KR20090040450A - Yag-based ceramic garnet material comprising at least one multi-site element - Google Patents

Abstract

The invention relates to a YAG-based ceramic garnet material comprising at least one multi-site element capable of replacing the Y and/or Al-sites within the YAG-material.

Description

YAV-BASED CERAMIC GARNET MATERIAL COMPRISING AT LEAST ONE MULTI-SITE ELEMENT}

The present invention relates to ceramic garnet materials, and more particularly to these materials used in light emitting devices, in particular LEDs.

Today's light emitting devices, especially LEDs, contain a significant amount of Ce (III) doped YAG based materials due to the excellent material properties of YAG. In this regard, it is mentioned, for example, in US 2003/0078156 A1, incorporated herein by reference.

However, in particular for light emitting devices using Ce (III) doped YAG based materials in ceramic and / or crystalline form, in particular, secondary phases in YAG, in particular YAG (perovskite)- It has been observed that the preparation of these YAG-ceramics is often faced with difficulties because the material composition must be kept precisely so that phases do not exist.

Phase relationships in the alumina-yttria system are known, for example, from J. Bell, IRHarris, B. Cockayne and B. Len, J. Mate. Sci, 9 (1974) 527. In the solid state, Y ₃ Al ₅ O ₁₂ (YAG) is the neighboring phases formed in polycrystalline garnet YAG materials, deviating from the ideal stoichiometry, such as alumina, Al ₂ O ₃ , or YAP, YAlO. ₃ With crystallization as a line compound.

From MMKuklja and R.Pandey, J. Am. Ceram. Soc. 82 (1999) 2881, intrinsic anti-site disorders deviated from the ideal stoichiometry, ie Y ₃ Al ₅ O ₁₂ (YAG) It is known to be a dominant mechanism for controlling the transient amount of Y ₂ O ₃ or Al ₂ O ₃ in garnet compounds. Such anti-site disorders are particularly oxidized, since the inclusion of yttrium at octahedral aluminum sites is strongly more advantageous than the inclusion of aluminum at dodecahedral yttrium sites. Compositions exhibiting yttrium transients can lead to an expansion of the single phase existence area surrounding the non-employed compound stoichiometry.

However, especially in the industrial production of Ce (III) doped YAG-ceramic, it is often impossible to accurately maintain the correct composition due to weighing errors or variations during the manufacturing process.

It is an object of the present invention to provide a YAG based ceramic garnet material having improved properties, which in particular allows greater manufacturing tolerances in various applications.

This object is achieved by a YAG based ceramic garnet material according to claim 1 of the present invention and / or a method according to claim 9 of the present application. Accordingly, a YAG based ceramic garnet material is provided that includes at least one multi-site element that can occupy octahedral and / or dodecahedral coordinating cationic lattice sites within the YAG based ceramic garnet material.

Surprisingly, it has been found that by using such YAG based ceramic garnet materials, manufacturing tolerances can be greatly improved without affecting the properties of YAG based ceramics in most applications in the present invention. In some applications, even the properties of YAG based ceramic garnet materials may be improved. Although not determined by any theory, the inventors have found that the ability of at least one multi-site element to function as a placeholder for other ions, in particular Y and / or Al ions in the YAG material, is due to It is believed to help extend the processing window.

The term " YAG based " particularly means that M ^I is Mg, Ca, Y, Na, Sr, Gd, La, Ce, Pr, Nd, Sm, Eu, Dy, Tb, Ho, Er, Tm, Yb, Lu or The mixture is selected from the group of mixtures, M ^II is selected from the group of Al, Ga, Mg, Zn, Y, Ge, Sc, Zr, Ti, Hf, Lu or mixtures thereof, and M ^III is selected from Al, Si, B, Ge, Ga, V, As, Zn or mixtures thereof, X is selected from the group of O, S, N, F, Cl, Br, I, OH and mixtures thereof and M ^II X ₆ octahedron and M ^III ₃ 4 A substance consisting of tetrahedrons (each octahedron is bonded to the other six through a tetrahedron that shares a vertex) .M ⁱ ₃ M ^II ₂ (M ^III X ₄ ) ₃ Meaning and / or include. Each tetrahedron shares its vertices with four octahedrons, resulting in (M ^II X ₃ ) ₂ (M ^III X ₂ ) ₃ . The larger ions M ^I occupy positions of eight coordination (12-sided) in the interstices of the framework, so that the final composition M ^I ₃ M ^II ₂ M ^III ₃ X ₁₂ or M ^I ₃ M ^II ₂ ( M ^III X ₄ ) ₃ .

The term " main ingredient " particularly refers to at least 95%, preferably at least 97%, most preferably at least 99% (at least one multi-site element and no added dopant material) of the YAG based ceramic garnet material. It is composed of this material.

In some garnet materials in the present invention, it should be noted that the M ^II and M ^III positions are at least partially occupied by atoms of the same element.

It should be noted that the YAG based ceramic material may be doped with a material selected from the group of Lu, Pr, Sm, Tb, Dy, Ho, Er, Tm, Yb, La, Ce or mixtures thereof.

The term "YAG based ceramic garnet material" in the context of the present invention also means and / or comprises a mixture of the material as described above with additives which can be added, in particular during ceramic processing. These additives may be included completely or partly in the final material, which may then also be a composite of several chemically different species, and in particular may comprise such species as known in the art as solvents. Suitable solvents include alkaline earth- or alkaline metal oxides and halides, borates, SiO _2, and the like.

The term "ceramic material" in the sense of the present invention means and / or includes, in particular, a crystalline or polycrystalline compressed material or synthetic material with or without a controlled amount of pores.

In the context of the present invention, the term "polycrystalline material" refers in particular to a material having a volume density of greater than 90% of the main component, consisting of more than 80% of single crystal domains (each domain having a diameter of greater than 0.5 μm). Meanings and / or include and may have different crystallographic orientations. These single crystal domains may be linked by an amorphous or glassy material or by additional crystalline components.

According to a preferred embodiment of the invention, the ion radius for the six fold coordination of at least one multi-site element is greater than or equal to 70 pm and less than or equal to 104 pm and / or the ion radius for the eight-fold configuration of at least one multi-site element. Is 85 pm or more and 116 pm or less. This has been shown to be most effective in many applications within the present invention.

It should be noted that where there are several different multi-site elements, it is particularly preferred that all multi-site elements have the same ion radius as described above, which applies to make the necessary changes to all other embodiments within the invention. .

According to a preferred embodiment of the present invention, the ion radius for the sixfold configuration of the at least one multi-site element is 75 pm or more and 104 pm or less, more preferably 88 pm or more and 102 pm or less.

According to a preferred embodiment of the present invention, the ion radius with respect to the eighth configuration of the at least one multi-site element is 90 pm or more and 114 pm or less, more preferably 92 pm or more and 112 pm or less.

According to one embodiment of the invention, the concentration of the at least one multi-site element is greater than or equal to 0.5 mol% and less than or equal to 5 mol% with respect to the YAG based garnet structure. This has been shown to be the most appropriate range for obtaining the widest treatment window without degrading the properties of YAG materials in various applications within the present invention.

According to one embodiment of the invention, the concentration of at least one multi-site element is 0.1 atom% or more and 0.7 atom% or less, preferably 0.2 atom% or more and 0.4 atom or less, based on the sum of the cations of the formula unit. atom% or less.

According to one embodiment of the invention, the sum of (Y, Lu, Gd, Pr, Sm, Tb, Dy, Ho, Er, Tm, Yb, La, Ce, Ca) and (Al, B) in a ceramic garnet material , Si, Mg, Ge, Zr, Hf, Ga, Sc) is a ratio of 0.590 to 0.610. By doing so, in various applications, the most suitable YAG-ceramic materials can be obtained. Preferably, the sum of (Y, Lu, Gd, Pr, Sm, Tb, Dy, Ho, Er, Tm, Yb, La, Ce, Ca) and (Al, B, Si, Mg, The ratio of sum of Ge, Zr, and Hf) is 0.593 or more and 0.607 or less, More preferably, they are 0.595 or more and 0.605 or less.

According to a preferred embodiment of the present invention, the ratio of the main phase to the possible secondary phase (s) in the YAG based ceramic garnet material is at least 10: 1, preferably at least 20: 1, most preferred More than 40: 1.

In the context of the present invention, the term "secondary phase" means and / or includes minor constituents of the final mixture, in particular exhibiting different chemical compositions and / or crystal structures.

According to a preferred embodiment of the present invention, at least one multi-site element is selected from the group comprising Sc, Ga, Yb, Lu, Mg and mixtures thereof. These materials themselves have proven to be actually used in many applications.

According to a preferred embodiment of the present invention, Ce (III) doped YAG based ceramic garnet material after exposing the ceramic material at 200 ° C. for 1000 hours using an optical power density of 10 W / cm ² and an average photon energy of 2.75 eV. The photothermal stability of is 80% or more and 100% or less.

The term "photothermal stability" in the context of the present invention means and / or includes the maintenance of the luminescence intensity, in particular under the condition of simultaneous application of heat and high intensity excitation, ie 100% photothermal stability means that the material is irradiated it is virtually unaffected by the simultaneous application of irradiation and heating.

According to a preferred embodiment of the present invention, Ce (III) doped YAG based ceramic garnet material after exposing the ceramic material at 200 ° C. for 1000 hours using an optical power density of 10 W / cm ² and an average photon energy of 2.75 eV. The photothermal stability is 82.5% or more and 95% or less, and preferably 85% or more and 97% or less.

According to a preferred embodiment of the invention, the thermal conductivity of the YAG-based ceramic garnet material is 0.07Wcm ^-1 K ^-1 or higher 0.15Wcm ^-1 K ^-1 or less.

According to a preferred embodiment of the present invention, the quantum yield of Ce (III) doped YAG _{[ PS1 ]} based ceramic garnet materials is greater than 90% and less than 99%.

The term "quantum yield" in the sense of the present invention means and / or includes in particular the ratio of the number of photons emitted to the number of photons absorbed.

According to a preferred embodiment of the present invention, the quantum yield of YAG based ceramic garnet materials is at least 93% and at most 99%, preferably at least 95% and at most 98%.

According to one embodiment of the invention, the YAG based ceramic garnet material exhibits a transmission of vertical incidence in air of 10% or more and 85% or less for light in the wavelength range of 550 nm or more and 1000 nm or less.

Preferably, the transmittance to vertical incidence is 20% or more and 80% or less for light in the wavelength range of 550 nm or more and 1000 nm or less in air, and more preferably 30% or more for light in the wavelength range of 550 nm or more and 1000 nm or less. 75% or less, most preferably more than 40% and less than 70%.

In the context of the present invention, the term “transmittance” is especially at least 10%, preferably at least 20%, more preferably at least 30%, most preferably 40% of the incident light at wavelengths that cannot be absorbed by the material. It means that at least 85% transmits the sample (at any angle) with respect to normal incidence in air. It is preferable that this wavelength exists in the range of 550 nm or more and 1000 nm or less.

According to a preferred embodiment of the present invention, the YAG based ceramic garnet material has a density of at least 95% and at most 101% of the theoretical density of the stoichiometric garnet structure.

According to a preferred embodiment of the present invention, the YAG based ceramic garnet material has a density of 97% or more and 100% or less of the theoretical density.

Density of less than 100% according to the above-described preferred embodiment of the present invention is preferably obtained by sintering the ceramic with respect to the stage where there are still holes in the ceramic matrix. Most preferred is a density in the range of 98.0% to 99.8%, which will have a total pore volume in the ceramic matrix in the range of 0.2% to 2%. Preferable average pore diameters are 400 nm or more and 1500 nm or less.

The invention also relates to a method for producing a YAG based ceramic garnet material according to the invention, comprising a sintering step.

The term " sintering step " in the sense of the present invention refers in particular to thermal, which can be combined by application of uniaxial or isostatic pressure, without reaching the liquid state of the main component of the sintered material. It means the step of increasing the density of the precursor powder (precursor powder) under the influence.

According to a preferred embodiment of the present invention, the sintering step is preferably pressureless in a reducing or inert atmosphere.

According to a preferred embodiment of the present invention, the method further comprises pressing the ceramic garnet precursor material to at least 50% and at most 70%, preferably at least 55% and at most 65% of its theoretical density prior to sintering. do. Indeed, this has been shown to improve the sintering steps for most YAG based ceramic garnet materials, as described above in the present invention.

According to a preferred embodiment of the invention, the method for producing a YAG based ceramic garnet material according to the invention follows the following steps:

(a) mixing the precursor material to the YAG based ceramic garnet material,

(b) optionally firing precursor materials at a temperature of preferably at least 1300 ° C. and at most 1700 ° C. to remove volatiles (eg CO ₂ if carbonate is used),

(c) optional grinding and washing steps,

(d) a first pressing step, preferably a uniaxial pressing step using an appropriate powder compression tool having a mold of the desired shape (eg rod-shaped or egg-shaped) and / or preferably 3000 bar or more to 5000 bar. Low temperature isotropic pressing step below,

(e) reducing the inertness at a pressure of 10 ⁻⁷ mbar or more and 10 ⁴ mbar or less or a sintering step of 1500 ° C. or more and 2200 ° C. or less in a slight oxidizing atmosphere,

(f) an optional hot pressing step, preferably a hot isotropic pressing step, preferably at least 30 bar and at most 2500 bar and preferably at a temperature of at least 1500 ° C. and at most 2000 ° C. and / or preferably at least 100 bar at 2500 a high temperature uniaxial pressing step at a temperature of preferably 1500 ° C. or higher and 2000 ° C. or lower, and below bar, and

(g) optional post annealing step above 1000 ° C. and below 1700 ° C. in an inert atmosphere or oxygen containing atmosphere.

According to the method, for the most desired material composition, this manufacturing method produced the best YAG based ceramic garnet materials used in the present invention.

The invention also relates to a light emitting device, in particular an LED, comprising the YAG based ceramic garnet material of the invention.

The YAG based ceramic garnet material according to the present invention, the light emitting device comprising the YAG based ceramic garnet material according to the present invention and / or the YAG based ceramic garnet material produced by the method include a wide range of materials including one or more of the following. It can be used in various systems and / or applications:

Office lighting systems,

Household application systems,

Store lighting systems,

House lighting systems,

Accent lighting systems,

Spot lighting systems,

Theater lighting systems,

Fiber Optic Application Systems

Projection systems,

Self-lit display systems,

Pixelated display systems,

Partitioned display systems,

Warning display systems,

Medical lighting application systems,

Indicator display systems

Decorative lighting systems,

Portable systems,

Automotive applications,

Greenhouse lighting systems,

Window materials and window applications,

Laser application systems, in particular for polycrystalline laser materials with garnet host lattice,

Light-emitting device housings especially for HID lamps, and

Optical lenses or elements with high refractive index.

In addition to the foregoing components, the components to be used and the claimed components to be used in accordance with the invention in the disclosed embodiments have no specific exceptions to their size, shape, material options and technical concepts. As such, the selection criteria known in the art may be applied without limitation.

Further details, features, features and advantages of the object of the invention are set forth in the dependent claims, and the features and the following description (in exemplary form) of the features and examples are in accordance with the invention. Some embodiments and examples of YAG based ceramic garnet materials are shown.

1 illustrates the microstructure of a YAG based ceramic garnet material according to Example I of the present invention.

2 shows a microstructure of a YAG based ceramic garnet material according to Example II of the present invention.

3 shows a microstructure of a YAG based ceramic garnet material according to Example III of the present invention.

4 shows a microstructure of a YAG based ceramic garnet material according to Example IV of the present invention.

5 shows the microstructure of YAG ceramic garnet material according to Comparative Example I;

6 shows the microstructure of YAG ceramic garnet material according to Comparative Example II.

7 shows the microstructure of YAG ceramic garnet material according to Comparative Example III.

8 shows a microstructure of a YAG ceramic garnet material according to Comparative Example IV.

Examples I to IV

The present invention will be better understood from four examples of inventive YAG based ceramic garnet materials, examples I-IV, which are merely exemplary forms.

These garnet materials were made in the following manner:

First, Y ₂ O ₃ (99.99%, Rhodia), Gd ₂ O ₃ (99.99%, Rhodia), Sc ₂ O ₃ (99.9%), Al ₂ O ₃ (99.99%, Baikowski) ) And CeO ₂ (> 99%, Rhodia) were weighed and milled using a high density alumina milling medium in isopropanol with 1000 ppm silica added as hydrolyzed tetraethoxysilane. . Then, the ceramic suspension was sieved to remove coarser particles and dried after addition of a polyvinylbutyral based binder system. The powder mixture was then granulated and ceramic green bodies were formed by cold isostatic pressing. After removing the binder in the air atmosphere, the ceramic green bodies are sintered at a temperature in the range 1600-1750 ° C. in an H ₂ / N ₂ (5% / 95%) atmosphere. After processing, the ceramic parts were post annealed at 1200 ° C.-1400 ° C. in air.

Table 1 shows the material compositions of these four inventive examples I to IV.

Compositions of Examples I to IV Original example Metal rain Relative Density After Sintering (rel.density) I (Y0.9Gd0.1) 2.994 Ce0.006 Al4.96 Sc0.02 100.00% II (Y0.9Gd0.1) 2.994 Ce0.006 Al4.98 Sc0.02 99.89% III (Y0.9Gd0.1) 2.994 Ce0.006 Al5.00 Sc0.02 99.96% IV (Y0.9Gd0.1) 2.994 Ce0.006 Al5.02 Sc0.02 100.00%

The amount of multisite cation Sc was chosen as 0.25% relative to the sum of the cations of the formula unit of the stoichiometric garnet composition.

The term "rel. Density" means that the two most dense ceramics (which have the same density) are arbitrarily set to have a relative density of 100%. It can be seen that all ceramics have essentially the same density.

Comparative Examples I to IV

In addition to the original examples above, four comparative examples were also prepared in the same manner as described above, except that there were no at least one multi-site element (ie no Sc).

Table 2 shows the material composition of the four original examples I to IV.

Composition of Ceramic YAG: Ce Samples Comparative example Metal rain Relative Density After Sintering I (Y0.9Gd0.1) 2.994 Ce0.006 Al4.96 100.00% II (Y0.9Gd0.1) 2.994 Ce0.006 Al4.98 98.92% III (Y0.9Gd0.1) 2.994 Ce0.006 Al5.00 99.94% IV (Y0.9Gd0.1) 2.994 Ce0.006 Al5.02 99.55%

 The term "relative density" here also means that the densest ceramic has been arbitrarily set to have a relative density of 100%. The variation in density is slightly larger than in Table 1, where it can be seen that large scattering can be observed in optical properties, for example scattering.

1 to 8 show the microstructures (SEM micrographs) of the inventive examples I to IV (FIGS. 1 to 4, respectively) and Comparative Examples I to IV (FIGS. 5 to 8, respectively).

All original examples show a uniform structure in which no secondary phase is observed, while in all comparative examples it can be seen that there are secondary phases.

In short, it should be noted that the best comparative example is Example II, although the Al component was slightly lower in the initial material mixture. By milling with alumina, fine polishing occurs, and the Al component slightly increases.

Examples III and IV show both alumina secondary phase grains (shown as black grains on a scanning electron microscope) that serve as scattering centers of the ceramic.

However, it is evident that Comparative Example II is the lowest dense ceramic due to the remaining porosity. In various applications, since there is a high likelihood that there will be no eutectic secondary phase functioning as a sintering aid, it has been observed that without at least one multi-site element, materials with the correct composition are often the strongest difficult materials to sinter. If at least one multi site element is added, this can be overcome; All original examples showed good sintering properties.

Certain combinations of elements and features in the foregoing detailed embodiments are merely illustrative; It is also contemplated that these disclosures be interchanged with and replaced with other disclosures within the patents / applications incorporated herein by reference. As will be appreciated by one of ordinary skill in the art, variations, modifications, and other implementations of what is disclosed herein are conventional in the art without departing from the spirit and scope of the claimed invention. Can be done by anyone with knowledge of Accordingly, the foregoing description is for illustrative purposes only and is not intended to be limiting. The scope of the invention is defined in the following claims and their equivalents. Also, reference signs used in the description and the claims do not limit the scope of the invention as claimed.

Claims (10)

YAG-based ceramic garnet material, wherein at least one multi-site element that can occupy octahedral and / or dodecahedral sites within the YAG-based ceramic garnet material YAG based ceramic garnet material comprising a site element. The method of claim 1, YAG-based ceramic garnet material, wherein the ion radius of the at least one multi-site element on a six fold coordinated cation lattice site included in a Ce (III) doped YAG based ceramic garnet material is 70 pm to 104 pm. . The method according to claim 1 or 2, Wherein the concentration of the at least one multi-site element is at least 0.1 atom% and not more than 0.7 atom% of the sum of the cations of the garnet structure. The method according to any one of claims 1 to 3, Sum of (Y, Lu, Gd, Pr, Sm, Tb, Dy, Ho, Er, Tm, Yb, La, Ce, Ca) in the ceramic garnet material and (Sc, Ga, Al, B, Mg, A YAG-based ceramic garnet material, wherein the ratio of the sum of Si, Ge, Zr, Hf) is 0.590 to 0.610. The method according to any one of claims 1 to 4, And wherein the ratio of the main phase to possible secondary phase (s) in the YAG based ceramic garnet material is at least 10: 1. The method according to any one of claims 1 to 5, The at least one multi-site element is selected from the group comprising Sc, Ga, Yb, Lu, Mg and mixtures thereof. The method according to any one of claims 1 to 6, The photothermal stability of the YAG based ceramic garnet material after exposure of the ceramic material at 200 ° C. for 1000 hours using an optical power density of 10 W / cm ² and an average photon energy of 2.75 eV is greater than 80% and 100% YAG based ceramic garnet materials, hereinafter. 8. A light emitting device, in particular an LED, comprising the YAG based ceramic garnet material of claim 1. A method of producing a YAG based ceramic garnet material for a light emitting device according to any one of claims 1 to 7, comprising a sintering step. A system comprising a YAG based ceramic garnet material according to claim 1, a light emitting device according to claim 8 and / or a YAG based ceramic garnet material produced according to the method of claim 9. silver, Office lighting systems, Household application systems, Store lighting systems, House lighting systems, Accent lighting systems, Spot lighting systems, Theater lighting systems, Fiber optic application systems Projection systems, Self-lit display systems, Pixelated display systems, Compartmentalized display systems, Warning display systems, Medical lighting application systems, Indicator display systems Decorative lighting systems, Portable systems, Automotive applications, Greenhouse lighting systems, Window materials and window applications, Laser application systems, in particular for polycrystalline laser materials having a garnet host lattice, Light emitting device housings especially for HID lamps, and Optical lenses or elements with high refractive index A system used in one or more of the applications.

Images