PHOSPHOR IN POLYCRYSTALLINE CERAMIC STRUCTURE AND A LIGHT-EMITTING ELEMENT COMPRISNG SAME

• US 20110181173A1
• Filed: 12/17/2010
• Published: 07/28/2011
• Est. Priority Date: 03/14/2005
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.), Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: DE GRAAF, JAN, KOP, THEO ARNOLD
• Granted Patent: US 8,496,852 B2
• Time in Patent Office: Days
• US Class Current: 313/483
• CPC Class Codes: C04B 2111/807 Luminescent or fluorescent materials
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• 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 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/6022 Injection moulding
• CPC Class Codes: C04B 2235/6023 Gel casting
• CPC Class Codes: C04B 2235/6027 Slip casting
• CPC Class Codes: C04B 2235/785 Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/786 Micrometer sized grains, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 35/44 based on aluminates
• CPC Class Codes: C04B 35/6261 Milling
• CPC Class Codes: C04B 35/62625 Wet mixtures
• CPC Class Codes: C04B 35/63 using additives specially adapted for forming the products , e.g.. binder binders
• CPC Class Codes: C04B 35/632 Organic additives
• CPC Class Codes: C04B 35/6455 Hot isostatic pressing
• CPC Class Codes: C04B 38/0054 the pores being microsized or nanosized
• CPC Class Codes: C09K 11/7774 : Aluminates
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension

Abstract

The invention relates to a phosphor in a polycrystalline ceramic structure and a light-emitting element provided with the same comprising a Light-Emitting Diode (LED) in which a composite structure of phosphor particles is embedded in a matrix, characterized in that the matrix is a ceramic composite structure comprising a polycrystalline ceramic alumina material, hereafter called luminescent ceramic matrix composite. This luminescent ceramic matrix composite can be made by the steps of converting a powder mixture of ceramic phosphor particles and alumina particles into a slurry, shaping the slurry into a compact, and applying a thermal treatment, optionally in combination with hot isostatic pressing into a polycrystalline phosphor-containing ceramic alumina composite structure. The luminescent ceramic matrix composite further allows a method of tuning the light-diffusing properties by changing at least one of the fractions of phosphor particles and second ceramic particles, the grain size of the particles of the ceramic composite structure, the difference in the refractive index of the particles of the ceramic composite structure, and the porosity in the polycrystalline phosphor-containing ceramic composite structure.

Claims

1-14. -14. (canceled)

15. A light-emitting element comprising a light-emitting diode (LED) and a phosphor in a polycrystalline ceramic structure comprising a phosphor of the doped YAG type, characterized in that the phosphor is embedded in a ceramic matrix comprising non-luminescent polycrystalline alumina, wherein the ceramic matrix comprises 80 to 99.99 vol. % alumina and 0.01 to 20 vol. % phosphor.

16. The light-emitting element according to claim 15, wherein the luminescent ceramic matrix composite is applied as a plate on top of or as a shaped cup over the LED and has a thickness between about 50 μ

m and about 1 mm.

17. A light-emitting device comprising the element of claim 15.

18. A method of making a phosphor in a polycrystalline ceramic structure comprising a phosphor of the doped YAG type, characterized in that the phosphor is embedded in a ceramic matrix comprising non-luminescent polycrystalline alumina, wherein the ceramic matrix comprises 80 to 99.99 vol. % alumina and 0.01 to 20 vol. % phosphor, comprising the steps of converting a powder of phosphor and alumina particles into a slurry, shaping the slurry into a polycrystalline phosphor-containing ceramic alumina composite structure, and applying a thermal treatment, optionally in combination with hot isostatic pressing into the ceramic matrix, after which the ceramic matrix is mounted to a LED.

19. The method according to claim 18, wherein the slurry is shaped into a polycrystalline phosphor-containing ceramic matrix by means of slip casting or injection molding so as to obtain a ceramic light-converting package, a collimating lens or collimating reflector, a coupling-out structure for light, or a heat-dissipating device.

20. A method of tuning light-diffusing properties of the phosphor in a polycrystalline ceramic structure of comprising a phosphor of the doped YAG type, characterized in that the phosphor is embedded in a ceramic matrix comprising non-luminescent polycrystalline alumina, wherein the ceramic matrix comprises 80 to 99.99 vol. % alumina and 0.01 to 20 vol. % phosphor by changing a parameter of the phosphor in a polycrystalline ceramic structure.

21. The method of claim 20 wherein the parameter changed is the fractions of phosphor and alumina in the ceramic matrix.

22. The method of claim 20 wherein the parameter changed is the fractions of phosphor and alumina in the ceramic matrix. the average particle size of the particles comprised in the ceramic matrix.

23. The method of claim 20 wherein the parameter changed is the porosity of the ceramic matrix.

24. A method of tuning light-emission properties of the phosphor in a polycrystalline ceramic structure of comprising a phosphor of the doped YAG type, characterized in that the phosphor is embedded in a ceramic matrix comprising non-luminescent polycrystalline alumina, wherein the ceramic matrix comprises 80 to 99.99 vol. % alumina and 0.01 to 20 vol. % by changing a parameter of the phosphor in a polycrystalline ceramic structure.

25. The method of claim 24 wherein the parameter changed is the fractions of phosphor and alumina in the ceramic matrix.

26. The method of claim 24 wherein the parameter changed is the ratio of Ce and/or Pr to YAG in the phosphor.

27. The method of claim 24 wherein the parameter changed is the composition of the YAG.