Alumina-based photoconversion member composition and ceramic phosphor plate using same

Abstract

Disclosed are: a composition for a ceramic phosphor plate in which alumina is used as a photoconversion member for LEDs and LDs; and a ceramic phosphor plate manufactured using same. According to an aspect of the present invention, provided is an alumina-based composition for a photoconversion member, the composition comprising: polycrystalline alumina (Al2O3) as a ceramic matrix material; a phosphor that performs a photoconversion function; a stabilizer; and a sintering aid.

Description

Alumina-based photoconversion member composition and ceramic fluorescent plate using the same

[0001] The present invention relates to a composition for a ceramic phosphor plate using alumina for use as a light conversion member for LEDs and LDs, and to a ceramic phosphor plate manufactured using the same.

[0002] The content described in this section merely provides background information for the present embodiment and does not constitute prior art.

[0003] High-power blue LEDs and laser diodes (LDs), which are attracting attention as next-generation solid-state lighting technologies, are key elements for achieving high-brightness white light. White light is produced by combining blue light emitted from the LED or LD with yellow light, a portion of which is converted to yellow, and then mixed with colored light. A phosphor layer is used as a light-conversion element to convert some of the blue light to yellow.

[0004] In the past, white LEDs were implemented by dispersing fluorescent substances as particles in a resin and applying them to blue LED elements. However, this structure had problems such as color shift due to deterioration of the resin during long-term use, and defects occurring due to low thermal conductivity and uneven mixing of fluorescent substance powder, which lowered the reliability and stability of the elements.

[0005] Accordingly, transparent fluorescent plates using ceramic sintered bodies as a phosphor matrix are being applied, attempting to reduce luminescence loss and minimize degradation compared to conventional technologies using resin as a matrix. In particular, plates in which phosphors are dispersed in a glass composition as a matrix are most commonly applied. Glass compositions have high transparency, excellent light transmittance, and are relatively resistant to damage from light or heat, thus possessing properties that are highly advantageous for ensuring long-term reliability and enhancing the luminous efficiency of LED elements.

[0006] Meanwhile, with the increasing use of high-power LEDs, the thermal stability of ceramic fluorescent plates is considered a critical performance indicator, making high heat dissipation performance of ceramic plates essential. However, glass does not offer excellent thermal conductivity, and its coefficient of thermal expansion may differ from that of the LED chip or other components. This can lead to cracking or delamination due to thermal stress. Furthermore, pores formed within the matrix can reduce luminous efficiency.

[0007] Accordingly, attempts are being made to improve the thermal stability of LED devices by using alumina, which has high thermal conductivity and coefficient of thermal expansion, as a matrix material. However, alumina also presents problems in that pores or oxygen vacancies can form during the sintering process. Therefore, there is a need to develop a ceramic plate for use as a light conversion element that secures luminous efficiency while also improving thermal stability and mechanical strength.

[0008] One embodiment of the present invention aims to provide a composition for a light conversion member that can be sufficiently applied to high-power LEDs and LDs by applying alumina, a ceramic material having excellent thermal conductivity, as a matrix of a ceramic phosphor plate, thereby improving optical and thermal characteristics generated in an LED compared to a light conversion member using a conventional resin binder or glass-based ceramic material as a matrix.

[0009] According to one aspect of the present invention, a composition for a light conversion member is provided, which comprises alumina-based light conversion member composition comprising polycrystalline alumina (Al2O3), which is a ceramic matrix material, a fluorescent substance performing a light conversion function, a stabilizer, and a sintering agent.

[0010] According to one aspect of the present invention, the sintering agent is characterized in that it includes at least one selected from alkaline earth metal halides, aluminum halides, zinc halides, and halides of rare earth elements.

[0011] According to one aspect of the present invention, the polycrystalline alumina is characterized by having a purity of 99.5% or more and an average particle size in the range of 0.05 to 1 μm.

[0012] According to one aspect of the present invention, the phosphor is characterized by being at least one selected from the group consisting of garnet-based phosphors including yttrium aluminum garnet (YAG) series, lutetium aluminum garnet (LuAG) series, nitride-based phosphors, sulfide-based phosphors, silicate-based phosphors, and mixtures thereof.

[0013] According to one aspect of the present invention, the phosphor is characterized by having an excitation band at a wavelength of 400 to 500 nm and an emission peak at a wavelength of 500 to 700 nm, and including a doped YAG type phosphor.

[0014] According to one aspect of the present invention, the stabilizer is characterized in that it is at least one selected from zinc peroxide (ZnO2), zirconium oxide (ZrO2), cerium(III) oxide (Ce2O3), cerium(IV) oxide (CeO2), titanium dioxide (TiO2), and manganese oxide (MnO2).

[0015] According to one aspect of the present invention, the stabilizer is characterized in that it is included in an amount of 0.01 to 0.5 wt% relative to the composition for the photoconversion member.

[0016] According to one aspect of the present invention, the fluorescent substance is characterized in that it is included in an amount of 1 to 39 wt% relative to the composition for the photoconversion member.

[0017] According to one aspect of the present invention, the sintering agent is characterized in that it is included in an amount of 0.1 to 3 wt% relative to the composition for the photoconversion member.

[0018] According to one aspect of the present invention, a ceramic phosphor plate characterized in that it is manufactured from the composition for the above-described photoconversion member is provided.

[0019] According to one aspect of the present invention, the ceramic fluorescent plate is characterized in that it has a porosity of 1% or less.

[0020] As described above, according to one aspect of the present invention, the composition for a light conversion member can form a ceramic phosphor plate that is advantageous for heat dissipation by applying alumina as a matrix, thereby having the advantage of obtaining a higher luminous flux under the same power conditions.

[0021] In addition, by further including a stabilizer for optimizing the ceramic matrix structure in the composition, the sintering of alumina can be promoted while simultaneously controlling structural defects that may occur during the sintering process, thereby further improving luminous efficiency.

[0022] FIG. 1 is a cross-sectional view illustrating a ceramic phosphor plate manufactured using a photoconversion member composition according to one embodiment of the present invention.

[0023] FIG. 2 is a flowchart illustrating a method for manufacturing a ceramic phosphor plate using a photoconversion member composition according to one embodiment of the present invention.

[0024] FIG. 3 shows the results of measuring the spectral distribution of a fluorescent plate according to the type and content of a stabilizer in a photoconversion member composition according to one embodiment of the present invention.

[0025] Figure 4 is a result of comparing the light transmittance of a fluorescent plate according to the content of a stabilizer in a photoconversion member composition according to one embodiment of the present invention.

[0026] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0027] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0028] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0029] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "comprise" or "have" in this application do not preclude the presence or possibility of addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification.

[0030] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0031] Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0032] In addition, each configuration, process, procedure or method included in each embodiment of the present invention may be shared within a scope that is not technically inconsistent with each other.

[0033] FIG. 1 is a cross-sectional view illustrating a ceramic phosphor plate manufactured using a photoconversion member composition according to one embodiment of the present invention.

[0034] Referring to FIG. 1, the ceramic phosphor plate (100) includes alumina (101) as a matrix material, and at least one phosphor (103) and a stabilizer (105) are distributed inside the matrix in the form of particles.

[0035] The ceramic phosphor plate (100) is formed in a plate shape, and the phosphor (103) is contained within the matrix of the ceramic plate (100). For example, when the phosphor (103) is a yellow phosphor, the ceramic phosphor plate (100) can perform a light conversion function that can convert blue light into yellow light.

[0036] Accordingly, the ceramic fluorescent plate (100) can be combined with an LED or LD element that emits blue light, converting a portion of the blue light and transmitting the remaining portion, thereby generating white light by mixing the colored lights.

[0037] A ceramic fluorescent plate (100) is manufactured from a photoconversion member composition according to one embodiment of the present invention through a manufacturing process described below.

[0038] The photoconversion member composition for a ceramic phosphor plate (100) according to the present invention includes alumina, i.e., aluminum oxide (Al2O3), phosphor, a stabilizer, and a sintering aid.

[0039] Alumina, i.e. aluminum oxide (Al2O3), is the basic material forming the matrix of the ceramic phosphor plate (100).

[0040] Alumina boasts excellent hardness, strength, and chemical stability, as well as high electrical insulation and thermal conductivity, making it a versatile material. Therefore, replacing the resins used as matrix materials in conventional light-conversion components with alumina can effectively address the issues of resin deterioration and color purity degradation caused by heat generation from LED elements.

[0041] Additionally, alumina has a higher thermal conductivity than glass-based ceramic materials. Therefore, it can be used to form ceramic phosphor plates that efficiently dissipate heat, resulting in higher luminous flux under the same power conditions.

[0042] It is preferable to use polycrystalline alumina as the alumina applied to the photoconversion member composition of the present invention. Alumina may be α-alumina with a hexagonal crystal system, γ-alumina with a cubic crystal system, etc., and is not particularly limited, but the most common α-alumina with a hexagonal crystal system can be applied.

[0043] According to the structural characteristics of hexagonal alumina based on the difference in crystal structure and refractive index, when alumina is applied as a matrix of a ceramic phosphor plate, reflection or backscattering can be reduced, thereby improving the color homogeneity of the light-emitting element.

[0044] For this purpose, the alumina applied as the matrix material has a purity of at least 99.5% and may be powdered alumina having an average particle size within the range of 0.05 to 50 ㎛. More preferably, the application of fine powdered alumina having an average particle size of 1 ㎛ or less is advantageous in forming a dense ceramic plate structure during the sintering process.

[0045] When using alumina particles with a small particle size, the gaps between particles inside the molded body can be effectively filled during the compression molding process described later, thereby preventing the formation of voids inside the molded body. As a result, the structure of the molded body can be formed more densely during the subsequent sintering process, which can contribute to improving the transparency of the plate.

[0046] Alumina included in the photoconversion member composition may be included in a range of 60 to 98 wt% based on the total weight of the composition, and more preferably, may be included in a range of 76 to 95 wt%.

[0047] The fluorescent substance (103) of the present invention may include at least one type of fluorescent substance. Here, the fluorescent substance refers to a substance that exhibits fluorescence when irradiated with light, radiation, or the like.

[0048] The phosphor performs a light conversion function, and may be one of yellow, green, or red phosphors depending on the required optical characteristics, the color of the lighting, or the application field, and two or more phosphors that emit light of different wavelengths may be combined and used as needed, that is, a single phosphor or a phosphor mixed with two or more types may be used.

[0049] In addition, garnet-based, nitride-based, sulfide-based, or silicate-based phosphors, including yttrium aluminum garnet (YAG) series and lutetium aluminum garnet (LuAG) series, can be applied as phosphors.

[0050] For example, the phosphor included in the photoconversion member composition of the present invention may be a yellow phosphor capable of converting blue light into yellow light. The yellow phosphor may be used without particular limitation as long as it can convert blue light into yellow light, but it is preferable that it has an excitation band in the range of wavelengths 400 to 500 nm and an emission peak in the range of wavelengths 500 to 700 nm. In particular, as a phosphor excited by blue light having a wavelength of 440 to 480 nm, YAG, Ce 3+ Activated YAG (YAG:Ce) 3+ ) or (LuY)3Al5O 12 :Ce 3+ Particles can be applied.

[0051] When applied to white LED, YAG:Ce 3+ Phosphor particles may experience a decrease in conversion efficiency as the LED operating temperature increases. Therefore, by applying alumina, which has superior thermal conductivity to YAG phosphor particles, as a matrix material, the problem of decreased conversion efficiency due to temperature increase can be improved. Furthermore, (LuY)3Al5O2 as a phosphor 12 :Ce 3+ When applying phosphor particles, YAG:Ce 3+Compared to fluorescent particles, it can maintain relatively high conversion efficiency even at high temperatures.

[0052] Phosphor particles having a purity of 99.0% or higher and an average particle diameter of 5 μm to 50 μm can be used. If the size of the phosphor particles becomes excessively large, the dispersibility within the ceramic plate after sintering may deteriorate, which may reduce the light conversion efficiency. Therefore, it is preferable that the average diameter of the phosphor particles does not exceed 50 μm, and it is more advantageous to apply phosphor particles having an average diameter in the range of 10 μm to 30 μm.

[0053] The phosphor included in the photoconversion member composition may be included in a range of 1 to 18 wt% based on the total weight of the composition, and more specifically, it is preferably included in a range of 4 to 9 wt%. However, the content of the phosphor may be partially changed depending on the transmittance and color difference of the ceramic plate formed after the sintering treatment. If the content of the phosphor is excessively high, the transmittance of the ceramic plate may decrease, and yellow light may be excessive, making it difficult to implement white light of the target quality. On the other hand, if the content of the phosphor is less than 1 wt%, blue light is not sufficiently converted, making it difficult to implement white light of the target quality.

[0054] The photoconversion member composition of the present invention may further include a stabilizer.

[0055] The stabilizer can play a role in controlling changes in optical and mechanical properties caused by the structural characteristics of a ceramic plate using alumina as a matrix.

[0056] More specifically, the stabilizer according to the present invention can control the generation of excessive oxygen vacancies during the sintering process of alumina.

[0057] Typically, ceramic materials increase in density and strengthen their bonding strength when sintered at high temperatures. Depending on the oxygen atmosphere within the sintering system, oxygen can enter the ceramic structure, affecting the physical and chemical properties of the ceramic, particularly its microstructure.

[0058] For example, during the high-temperature sintering process of alumina, or aluminum oxide (Al2O3), some oxygen atoms may be released from the lattice in the form of oxygen gas (O2). In particular, in a sintering environment with a low oxygen partial pressure, the release of oxygen gas can more easily create oxygen vacancies.

[0059] Although these oxygen vacancies are considered defects, they can promote ion diffusion during the sintering process, accelerating sintering and increasing density. However, excessive oxygen vacancies can form pores within the ceramic structure, reducing mechanical strength and altering optical properties.

[0060] Ceramic phosphor plates, when there are many pores within the plate, are prone to multiple scattering within the plate, resulting in a decrease in the amount of light passing through the plate, which in turn reduces luminous efficiency and may also reduce light conversion efficiency. Therefore, it is very important to control the porosity and pore size within the ceramic matrix.

[0061] Accordingly, the porosity of the ceramic phosphor plate formed by the light conversion composition of the present invention is preferably 5% or less, and more preferably 1% or less.

[0062] For such porosity control, the composition of the present invention may further include a stabilizer. The stabilizer is a material having high redox activity, and examples thereof include zinc peroxide (ZnO2), zirconium oxide (ZrO2), cerium(III) oxide (Ce2O3), cerium(IV) oxide (CeO2), titanium dioxide (TiO2), and manganese oxide (MnO2). The stabilizer may be applied by selecting one of the exemplified materials or by combining two or more thereof.

[0063] The stabilizer is not limited as long as it is a material with high oxygen ion conductivity during a high-temperature heat treatment process, or a material with high redox activity and oxygen storage capacity and low reactivity with the matrix material.

[0064] The stabilizer is in powder form and is advantageously configured to have a particle size smaller than that of the alumina and phosphor constituting the matrix. More specifically, it is more preferable that the average particle size of the stabilizer of the present invention be in the range of 0.1 to 3 μm.

[0065] The stabilizer may be included in an amount of 0.01 wt% or more and 1 wt% or less based on the total weight of the photoconversion member composition, and more preferably, it is included in a range of 0.01 to 0.5 wt%, which is advantageous in improving the transmittance and luminous efficiency of the ceramic phosphor plate.

[0066] The photoconversion member composition of the present invention may include a sintering agent for the purpose of a flux effect.

[0067] Sintering aids can promote good crystal formation during the sintering process of ceramics, increase the sintering speed by lowering the activation energy of the sintering process, and also control grain growth to obtain a fine crystal structure.

[0068] Accordingly, the sintering agent used in the present invention can be applied without particular limitation as long as it is a material having a flux effect, but it is specifically preferable to use a halide, and it is particularly advantageous to apply fluoride and chloride among the halides.

[0069] For example, the sintering aid included in the photoconversion member composition of the present invention may include alkaline earth metal halides such as CaCl2, BaCl2, SrCl2, CaF2, BaF2, SrF2, MgCl2, MgF2, aluminum halides such as AlF3, zinc halides such as ZnCl2, ZnF-, rare earth element halides such as LaF3, LaCl3, GdF3, GdCl3, LuF3, LuCl3, YF3, YCl3, ScF3, ScCl3, etc., and the sintering aid may be used as one selected from these or as a mixture of two or more thereof.

[0070] The content of the sintering aid may vary depending on the type of matrix material or fluorescent material included in the composition, and may also vary depending on the type of material selected as the sintering aid. However, the sintering aid may be included within a range of 0.1 to 3 wt% based on the total weight of the photoconversion material composition, and more preferably within a range of 0.3 to 1 wt%.

[0071] If the content of the sintering aid is too low, a sufficient flux effect may not be achieved, and conversely, if too much sintering aid is used, the sintering aid may be incorporated into the parent crystal, causing a change in the luminescence color or a decrease in brightness.

[0072] Below, a method for manufacturing a ceramic phosphor plate using the above photoconversion member composition is described.

[0073] FIG. 2 is a drawing illustrating a method for manufacturing a ceramic phosphor plate using a photoconversion member composition according to one embodiment of the present invention.

[0074] Raw materials including alumina, fluorescent substance, stabilizer and sintering agent are mixed in a preset ratio (S210).

[0075] As described above, the alumina, phosphor, stabilizer, and sintering aid included in the photoconversion member composition of the present invention may be included in the ranges of 60 to 98 wt%, 1 to 39 wt%, 0.01 to 1 wt%, and 0.1 to 3 wt%, respectively.

[0076] Each raw material is prepared in powder form, and their mixing can be performed by dry or wet mixing.

[0077] In the case of wet mixing, water or an organic solvent may be used as the solvent, and the organic solvent may include acetone, methyl ethyl ketone, methanol, ethanol, toluene, etc. The composition slurry prepared by including the solvent is prepared into a powder-type mixture by removing the solvent and drying after mixing is completed.

[0078] The powder-form composition that has been mixed is compressed to form a molded body (S220).

[0079] The mixed powder is injected into a mold, compressed, and formed into pellets in the shape of a plate or disk.

[0080] The molding method is not particularly limited as long as it can achieve the desired shape. For example, a mixed powder can be first subjected to uniaxial pressure molding, followed by cold isostatic pressing (CIP) to produce a ceramic phosphor plate with a predetermined shape and size. This compression process produces a molded body with a uniform, high density.

[0081] The manufactured molded body is subjected to primary heat treatment in an air atmosphere (S230).

[0082] The manufactured ceramic phosphor plate is heat treated in an air atmosphere (In Air) to perform primary sintering.

[0083] For example, the primary heat treatment for sintering the ceramic plate of the present invention may be performed at a temperature ranging from 1000 to 1650°C. The primary heat treatment process in an air atmosphere promotes surface activation of alumina particles, strengthening inter-particle bonding, thereby improving the density of the ceramic structure.

[0084] The first heat-treated molded body is subjected to a second heat treatment in a reducing atmosphere (S240).

[0085] The reducing atmosphere may be an inert gas such as nitrogen (N2), argon (Ar), or hydrogen (H2), and may be performed under reduced pressure or vacuum. The secondary heat treatment may be performed at a temperature ranging from 1500 to 1800°C.

[0086] Secondary heat treatment in a reducing atmosphere increases the diffusion rate of alumina, promoting sintering and resulting in a more dense ceramic structure.

[0087] Post-processing is performed on the molded body that has undergone secondary heat treatment (S250).

[0088] Post-processing treatments may include annealing, thinning, surface polishing, and surface coating, and these post-processing treatments may be applied singly or in combination.

[0089] Below, the operation and effect of the invention will be examined in more detail through specific examples of the invention.

[0090] (Example 1)

[0091] Alumina with a purity of 99.9% and an average particle size of 0.2㎛ was used as the matrix, and (LuY)3Al5O2 was used as the fluorescent material. 12 :Ce 3+ As a series (Lu a Y b Ce c )3Al5O 12(Here, 0≤a<1, 0≤b<1, 0<c≤0.1, a+b+c=1) was applied. The phosphor was applied with particles having an average particle diameter of 20㎛. In addition, MgF2 and BaF2 were used as sintering aids, CeO2 was applied as a stabilizer, and the stabilizer was applied with particles having an average particle diameter of 1㎛.

[0092] Additionally, each raw material was mixed as 92.4 wt% alumina, 7 wt% phosphor, 0.1 wt% stabilizer, and 0.5 wt% sintering aid.

[0093] The above mixed composition was prepared as a plate sample for measuring optical properties, and the process of preparing the plate sample with the photoconversion member composition was performed by the steps S210 to S240 described above. At this time, the first heat treatment was performed at 1200°C, and the second heat treatment was performed at 1800°C, respectively.

[0094] (Examples 2 to 5)

[0095] Compositions were prepared containing the same alumina, phosphor, stabilizer, and sintering aid as in Example 1, but with the stabilizer content varied to 0.2 wt%, 0.3 wt%, 0.4 wt%, and 0.5 wt%, respectively. The alumina content was adjusted corresponding to the stabilizer content, and plate samples were prepared using the same method as in Example 1.

[0096] (Example 6)

[0097] Alumina, phosphor, and sintering agent were applied in the same manner as in Example 1, except that Ce2O3 was used as a stabilizer. In this case, the stabilizer was included in an amount of 0.3 wt% of the total composition weight, and the alumina was included in an amount of 92.2 wt%. The average particle size of the stabilizer was also the same as in Example 1.

[0098] The method for manufacturing a ceramic plate using the manufactured composition was applied in the same manner as in Example 1.

[0099] (Comparative example)

[0100] Alumina, phosphor, and sintering aid were applied using the same materials as in the examples, except that the stabilizer was not included. Accordingly, a composition was prepared with 92.5 wt% of alumina, 7 wt% of phosphor, and 0.5 wt% of sintering aid based on the total composition weight.

[0101] The ceramic phosphor plates manufactured in the examples and comparative examples were measured for light intensity by wavelength using a spectrophotometer to compare the spectral distribution.

[0102] Table 1 below summarizes the optical properties of ceramic phosphor plates manufactured using the compositions of examples and comparative examples according to the type and amount of stabilizer added.

[0103] Classification Stabilizer Type Content (wt%) Luminous flux (lm) Peak Wavelength (nm) Dominant Wavelength (nm) Example 1 CeO 2 0.18 2 4 4 2 4 5 2 Example 2 0.28 4 4 4 2 4 5 2 Example 3 0.39 6 4 4 2 4 5 3 Example 4 0.49 5 4 4 2 4 5 3 Example 5 0.59 2 4 4 3 4 5 3 Example 6 Ce 2 O 3 0.38 6 4 4 2 4 5 2 Comparative Example - 0 8 1 4 4 2 4 5 2

[0104] It was confirmed that there is practically no significant difference in the peak wavelength and dominant wavelength depending on the presence or absence of the stabilizer, the type of stabilizer, and the difference in the stabilizer content in the composition. That is, it can be seen that the ceramic phosphor plate manufactured from the photoconversion member composition of the present invention is activated by blue light having a maximum wavelength of 442 to 443 nm.

[0105] However, referring to the results in Table 1 above, it was found that there was a difference in the luminous flux of the ceramic phosphor plate between the comparative examples and examples with different types of stabilizers.

[0106] In the case of the comparative example that did not include a stabilizer, the luminous flux was the lowest, and as the content of CeO2 was increased while using it as a stabilizer, the luminous flux gradually increased, and when it was included at 0.3 wt%, the maximum luminous flux was measured.

[0107] The high luminous flux of the ceramic phosphor plate due to the stabilizer means that the plate can emit a lot of light even with a small energy input, suggesting that it has high energy efficiency.

[0108] Meanwhile, the plate of Example 6 using Ce2O3 as a stabilizer also showed a higher luminous flux than the comparative example, and it was confirmed that the luminous efficiency of the ceramic plate could be improved through this.

[0109] From the results of the examples presented in Table 1 above, it can be seen that high luminous efficiency can be achieved when the stabilizer is included in a proportion of 0.3 to 0.5 wt% with respect to the entire composition.

[0110] FIG. 3 shows the results of measuring the spectral distribution of a fluorescent plate according to the type and content of a stabilizer in a photoconversion member composition according to one embodiment of the present invention.

[0111] Fig. 3a shows the spectral distribution for the ceramic phosphor plates of Examples 1 to 5, and Fig. 3b shows the spectral distribution measurement results for the phosphor plates of Examples 3 and 6 and the comparative example.

[0112] Referring to Fig. 3a, when cerium(Ⅳ) oxide, i.e., CeO2, is applied as a stabilizer, the maximum wavelength of the peak appears to be substantially the same regardless of the stabilizer content. However, a difference can be confirmed depending on the stabilizer content in the emission peak measured between 500 and 700 nm.

[0113] That is, as described above in the results of Table 1, it can be confirmed that the light intensity is increased in the examples including the stabilizer compared to the comparative examples without the stabilizer, and the effect is particularly remarkable when the stabilizer is included in the range of 0.3 to 0.5 wt%.

[0114] This can be interpreted as a result of suppressing the generation of internal pores due to excessive generation of oxygen pores, as the oxygen pores generated during the sintering process of alumina are controlled to a certain extent by the oxygen storage and release action of the stabilizer.

[0115] Meanwhile, referring to Fig. 3b, the spectral distributions when CeO2 and Ce2O3 were used as stabilizers showed that the light intensity at the emission peak at 500 to 700 nm was higher than when no stabilizer was used. However, when the same content of stabilizer was applied, CeO2 showed higher luminescence efficiency than Ce2O3.

[0116] These differences are believed to be due to the differences in the oxygen storage and release capacities of CeO2 and Ce2O3. That is, Ce2O3 has a lower oxidation state than CeO2, and thus has lower oxygen release and oxygen absorption capacities.

[0117] Therefore, it is expected that the effect will be greater when a substance with high oxygen storage and release capability is used as a stabilizer, and the performance of the ceramic phosphor plate can be optimized by adjusting the content in the photoconversion member composition according to the oxygen storage and release capability of the type of stabilizer described above.

[0118] FIG. 4 is a comparison of the light transmittance of a ceramic fluorescent plate according to the content of a stabilizer in a photoconversion member composition according to one embodiment of the present invention.

[0119] Referring to FIG. 4, it can be confirmed that the light transmittance of the ceramic plates of Comparative Example and Examples 1 to 5 is improved by the use of a stabilizer, similar to the spectral distribution measurement results described above.

[0120] In particular, the highest optical transmittance was achieved when the stabilizer was included at 0.3 to 0.4 wt%, compared to the comparative example without the stabilizer. This can be interpreted as a result of the stabilizer's action in suppressing oxygen vacancies and promoting sintering.

[0121] The photoconversion member composition of the present invention shows that the stabilizer effectively controls oxygen vacancies during the ceramic sintering process, thereby improving the reduction in luminous efficiency of the phosphor plate due to excessive oxygen vacancies.

[0122] Furthermore, the composition of the present invention, by applying alumina as a matrix, can achieve superior thermal properties and improved optical properties compared to conventional resin or glass matrixes. Accordingly, not only can the stability and reliability of LED devices be ensured, but it is also suitable for application to high-output LED devices and LDs.

[0123] Although each process is described as being executed sequentially in FIG. 2, this is merely an illustrative description of the technical idea of ​​one embodiment of the present invention. In other words, a person of ordinary skill in the art to which one embodiment of the present invention pertains may modify and apply various modifications and variations, such as changing the order of the processes described in each drawing and executing them or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present invention. Therefore, FIG. 2 is not limited to a chronological order.

[0124] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

[0125]

[0126] CROSS-REFERENCE TO RELATED APPLICATION

[0127]

[0128] *This patent application claims priority under 35 USC § 119(a) to Korean Patent Application No. 10-2024-0057772, filed in Korea on April 30, 2024, the entire contents of which are hereby incorporated by reference. Furthermore, if this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are hereby incorporated by reference.

Claims

1. As a composition for a photoconversion member, As a ceramic matrix material, polycrystalline alumina (Al2O3); A phosphor that performs a light conversion function; stabilizers; and Sintering preparation A composition for an alumina-based photoconversion member comprising:

2. In paragraph 1, The above sintering preparation is, A composition for an alumina-based photoconversion member, characterized in that it comprises at least one selected from alkaline earth metal halides, aluminum halides, zinc halides, and halides of rare earth elements.

3. In paragraph 1, The above polycrystalline alumina is, A composition for an alumina-based photoconversion member, characterized in that it has an average particle size in the range of 0.05 to 1㎛ with a purity of 99.5% or more.

4. In paragraph 1, The above fluorescent material is, A composition for an alumina-based photoconversion member, characterized in that it comprises at least one selected from the group consisting of garnet-based phosphors including yttrium aluminum garnet (YAG) series and lutetium aluminum garnet (LuAG) series, nitride-based phosphors, sulfide-based phosphors, silicate-based phosphors, and mixtures thereof.

5. In paragraph 4, The above fluorescent material is, A composition for an alumina-based photoconversion member, characterized in that it comprises a doped YAG type phosphor having an excitation band at a wavelength of 400 to 500 nm and an emission peak at a wavelength of 500 to 700 nm.

6. In paragraph 1, The above stabilizer is, A composition for an alumina-based photoconversion member, characterized in that it comprises at least one selected from zinc peroxide (ZnO2), zirconium oxide (ZrO2), cerium(III) oxide (Ce2O3), cerium(IV) oxide (CeO2), titanium dioxide (TiO2), and manganese oxide (MnO2).

7. In paragraph 6, The above stabilizer is, An alumina-based photoconversion member composition comprising 0.01 to 0.5 wt% of the above photoconversion member composition.

8. In paragraph 4, The above fluorescent material is, An alumina-based photoconversion member composition characterized in that it comprises 1 to 39 wt% of the composition for the photoconversion member.

9. In paragraph 2, The above sintering preparation is, An alumina-based photoconversion member composition characterized in that it is contained in an amount of 0.1 to 3 wt% compared to the above photoconversion member composition.

10. A ceramic phosphor plate characterized in that it is manufactured from a composition for a photoconversion member according to any one of claims 1 to 9.

11. In paragraph 10, The above ceramic phosphor plate is characterized in that the porosity is 1% or less.

Images