METAL OXIDE NANOCRYSTALS: PREPARATION AND USES

• US 20100135937A1
• Filed: 09/24/2009
• Published: 06/03/2010
• Est. Priority Date: 03/26/2007
• Status: Abandoned Application

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Chen, Zhuoying, Huang, Limin, Jia, Zhang, Kymissis, Ioannis, O'Brien, Stephen
• Application Number:
  US12/566,135
• Publication Number:
  US 20100135937A1
• Time in Patent Office: Days
• US Class Current: 424/59
• CPC Class Codes: A61K 2800/413 Nanosized, i.e. having sizes below 100 nm
• CPC Class Codes: A61K 8/02 characterised by special physical form
• CPC Class Codes: A61K 8/27 Zinc; Compounds thereof
• CPC Class Codes: A61Q 17/04 Topical preparations for affording protection against sunlight or other radiation; Topical sun tanning preparations
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: C01B 13/32 by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
• CPC Class Codes: C01D 15/00 Lithium compounds
• CPC Class Codes: C01D 15/02 Oxides; Hydroxides
• CPC Class Codes: C01G 1/02 Oxides
• CPC Class Codes: C01G 19/00 Compounds of tin
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01G 25/00 Compounds of zirconium
• CPC Class Codes: C01G 25/006 Compounds containing, besides zirconium, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01G 3/006 Compounds containing, besides copper, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01G 33/00 Compounds of niobium
• CPC Class Codes: C01G 45/02 Oxides; Hydroxides
• CPC Class Codes: C01G 45/1264 containing rare earth, e.g. La1-xCaxMnO3, LaMnO3
• CPC Class Codes: C01G 49/0018 Mixed oxides or hydroxides, C01G49/0009 takes precedence
• CPC Class Codes: C01G 49/0054 : containing one rare earth metal, yttrium or scandium
• CPC Class Codes: C01G 51/70 : containing rare earth, e.g. LaCoO3 C01G51/68 takes precedence
• CPC Class Codes: C01P 2002/34 : perovskite-type (ABO3)
• CPC Class Codes: C01P 2002/72 : by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2002/82 : by IR- or Raman-data
• CPC Class Codes: C01P 2002/86 : by NMR- or ESR-data
• CPC Class Codes: C01P 2004/04 : obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/51 : Particles with a specific particle size distribution
• CPC Class Codes: C01P 2004/64 : Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/40 : Electric properties
• CPC Class Codes: H01G 11/22 : Electrodes
• CPC Class Codes: H01G 11/46 : Metal oxides
• CPC Class Codes: H01L 21/02172 : the material containing at least one metal element, e.g. metal oxides, metal nitrides, metal oxynitrides or metal carbides materials containing silicon H01L21/02123; metal silicates H01L21/02142
• CPC Class Codes: H01L 21/02181 : the material containing hafnium, e.g. HfO2
• CPC Class Codes: H01L 21/02183 : the material containing tantalum, e.g. Ta2O5
• CPC Class Codes: H01L 21/02186 : the material containing titanium, e.g. TiO2
• CPC Class Codes: H01L 21/02189 : the material containing zirconium, e.g. ZrO2
• CPC Class Codes: H01L 21/02192 : the material containing at least one rare earth metal element, e.g. oxides of lanthanides, scandium or yttrium
• CPC Class Codes: H01L 21/02197 : the material having a perovskite structure, e.g. BaTiO3
• CPC Class Codes: H01L 21/02205 : the layer being characterised by the precursor material for deposition
• CPC Class Codes: H01L 21/02282 : liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
• CPC Class Codes: H01L 21/31691 : with perovskite structure
• CPC Class Codes: H01L 28/40 : Capacitors
• CPC Class Codes: H01L 29/4908 : for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/516 : with at least one ferroelectric layer
• CPC Class Codes: H10K 10/472 : the gate dielectric comprising only inorganic materials
• CPC Class Codes: Y02E 60/13 : Energy storage using capacitors

Abstract

Nanocrystalline forms of metal oxides, including binary metal oxide, perovskite type metal oxides, and complex metal oxides, including doped metal oxides, are provided. Methods of preparation of the nanocrystals are also provided. The nanocrystals, including uncapped and uncoated metal oxide nanocrystals, can be dispersed in a liquid to provide dispersions that are stable and do not precipitate over a period of time ranging from hours to months. Methods of preparation of the dispersions, and methods of use of the dispersions in forming films, are likewise provided. The films can include an organic, inorganic, or mixed organic/inorganic matrix. The films can be substantially free of all organic materials. The films can be used as coatings, or can be used as dielectric layers in a variety of electronics applications, for example as a dielectric material for an ultracapacitor, which can include a mesoporous material. Or the films can be used as a high-K dielectric in organic field-effect transistors. In various embodiments, a layered gate dielectric can include spin-cast (e.g., 8 nm-diameter) high-K BaTiO₃ nanocrystals and parylene-C for pentacene OFETs.

Claims

1. A nanocrystalline form of a metal oxide, the form comprising a plurality of nanocrystals, the plurality of nanocrystals having a narrow size distribution and an average particle diameter ranging from about 1 nm to about 100 nm, the nanocrystals comprising a metal oxide of formula M¹_xO_z, a mixed metal oxide of the perovskite type of formula M²M³O₃, or a complex mixed metal oxide of the formula M⁴_xM⁵_yO_z, wherein all of M¹-M⁵ are independently selected ions of metallic elements.

2. The nanocrystalline form of claim 1 wherein the narrow size distribution is a substantially monodisperse size distribution.

3. The nanocrystalline form of claim 1 further comprising ions of additional metallic elements other than M¹-M⁵ in a crystal lattice of the metal oxide, mixed metal oxide, or complex mixed metal oxide.

4. The nanocrystalline form of claim 3 wherein the ions of additional metallic elements comprise ions of zirconium, yttrium, or rare earth metals.

5. The nanocrystalline form of claim 1 wherein an organic coating material is disposed on a surface of the nanocrystals to provide capped or coated nanocrystals.

6. The nanocrystalline form of claim 1 wherein the nanocrystals comprise a metal oxide of formula M¹_xO_z.

7. The nanocrystalline form of claim 6 wherein M¹ is titanium, zirconium, hafnium, vanadium, niobium, tantalum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, gallium, indium, tin or cerium.

8. The nanocrystalline form of claim 6 wherein x is 1 to about 3 and z is 1 to about 6.

9. The nanocrystalline form of claim 6 comprising zinc oxide, titanium oxide, or zirconium oxide.

10. The nanocrystalline form of claim 1 wherein the nanocrystals comprise a mixed metal oxide of the perovskite type of formula M²M³O₃.

11. The nanocrystalline form of claim 10 wherein M² comprises barium, strontium, calcium, lithium, lead, yttrium, bismuth, lanthanum, or a rare earth metal, or wherein M³ comprises titanium, zirconium, iron, copper, manganese, cerium, or cobalt;

or both.

12. The nanocrystalline form of claim 10 comprising barium titanate, strontium titanate, calcium titanate, barium strontium titanate, barium lanthanum, lithium lanthanum titanate, lead titanate, lead zirconium titanate, barium zirconate, lead zirconate, yttrium ferrite, bismuth ferrite, yttrium barium copper oxide, lanthanum manganese oxide, strontium cerium oxide, or a rare earth cobalt oxide or any combination thereof.

13. The nanocrystalline form of claim 1 wherein the nanocrystals comprise a complex metal oxide of the formula M⁴_xM⁵_yO_z.

14. The nanocrystalline form of claim 13 wherein M⁴ comprises indium, lithium, bismuth or yttrium, or wherein M⁵ comprises tin, niobium, or iron;

or both.

15. The nanocrystalline form of claim 13 wherein x is 1 to about 3, y is 1 to about 5, or z is 3 to about 12, or any combination thereof.

16. The nanocrystalline form of claim 13 comprising indium tin oxide, lithium niobium oxide, or a garnet, or any combination thereof.

17. The nanocrystalline form of claim 5 wherein the organic coating material comprises an alkanoic acid, a saturated or unsaturated fatty acid, decanoic acid, oleic acid, an alkylamine, a fatty amine, oleylamine, an alkanol, a fatty alcohol, or oleyl alcohol, or a combination thereof.

18. A method of preparation of the metal oxide nanocrystalline form of claim 1, comprising contacting an metalorganic precursor, wherein the metalorganic precursor comprises a single metallic element or more than one metallic element, and a liquid substance comprising an alcohol at an elevated temperature of less than about 350°

C., to provide the plurality of metal oxide nanocrystals having a narrow size distribution.

19. The method of claim 18 wherein the metalorganic precursor comprises a metal alkoxide, a metal carboxylate, or a metal complex such as a metal acetoacetonate.

20. The method of claim 18 further comprising, after contacting the metalorganic precursor and the liquid substance, then, contacting with a reagent, then, collecting the plurality of metal oxide nanocrystals, wherein collecting comprises centrifuging.

21. The method of claim 18 wherein the metalorganic precursor comprises a metallic element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, gallium, indium, tin and cerium, and, optionally, further comprises a second metallic element selected from the group consisting of barium, strontium, calcium, lithium, lead, yttrium, bismuth, lanthanum, a rare earth metal, titanium, zirconium, iron, copper, manganese, cerium, and cobalt.

22. The method of claim 21 wherein the metalorganic precursor comprises titanium and barium.

23. The method of claim 18 wherein the metalorganic precursor comprises a titanium alkoxide, titanium acetate, or titanium acetoacetonate and a barium alkoxide, barium acetate, or barium acetoacetonate.

24. The method of claim 18 wherein the liquid substance comprises water, or aqueous alkali, aqueous sodium hydroxide, aqueous potassium hydroxide, or tetrapropylammonium hydroxide.

25. The method of claim 18 comprising forming the metal oxide precursor solution by contacting a first metal alkoxide and a second metal alkoxide and a liquid substance comprising an alcohol at an elevated temperature of less than about 350°

C. to form the nanocrystalline form.

26. The method of claim 25 further comprising, after contacting the first metal alkoxide and second metal alkoxide and the liquid substance comprising an alcohol at an elevated temperature of less than about 350°

C., then, contacting with a reagent.

27. The method of claim 26 wherein an amount of the reagent added to the metal oxide precursor solution comprises up to about 20% of a volume of the precursor solution.

28. The method of claim 26 wherein the reagent comprises ethanol, isopropanol, or water, or any combination thereof.

29. The method of claim 26 wherein the reagent comprises an alkali, sodium hydroxide, or potassium hydroxide, or tetrapropylammonium hydroxide.

30. The method of any claim 18 wherein the elevated temperature is about 80°

C. to about 230°

C.

31. The method of claim 18 wherein the metalorganic precursor and liquid substance comprising an alcohol are contacted under a pressure of about 20 atm to about 30 atm.

32. The method of claim 18 further comprising contacting the metalorganic precursor and the liquid substance with an organic coating material.

33. The method of claim 32 wherein the organic coating material comprises an alkanoic acid, a saturated or unsaturated fatty acid, decanoic acid, oleic acid, an alkylamine, a fatty amine, oleylamine, an alkanol, a fatty alcohol, or oleyl alcohol, or a combination thereof.

34. The method of claim 18 comprising a method of preparation of a plurality of nanocrystals comprising BaTiO₃, the plurality having a narrow size distribution and an average nanocrystal diameter of about 2-80 nm, the method comprising:

contacting a barium metalorganic precursor and a titanium alkoxide to provide a bimetallic precursor solution;

then,

contacting the bimetallic precursor solution and a liquid substance comprising an alcohol at an elevated temperature of less than about 350°

C. for a period of time to provide the plurality of nanocrystals comprising BaTiO₃.

35. The method of claim 34 comprising dissolving barium metal in an alcohol to provide the barium metalorganic precursor, wherein alcohol is benzyl alcohol, ethanol, or isopropanol.

36. The method of claim 34 wherein the barium metalorganic precursor is barium ethoxide, barium isopropoxide, or barium benzyloxide.

37. The method of claim 34 wherein the titanium alkoxide comprises titanium isopropoxide.

38. The method of claim 34 wherein the liquid substance further comprising an organic coating material comprising a hydrophobic long chain amine, oleylamine, a fatty acid, oleic acid, decanoic acid, a fatty alcohol, oleyl alcohol, or any combination thereof.

40. A substantially homogeneous dispersion of the nanocrystalline form of claim 1 in a liquid.

41. A substantially homogeneous dispersion of a nanocrystalline form prepared by the method of claim 18 in a liquid.

42. The dispersion of claim 40 wherein the nanocrystals are capped or coated and the non-polar organic solvent comprises hexane or toluene, or a mixture thereof.

43. The dispersion of claim 40 further comprising a surfactant, a polymer, a liquid crystal forming material, a phospholipid, or a mixture thereof;

and optionally further comprising a matrix precursor.

44. The dispersion of claim 43 wherein the matrix precursor comprises an organic matrix precursor adapted for polymerization for formation of an organic matrix, or an inorganic matrix precursor adapted for formation of an inorganic matrix, or a mixed organic/inorganic matrix precursor adapted for formation of an organic/inorganic matrix, or any mixture thereof.

45. The dispersion of claim 44 wherein the organic matrix comprises a polyacrylate, a poly(methyl methacrylate), a polyurethane, or a block organic copolymer;

or wherein the inorganic matrix comprises silica;

or wherein the organic/inorganic matrix comprises interpenetrating networks of silica and an organic polymer;

or any combination thereof.

46. A method of forming a film comprising a plurality of metal oxide nanocrystals, the method comprising disposing a dispersion of the nanocrystalline form of claim 1 on a substrate, then, removing the liquid substance, to provide the film disposed on the substrate.

47. The method of claim 46 wherein the film further comprises a matrix.

48. The method of claim 46 wherein the substrate comprises an electrically insulating, conductive or semi-conductive material.

49. The method of claim 48 wherein the substrate is a surface composed of a solid material comprising silicon, silicon nitride, silica, diamond, or an organic plastic.

51. A film comprising the nanocrystalline form of claim 1.

52. The film of claim 51 having a thickness of about 10 nm to about 1 millimeter.

53. The film of claim 51 having a dielectric constant of greater than about ten.

54. The film of claim 51 further comprising an organic component used in generation of a mesoporous material.

55. The film of claim 54 wherein the organic compound used in generation of a mesoporous material comprises MCM-41, MCM-48, SBA-15, or SBA-16.

56. The film of claim 51 wherein the film is substantially free of voids or the film is adapted to comprise a particular proportion of voids.

57. The film of claim 51 wherein the film, comprising a type of the nanocrystalline form of claim 1, substantially retains electrical properties, density properties, spectral properties, hardness properties or scratch resistance, or thermal properties, or any combination thereof, of the respective type of nanocrystalline form.

58. A dielectric layer comprising the film of claim 51.

59. A capacitor or an ultracapacitor comprising the dielectric layer of claim 58.

60. The capacitor or ultracapacitor of claim 59 wherein the dielectric layer is disposed on or within a mesoporous structure.

61. A field effect transistor comprising the dielectric layer of claim 58.

62. The field effect transistor of claim 61, comprising:

a semiconductor device, comprising;

a thin film gate dielectric comprising barium titanate nanoparticles of approximately uniform size that is smaller than a domain size associated with ferroelectric hysteresis, wherein a dielectric constant of the dielectric is greater than about 10; and

an organic semiconductor region.

63. The transistor of claim 62, comprising a buffer layer between the dielectric and the organic semiconductor.

64. The transistor of claim 63, wherein the buffer layer comprises parylene C.

65. The transistor of claim 64, wherein the organic semiconductor comprises pentacene.

66. The apparatus of claim 62, wherein the dielectric constant is at least about 40.

67. A display device comprising the dielectric layer of claim 58.

68. A memory device comprising the dielectric layer of claim 58 such that the dielectric layer is disposed as a gate dielectric in a transistor in a memory cell in an array of memory cells of the memory device.

69. A memory device comprising the dielectric layer of claim 58 such that the dielectric layer is disposed as a capacitor dielectric in a capacitor coupled to a transistor in a memory cell in an array of memory cells of the memory device, the capacitor structured in the memory cell as a data storage unit.

70. The memory device of claim 69, wherein the nanocrystals are ferroelectric.

71. The memory device of claim 69, wherein an electrode of the capacitor is disposed as a gate of the transistor.

72. An opto-electronic device comprising the dielectric layer of claim 58.

73. The opto-electronic device of claim 72, wherein the dielectric layer is arranged in a switching element thereof.

74. A coating layer comprising the nanocrystalline form of claim 1.

75. The coating layer of claim 74 comprising zinc oxide, titanium oxide, or zirconium oxide.

76. The coating layer of claim 75 further comprising a cream or oil adapted for application to human skin.

39. The method of claim 118 wherein the nanocrystals comprise decanoic acid capped BaTiO₃ nanocrystals of about 6-10 nm size, or wherein the nanocrystals comprise oleic acid capped BaTiO₃ nanocrystals of about 3-5 nm size, or wherein the nanocrystals comprise oleic acid capped BaTiO₃ nanoparticle/nanorod mixture of about 10-20 nm size, or wherein the nanocrystals comprise oleic acid capped BaTiO₃ nanocrystals of about 2-3 nm size.

50. The method of any 46 wherein the film is substantially free of voids or the film is adapted to comprise a particular proportion of voids.