Phosphorescent ceramics, light-emitting devices, and methods for manufacturing the same.

Abstract

To provide a phosphor ceramic with improved heat conductivity.SOLUTION: A method for manufacturing a phosphor ceramic includes preparing a precursor including aluminum nitride as the base material, and bringing the precursor into contact with a gas containing manganese to form the phosphor ceramic.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to phosphorescent ceramics, light-emitting devices, and methods for manufacturing the same. [Background technology]

[0002] Nitride phosphors are attracting attention as materials with excellent physical and chemical properties. Patent Document 1 discloses a method for manufacturing a luminescent sintered body, which involves mixing aluminum nitride with a compound containing a sintering aid and an element that acts as a luminescent center, and then firing the mixture. Non-Patent Document 1 discloses a phosphor powder obtained by firing a mixed powder of aluminum nitride and manganese carbonate, in which divalent manganese is activated in the aluminum nitride. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-open No. 62-167260 [Non-patent literature]

[0004] [Non-Patent Document 1] Xiao-Jun Wang et al., Dalton Transactions, 2014, 43, 6120-6127 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] There is a need for phosphorescent ceramics with improved thermal conductivity.

[0006] One aspect of this disclosure aims to provide phosphor ceramics with high thermal conductivity and methods for manufacturing them. [Means for solving the problem]

[0007] The first aspect includes preparing a precursor whose base material is aluminum nitride, and bringing the precursor into contact with a gas containing manganese to obtain a phosphor ceramic, and is a method for manufacturing a phosphor ceramic.

[0008] The second aspect includes preparing the phosphor ceramic, preparing an excitation light source, and arranging the phosphor ceramic at a position irradiated with light emitted by the excitation light source, and is a method for manufacturing a light-emitting device.

[0009] The third aspect is a phosphor ceramic containing aluminum nitride, yttrium, and manganese, and having an oxygen content of less than 2.4% by mass.

[0010] The fourth aspect is a light-emitting device including an excitation light source and the phosphor ceramic arranged at a position irradiated with light emitted by the excitation light source.

Effect of the Invention

[0011] According to one aspect of the present disclosure, it is possible to provide a phosphor ceramic having high thermal conductivity and a method for manufacturing the same.

Brief Description of the Drawings

[0012] [Figure 1] It is a flowchart showing an example of a method for manufacturing a phosphor ceramic. [Figure 2] It is a flowchart showing an example of a method for manufacturing a phosphor ceramic including a method for manufacturing a precursor. [Figure 3] It is a flowchart showing another example of a method for manufacturing a phosphor ceramic including a method for manufacturing a precursor. [Figure 4] It is a cross-sectional view showing an example of a light-emitting device including a phosphor ceramic. [Figure 5] It is an X-ray diffraction pattern of the phosphor ceramic according to Example 11 and AlN, MnO2, and Y2O3 registered in the inorganic crystal structure database. [Figure 6]This is the excitation spectrum obtained from the phosphor ceramic according to Example 11. [Figure 7] This is the emission spectrum obtained from the phosphor ceramic according to Example 11. [Figure 8A] This is a cross-sectional SEM image of the phosphor ceramic according to Example 1. [Figure 8B] This is a cross-sectional SEM image of the phosphor ceramic according to Example 11. [Modes for carrying out the invention]

[0013] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. In addition, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. Embodiments of the present invention will now be described in detail. However, the embodiments shown below are illustrative examples of phosphor ceramics and methods for manufacturing the same to embody the technical concept of the present invention, and the present invention is not limited to the phosphor ceramics and methods for manufacturing the same shown below.

[0014] In this specification, ceramics refers to an aggregate of materials formed by bonding multiple powders together through sintering. Therefore, materials that maintain their raw powder state, such as aluminum nitride powder, are not included in the definition of ceramics. In this specification, ppm represents parts per million mass, calculated by (mass) / (mass).

[0015] The following describes the phosphor ceramics, methods for manufacturing the phosphor ceramics, light-emitting devices, and methods for manufacturing the light-emitting devices related to this disclosure, based on embodiments. However, the embodiments shown below are illustrative examples for realizing the technical concept of the present invention, and the present invention is not limited to the forms shown below.

[0016] <Phosphorescent Ceramics> The phosphor ceramics of this embodiment contain aluminum nitride, yttrium, and manganese. The oxygen content of the phosphor ceramics of this embodiment is less than 2.4% by mass. As will be described later, aluminum nitride is the base material of the phosphor ceramics. Therefore, the phosphor ceramics can also be called aluminum nitride phosphor ceramics.

[0017] According to this embodiment, it is possible to provide phosphor ceramics with high thermal conductivity.

[0018] (aluminum nitride) The phosphorescent ceramics contain aluminum nitride. Aluminum nitride is the base material of the phosphorescent ceramics. In this specification, "base material" refers to a material that accounts for, for example, 90% or more and less than 100% by volume, preferably 95% or more and 99.9% or less of the total amount of the material in question. Here, aluminum nitride accounts for, for example, 90% or more and 99.9% or less by volume, preferably 95% or more and 99.9% or less of the total amount of the phosphorescent ceramics. The aluminum nitride base material forms an aluminum nitride crystalline phase. Hereinafter, the aluminum nitride crystalline phase will also be simply referred to as the crystalline phase. The crystalline phase is an aggregate of multiple aluminum nitride particles bonded together. Hereinafter, aluminum nitride particles will also be simply referred to as AlN particles. The AlN particles constituting the crystalline phase include, for example, those with a size of 8 μm or more and 30 μm or less. In addition, the AlN particles constituting the crystalline phase may include, for example, those with a size of 10 μm or more and 20 μm or less. A crystalline phase containing AlN particles of this size can be included in phosphor ceramics as a highly pure crystalline phase, for example, when sufficient oxygen contained in the phosphor ceramics has been removed. Including AlN particles of this size can improve the thermal conductivity of phosphor ceramics. Note that the size of the AlN particles is not limited to the above range. When a crystalline phase is formed using high-purity AlN particles, the thermal conductivity of phosphor ceramics can be improved even if the size of the AlN particles is relatively small. For example, the size of the AlN particles may be between 1 μm and 8 μm. The size of the AlN particles can be determined, for example, by examining the size of the AlN particles in an arbitrary region of a cross-sectional SEM image observed at 1000x magnification. An arbitrary region is, for example, a region of 127 μm × 88 μm. A straight line can be drawn on the obtained image, and the length from grain boundary to grain boundary of the AlN particles that overlap this line can be measured. The average size of the AlN particles determined by the above method may be, for example, between 1 μm and 30 μm.

[0019] (manganese) The phosphorescent ceramics contain manganese. The manganese content in the phosphorescent ceramics is, for example, 50 ppm or less. This allows the phosphorescent ceramics to function as a phosphor by doping the crystalline phase with manganese. That is, manganese-doped aluminum nitride can emit light when it receives light of a predetermined wavelength emitted from an excitation light source. The manganese content in the phosphorescent ceramics is preferably 30 ppm or less, more preferably 10 ppm or less, and even more preferably 5 ppm or less. This allows the phosphorescent ceramics to achieve both light emission and high thermal conductivity. The manganese content in the phosphorescent ceramics may also be, for example, 1 ppm or more. The detailed amount of manganese (Mn) in the phosphorescent ceramics can be estimated by trace analysis using a high-frequency inductively coupled plasma (ICP) emission spectrometer (for example, the Avio500 from PerkinElmer).

[0020] (yttrium) The phosphorescent ceramic may contain at least one rare earth element. For example, the phosphorescent ceramic may contain yttrium. The yttrium content may be, for example, 5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less. When the yttrium content is, for example, 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less, the number of grain boundary phases connecting the crystalline phases is reduced, improving the light transmittance of the phosphorescent ceramic. In addition, since the distance between the crystalline phases can be shortened, the thermal conductivity of the phosphorescent ceramic can be improved. Note that when phosphorescent ceramics are made using a sintering aid, the rare earth elements contained in the sintering aid may be contained in the phosphorescent ceramic.

[0021] (oxygen) Phosphorescent ceramics may contain oxygen. The oxygen content in phosphorescent ceramics may be, for example, less than 2.4% by mass. This can improve the thermal conductivity of the phosphorescent ceramics. Preferably, the oxygen content in phosphorescent ceramics may be 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less. This can reduce the grain boundary phase, thereby improving the light transmittance in the phosphorescent ceramics. It can also shorten the distance between crystalline phases, thereby improving the thermal conductivity of the phosphorescent ceramics. The oxygen content in phosphorescent ceramics can be measured using an oxygen / nitrogen analyzer (for example, EMGA-820, manufactured by Horiba, Ltd.). Note that the oxygen content in phosphorescent ceramics may be below the detection limit of the oxygen / nitrogen analyzer and may not be detected.

[0022] (Other metallic elements) Phosphorescent ceramics may contain aluminum, yttrium, and other metallic elements except manganese. The content of aluminum, yttrium, and other metallic elements is, for example, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less. By having a lower content of aluminum, yttrium, and other metallic elements than predetermined levels, discoloration of the phosphorescent ceramics, a decrease in thermal conductivity, and unwanted light absorption can be reduced.

[0023] (grain boundary phase) Phosphorescent ceramics may contain grain boundary phases that connect crystalline phases. These grain boundary phases may contain yttrium-containing oxides. As mentioned above, the grain boundary phases can be reduced by decreasing the yttrium and oxygen content. The yttrium content can be determined by cutting the aluminum nitride phosphorescent ceramic so that its cross-section is exposed, and then analyzing a specific point on the cross-section, for example, using an electron probe microanalyzer (EPMA), or a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). EPMA can be measured using a field emission electron probe microanalyzer (e.g., model JXA-8500F, manufactured by JEOL Ltd.). SEM and EDX can be measured using a SEM-EDX instrument (e.g., model SU8230, manufactured by Shimadzu Corporation, and a silicon drift detector, manufactured by Horiba, Ltd.). For example, in any cross-section of an aluminum nitride phosphor ceramic, it is possible to select any three to five locations in the grain boundary phase, detect the yttrium content in the grain boundary phase at the selected locations, and measure the average value as the yttrium content present in the grain boundary phase.

[0024] (Thermal conductivity) Phosphor ceramics have excellent heat dissipation properties. The thermal conductivity of phosphor ceramics is relatively high because the base material is aluminum nitride. The thermal conductivity of phosphor ceramics is, for example, 150 W / (m·K) to 260 W / (m·K), preferably 200 W / (m·K) to 260 W / (m·K), more preferably 210 W / (m·K) to 260 W / (m·K), and particularly preferably 220 W / (m·K) to 260 W / (m·K). Thermal conductivity is equal to the thermal diffusivity α(m 2 (J / (kg·K)), specific heat capacity Cp (J / (kg·K)), and apparent density (kg / m³) 3 It can be determined by the product of ( ). In this specification, the value of the specific heat capacity Cp used is 0.72 J / (kg·K), which is the specific heat capacity of aluminum nitride.

[0025] (Thermal diffusivity) In the phosphor ceramics, the thermal diffusivity measured by the laser flash method at 25°C is, for example, 60 mm 2 / s or more and 136.3 mm 2 / s or less. 136.3 mm 2 / s represents the thermal diffusivity of single crystal aluminum nitride. The thermal diffusivity of the phosphor ceramics may be 68 mm 2 / s or more and 136.3 mm 2 / s or less, preferably 80 mm 2 / s or more and 136.3 mm 2 / s or less, 85 m 2 / s or more and 136.3 mm 2 / s or less, 90 mm 2 / s or more and 130 mm 2 / s or less, 95 mm 2 / s or more and 125 mm 2 / s or less, or 100 mm 2 / s or more and 120 mm 2 / s or less. The laser flash method can be measured at 25°C for a sample of 10 mm in length × 10 mm in width × 2 mm in thickness using, for example, a laser flash analyzer (e.g., LFA447 or LFA467, manufactured by NETZSCH).

[0026] (Apparent density) The apparent density of the phosphor ceramics is, for example, 2.5 g / cm 3 or more and 3.5 g / cm 3 or less, 3.0 g / cm 3 or more and 3.5 g / cm 3 or less, 3.1 g / cm 3 or more and 3.5 g / cm 3 or less, 3.2 g / cm 3 or more and 3.5 g / cm 3 or less. 3.5 g / cm 3 represents the apparent density of the phosphor ceramics, which represents the theoretical density. The apparent density can be calculated by dividing the mass of the phosphor ceramics by the volume measured by the Archimedes method.

[0027] (Excitation spectrum) The excitation spectrum of the phosphor ceramic may have an intensity peak in the wavelength range of 230 nm to 250 nm. Furthermore, the excitation spectrum may have a shoulder structure in the wavelength range of 260 nm to 300 nm. Additionally, the absolute value of the rate of change of spectral intensity in the wavelength range of 260 nm to 280 nm may be smaller than the absolute value of the rate of change of spectral intensity in the wavelength range of 240 nm to 260 nm.

[0028] (Emission spectrum) Phosphorescent ceramics emit light upon excitation. The emission spectrum of phosphorescent ceramics has an intensity peak in the range of 590 nm to 620 nm. The half-width at half maximum (FWHM) of the emission spectrum is 50 nm or less, preferably 40 nm or less, and more preferably 25 nm or less. Furthermore, phosphorescent ceramics have afterglow properties, and can produce afterglow for several tens of seconds to about one minute even after the excitation light irradiation has ended. In addition, the emission intensity of phosphorescent ceramics can increase when exposed to excitation light for a long period of time, for example.

[0029] The above describes phosphor ceramics, but phosphor ceramics may also take the following forms, for example. Parts that overlap in content will be omitted. The phosphor ceramic is a phosphor ceramic containing aluminum nitride and manganese, wherein the manganese content is 1 ppm to 50 ppm, and the thermal diffusivity of the phosphor ceramic, measured by the laser flash method at 25°C, is 60 mm². 2 The thermal conductivity is 2 / s or higher. This makes it possible to obtain phosphorescent ceramics with high thermal conductivity.

[0030] <Manufacturing method> A method for producing phosphor ceramics involves preparing a precursor whose base material is aluminum nitride, and contacting the precursor with a gas containing manganese to obtain phosphor ceramics. This includes. Figure 1 is a flowchart of an example of a method for manufacturing phosphor ceramics. The method for manufacturing phosphor ceramics includes a step S1 of preparing a precursor and a step S2 of obtaining phosphor ceramics.

[0031] According to the method for producing phosphor ceramics of this embodiment, phosphor ceramics with high thermal conductivity can be obtained.

[0032] (Step S1: Preparing the precursor) This step involves preparing a precursor for phosphorescent ceramics. The precursor is a molded body or a sintered body containing aluminum nitride. The precursor uses aluminum nitride as its base material. The aluminum nitride base material accounts for, for example, 90% or more and less than 100% by volume of the entire precursor, preferably 95% or more and 99.9% or less. The precursor may be a commercially available product or may be manufactured by the method described below.

[0033] The method for manufacturing the precursor will be described below. The precursor is either a molded body containing aluminum nitride or a sintered body containing aluminum nitride. Figure 2 is a flowchart showing an example of a method for manufacturing phosphor ceramics, including the method for manufacturing the precursor, when the precursor is a molded body containing aluminum nitride. Figure 3 is a flowchart showing an example of a method for manufacturing phosphor ceramics, including the method for manufacturing the precursor, when the precursor is a sintered body containing aluminum nitride. Hereinafter, the molded body containing aluminum nitride will be simply referred to as the molded body, and the sintered body containing aluminum nitride will be simply referred to as the sintered body.

[0034] Referring to Figures 2 and 3, an example of a method for manufacturing a precursor when the precursor is a molded body or when the precursor is a sintered body will be described. When the precursor is a molded body, the method for manufacturing the molded body includes a step S10a for preparing the raw material mixture and a step S10d for forming the granules. It may optionally include one or all of the following: a step S10b for preparing the kneaded material, a step S10c for granulating the kneaded material, or a step S10e for heating and degreasing the molded body. Furthermore, when the precursor is a sintered body, it further includes a step S10f for first firing of the degreased body.

[0035] (Step S10a: Preparation of raw material mixture) In the precursor preparation process, aluminum nitride powder and, if necessary, a sintering aid containing rare earth elements are prepared. Hereafter, aluminum nitride powder will also be simply referred to as AlN powder.

[0036] (Aluminum nitride powder) The proportion of AlN powder in the raw material mixture is 90% by mass or more and 99.9% by mass or less based on 100% by mass of the raw material mixture. Therefore, the base material of the precursor produced is aluminum nitride. Alternatively, the proportion of AlN powder in the raw material mixture may be 93% by mass or more and 99.7% by mass or less, 95% by mass or more and 99.6% by mass or less, or 95% by mass or more and 99.5% by mass or less based on 100% by mass of the raw material mixture.

[0037] The central particle size Da of the AlN powder may be within the range of 0.1 μm to 5 μm, 0.3 μm to 3 μm, or 0.5 μm to 1.5 μm. This allows for the production of a dense sintered body and phosphor ceramics with high thermal conductivity. The central particle size Da of the AlN powder refers to the particle size corresponding to 50% of the volume-based cumulative particle size distribution measured by the Coulter counter method. The particle size distribution can be measured using a particle size distribution analyzer (e.g., CMS, manufactured by Beckman Coulter, Inc.).

[0038] AlN powder may contain oxygen. The oxygen content in the AlN powder is preferably 2% by mass or less, and more preferably 1.5% by mass or less, relative to the total amount of AlN powder. This reduces point defects of Al in the lattice of the aluminum nitride crystalline phase that constitutes the base material of the phosphor ceramic, and reduces the amount of grain boundary phase made of oxide, making it possible to produce phosphor ceramics with high thermal conductivity.

[0039] It is preferable that the AlN powder does not contain any metal elements other than aluminum. The content of metal elements other than aluminum relative to the total amount of AlN powder may be, for example, 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less, or 0.01% by mass or less. This can reduce the discoloration of the resulting phosphor ceramics. It can also reduce the decrease in thermal conductivity. In particular, the content of metal elements other than aluminum relative to the total amount of AlN powder is preferably 100 ppm or less, and the iron content is especially preferably 20 ppm or less. This can reduce the black discoloration of the phosphor ceramics. The content of metal elements other than aluminum in the AlN powder can be measured by an inductively coupled plasma atomic emission spectrometry (ICP-AES) device.

[0040] The AlN powder may have a reflectance of 50% or more, or 70% or more, within the wavelength range of 400 nm to 700 nm. This increases the reflectance of the resulting phosphor ceramic, thereby increasing the emission intensity when excited by an excitation light source.

[0041] (Sintering aid) The raw material mixture may contain a sintering aid. The inclusion of a sintering aid allows for dense bonding of aluminum nitride crystals, resulting in a precursor with high thermal conductivity. Examples of sintering aids include compounds such as oxides and fluorides containing rare earth elements. Examples of rare earth-containing oxides include yttrium oxide, europium oxide, lanthanum oxide, cerium oxide, ytterbium oxide, praseodymium oxide, neodymium oxide, samarium oxide, gadolinium oxide, dysprosium oxide, and erbium oxide. The most preferred sintering aid is yttrium oxide. Yttrium oxide readily forms a liquid phase with oxygen contained in the AlN powder, making it easy to obtain a dense sintered body.

[0042] The content of the sintering aid in the raw material mixture may be 0.05% to 10% by mass, 0.1% to 7% by mass, or 0.1% to 5% by mass, based on 100% by mass of the raw material mixture. Furthermore, the raw material mixture may not contain any sintering aid.

[0043] The sintering aid is preferably in powder form. The central particle size De of the sintering aid may be 0.1 μm to 5 μm, 0.2 μm to 4 μm, or 0.3 μm to 3 μm. The central particle size De of the sintering aid refers to the particle size corresponding to 50% of the volume-based cumulative particle size distribution measured by the Coulter counter method. The central particle size De of the sintering aid is preferably in a particle size ratio De / Da of 0.1 to 20 with respect to the central particle size Da of the AlN powder. This makes it easier for the particles constituting the raw material mixture to disperse, making it easier to obtain a sintered body with high density. The particle size ratio De / Da of the central particle size De of the sintering aid to the central particle size Da of the AlN powder is more preferably in the range of 0.2 to 18, 0.3 to 15, or 0.5 to 10. This makes it less likely for the state after mixing with the AlN powder to become uneven.

[0044] A raw material mixture containing aluminum nitride and a sintering aid can be obtained by dry mixing or wet mixing. Dry mixing refers to mixing aluminum nitride and each compound in the absence of liquid. Wet mixing refers to mixing the raw materials in the presence of an organic solvent or water. Dry mixing is the preferred mixing method. In the case of dry mixing, the raw material mixture can contain both large and small particles of the sintering aid. Relatively large sintering aid particles are thought to easily generate localized liquid phases. These localized liquid phases are thought to facilitate the rearrangement of aluminum nitride particles, making it easier to form a dense sintered body. Also, since aluminum nitride is sensitive to moisture, dry mixing, which does not utilize moisture, is preferred. Furthermore, dry mixing simplifies the manufacturing process compared to wet mixing. Dry mixing can be performed using equipment such as super mixers, axial mixers, Henschel mixers, ribbon mixers, and rocking mixers. Wet mixing can be performed using equipment such as ball mills and media-stirring mills.

[0045] (Step S10b: Preparation of the mixed material) The process of preparing the precursor may include a step of preparing a compound by kneading the raw material mixture and an organic substance. Examples of organic substances include those used as binders, lubricants, and plasticizers. The amount of organic substance in the compound should be sufficient to adequately mix the raw material mixture and the organic substance without affecting the properties of the resulting sintered body. The amount of organic substance in the compound may preferably be in the range of 10 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the raw material mixture. The compound may also further contain a coupling agent. The coupling agent is used to improve the dispersibility between the raw material mixture and the organic substance. Auxiliaries such as coupling agents may be added to the compound in an amount that does not affect the properties of the resulting sintered body.

[0046] Examples of organic materials used as binders include at least one thermoplastic resin selected from the group consisting of low-density polyethylene, medium-density polyethylene, high-density polyethylene, low molecular weight polyethylene, ethylene vinyl acetate copolymer, ethylene acrylate copolymer, polypropylene, atactic polypropylene, polystyrene, polyacetal, polyamide, and methacrylic resin. In addition to these thermoplastic resins, waxes such as paraffin wax and microcrystalline wax can also be used as binders. One binder may be used, or two or more may be used in combination.

[0047] Examples of organic substances used as lubricants include hydrocarbon-based lubricants such as liquid paraffin and paraffin wax, and fatty acid-based lubricants such as stearic acid and lauric acid. These lubricants may be used individually or in combination of two or more.

[0048] Examples of organic substances used as plasticizers include phthalates, adipicates, and trimelliticates. One type of plasticizer may be used, or two or more types may be used in combination.

[0049] (Process S10c for granulating the compounded material) The process of preparing the precursor may include a granulation step in which the compound is granulated. The compound may be granulated into granular or pelletized form before forming the molded body. The granular or pelletized compound can be obtained using known equipment such as a crusher, extruder, or pelletizer.

[0050] (Process S10d for forming granules) The process of preparing the precursor may include a step of molding a raw material mixture, a mixture of raw material and organic matter, or granules obtained by granulating the mixture. This yields a molded body. Methods for obtaining the molded body include injection molding, press molding using a die, cold isostatic pressing, extrusion molding, doctor blade method, and casting. Injection molding is preferred for obtaining the molded body. A molded body of a desired shape can be formed. The shape of the molded body in plan view may be, for example, a circle, an ellipse, a rectangle, a square, or other polygon, or a composite shape combining multiple shapes. The molded body may also have recesses and protrusions.

[0051] (Step S10e: Heating and degreasing the molded body) The process of preparing the precursor may include a step of heating and degreasing the molded body. Degreasing reduces the likelihood of the sintered body cracking due to residual carbon in the compound, thereby increasing the yield. It also reduces oxidation of the sintered body. Furthermore, depending on the type of organic matter, rapid heat generation may occur within the above temperature range, but such rapid temperature increases can be suppressed by heating in a nitrogen atmosphere. This suppresses the deterioration of the firing furnace. When heating and degreasing the molded body, it is preferable to heat in a nitrogen atmosphere, for example, in a range of 400°C to 700°C. In this specification, a nitrogen atmosphere refers to a state where the amount of nitrogen is equal to or greater than the volume percent of nitrogen contained in the atmosphere. The nitrogen in the nitrogen atmosphere should be 80 volume percent or more, preferably 90 volume percent or more, more preferably 99 volume percent or more, and even more preferably 99.9 volume percent or more. The oxygen content in the nitrogen atmosphere is 0.01 volume percent to 20 volume percent, and may be 0.1 volume percent to 10 volume percent. The atmospheric pressure for heating is, for example, atmospheric pressure. The process may also be carried out under a pressurized or reduced pressure environment. Furthermore, known methods can be used for degreasing. The carbon content in the molded body obtained by degreasing the molded compound is preferably, for example, 1000 ppm or less, and more preferably 500 ppm or less. The carbon content of the degreased molded body can be measured, for example, by non-dispersive infrared absorption spectroscopy. The degreasing time during heating should be sufficient to degrease the organic matter in the molded body so that its carbon content becomes 1000 ppm or less. Specifically, the heating time for degreasing (the time the maximum temperature is maintained) is preferably 0.1 hours or more and within 50 hours, and is appropriately adjusted according to the shape of the molded body being degreased.

[0052] (Step S10f: First calcination of the degreased body) The precursor is preferably a sintered body whose base material is aluminum nitride. This is because the thermal conductivity of a sintered body is higher than that of a molded body. When the precursor is a sintered body, the process may include a step of firing a degreased body to obtain a sintered body, as shown in Figure 3. Alternatively, the process may include a step of firing a molded body to obtain a sintered body. In this specification, firing a molded body or a degreased body to obtain a sintered body is also referred to as the first firing. The temperature during the first firing is also referred to as the first firing temperature. The atmosphere during the first firing is also referred to as the first firing atmosphere.

[0053] The first firing temperature is preferably in the range of 1700°C to 2050°C. This allows the aluminum nitride particles to bond tightly together in the liquid phase formed between them, forming a crystalline phase and resulting in a sintered body with high thermal conductivity. The first firing temperature is preferably in the range of 1750°C to 2050°C, more preferably in the range of 1800°C to 2050°C, and even more preferably in the range of 1850°C to 2050°C. This further improves the thermal conductivity of the precursor.

[0054] The first firing atmosphere is preferably the aforementioned nitrogen atmosphere. By performing the first firing in a nitrogen atmosphere, the aluminum nitride is less likely to decompose, and a sintered body with high thermal conductivity can be obtained. In addition, to maintain a stable nitrogen atmosphere in the first firing atmosphere, a nitrogen-containing gas can be supplied continuously or intermittently.

[0055] The pressure in the first firing atmosphere is, for example, around atmospheric pressure (101.32 kPa), which is preferable. The gauge pressure is 50 kPa or less. Since the boundary can be reached relatively easily, productivity improves.

[0056] The first firing time should be any time required to obtain a dense sintered body. Specifically, the first firing time may preferably be between 0.5 hours and 100 hours. More preferably, the first firing time may be between 10 hours and 70 hours, and even more preferably between 20 hours and 45 hours. This allows for the removal of unwanted oxygen from the molded or degreased body, resulting in a denser sintered body.

[0057] For the first firing, it is preferable to use a carbon furnace, which uses carbon as an internal furnace material such as a heating element or insulating material, in order to reduce the amount of oxygen in the sintered body. A furnace other than a carbon furnace may be used as long as it can maintain the first firing temperature.

[0058] The setter and crucible on which the molded or degreased body is placed are preferably made of materials that do not deform or decompose at the first firing temperature. The material of the setter or crucible is preferably a nitride such as boron nitride or aluminum nitride. It is preferable to use a setter or crucible made of a material containing nitride with a purity of 95% by mass or higher.

[0059] The sintered body may further include a fragmentation step. The shape of the fragmented sintered body in plan view may be, for example, a circle, an ellipse, a rectangle, a square, or other polygon, and may include recesses or protrusions.

[0060] The first firing step may be carried out by methods other than those described above, such as hot isostatic pressing or discharge plasma sintering. Discharge plasma sintering is also called pulse current pressing. Dense precursors can also be obtained by these methods.

[0061] The sintered body containing aluminum nitride contains oxygen, preferably with an oxygen content of 0.3% by mass or less. This reduces the amount of grain boundary phase formed between aluminum nitride particles in the sintered body, thereby further improving the thermal conductivity. Since the grain boundary phase has lower thermal conductivity than aluminum nitride, reducing this phase improves the thermal conductivity of the sintered body containing aluminum nitride. Furthermore, even if an element that will become the luminescence center is doped into the precursor in the process of forming the phosphorescent ceramics described later, the phosphorescent ceramics can have relatively high thermal conductivity. Moreover, the oxygen content of the sintered body containing aluminum nitride is preferably greater than 0% by mass and 0.1% by mass or less, and more preferably greater than 0% by mass and 0.01% by mass or less. This further improves the thermal conductivity of the resulting sintered body and also allows it to be translucent. For example, if excitation light with a peak wavelength of 380 nm is irradiated onto one side of a sintered body with a thickness of 2 mm, excitation light with a peak wavelength of 380 nm can be extracted from the side opposite to the side irradiated with the excitation light. Similarly, light emitted from phosphorescent ceramics can be extracted from the side opposite to the side irradiated with excitation light. This is because the grain boundary phase is reduced, and light absorption by the grain boundary phase is suppressed. Since the energy gap of aluminum nitride is approximately 6.2 eV, sintered bodies containing aluminum nitride are transparent to light with a peak wavelength of approximately 200 nm or higher.

[0062] The oxygen content in the precursor can be measured using an oxygen / nitrogen analyzer after acid decomposition of the sintered body. The oxygen content of the sintered body may be below the detection limit of the oxygen / nitrogen analyzer.

[0063] The thermal conductivity of the sintered body can be, for example, 150 W / (m·K) or more and 270 W / (m·K) or less, preferably 200 W / (m·K) or more and 270 W / (m·K) or less, and more preferably 220 W / (m·K) or more and 270 W / (m·K) or less.

[0064] (Step S2 to obtain phosphorescent ceramics) A phosphorescent ceramic can be obtained by contacting a precursor with a manganese-containing gas. In the process of obtaining the phosphorescent ceramic, it is preferable to include firing the precursor in a manganese-containing atmosphere at a temperature in the range of 1600°C to 2000°C. This makes it easier for manganese to dope the aluminum nitride crystalline phase in the sintered body containing aluminum nitride, thereby obtaining a phosphorescent ceramic. In this specification, the firing in the process of obtaining the phosphorescent ceramic is also referred to as the second firing. The firing temperature in the process of obtaining the phosphorescent ceramic is also referred to as the second firing temperature. The atmosphere of firing in the process of obtaining the phosphorescent ceramic is also referred to as the second firing atmosphere.

[0065] In the process of obtaining phosphor ceramics, it is preferable to perform a second firing at a temperature of 1600°C to 2000°C on a precursor and a manganese-containing compound arranged so as not to be in direct contact with the precursor. A manganese-containing gas is obtained from the manganese-containing compound, and this gas comes into contact with the precursor, doping the precursor with manganese. As a result, phosphor ceramics that emit light upon excitation light can be obtained. In addition, during the second firing process, the precursor generates a liquid phase and forms a dense sintered body. As a result, phosphor ceramics with high thermal conductivity can be obtained.

[0066] The second firing temperature may be in the range of 1600°C to 2000°C. Preferably, the second firing temperature may be 1700°C to 2000°C, 1750°C to 1950°C, or 1750°C to 1900°C. This makes it possible to increase the luminescence intensity while maintaining thermal conductivity.

[0067] The second firing atmosphere is preferably a nitrogen atmosphere. The oxygen content in the nitrogen atmosphere is 0.01% to 20% by volume, or 0.1% to 10% by volume. Alternatively, the atmosphere during the second firing may be an argon (Ar) atmosphere.

[0068] The second firing may be carried out, for example, at atmospheric pressure or in a pressurized environment. When the second firing is carried out in a pressurized environment, the atmospheric pressure for the second firing is preferably in the range of 0.01 MPa to 0.5 MPa in gauge pressure, but may also be in the range of 0.01 MPa to 0.1 MPa in gauge pressure, or in the range of 0.01 MPa to 0.08 MPa in gauge pressure.

[0069] The duration of the second firing should be set as appropriate, as long as it is sufficient time for manganese to dopage the phosphorescent ceramics. For example, it may be between 0.1 hours and 20 hours, or between 0.5 hours and 10 hours.

[0070] The manganese-containing compound may be one or more selected from the group consisting of oxides, nitrides, hydroxides, halides, and carbonates. Examples of manganese-containing compounds include manganese oxide (MnO, MnO2, or Mn2O3), manganese(II) fluoride (MnF2), and manganese carbonate (MnCO3). Manganese oxide is preferred as the manganese-containing compound because it is stable at room temperature or in the atmosphere.

[0071] In the process of obtaining phosphorescent ceramics, the manganese-containing gas is preferably a manganese-containing gas obtained by reducing manganese oxide. Methods for reducing manganese oxide include, for example, placing a precursor and manganese oxide in a carbon furnace and firing them at a temperature between 1600°C and 2000°C to reduce the manganese oxide and obtain a manganese-containing gas. Alternatively, a reducing agent such as carbon is placed in a furnace containing the precursor and manganese oxide, and firing them at a temperature between 1600°C and 2000°C to reduce the manganese oxide and obtain a manganese-containing gas.

[0072] The amount of manganese compound added per 1g of precursor may be, for example, 0.15g to 3.0g, or 0.2g to 2.5g.

[0073] As described above, a phosphorescent ceramic with high thermal conductivity can be obtained using this example manufacturing method. The phosphorescent ceramic contains aluminum nitride and manganese.

[0074] The above describes a method for manufacturing phosphor ceramics. However, phosphor ceramics may also be obtained by the following process, for example. Explanations of points that overlap are omitted.

[0075] (Variation 1) In the process of obtaining phosphor ceramics, instead of arranging the manganese compound so that it does not directly contact the precursor, the manganese-containing compound may be brought into contact with the surface of the precursor and fired at a temperature in the range of 1600°C to 2000°C. This makes it possible to obtain phosphor ceramics with high thermal conductivity.

[0076] (Modification 2) In the process of obtaining phosphor ceramics, instead of arranging the manganese compound so that the manganese-containing gas does not come into direct contact with the precursor, the manganese-containing gas may be introduced into the atmosphere and the precursor may be fired in a range of 1600°C to 2000°C. This makes it possible to obtain phosphor ceramics with high thermal conductivity. For example, the manganese-containing gas may be obtained by firing a manganese-containing compound in a furnace different from the furnace containing the precursor in a range of 1600°C to 2000°C. The obtained gas may then be introduced into the furnace containing the precursor and the precursor may be fired in a range of 1600°C to 2000°C.

[0077] (Variation 3) In the process of obtaining phosphorescent ceramics, instead of obtaining a manganese-containing gas from a manganese-containing compound, a manganese-containing gas may be obtained using elemental manganese. The obtained gas may be brought into contact with a precursor, and the precursor may be fired at a temperature between 1600°C and 2000°C. This makes it possible to obtain phosphorescent ceramics with high thermal conductivity.

[0078] <Application Examples> (Light-emitting device) Figure 4 is a cross-sectional view showing an example of a light-emitting device including a phosphor ceramic. The light-emitting element 1 is placed on the bottom surface 2a of a recess in a ceramic substrate 2 which has a recess. The ceramic substrate 2 has a bottom surface 2a and a bottom surface 2b located on the opposite side of the bottom surface 2a. The light-emitting element 1 is electrically connected to wiring 4. The wiring 4 includes an anode and a cathode. The wiring 4 runs from the bottom surface 2a to the bottom surface 2b through a through hole that penetrates the ceramic substrate 2. In addition, a translucent member 3 is placed on the top surface 2c of the ceramic substrate 2 on the same side as the bottom surface 2a of the recess. The translucent member 3 is bonded to the ceramic substrate 2 by an adhesive 5 placed on the top surface 2c.

[0079] The light-emitting element 1 is a semiconductor light-emitting element having a peak wavelength in the range of 230 nm to 330 nm. The light-emitting element 1 is, for example, In X Al Y Ga 1-X-Y N may be (where 0 ≤ X, 0 ≤ Y, X + Y ≤ 1). The light-emitting element 1 may, for example, have a positive and negative pair of electrodes on the same side. The light-emitting element 1 may be flip-chip mounted on, for example, wiring 4. If the light-emitting element 1 is flip-chip mounted on wiring 4, the side opposite to the side where the pair of electrodes is formed becomes the light extraction surface. The number of light-emitting elements 1 arranged in one light-emitting device may be one or more.

[0080] The phosphor ceramics of this embodiment can also be used as the ceramic substrate 2. The ceramic substrate 2 containing the phosphor ceramics has high thermal conductivity and can efficiently dissipate heat generated by the light-emitting element and the light-transmitting member 3. In addition, the ceramic substrate 2 can emit light when it receives light from the light-emitting element. For example, this property can be used to function as a marker to inform the surroundings that ultraviolet light is being generated. Furthermore, a reflective film may be formed on the side surface within the recess of the ceramic substrate 2. This can reflect light emitted from the light-emitting element 1 and increase the brightness of the light-emitting device. The ceramic substrate 2 can be obtained, for example, by injection molding, which involves a second firing of a precursor including the recess.

[0081] As the translucent member 3, the phosphor ceramic of this embodiment can be used. The phosphor ceramic has aluminum nitride as its base material and contains manganese. The translucent member 3 can be excited by light emitted from the light-emitting element 1 and emit light. The translucent member 3 emits light having a peak in the wavelength range of 590 nm to 620 nm. Furthermore, by including the phosphor ceramic of this embodiment in the translucent member 3, the thermal conductivity can be improved and heat dissipation can be enhanced. The thickness of the translucent member 3 may be, for example, within the range of 50 μm to 1000 μm, 50 μm to 500 μm, 60 μm to 450 μm, or 70 μm to 400 μm. The translucent member 3 can be obtained, for example, by injection molding and a second firing of the precursor.

[0082] The phosphorescent ceramic may be contained in only one of the light-transmitting member 3 and the ceramic substrate 2, or in both. If the phosphorescent ceramic is contained in both the light-transmitting member 3 and the ceramic substrate 2, the heat generated in the light-transmitting member 3 can be efficiently dissipated through the ceramic substrate 2. [Examples]

[0083] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0084] <Example 1> (Preparation process for the precursor) A raw material mixture was obtained by dry mixing 95% by mass of AlN powder and 5% by mass of yttrium oxide powder. The central particle size Da of the AlN powder was 1.1 μm, and the central particle size De of the yttrium oxide powder was 0.7 μm. The ratio of De to Da, De / Da, was 0.64. 15 parts by mass of paraffin wax was added as a binder to 100 parts by mass of the raw material mixture, and the mixture was kneaded using a kneader to obtain a kneaded product. The kneaded product was fed into an injection molding machine and molded to a shape of 13 mm (length) x 13 mm (width) x 3 mm (thickness) to obtain a molded body. The molded body was degreased in a nitrogen atmosphere at 500°C and atmospheric pressure (101.32 kPa) for 3 hours to obtain a degreased product. The carbon content in the degreased product was 500 ppm or less. In Example 1, the obtained degreased product was used as a precursor.

[0085] (Process for obtaining phosphorescent ceramics) 1.6 g of the precursor was placed on a boron nitride setter inside a boron nitride crucible. 1.0 g of manganese dioxide powder was also placed inside the same crucible. The crucible was then introduced into a carbon furnace, and the precursor underwent a second firing. The second firing was carried out in a nitrogen atmosphere at a gauge pressure of 30 kPa for 1 hour. The second firing temperature was 1800°C. A phosphorescent ceramic was obtained through this second firing.

[0086] <Example 2> (Preparation process for the precursor) A degreased body obtained under the same conditions as in Example 1 was subjected to a first firing to obtain a sintered body. The first firing was carried out in a nitrogen atmosphere at 1950°C, a gauge pressure of 0.03 MPa, and for 35 hours. The oxygen content in the sintered body, measured by an oxygen / nitrogen analyzer (EMGA-820, manufactured by Horiba, Ltd.), was below the detection limit and was at least less than 0.1% by mass.

[0087] (Process for obtaining phosphorescent ceramics) The phosphorescent ceramics were obtained by following the same procedure as in Example 1, except that 0.25 g of manganese dioxide was used and the second firing was performed at 1700°C for 2 hours.

[0088] <Example 3> The phosphorescent ceramics were obtained under the same conditions as in Example 2, except that the second firing was performed at 1800°C.

[0089] <Example 4> The phosphorescent ceramics were obtained under the same conditions as in Example 2, except that the second firing was performed at 1900°C.

[0090] <Example 5> The phosphorescent ceramics were obtained under the same conditions as in Example 2, except that the second firing was performed at 2000°C.

[0091] <Example 6> A phosphorescent ceramic was obtained under the same conditions as in Example 2, except that 0.5 g of manganese dioxide was used and the second firing was performed at 1600°C.

[0092] <Example 7> The phosphorescent ceramics were obtained under the same conditions as in Example 6, except that the second firing was performed at 1700°C.

[0093] <Example 8> The phosphorescent ceramics were obtained under the same conditions as in Example 6, except that the second firing was performed at 1800°C.

[0094] <Example 9> The phosphorescent ceramics were obtained under the same conditions as in Example 6, except that the second firing was performed at 1900°C.

[0095] <Example 10> The phosphorescent ceramics were obtained under the same conditions as in Example 6, except that the second firing was performed at 2000°C.

[0096] <Example 11> A phosphorescent ceramic was obtained under the same conditions as in Example 2, except that 1.2 g of manganese dioxide was used and the second firing was performed at 1800°C.

[0097] <Example 12> The phosphorescent ceramics were obtained under the same conditions as in Example 11, except that the second firing was performed at 1900°C.

[0098] <Example 13> A phosphorescent ceramic was obtained under the same conditions as in Example 2, except that 2.4 g of manganese dioxide was used and the second firing was performed at 1900°C.

[0099] <Reference example 1> Except for using 0.15 g of manganese dioxide and performing the second firing at 1900°C, aluminum nitride ceramics according to Reference Example 1 were obtained under the same conditions as in Example 2.

[0100] <Comparative Example 1> A raw material mixture was obtained by dry mixing 95% by mass of AlN powder, 4% by mass of yttrium oxide powder, and 1% by mass of manganese dioxide powder. 15 parts by mass of paraffin wax was added to 100 parts by mass of the raw material mixture as a binder, and the mixture was kneaded using a kneader to obtain a compound. The compound was fed into an injection molding machine and molded to a shape with dimensions of 13 mm (length) x 13 mm (width) x 3 mm (thickness). The molded compound was degreased by heating it in a nitrogen fluid atmosphere (99% nitrogen gas) at 500°C and atmospheric pressure (101.32 kPa) for 3 hours to obtain a molded body. The resulting molded body was placed on a boron nitride setter inside a boron nitride crucible, and then placed in a carbon furnace using carbon as the internal furnace material for the heating element and insulation. The body was then fired in a nitrogen atmosphere (100% nitrogen gas) at 1900°C, gauge pressure (0.03 MPa), and for 1 hour to obtain phosphorescent ceramics.

[0101] <Rating> (XRD) X-ray diffraction (XRD) patterns were measured for the phosphor ceramics according to Example 11 using an X-ray diffractometer (SmartLab, manufactured by Rigaku Corporation). The X-ray source was CuKα1 line (λ=0.154059 nm), and the XRD patterns were measured under conditions of a tube voltage of 45 kV and a tube current of 200 mA. Figure 5 shows the XRD patterns indicating the diffraction intensity for the obtained diffraction angle (2θ). From top to bottom, Figure 5 shows the XRD patterns of the phosphor ceramics according to Example 11 and the X-ray diffraction patterns registered in the ICSD (Inorganic Crystal Structure Database) as references. From top to bottom, the reference XRD patterns are the X-ray diffraction patterns of AlN, MnO2, and Y2O3.

[0102] As shown in Figure 5, the phosphor ceramic according to Example 11 has a peak at approximately the same position as the diffraction angle 2θ of the XRD pattern of AlN, confirming that the phosphor ceramic according to Example 11 has almost the same structure as AlN.

[0103] (Excitation spectrum) The excitation spectrum of the phosphor ceramic according to Example 11 was measured using a spectrofluorometer (F-4500, manufactured by Hitachi High-Tech Science Corporation). Figure 6 shows the excitation spectrum with wavelength on the horizontal axis and intensity on the vertical axis. As shown in Figure 6, it was confirmed that the excitation spectrum of the phosphor ceramic according to Example 11 has a peak in the range of 230 nm to 250 nm. Furthermore, it was confirmed that the excitation spectrum of the phosphor ceramic according to Example 11 has a shoulder structure in the range of 260 nm to 300 nm. In addition, the obtained excitation spectrum has a shape and peak position similar to the excitation spectrum disclosed in Non-Patent Literature 1. Therefore, it can be inferred from the excitation spectrum that the phosphor ceramic is an aluminum nitride phosphor ceramic in which manganese is activated in aluminum nitride.

[0104] (Emission spectrum) For the phosphor ceramic according to Example 11, excitation light with an emission peak wavelength of 254 nm was irradiated as an excitation light source, and the emission spectrum was measured at room temperature (25°C ± 5°C). Figure 7 shows the emission spectrum with wavelength on the horizontal axis and intensity on the vertical axis. As shown in Figure 7, it was confirmed that the phosphor ceramic has an emission peak wavelength in the range of 590 nm to 620 nm. It was also confirmed that there is a peak at approximately 600 nm. Similarly, when the emission spectra were measured for the phosphor ceramics according to Example 1 and Example 8, the emission peak wavelength hardly changed in all cases. The obtained excitation spectra have a shape and peak position similar to the emission spectrum disclosed in Non-Patent Literature 1. Therefore, it can be inferred from the emission spectrum that the phosphor ceramic is an aluminum nitride phosphor ceramic in which manganese is activated in aluminum nitride.

[0105] Furthermore, 254nm light was irradiated onto the phosphorescent ceramics of Examples 1 to 13 and Comparative Example 1. In each case, the emission of light from the phosphorescent ceramics was visually confirmed. Additionally, after the irradiation of the 254nm light was stopped, an afterglow of approximately one minute was observed. Furthermore, when irradiated with 254nm light for 30 seconds, a phenomenon of increased emission compared to immediately after the start of irradiation was visually observed. Note that when Reference Example 1 was also irradiated with 254nm light, no emission was visually confirmed.

[0106] (Thermal conductivity) For the phosphor ceramics samples from Examples 1 to 13, the phosphor ceramics from Comparative Example 1, and the aluminum nitride ceramics from Reference Example 1, the thermal conductivity λ was determined based on the specific heat capacity Cp, the measured apparent density, and the thermal diffusivity α. The specific heat capacity Cp was determined using the specific heat capacity of aluminum nitride, which is 0.72 kJ / (kg·K). The results are shown in Tables 1 and 2.

[0107] (Elemental analysis) Elemental analysis was performed on each sample from Examples 1 to 13, Comparative Example 1, and Reference Example 1 to measure the content of aluminum, yttrium, oxygen, and manganese. Aluminum, yttrium, and manganese were determined by ICP emission spectroscopy. Oxygen was determined by oxygen-nitrogen analyzer. Trace analysis of manganese was also performed for Examples 13, Comparative Example 1, and Reference Example 1. The results for Examples 1 to 13 and Reference Example 1 are shown in Table 1. The results for Comparative Example 1 are shown in Table 2.

[0108] [Table 1]

[0109] [Table 2]

[0110] The results shown in Tables 1 and 2 confirm that the phosphor ceramics of Examples 1 to 13 have higher thermal conductivity than the phosphor ceramic of Comparative Example 1. The manganese content was less than 50 ppm in Example 1 and less than 10 ppm in Examples 2 to 13. It was also confirmed that the manganese content in the phosphor ceramic of Example 13 was 5 ppm. It was confirmed that the manganese content in the phosphor ceramic of Comparative Example 1 was 7 ppm. It was confirmed that the manganese content in the aluminum nitride ceramic of Reference Example 1 was at least less than 1 ppm. Furthermore, it was confirmed that the yttrium content and oxygen content in the phosphor ceramics of Examples 2 to 13 were less than 0.1% by mass.

[0111] (SEM) SEM observation was performed on the phosphor ceramics according to Example 1 and Example 11. For the SEM observation, a straight line was drawn across an arbitrary 127 μm × 88 μm region on a cross-sectional SEM image observed at 1000x magnification, and the length from grain boundary to grain boundary of AlN particles overlapping this line was measured, and the average value was calculated. Figures 8A and 8B are the cross-sectional SEM images used to calculate the average value, respectively. SEM observation confirmed that the average grain size of the crystalline phase in Example 1, shown in Figure 8A, was approximately 1.9 μm. SEM observation also confirmed that the average grain size of the crystalline phase in Example 11, shown in Figure 8B, was approximately 4.3 μm. Therefore, it was confirmed that the grain size of Example 11, which used a sintered body as a precursor, was larger.

[0112] The embodiments and examples of the phosphor ceramics of this disclosure have been described above, but this disclosure can also take the following configuration. (Section 1) The process involves preparing a precursor whose base material is aluminum nitride, The aforementioned precursor is brought into contact with a gas containing manganese to obtain phosphorescent ceramics. A method for producing phosphorescent ceramics containing phosphors. (Section 2) A method for producing phosphor ceramics according to item 1, comprising firing the precursor at a temperature in the range of 1600°C to 2000°C in the step of obtaining the phosphor ceramics. (Section 3) The method for producing phosphor ceramics according to item 1 or 2, wherein the manganese-containing gas is obtained by reducing manganese oxide. (Section 4) The method for producing phosphor ceramics according to item 3, wherein the amount of manganese oxide charged is 0.15 g or more and 3.0 g or less per 1 g of precursor. (Section 5) The method for producing phosphor ceramics according to any one of claims 1 to 4, wherein the precursor is a sintered body whose base material is aluminum nitride. (Section 6) The precursor contains oxygen, The method for producing phosphor ceramics according to item 5, wherein the oxygen content is 0.3% by mass or less. (Section 7) Prepare a phosphor ceramic manufactured by the manufacturing method described in any one of items 1 to 6, Prepare an excitation light source, A method for manufacturing a light-emitting device, comprising arranging the phosphor ceramic at a position where it is irradiated by light emitted from the excitation light source. (Section 8) A phosphorescent ceramic containing aluminum nitride, yttrium, and manganese, The phosphor ceramics wherein the oxygen content in the phosphor ceramics is less than 2.4% by mass. (Section 9) The phosphor ceramic according to item 8, wherein the oxygen content is 1% by mass or less. (Section 10) The phosphorescent ceramic according to item 8 or 9, wherein the manganese content is 50 ppm or less. (Section 11) The phosphor ceramic according to any one of claims 8 to 10, wherein the excitation spectrum of the phosphor ceramic has a peak in the wavelength range of 230 nm to 250 nm. (Section 12) The phosphor ceramic according to any one of claims 8 to 11, wherein the emission spectrum of the phosphor ceramic has a peak in the wavelength range of 590 nm to 620 nm. (Section 13) Excitation light source and A light-emitting device comprising a phosphor ceramic according to any one of claims 8 to 12, which is positioned at a location where light emitted by the excitation light source is irradiated. [Explanation of Symbols]

[0113] 1 Light-emitting element 2. Ceramic substrate 2a Bottom surface of recess 2b Bottom side 2c Top surface 3 Translucent material 4 Wiring 5. Adhesive 100 Light-emitting devices

Claims

1. The process involves preparing a precursor whose base material is aluminum nitride, The aforementioned precursor is brought into contact with a gas containing manganese to obtain phosphorescent ceramics. Includes, A method for producing phosphor ceramics, comprising firing the precursor at a temperature of 1600°C to 2000°C in the step of obtaining the phosphor ceramics.

2. The method for producing phosphor ceramics according to claim 1, wherein the manganese-containing gas is obtained by reducing manganese oxide.

3. The method for producing phosphor ceramics according to claim 2, wherein the amount of manganese oxide added is 0.15 g or more and 3.0 g or less per 1 g of precursor.

4. The method for producing phosphor ceramics according to claim 1 or 2, wherein the precursor is a sintered body whose base material is aluminum nitride.

5. The precursor contains oxygen, The method for producing phosphor ceramics according to claim 4, wherein the oxygen content is 0.3% by mass or less.

6. To prepare phosphor ceramics manufactured by the manufacturing method described in claim 1 or 2, Prepare an excitation light source, A method for manufacturing a light-emitting device, comprising arranging the phosphor ceramic at a position where it is irradiated by light emitted from the excitation light source.

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