β-type sialon phosphor particles

Abstract

According to the present invention, β-type sialon phosphor particles have a particle diameter (D50) at a cumulative volume frequency of 50% in a particle size distribution measured via a wet laser diffraction particle size distribution method of 5-150 μm, and satisfy condition i. Condition i: When surfaces of the β-type sialon phosphor particles are observed at 50,000-times magnification via a scanning electron microscope (SEM), a stripe pattern can be ascertained.

Description

β-type sialon phosphor particles

[0001] The present invention relates to β-type sialon phosphor particles. More specifically, it relates to β-type sialon phosphor particles, β-type sialon phosphor powder containing said β-type sialon phosphor particles, and a light-emitting device using said β-type sialon phosphor powder.

[0002] Various developments have been made regarding β-type sialon phosphors. As an example of this type of technology, the technology described in Patent Document 1 is known. Patent Document 1 describes a method for producing a β-sialon phosphor, in which a first heat-treated product obtained by heat-treating a composition containing aluminum, oxygen atoms, and silicon nitride containing europium is mixed with an aqueous sodium hydroxide solution, a first thermal base treatment is performed in air at 70°C for 3 hours, and a second thermal base treatment is performed in a nitrogen atmosphere at 200°C for 2 hours (Patent Document 1, Claims 1, 3, Paragraph 0009, Example 6, etc.). The same document also indicates that the first temperature, which is the heating temperature for the first thermal base treatment, is 50°C or higher and 150°C or lower (Paragraph 0051).

[0003] Japanese Patent Publication No. 2017-110206

[0004] However, as a result of the inventors' investigations, it was found that the β-type sialon phosphor obtained by the manufacturing method described in Patent Document 1 above has room for improvement in terms of efficiently obtaining good luminescence characteristics.

[0005] The inventors investigated how to efficiently obtain higher brightness and focused on the fact that when a β-type sialon phosphor is emitted, the excitation light is reflected within the β-type sialon phosphor, reducing the efficiency of light extraction. Therefore, they hypothesized that the surface state of the β-type sialon phosphor has an effect and conducted further investigations. They found that the fringe pattern observed on the surface of a β-type sialon phosphor of a predetermined particle size using a scanning electron microscope (SEM) contributes to the suppression of light reflection. Further investigations led to the development of a new index, and it was found that by controlling light reflection using this index, a phosphor with high brightness can be efficiently realized, thus completing the present invention.

[0006] According to one aspect of the present invention, the following β-type sialon phosphor particles and related technologies are provided.

[0007] [1] Beta-type sialon phosphor particles having a particle size (D50) of 50% of the cumulative volume frequency of the particle size distribution measured by wet laser diffraction particle size distribution method, which is 5 to 150 μm, and satisfying the following condition i: (Condition i) When the surface of the beta-type sialon phosphor particles is observed at a magnification of 50,000x using a scanning electron microscope (SEM), a striped pattern can be confirmed. [2] Beta-type sialon phosphor particles as described in [1], wherein, in condition i, the striped pattern has a high-density striped region where the stripe density of the striped pattern in a 2.5 μm square area is 15 stripes / μm or more. [3] A β-type sialon phosphor particle according to [1] or [2], wherein, in condition i, the striped pattern has a stripe density of 15 stripes / μm or more, and the striped pattern has a linear region composed of straight stripes with a length of 1 μm or more. [4] A β-type sialon phosphor particle according to any one of [1] to [3], wherein, in condition i, the striped pattern has a stripe density of 15 stripes / μm or more in a 2.5 μm square area, and the striped pattern has a curved region composed of curved stripes. [5] A β-type sialon phosphor particle according to any one of [1] to [4], wherein, in condition i, the striped pattern has a medium-density striped region in a 2.5 μm square area where the stripe density of the striped pattern is 5 stripes / μm or more and less than 15 stripes / μm. [6] Beta-type sialon phosphor particles according to any one of [1] to [5], further satisfying condition ii. (Condition ii) When the surface of the beta-type sialon phosphor particles is observed with a scanning electron microscope (SEM) at a magnification of 50,000, no smooth region of 2.5 μm square or larger is observed. [7] Beta-type sialon phosphor powder containing beta-type sialon phosphor particles according to any one of [1] to [6]. [8] A light-emitting device comprising a light-emitting light source and a wavelength conversion member, wherein the wavelength conversion member comprises phosphor powder, and the phosphor powder comprises the beta-type sialon phosphor powder described in [7]. [9] The light-emitting device according to [8], wherein the light-emitting light source comprises an LED chip that generates light with a wavelength of 300 nm to 500 nm.

[0008] According to the present invention, β-type sialon phosphor particles capable of improving luminescence characteristics, and related technologies are provided.

[0009] This figure shows an image of β-type sialon phosphor particles observed using a scanning electron microscope (SEM). This figure shows a binarized scanning electron microscope (SEM) image of β-type sialon phosphor particles from Example 1. This figure shows a binarized scanning electron microscope (SEM) image of β-type sialon phosphor particles from Example 2. This figure shows a binarized scanning electron microscope (SEM) image of β-type sialon phosphor particles from Example 3. This figure shows a binarized scanning electron microscope (SEM) image of β-type sialon phosphor particles from Comparative Example 1.

[0010] <β-type Sialon phosphor particles> The β-type Sialon phosphor particles of this embodiment have a particle size (D50) at which the cumulative volume frequency of the particle size distribution measured by the wet laser diffraction particle size distribution method is 5 to 150 μm, and satisfy the following condition i.

[0011] (Condition i) When the surface of the β-type Sialon phosphor particles is observed at a magnification of 50,000x using a scanning electron microscope (SEM), a striped pattern can be confirmed.

[0012] The inventors devised a condition i to highly control the light reflection state on the surface of β-type sialon phosphor particles having a specific particle size. They found that by using β-type sialon phosphor particles that satisfy condition i, it is possible to improve brightness while reducing the amount of phosphor, thus completing the present invention. In other words, conventionally, when β-type sialon phosphors were emitted, the light emission tended to be reflected within the β-type sialon phosphor, reducing the efficiency of light extraction. In contrast, the β-type sialon phosphor of this embodiment suppresses the reflection of light emission within the β-type sialon phosphor, thereby increasing the efficiency of light extraction. As a result, a phosphor with high brightness can be efficiently realized.

[0013] In condition i above, the striped pattern is observed as a pattern due to differences in density when viewed at a magnification of 50,000x using a scanning electron microscope (SEM), and may be due to the shape of the surface of the β-type sialon phosphor particles. Specifically, it is preferable that the striped pattern is composed of wrinkles, grooves, steps, irregularities, etc. on the surface of the β-type sialon phosphor particles. Furthermore, the striped pattern only needs to be observed on a part of the surface of the β-type sialon phosphor particles and does not need to cover the entire surface of the β-type sialon phosphor particles. In addition, the spacing and length of the stripes in the striped pattern are not particularly limited and may be irregular. Furthermore, the shape of the stripes is not particularly limited and may be linear, a combination of curves and lines, or an irregular pattern.

[0014] For example, Figure 1 is a diagram showing an image of β-type Sialon phosphor particles observed using a scanning electron microscope (SEM). Figure 1 shows examples of high-density regions, medium-density regions, and linear regions, which will be described later. However, Figure 1 is an illustrative diagram and is not directly related to the present invention.

[0015] In condition i, it is preferable that the striped pattern has high-density striped regions where the stripe density of the striped pattern is 15 stripes / μm or more in a 2.5 μm square area. This makes it easier to improve the luminescence characteristics.

[0016] In condition i, it is preferable that the striped pattern has a medium-density striped region where the stripe density of the striped pattern in a 2.5 μm square area is 5 stripes / μm or more and less than 15 stripes / μm. This makes it easier to improve the luminescence characteristics.

[0017] In condition i, it is preferable that the striped pattern has a stripe density of 15 stripes / μm or more, and that the striped pattern has a linear region composed of linear stripes with a length of 1 μm or more. That is, it is preferable that the pattern has a region in which linear stripes with a length of 1 μm or more are arranged at a stripe density of 15 stripes / μm or more. This makes it easier to improve the luminescence characteristics. Furthermore, it is preferable that adjacent stripes in the linear region are substantially parallel to each other.

[0018] In condition i, it is preferable that the striped pattern has a stripe density of 15 stripes / μm or more in a 2.5 μm square area, and that the striped pattern has a curved region composed of curved stripes. That is, it is preferable to have a region in which curved stripes are arranged at a stripe density of 15 stripes / μm or more. This makes it easier to improve the luminescence characteristics. Furthermore, it is preferable that adjacent stripes in the curved region are substantially parallel to each other.

[0019] The β-type Sialon phosphor particles of this embodiment preferably also satisfy condition ii. This prevents light converted within the phosphor particles from being reflected off the particle surface and remaining inside the particles throughout the entire β-type Sialon phosphor particle, thereby increasing brightness more efficiently.

[0020] (Condition ii) When the surface of the β-type Sialon phosphor particle is observed with a scanning electron microscope (SEM) at a magnification of 50,000x, no smooth area of ​​2.5 μm square or larger is observed.

[0021] In other words, condition ii means that when the surface of the β-type Sialon phosphor particle is observed in 2.5 μm square areas at a magnification of 50,000x using a scanning electron microscope (SEM), there are no smooth areas where a striped pattern is not observed throughout the entire 2.5 μm square area, and some kind of striped pattern is observed. Furthermore, the shape of the smooth areas is not particularly limited.

[0022] Beta-type sialon phosphor particles that satisfy the above conditions i and ii can be realized, for example, by appropriately selecting the types and amounts of each component contained in the beta-type sialon phosphor, the particle size of the beta-type sialon phosphor, and the method of preparing the beta-type sialon phosphor. Among these, for example, controlling the conditions of firing and annealing (crystal growth) of the beta-type sialon phosphor, and the acid treatment conditions can create wrinkles or grooves by removing unwanted materials. In particular, controlling the temperature at which the gas is introduced during the annealing process is effective. The specifics will be explained later in the section on the method of producing beta-type sialon phosphor.

[0023] [Particle Size] The β-type Sialon phosphor particles of this embodiment have a particle size (D50) at which the cumulative volume frequency of the particle size distribution measured by the wet laser diffraction particle size distribution method is 5 to 150 μm, preferably 7 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. By setting the particle size (D50) to below the above upper limit, it is possible to obtain good brightness while suppressing variations in the chromaticity of the emitted color. On the other hand, by setting the particle size (D50) to above the above lower limit, it becomes easier to improve brightness.

[0024] The particle size (D50) can be measured specifically by the following procedure. (Procedure) The measurement is performed in accordance with the particle size distribution measurement method by laser diffraction and scattering described in JIS R 1629:1997 "Method for Measuring Particle Size Distribution of Fine Ceramics Raw Materials by Laser Diffraction and Scattering". A particle size distribution analyzer (Microtrac-Bell Co., Ltd., product name: "Microtrac MT3300EX II") is used for the measurement. First, 0.1 g of the phosphor to be measured is placed in 100 mL of deionized water, and the sample is dispersed for 3 minutes using an ultrasonic homogenizer (Nippon 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. After that, the particle size distribution is measured using the particle size distribution analyzer.

[0025] The particle size (D50) of β-type Sialon phosphor particles can be controlled by known methods, for example, by adjusting processing conditions such as grinding and classification, or by adjusting the manufacturing conditions of β-type Sialon phosphor particles.

[0026] The following describes other characteristics and configurations of the β-type Sialon phosphor particles of this embodiment.

[0027] The β-type Sialon phosphor particles of this embodiment are extremely useful as phosphors for light sources such as Light Emitting Diodes (hereinafter referred to as LEDs).

[0028] β-type sialon phosphor particles 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.

[0029] The β-type sialon phosphor particles are not particularly limited as long as they can be used as a phosphor, and are composed of europium-activated β-type sialon in which europium is dissolved.

[0030] The europium-activated β-type sialon phosphor particles have 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＋ In this case, 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 from the viewpoint of further improving the emission intensity of the europium-activated β-type sialon phosphor, it is preferably 0.005 or more and 1.0 or less. Also, the europium content in the europium-activated β-type sialon phosphor particles is preferably, for example, 0.1% by mass or more and 2.0% by mass or less.

[0031] <Manufacturing method of β-type sialon phosphor particles> Next, the manufacturing method of the β-type sialon phosphor particles of the present embodiment will be described.

[0032] An example of the manufacturing method of the β-type sialon phosphor particles of the present embodiment includes a mixing step of mixing raw material powders containing silicon, aluminum, an activating element, etc., a firing step of firing the mixture to obtain a fired product, and a post-treatment step such as a crushing and pulverizing treatment, a classification treatment, an annealing treatment, and an acid treatment. Hereinafter, the details of each step will be described.

[0033] [Mixing step] Raw material powders containing silicon, aluminum, and europium are mixed by a known method.

[0034] [Firing step] The mixture obtained by mixing is fired in an atmosphere of an inert gas or a non-oxidizing gas to produce β-type sialon phosphor particles.

[0035] The above β-sialon phosphor particles have a crystal represented by the general formula Si ６－ｚ Al ｚ O ｚ N ８－ｚ :Eu(0 < z ≤ 1.0). The phosphor containing β-sialon phosphor particles may be partially or entirely composed of the above crystal phase. For the general formula Si ６－ｚ Al ｚ O ｚ N ８－ｚ :Eu, the content of europium is preferably, for example, 0.1% by mass or more and 2.0% by mass or less.

[0036] The firing temperature in the firing step is preferably 1800 °C or higher and 2100 °C or lower, and more preferably 1850 °C or higher and 2050 °C or lower. By setting the firing temperature to be not less than the above lower limit value, the emission intensity can be improved. On the other hand, by setting the firing temperature to be not more than the above upper limit value, the thermal load can be reduced. The firing step may be carried out multiple times. Also, when performing the firing for the second time and later, a part of the raw material may be further added.

[0037] [Post-treatment step] The post-treatment step includes one or more treatments selected from crushing and pulverizing treatment, classification treatment, annealing treatment, and acid treatment, and these treatments may be in any order.

[0038] (Annealing treatment) The obtained β-sialon phosphor may be annealed in a gas atmosphere. The gas introduction temperature during the annealing treatment is preferably 300 °C or higher and 950 °C or lower, more preferably 400 °C or higher and 800 °C or lower, and still more preferably 450 °C or higher and 650 °C or lower. By setting the gas introduction temperature during annealing to be not less than the above lower limit value, crystal surface reconstruction is promoted and good emission intensity is maintained. On the other hand, by setting the gas introduction temperature during annealing to be not more than the above upper limit value, fine irregularities can be imparted to the surface during the crystal surface reconstruction process. As a result, light reflection is suppressed and it becomes easier to improve the luminance. Also, the maximum temperature of the annealing treatment is preferably 1200 °C or higher and 1700 °C or lower, more preferably 1300 °C or higher and 1600 °C or lower, and still more preferably 1400 °C or higher and 1500 °C or lower.

[0039] The atmosphere gas during annealing is selected from any one of noble gases of Group 18 elements in the periodic table such as argon gas, inert gases such as nitrogen gas, hydrogen gas, or a mixed gas of hydrogen gas and argon gas.

[0040] The annealing treatment is exerted under a wide range of atmospheric pressures from reduced pressure to increased pressure, but by setting it to 1.0 kPa or more, decomposition of the β-type sialon phosphor can be suppressed. On the other hand, from the point of expanding other conditions necessary for expressing the annealing effect by pressurizing the atmosphere (lowering the temperature, shortening the time), the preferable atmospheric pressure is 10 MPa or less, and more preferably less than 1.0 MPa.

[0041] The annealing treatment time is preferably 1 hour or more and 24 hours or less, and more preferably 2 hours or more and 10 hours or less. Among these, when the atmosphere temperature during annealing is 1400 to 1500 °C, it is preferable to set it to 8 hours.

[0042] (Acid treatment) Further, an acid treatment may be applied by immersing the β-type sialon phosphor in an acid solution after the annealing treatment. Thereby, the characteristics of the phosphor can be further improved.

[0043] The acid treatment preferably includes immersing the β-type sialon phosphor in an acid solution, separating the β-type sialon phosphor and the acid with a filter or the like, and washing the separated β-type sialon phosphor with water. By the acid treatment, decomposition products of the β-type sialon phosphor crystals generated during the annealing treatment can be removed, and thereby the fluorescence characteristics are improved.

[0044] Examples of the acid used for the acid treatment include hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, or a simple substance or mixture of nitric acid, and a mixed acid composed of hydrofluoric acid and nitric acid suitable for removing decomposition products is preferable.

[0045] The acid concentration is preferably 5 to 100%, more preferably 10 to 50%, and even more preferably 20 to 30%. Setting the acid concentration above the lower limit makes it easier to impart fine depressions to some of the β-type Sialon phosphor particles. As a result, light reflection can be controlled to a high degree, and brightness can be increased while maintaining good luminescence intensity. On the other hand, setting the acid concentration below the upper limit allows for good brightness to be obtained while maintaining good internal quantum efficiency.

[0046] The temperature of the acid solution during acid treatment can be at room temperature, but to enhance the effect of the acid treatment, it is preferable to heat it to between 50°C and 90°C.

[0047] By the method described above, the β-type sialon phosphor particles of this embodiment can be obtained.

[0048] Furthermore, known processes may be added as needed in this embodiment. For example, post-processing such as crushing, pulverization, drying, sieving, and classification may be performed. Processes to adjust particle size, such as sieving and classification, may be performed at any point after the calcination process, after the annealing process, or after the acid treatment.

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

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

[0051] The wavelength converter of this embodiment converts light irradiated from a light-emitting element to emit light, and has the above-mentioned β-type sialon phosphor particles. The wavelength converter may consist only of β-type sialon phosphor particles, or it may include a matrix in which β-type sialon phosphor particles are dispersed. Known materials can be used as the matrix, but examples include glass, resin, and inorganic materials.

[0052] The wavelength converter described above is not particularly limited in shape and may be configured in a plate shape, or it 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 comprises a light-emitting member including a light-emitting source (light-emitting element) and the wavelength converter. By combining the light-emitting source and the wavelength converter, light with high emission intensity can be emitted.

[0055] An example of a manufacturing method for the light-emitting device of this embodiment includes a step of mounting a wavelength conversion member obtained by a method for manufacturing a wavelength conversion member onto the light-emitting surface of a light-emitting 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 generate light with wavelengths ranging from near-ultraviolet to blue light, specifically from 300 nm to 500 nm. 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 above wavelength converter may contain the above β-type sialon phosphor particles, but may also contain other phosphors. Other phosphors may include, for example, α-type sialon phosphors, KSF phosphors, CASN phosphors, SCASN phosphors, and YAG phosphors. These phosphors may be used individually or in combination of two or more.

[0058] In the case of a light-emitting device using the above-mentioned β-type Sialon phosphor particles, by irradiating with near-ultraviolet light or visible light containing wavelengths between 300 nm and 500 nm as the excitation source, it exhibits green emission characteristics with a peak in wavelengths between 520 nm and 560 nm. Therefore, by combining a near-ultraviolet LED chip or a blue LED chip with β-type Sialon phosphor and one or more red, blue, yellow, or orange phosphors as the light-emitting source, white light can be produced.

[0059] For example, by combining a β-type sialon phosphor that exhibits green light with a KSF-type phosphor that exhibits red light, it can be suitably used in LEDs for backlights suitable for high color rendering TVs and the like.

[0060] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted.

[0061] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to the descriptions of these examples.

[0062] 1. Preparation of β-type Sialon phosphor particles <Comparative Example 1> (1) 95.58% by mass of α-type silicon nitride (SN-E10 grade, oxygen content 1.0% by mass, manufactured by Ube Industries, Ltd.), 2.89% by mass of aluminum nitride (E grade, oxygen content 0.8% by mass, manufactured by Tokuyama Corporation), 0.93% by mass of aluminum oxide (TM-DAR grade, manufactured by Daimyo Chemical Co., Ltd.), and 0.60% by mass of europium oxide (RU grade, manufactured by Shin-Etsu Chemical Co., Ltd.) were weighed. The obtained mixture was passed through a sieve with a mesh size of 250 μm to remove aggregates and obtain a raw material composition. Aggregates that did not pass through the sieve were crushed and the particle size was adjusted so that it could 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 (manufactured by Denka Co., Ltd., a molded product mainly composed of boron nitride (product name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). Then, this container was placed in an electric furnace equipped with a carbon heater and heated to 2000°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG), and heated at a heating temperature of 2000°C for 10 hours (calcination process). After heating, the loosely aggregated mass of the sample in the container was taken into a mortar and crushed. After crushing, it was passed through a sieve with a mesh size of 250 μm to obtain a powdered first calcined body.

[0064] (3) Next, the first calcined body was filled into a cylindrical boron nitride container, and this container was placed in an electric furnace equipped with a carbon heater. Heating was started from a vacuum state, argon gas was introduced at 1000°C, and the temperature was raised to 1450°C under an argon gas atmosphere (pressure: 0.025 MPaG), and heating was carried out at a heating temperature of 1450°C for 5 hours (annealing process). After heating, the loosely aggregated mass of particles in the container was crushed in a mortar and pestle, and powder was obtained by passing it through a 250 μm sieve.

[0065] (4) Next, the powder obtained in (3) above was added to a solution of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) diluted to an acid concentration of 2.5% by volume. The solution was then acid-treated at 75°C for 30 minutes while stirring. After the acid treatment, stirring was stopped and the powder was allowed to settle, and the supernatant and the fine powder purified by the acid treatment were removed. Distilled water was then added and stirred again. The process of stopping stirring, allowing the powder to settle, and removing the supernatant and fine powder was repeated until the solution became neutral. The resulting precipitate was filtered, dried, and passed through a sieve with a mesh size of 250 μm to obtain the europium-activated β-type sialon phosphor particles of Comparative Example 1.

[0066] <Example 1> In Example 1, β-type sialon phosphor particles were prepared under the same conditions as in Comparative Example 1, except that the argon gas introduction temperature in (3) of Comparative Example 1 was changed from 1000°C to 600°C, and the acid concentration in (4) was changed from 2.5% by volume to 25%.

[0067] <Example 2> Example 2 was prepared under the same conditions as Example 1, except that the mixing ratio of the raw materials was changed to 93.29% by mass of α-type silicon nitride powder, 2.82% by mass of aluminum nitride powder, 0.91% by mass of aluminum oxide powder, 0.98% by mass of europium oxide powder, and 2.00% by mass of β-type sialon phosphor particles as a nucleating agent.

[0068] <Example 3> Example 3 was prepared under the same conditions as Example 1, except that the argon gas introduction temperature was changed from 600°C to 800°C.

[0069] 2. Evaluation The following characteristics and evaluation items were evaluated for the β-type Sialon phosphor particles of each example and comparative example.

[0070] <SEM Observation> The surface of β-type Sialon phosphor particles was observed using a scanning electron microscope (SEM) at a magnification of 50,000x under the following conditions, and the presence or absence of the following was evaluated: "high-density striped regions where the stripe density of the striped pattern is 15 stripes / μm or more in a 2.5 μm square area", "linear regions where the stripe density of the striped pattern is 15 stripes / μm or more, and the striped pattern consists of linear stripes with a length of 1 μm or more", "curved regions where the stripe density of the striped pattern is 15 stripes / μm or more in a 2.5 μm square area, and the striped pattern consists of curved stripes", "medium-density striped regions where the stripe density of the striped pattern is 5 stripes / μm or more and less than 15 stripes / μm in a 2.5 μm square area", and "smooth regions of 2.5 μm square or larger". Observed regions were marked with "○", and those not observed were marked with "×", as shown in Table 1. (Conditions) As a pretreatment, the sample was fixed with carbon paste and observed using a Hitachi High-Tech SU8000 field emission scanning electron microscope at an acceleration voltage of 1 kV and an observation magnification of 50,000x.

[0071] Figure 2 shows a scanning electron microscope (SEM) image of the β-type sialon phosphor particles of Example 1, Figure 3 shows a scanning electron microscope (SEM) image of the β-type sialon phosphor particles of Example 2, Figure 4 shows a scanning electron microscope (SEM) image of the β-type sialon phosphor particles of Example 3, and Figure 5 shows a scanning electron microscope (SEM) image of the β-type sialon phosphor particles of Comparative Example 1.

[0072] <50% Cumulative Diameter (D50)> The particle size distribution of each phosphor powder was measured in accordance with the particle size distribution measurement method by laser diffraction and scattering described in JIS R 1629:1997 "Method for Measuring Particle Size Distribution of Fine Ceramics Raw Materials by Laser Diffraction and Scattering". Specifically, first, 0.03 g of the phosphor powder to be measured was added to 100 mL of ion-exchanged water containing 0.05 mass% sodium hexametaphosphate, and the mixture was dispersed for 3 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., product name "Ultrasonic Homogenizer US-150E", Amplitude: 100%, oscillation frequency: 19.5 kHz, tip size: φ20, amplitude: 32 ± 2 μm) to prepare the measurement sample. Subsequently, particle size distribution was measured using a particle size distribution analyzer (Microtrac MT3300EX II, manufactured by Microtrac Bell Co., Ltd.). From the obtained particle size distribution, the particle size D50 corresponding to 50% of the cumulative fraction based on volume was determined. The results are shown in Table 1.

[0073] <Luminescence Characteristics> [Manufacturing of Light-Emitting Devices] The β-type sialon phosphor particles of the examples and comparative examples were added together with KSF phosphor (KR-2K01, emission peak wavelength of 631 nm when excited with a wavelength of 455 nm, manufactured by Denka Co., Ltd.) to a curable silicone resin (KER-6150, manufactured by Shin-Etsu Chemical Co., Ltd.), degassed and kneaded, then potted into a surface-mount type package to which a blue light-emitting semiconductor element with a peak wavelength of 450 nm was bonded, and then heat-cured to produce a white LED. The addition ratio of KSF phosphor to β-type sialon phosphor particles was adjusted so that the chromaticity coordinates (x, y) of the white LED were (0.28, 0.27) when power was applied and light was emitted. [Brightness: Relative Total Luminous Flux] Ten white LEDs containing β-type Sialon phosphor particles from the examples and comparative examples were selected, particularly those with a chromaticity x of 0.275 to 0.284 and a chromaticity y of 0.265 to 0.274. Each white LED was energized to emit light, and the total luminous flux was determined using a total luminous flux measuring device combining a spectrophotometer (MCPD-9800, manufactured by Otsuka Electronics Co., Ltd.) with a 300 mm diameter integrating hemisphere (manufactured by Otsuka Electronics Co., Ltd.). The average value of these measurements was taken as the representative value of the total luminous flux. Table 1 shows the relative values ​​as relative total luminous flux (%), with the total luminous flux of Comparative Example 1 set to 100%. A larger relative total luminous flux indicates higher brightness as a light-emitting element.

[0074]

[0075] This application claims priority based on Japanese Patent Application No. 2024-193569, filed on 5 November 2024, and incorporates all of its disclosures herein.

Claims

1. Beta-type SiAlON phosphor particles having a particle size (D50) of 50% of the cumulative volume frequency of the particle size distribution measured by wet laser diffraction particle size distribution method, where the particle size is between 5 and 150 μm, and satisfying the following condition i: (Condition i) When the surface of the beta-type SiAlON phosphor particles is observed at a magnification of 50,000x using a scanning electron microscope (SEM), a striped pattern can be confirmed.

2. Beta-type sialon phosphor particles according to claim 1, wherein, under condition i, the striped pattern has high-density striped regions where the stripe density of the striped pattern in a 2.5 μm square area is 15 stripes / μm or more.

3. Beta-type sialon phosphor particles according to claim 1 or 2, wherein, in condition i, the striped pattern has a stripe density of 15 stripes / μm or more, and the striped pattern has linear regions composed of linear stripes with a length of 1 μm or more.

4. Beta-type sialon phosphor particles according to claim 1 or 2, wherein, in condition i, the striped pattern has a stripe density of 15 stripes / μm or more in a 2.5 μm square area, and the striped pattern has a curved region composed of curved stripes.

5. Beta-type sialon phosphor particles according to claim 1 or 2, wherein, under condition i, the striped pattern has a medium-density striped region where the stripe density of the striped pattern in a 2.5 μm square area is 5 stripes / μm or more and less than 15 stripes / μm.

6. Beta-type sialon phosphor particles according to claim 1 or 2, further satisfying condition ii. (Condition ii) When the surface of the beta-type sialon phosphor particles is observed with a scanning electron microscope (SEM) at a magnification of 50,000, no smooth region of 2.5 μm square or larger is observed.

7. A β-type sialon phosphor powder comprising β-type sialon phosphor particles according to claim 1 or 2.

8. A light-emitting device comprising a light-emitting light source and a wavelength conversion member, wherein the wavelength conversion member comprises phosphor powder, and the phosphor powder comprises the β-type sialon phosphor powder described in claim 7.

9. A light-emitting device according to claim 8, wherein the light-emitting light source includes an LED chip that generates light with a wavelength of 300 nm or more and 500 nm or less.

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