, phosphoniums, tetra-alkyl ammoniums, and sulfoniums, and at least one anion selected from the group consisting of alkylsulfates, tosylates, methansulfonates, bis(trifluoromethylsulfonyl)imides, hexafluorophosphates, tetrafluoroborates, and halides.

44. The method of claim 33 wherein the nano-scale particles of the scintillation material comprise a phosphor having a general formula of MX_n:

Y;

wherein M comprises at least one metal ion selected from the group consisting of La, Na, K, Rb, and Cs;

X comprises at least one halide ion selected from the group consisting of F, Cl, Br, and I;

Y comprises at least one metal ion selected from the group consisting of Tl, Tb, Na, Ce, Pr, and Eu; and

n is an integer between 1 and 4, inclusive.

45. The method of claim 33 wherein the nano-scale particles of the scintillation material comprise a phosphor having the general formula [La₍₁₋

x)Ce_x][Cl<sub>(1−

y−

z)</sub>Br<sub>(y−

z)</sub>I_z]₃;

wherein 0≦

x≦

1;

0≦

(1−

y−

z)≦

1;

0≦

z≦

1; and

0≦

(y−

z)≦

1.

46. The method of claim 33 wherein the nano-scale particles of the scintillation material comprise at least one phosphor having a general formula selected from the group consisting of LaCl₃:

Ce, RbGd₂F₇;

Ce, CeF₃, BaF₂, CsI;

Na, CaF₂;

Eu, LiI;

Eu, CsI, CsF, CsI;

Tl, and NaI;

Tl.

47. The method of claim 33 wherein the nano-scale particles of the halide based scintillator material are less than about 100 nm in size.