Rare earth oxide nanocrystals and methods of forming

• US 20080175779A1
• Filed: 03/30/2005
• Published: 07/24/2008
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Cao, Yunwei Charles
• Granted Patent: US 7,527,773 B2
• Time in Patent Office: Days
• US Class Current: 423/263
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01F 17/218 Yttrium oxides or hydroxides
• CPC Class Codes: C01F 17/224 Oxides or hydroxides of lanthanides
• CPC Class Codes: C01F 17/229 Lanthanum oxides or hydroxides
• CPC Class Codes: C01F 17/235 Cerium oxides or hydroxides
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/52 highly monodisperse size distribution
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C30B 7/00 Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions from molten solvents C30B9/00; by normal or gradient freezing C30B11/00; under a protective fluid C30B27/00
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

A method of forming rare earth oxide nanocrystals include the steps of dissolving a rare earth including compound in a solution containing at least one organic solvent, heating the solution to a temperature of at least 160° C., wherein a concentration of the rare earth including compound provided upon decomposition is sufficient to provide critical supersaturation of at least one active intermediate in the solution to nucleate a plurality of rare earth oxide nanocrystals. The plurality of rare earth nanocrystals are then grown, wherein the growing step proceeds at least in part in the absence of critical supersaturation of the active intermediate. The rare earth nanocrystals can assemble into at least one close-packed, ordered nanocrystal superlattice.

Claims

1. A method of forming rare earth oxide nanocrystals, comprising the steps of:

dissolving a rare earth comprising compound in a solution containing at least one organic solvent;

heating said solution to a temperature of at least 160°

C., wherein a concentration of said rare earth comprising compound provided upon decomposition is sufficient to provide critical supersaturation of at least one active intermediate in said solution and nucleate a plurality of rare earth oxide nanocrystals,

growing said plurality of rare earth nanocrystals, said growing step proceeding at least in part in the absence of said critical supersaturation of said active intermediate, and

separating said plurality of rare earth nanocrystals from said solution.

2. The method of claim 1, wherein said organic solvent includes at least one coordinating solvent.

3. The method of claim 2, wherein said coordinating solvent comprises oleic acid.

4. The method of claim 1, wherein said organic solvent includes at least one non-coordinating solvent.

5. The method of claim 4, wherein said non-coordinating solvent comprises octadecene.

6. The method of claim 1, wherein said organic solvent comprises at least one coordinating solvent and at least one non-coordinating solvent.

7. The method of claim 1, wherein said dissolving step is performed at a temperature of less than 100°

C.

8. The method of claim 1, wherein following said dissolving step, no further rare earth comprising compound is added to said solution.

9. The method of claim 1, wherein said heating step is performed at a temperature of at least 300°

C.

10. The method of claim 1, wherein all respective dimensions of said plurality of rare earth nanocrystals are within a standard deviation of less than 10%.

11. The method of claim 1, wherein said plurality of rare earth nanocrystals are monodisperse.

12. The method of claim 1, wherein a thickness of said plurality of rare earth nanocrystals is no more than two times a unit cell size of said plurality of rare earth nanocrystals.

13. The method of claim 1, wherein said rare earth comprises gadolinium and said plurality of rare earth nanocrystals comprise Gd₂O₃.

14. The method of claim 1, wherein said plurality of rare earth nanocrystals are square shaped (nanoplates).

15. The method of claim 1, wherein said plurality of rare earth nanocrystals are triangularly shaped.

16. The method of claim 1, wherein said dissolving step is performed under vacuum.

17. The method of claim 1, further comprising the step of solvent removal, wherein said plurality of rare earth nanocrystals self-assemble into at least one close-packed, ordered nanocrystal superlattice.

18. A composition of matter, comprising:

a plurality of rare earth oxide nanocrystals, wherein all respective dimensions of said plurality of rare earth nanocrystals are within a standard deviation of less than 10%.

19. The composition of claim 18, wherein a thickness of said plurality of rare earth nanocrystals is no more than two times a unit cell size of said plurality of rare earth nanocrystals.

20. The composition of claim 18, wherein said plurality of rare earth nanocrystals have an average area of less than 100 nm, and an average thickness of no more than no more than two times a unit cell size of said plurality of rare earth nanocrystals.

21. The composition of claim 18, wherein said plurality of rare earth nanocrystals are monodisperse.

22. The composition of claim 18, wherein said plurality of rare earth nanocrystals are assembled into at least one close-packed, ordered nanocrystal superlattice.