Method for producing sphere-based crystals

• US 20040262790A1
• Filed: 05/04/2004
• Published: 12/30/2004
• Est. Priority Date: 06/15/2000
• Status: Active Grant

• Current Assignee: Diane Lewis, Guoyi Fu
• Original Assignee: Diane Lewis, Guoyi Fu
• Inventors: Lewis, Diane, Fu, Guoyi
• Granted Patent: US 7,025,909 B2
• Time in Patent Office: Days
• US Class Current: 264/1.21
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: C04B 14/062 Microsilica, e.g. colloïdal silica preparing microsilica slurries or suspensions C04B18/148
• CPC Class Codes: C04B 32/00 Artificial stone not provided for in other groups of this subclass
• CPC Class Codes: C04B 35/14 based on silica
• CPC Class Codes: C04B 38/0615 the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles C04B38/0022 takes precedence
• CPC Class Codes: C04B 40/006 involving the elimination of excess water from the mixture
• CPC Class Codes: C30B 29/60 characterised by shape
• CPC Class Codes: C30B 5/00 Single-crystal growth from gels under a protective fluid C30B27/00
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices

Abstract

A moving bed filtration process for the production of sphere based crystals is disclosed. Sphere based crystals having an opal-like structure or an inverse opal-like structure can be produced in accordance with the invention.

Claims

1. :

A process for the production of homogeneously packed opal-like or inverse opal-like sphere-based crystals comprising;

(a) adding a sufficient amount of a suspension of monospheres having a particle size of 20 nanometers to 30 microns to a flat moving bed porous filtration membrane so as to form a layer thickness on the flat moving bed of 50 microns to 5 mm;

(b) moving the monospheres on the moving bed filtration membrane substantially horizontally over a vacuum filtration zone, and applying a sufficient substantially constant vacuum filtration pressure to the monospheres to obtain crystalline homogeneously packed monospheres;

(c) processing the packed monospheres for stabilization, said processing comprising heating and/or chemically bonding the crystalline packed monospheres.

2. :

A process according to claim 1, wherein processing of the packed monospheres for stabilization comprises infiltrating the packed monospheres with a chemical bonding agent.

3. :

A process according to claim 2, wherein the infiltrating step is accomplished while the packed monospheres are moving on the vacuum bed filtration membrane and while a vacuum filtration pressure is being applied to the packed monospheres.

4. :

A process according to claim 2, further comprising curing the chemical bonding agent.

5. :

A process according to claim 1, wherein the monospheres comprise SiO₂.

6. :

A process according to claim 1, wherein the monospheres comprise a polymeric material.

7. :

A process according to claim 1, for the production of inverse opal-like sphere based crystals wherein

in step (c) the packed monospheres are processed for stabilization by infiltrating the packed monospheres with a bonding agent; and

further comprising

(d) removing the monospheric material to obtain an inverse opal-like structure comprising air-spheres.

8. :

A method according to claim 7, wherein the infiltrating step is accomplished while the packed monospheres are moving on the vacuum bed filtration membrane and while a vacuum filtration pressure is being applied to the packed monospheres.

9. :

A process according to claim 7, wherein the bonding agent comprises SiO₂, Al₂O₃, TiO₂, SnO₂, Fe₂O₃, ZrO₂, CeO₂ or Y₂O₃.

10. :

A process according to claim 6, wherein the polymeric material comprises polystyrene, polymethacrylate, or polyvinyltoluene.

11. :

A process according to claim 1, wherein the suspension has a concentration of monospheres of 2-50% by weight of solids.

12. :

A process according to claim 11, wherein the concentration is 10% to 20% by weight.

13. :

A process according to claim 1, wherein the vacuum pressure is about 400 to about 600 mm Hg.

14. :

A process according to claim 11, wherein the vacuum pressure is about 400 to about 600 mm Hg.

15. :

A process according to claim 12, wherein the vacuum pressure is about 400 to about 600 mm Hg.

16. :

A process according to claim 1, wherein the monospheres have a particle size in the range of 100 nanometers to 10 microns.

17. :

A process according to claim 14, wherein the monospheres have a particle size in the range of 150-450 nanometers.

18. :

A process according to claim 1, wherein the monospheres are deposited in a layer thickness of about 200 microns to 1 millimeter.

19. :

A process according to claim 16, wherein monospheres are deposited in a layer thickness of about 200 microns to 1 millimeter.

20. :

A process according to claim 17, wherein monospheres are deposited in a layer thickness of about 200 microns to 1 millimeter.

21. :

A process according to claim 1, wherein the pores of the porous filtration membrane is equal to or slightly smaller than the spheres to be filtered.