β-type sialon phosphor, light-emitting member, and light-emitting device

Abstract

The β-sialon phosphor according to the present invention is a β-sialon phosphor in which europium is present in the form of a solid solution, the β-sialon phosphor being configured such that, when an absorbance of a spectrum in spectra of the β-sialon phosphor which are determined by FT-IR is converted to a KM value by the Kubelka-Munk function and a KM value for a wavenumber of 3330 cm-1 is defined as A and a KM value of a wavenumber of 3220 cm-1 is defined as B, A and B satisfy the formula: 1.0 < A / B.

Description

[Technical Field]

[0001] The present invention relates to a β-sialon phosphor, a light-emitting member, and a light-emitting device. [Background technology]

[0002] Various developments have been made in the field of β-sialon phosphors. Patent Document 1, for example, describes a method for producing a β-sialon phosphor, which comprises heat-treating a composition containing silicon nitride containing aluminum, oxygen atoms, and europium, mixing the resulting mixture with a sodium hydroxide solution, and subjecting the resulting mixture to a first thermal base treatment at 70°C for 3 hours in the atmosphere, followed by a second thermal base treatment at 200°C for 2 hours in a nitrogen atmosphere (see, for example, Claims 1 and 3, paragraph 0009, Example 6, etc., of Patent Document 1). Furthermore, Patent Document 1 also discloses that the first temperature, which is the heating temperature for the first thermal base treatment, is between 50°C and 150°C (paragraph 0051). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-110206 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that the β-sialon phosphor obtained by the manufacturing method described in Patent Document 1 has room for improvement in terms of resistance to thermal degradation. [Means for solving the problem]

[0005] The inventors further investigated and found that the spectrum of the β-sialon phosphor measured by FT-IR has a wave number of 3330 cm -1 KM value / wave number 3220cm -1KM value, or wave number 3330 cm -1 KM value / wave number 3330cm -1 It was found that the thermal degradation resistance of β-sialon phosphors after thermal degradation tests can be stably evaluated by using the baseline KM value as an index. As a result of further intensive research, the present inventors have found that the above-mentioned index, wave number 3330 cm -1 KM value / wavenumber 3220cm -1 KM value, or wave number 3330 cm -1 KM value / wave number 3330cm -1 By appropriately controlling the baseline KM value to be a relatively high value, the decrease in diffuse reflectance and / or internal quantum efficiency after a thermal degradation test can be suppressed, and a β-sialon phosphor with excellent resistance to thermal degradation has been discovered, leading to the completion of the present invention.

[0006] According to one aspect of the present invention, there are provided the following β-sialon phosphor, light emitting member, and light emitting device.

[0007] 1. A β-sialon phosphor containing europium in solid solution, In the spectrum of the β-sialon phosphor obtained by FT-IR, the absorbance of the spectrum is converted into a KM value using the Kubelka-Munk function, and the absorbance at a wavenumber of 3330 cm -1 The KM value is A, and the wave number is 3220 cm -1 When the KM value of is B, A and B are 1.0 2. A β-sialon phosphor containing europium in solid solution, In the spectrum of the β-sialon phosphor obtained by FT-IR, the absorbance of the spectrum is converted into a KM value using the Kubelka-Munk function, and the absorbance at a wavenumber of 3330 cm -1 The KM value is A, and the wave number is 3030 cm -1 The KM value is C, and the wave number is 3600 cm -1 The KM value is D, and the wave number is 3330 cm -1 ​When the baseline KM value is E, E is calculated as E=(((DC)×3330) / (3600-3030))+C-(((DC)×3030) / (3600-3030)), A and E are 2.0 3. The β-sialon phosphor according to 1. or 2., A β-sialon phosphor with a diffuse reflectance of 90% or more at 800 nm. 4. The β-sialon phosphor according to any one of 1. to 3., A β-sialon phosphor that maintains a diffuse reflectance of 96% or more at 500 nm after being heated at 250°C for 5 hours in the atmosphere. 5. The β-sialon phosphor according to any one of 1. to 4., A β-sialon phosphor with an absorption rate of 10% or less at 600 nm after being heated in air at 250°C for 5 hours.

[0008] 6. A light-emitting element; a wavelength converter that converts light irradiated from the light emitting element and emits the converted light; A light emitting member comprising: The wavelength converter comprises the β-sialon phosphor according to any one of 1. to 5. Illuminating component.

[0009] 7. A light-emitting device comprising the light-emitting member described in 6. [Effects of the Invention]

[0010] According to the present invention, there are provided a β-sialon phosphor having excellent resistance to thermal degradation, and a light emitting member and a light emitting device using the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing infrared absorption spectra showing the relationship between KM value and wave number when FT-IR is measured for the β-sialon phosphors of each Example and each Comparative Example. [Figure 2] ​FIG. 2 is a cross-sectional view schematically showing the structure of an LED package used in a reliability test. [Figure 3] The results of the reliability test of the LED package are shown. DETAILED DESCRIPTION OF THE INVENTION

[0012] An outline of the β-sialon phosphor of this embodiment will be described.

[0013] The β-sialon phosphor is a β-sialon phosphor in which europium is dissolved in a solid solution. In the spectrum of the β-sialon phosphor obtained by FT-IR, the absorbance of the spectrum was converted into a KM value using the Kubelka-Munk function, and the absorbance at a wavenumber of 3330 cm -1 The KM value is A, and the wave number is 3220 cm -1 The KM value is B, and the wave number is 3030 cm -1 The KM value is C, and the wave number is 3600 cm -1 The KM value is D, and the wave number is 3330 cm -1 When the baseline KM value is E, E is calculated as E = (((DC) x 3330) / (3600-3030)) + C - (((DC) x 3030) / (3600-3030)). In the β-sialon phosphor of the first embodiment, A and B are each 1.0 In the β-sialon phosphor of the second embodiment, A and E are 2.0

[0014] According to the findings of the present inventors, it has been found that the state of the oxide layer on the surface of a β-sialon phosphor can be evaluated based on the infrared absorption spectrum of the β-sialon phosphor determined by FT-IR. In the infrared absorption spectrum, 3330 cm -1 is the NH group, 3220cm -1 is Si-OH, 3600cm -1 and 3030cm -1 indicates a location where there is little absorbing component. Then, the wave number 3330 cm -1 KM value / wave number 3220cm -1 ​​The ratio of KM values ​​(A / B) and the wave number 3330 cm -1 KM value / wave number 3330cm -1 The ratio (A / E) of the baseline KM values ​​indicates the amount of NH groups derived from the surface nitride of the β-sialon phosphor. The amount of NH groups can be used to evaluate the stability of the oxide layer on the surface of the β-sialon phosphor. For example, if an unstable oxide layer containing a large amount of Si-OH is formed on the surface of a β-SiAlON phosphor, excess absorption due to defects derived from Si-OH increases after the thermal degradation test, resulting in a decrease in the diffuse reflectance and internal quantum efficiency after the thermal degradation test.

[0015] The lower limit of A / B is, for example, more than 1.0, preferably 1.1 or more, and more preferably 1.3 or more, which can improve the diffuse reflectance and internal quantum efficiency after a thermal degradation test. The upper limit of A / B is, for example, 10.0 or less, preferably 4.0 or less, and more preferably 2.5 or less, thereby improving the heat degradation resistance.

[0016] The lower limit of A / E is, for example, 2.0 or more, preferably 2.3 or more, and more preferably 2.6 or more, which can improve the diffuse reflectance and internal quantum efficiency after a thermal degradation test. The upper limit of A / E is, for example, 15.0 or less, preferably 10.0 or less, and more preferably 7.0 or less, which can improve heat degradation resistance.

[0017] In this embodiment, it is possible to control the above A / B and A / E by appropriately selecting, for example, the type and amount of each component contained in the β-sialon phosphor, the preparation method of the β-sialon phosphor, etc. Among these, for example, applying an alkali treatment to the β-sialon phosphor, particularly applying an alkali treatment in which the surface of the β-sialon phosphor is heated in a state where there is substantially no water present, can be cited as a factor for setting the above A / B and A / E within the desired numerical range.

[0018] According to this embodiment, reduction in diffuse reflectance and / or internal quantum efficiency after a heat deterioration test is suppressed, and a β-type sialon phosphor excellent in heat deterioration resistance can be realized. By using such a β-type sialon phosphor in a light-emitting member or a light-emitting device, heat reliability can be improved.

[0019] Hereinafter, the β-type sialon phosphor of this embodiment will be described in detail.

[0020] The β-type sialon phosphor of this embodiment is extremely useful as a phosphor for a light source such as a Light Emitting Diode (hereinafter referred to as LED).

[0021] The β-type sialon phosphor can absorb blue light in the wavelength range of, for example, 420 nm to 480 nm and emit light having a peak wavelength in the range exceeding 480 nm and not exceeding 800 nm.

[0022] The β-type sialon phosphor is not particularly limited as long as it can be used as a phosphor, but is composed of europium-doped β-type sialon in which europium is solid-dissolved.

[0023] The europium-doped β-type sialon phosphor has the general formula Si 6-z Al z O z N 8-z :Eu 2+ (0 < z ≤ 4.2). In the general formula Si 6-z Al z O z N 8-z :Eu 2+ the z value and the europium content are not particularly limited, but the z value is, for example, more than 0 and not more than 4.2, and is preferably 0.005 or more and 1.0 or less from the viewpoint of further improving the emission intensity of the europium-doped β-type sialon phosphor. Also, the europium content in the europium-doped β-type sialon phosphor is preferably, for example, 0.1 mass% or more and 2.0 mass% or less.

[0024] The β-sialon phosphor may be in powder form and configured to have an average particle diameter d50 of, for example, 0.1 μm to 50 μm, preferably 0.25 μm to 40 μm, and more preferably 0.5 μm to 30 μm. By setting it to the upper limit or less, variations in the chromaticity of the emitted color can be suppressed. By setting it to the lower limit or more, brightness can be improved.

[0025] The average particle diameter d50 is a value calculated from the volume average diameter measured by a laser diffraction scattering method. The particle size distribution was measured according to the laser diffraction / scattering method described in JIS R 1629:1997, "Method for measuring particle size distribution of fine ceramic raw materials by laser diffraction / scattering." A particle size distribution analyzer (Microtrac-Bell Corporation, product name: "Microtrac MT3300EX II") was used for the measurement. Specifically, 0.1 g of the target phosphor was first added to 100 mL of ion-exchanged water and dispersed for 3 minutes using an ultrasonic homogenizer (Nihon Seiki Seisakusho Co., Ltd., product name: "Ultrasonic Homogenizer US-150E," tip size: φ20, amplitude: 100%, oscillation frequency: 19.5 kHz, amplitude: approximately 31 μm) to prepare the measurement sample. The particle size was then measured using the particle size distribution analyzer.

[0026] The 800 nm diffuse reflectance of the β-sialon phosphor is, for example, 90% or more, preferably 92% or more, and more preferably 94% or more, thereby realizing a β-sialon phosphor with excellent optical properties.

[0027] The β-sialon phosphor maintains a 500 nm diffuse reflectance of, for example, 96% or more, preferably 97% or more, and more preferably 98% or more after being heated in the atmosphere at 250°C for 5 hours, thereby realizing a β-sialon phosphor with excellent thermal degradation resistance and optical properties. The diffuse reflectance retention rate (%) is calculated by dividing the 500 nm diffuse reflectance after heating at 250°C for 5 hours in the atmosphere by the 500 nm diffuse reflectance before heating at 250°C for 5 hours in the atmosphere x 100.

[0028] The β-sialon phosphor has an absorptance at 600 nm after being heated in the atmosphere at 250°C for 5 hours of, for example, 10% or less, preferably 9% or less, and more preferably 8% or less, thereby realizing a β-sialon phosphor with excellent heat degradation resistance and optical properties.

[0029] Next, a method for producing the β-sialon phosphor of this embodiment will be described.

[0030] An example of a method for producing a β-sialon phosphor of this embodiment includes a preparation step of preparing a β-sialon phosphor, and an alkali treatment step of subjecting the surface of the β-sialon phosphor to alkali treatment.

[0031] The preparation step for preparing the β-sialon phosphor may be performed by a known method, but may also include, for example, a firing step of mixing raw material powders containing silicon, aluminum, and an activator element and firing the mixture to obtain a fired product, and at least one or more post-treatment steps of subjecting the fired product after the firing step to a crushing / pulverization treatment, classification treatment, annealing treatment, acid treatment, etc. The post-treatment steps can be performed in any order. The alkali treatment step may be carried out after the classification treatment, or after the acid treatment.

[0032] The firing temperature in the firing step is, for example, 1800°C or higher and 2100°C or lower, preferably 1850°C or higher and 2050°C or lower. By setting the firing temperature to the above lower limit or higher, the luminescence intensity can be improved. The firing step may be performed multiple times. In addition, when firing is performed for the second or subsequent times, part of the raw materials may be added.

[0033] The ambient temperature during the annealing step is, for example, 1100°C or higher and 1800°C or lower, preferably 1300°C or higher and 1750°C or lower. By setting the annealing temperature to the above lower limit or higher, the emission intensity can be improved. By setting the annealing temperature to the above upper limit or lower, the crystallinity can be improved and a decrease in the emission peak intensity can be suppressed.

[0034] The atmospheric gas used in the annealing step is selected from the group consisting of a rare gas of an element in Group 18 of the periodic table, such as argon gas, an inert gas, such as nitrogen gas, hydrogen gas, and a mixed gas of hydrogen gas and argon gas.

[0035] The annealing process's improved properties are achieved over a wide range of atmospheric pressures, from reduced pressure to increased pressure, but pressures lower than 1 kPa are undesirable because they accelerate the decomposition of the β-sialon phosphor. Furthermore, by increasing the atmospheric pressure, it is possible to broaden the range of other conditions required to achieve the annealing effect (lower temperature, shorter time), but if the atmospheric pressure is too high, the annealing effect will plateau and a specialized, expensive annealing device will be required. Therefore, considering mass production, the preferred atmospheric pressure is 10 MPa or less, and more preferably less than 1 MPa.

[0036] If the treatment time in the annealing step is too short, the effect of improving crystallinity is low, and if it is too long, the annealing effect reaches a plateau, so the treatment time is from 1 hour to 24 hours, preferably from 2 hours to 10 hours.

[0037] Furthermore, the manufacturing method of this embodiment may include an acid treatment step of immersing the β-sialon phosphor in an acid solution after the annealing step, which can further improve the properties of the phosphor.

[0038] The acid treatment step preferably includes a step of immersing the β-sialon phosphor in an acid solution, separating the β-sialon phosphor from the acid using a filter or the like, and washing the separated β-sialon phosphor with water. The acid treatment can remove decomposition products of the β-sialon phosphor crystals that occur during the annealing step, thereby improving the fluorescent properties. Examples of acids used in the acid treatment include hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid, either singly or in combination. A mixed acid consisting of hydrofluoric acid and nitric acid is preferred, as it is suitable for removing decomposition products. The temperature of the acid solution during the acid treatment can be room temperature, but it is preferable to heat it to between 50°C and 90°C to enhance the effectiveness of the acid treatment.

[0039] In this manner, a β-sialon phosphor containing the activator element in solid solution can be obtained. If necessary, known processes may be added, such as post-treatments such as crushing / disintegration, purification, drying, sieving / classification, etc. The step of adjusting the particle size, such as sieving or classification, may be carried out at any time after the firing step, the annealing step, or the acid treatment step.

[0040] In the alkali treatment step, the β-sialon phosphor is heated in a state in which a solid basic substance is attached to the surface.

[0041] Examples of basic substances include alkali metal hydroxides, alkali metal carbonates, hydroxides of Group 2 elements of the periodic table, oxides of Group 2 elements of the periodic table, and quaternary ammonium. An example of the basic substance includes one or more selected from the group consisting of NaOH, KOH, LiOH, CaO, SrO, Na2CO3, and NaHCO3.

[0042] The solid basic substance may be a basic substance that is solid at room temperature, or may be a basic solution prepared by dissolving a basic substance in a solvent such as water and then removing the solvent at a temperature below 50° C. to dry the basic substance. For example, the basic substance may be vacuum dried at a temperature below 50° C.

[0043] To attach a solid basic substance to the surface, for example, a powder of β-sialon phosphor may be mixed with a basic substance that is solid at room temperature. Alternatively, a mixed solution containing a powder of a β-sialon phosphor, a basic substance, and water may be vacuum-dried at a temperature below 50°C to remove the water from the basic substance and adhere the solid basic substance to the surface of the β-sialon phosphor. Removing the solvent such as water at a relatively low temperature below 50°C can suppress the formation of Si-OH groups on the surface of the β-sialon phosphor.

[0044] During the alkali treatment step, the β-sialon phosphor is heated with the solid basic substance attached to its surface in an environment substantially free of water. The absence of water means that moisture (humidity) contained in the exposure atmosphere outside the solid basic substance is allowed, or moisture in hydrates contained in the solid basic substance is allowed.

[0045] In the alkali treatment step, the β-sialon phosphor can be heated from room temperature. Room temperature may be, for example, 23°C or 25°C. The upper limit of the heating temperature is not particularly limited, but may be, for example, 400°C or lower, or 450°C or lower.

[0046] In the alkali treatment step, heating may be performed from room temperature at a temperature rise rate of, for example, 0.1°C / min to 100°C / min, preferably 5°C / min to 50°C / min, and more preferably 1°C / min to 30°C / min.

[0047] In the alkali treatment step, the heating atmosphere may be, for example, an air atmosphere, a vacuum atmosphere, or an inert gas atmosphere such as a rare gas atmosphere or nitrogen atmosphere.

[0048] The method for producing a β-sialon phosphor of this embodiment may further include, after the alkali treatment step, a step of washing the obtained β-sialon phosphor with water. The water used for washing is removed by drying using a known method. After the alkali treatment step, post-treatments such as crushing / disintegration, refining, drying, sieving / classification, etc. may be carried out as necessary.

[0049] [Wavelength converter, light-emitting component] The light-emitting component of this embodiment comprises a light-emitting element and a wavelength converter that converts light irradiated from the light-emitting element and emits light, and the wavelength converter has the above-mentioned β-sialon phosphor.

[0050] An example of the method for manufacturing a wavelength conversion member of the present embodiment includes a step of manufacturing a wavelength conversion member using a β-sialon phosphor obtained by the method for manufacturing a β-sialon phosphor.

[0051] The wavelength converter of this embodiment converts light irradiated from a light-emitting element to emit light, and includes the above-mentioned β-sialon phosphor. The wavelength converter may be composed only of the β-sialon phosphor, or may include a base material in which the β-sialon phosphor is dispersed. Known base materials can be used, such as glass, resin, and inorganic materials.

[0052] The shape of the wavelength converter is not particularly limited, and it may be configured in a plate shape, or may be configured to seal a part of the light emitting element or the entire light emitting surface.

[0053] [Light-emitting device]

[0054] The light emitting device according to this embodiment includes a light emitting member including a light source (light emitting element) and the wavelength converter. By combining a light source with a wavelength converter, it is possible to emit light with high luminous intensity.

[0055] An example of a method for manufacturing a light emitting device according to this embodiment includes a step of mounting a wavelength conversion member obtained by the method for manufacturing a wavelength conversion member on a light emitting surface of a light source.

[0056] An example of a light emitting device is an LED package. The LED package may include a light emitting source (LED chip), a substrate (lead frame) on which the light emitting source is mounted, and a wavelength converter covering the light emitting source. The LED chip may emit light with a wavelength of 300 nm to 500 nm, which is near ultraviolet to blue light. The LED chip and the lead frame may be electrically connected by bonding wires. The wavelength converter may be covered with a cap made of synthetic resin.

[0057] The wavelength converter may contain the β-sialon phosphor, but may also contain other phosphors. Examples of other phosphors include an α-sialon phosphor, a KSF phosphor, a CASN phosphor, a SCASN phosphor, and a YAG phosphor. These phosphors may be used alone or in combination of two or more.

[0058] In the case of a light-emitting device using the above-mentioned β-sialon phosphor, by irradiating near-ultraviolet light or visible light containing a wavelength of 300 nm or more and 500 nm or less as an excitation source, the light emits green light with a peak wavelength in the range of 520 nm or more and 560 nm or less. Therefore, by combining a near-ultraviolet LED chip or a blue LED chip and a β-sialon phosphor as a light source with one or more red-, blue-, yellow-, or orange-emitting phosphors, it is possible to produce white light.

[0059] For example, a combination of a β-sialon phosphor that exhibits green color and a KSF-based phosphor that exhibits red color can be used favorably in LEDs for backlights suitable for TVs with high color rendering. [Example]

[0060] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0061] <Preparation of β-SiAlON phosphor>

[0062] (Comparative Example 1) (1) The raw materials were weighed into a container so that silicon nitride (Si3N4) was 98.4% by mass, aluminum nitride (AlN) was 1.0% by mass, and europium oxide (Eu2O3) was 0.6% by mass, and mixed using a V-type mixer (manufactured by Tsutsui Scientific Machinery Co., Ltd.) to obtain a mixture. The obtained mixture was passed through a sieve with 250 μm openings to remove aggregates, thereby obtaining a raw material composition. The aggregates that did not pass through the sieve were crushed, and the particle size was adjusted so that they would pass through the sieve.

[0063] (2) 200 g of the raw material composition prepared as described above was weighed into a cylindrical boron nitride container with a lid (a molded product made by Denka Co., Ltd., primarily composed of boron nitride (trade name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). The container was then placed in an electric furnace equipped with a carbon heater, heated to 2000°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG), and heated at 2000°C for 10 hours (firing step). After heating, the sample that had become loosely agglomerated in the container was placed in a mortar and crushed. After crushing, the sample was passed through a sieve with 250 μm openings to obtain a powdery first fired body.

[0064] (3) Next, the first fired body was packed into a cylindrical boron nitride container, and the container was placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1450°C in an argon gas atmosphere (pressure: 0.025 MPaG), and heating was continued at 1450°C for 5 hours (annealing step). After heating, the loosely aggregated particles in the container were crushed in a mortar and mortar, and then passed through a 250 μm sieve to obtain powder.

[0065] (4) Next, the powder obtained in (3) was added to a mixed acid of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) (a 1:1 volume ratio of hydrofluoric acid and nitric acid), and acid treatment was performed for 30 minutes while stirring at 75°C. After the acid treatment, the stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder refined by the acid treatment were removed. Distilled water was then added and the mixture was stirred again. The stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder were removed. This procedure was repeated until the pH of the aqueous solution was 8 or less and the supernatant was transparent. The resulting precipitate was filtered, dried, and passed through a sieve with 250 μm openings, yielding a europium-activated β-sialon phosphor of Comparative Example 1.

[0066] (Comparative Example 2) As in Comparative Example 1, the powder of β-type sialon phosphor obtained in (4) was heated in an air atmosphere at a heating rate of 10°C / min, heated at 200°C for 1 hour (heating step), and passed through a sieve with 250 μm openings to obtain the europium-activated β-type sialon phosphor of Comparative Example 2.

[0067] Example 1 In the same manner as in Comparative Example 1, the powder of the β-type sialon phosphor obtained in (4) was mixed with a 50% by mass aqueous solution of sodium hydroxide, and then the mixed solution was filtered. The residue was vacuum dried at 45°C to obtain a dried powder, which was then heated in an air atmosphere from 25°C at a heating rate of 10°C / min to 200°C for 1 hour (alkali treatment step), washed with water, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor of Example 1.

[0068] Examples 2 to 9 Europium-activated β-sialon phosphors of Examples 2 to 9 were obtained in the same manner as in Example 1, except that the conditions (type and concentration of basic substance, heating conditions) in the alkali treatment step were changed to those shown in Table 1.

[0069] [Table 1]

[0070] The β-sialon phosphors of each example and comparative example were evaluated for the following characteristics and evaluation items.

[0071] (Diffuse reflectance before and after thermal degradation test) The diffuse reflectance of the β-sialon phosphor was measured using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). Baseline correction was performed using a standard reflector (Spectralon), a solid sample holder filled with β-type sialon phosphor was set, and diffuse reflectance was measured in the wavelength range of 500 to 850 nm. The diffuse reflectance (%) at 500 nm was measured.

[0072] <600nm light absorption rate of β-type sialon phosphor> A standard reflector (Spectralon® manufactured by Labsphere) with a reflectance of 99% was set at the side opening of the integrating sphere. Monochromatic light separated into 600 nm wavelengths from a light source (Xe lamp) was introduced into the integrating sphere via an optical fiber, and the reflected light spectrum was measured using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). The number of incident light photons (Qex(600)) was calculated from the spectrum in the wavelength range of 590 to 610 nm. Next, the concave cell was filled with β-sialon phosphor so that the surface was smooth, and then placed in the opening of the integrating sphere. Monochromatic light with a wavelength of 600 nm was irradiated, and the incident and reflected light spectrum was measured using a spectrophotometer. The incident reflected light photon count (Qref(600)) was calculated from the obtained spectral data. The incident reflected light photon count (Qref(600)) was calculated over the same wavelength range as the incident light photon count (Qex(600)). The 600 nm light absorptance was calculated from the obtained two types of photon counts using the following formula. 600 nm light absorption rate = ((Qex(600) - Qref(600)) / Qex(600)) × 100

[0073] <Internal quantum efficiency of β-type sialon phosphor> A standard reflector (Spectralon® manufactured by Labsphere) with a reflectance of 99% was set at the side opening of the integrating sphere. Monochromatic light separated into 455 nm wavelengths from a light source (Xe lamp) was introduced into the integrating sphere via an optical fiber, and the reflected light spectrum was measured using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm. Next, the concave cell was filled with β-sialon phosphor so that the surface was smooth, and the cell was placed in the opening of the integrating sphere. Monochromatic light with a wavelength of 455 nm was irradiated, and the excitation reflected light spectrum was measured using a spectrophotometer. The number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated from the obtained spectral data. The number of excitation reflected light photons was calculated in the same wavelength range as the excitation light photon count, and the number of fluorescence photons was calculated in the range of 465 to 800 nm. The external quantum efficiency, light absorptance, and internal quantum efficiency were calculated from the obtained three types of photon counts using the following formulas. Absorbance of 455 nm excitation light = ((Qex-Qref) / Qex) x 100 Internal quantum efficiency = (Qem / (Qex-Qref)) x 100 External quantum efficiency = (Qem / Qex) x 100 Internal quantum efficiency (%) = External quantum efficiency / Light absorption rate (Absorption rate of 455 nm excitation light)

[0074] Furthermore, 4 g of the β-sialon phosphor was placed in a porcelain crucible with a lid (Kennis, capacity 30 mL), the lid was closed, and a heat treatment (thermal degradation test) was carried out in an air atmosphere at 250°C for 5 hours (heat increase 10°C / min). After that, the phosphor was passed through a sieve with 250 μm openings, and the diffuse reflectance (%) at 500 nm and 800 nm, the absorbance at 600 nm, and the internal quantum efficiency (%) were measured in the same manner as above.

[0075] Furthermore, when a standard sample of β-SiAlON phosphor (manufactured by SiAlON Corporation, NIMS Standard Green lot No. NSG1301) was measured for internal quantum efficiency, absorptance of excitation light at 600 nm, diffuse reflectance at 800 nm, and diffuse reflectance at 500 nm according to the above-mentioned measurement methods, the results were: internal quantum efficiency 74.8%, absorptance of excitation light at 600 nm 7.6%, diffuse reflectance at 800 nm 95.7%, and diffuse reflectance at 500 nm 80.4%.

[0076] The measured values ​​of the internal quantum efficiency, the absorbance of excitation light at 600 nm, the diffuse reflectance at 800 nm, and the diffuse reflectance at 500 nm may vary depending on the manufacturer of the measuring device, the production lot number, etc. Therefore, the values ​​measured by the measurement method described in this specification are used as the various measured values. However, when the manufacturer of the measuring device, the production lot number, etc. are changed, the measured values ​​can be corrected using the measured values ​​of the standard sample of the β-sialon phosphor described above as the reference value.

[0077] For the β-sialon phosphor of each example and comparative example, the infrared absorption spectrum was determined by FT-IR, and the absorbance of the spectrum was converted into a KM value using the Kubelka-Munk function. The Kubelka-Munk function (KM value) spectrum can be obtained by Fourier transform infrared absorption analysis (FT-IR). Measurements were performed using a PerkinElmer Spectrum One. The measurement sample can be prepared by pelletizing the β-sialon phosphor without diluting it. Here, in this specification, the "value of the Kubelka-Munk function" is a function that converts the reflectance of a substance into a value that serves as an index of the absorption specific to the substance, and can be obtained by dividing the extinction coefficient by the scattering coefficient (extinction coefficient / scattering coefficient). For each example and comparative example, the KM value and wave number (cm -1 ) is shown in Figure 1. The baseline is 3600 cm -1 and 3030cm -1 The line connecting the values ​​of In Figure 1, 3330 cm -1 is the NH group, 3220cm -1 is Si-OH, 3600cm -1 and 3030cm -1 indicates a location with few absorbing components.

[0078] Compared with Comparative Examples 1 and 2, the β-sialon phosphors of Examples 1 to 9 had higher 500 nm diffuse reflectance and higher internal quantum efficiency after the thermal degradation test, demonstrating superior resistance to thermal degradation.

[0079] <Reliability test> The reliability of the LED packages incorporating the alkali-treated phosphor particles of each example and the phosphor particles of each comparative example was evaluated as follows: The results of the reliability test are shown in FIG. The LED package used was one conforming to the structure of the light emitting device shown in Figure 2. The alkali-treated phosphor particles or phosphor particles were mounted on the LED package by wire-bonding the lead frame to the electrode on the top of the LED located at the bottom of the recessed case, and then injecting the alkali-treated phosphor particles or phosphor particles mixed with liquid silicone resin (KER6150, Shin-Etsu Chemical Co., Ltd.) into the recessed case using a microsyringe. The phosphor concentration in the phosphor + resin was 10.5 wt%. After mounting the alkali-treated phosphor particles or phosphor particles, the LED was left to stand in a room temperature, low humidity environment (MacDry MCU-201A, ERC Co., Ltd.) for 15 hours, and then cured at 150°C for 1 hour. The LED used had a peak emission wavelength of 448 nm and a chip size of 1.0 mm x 0.5 mm. The luminous flux of the LED packages incorporating the alkali-treated phosphor particles of each example and the phosphor particles of each comparative example obtained in the above manner was measured and designated as the initial value L0. Furthermore, the LED packages were left for 250 hours with a current of 300 mA applied at 85°C and 85% RH, then removed and dried at room temperature. The luminous flux L1 was measured and the reliability coefficient M (= L1 / L0 × 100) was calculated. The reliability test requires a reliability coefficient M of 80% or higher. This value can only be achieved with highly reliable alkali-treated phosphor particles. It was confirmed that the LED packages incorporating the alkali-treated phosphor particles of Examples 1 and 2 met the above-mentioned pass criteria.

[0080] This application claims priority based on Japanese Patent Application No. 2021-203850, filed on December 16, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0081] 10. Light-emitting device 20 Light-emitting element 30 Heatsink 40 cases 50 First lead frame 60 Second lead frame 70 Bonding Wire 72 Bonding Wire 80 Complex 82 Alkali-treated phosphor particles 84 Encapsulating material

Claims

1. A β-sialon phosphor containing europium as a solid solution, In the spectrum of the β-sialon phosphor obtained by FT-IR, the absorbance of the spectrum is converted into a KM value by the Kubelka-Munk function, and the absorbance at a wave number of 3330 cm －１ The KM value is A, and the wave number is 3220 cm －１ When the KM value of is B, A β-sialon phosphor, wherein A and B satisfy 1.0<A / B.

2. A β-sialon phosphor containing europium as a solid solution, In the spectrum of the β-sialon phosphor obtained by FT-IR, the absorbance of the spectrum is converted into a KM value by the Kubelka-Munk function, and the absorbance at a wave number of 3330 cm －１ The KM value is A and the wave number is 3030 cm －１ The KM value is C and the wave number is 3600 cm －１ The KM value is D, and the wave number is 3330 cm －１ When the baseline KM value is E, E is calculated as E = (((D - C) x 3330) / (3600 - 3030)) + C - (((D - C) x 3030) / (3600 - 3030)), A β-sialon phosphor, wherein A and E satisfy 2.0<A / E.

3. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor having a diffuse reflectance of 90% or more at 800 nm.

4. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor having a 500 nm diffuse reflectance retention rate of 96% or more after being heated at 250°C for 5 hours in the atmosphere.

5. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor having an absorptivity of 10% or less at 600 nm after being heated at 250°C for 5 hours in the atmosphere.

6. A light-emitting element; a wavelength converter that converts light irradiated from the light emitting element and emits the converted light; A light emitting member comprising: The wavelength converter comprises the β-sialon phosphor according to claim 1 or 2. Illuminating component.

7. A light emitting device comprising the light emitting member according to claim 6.

8. A method for producing a β-sialon phosphor according to claim 1 or 2, comprising: a preparation step of preparing a β-sialon phosphor; an alkali treatment step of heating the β-sialon phosphor with a solid basic substance attached to its surface in a substantially water-free environment; Method for producing β-sialon phosphor.

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