Phosphor powder, composite, light-emitting device, and method for manufacturing phosphor powder

Abstract

This phosphor powder comprises a red phosphor represented by general formula (Srx,Ca1-x-y,Euy)AlSi(N,O)3, and has an identical crystal phase to that of CASN. In the general formula: x < 1, and 1-x-y > 0. In addition, when this phosphor powder is irradiated by a blue excitation light at a wavelength of 455 nm, the fluorescence spectrum peak wavelength is between 600 nm and 610 nm inclusive, and the fluorescence spectrum half-width is 73 nm or narrower.

Description

[Technical Field]

[0001] The present invention relates to a phosphor powder, a composite, a light-emitting device, and a method for producing the phosphor powder. [Background technology]

[0002] To manufacture white LEDs, research is being conducted into red phosphors that convert blue light from blue LED chips into red light. Known red phosphors include CASN and SCASN. As a specific example, Patent Document 1 discloses a compound represented by the general formula M a Sr b Ca c Al d Si e N f It contains a crystalline phase expressed by 4000mW / mm 2 The phosphor is characterized by a quantum efficiency maintenance rate of 85% or more when excited by light. In this general formula, M represents an activator element; <a<0.05、0.95≦b≦1、0≦c<0.1、a+b+c=1、0.7≦d≦1.3、0.7≦e≦1.3、2.5≦f≦3.5である。 [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-077800 A Summary of the Invention [Problem to be solved by the invention]

[0004] Various improvements have been made to the red phosphor that converts blue light from a blue LED chip into red light, but there is still room for improvement in terms of brightness when used in white LEDs.

[0005] The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to improve the brightness of white LEDs by improving the red phosphor. [Means for solving the problem]

[0006] The present inventors have completed the invention provided below and solved the above problems.

[0007] According to the present invention, CASN has the same crystalline phase as the general formula (Sr x ,Ca 1-x-y ,EU y )AlSi(N,O)3, x<1, 1-xy>0, The peak wavelength of the fluorescence spectrum when irradiated with blue excitation light having a wavelength of 455 nm is 600 nm or more and 610 nm or less, The phosphor powder has a fluorescence spectrum with a half-width of 73 nm or less. is provided.

[0008] Further, according to the present invention, A composite comprising the above phosphor powder and a sealing material that seals the phosphor powder. is provided.

[0009] Further, according to the present invention, A light-emitting device comprising a light-emitting element that emits excitation light and the composite that converts the wavelength of the excitation light. is provided.

[0010] Further, according to the present invention, The method for producing the phosphor powder described above comprises: a mixing step of mixing the starting materials to form a raw material mixed powder; a firing step of firing the raw material mixed powder to obtain a fired product; Including, The method for producing a phosphor powder, wherein the starting material contains SCASN phosphor core particles having an average particle size of 5 μm or more and 30 μm or less. is provided. [Effects of the Invention]

[0011] By using the red phosphor of the present invention, the brightness of a white LED can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the structure of a light-emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, similar components are denoted by similar reference numerals and descriptions thereof will be omitted where appropriate. To avoid complexity, when there are multiple identical components in the same drawing, only one of them may be labeled with a symbol, and not all of them. The drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0014] In this specification, unless otherwise specified, the term "approximately" means that a range is included taking into consideration manufacturing tolerances, assembly variations, and the like.

[0015] Strictly speaking, "brightness" is a physical quantity (unit: cd / m) defined using the luminous intensity of a light source and the angle at which the light source is viewed. 2 ) However, the term "luminance" in this specification is used in a broader sense. The term "luminance" in this specification includes the meanings of "the degree of brightness of light perceived by humans" and "the sensory intensity of light taking into account the visibility of the human eye."

[0016] <Phosphor powder> The phosphor powder of this embodiment has the same crystalline phase as CASN and is represented by the general formula (Sr x ,Ca 1-x-y ,EU y The red phosphor is represented by the general formula: )AlSi(N,O)3, where x<1 and 1-xy>0. When the phosphor powder of this embodiment is irradiated with blue excitation light having a wavelength of 455 nm, the peak wavelength of the fluorescence spectrum is 600 nm to 610 nm, preferably 602 nm to 609 nm, and the half width of this fluorescence spectrum is 73 nm or less, preferably 70 nm to 73 nm, more preferably 71 nm to 73 nm.

[0017] In order to improve the brightness of white LEDs by improving the red phosphor, it is possible to simply increase the peak intensity of the emission spectrum of the red phosphor itself. On the other hand, in the case of red light, the luminance can be improved by shortening the peak "wavelength" of the emission (fluorescence) spectrum, due to the relationship with luminosity. In other words, in the wavelength region of red light, humans tend to perceive light with a short wavelength as being "brighter" than light with a long wavelength. Based on this, in this embodiment, a compound having the general formula (Sr x ,Ca 1-x-y ,EU y The red phosphor represented by )AlSi(N,O)3 was designed so that the peak wavelength of the fluorescence spectrum when irradiated with blue excitation light of 455 nm is between 600 nm and 610 nm. This "shortening of the peak wavelength" can improve the brightness of white LEDs.

[0018] Incidentally, according to the knowledge of the present inventors, in the past, when the peak wavelength of a red phosphor was designed to be shorter, the peak intensity could be reduced. However, in this embodiment, the red phosphor is designed so that the half-width of the fluorescence spectrum is 73 nm or less, thereby increasing the peak intensity of the fluorescence spectrum (preventing the peak top from becoming lower). The phosphor particles of this embodiment, which have a fluorescence spectrum with a short peak wavelength and a narrow half-width, are preferably used to improve the brightness of white LEDs.

[0019] The phosphor powder of this embodiment can be obtained by appropriately selecting the raw materials, the ratio of each raw material used, the manufacturing procedure, and the manufacturing conditions. Regarding the selection of raw materials and the ratio of raw materials, it is preferable to use a larger amount of Sr-containing raw material and a smaller amount of Eu-containing raw material, and to add a "core" (described later). Regarding the manufacturing procedure and conditions, it is preferable to perform firing using a container made of a high-melting point metal, such as a container made of tungsten, molybdenum, or tantalum. Details of these will be described later.

[0020] The phosphor powder of this embodiment will be described further.

[0021] (crystal structure, elemental composition, etc.) The phosphor particles of this embodiment are made of a compound of the general formula (Sr x ,Ca 1-x-y ,EU y The red phosphor is represented by the general formula: )AlSi(N,O)3. In this general formula, x<1, 1-xy>0. Here, (N,O) indicates that some of the N atoms are inevitably replaced with O atoms.

[0022] The crystalline phase can be confirmed by powder X-ray diffraction. A single crystalline phase is preferable, but other phases may be present as long as they do not significantly affect the phosphor properties. The presence or absence of other phases can be determined by, for example, the presence or absence of peaks other than those due to the target crystalline phase by powder X-ray diffraction. The framework of CASN is composed of (Si,Al)-N4 tetrahedrons, with Ca atoms located in the gaps between the framework. 2+ A part of Eu acts as a luminescence center 2+ By substituting with, a red phosphor is obtained.

[0023] Regarding x, preferably 0.9 < x < 1, more preferably 0.92 < x < 1, and even more preferably 0.95 < x < 1. According to the findings of the inventors, the larger the amount of Sr in the phosphor particles of this embodiment, the more likely the peak wavelength and full width at half maximum of the fluorescence spectrum will fall within the aforementioned numerical ranges. As another index from the perspective of "a large amount of Sr", the molar ratio of Sr / (Sr + Ca) is preferably 0.96 or more and 0.999 or less, more preferably 0.97 or more and 0.999 or less.

[0024] Regarding y, preferably y < 0.01, more preferably 0.0005 < y < 0.005, and even more preferably 0.001 < y < 0.005. Usually, from the perspective of peak intensity, it is preferable for the phosphor particles to contain a certain amount of Eu, but from the perspective of short wavelength conversion, in this embodiment, it is preferable that the amount of Eu is relatively small.

[0025] (Median diameter) The median diameter of the phosphor particles of this embodiment is preferably 1 μm or more and 40 μm or less, more preferably 10 μm or more and 30 μm or less. In applications where blue light from a blue LED is converted into red light, a median diameter of this level is preferable in terms of the balance of various performances such as luminance and conversion efficiency. The median diameter can be measured as a volume-based value by the laser diffraction scattering method. Adjustment of the median diameter can be achieved by appropriately applying known means such as grinding and sieving. Details will be described later.

[0026] <Manufacturing method of phosphor powder> The phosphor powder of this embodiment can be obtained by appropriately selecting the selection of raw materials, the usage ratio of each raw material, manufacturing procedures, manufacturing conditions, etc. Specifically, the phosphor powder of this embodiment is preferably · A mixing step of mixing starting materials to form a raw material mixed powder, and · A firing step of firing the raw material mixed powder to obtain a fired product. [[ID=]] It can be manufactured by going through these steps. Also, when manufacturing the phosphor powder, there may be additional steps other than these.

[0027] The following describes the mixing process, the firing process, and additional processes other than these processes.

[0028] (Mixing process) In the mixing process, starting materials are mixed to obtain a raw material mixed powder. Examples of the starting materials include europium compounds, strontium compounds such as strontium nitride, calcium compounds such as calcium nitride, silicon nitride, aluminum nitride, and the like. The form of each starting material is preferably powdery.

[0029] Examples of the europium compound include oxides containing europium, hydroxides containing europium, nitrides containing europium, oxynitrides containing europium, halides containing europium, and the like. These can be used alone or in combination of two or more. Among these, it is preferable to use europium oxide, europium nitride, and europium fluoride alone, and it is more preferable to use europium oxide alone.

[0030] In the firing process, europium is divided into those that dissolve, those that volatilize, and those that remain as heterogeneous components. The heterogeneous components containing europium can be removed by acid treatment or the like. However, when too much is generated, components insoluble in acid treatment are generated, and the luminance decreases. Also, if it is a heterogeneous phase that does not absorb excess light, it may remain as it is, and this heterogeneous phase may contain europium.

[0031] The amount of the europium compound used is not limited, but when assuming that the charging ratio is directly reflected in the final composition ratio, y in the above general formula is preferably used in an amount such that y < 0.01, more preferably 0.0005 < y < 0.005, and even more preferably 0.001 < y < 0.005. Incidentally, when using the core particles described later, the amount of europium in the core particles is not included in y in the above inequality. In terms of shortening the wavelength, it is preferable that the amount of europium in this embodiment is relatively small.

[0032] On the other hand, assuming that the charge ratio is directly reflected in the final composition ratio, the amount of strontium compound used is preferably such that x in the above general formula satisfies 0.9≦x<1, more preferably 0.92≦x<1, and even more preferably 0.95≦x<1. Incidentally, when core particles described below are used, x in the above inequality does not include the amount of strontium in the core particles. In terms of shortening the wavelength, it is preferable that the amount of strontium is relatively large in this embodiment.

[0033] In this embodiment, the starting material (raw material mixed powder) preferably contains SCASN phosphor core particles having a median diameter of 5 μm or more and 30 μm or less. In other words, a portion of the starting material is preferably SCASN phosphor core particles having an average particle diameter of 5 μm or more and 30 μm or less. The average particle diameter is more preferably 10 μm or more and 20 μm or less. In this specification, the SCASN phosphor core particles are also referred to simply as "core particles" or "cores."

[0034] Although the details are unclear, it is thought that by using core particles, crystallization will proceed from the core particles as a starting point during the subsequent firing process. This is thought to result in a different way of crystal growth compared to firing without core particles (for example, by using cores, it is thought that the composition of each particle will be more uniform than when cores are not used). As a result, it is thought that it will be easier to obtain phosphor powder with a fluorescence spectrum whose peak wavelength is between 600 nm and 610 nm and whose half-width is 73 nm or less when irradiated with blue excitation light at a wavelength of 455 nm.

[0035] The core particle may be a red phosphor represented by the same general formula as the red phosphor of the present embodiment. In other words, the core particle has a composition identical to or similar to that of the red phosphor of the present embodiment, although the peak wavelength of the fluorescence spectrum when irradiated with blue excitation light having a wavelength of 455 nm is not necessarily 600 nm or more and 610 nm or less, and / or the half-width of the fluorescence spectrum is not 73 nm or less.

[0036] When core particles are used, the amount thereof is, for example, 1% by mass or more and 20% by mass or less, and preferably 2% by mass or more and 15% by mass or less, of the total amount of the raw material mixed powder.

[0037] The core particles can be obtained, for example, through substantially the same process as that for the phosphor powder of this embodiment. That is, in the manufacturing process of the phosphor powder of this embodiment, the core particles can be obtained in substantially the same manner except that the core particles are not added in the mixing step. The composition (general formula) of the core particles is also preferably the same as that of the phosphor powder of this embodiment.

[0038] In the mixing step, the raw material mixed powder can be obtained, for example, by dry mixing the starting materials or by wet mixing the starting materials in an inert solvent that does not substantially react with the starting materials and then removing the solvent. Examples of mixing devices that can be used include a small mill mixer, a V-type mixer, a rocking mixer, a ball mill, and a vibration mill. After mixing using the device, aggregates can be removed using a sieve, if necessary, to obtain the raw material mixed powder. In order to prevent deterioration of the starting materials and unintended incorporation of oxygen, the mixing step is preferably carried out in a nitrogen atmosphere or in an environment with as little moisture (humidity) as possible.

[0039] (Firing process) In the firing step, the raw material mixed powder obtained in the mixing step is fired to obtain a fired product. The firing temperature in the firing step is preferably 1800°C or higher and 2100°C or lower, and more preferably 1900°C or higher and 2000°C or lower. When the firing temperature is equal to or higher than the lower limit, grain growth of the phosphor particles proceeds more effectively. As a result, the light absorptance, internal quantum efficiency, and external quantum efficiency can be further improved. When the firing temperature is equal to or lower than the upper limit, decomposition of the phosphor particles can be further suppressed. As a result, the light absorptance, internal quantum efficiency, and external quantum efficiency can be further improved. Other conditions in the firing step, such as the temperature rise time, temperature rise rate, heating retention time, and pressure, are not particularly limited and may be adjusted appropriately depending on the raw materials used. Typically, the heating retention time is preferably 3 hours or more and 30 hours or less, and the pressure is preferably 0.6 MPa or more and 10 MPa or less (gauge pressure). From the perspective of controlling the oxygen concentration, the firing step is preferably carried out in a nitrogen gas atmosphere. In other words, the firing step is preferably carried out in a nitrogen gas atmosphere with a pressure of 0.6 MPa or more and 10 MPa or less (gauge pressure).

[0040] During firing, it is preferable to heat the mixture by filling it into a container that is unlikely to react with the mixture during firing, such as a high-melting-point metal container, specifically a container with an inner wall made of tungsten, molybdenum, or tantalum, which can prevent the generation of heterogeneous phases.

[0041] (Powderization process) A powdering step may be carried out as an additional step. The fired product obtained through the firing step is usually a granular or lumpy sintered body. If the fired product is lumpy and difficult to handle, the fired product can be first powdered by crushing, grinding, classification, or other treatments, either alone or in combination, to obtain a sintered powder. Specific examples of the treatment method include pulverizing the sintered body to a predetermined particle size using a general pulverizer such as a ball mill, a vibration mill, a jet mill, etc. However, care should be taken because excessive pulverization may produce fine particles that easily scatter light or may cause crystal defects on the particle surfaces, resulting in a decrease in luminous efficiency.

[0042] (Annealing process) An annealing step may be performed as an additional step. Specifically, after the firing step, an annealing step may be performed in which the fired powder is annealed at a temperature lower than the firing temperature in the firing step to obtain an annealed powder. The annealing step is preferably carried out in a non-oxidizing atmosphere other than pure nitrogen, such as an inert gas such as a rare gas or nitrogen gas, a reducing gas such as hydrogen gas, carbon monoxide gas, hydrocarbon gas or ammonia gas, or a mixture of these, or in a vacuum, etc. It is particularly preferably carried out in a hydrogen gas atmosphere or an argon atmosphere. The annealing step may be performed under atmospheric pressure, under pressure, or under reduced pressure. The heat treatment temperature in the annealing step is preferably 1300° C. to 1400° C. The duration of the annealing step is not particularly limited, but is preferably 3 hours to 12 hours, more preferably 5 hours to 10 hours. The annealing step can significantly improve the luminous efficiency of the phosphor particles, and also improve transparency by removing distortions and defects due to the rearrangement of elements. The annealing step may result in the generation of heterogeneous phases, but these can be sufficiently removed by the steps described below.

[0043] (Acid treatment process) An acid treatment step may be performed as an additional step. In the acid treatment step, the annealed powder obtained in the annealing step is usually treated with acid. This can remove at least a portion of the impurities that do not contribute to light emission. Incidentally, it is presumed that the impurities that do not contribute to light emission are generated during the firing step and the annealing step.

[0044] The acid may be an aqueous solution containing one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid. Particularly preferred are hydrofluoric acid, nitric acid, and a mixed acid of hydrofluoric acid and nitric acid. The acid treatment can be carried out by dispersing the annealed powder in an aqueous solution containing the acid. The stirring time is, for example, from 10 minutes to 6 hours, preferably from 30 minutes to 3 hours. The stirring temperature can be, for example, from 40°C to 90°C, preferably from 50°C to 70°C. After the acid treatment step, the liquid in which the annealed powder is dispersed may be subjected to a boiling treatment. After the acid treatment step, substances other than the phosphor powder are separated by filtration, and if necessary, substances adhering to the phosphor particles may be washed with water. After washing with water, the phosphor powder is usually dried by natural drying or drying in a dryer. The dried phosphor powder may be placed in a crucible and heated to modify the surface.

[0045] Through the series of steps described above, the phosphor powder of this embodiment can be obtained.

[0046] (complex) The composite includes, for example, the above-described phosphor powder and a sealant that seals the phosphor powder in. In the composite, the above-described phosphor powder is dispersed in the sealant. The sealing material may be a known material such as resin, glass, ceramics, etc. Examples of the resin used for the sealing material include transparent resins such as silicone resin, epoxy resin, and urethane resin.

[0047] The composite may be produced by adding the phosphor powder according to the embodiment to a liquid resin, glass, ceramics, or the like, mixing the mixture uniformly, and then curing or sintering the mixture by heat treatment.

[0048] (Light-emitting device) 1 is a schematic cross-sectional view showing an example of the structure of a light emitting device. As shown in Fig. 1, the light emitting device 100 includes a light emitting element 120, a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, bonding wires 170 and 172, and a composite 40.

[0049] The light emitting element 120 is mounted in a predetermined region on the upper surface of the heat sink 130. Mounting the light emitting element 120 on the heat sink 130 can improve the heat dissipation properties of the light emitting element 120. Note that a packaging substrate may be used instead of the heat sink 130.

[0050] The light emitting element 120 is a semiconductor element that emits excitation light. For example, an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used as the light emitting element 120. One electrode (not shown) disposed on the upper surface of the light emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. The other electrode (not shown) formed on the upper surface of the light emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.

[0051] A generally funnel-shaped recess whose diameter gradually increases from the bottom toward the top is formed in case 140. Light emitting element 120 is provided on the bottom of the recess. The wall of the recess surrounding light emitting element 120 serves as a reflector.

[0052] The composite 40 is filled in the recess whose wall is formed by the case 140. The composite 40 is a wavelength conversion member that converts excitation light emitted from the light emitting element 120 into light with a longer wavelength. The composite of this embodiment is used as the composite 40, and the above-mentioned phosphor powder 1 is dispersed in an encapsulant 30 such as a resin. The light emitting device 100 emits a mixed color of light from the light emitting element 120 and light emitted from the phosphor powder 1 that is excited by absorbing the light from the light emitting element 120. Note that, in order to obtain a white mixed color (to make the light emitting device 100 a white LED), it is preferable that the composite 40 contains, for example, LuAG phosphor powder in addition to the phosphor powder 1 (it is preferable that LuAG phosphor powder is dispersed in the encapsulant 30 in addition to the phosphor powder 1). In this embodiment, the peak wavelength and half width of the fluorescence spectrum of the phosphor powder 1 are within certain numerical ranges, so that good white light can be easily obtained.

[0053] 1 shows a surface-mounted light-emitting device as an example, the light-emitting device is not limited to the surface-mounted type. The light-emitting device may be a bullet type, a COB (chip-on-board) type, a CSP (chip-scale package) type, or the like.

[0054] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0055] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, it should be noted that the present invention is not limited to the Examples.

[0056] <Example of core particle production> First, 61.38 g of α-type silicon nitride (Si3N4, manufactured by Ube Industries, Ltd., SN-E10 grade), 53.80 g of aluminum nitride (AlN, manufactured by Tokuyama Corporation, E grade), and 0.92 g of europium oxide (Eu2O3, manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a container and premixed. Next, in a glove box maintained in a nitrogen atmosphere with a moisture content of 1 mass ppm or less and an oxygen concentration of 50 ppm or less, 2.98 g of calcium nitride (Ca3N2, manufactured by Materion) and 120.92 g of strontium nitride (Sr3N2, purity 2N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) were further placed in the container and dry mixed. As a result, a raw material powder (mixed powder) was obtained.

[0057] In a glove box, 240 g of the raw material powder was placed in a tungsten container with a lid. After closing the lid, the container was removed from the glove box and placed in an electric furnace equipped with a carbon heater. The electric furnace was then evacuated to a vacuum until the pressure inside was 0.1 PaG or less. While continuing to evacuate, the temperature inside the electric furnace was raised to 600°C. After reaching 600°C, nitrogen gas was introduced into the electric furnace and the pressure inside the electric furnace was adjusted to 0.9 MPaG. Then, in a nitrogen gas atmosphere, the temperature inside the electric furnace was raised to 1950°C, and after reaching 1950°C, heat treatment was carried out for 8 hours. Then, heating was stopped and the mixture was cooled to room temperature. After cooling to room temperature, red lumps were recovered from the container. The recovered lumps were crushed in a mortar and sieved to adjust the particle size. By changing the method for adjusting the particle size, core particles with an average particle size of 11 μm and core particles with an average particle size of 18 μm were produced.

[0058] <Production of phosphor powder> Example 1 A container was charged with 54.96 g of α-type silicon nitride (Si3N4, manufactured by Ube Industries, Ltd., SN-E10 grade), 48.18 g of aluminum nitride (AlN, manufactured by Tokuyama Corporation, E grade), 0.41 g of europium oxide (Eu2O3, manufactured by Shin-Etsu Chemical Co., Ltd.), and 24.00 g of the above-prepared cores with an average particle size of 18 μm, and these were premixed. Next, in a glove box maintained in a nitrogen atmosphere with a moisture content of 1 mass ppm or less and an oxygen concentration of 50 ppm or less, 1.34 g of calcium nitride (Ca3N2, manufactured by Materion) and 111.11 g of strontium nitride (Sr3N2, purity 2N, manufactured by Kojundo Chemical Laboratory Co., Ltd.) were further weighed and dry-mixed into the container, thereby obtaining a raw material powder (mixed powder).

[0059] In a glove box, 240 g of the raw material powder was placed in a tungsten container with a lid. After closing the lid, the container was removed from the glove box and placed in an electric furnace equipped with a carbon heater. The electric furnace was then evacuated to a vacuum until the pressure inside was 0.1 PaG or less. While continuing to evacuate, the temperature inside the electric furnace was raised to 600°C. After reaching 600°C, nitrogen gas was introduced into the electric furnace and the pressure inside the electric furnace was adjusted to 0.9 MPaG. The temperature inside the electric furnace was then raised to 1950°C in a nitrogen gas atmosphere, and after reaching 1950°C, heat treatment was carried out for 8 hours. Heating was then terminated and the material was allowed to cool to room temperature. After cooling to room temperature, red lumps were recovered from the container. The recovered lumps were crushed, sieved, and the particle size was adjusted to obtain a red phosphor (fired powder).

[0060] The resulting fired powder was loaded into a tungsten container and quickly transferred to an electric furnace equipped with a carbon heater. The furnace was thoroughly evacuated until the pressure inside the furnace reached 0.1 PaG or less. Heating began while continuing the evacuation. When the temperature reached 600°C, argon gas was introduced into the furnace and the pressure inside the furnace was adjusted to atmospheric pressure. After the introduction of argon gas began, the temperature continued to rise to 1350°C. After the temperature reached 1350°C, the heat treatment took 8 hours. Then, heating was stopped and the material was cooled to room temperature. After cooling to room temperature, the annealed powder was recovered from the container. The recovered powder was passed through a sieve to adjust the particle size. This yielded a red phosphor (annealed powder).

[0061] The annealed powder was immersed in 2.0 M hydrochloric acid at room temperature for 1 hour so that the slurry concentration was 25% by mass. This resulted in an acid treatment. After the acid treatment, the hydrochloric acid slurry was boiled for 1 hour while being stirred. The boiled slurry was cooled to room temperature and filtered to separate the acid treatment solution from the synthesized powder. The synthesized powder after separation of the acid treatment solution was placed in a dryer set at a temperature between 100°C and 120°C for 12 hours. The dried powder after the acid treatment step was placed in an alumina crucible, and the temperature was increased at a rate of 10° C. / min in the atmosphere, followed by heat treatment at 400° C. for 3 hours. After the heat treatment, the powder was left to cool to room temperature. In this way, the phosphor powder of Example 1 was obtained.

[0062] The obtained phosphor sample was subjected to powder X-ray diffraction using CuKα radiation using an X-ray diffractometer (Ultima IV manufactured by Rigaku Corporation). The obtained X-ray diffraction pattern was identical to that of CaAlSiN3 crystals, confirming that the main crystalline phase had the same crystal structure as CaAlSiN3 crystals.

[0063] Example 2 The phosphor powder of Example 2 was obtained in the same manner as Example 1, except that the raw materials used were Si3N4 = 54.68 g, AlN = 47.93 g, Eu2O3 = 0.41 g, Ca3N2 = 0.17 g, Sr3N2 = 112.81 g, and nuclei (average particle size 18 μm) = 24.00 g.

[0064] Example 3 The phosphor powder of Example 3 was obtained in the same manner as Example 1, except that the raw materials used were Si3N4 = 54.94 g, AlN = 48.18 g, Eu2O3 = 0.41 g, Ca3N2 = 1.34 g, Sr3N2 = 111.13 g, and nuclei (average particle size 11 μm) = 24.00 g.

[0065] (Comparative Example 1) The phosphor powder of Comparative Example 1 was obtained in the same manner as in Example 1, except that the raw materials used were Si3N4 = 61.47 g, AlN = 53.88 g, Eu2O3 = 0.46 g, Ca3N2 = 3.12 g, and Sr3N2 = 121.07 g, and no nuclei were used.

[0066] (Comparative Example 2) The phosphor powder of Comparative Example 2 was obtained in the same manner as in Example 1, except that the raw materials used were Si3N4 = 61.38 g, AlN = 53.80 g, Eu2O3 = 0.92 g, Ca3N2 = 2.98 g, and Sr3N2 = 120.92 g, and no nuclei were used.

[0067] (Comparative Example 3) The phosphor powder of Comparative Example 3 was obtained in the same manner as in Example 1, except that the raw materials used were Si3N4 = 60.98 g, AlN = 53.46 g, Eu2O3 = 0.92 g, Ca3N2 = 1.35 g, and Sr3N2 = 123.29 g, and no nuclei were used.

[0068] Comparative Example 4 The phosphor powder of Comparative Example 4 was obtained in the same manner as in Example 1, except that the raw materials used were Si3N4 = 60.91 g, AlN = 53.39 g, Eu2O3 = 0.92 g, Ca3N2 = 1.03 g, and Sr3N2 = 123.75 g, and no nuclei were used.

[0069] <Median diameter measurement> Measurements were performed using a Microtrac MT3300EX II (Microtrac Bell Corporation) using the laser diffraction scattering method in accordance with JIS R1629:1997. 0.5 g of phosphor powder was added to 100 cc of ion-exchanged water and dispersed for 3 minutes using an Ultrasonic Homogenizer US-150E (Nippon Seiki Seisakusho Co., Ltd., tip size φ20 mm, amplitude 100%, oscillation frequency 19.5 kHz, amplitude approximately 31 μm). Particle size was then measured using the MT3300EX II. The median diameter was determined from the resulting particle size distribution.

[0070] <Fluorescence spectrum measurement> Fluorescence measurements were performed using a spectrofluorometer (Hitachi High-Technologies Corporation, F-7000) calibrated with rhodamine B and a secondary standard light source. A solid sample holder attached to the spectrophotometer was used to obtain a fluorescence spectrum at an excitation wavelength of 455 nm. From the obtained fluorescence spectrum, the peak wavelength and half-width of the fluorescence spectrum were calculated. Peak intensity (relative emission peak intensity) was also calculated.

[0071] A supplementary note on peak intensity (relative emission peak intensity) is provided below. The relative emission peak intensity is expressed as the peak height (%) of the emission spectrum obtained by irradiating 455 nm monochromatic light onto YAG:Ce (P46Y3 manufactured by Kasei Optonix Co., Ltd.), with the peak height obtained from the phosphor particles being measured being taken as 100%. In other words, the peak intensities in the examples and comparative examples are relative values ​​to the standard sample.

[0072] <Brightness evaluation> The luminance was evaluated by calculating the value I obtained by integrating the product of the fluorescence spectral intensity and luminosity at each wavelength in the wavelength range from 500 nm to 780 nm, with wavelength as the integral variable. The luminosity value was based on the standard relative luminosity for photopic vision, which is defined as 1 for light with a wavelength of 555 nm. It can be said that SCASN phosphor powders with a large I value can be preferably used for manufacturing high-brightness white LEDs.

[0073]

number

[0074] The raw material ratios and various measurement / evaluation results are shown in Table 1. In Table 1, "large amount of Sr added" means that Sr3N2 was used in an amount such that x in the general formula above satisfies 0.95≦x<1, at least in terms of the ratio of raw materials charged. In Table 1, the values ​​in the columns Si (molar ratio), Al (molar ratio), Eu (molar ratio), Ca (molar ratio), Sr (molar ratio), Eu + Sr + Ca, and Sr / (Sr + Ca) do not include elements in the core particles. In Table 1, the values ​​in the column Sr / (Sr+Ca) correspond to the value of x / (1-y) in the general formula described above.

[0075] [Table 1]

[0076] <Considerations of Examples and Comparative Examples> Although the peak wavelengths of the phosphor powders of Examples 1 to 3 were relatively short (600 nm or more and 610 nm or less), the peak intensities of these phosphor powders were as large as those of Comparative Examples 2 to 4 (peak wavelengths exceeding 610 nm). This is presumably because the phosphor powders of Examples 1 to 3 were designed so that the half-width was 73 nm or less. Furthermore, when Examples 1 to 3 and Comparative Example 1 are compared, which have similar peak wavelengths, Comparative Example 1 had a smaller peak intensity, probably because the half-width was more than 73 nm. Furthermore, the luminance I of the phosphor powders of Examples 1 to 3, which have "large peak intensities despite relatively short peak wavelengths," was 170 or more, which was clearly larger than that of Comparative Examples 1 to 4. This demonstrates that the phosphor powders of Examples 1 to 3 can be suitably used in the manufacture of high-luminance white LEDs.

[0077] This application claims priority based on Japanese Patent Application No. 2020-061212, filed on March 30, 2020, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0078] 1. Phosphor powder 30 Encapsulating material 40 Complex 100 Light-emitting device 120 Light-emitting element 130 Heatsink 140 cases 150 First lead frame 160 Second lead frame 170 Bonding Wire 172 Bonding Wire

Claims

1. CASN, which has the same crystalline phase as ｘ , Ca １－ｘ－ｙ , Eu ｙ )AlSi(N,O) ３ A phosphor powder made of a red phosphor represented by 0.9<x<1, 1-x-y>0, 0.0005<y; The peak wavelength of the fluorescence spectrum when irradiated with blue excitation light having a wavelength of 455 nm is 600 nm or more and 610 nm or less, the half-width of the fluorescence spectrum is 73 nm or less; A phosphor powder having a median diameter of 1 μm or more and 40 μm or less.

2. The phosphor powder according to claim 1, A phosphor powder in which y<0.

01.

3. 3. The phosphor powder according to claim 1, The phosphor powder has a molar ratio of Sr / (Sr+Ca) of 0.96 or more and 0.999 or less.

4. The phosphor powder according to any one of claims 1 to 3, The phosphor powder has a fluorescence spectrum having a half-width of 70 nm or more and 73 nm or less.

5. A phosphor powder according to any one of claims 1 to 4, and a sealing material that seals the phosphor powder; A complex comprising:

6. a light emitting element that emits excitation light; The composite according to claim 5, which converts the wavelength of the excitation light; A light emitting device comprising:

7. A method for producing a phosphor powder according to any one of claims 1 to 4, comprising: a mixing step of mixing the starting materials to form a raw material mixed powder; a firing step of firing the raw material mixed powder to obtain a fired product; Including, The method for producing a phosphor powder, wherein the starting material contains SCASN phosphor core particles having an average particle size of 5 μm or more and 30 μm or less.

8. 8. A method for producing a phosphor powder according to claim 7, The method for producing phosphor powder further comprises, after the firing step, an annealing step of annealing the fired powder at a temperature lower than the firing temperature in the firing step to obtain annealed powder.

9. 9. The method for producing a phosphor powder according to claim 8, The method for producing a phosphor powder further comprises an acid treatment step of acid-treating the annealed powder obtained in the annealing step.

Images