Alpha-sialon phosphor, light emitting device, and method for manufacturing alpha-sialon phosphor

Abstract

An α-sialon phosphor containing Eu element, wherein the density of crystal defects is 1.0 x 10 15 spins / g or less as a value of the spin density of a signal near g = 2 detected by electron spin resonance measurement at 25°C. Also, an α-sialon phosphor containing Eu element, wherein the density of crystal defects is 1.0 x 10 15 spins / g or less as a value of the spin density of a signal near g = 2 detected by electron spin resonance measurement at 200°C.

Description

Technical Field

[0001] This invention relates to an α-type silon phosphor, a light-emitting device, and a method for manufacturing an α-type silon phosphor. Background Technology

[0002] Alpha-type silon phosphors, which are formed by activating rare earth elements such as Eu, are suitable for wavelength conversion components in white LEDs because they can efficiently convert blue light into long-wavelength light.

[0003] In α-type silicon phosphors, the Si-N bonds in typical α-type silicon nitride crystals are replaced by Al-N and Al-O bonds. To maintain electroneutrality, they possess a structure where specific elements (Ca, as well as Li, Mg, Y, or lanthanides other than La and Ce) are infiltrated and dissolved within the crystal lattice. By making a portion of the infiltrated element a rare-earth element that serves as the luminescence center, fluorescence properties are exhibited. Specifically, α-type silicon phosphors with Ca dissolved and partially replaced by Eu are relatively efficiently excited in a broad wavelength region from ultraviolet to blue, exhibiting yellow or orange luminescence.

[0004] Various attempts have been made to further improve the fluorescence properties of α-type silon phosphors (e.g., patent documents 1-3).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-96882

[0008] Patent Document 2: Japanese Patent No. 6667025

[0009] Patent Document 3: Japanese Patent No. 6785333 Summary of the Invention

[0010] White LEDs using α-type silron phosphors as wavelength conversion components could be considered for automotive applications.

[0011] In automotive applications, it is required that the various properties of white LEDs remain unchanged at high temperatures. However, preliminary research by the inventors has revealed that white LEDs using conventional α-type silron phosphors as wavelength conversion components exhibit significant changes in luminescence characteristics at high temperatures.

[0012] The present invention was made in view of this situation. One of the objects of the present invention is to provide an α-type silron phosphor whose luminescence characteristics do not easily change even under high temperature environments when used as a wavelength conversion component of a white LED.

[0013] The inventors have completed the invention described below, which solves the above-mentioned problems.

[0014] 1. An α-type silon phosphor containing Eu, wherein,

[0015] The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 25 °C, is 1.0 × 10⁻⁶. 15 spins / g or less.

[0016] 2. An α-type silon phosphor containing Eu, wherein,

[0017] The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 200℃, is 1.0 × 10⁻⁶. 15 spins / g or less.

[0018] 3. The α-type silon phosphor according to 2, wherein,

[0019] The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 25 °C, is 1.0 × 10⁻⁶. 15 spins / g or less.

[0020] 4. The α-type silon phosphor according to any one of 1 to 3, wherein,

[0021] The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 300℃, is 1.0 × 10⁻⁶. 15 spins / g or less.

[0022] 5. The α-type silon phosphor according to any one of 1 to 4, wherein,

[0023] The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 600 °C, is 9.5 × 10⁻⁶. 15 spins / g or less.

[0024] 6. The α-type silon phosphor according to any one of 1 to 5,

[0025] Its internal quantum efficiency at 200℃ is over 87%.

[0026] 7. The α-type silon phosphor according to any one of 1 to 6,

[0027] Its internal quantum efficiency at 300℃ is over 80%.

[0028] 8. The α-type silon phosphor according to any one of 1 to 7, wherein,

[0029] The internal quantum efficiency maintenance rate, expressed as {(internal quantum efficiency at 24℃) / (internal quantum efficiency at 300℃)}×100[%), is above 89%.

[0030] 9. The α-type silon phosphor according to any one of 1 to 8, wherein,

[0031] The external quantum efficiency maintenance rate, expressed as {(external quantum efficiency at 24℃) / (external quantum efficiency at 300℃)}×100[%), is above 88%.

[0032] 10. The α-type silon phosphor according to any one of 1 to 9, wherein,

[0033] Composed of the general formula: (M1) x M2 y Eu z (Si) 12-(m+n) Al m+n (O) n N 16-n )express,

[0034] In the general formula,

[0035] M1 is a monovalent Li element.

[0036] M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and the lanthanides excluding La and Ce.

[0037] 0≤x<2.0, 0≤y<2.0, 0<z≤0.5, 0<x+y, 0.3≤x+y+z≤2.0, 0<m≤4.0, 0<n≤3.0.

[0038] 11. A light-emitting device comprising:

[0039] Light-emitting elements; and

[0040] The wavelength conversion section includes any one of the α-type silon phosphors described in 1 to 10, and converts the light emitted from the light-emitting element to a longer wavelength.

[0041] 12. A method for manufacturing an α-type silon phosphor, comprising the following steps:

[0042] The firing process yields blocky α-type silon phosphors containing Eu.

[0043] The pulverization process involves pulverizing the blocky α-type silon phosphor to obtain powdered α-type silon phosphor.

[0044] The N2 annealing process involves annealing the powdered α-type silon phosphor in a nitrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours.

[0045] The H2 annealing process involves annealing the powdered α-type silane phosphor in a hydrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours.

[0046] In the acid treatment step, the powdered α-type silon phosphor after the H2 annealing step is subjected to acid treatment using an acidic aqueous solution.

[0047] The luminescent properties of white LEDs using the α-type silron phosphor of the present invention as wavelength conversion components do not easily change even at high temperatures. Attached Figure Description

[0048] Figure 1 This is a schematic cross-sectional view showing an example of the structure of a light-emitting device. Detailed Implementation

[0049] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0050] In the accompanying drawings, the same reference numerals are used to denote the same constituent elements, and descriptions are omitted where appropriate.

[0051] To avoid complications, when multiple identical constituent elements exist in the same figure, sometimes only one of them is labeled, instead of all of them.

[0052] The accompanying drawings are for illustrative purposes only. The shapes or dimensions of the parts in the drawings may not necessarily correspond to actual objects.

[0053] In this specification, the expressions "X~Y" in the description of numerical ranges, unless otherwise specified, mean above X and below Y. For example, "1~5% by mass" means "more than 1% by mass and less than 5% by mass".

[0054] In this specification, "α-type silon phosphor containing Eu" is sometimes abbreviated as "α-type silon phosphor".

[0055] In this specification, "signal near g=2" literally means a signal with a g value near 2 in electron spin resonance measurements. Specifically, near g=2 means g=2±0.02.

[0056] <α-type silon phosphor>

[0057] The α-type silon phosphor of this embodiment contains Eu. Alternatively, the α-type silon phosphor of this embodiment is an Eu-activated α-type silon phosphor.

[0058] The α-type silon phosphor of this embodiment satisfies one or both of the following (1) and (2).

[0059] (1) The density of crystal defects in the α-type silon phosphor of this embodiment, as the spin density of the signal near g=2 detected by electron spin resonance measurement at 25°C, can be 1.0 × 10⁻⁶. 15 sp ins / g or less. This value is preferably 1.0 × 10⁻⁶. 14 spins / g or higher and 8.0 × 10 14 Spins / g or less, more preferably 1.0 × 10⁻⁶ 13 spins / g or higher and 6.0 × 10 14 spins / g or less.

[0060] (2) The density of crystal defects in the α-type silon phosphor of this embodiment, as the spin density of the signal near g=2 detected by electron spin resonance measurement at 200°C, can be 1.0 × 10⁻⁶. 15 Spins / g or less. This value is preferably 1.0 × 10⁻⁶. 14 spins / g or higher and 8.0 × 10 14 Spins / g or less, more preferably 1.0 × 10⁻⁶ 13 spins / g or higher and 6.0 × 10 14 spins / g or less.

[0061] The inventors have investigated the reasons for the changes in luminescence properties under high-temperature environments from various perspectives. Through their research, the inventors believe that the density of crystal defects, obtained through electron spin resonance (ESR) measurements, may be related to the degree of change in luminescence properties. This is because the presence of crystal defects typically leads to a decrease in luminescence properties.

[0062] Based on the above considerations, the inventors remanufactured an α-type silon phosphor with a sufficiently low density of crystal defects, obtained by electron spin resonance (ESR) measurements at 25°C and / or 200°C. Then, by using this novel α-type silon phosphor as a wavelength conversion component in a white LED, it was possible to manufacture a white LED whose luminescence characteristics do not easily change even under high-temperature conditions.

[0063] The statement that the density of crystal defects is sufficiently small at 200℃ means that there are few crystal defects even at high temperatures. It is believed that if the density of crystal defects is small at high temperatures, various properties will not easily change at high temperatures during vehicle operation, and therefore the luminescence properties will not easily change either.

[0064] Furthermore, if the density of amorphous defects is sufficiently small even at 25℃ (not 200℃), it is believed that there is a corresponding tendency for crystal defects to decrease at high temperatures. That is, if the density of crystal defects is sufficiently small at 25℃, it is believed that the luminescent properties are not easily changed even at high temperatures.

[0065] The α-type cylon phosphor of this embodiment can be manufactured through appropriate manufacturing processes. Specifically, the α-type cylon phosphor of this embodiment can be manufactured by performing two annealing processes: an N2 annealing process in which the powdered α-type cylon phosphor is annealed under nitrogen atmosphere and an H2 annealing process in which the powdered α-type cylon phosphor is annealed under hydrogen atmosphere. If the manufacturing method is inappropriate, the α-type cylon phosphor of this embodiment may sometimes not be obtained.

[0066] The manufacturing method will be explained in detail later.

[0067] The α-type silon phosphor of this embodiment will continue to be described.

[0068] Composition of fluorescent cells

[0069] The composition of the α-type silon phosphor in this embodiment can be represented, for example, as follows:

[0070] General formula: (M1) x M2 y Eu z (Si) 12-(m+n) Al m+n (O) n N 16-n ).

[0071] In the above general formula,

[0072] M1 is a monovalent Li element.

[0073] M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and the lanthanides (excluding La and Ce).

[0074] 0≤x<2.0, 0≤y<2.0, 0<z≤0.5, 0<x+y, 0.3≤x+y+z≤2.0, 0<m≤4.0, 0<n≤3.0.

[0075] The solid solution composition of α-type silon phosphors is represented by x, y, z in the above general formula and m and n determined by the associated Si / Al ratio or O / N ratio. Especially when M2 contains Ca, α-type silon phosphors are stabilized over a wide range of compositions, and a portion of them is replaced by Eu, which serves as the luminescent center, thereby obtaining phosphors that emit visible light in the range of yellow to orange when excited by light in the ultraviolet to blue wavelength region.

[0076] Typically, α-type silron phosphors are either a second crystalline phase different from α-type silron phosphors or an unavoidable amorphous phase, making it impossible to strictly define their solid solution composition through compositional analysis. The preferred crystalline phase for α-type silron phosphors is a single α-type silron phase, but it may also include aluminum nitride or its polymorphs as other crystalline phases.

[0077] Properties of fluorescent particles

[0078] Alpha-type silon phosphors are usually processed in the form of aggregates of alpha-type silon phosphor particles, i.e., alpha-type silon phosphor powder.

[0079] Alpha-type silon phosphor particles typically contain multiple primary particles that form secondary particles in a bulk.

[0080] Median particle size (D) of α-type silon phosphor powder 50 The lower limit of the median particle size of the α-type silon phosphor powder is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. Furthermore, the upper limit of the median particle size of the α-type silon phosphor powder is preferably 30 μm or less, more preferably 20 μm or less. The median particle size of the α-type silon phosphor powder is the size of the secondary particles mentioned above. That is, D 50 Preferably, the particle size is 1 μm or more and 30 μm or less, more preferably 5 μm or more and 30 μm or less, and even more preferably 10 μm or more to 20 μm or less. By setting the median particle size of the α-type silon phosphor powder to 5 μm or more, the transparency of the wavelength conversion component can be further improved. On the other hand, by setting the median particle size of the α-type silon phosphor powder to 30 μm or less, the generation of debris can be suppressed when the wavelength conversion component is cut using a cutting machine or the like.

[0081] Here, the median particle size (D) of the α-type silon phosphor powder is... 50 The median particle size refers to the cumulative fraction based on the volume datum of laser diffraction scattering according to JIS R1629:1997. Incidentally, in the case of α-type silon phosphor powder containing secondary particles, the median particle size obtained by laser diffraction scattering reflects the size of the secondary particles.

[0082] There are no particular limitations on the shape of alpha-type silon phosphor particles. Shapes can include spheres, cubes, cylinders, irregular shapes, etc.

[0083] Various properties at various temperatures

[0084] In addition to the density (spin density) of crystal defects at 25°C and 200°C mentioned above, the performance of α-type silon phosphors at high temperatures can sometimes be further improved by designing one or more of the characteristics described below.

[0085] In this embodiment, the density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance measurement at 300°C, is preferably 1.0 × 10⁻⁶. 15 Spins / g or less, more preferably 1.0 × 10⁻⁶ 14 spins / g or more and 1.0 × 10 15 Spins / g or less, more preferably 4.0 × 10⁻⁶. 14 spins / g or higher and 9.0 × 10 14 spins / g or less.

[0086] In this embodiment, the density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance measurement at 600°C, is preferably 9.5 × 10⁻⁶. 15 Spins / g or less, more preferably 5.0 × 10⁻⁶. 15 spins / g or higher and 9.5 × 10 15 Spins / g or less, more preferably 7.5 × 10⁻⁶. 15 spins / g or higher and 9.5 × 10 15 spins / g or less.

[0087] The α-type silon phosphor of this embodiment preferably has an internal quantum efficiency of 87% or higher at 200°C, more preferably 88% or higher. The closer this value is to 100%, the better, but in practice it is 95% or lower or 93% or lower. That is, the internal quantum efficiency at 200°C is preferably 87% or higher and 95% or lower, more preferably 88% or higher and 93% or lower.

[0088] The α-type silon phosphor of this embodiment preferably has an external quantum efficiency of 80% or more at 300°C, more preferably 82% or more. The closer this value is to 100%, the better, but in practice it is 90% or less or 88% or less. That is, the external quantum efficiency at 200°C is preferably 80% or more and 90% or less, more preferably 82% or more and 88% or less.

[0089] In the α-type silon phosphor of this embodiment, the internal quantum efficiency retention rate, expressed as {(internal quantum efficiency at 24°C) / (internal quantum efficiency at 300°C)}×100[%), is preferably 89% or more, more preferably 89% or more and 99% or less, and even more preferably 90% or more and 99% or less.

[0090] In the α-type silon phosphor of this embodiment, the external quantum efficiency retention rate, expressed as {(external quantum efficiency at 24°C) / (external quantum efficiency at 300°C)}×100[%), is preferably 88% or more, more preferably 88% or more and 99% or less, and even more preferably 89% or more and 97% or less.

[0091] <Light-emitting device>

[0092] Figure 1 This is a schematic cross-sectional view illustrating the structure of a light-emitting device.

[0093] like Figure 1 As shown, the light-emitting device 100 includes a light-emitting element 120, a heat sink 130, a housing 140, a first lead frame 150, a second lead frame 160, a bonding wire 170, a bonding wire 172, and a composite 40.

[0094] The light-emitting element 120 is mounted on a designated area on the upper surface of the heat sink 130. By mounting the light-emitting element 120 on the heat sink 130, the heat dissipation of the light-emitting element 120 can be improved. Alternatively, a packaging substrate can be used instead of the heat sink 130.

[0095] The light-emitting element 120 is a semiconductor element that emits excitation light. For example, an LED chip that generates light with a wavelength of 300 nm or more and 500 nm or less, corresponding to near-ultraviolet to blue light, can be used as the light-emitting element 120. An 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. Furthermore, another 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.

[0096] A roughly funnel-shaped recess with an aperture that gradually widens from the bottom surface upwards is formed in the housing 140. A light-emitting element 120 is disposed on the bottom surface of the recess. The wall of the recess surrounding the light-emitting element 120 functions as a reflector.

[0097] The composite 40 fills the aforementioned recess in which the housing 140 forms a wall. The composite 40 is a wavelength conversion component that lengthens the wavelength of the excitation light emitted from the light-emitting element 120. As the composite 40, the phosphor 1 of this embodiment is dispersed in the sealing material 30 such as resin. The light-emitting device 100 emits a mixed color of light from the light-emitting element 120 and light generated from the phosphor particles 1 that absorb and excite the light from the light-emitting element 120. Preferably, the light-emitting device 100 emits white light through the mixing of the light from the light-emitting element 120 and the light generated from the phosphor 1.

[0098] Incidentally, examples of resins that can be used as sealing materials 30 in composite 40 include transparent resins such as silicone resin, epoxy resin, and polyurethane resin. Composite 40 can be manufactured, for example, by adding the α-type silron phosphor of this embodiment to a liquid resin or powdered glass or ceramic and mixing it uniformly, and then curing or sintering it by heat treatment.

[0099] In the light-emitting device 100 of this embodiment, by using the aforementioned α-type silron phosphor as phosphor 1, changes in light-emitting characteristics at high temperatures are suppressed. Therefore, the light-emitting device 100 is preferably used for automotive applications. However, it should be noted firstly that the application of the light-emitting device 100 is not limited to automotive applications. The light-emitting device 100 can also be applied to non-automotive lighting applications or display device applications, etc.

[0100] Incidentally, in Figure 1 The example shown is a surface-mount type light-emitting device, but the light-emitting device is not limited to surface-mount type, and can also be bullet type, COB (chip-on-board) type, CSP (chip-scale package) type.

[0101] <Preparation method of α-type silon phosphor>

[0102] The method for manufacturing an α-type silon phosphor according to this embodiment includes the following steps:

[0103] The firing process yields blocky α-type silon phosphors containing Eu.

[0104] The above-mentioned blocky α-type silon phosphor is pulverized to obtain powdered α-type silon phosphor.

[0105] The N2 annealing process involves annealing the above-mentioned powdered α-type silon phosphor in a nitrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours.

[0106] The H2 annealing process involves annealing the aforementioned powdered α-type silane phosphor in a hydrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours; and

[0107] In the acid treatment step, the powdered α-type silon phosphor after the H2 annealing step is subjected to acid treatment using an acidic aqueous solution.

[0108] In the method for manufacturing α-type silon phosphors in this embodiment, it is preferable that the H2 annealing process is performed after the N2 annealing process.

[0109] Furthermore, it is preferable to perform a panning process to classify the powdered α-type silon phosphor after the above-mentioned acid treatment process.

[0110] The manufacturing method described above enables the production of α-type silron phosphors with particularly few crystal defects. While the details are not yet clear, it is speculated that the combination of N2 annealing and H2 annealing processes is effective in reducing crystal defects.

[0111] The following is a supplementary explanation of each process.

[0112] · Firing process

[0113] The firing process can be carried out with reference to the conventional manufacturing method of α-type cyron phosphors. To give a simple example, a bulk α-type cyron phosphor containing Eu can be obtained by the following steps: (i) First, raw materials (nitrides or oxides of each element, etc.) containing the elements constituting an Eu-containing α-type cyron phosphor are mixed to obtain a mixture; (ii) The mixture is filled into a boron nitride container and fired in a nitrogen atmosphere at a temperature above 1650°C and below 1950°C.

[0114] Regarding the firing process, reference can be made to the description and embodiments in paragraphs 0036 to 0044 of International Publication No. 2020 / 203483. Furthermore, reference can also be made to other publicly known documents.

[0115] • Grinding process

[0116] During the calcination process, ingot-shaped α-type cyron phosphors are typically produced. By pulverizing these ingot-shaped α-type cyron phosphors using crushers, mortars, ball mills, vibratory mills, jet mills, or similar pulverizers, powdered α-type cyron phosphors can be obtained.

[0117] By adjusting the degree of grinding, the particle size distribution, such as the median particle size, of α-type silon phosphors can be adjusted.

[0118] In addition to the crushing process, a sieving and grading process can also be performed. By performing the sieving and grading process, the particle size distribution, such as the median particle size, can be adjusted more precisely.

[0119] Furthermore, the following steps can be performed: dispersing the pulverized powdered α-type silon phosphor in an aqueous solution and allowing it to stand for a certain period of time to remove small particles that are not easily precipitated. This allows for more precise adjustment of particle size distribution, such as the median particle size.

[0120] ·N2 annealing process

[0121] The temperature for the N2 annealing process only needs to be above 1200℃ and below 1700℃, but it is preferred to be above 1300℃ and below 1600℃.

[0122] The N2 annealing process can be completed in a time of 5 hours or more but less than 30 hours, preferably 8 hours or more but less than 25 hours.

[0123] The pressure in the N2 annealing process is not particularly limited, for example, it is 0.02 MPa·G or more and 0.9 MPa·G or less, preferably 0.02 MPa·G or more and 0.2 MPa·G or less.

[0124] The N2 annealing process can be carried out in a mixed gas environment of N2 and other inert gases (noble gases, etc.), but it is preferable to carry it out in a gas environment consisting essentially of N2. Furthermore, even in a mixed gas environment, the proportion of N2 in the mixed gas is preferably greater than 50% by volume, more preferably greater than 75% by volume. It is believed that in this way, crystal defects in the α-type silon phosphor will be further reduced.

[0125] H2 annealing process

[0126] The temperature of the H2 annealing process only needs to be above 1200℃ and below 1700℃, preferably above 1300℃ and below 1600℃.

[0127] The H2 annealing process can be carried out for more than 5 hours but less than 30 hours, but preferably more than 8 hours but less than 25 hours.

[0128] The pressure in the H2 annealing process is not particularly limited, for example, it is 0.02 MPa or more and 0.9 MPa or less, preferably 0.02 MPa or more and 0.1 MPa or less.

[0129] The H2 annealing process can be carried out in a mixed gas environment of H2 and other inert gases (noble gases, etc.), but it is preferable to carry it out in a gas environment consisting essentially of H2. Furthermore, even when carried out in a mixed gas environment, the proportion of H2 in the mixed gas is preferably greater than 50% by volume, more preferably greater than 75% by volume. It is believed that in this way, crystal defects in α-type silon phosphors will be further reduced.

[0130] Acid treatment process

[0131] In the acid treatment process, for example, powdered α-type silon phosphor is placed in an acidic aqueous solution and stirred using a stirrer.

[0132] Examples of acidic aqueous solutions include an acidic aqueous solution containing one acid selected from hydrofluoric acid, nitric acid, hydrochloric acid, etc., or a mixed acid aqueous solution obtained by mixing two or more of the aforementioned acids. More preferably, this includes an aqueous solution of hydrofluoric acid containing only hydrofluoric acid and a mixed acid aqueous solution obtained by mixing hydrofluoric acid and nitric acid. The concentration of the original acidic aqueous solution can be appropriately set according to the strength of the acid used, preferably 0.7% or more and 100% or less, more preferably 0.7% or more and 40% or less. Furthermore, the temperature during acid treatment is preferably 60°C or more and 90°C or less, and the reaction time (immersion time) is preferably 15 minutes or more and 80 minutes or less.

[0133] High-speed stirring facilitates thorough acid treatment of the particle surface. "High-speed" here depends on the stirring apparatus used, but when using a laboratory-grade magnetic stirrer, the stirring speed is, for example, above 400 rpm, practically between 400 rpm and 500 rpm. For the general purpose of stirring to continuously supply fresh acid to the particle surface, a stirring speed of around 200 rpm is sufficient. However, by performing high-speed stirring above 400 rpm, thorough particle surface treatment is easily achieved through both chemical and physical processes.

[0134] By selecting appropriate stirring conditions, foreign matter or heterogeneous phases on the phosphor surface (which may lead to a decrease in luminescence properties) are thoroughly removed. As a result, it is believed that the crystal defects of the α-type silron phosphor as a whole are further reduced. Consequently, it is believed that changes in luminescence properties under high-temperature environments can be further reduced.

[0135] Grading process

[0136] To adjust the particle size distribution of α-type silon phosphors, a certain classification process can be performed. Classification can be carried out under dry or wet conditions. Various industrial devices can be used for classification, such as sedimentation tanks, hydrocyclones, centrifuges, cyclone separators, and air separators. Among these, sedimentation tank-based elution classification is preferred, although the specific classification method is not limited to sedimentation tank-based elution classification.

[0137] The embodiments of the present invention have been described above, but these are merely examples, and various other structures can also be employed. Furthermore, the present invention is not limited to the above embodiments, and modifications and alterations within the scope of achieving the objectives of the present invention are included in the present invention.

[0138] Example

[0139] The embodiments of the present invention will be described in detail based on examples and comparative examples. It should be noted, however, that the present invention is not limited to these examples.

[0140] <Preparation of α-type silon phosphors>

[0141] (Examples 1, 2 and Comparative Example 1)

[0142] The α-type silon phosphor was manufactured using the following steps.

[0143] (1) Firing process

[0144] Inside the glove box, as the composition of the raw material powders, 62.4 parts by weight of silicon nitride powder (manufactured by Ube Industries, Ltd., E10 grade), 22.5 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, E grade), 2.2 parts by weight of europium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd., RU grade), and 12.9 parts by weight of calcium nitride powder (manufactured by Koju ndo Chemical Lab. Co., Ltd.) were dry-mixed and then passed through a nylon sieve with a mesh size of 250 μm to obtain a raw material mixed powder. 120g of the raw material powder was filled into a covered cylindrical boron nitride container (manufactured by DENKA COMPANY LIMITED, N-1 grade) with an internal volume of 0.4 liters.

[0145] The raw material powder mixture, along with its container, was heated (fired) at 1800°C for 16 hours in an electric furnace with a carbon heater under atmospheric nitrogen pressure. Since the calcium nitride contained in the raw material powder mixture is easily hydrolyzed in air, the boron nitride container filled with the raw material powder mixture was quickly placed into the electric furnace after being removed from the glove box, and immediately subjected to vacuum degassing to prevent the calcium nitride from reacting.

[0146] (2) Crushing process

[0147] The calcined material obtained in (1) above was appropriately pulverized or crushed using a mortar and pestle, so that it all passed through a sieve with a mesh size of 150 μm, to obtain phosphor powder. The crystal phase of the phosphor powder was investigated by powder X-ray diffraction using CuKα rays, and the existing crystal phase was α-type silon.

[0148] (3) N2 annealing process

[0149] The powdered α-type silon phosphor obtained in the pulverization process described in (2) above was placed in a boron nitride container and covered. The container was then placed in a heating furnace and heated under nitrogen atmosphere according to the conditions described in the "N2 Annealing" column of Table 1 below. After natural cooling, all the orange powder recovered from the container was passed through a sieve with a mesh size of 75 μm. Thus, N2 annealed phosphor powder was obtained.

[0150] (4) H2 annealing process

[0151] The phosphor powder annealed with N2 as described in (3) was placed in a boron nitride container and the container was covered. The container was placed in a heating furnace and heated in a hydrogen atmosphere. The heating conditions were set as described in the "H2 Annealing" column of Table 1 below. After natural cooling, all the orange powder recovered from the container was passed through a sieve with a mesh size of 75 μm. Thus, the phosphor powder annealed with H2 was obtained.

[0152] (5) Acid treatment process

[0153] First, 50 mL of 50% hydrofluoric acid and 50 mL of 70% nitric acid were mixed to prepare a stock solution. Then, 300 mL of distilled water was added to this stock solution to dilute its concentration to 25%, thus preparing 400 mL of a mixed acid aqueous solution.

[0154] 30g of phosphor powder recovered after the H2 annealing process in (4) above was added to the mixed acid aqueous solution. The temperature of the mixed acid aqueous solution was kept at 80°C and stirred for 60 minutes at 450 rpm using a magnetic stirrer.

[0155] After stirring, the acid adhering to the phosphor was thoroughly washed with distilled water. The washed phosphor powder was then recovered by filtration and dried.

[0156] The particle size distribution of the dried phosphor powder was determined using a Microtrac MT3300EXII (MicrotracBEL Corp.) by laser diffraction scattering in accordance with JIS R1629:1997.

[0157] Specifically, firstly, 0.5 g of powdered α-type silane phosphor was added to 100 cc of deionized water and dispersed for 3 minutes using an Ultrasonic Homogenizer US-150E (NIHONSEIKIKAISHALTD., chip size φ20 mm, amplitude 100%, oscillation frequency 19.5 kHz, amplitude approximately 31 μm) to obtain a dispersion. The dispersion was then placed in an MT3300EXII reactor, and the particle size distribution was measured.

[0158] The median particle size D was determined based on the obtained particle size distribution. 50 .

[0159] The conditions for N2 annealing and H2 annealing processes, and D 50 As shown in Table 1.

[0160] [Table 1]

[0161] Table 1

[0162]

[0163] <Electron Spin Resonance Measurement>

[0164] Regarding the α-type silon phosphors of Examples 1, 2, and Comparative Example 1, electron spin resonance measurements were performed as follows. Then, the density of crystal defects in the α-type silon phosphors at 25°C, 200°C, 300°C, and 600°C was used as the spin density value of the signal near g=2 to determine the values.

[0165] (Measurement Procedure)

[0166] The sample powder (approximately 60 mg) was placed in an ESR sample tube and placed in the apparatus, allowing simulated air (flow rate: 20 mL min⁻¹) to circulate within the sample tube. ESR measurements were performed at room temperature (25 °C) near g = 2.

[0167] Then, the temperature was increased to 200°C at a rate of 30°C / min and held for 30 minutes before ESR measurements were performed near g=2.

[0168] Subsequently, the temperature was increased to 300°C at a rate of 30°C / min and held for 30 minutes before ESR measurements were performed near g=2.

[0169] Subsequently, the temperature was increased to 600°C at a rate of 30°C / min and held for 30 minutes before ESR measurements were performed near g=2.

[0170] (Measuring apparatus and measuring conditions)

[0171] The BRUKER ESR apparatus "EMXplus" and the BRUKER high-temperature chamber "ER4114HT" were used. The measurement conditions are as follows.

[0172] Magnetic field scanning range: around 3350~3550G

[0173] Modulation: 100kHz, 5G

[0174] Microwave: 9.67 GHz, 1 mW

[0175] Scanning time: 80s x 4 times

[0176] Time constant: 327.68ms

[0177] Data points: 1000

[0178] (Analysis of measurement data)

[0179] ESR spectroscopy is typically observed as a first-order differential curve to precisely observe the fluctuations in the absorption spectrum of electromagnetic waves. Since the absorption intensity is proportional to the spin number, the ESR spectrum is integrated twice, and the differential curve is converted into an integral curve. The spin number of the sample is then quantified based on the peak area ratio compared to the standard sample.

[0180] Regarding the integration range, in the first-order differential curve, after subtracting from the lines passing through g = 2.0171 and g = 1.9838 as baselines, the range of g = 2.0171 to 1.9838 was integrated. From this, the peak area originating from the sample near g = 2 was determined.

[0181] The analysis used the ESR software "WinEPR" manufactured by BRUKER.

[0182] (Calculation of spin number and spin density)

[0183] Regarding the spin number of the sample at 25°C, an ESR determination was performed on a secondary standard sample (an ion-implanted polyethylene film) with a known spin number, and the spin number was determined based on the ratio of its peak area to the standard standard sample. Furthermore, the spin number per unit mass of the sample at 25°C (spin density [spins / g]) was obtained by dividing the spin number of the sample by the mass of the sample to be measured [g].

[0184] Incidentally, the spin number of the secondary standard sample (an ion-implanted polyethylene film) was determined by separately measuring the ESR of the primary standard sample (copper sulfate pentahydrate) with a known spin number at 25°C, and based on the ratio of its peak area to the primary standard sample.

[0185] The spin number of the sample at 200°C was determined using the same method as at 25°C, by calculating the peak area ratio with that of the secondary standard sample (an ion-implanted polyethylene film). This ratio was then multiplied by the measurement temperature ((273+200)[K]) ÷ room temperature ((273+25)[K]) (Curie's law), thus correcting for the influence of the measurement temperature on the signal intensity. Furthermore, the spin number per unit mass of the sample at 200°C (spin density [spins / g]) was obtained by dividing the spin number of the sample by the mass of the sample being measured (g).

[0186] Similarly, the spin density [spins / g] of the sample at 300 °C was determined. Incidentally, when performing temperature correction based on Curie's law, the value was multiplied by the measurement temperature ((273+300)[K]) ÷ room temperature ((273+25)[K]).

[0187] Similarly, the spin density [spins / g] of the sample at 600 °C was determined. Incidentally, when performing temperature correction based on Curie's law, the result was multiplied by the measurement temperature ((273+600)[K]) ÷ room temperature ((273+25)[K]).

[0188] (Replenish)

[0189] The absorption intensity in the ESR spectrum varies depending on the measurement conditions. Therefore, the Q value of the resonator, receiver gain, number of accumulations, modulation (G), switching time (ms), microwave power (mW), sample tube inner diameter (mm), resonator center position (mm), length of the inserted sample (mm), and the influence of spin quantum number were appropriately corrected during the analysis.

[0190] The results are shown in Table 2 below. The units of the values ​​are spins / g.

[0191] [Table 2]

[0192] Table 2

[0193]

[0194] <Evaluation: Temperature-based changes in luminescence properties>

[0195] Regarding the α-type silon phosphors of each embodiment and comparative example, the absorbance, internal quantum efficiency, and external quantum efficiency, as well as their temperature dependence, were corrected by re-excitation method by subtracting the re-excitation fluorescence from the overall fluorescence using a spectrophotometer (QE-2100 manufactured by Otsuka Electronics Co., Ltd.), and the absorbance, internal quantum efficiency, and external quantum efficiency were determined.

[0196] The absorbance, internal quantum efficiency, and external quantum efficiency were determined by changing the sample temperature from room temperature to 300°C, and the temperature changes of the internal and external quantum efficiencies were evaluated.

[0197] As a quantitative indicator of temperature change, the internal quantum efficiency at each temperature, “internal quantum efficiency maintenance rate”, relative to the value of internal quantum efficiency at room temperature, and the external quantum efficiency at each temperature, “external quantum efficiency maintenance rate”, relative to the value of external quantum efficiency at room temperature, were calculated.

[0198] The evaluation results are summarized in Tables 3, 4 and 5.

[0199] [Table 3]

[0200]

[0201] [Table 4]

[0202]

[0203] [Table 5]

[0204]

[0205] As understood from the table above, the density of crystal defects at 25℃ or 200℃ is greater than 1.0 × 10⁻⁶. 15 In Comparative Example 1, where spin s / g is significantly lower, the decrease in both internal and external quantum efficiency is particularly pronounced at a high temperature of 300°C.

[0206] On the other hand, the density of crystal defects at 25℃ or 200℃ is 1.0 × 10⁻⁶. 15 In Examples 1 and 2 with spins / g or less, the decrease in internal and external quantum efficiencies is suppressed even at high temperatures. That is, the change in luminescence properties is small even at high temperatures. It can be said that the phosphors of Examples 1 and 2 are preferably suitable for automotive applications.

[0207] This application claims priority based on Japanese Patent Application No. 2023-058890, filed on March 31, 2023, the disclosure of which is incorporated herein in its entirety.

[0208] Symbol Explanation

[0209] 1 fluorescent

[0210] 30 sealing material

[0211] 40 complex

[0212] 100 light-emitting devices

[0213] 120 light-emitting element

[0214] 130 heatsink

[0215] 140 housing

[0216] 150 First lead frame

[0217] 160 second lead frame

[0218] 170 joint line

[0219] 172 joint line

Claims

1. An α-type silon phosphor containing Eu, wherein, The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 25 °C, is 1.0 × 10⁻⁶. 15 spins / g or less; The composition of the α-type cyron phosphor is given by the general formula: (M1) x M2 y Eu z (Si) 12-（m+n） Al m+n (O) n N 16-n )express, In the general formula, M1 is a monovalent Li element. M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and the lanthanides excluding La and Ce, and must contain at least Ca. 0≤x<2.0, 0≤y<2.0, 0<z≤0.5, 0<x+y, 0.3≤x+y+z≤2.0, 0<m≤4.0, 0<n≤3.

0.

2. An α-type silon phosphor containing Eu, wherein, The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 200 °C, is 1.0 × 10⁻⁶. 15 spins / g or less; The composition of the α-type cyron phosphor is given by the general formula: (M1) x M2 y Eu z (Si) 12-（m+n） Al m+n (O) n N 16-n )express, In the general formula, M1 is a monovalent Li element. M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and the lanthanides excluding La and Ce, and must contain at least Ca. 0≤x<2.0, 0≤y<2.0, 0<z≤0.5, 0<x+y, 0.3≤x+y+z≤2.0, 0<m≤4.0, 0<n≤3.

0.

3. The α-type silon phosphor according to claim 2, wherein, The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 25 °C, is 1.0 × 10⁻⁶. 15 spins / g or less.

4. The α-type silon phosphor according to any one of claims 1 to 3, wherein, The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 300 °C, is 1.0 × 10⁻⁶. 15 spins / g or less.

5. The α-type silon phosphor according to any one of claims 1 to 3, wherein, The density of crystal defects in the α-type silon phosphor, as the spin density of the signal near g=2 detected by electron spin resonance at 600 °C, is 9.5 × 10⁻⁶. 15 spins / g or less.

6. The α-type silon phosphor according to any one of claims 1 to 3, Its internal quantum efficiency at 200℃ is over 87%.

7. The α-type silon phosphor according to any one of claims 1 to 3, Its internal quantum efficiency at 300℃ is over 80%.

8. The α-type silon phosphor according to any one of claims 1 to 3, wherein, The internal quantum efficiency maintenance rate, expressed as {(internal quantum efficiency at 24℃) / (internal quantum efficiency at 300℃)} × 100 [%], is above 89%.

9. The α-type silon phosphor according to any one of claims 1 to 3, wherein, The external quantum efficiency maintenance rate, expressed as {(external quantum efficiency at 24℃) / (external quantum efficiency at 300℃)} × 100 [%], is over 88%.

10. The α-type silon phosphor according to any one of claims 1 to 3, wherein, M2 is Ca.

11. A light-emitting device comprising: Light-emitting elements; and The wavelength conversion section includes an α-type silon phosphor as described in any one of claims 1 to 3, and converts the light emitted from the light-emitting element to a longer wavelength.

12. A method for manufacturing an α-type silon phosphor, comprising the following steps: The firing process yields blocky α-type silon phosphors containing Eu. The pulverization process involves pulverizing the blocky α-type silon phosphor to obtain powdered α-type silon phosphor. The N2 annealing process involves annealing the powdered α-type silon phosphor in a nitrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours. The H2 annealing process involves annealing the powdered α-type silane phosphor in a hydrogen atmosphere at a temperature range of 1200°C to 1700°C and for a time range of 5 to 30 hours. The acid treatment process involves applying an acidic aqueous solution to the powdered α-type silon phosphor after the H2 annealing process. The composition of the α-type cyron phosphor is given by the general formula: (M1) x M2 y Eu z (Si) 12-（m+n） Al m+n (O) n N 16-n )express, In the general formula, M1 is a monovalent Li element. M2 is one or more divalent elements selected from the group consisting of Mg, Ca, and the lanthanides excluding La and Ce, and must contain at least Ca. 0≤x<2.0, 0≤y<2.0, 0<z≤0.5, 0<x+y, 0.3≤x+y+z≤2.0, 0<m≤4.0, 0<n≤3.0.

Images