PHOSPHOR PARTICLE CONTAINING γ-AlON, PHOSPHOR POWDER CONTAINING SAME, LIGHTING FIXTURE, AND IMAGE DISPLAY DEVICE

Abstract

A phosphor particle which contains Mn and Eu as constituent elements, and contains γ-AlON, said phosphor particle comprising: a core part; and a coating part which coats at least part of the surface of the core part and exhibits a greater Eu content than does the core part.

Description

Phosphor particles containing γ-AlON, phosphor powder containing the same, lighting equipment, and image display device

[0001] The present disclosure relates to phosphor particles containing γ-AlON, phosphor powder containing the same, lighting equipment, and image display devices.

[0002] γ-AlON is a crystal having a cubic spinel type crystal structure, and a phosphor in which a specific metal element is dissolved in γ-AlON has been reported (Patent Document 1). ２＋ and Eu ２＋ In γ-AlON co-doped with Eu ２＋ From Mn ２＋ It is described that energy transfer occurs to the fluorine atom, and green light emission is observed with a relatively high external quantum efficiency.

[0003] International Publication No. 2007 / 099862

[0004] Inorganic Chemistry, 2015, Vol. 54, Issue 11, p. 5556-5565

[0005] The present inventors have discovered that phosphor powder containing phosphor particles that include Mn and Eu and contain γ-AlON, and that have a specific structure, has excellent internal quantum efficiency. The present disclosure is based on this new finding, and aims to provide a γ-AlON-containing phosphor powder that has excellent internal quantum efficiency. Another aim of the present disclosure is to provide a lighting device and an image display device that use the phosphor particles or phosphor powder.

[0006] The present disclosure provides the following items [1] to [9]. [1] A phosphor particle containing γ-AlON and containing Mn and Eu as constituent elements, the phosphor particle comprising a core portion and a coating portion covering at least a portion of the surface of the core portion and having a higher Eu content than the core portion. [2] The phosphor particle according to [1], wherein the Eu content in the coating portion is 1.0 to 6.0 mol % based on the total amount of elements contained in the coating portion. [3] The phosphor particle according to [1] or [2], wherein the Mn content in the coating portion is 0.3 to 2.0 mol % based on the total amount of elements contained in the coating portion. [4] The phosphor particle according to any one of [1] to [3], further containing Mg as a constituent element. [5] The phosphor particle according to [4], wherein the Mg content in the coating portion is 1.0 to 8.0 mol % based on the total amount of elements contained in the coating portion. [6] A phosphor powder comprising the phosphor particle according to any one of [1] to [5]. [7] The phosphor powder according to [6], wherein the phosphor powder contains, as constituent elements, Mn, Eu, Mg, Al, O, and N, and the Mn content is 0.2 to 3.0 mol %, the Eu content is 0.1 to 1.2 mol %, the Mg content is 5.0 to 10.5 mol %, the Al content is 28 to 36 mol %, the O content is 51 to 57 mol %, and the N content is 1 to 6 mol %, based on the total content of Mn, Eu, Mg, Al, O, and N in the phosphor powder. [8] A lighting device comprising a light emitting source and a phosphor, wherein the light emitting source emits light having a wavelength of 250 nm or more and 470 nm or less, and the phosphor comprises the phosphor particle according to any of [1] to [5], or the phosphor powder according to [6] or [7]. [9] An image display device comprising an excitation source and a phosphor, wherein the phosphor comprises the phosphor particles according to any one of [1] to [5], or the phosphor powder according to [6] or [7].

[0007] According to the present disclosure, it is possible to provide a γ-AlON-containing phosphor powder with excellent internal quantum efficiency.

[0008] FIG. 1 is a schematic cross-sectional view showing phosphor particles according to one embodiment. FIG. 2 is a schematic cross-sectional view showing a lighting fixture according to one embodiment. FIG. 3 is (a) an SEM image and (b) to (f) EDS mapping images of phosphor particles of Comparative Example 1. FIG. 4 is (a) an SEM image and (b) to (f) EDS mapping images of phosphor particles of Example 1. FIG. 5 shows the emission spectrum and excitation spectrum of the phosphor powder of Example 1.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content. In the description, the same elements or elements having the same functions will be designated by the same reference numerals, and redundant description will be omitted in some cases. The dimensional ratios of each element are not limited to those shown in the drawings.

[0010] Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When multiple substances corresponding to each component are contained, the content of each component means the total amount of the multiple substances unless otherwise specified. In this specification, the "steps" may be steps independent of each other or steps performed simultaneously.

[0011] One embodiment of the present disclosure is a phosphor particle that includes Mn and Eu and contains γ-AlON, and that includes a core portion and a coating portion that coats at least a portion of the surface of the core portion and has an Eu content that is greater than the Eu content in the core portion.

[0012] In phosphor particles containing Eu and γ-AlON, Eu may be unevenly distributed due to the generation of a different phase (a phase other than γ-AlON) during production, etc. The present inventors have discovered that by providing phosphor particles containing Mn and Eu and containing γ-AlON with a structure including a core portion and a coating portion that coats at least a portion of the surface of the core portion and has a higher Eu content than the Eu content in the core portion, the internal quantum efficiency of a phosphor powder containing the phosphor particles can be improved.

[0013] Although the reason for this is unclear, the inventors believe that the phase with a high Eu content that is generated during the production of phosphor particles containing γ-AlON is involved in the absorption and emission of excitation light. Conventionally, even if a different phase occurs in phosphor particles containing γ-AlON, it has been thought that this does not contribute to fluorescence. However, the inventors presume that the absorption and emission of excitation light occur in the phase with a high Eu content that is generated during the production of phosphor particles containing γ-AlON.

[0014] The fact that the phase with a high Eu content is formed to cover the core portion means that the phase was able to grow while suppressing the occurrence of defects by using the core portion's structure (particularly the γ-AlON structure) as a base, which can contribute to improving the efficiency of converting the energy of light absorbed by the phase into luminescence. Thus, the specific structure of phosphor particles containing Eu and γ-AlON is thought to improve the efficiency of utilizing the energy of excitation light, resulting in excellent internal quantum efficiency of phosphor powders containing such phosphor particles. Furthermore, the presence of a phase with a high Eu content in the coating portion (i.e., the surface of the particles) can also contribute to improving the absorption rate of excitation light by the phase. Therefore, the specific structure of phosphor particles is thought to improve the absorption rate of excitation light of phosphor powders containing the phosphor particles.

[0015] In this specification, unless otherwise specified, the properties of phosphor particles and the core and coating portions of phosphor particles (such as the content of each element in the core and coating portions) are evaluated by the following method. First, phosphor particles are mixed with a curable resin (e.g., a two-component thermosetting epoxy resin), and the resin is cured to obtain a cured product. Next, any location of the cured product is cut to prepare a cross-sectional sample. Here, the cutting can be performed, for example, by broad ion beam processing using an ion milling device. The obtained cross-section is observed using an SEM. Furthermore, in an SEM image of the phosphor particle, a single enclosed portion surrounded by resin (in other words, a portion separated from other portions by resin) is determined to be a single phosphor particle (or a portion corresponding to a single phosphor particle).

[0016] Fig. 1 is a schematic cross-sectional view of a phosphor particle according to one embodiment, cut along a plane passing through the center of the phosphor particle. The phosphor particle 1 shown in Fig. 1 includes a core portion 2 and a coating portion 3 that covers at least a portion of the surface of the core portion 2. For example, the area of ​​the coating portion 3 in the phosphor particle 1 may be smaller than the area of ​​the core portion 2. The coating portion 3 may be formed as a layer that covers at least a portion of the surface of the core portion 2.

[0017] 1 shows an example in which the coating 3 uniformly covers the entire surface of the core 2. From the viewpoint of improving the utilization efficiency of excitation light, the coating 3 does not need to be a uniform layer, and the coating 3 may cover only a portion of the core 2. In the phosphor particle 1, the coating 3 may exist as one unified portion, or may be separated into two or more portions. In other words, a portion of the surface of the core 2 may be exposed and not covered by the coating 3.

[0018] Although the phosphor particles 1 are spherical in FIG. 1, they are not limited to being perfectly spherical, and may be in the form of an approximately spherical particle, a flake (for example, a scale or plate), or the like.

[0019] The phosphor particle 1 contains γ-AlON. In this specification, γ-AlON refers to a crystal having a cubic spinel-type crystal structure, and may include AlON crystal, an AlON solid solution crystal (a crystal in which the oxygen / nitrogen ratio is changed or other elements are added while maintaining the AlON crystal structure), and a crystal having the same crystal structure as AlON as the host crystal. For example, a compound having a spinel structure and containing lattice defects and composed of Al, Mg, O, and N elements is included in γ-AlON. γ-AlON that does not contain an activator element is particularly called non-doped γ-AlON.

[0020] The phosphor particle 1 contains Mn and Eu as constituent elements. Furthermore, since the phosphor particle 1 contains γ-AlON, it also contains Al, O, and N as constituent elements. The phosphor particle 1 may further contain at least one element of Mg and Zn (hereinafter also referred to as "A") as a constituent element. The phosphor particle 1 contains, for example, Mn, Eu, Mg, Al, O, and N as constituent elements.

[0021] The Eu content in the core portion 2 is lower than the Eu content in the coating portion 3. In this specification, the content of a specific element (e.g., Eu) in the core portion 2 and the coating portion 3 refers to the amount (molar ratio) of the specific element based on the total amount of elements contained in the core portion 2 and the coating portion 3, respectively. The content of a specific element (e.g., Eu) is determined by performing EDS point analysis at any four or more points corresponding to the core portion 2 and the coating portion 3 in an SEM image of the phosphor particle 1 to determine the content of the specific element at each point and taking the arithmetic average of the four or more values. The core portion 2 may or may not contain Eu as a constituent element. The Eu content (molar ratio) in the core portion 2 is preferably less than 1.0 mol%, more preferably 0.0 mol%, based on the total amount of elements contained in the core portion 2, and may be below the detection limit.

[0022] The core 2 contains, for example, Al, O, and N as constituent elements. The core 2 may further contain the above-mentioned A, and in particular may contain Mg. The core 2 may further contain Mn as a constituent element. The core 2 preferably contains Mn, Mg, Al, O, and N as constituent elements.

[0023] The Al content (molar ratio) in the core portion 2 may be 15.0 mol% or more, 20.0 mol% or more, 25.0 mol% or more, or 28.0 mol% or more, based on the total amount of elements contained in the core portion 2. The Al content in the core portion 2 may be 50.0 mol% or less, 40.0 mol% or less, 35.0 mol% or less, or 32.0 mol% or less, based on the total amount of elements contained in the core portion 2.

[0024] The O content (molar ratio) in the core 2 may be 30.0 mol% or more, 40.0 mol% or more, 45.0 mol% or more, or 50.0 mol% or more, based on the total amount of elements contained in the core 2. The O content may be 80.0 mol% or less, 70.0 mol% or less, 65.0 mol% or less, or 60.0 mol% or less, based on the total amount of elements contained in the core 2.

[0025] The N content (molar ratio) in the core 2 may be 1.5 mol% or more, 2.0 mol% or more, 2.2 mol% or more, or 2.5 mol% or more, based on the total amount of elements contained in the core 2. The N content may be 10.0 mol% or less, 8.0 mol% or less, 5.0 mol% or less, or 4.0 mol% or less, based on the total amount of elements contained in the core 2.

[0026] The Mg content (molar ratio) in the core 2 may be 3.0 mol% or more, 5.0 mol% or more, 6.0 mol% or more, or 7.0 mol% or more, based on the total amount of elements contained in the core 2. The Mg content may be 15.0 mol% or less, 13.0 mol% or less, 11.0 mol% or less, or 10.0 mol% or less, based on the total amount of elements contained in the core 2.

[0027] The Mn content (molar ratio) in the core 2 may be 0.1 mol % or more, 0.5 mol % or more, 1.0 mol % or more, or 1.3 mol % or more, based on the total amount of elements contained in the core 2. The Mn content may be 5.0 mol % or less, 3.0 mol % or less, 2.5 mol % or less, or 2.0 mol % or less, based on the total amount of elements contained in the core 2.

[0028] The Eu content in the coating portion 3 is greater than the Eu content in the core portion 2. The Eu content (molar ratio) in the coating portion 3 may be 1.0 mol % or more based on the total amount of elements contained in the coating portion 3. Furthermore, the Eu content may be 10.0 mol % or less, 8.0 mol % or less, 6.0 mol % or less, 4.0 mol % or less, 3.0 mol % or less, or 2.0 mol % or less based on the total amount of elements contained in the coating portion 3. The Eu content (molar ratio) in the coating portion 3 may be, for example, 1.0 to 6.0 mol % based on the total amount of elements contained in the coating portion 3.

[0029] The coating portion 3 contains, for example, Eu, Al, and O as constituent elements. The coating portion 3 may further contain at least one of N and Mn as constituent elements. The coating portion 3 may further contain A, and in particular may contain Mg. The coating portion 3 may contain Eu, Mn, Mg, Al, and O as constituent elements, or may contain Eu, Mn, Mg, Al, O, and N.

[0030] The Al content (molar ratio) in the coating portion 3 may be 20.0 mol% or more, 30.0 mol% or more, 33.0 mol% or more, or 35.0 mol% or more, based on the total amount of elements contained in the coating portion 3. The Al content may be 60.0 mol% or less, 50.0 mol% or less, 45.0 mol% or less, or 40.0 mol% or less, based on the total amount of elements contained in the coating portion 3.

[0031] The O content (molar ratio) in the coating portion 3 may be 30.0 mol% or more, 40.0 mol% or more, 45.0 mol% or more, or 50.0 mol% or more, based on the total amount of elements contained in the coating portion 3. The O content may be 80.0 mol% or less, 70.0 mol% or less, 65.0 mol% or less, or 60.0 mol% or less, based on the total amount of elements contained in the coating portion 3.

[0032] The N content (molar ratio) in the coating portion 3 may be 0.1 mol% or more, 0.3 mol% or more, 0.5 mol% or more, or 0.8 mol% or more, based on the total amount of elements contained in the coating portion 3. The N content may be 5.0 mol% or less, 3.0 mol% or less, 2.0 mol% or less, or 1.5 mol% or less, based on the total amount of elements contained in the coating portion 3.

[0033] From the viewpoint of improving the stability (stability of the crystal structure) of the coating portion 3, the Mg content (molar ratio) in the coating portion 3 may be greater than 0.0 mol%, 0.5 mol% or more, 1.0 mol% or more, 1.5 mol% or more, 2.0 mol% or more, or 2.3 mol% or more, based on the total amount of elements contained in the coating portion 3. The Mg content may be 10.0 mol% or less, 8.0 mol% or less, 5.0 mol% or less, or 3.5 mol% or less, based on the total amount of elements contained in the coating portion 3. The Mg content in the coating portion may be, for example, 1.0 to 8.0 mol% based on the total amount of elements contained in the coating portion 3.

[0034] From the viewpoint of increasing the luminescence intensity (the intensity of green luminescence derived from Mn), the Mn content (molar ratio) in the coating 3 may be more than 0.0 mol%, 0.1 mol% or more, 0.3 mol% or more, 0.5 mol% or more, or 0.8 mol% or more, based on the total amount of elements contained in the coating 3. From the viewpoint of suppressing concentration quenching, the Mn content may be 5.0 mol% or less, 3.0 mol% or less, 2.0 mol% or less, 1.5 mol% or less, or 1.2 mol% or less, based on the total amount of elements contained in the coating 3. The Mn content in the coating may be, for example, 0.3 to 2.0 mol% based on the total amount of elements contained in the coating 3.

[0035] A phosphor powder containing the phosphor particles described above has excellent internal quantum efficiency. Another embodiment of the present disclosure is a phosphor powder containing the phosphor particles described above.

[0036] The phosphor powder contains, as constituent elements, Mn, Eu, Al, O, and N. The phosphor powder may further contain the above-mentioned A. The phosphor powder preferably contains, as constituent elements, Mn, Eu, Mg, Al, O, and N.

[0037] The Mn content may be 0.2 mol% or more, 0.3 mol% or more, or 0.4 mol% or more based on the total content of Mn, Eu, A, Al, O, and N in the phosphor powder (hereinafter also referred to as "the total content of the above constituent elements"). Furthermore, the Mn content may be 3.0 mol% or less, 2.8 mol% or less, or 2.6 mol% or less based on the total content of the above constituent elements in the phosphor powder. The Mn, Eu, A, and Al contents in the phosphor powder are determined by ICP optical emission spectroscopy analysis using a multi-type ICP optical emission spectroscopy analyzer. Furthermore, the O and N contents are determined by analyzing the oxygen and nitrogen amounts using an oxygen / nitrogen analyzer.

[0038] The Eu content may be 0.1 mol% or more, 0.2 mol% or more, or 0.3 mol% or more based on the total content of the above-mentioned constituent elements in the phosphor powder, and may be 1.2 mol% or less, 1.1 mol% or less, or 1.0 mol% or less based on the total content of the above-mentioned constituent elements in the phosphor powder.

[0039] The content of A may be 5.0 mol% or more, 5.2 mol% or more, or 5.4 mol% or more based on the total content of the above-mentioned constituent elements in the phosphor powder, and may be 10.5 mol% or less, 10.0 mol% or less, or 9.5 mol% or less based on the total content of the above-mentioned constituent elements in the phosphor powder.

[0040] The Al content may be 28 mol% or more, 29 mol% or more, or 30 mol% or more based on the total content of the above-mentioned constituent elements in the phosphor powder, and may be 36 mol% or less, 35 mol% or less, or 34 mol% or less based on the total content of the above-mentioned constituent elements in the phosphor powder.

[0041] The O content may be 51 mol% or more, 52 mol% or more, or 53 mol% or more based on the total content of the above-mentioned constituent elements in the phosphor powder, and may be 57 mol% or less, 56 mol% or less, or 55 mol% or less based on the total content of the above-mentioned constituent elements in the phosphor powder.

[0042] The N content may be 1 mol% or more, 1.5 mol% or more, 2 mol% or more, or 3 mol% or more based on the total content of the above-mentioned constituent elements in the phosphor powder, and may be 6 mol% or less, 5 mol% or less, or 4 mol% or less based on the total content of the above-mentioned constituent elements in the phosphor powder.

[0043] For example, in the phosphor powder, based on the total content of Mn, Eu, A, Al, O, and N in the phosphor powder, the Mn content may be 0.2 to 3.0 mol%, the Eu content may be 0.1 to 1.2 mol%, the A content may be 5.0 to 10.5 mol%, the Al content may be 28 to 36 mol%, the O content may be 51 to 57 mol%, and the N content may be 1 to 6 mol%.

[0044] The phosphor powder contains γ-AlON. The phosphor powder may contain γ-AlON as a primary crystal. The content of γ-AlON in the phosphor powder can be confirmed by powder X-ray diffraction measurement. The phosphor powder may contain a different phase other than γ-AlON.

[0045] An example of a heterophase is one having diffraction lines in the region of a diffraction angle (2θ) of 33.3 to 33.8° in the powder X-ray diffraction pattern of the phosphor powder. In this specification, the powder X-ray diffraction pattern means one obtained by a powder X-ray diffraction method using CuKα radiation under conditions of 25°C. The phosphor powder may have diffraction lines in the region of a diffraction angle (2θ) of 33.3 to 33.8° in the powder X-ray diffraction pattern of the phosphor powder.

[0046] In the powder X-ray diffraction pattern of the phosphor powder, the ratio of the maximum diffraction ray intensity in a region where the diffraction angle (2θ) is 33.3 to 33.8° relative to the diffraction ray intensity of the (311) plane of γ-AlON may be more than 0%, 1% or more, 3% or more, or 5% or more. The ratio of the maximum diffraction ray intensity in this region may be, for example, 40% or less.

[0047] The phosphor powder may have diffraction lines in at least one of the regions where the diffraction angle (2θ) is 19.6 to 20.1°, the region where the diffraction angle (2θ) is 26.8 to 27.3°, and the region where the diffraction angle is 35.4 to 35.9° in the powder X-ray diffraction pattern of the phosphor powder. A heterophase having a peak (diffraction line) in the region where the diffraction angle (2θ) is 33.3 to 33.8° may also have diffraction lines in these regions.

[0048] The phosphor powder may have an emission peak within a wavelength range of 500 to 540 nm in the emission spectrum when excited with light having a wavelength of 380 nm. The lower limit of the wavelength range may be, for example, 505 nm or 510 nm. The upper limit of the wavelength range may be, for example, 530 nm or 520 nm. The emission peak wavelength is specifically determined by the method described in the examples of this specification.

[0049] In the emission spectrum when the phosphor powder is excited with light having a wavelength of 380 nm, the half width of the emission peak may be 5 nm or more, 10 nm or more, or 20 nm or more. The half width of the emission peak may be, for example, 80 nm or less, 50 nm or less, 40 nm or less, or 35 nm or less. In this specification, the half width means the full width at half maximum. The half width is specifically determined by the method described in the examples of this specification.

[0050] The chromaticity x of the phosphor powder may be 0.150 or more, or 0.160 or more. The chromaticity x of the phosphor powder may be 0.190 or less, or 0.180 or less. The chromaticity y of the phosphor powder may be 0.600 or more, or 0.610 or more. The chromaticity y of the phosphor powder may be, for example, 0.800 or less. The chromaticity x and chromaticity y of the phosphor powder refer to values ​​determined by the methods described in the examples.

[0051] The phosphor particles and phosphor powder containing the phosphor particles described above can be produced, for example, by a production method including a step of obtaining undoped γ-AlON, a step of obtaining a mixed powder containing undoped γ-AlON, a Mn source, and a Eu source, and a step of heating the mixed powder.

[0052] The non-doped γ-AlON may contain A, Al, O, and N as constituent elements. A may be Mg. The non-doped γ-AlON may contain A, Al, O, and N as constituent elements, and based on the total content of A, Al, O, and N in the non-doped γ-AlON, the content of A may be 7.0 to 12.0 mol %, the content of Al may be 30.5 to 37 mol %, the content of O may be 52 to 57 mol %, and the content of N may be 1 to 6 mol %.

[0053] In the step of obtaining non-doped γ-AlON, for example, a raw material composition containing an Al source and, if necessary, an A source (hereinafter also referred to as a "first raw material composition") is fired to obtain non-doped γ-AlON. In the step of obtaining non-doped γ-AlON, non-doped γ-AlON (commercially available product) may be obtained, if possible.

[0054] The Al source refers to a compound or simple substance containing aluminum as a constituent element. In this specification, a compound containing aluminum as a constituent element is also referred to as an aluminum compound. The aluminum compound may be any of a nitride (e.g., aluminum nitride), an oxide (e.g., aluminum oxide), an oxynitride, and a hydroxide. The Al source preferably contains at least one of a nitride and an oxide, and more preferably contains both a nitride and an oxide.

[0055] The A source is at least one of an Mg source and a Zn source. The Mg source refers to a compound or simple substance containing magnesium as a constituent element, and the Zn source refers to a compound or simple substance containing zinc as a constituent element. In this specification, a compound containing magnesium as a constituent element is also referred to as a magnesium compound, and a compound containing zinc as a constituent element is also referred to as a zinc compound. The magnesium compound and the zinc compound may each be any of a halide, nitride, oxide, oxynitride, carbonate, and hydroxide.

[0056] Examples of magnesium compounds include magnesium oxide, magnesium carbonate, and magnesium nitride. Examples of zinc compounds include zinc oxide.

[0057] At least one of the Al source and the A source may be a nitride. The nitride may also be referred to as an N source because it contains nitrogen, which is a constituent element of non-doped γ-AlON. At least one of the A source and the Al source may be an oxide. The oxide may also be referred to as an O source because it contains oxygen, which is a constituent element of non-doped γ-AlON.

[0058] The first raw material composition can be prepared, for example, by weighing and mixing each compound or element. The compounding ratio of each component is designed to match the composition of the phosphor particles and phosphor powder. For example, the composition of the first raw material composition may be designed so that, based on the total content of Al, Mg, O, and N in undoped γ-AlON, the Al content is 30 to 37 mol %, the Mg content is 5 to 12 mol %, the O content is 52 to 57 mol %, and the N content is 1 to 6 mol %.

[0059] For mixing, a dry mixing method or a wet mixing method may be used. The dry mixing method is also called a dry blending method, and may be, for example, a method in which the components are mixed using a V-type mixer or the like. The wet mixing method may be, for example, a method in which a solvent or dispersant such as water is added to prepare a solution or slurry, the components are mixed, and then the solvent or dispersant is removed. Alternatively, the compounds may be weighed, mixed, and then the particle size adjusted to be used as the first raw material composition. The particle size can be adjusted, for example, by sieving.

[0060] The firing temperature of the first raw material composition may be 1500°C or higher, 1600°C or higher, 1700°C or higher, or 1750°C or higher, from the viewpoint of promoting grain growth of the γ-AlON main crystal phase. Furthermore, the firing temperature of the first raw material composition may be 2000°C or lower, 1900°C or lower, 1850°C or lower, or 1800°C or lower, from the viewpoint of sufficiently suppressing decomposition of the γ-AlON main crystal phase. The firing temperature of the raw material composition can be adjusted depending on the type (particle size, etc.) of the raw material compound or simple substance, and may be, for example, 1600 to 2000°C, 1650 to 1850°C, or 1650 to 1800°C.

[0061] The firing time of the first raw material composition may be 1 hour or more, 2 hours or more, or 3 hours or more from the viewpoint of promoting the growth of γ-AlON primary particles, and may be 10 hours or less, 7 hours or less, or 5 hours or less from the viewpoint of economy.

[0062] The firing of the first raw material composition may be carried out in an atmosphere containing at least one selected from the group consisting of rare gases such as helium and argon, and nitrogen gas. The firing of the first raw material composition may be carried out, for example, in a nitrogen gas atmosphere. The nitrogen gas atmosphere may be at atmospheric pressure. The firing may also be carried out, for example, in a pressurized atmosphere. When the firing is carried out in a pressurized atmosphere, the pressure may be 0.01 MPaG or more, 0.1 MPaG or more, 0.3 MPaG or more, or 0.5 MPaG or more. The pressure may be 50 MPaG or less, 30 MPaG or less, 10 MPaG or less, 5 MPaG or less, or 1 MPaG or less. The nitrogen gas atmosphere may be at atmospheric pressure, but heating under conditions of high nitrogen pressure makes it easier to suppress decomposition of the produced γ-AlON at high temperatures.

[0063] The fired product obtained by the above method may be used as is as the non-doped γ-AlON, or may be used after adjusting the particle size, which can be adjusted by, for example, crushing (coarse crushing) using a stamp mill or the like, pulverizing using a jet mill or the like, or sieving using a vibrating sieve or the like.

[0064] In the process of obtaining a mixed powder containing non-doped γ-AlON, a Mn source, and an Eu source, for example, the non-doped γ-AlON, the Mn source, and the Eu source are each weighed and mixed to obtain a mixed powder (hereinafter also referred to as the "second raw material composition"). In conventional γ-AlON phosphors, the formation of γ-AlON as a host crystal and the introduction of an activator element are typically performed simultaneously. In the above example of the method for producing a phosphor powder according to the present disclosure, a method is employed in which a Mn source and an Eu source, which are sources of the activator element, are mixed with previously obtained γ-AlON and heated. By employing such a process, it is possible to form phosphor particles having a coating portion with a relatively high Eu content, as described above.

[0065] In the above manufacturing method, both the Mn source and the Eu source are mixed with the previously obtained γ-AlON, and in the manufactured phosphor particles, the Eu content may be higher in the coating portion than in the core portion, while the Mn content may be higher in the core portion than in the coating portion. ２＋ The ionic radius of the tetrahedral Al atoms present in γ-AlON is ３＋ Since the ionic radius is similar to that of Mn ２＋ is the Al ３＋ While it is easy to substitute and dissolve in Eu ２＋ This is thought to be because the ionic radius of is large and it is difficult to form a solid solution in γ-AlON.

[0066] The Mn source refers to a compound or element containing manganese as a constituent element. In this specification, a compound containing manganese as a constituent element is also referred to as a manganese compound. Examples of manganese compounds include manganese oxides (e.g., manganese monoxide and manganese dioxide), manganese carbonates (manganese carbonate), manganese hydroxides (manganese hydroxide), manganese sulfides (manganese sulfide), and manganese halides (manganese halides). Examples of manganese halides include manganese fluoride, manganese chloride, manganese bromide, and manganese iodide. In these compounds, the valence of manganese may be, for example, divalent or tetravalent. The manganese compound may be, for example, one or more selected from the group consisting of manganese oxides and halides. The manganese compound preferably includes manganese oxide.

[0067] The Eu source refers to a compound or simple substance containing europium as a constituent element. In this specification, a compound containing europium as a constituent element is also referred to as a europium compound. Examples of europium compounds include europium oxide (europium oxide), europium hydroxide (europium hydroxide), europium nitride (europium nitride), europium sulfide (europium sulfide), and europium halides (europium halides). Examples of europium halides include europium fluoride, europium chloride, europium bromide, and europium iodide. In these compounds, the valence of europium may be trivalent or divalent. The europium compound may be, for example, one or more selected from the group consisting of europium oxide, nitride, and halide. The compound of europium preferably comprises europium oxide.

[0068] The compounding ratio of each component is designed according to the composition of the phosphor particles and phosphor powder. The mixing can be performed, for example, by the dry mixing method or the wet mixing method described above. Alternatively, each compound may be weighed, mixed, and then deagglomerated to be used as the second raw material composition. Deagglomeration can be performed, for example, by forced sieving.

[0069] The amount of the Eu source in the second raw material composition may be 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, or 2.5 parts by mass or more, relative to 100 parts by mass of the non-doped γ-AlON. The amount of the Eu source in the second raw material composition may be 10 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, or 5 parts by mass or less, relative to 100 parts by mass of the non-doped γ-AlON. By adjusting the amount of the Eu source in the second raw material composition, it is possible to adjust the amount (area ratio) of the coating portion in the produced phosphor particles.

[0070] The amount of the Mn source in the second raw material composition may be 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more per 100 parts by mass of the non-doped γ-AlON. The amount of the Mn source in the second raw material composition may be 10 parts by mass or less, 8 parts by mass or less, or 5 parts by mass or less per 100 parts by mass of the non-doped γ-AlON.

[0071] In the step of heating the mixed powder (second raw material composition), the second raw material composition is heated (fired), for example, in an electric furnace. This produces the above-described phosphor particles and phosphor powder containing the same. The heating temperature of the second raw material composition may be 1300°C or higher, 1400°C or higher, 1500°C or higher, or 1550°C or higher, from the viewpoint of further increasing the emission peak intensity of the phosphor powder. The heating temperature of the second raw material composition may be 1800°C or lower, 1700°C or lower, or 1650°C or lower, from the viewpoint of suppressing phosphor powder sintering and further reducing the particle size distribution span value. The firing temperature of the raw material composition may be, for example, 1300 to 1800°C, 1400 to 1700°C, or 1500 to 1650°C.

[0072] In the step of heating the mixed powder, the heating time may be 1 hour or more, 2 hours or more, or 3 hours or more from the viewpoint of further increasing the emission peak intensity of the phosphor powder, and the heating time of the second raw material composition may be 10 hours or less, 7 hours or less, or 5 hours or less from the viewpoint of economy.

[0073] The mixed powder may be heated, for example, in a nitrogen gas atmosphere. The mixed powder may also be heated, for example, in a pressurized atmosphere. When heated in a pressurized atmosphere, the pressure may be 0.01 MPaG or more, 0.1 MPaG or more, 0.3 MPaG or more, or 0.5 MPaG or more. The pressure may be 50 MPaG or less, 30 MPaG or less, 10 MPaG or less, 5 MPaG or less, or 1 MPaG or less. The mixed powder may be heated, for example, in a nitrogen gas atmosphere at atmospheric pressure, or in a pressurized nitrogen gas atmosphere. The pressure may be the same as the pressure used during firing of the first raw material composition. The nitrogen gas atmosphere may be atmospheric pressure, but heating under conditions of high nitrogen pressure makes it easier to suppress decomposition of the produced γ-AlON at high temperatures.

[0074] The manufacturing method according to one example may further include other steps in addition to the steps of obtaining undoped γ-AlON, obtaining a mixed powder containing undoped γ-AlON, a Mn source, and an Eu source, and heating the mixed powder. An example of the other step is a step of classifying a heat-treated product obtained by heating the mixed powder (classification step).

[0075] The classification may be, for example, dry classification or wet classification. An example of dry classification is sieving using a vibrating sieve. An example of wet classification is elutriation classification.

[0076] The γ-AlON-containing phosphor particles and phosphor powders described above may be used alone or in combination with other phosphors (phosphor particles, phosphor powders, etc.). The γ-AlON-containing phosphor particles and phosphor powders containing them have excellent internal quantum efficiency and are therefore suitable for use in, for example, light-emitting devices or lighting fixtures such as LED lights, and image display devices. The γ-AlON-containing phosphor particles and phosphor powders containing them can also be used by dispersing them in, for example, a curable resin. Examples of the curable resin that can be used include resins used as sealing resins for light-emitting devices, etc.

[0077] One embodiment of the present disclosure is a lighting fixture including a light emitting source and a phosphor. The phosphor includes the above-described γ-AlON-containing phosphor particles or phosphor powder. In the lighting fixture, the phosphor may be excited by light emitted by the light emitting source (hereinafter also referred to as "excitation light") and emit light. More specifically, the phosphor may absorb a portion of the excitation light emitted by the light emitting source and emit light with a wavelength longer than the wavelength of the excitation light.

[0078] In the lighting fixture, the excitation light may be light with a wavelength of 100 nm or more, 190 nm or more, 250 nm or more, or 330 nm or more, or may be light with a wavelength of 470 nm or less, or 380 nm or less. Examples of the luminescence source include an ultraviolet (or purple) LED light-emitting element and an ultraviolet (or purple) LD light-emitting element. The luminescence source may be, for example, an ultraviolet or purple LED light-emitting element or an ultraviolet or purple LD light-emitting element that emits light (excitation light) with a wavelength of 250 nm or more and 470 nm or less, or 330 nm or more and 470 nm or less. Examples of these light-emitting elements include those made of nitride semiconductors such as GaN and InGaN. In these light-emitting elements, a luminescence source that emits light of a predetermined wavelength can be obtained by adjusting the composition of the nitride semiconductor.

[0079] Examples of lighting fixtures include LED lighting fixtures and fluorescent lamps. LED lighting fixtures can be manufactured using the above-mentioned γ-AlON-containing phosphor particles or phosphor powder by known methods such as those described in JP-A-5-152609, JP-A-7-99345, and Japanese Patent No. 2927279.

[0080] In the lighting fixture, the above-described γ-AlON-containing phosphor particles or phosphor powder may be used alone as the phosphor, or may be used in combination with a phosphor having other light-emitting properties. The above-described γ-AlON-containing phosphor particles or phosphor powder usually emits green light derived from Mn and can be used as a green phosphor. By using the above-described γ-AlON-containing phosphor particles or phosphor powder in combination with a phosphor having other light-emitting properties, a lighting fixture that emits a desired color can be constructed.

[0081] In one example of a lighting fixture, an ultraviolet LED or LD light-emitting element that emits excitation light with a wavelength of 330 nm or more and 470 nm or less may be used as the light source, and a yellow phosphor that absorbs part of the excitation light and emits light with a wavelength of 550 nm or more and 600 nm or less and a γ-AlON-containing phosphor particle or phosphor powder that absorbs part of the excitation light and emits green light may be used as the phosphor. In this case, when the excitation light (ultraviolet light) emitted by the LED or LD light-emitting element is irradiated onto the phosphor, two colors of light, green and yellow, are emitted, and white light is obtained by mixing these two colors of light. Here, an example of a yellow phosphor is α-sialon:Eu described in JP 2002-363554 A. ２＋ and (Y, Gd) described in JP-A-10-242513. ３ (Al, Ga) ５ O １２ : Ce can be mentioned.

[0082] In another example, an ultraviolet LED or LD light-emitting element that emits excitation light with a wavelength of 330 nm or more and 470 nm or less may be used as the light source, and the phosphors may include a blue phosphor that absorbs part of the excitation light and emits light with a wavelength of 430 nm or more and 500 nm or less, a red phosphor that absorbs part of the excitation light and emits light with a wavelength of 600 nm or more and 700 nm or less, and γ-AlON-containing phosphor particles or phosphor powder that absorbs part of the excitation light and emits green light. In this case, when the phosphor is irradiated with excitation light (ultraviolet light) emitted by the LED or LD light-emitting element, three colors of light, red, green, and blue, are emitted, and white light is obtained by mixing these three colors of light. Here, an example of a blue phosphor is BaMgAl １０ O １７ :Eu ２＋ An example of a red phosphor is CaSiAlN described in International Publication No. 2005 / 052087. ３ :Eu ２＋ Examples include:

[0083] In another example, an ultraviolet LED or LD light-emitting element that emits excitation light with a wavelength of 330 nm to 470 nm may be used as the light source, and the phosphors may include a blue phosphor that absorbs part of the excitation light and emits light with a wavelength of 430 nm to 500 nm, a yellow phosphor that absorbs part of the excitation light and emits light with a wavelength of 550 nm to 600 nm, a red phosphor that absorbs part of the excitation light and emits light with a wavelength of 600 nm to 700 nm, and γ-AlON-containing phosphor particles or phosphor powder that absorbs part of the excitation light and emits green light. In this case, when the phosphor is irradiated with excitation light (ultraviolet light) emitted by the LED or LD light-emitting element, four colors of light, blue, green, yellow, and red, are emitted, and these four colors of light are mixed to obtain white or reddish warm white light. Here, an example of a blue phosphor is BaMgAl １０ O １７ :Eu ２＋ An example of a yellow phosphor is α-sialon:Eu ２＋ and (Y, Gd) described in JP-A-10-242513. ３ (Al, Ga) ５ O １２ : Ce, and an example of a red phosphor is CaSiAlN described in WO 2005 / 052087. ３ :Eu ２＋ Examples include:

[0084] It should be noted that the combination of phosphors in the lighting fixture is not limited to the above, and for example, the above-mentioned γ-AlON-containing phosphor particles or phosphor powder, the above-mentioned yellow phosphor, and the above-mentioned blue phosphor may be combined as the phosphor.

[0085] FIG. 2 is a schematic cross-sectional view showing a lighting device according to one embodiment. The lighting device 10 shown in FIG. 2 includes a container 11, a light source 12 disposed inside the container 11, and a resin 13 disposed inside the container 11 and sealing the light source 12. A phosphor 14 is dispersed in the resin 13, and the phosphor 14 includes the above-described γ-AlON-containing phosphor particles or phosphor powder. The light source 12 is connected to a conductive terminal 15 and also to a conductive terminal 17 via a wire bond 16. A current can be supplied to the light source 12 from outside the container 11 via the conductive terminals 15, 17, and the wire bond 16. By supplying a current to the light source 12 and emitting excitation light from the light source 12, the excitation light excites the phosphor 14, causing it to emit light.

[0086] The light source 12 may be, for example, an ultraviolet LED chip that emits excitation light with a wavelength of 380 nm. The phosphor 14 may be a mixture phosphor composed of γ-AlON-containing phosphor particles or powder and a Ca-α-sialon:Eu yellow phosphor, which absorbs a portion of the excitation light and emits green light. The γ-AlON-containing phosphor particles or powder may be, for example, the phosphor powder of Example 1 described below. In this case, when a current is applied to the conductive terminals 15 and 17 of the lighting fixture 10, the current is supplied to the light source 12 (ultraviolet LED chip) via the wire bond 16, causing the light source 12 to emit excitation light with a wavelength of 380 nm. The excitation light excites the γ-AlON-containing phosphor particles or powder and the yellow phosphor that make up the phosphor 14 (mixture phosphor), causing them to emit green and yellow light, respectively. As a result of these two colors of light being mixed, the lighting fixture 10 functions as a lighting fixture that emits white light.

[0087] Another embodiment of the present disclosure is an image display device including an excitation source and a phosphor. The phosphor includes the above-described γ-AlON-containing phosphor particles or phosphor powder. In the image display device, the excitation source may emit light (e.g., visible light, ultraviolet light, and X-rays) or an electron beam, and the phosphor may be excited by the light or electron beam to emit light. When the excitation source emits light, the phosphor may absorb a portion of the light emitted by the excitation source (hereinafter also referred to as "excitation light") and emit light with a wavelength longer than the wavelength of the excitation light.

[0088] In the image display device, when the excitation source emits light, the excitation light may be light with a wavelength of 100 nm or more, 190 nm or more, 250 nm or more, or 330 nm or more, or may be light with a wavelength of 470 nm or less, or 380 nm or less. The excitation light may be, for example, vacuum ultraviolet light with a wavelength of 100 to 190 nm, or ultraviolet light with a wavelength of 190 to 380 nm. When the excitation source emits an electron beam, the acceleration voltage of the electron beam may be 10 V or more, and 30 kV or less, or 5 kV or less.

[0089] The above-mentioned γ-AlON-containing phosphor particles and phosphor powder can emit light when excited by vacuum ultraviolet light with a wavelength of 100 to 190 nm, ultraviolet light with a wavelength of 190 to 380 nm, an electron beam, or the like. Therefore, an image display device can be constructed by combining these excitation sources with the above-mentioned γ-AlON-containing phosphor particles or phosphor powder.

[0090] Examples of image display devices include vacuum fluorescent displays (VFDs), field emission displays (FEDs or SEDs), plasma display panels (PDPs), and cathode ray tubes (CRTs). The above-described γ-AlON-containing phosphor particles and phosphor powders can be excellent in excitation efficiency with an electron beam, and therefore can be suitably used in VFDs, FEDs, SEDs, and CRTs that use an excitation source that emits an electron beam at an acceleration voltage of 10 V or more and 30 kV or less. The acceleration voltage of the electron beam emitted by the excitation source may be 10 V or more and 5 kV or less.

[0091] An FED is an image display device that emits light by accelerating electrons emitted from a field emission cathode and colliding them with a phosphor coated on an anode, and is sometimes required to emit light at a low acceleration voltage of 5 kV or less. The above-mentioned γ-AlON-containing phosphor particles and phosphor powder can have excellent excitation efficiency with an electron beam, so that use of the above-mentioned γ-AlON-containing phosphor particles or phosphor powder in an FED can improve the light-emitting performance of the display device.

[0092] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be mutually applied.

[0093] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0094] [Production of phosphor particles] Comparative Example 1: The designed composition was changed to Mg ８．７ Mn １．２ EU ０．４ Al ３２．２ O ５４．９ N ２．６ A raw material composition was obtained by dry blending 71.4 parts by mass of aluminum oxide powder (Advanced Alumina AA-1.5, manufactured by Sumitomo Chemical Co., Ltd.), 5.1 parts by mass of aluminum nitride powder (E grade, manufactured by Tokuyama Corporation), 16.6 parts by mass of magnesium oxide powder (Fujifilm Wako Pure Chemical Industries, Ltd., average particle size: 0.2 μm, purity: 99.9 wt%), 4.0 parts by mass of manganese monoxide powder (Kojundo Chemical Laboratory Co., Ltd., purity: 3N), and 3.0 parts by mass of europium oxide powder (RU type, manufactured by Shin-Etsu Chemical Co., Ltd.) in a pressure setting of 0.72 MPaG using a graphite resistance electric furnace (manufactured by Fuji Radio Industrial Co., Ltd.). The raw material composition was filled into a boron nitride crucible and fired at 1800°C for 4 hours under a nitrogen gas atmosphere of 0.72 MPaG using a graphite resistance electric furnace (manufactured by Fuji Radio Industrial Co., Ltd.). The obtained fired product was pulverized using a jet mill (PSM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd., sample feed rate: 30 g / min, pulverization pressure: 0.5 MPa) and then passed through a vibrating sieve (mesh opening: 45 μm). The powder that passed through the vibrating sieve was used as the phosphor powder of Comparative Example 1.

[0095] Example 1: The designed composition (the designed composition of the first fired product) was ９ Al ３３．３ O ５５ N ２．７ First, 76.7 parts by mass of aluminum oxide powder (Advanced Alumina AA-5, manufactured by Sumitomo Chemical Co., Ltd.), 5.4 parts by mass of aluminum nitride powder (E grade, manufactured by Tokuyama Corporation), and 17.8 parts by mass of magnesium oxide powder (Fujifilm Wako Pure Chemical Industries, Ltd., average particle size: 0.2 μm, purity: 99.9 wt%) were mixed by dry blending to obtain a first raw material composition. The first raw material composition was filled into a boron nitride crucible and fired at 1800°C for 4 hours in a nitrogen gas atmosphere of 0.72 MPaG using a graphite resistance electric furnace (manufactured by Fuji Radio Kogyo Co., Ltd.), to obtain a first fired product.

[0096] The first fired product was pulverized using a jet mill (PSM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd., sample feed rate: 30 g / min, pulverization pressure: 0.5 MPa) and then passed through a vibrating sieve (mesh size: 45 μm). The powder that passed through the vibrating sieve was collected as non-doped γ-AlON. 93.0 parts by mass of non-doped γ-AlON, 4.0 parts by mass of manganese monoxide powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity: 3N), and 3.0 parts by mass of europium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd., RU type) were wet mixed using a ball mill (solvent: ethanol) to obtain a second raw material composition.

[0097] The second raw material composition was filled into a boron nitride crucible and fired in a graphite resistance electric furnace (manufactured by Fuji Radio Industrial Co., Ltd.) under a nitrogen gas atmosphere of 0.72 MPaG at 1600°C for 4 hours to obtain a second fired product. The second fired product was passed through a vibrating sieve (mesh size: 45 μm), and the powder that passed through the vibrating sieve was used as the phosphor powder of Example 1. The phosphor powder of Example 1 was a phosphor powder containing phosphor particles containing γ-AlON. Furthermore, in the powder X-ray diffraction pattern of the phosphor powder of Example 1 (obtained by powder X-ray diffraction using CuKα radiation at 25°C), diffraction lines were observed in the region of the diffraction angle (2θ) of 33.3 to 33.8°, in addition to the diffraction lines of γ-AlON. The ratio of the maximum diffraction line intensity of the heterophase (diffraction line observed in the region where the diffraction angle (2θ) is 33.3 to 33.8°) to the diffraction line intensity of the (311) plane of γ-AlON was in the range of 5 to 10%.

[0098] Example 2 A phosphor powder of Example 2 was produced in the same manner as in Example 1, except that the aluminum oxide powder was changed to Advanced Alumina AA-1.5 manufactured by Sumitomo Chemical Co., Ltd.

[0099] Example 3 A phosphor powder of Example 3 was produced in the same manner as in Example 2, except that the firing temperature was changed to 1800°C.

[0100] Example 4: The design composition of the first fired product was changed to Mg ７．６ Al ３４．６ O ５４．４ N ３．４ A phosphor powder of Example 4 was prepared in the same manner as in Example 3 except for the above change.

[0101] Example 5: The design composition of the first fired product was changed to Mg １０．３ Al ３２．２ O ５５．５ N ２．１ A phosphor powder of Example 5 was prepared in the same manner as in Example 3 except for changing the above.

[0102] [Evaluation] <Particle Observation> The phosphor particles contained in the phosphor powder of Comparative Example 1 (hereinafter also referred to as "phosphor particles of Comparative Example 1") and the phosphor particles contained in the phosphor powder of Example 1 (hereinafter also referred to as "phosphor particles of Example 1") were each mixed with a two-component thermosetting epoxy resin (G2, manufactured by Gatan Co., Ltd.), degassed under vacuum, poured into an embedding plate, and cured by heating at 110°C. The cured product was subjected to broad ion beam processing (accelerating voltage: 4 kV) using an ion milling device (IM4000PLUS, manufactured by Hitachi High-Tech Corporation) to prepare cross-sectional samples. The cross-sections of the obtained samples were observed using a scanning electron microscope / Regulus SU8220 (SEM), manufactured by Hitachi High-Tech Corporation, to obtain SEM images of the cross-sections of each phosphor particle. An SEM image of the cross-section of the phosphor particle of Comparative Example 1 is shown in FIG. 3(a), and an SEM image of the cross-section of the phosphor particle of Example 1 is shown in FIG. 4(a). In addition, EDS mapping images corresponding to each SEM image were obtained using an EDS detector (Flad Quad, manufactured by Bruker). The EDS mapping images are shown in Figures 3(b) to 3(f) and Figures 4(b) to 4(f). In Figures 3 and 4(b), (c), (d), (e), and (f), respectively, areas where the presence of the target elements O, Al, Mg, Mn, and Eu is greater are shown with higher brightness (whiter), and areas where the presence of each element is lower are shown with lower brightness (blacker).

[0103] As shown in Figures 3(a) and (f), the phosphor particles of Comparative Example 1 had a distorted shape, and although there were particles in which both low and high Eu content portions were present within a single particle, the low and high Eu content portions were irregularly distributed within a single particle, and at least a portion of the low Eu content portion was not covered by a layer of high Eu content portions. Furthermore, among the phosphor particles of Comparative Example 1, particles in which Eu was barely detectable throughout the particle and particles containing Eu with no difference in its content throughout the particle were confirmed. On the other hand, as shown in Figures 4(a) and (f), in the phosphor particles of Example 1, it was confirmed that at least a portion of the core portion with a low Eu content was covered by a coating portion with a high Eu content. Furthermore, in the phosphor particles contained in the phosphor powder of Example 2, it was confirmed that at least a portion of the core portion with a low Eu content was covered by a coating portion with a high Eu content.

[0104] <Content of Each Element> The compositions of the core and coating portions of the phosphor particles contained in each of the phosphor powders of Examples 2 to 5 were examined by EDS point analysis using an EDS detector (X Flash 6, manufactured by Bruker). The content (molar ratio) of each element based on the total amount of elements contained in the core and coating portions is shown in Tables 1 to 4 below. The results of Example 2 are shown in Table 1, the results of Example 3 in Table 2, the results of Example 4 in Table 3, and the results of Example 5 in Table 4. The values ​​shown in Tables 1 to 4 are the arithmetic mean values ​​of measurements taken at four points in the core and four points in the coating, respectively.

[0105]

[0106]

[0107]

[0108]

[0109] <Emission characteristics> For the phosphors (phosphor powders) of the comparative examples and examples, the emission spectra were measured at an excitation wavelength of 380 nm using a spectrofluorometer (FP8600) manufactured by JASCO Corporation, and the emission peak wavelength and the half-width of the emission peak were determined. The results are shown in Table 5.

[0110] The emission spectrum and excitation spectrum of the phosphor powder of Example 1 are shown in Figure 5. In Figure 5, the emission spectrum was measured by irradiating the phosphor powder of Example 1 with light of 380 nm to excite the phosphor powder of Example 1. The excitation spectrum was obtained by monitoring the peak wavelength (516.8 nm) of the emission spectrum. Figure 5 confirms that the phosphor powder of Example 1 is efficiently excited by light of wavelengths of 250 nm or more and 470 nm or less, and is a green-emitting phosphor having an emission peak at 516.8 nm.

[0111] From the spectral data of the obtained emission spectrum in the wavelength range of 400 to 780 nm, the x value (chromaticity x) of the CIE chromaticity coordinates and the y value (chromaticity y) of the CIE chromaticity coordinates in the XYZ color system defined in JIS Z 8781-3:2016 "Colorimetry - Part 3: CIE Tristimulus Values" were calculated in accordance with JIS Z 8724:2015 "Methods for measuring color - Light source color," thereby determining the chromaticity x and chromaticity y. The results are shown in Table 5.

[0112] Furthermore, the phosphors (phosphor powders) of the comparative examples and examples were filled into a concave cell so that the surface was smooth, and the cell was attached to the opening of an integrating sphere. Monochromatic light having a wavelength of 380 nm was split from a Xe lamp, which was the light source, and introduced into the integrating sphere using an optical fiber as excitation light for the phosphor (phosphor powder). This monochromatic excitation light was irradiated onto the phosphor (phosphor powder) to be measured, and the emission spectrum was measured. A spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., product name: MCPD-7000) was used for the measurement.

[0113] The number of reflected excitation light photons (Qref) and the number of fluorescent photons (Qem) were calculated from the obtained emission spectrum data. The number of reflected excitation light photons was calculated in the same wavelength range as when calculating the number of excitation light photons, and the number of fluorescent photons was calculated in the range of 395 to 800 nm. Using the same device, a standard reflector with a reflectance of 99% (Spectralon (registered trademark), manufactured by Labsphere) was attached to the opening of the integrating sphere to measure the spectrum of excitation light with a wavelength of 380 nm. At this time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 370 to 395 nm.

[0114] From the above calculation results, the internal quantum efficiency and excitation light absorptance at 380 nm of the phosphor (phosphor powder) to be measured were calculated based on the following formulas. Table 5 shows the relative values ​​of the internal quantum efficiency and excitation light absorptance when the values ​​of the internal quantum efficiency and excitation light absorptance of the phosphor (phosphor powder) of Comparative Example 1 are each set to 100. 380 nm excitation light absorptance = ((Qex - Qref) / Qex) x 100 Internal quantum efficiency = (Qem / (Qex - Qref)) x 100

[0115] The emission peak wavelength, chromaticity x, and chromaticity y of a standard sample of a Eu-activated β-sialon phosphor (manufactured by Sialon Corporation, Standard Phosphor Green, Lot No. NSG1301) were measured in accordance with the above-mentioned measurement method. The emission peak wavelength was 541.0 nm, the half-width of the emission peak was 55 nm, the chromaticity x was 0.363, and the chromaticity y was 0.619.

[0116] The measured values ​​of the luminous characteristics and the chromaticity x and chromaticity y may vary if the manufacturer, production lot number, etc. of the measuring device changes. Therefore, the values ​​measured by the measurement method described in this specification are used as the various measured values. However, if the manufacturer, production lot number, etc. of the measuring device are changed, the measured values ​​can be corrected using the measured values ​​using the standard sample described above as the reference value.

[0117]

[0118] 1...phosphor particle, 2...core portion, 3...coating portion, 10...lighting device, 11...container, 12...light source, 13...resin, 14...phosphor, 15, 17...conductive terminal, 16...wire bond.

Claims

1. A phosphor particle containing γ-AlON and containing Mn and Eu as constituent elements, the phosphor particle comprising: a core portion; and a coating portion that coats at least a portion of the surface of the core portion, the coating portion having a higher Eu content than the Eu content in the core portion.

2. The phosphor particle according to claim 1, wherein the content of said Eu in said coating portion is 1.0 to 6.0 mol % based on the total amount of elements contained in said coating portion.

3. The phosphor particle according to claim 1, wherein the content of said Mn in said coating portion is 0.3 to 2.0 mol % based on the total amount of elements contained in said coating portion.

4. The phosphor particles according to claim 1, further containing Mg as a constituent element.

5. The phosphor particle according to claim 4, wherein the content of said Mg in said coating portion is 1.0 to 8.0 mol % based on the total amount of elements contained in said coating portion.

6. A phosphor powder comprising the phosphor particles according to any one of claims 1 to 5.

7. The phosphor powder according to claim 6, wherein the phosphor powder contains Mn, Eu, Mg, Al, O, and N as constituent elements, and based on the total content of the Mn, Eu, Mg, Al, O, and N in the phosphor powder, the Mn content is 0.2 to 3.0 mol %, the Eu content is 0.1 to 1.2 mol %, the Mg content is 5.0 to 10.5 mol %, the Al content is 28 to 36 mol %, the O content is 51 to 57 mol %, and the N content is 1 to 6 mol %.

8. A lighting device comprising a light source and a phosphor, wherein the light source emits light having a wavelength of 250 nm or more and 470 nm or less, and the phosphor contains phosphor particles according to any one of claims 1 to 5.

9. A lighting device comprising a light source and a phosphor, wherein the light source emits light having a wavelength of 250 nm or more and 470 nm or less, and the phosphor contains the phosphor powder according to claim 6.

10. An image display device comprising an excitation source and a phosphor, wherein the phosphor contains phosphor particles according to any one of claims 1 to 5.

11. An image display device comprising an excitation source and a phosphor, wherein the phosphor contains the phosphor powder according to claim 6.

Images