Ce-activated alpha sialon phosphor and method for manufacturing the same

Abstract

A Ce-activated α-sialon phosphor having a luminescence peak in a wavelength range of 470 to 525 nm in a luminescence spectrum when excited by light having a wavelength of 405 nm, and a diffuse reflectance of light at the wavelength of the luminescence peak of 86.5% or more.

Description

Technical Field

[0001] This disclosure relates to a Ce-activated α-cylon phosphor and a method for manufacturing the same. Background Technology

[0002] Alpha-type silane (Si-Al-ON) is a solid solution with a structure in which certain elements are infiltrated and dissolved within the lattice of alpha-type silicon nitride, maintaining electroneutrality. It consists of Si-N bonds partially replaced by Al-N or Al-O bonds. By replacing some of the infiltrated solid solution elements with luminescent centers, it emits fluorescence.

[0003] Patent document 1 discloses an α-type silane, which has the general formula: (M1) X (M2) Y (Si, Al) 12 (O, N) 16 (where M1 is one or more elements selected from the group consisting of Li, Mg, Ca, Y and lanthanide metals (excluding La and Ce), and M2 is one or more elements selected from Ce, Pr, Eu, Tb, Yb and Er, and 0.3 < X + Y < 1.5, 0 < Y < 0.7) represents α-type silane, characterized by containing more than 30 ppm and less than 1% fluorine as an impurity.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2005 / 123876 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Phosphors containing α-type silon with Ce as the luminescent center are attracting attention as phosphors emitting fluorescence in the blue to green regions. The purpose of this disclosure is to provide a Ce-activated α-silon phosphor with excellent internal quantum efficiency, and a method for manufacturing a Ce-activated α-silon phosphor with excellent internal quantum efficiency.

[0009] Problem Solving

[0010] The inventors have discovered that by setting the diffuse reflectance of light at the wavelength of the emission peak to a predetermined value or higher, Ce-activated α-cylon can be obtained with improved internal quantum efficiency. Furthermore, the inventors have also discovered that doping Ce-activated α-cylon with an Eu source and then annealing it is an effective means of improving the diffuse reflectance as described above. In other words, the inventors have discovered that by heating Ce-activated α-cylon together with an Eu source, Ce-activated α-cylon phosphors with excellent internal quantum efficiency can be manufactured. This disclosure is based on the above findings.

[0011] This disclosure provides the following [1] to

[12] .

[0012] [1] An α-silicon phosphor activated by Ce has an emission peak in the wavelength range of 470~525nm in the emission spectrum when excited by light with a wavelength of 405nm, and the diffuse reflectance of light at the wavelength of the emission peak is above 86.5%.

[0013] [2] As described in [1], the Ce-activated α-cerone phosphor contains Eu.

[0014] [3] As described in [1] or [2], the Ce-activated α-cylon phosphor contains 0.0001 to 1.5% Eu based on the total mass of the Ce-activated α-cylon phosphor.

[0015] [4] The Ce-activated α-silicon phosphor described in any of [1] to [3] has a half-width of emission peak greater than 100 nm.

[0016] [5] The Ce-activated α-silicon phosphor described in any of [1] to [4] has a luminescence intensity at a wavelength of 580 nm that is less than 45% of the intensity of the luminescence peak.

[0017] [6] The Ce-activated α-silon phosphor described in any of [1] to [5] contains M, Ce, Si, Al, O and N as constituent elements, wherein M is at least one element selected from the group consisting of Li, Ca, Mg, Y and lanthanide elements (excluding La, Ce and Eu), and the content of M is 1 to 4 mol%, the content of Ce is 0.05 to 2 mol%, the content of Si is 25 to 45 mol%, the content of Al is 4 to 12 mol%, the content of O is 0.5 to 5 mol%, and the content of N is 40 to 60 mol, based on the total content of M, Ce, Si, Al, O and N in the Ce-activated α-silon phosphor.

[0018] [7] The Ce-activated α-cylon phosphor described in any of [1] to [6], wherein the Ce-activated α-cylon phosphor contains the α-type cylon represented by the following general formula (1),

[0019] (M a+ x Ce 3+ y Si 12-(m+n) Al (m+n) O n N 16-n (1)

[0020] In general formula (1), M is at least one element selected from the group consisting of Li, Ca, Mg, Y and lanthanides (excluding La, Ce and Eu). When the valence of M is set to a, m = ax + 3y, Ce 3+ Replace M with the following condition: 0.3 ≤ x + y ≤ 2, 0.03 ≤ y ≤ 0.5, 0 ≤ n ≤ m.

[0021] [8] A method for manufacturing Ce-activated α-cylon phosphor, comprising: heating a mixture containing Ce-activated α-cylon and an Eu source at 1200~1500°C to obtain a heat-treated product.

[0022] [9] The manufacturing method described in [8] wherein the content of Eu source in the mixture is 0.1 to 3.0 parts by mass relative to 100 parts by mass of Ce-activated α-cyrone.

[0023]

[10] The manufacturing method described in [8] or [9], wherein the heat treatment is carried out in an atmosphere containing at least one of the group consisting of rare gases and reducing gases.

[0024]

[11] The manufacturing method described in any of [8] to

[10] further includes a step of acid treatment of the heat-treated material.

[0025]

[12] The manufacturing method described in any of [8] to

[11] further includes a step of obtaining Ce-activated α-cylon by calcining a raw material composition containing a Si source, an Al source and a Ce source.

[0026] The effects of the invention

[0027] According to this disclosure, a Ce-activated α-Cylon phosphor with excellent internal quantum efficiency and a method for manufacturing the Ce-activated α-Cylon phosphor with excellent internal quantum efficiency are provided. Attached Figure Description

[0028] Figure 1The emission spectra of the α-silicon phosphors in Examples 1, 2 and Comparative Examples 7, 12 are shown. Detailed Implementation

[0029] The following describes embodiments of this disclosure. However, the following embodiments are merely illustrative and are not intended to limit this disclosure to the following content.

[0030] Unless otherwise specified, the materials illustrated in this specification may be used alone or in combination of two or more. The content of each component in the composition refers to the total amount of the various substances present in the composition, unless otherwise specified. The term "process" in this specification may refer to independent processes or processes performed simultaneously.

[0031] Ce-activated α-cylon phosphor

[0032] One embodiment of this disclosure is a Ce-activated α-cylon phosphor. This Ce-activated α-cylon phosphor will also be referred to as "Ce-activated α-cylon phosphor" below.

[0033] The Ce-activated α-silicon phosphor described above, when excited by light at a wavelength of 405 nm, should have a diffuse reflectance of 86.5% or higher for the wavelength at which the emission peak is located. In cases where multiple peaks are observed in the emission spectrum of the Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm, the peak with the highest intensity is considered the "emission peak" in this specification.

[0034] A high diffuse reflectance, as specified above, indicates fewer defects in the crystals of the Ce-activated α-cylon phosphor that absorb the light emitted by the phosphor. Therefore, Ce-activated α-cylon phosphors with diffuse reflectance exceeding the specified value are considered to have excellent internal quantum efficiency. Historically, achieving a diffuse reflectance of 86.5% or higher for Ce-activated α-cylon phosphors has been challenging. However, after in-depth research, the inventors discovered that by subjecting Ce-activated α-cylon to specific treatments, Ce-activated α-cylon phosphors with high diffuse reflectance can be obtained.

[0035] Ce-activated α-cylon phosphors contain Ce as the luminescent center element. Ce-activated α-cylon phosphors may substantially lack Eu as the luminescent center element, or they may substantially contain only Ce as the luminescent center element. If a Ce-activated α-cylon phosphor substantially lacks Eu as the luminescent center element, it means that no emission peak originating from Eu is observed in the emission spectrum of the Ce-activated α-cylon phosphor when excited by light at a wavelength of 405 nm. Conversely, if a Ce-activated α-cylon phosphor substantially contains only Ce as the luminescent center element, it means that only peaks originating from Ce are observed in the emission spectrum of the Ce-activated α-cylon phosphor when excited by light at a wavelength of 405 nm. For example, if the Ce-activated α-cylon phosphor contains Eu but no emission peak originating from Eu is observed, in this specification, Eu is determined not to be an element included as the luminescent center element.

[0036] Ce-activated α-cylon phosphors may contain M, Ce, Si, Al, O, and N as constituent elements. Here, M is at least one element selected from the group consisting of Li, Ca, Mg, Y, and lanthanides (excluding La, Ce, and Eu). Based on the total content of M, Ce, Si, Al, O, and N in the Ce-activated α-cylon phosphor (hereinafter also referred to as "the total content of the above constituent elements"), the content of M may be 1 mol% or more or 2 mol% or more. Alternatively, based on the total content of the above constituent elements in the Ce-activated α-cylon phosphor, the content of M may be 4 mol% or less or 3 mol% or less. Based on the total content of the above constituent elements in the Ce-activated α-cylon phosphor, the content of Ce may be 0.05 mol% or more or 0.1 mol% or more. In addition, based on the total content of the above-mentioned constituent elements in the Ce-activated α-cylon phosphor, the Ce content can also be less than 2 mol% or less than 1 mol%.

[0037] Based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon phosphor, the Si content can be 25 mol% or more, or 30 mol% or more. Alternatively, based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon phosphor, the Si content can also be 45 mol% or less, or 40 mol% or less. Based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon phosphor, the Al content can be 4 mol% or more, 5 mol% or more, or 6 mol% or more. Alternatively, based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon phosphor, the Al content can also be 12 mol% or less, 10 mol% or less, 9 mol% or less, or 8 mol% or less. The contents of M, Ce, Si, and Al can be determined by analysis using a multi-element ICP-based ICP-based spectroscopy apparatus and according to the ICP-based spectroscopy method.

[0038] Based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon fluorophore, the O content can be 0.5 mol% or more, or 1 mol% or more. Furthermore, based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon fluorophore, the O content can also be 5 mol% or less, or 4 mol% or less. Based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon fluorophore, the N content can be 40 mol% or more, or 45 mol% or more. Furthermore, based on the total content of the aforementioned constituent elements in the Ce-activated α-silicon fluorophore, the N content can also be 60 mol% or less, or 55 mol% or less. The O and N contents are determined by analyzing the oxygen and nitrogen content using an oxygen and nitrogen analyzer.

[0039] For example, in Ce-activated α-cylon phosphors, based on the total content of M, Ce, Si, Al, O, and N in the Ce-activated α-cylon phosphor, the content of M can be 1-4 mol%, Ce can be 0.05-2 mol%, Si can be 25-45 mol%, Al can be 4-12 mol%, O can be 0.5-5 mol%, and N can be 40-60 mol%, or the content of M can be 1-4 mol%, Ce can be 0.05-2 mol%, Si can be 25-45 mol%, Al can be 5-9 mol%, O can be 0.5-5 mol%, and N can be 40-60 mol%.

[0040] Ce-activated α-silicon phosphors may contain a main crystal having the same crystalline structure as α-silicon. Ce-activated α-silicon phosphors may contain heterogeneous phases without prejudice to the intent of this disclosure. In the powder X-ray diffraction pattern of the Ce-activated α-silicon phosphor, the ratio of the intensity of the maximum diffraction line of the heterogeneous phase to the intensity of the diffraction line on the (101) plane may be 10% or less, 5% or less, 3% or less, or 2% or less. In this specification, powder X-ray diffraction pattern refers to a pattern obtained by powder X-ray diffraction using CuKα rays at 25°C. Furthermore, the maximum diffraction line of the heterogeneous phase refers to the diffraction line with the highest diffraction intensity among the diffraction lines not belonging to α-silicon in the powder X-ray diffraction pattern.

[0041] Ce-activated α-cylon phosphors may contain, for example, α-cylons represented by the following general formula (1).

[0042] (M a+ x Ce 3+ y Si 12-(m+n) Al (m+n) O n N16-n (1)

[0043] In general formula (1), M is at least one element selected from the group consisting of Li, Ca, Mg, Y and the lanthanides (excluding La, Ce and Eu). When the valence of M is set to a, m = ax + 3y, Ce 3+ Replace M with the following condition: 0.3 ≤ x + y ≤ 2, 0.03 ≤ y ≤ 0.5, 0 ≤ n ≤ m.

[0044] Ce-activated α-cylon phosphors may contain Ca, or may contain α-cylons with Ca dissolved in solution. In the above general formula (1), M may be Ca, or may be two or more elements selected from the group consisting of Ca and at least one element selected from the group consisting of Li, Mg, Y and lanthanides (excluding La, Ce and Eu). When M is Ca, a=2 in general formula (1). The presence of Ca in Ce-activated α-cylon phosphors can be confirmed by quantitative elemental analysis using an ICP-based luminescence spectrophotometer.

[0045] In general formula (1), x + y can be greater than or equal to 0.4, 0.5, 0.6, or 0.7, and can also be less than or equal to 1.8, 1.5, 1.3, 1.1, 1.0, or 0.9. In general formula (1), y can be greater than or equal to 0.05 or 0.06, and can also be less than or equal to 0.4, 0.3, 0.2, or 0.1. In general formula (1), n ​​can be greater than or equal to 0.01, 0.05, or 0.10, and can be less than m.

[0046] Ce-activated α-cylon phosphor contains α-type cylon as represented by the above general formula (1), which means that in the powder X-ray diffraction pattern of the Ce-activated α-cylon phosphor, the ratio of the maximum diffraction intensity of the heterogeneous phase to the diffraction intensity of the (101) plane is less than 10%, and the content ratio of each constituent element (M, Ce, Si, Al, O and N) calculated by using a multi-element type ICP emission spectrophotometer and based on the analysis of the ICP emission spectrophotometer method and the analysis of the oxygen and nitrogen content using an oxygen and nitrogen analysis device is equal to the ratio shown in general formula (1).

[0047] Ce-activated α-cylon phosphors can be represented, for example, by the general formula (1) above. In this case, M, x+y, y, and n are as described above. The constituent elements and proportions of Ce-activated α-cylon phosphors can be determined by analyzing the oxygen and nitrogen content using an oxygen and nitrogen analyzer and by using a multi-element ICP luminescence spectrophotometer and according to the ICP luminescence spectrophotometric method. The fact that Ce-activated α-cylon phosphors are represented by the general formula (1) above means that when determining the constituent elements and proportions of Ce-activated α-cylon phosphors through the above analysis, the content ratios of Ce, Si, Al, O, N, and M in general formula (1) are equal to the ratios shown in general formula (1), and the content of elements other than the above elements is 1.5% by mass or less.

[0048] Ce-activated α-cylon phosphors may contain Eu. Based on the total mass of the Ce-activated α-cylon phosphors, the Eu content may be 0.0001% by mass (1 ppm) or more, or 0.0002% by mass (2 ppm) or more. Based on the total mass of the Ce-activated α-cylon phosphors, the Eu content may be 5.0% by mass or less, 3.0% by mass or less, or 1.5% by mass or less. The Eu content, based on the total mass of the Ce-activated α-cylon phosphors, may, for example, be 0.0001 to 5.0% by mass, 0.0001 to 3.0% by mass, or 0.0001 to 1.5% by mass. In this specification, the Eu content refers to the content obtained by quantitative elemental analysis using an ICP-based luminescence spectrophotometer. Specifically, the Eu content can be obtained according to the methods described in the examples. In the case of Ce-activated α-cylon phosphor containing Eu as the luminescent center element, the above-mentioned Eu content refers to the total amount of Eu as the luminescent center element and Eu that does not function as the luminescent center element.

[0049] The emission spectrum of a Ce-activated α-silicon phosphor, when excited with light at a wavelength of 405 nm, shows an emission peak at a wavelength of 470–525 nm. The lower limit of this wavelength range can be, for example, 480 nm or 490 nm. The upper limit of this wavelength range can be, for example, 520 nm or 510 nm. This wavelength range corresponds to the range of observable emission peaks when the α-silicon phosphor is activated by Ce, but at least substantially not activated by Eu. Specifically, the emission peak wavelength can be obtained according to the methods described in the embodiments of this specification.

[0050] When a Ce-activated α-silicon phosphor is excited with light at a wavelength of 405 nm, the half-width at half-maximum (WWHM) of the emission peak in its emission spectrum can be 100 nm or more, 101 nm or more, or 102 nm or more. The WWHM can also be, for example, less than 150 nm, less than 130 nm, less than 120 nm, less than 115 nm, or less than 110 nm. Furthermore, in this specification, WWHM refers to the full width at half maximum (FWHM). Specifically, the WWHM can be obtained according to the method described in the embodiments of this specification.

[0051] In the emission spectrum of a Ce-activated α-silicon phosphor excited with light at a wavelength of 405 nm, the ratio of the emission intensity observed at a wavelength of 580 nm to the intensity of the emission peak (the ratio of the emission intensity observed at 580 nm to the intensity of the emission peak, hereinafter also referred to as the "emission intensity ratio") can be less than 90%, less than 70%, less than 60%, less than 50%, less than 45%, less than 40%, less than 35%, or less than 30%. The emission intensity ratio can, for example, be 0% or more or more than 10%. Furthermore, it is considered that in the above emission spectrum, emission from Ce can be observed near 470–525 nm, and emission from Eu can be observed near 580 nm. Therefore, it is considered that, especially in the case where the wavelength of the emission peak is 470–525 nm, the above emission intensity ratio is relatively small, meaning that the amount of Eu included as the emission center element is small relative to the amount of Ce included as the emission center element. Specifically, the emission intensity ratio can be obtained according to the method described in the embodiments of this specification.

[0052] The chromaticity x calculated from the emission spectrum of a Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm can be 0.170 or higher, or 0.180 or higher. Furthermore, the chromaticity x calculated from the emission spectrum of a Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm can be 0.340 or lower, or 0.325 or lower. The chromaticity y calculated from the emission spectrum of a Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm can be 0.270 or higher, or 0.275 or higher. Furthermore, the chromaticity y calculated from the emission spectrum of a Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm can be 0.550 or lower, or 0.545 or lower. The chromaticity x and chromaticity y calculated from the emission spectrum of a Ce-activated α-silicon phosphor excited by light at a wavelength of 405 nm refer to the values ​​obtained according to the method described in the examples.

[0053] When a Ce-activated α-silicon phosphor is excited with light at a wavelength of 405 nm, the diffuse reflectance of the Ce-activated α-silicon phosphor for the wavelength of the emission peak can be 86.5% or higher, 87.0% or higher, or 87.5% or higher. Conversely, when a Ce-activated α-silicon phosphor is excited with light at a wavelength of 405 nm, the diffuse reflectance of the Ce-activated α-silicon phosphor for the wavelength of the emission peak can be, for example, less than 100.0%, less than 95.0%, or less than 90.0%.

[0054] The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 600 nm can be above 85.0%, 88.5%, 89.0%, 90.0%, 91.0%, or 91.5%. A diffuse reflectance within this range for 600 nm indicates a reduction in defects in the phosphor's crystalline structure or the occurrence of heterogeneous phases in non-luminescent components, which helps to further improve the internal and external quantum efficiency of the α-silicon phosphor. The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 600 nm can, for example, be below 100.0%, below 95.0%, or below 93.0%.

[0055] The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 700 nm can be 85.0% or higher, 88.0% or higher, 89.5% or higher, 90.0% or higher, 91.0% or higher, or 91.5% or higher. A diffuse reflectance within this range for 700 nm indicates a reduction in defects in the phosphor's crystalline structure or the occurrence of heterogeneous phases in non-luminescent components, which helps to further improve the internal and external quantum efficiency of the α-silicon phosphor. The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 700 nm can, for example, be 100.0% or lower, 95.0% or lower, or 94.0% or lower.

[0056] The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 800 nm can be 85.0% or higher, 89.0% or higher, 90.0% or higher, 90.5% or higher, 91.0% or higher, or 92.5% or higher. A diffuse reflectance within these ranges for 800 nm indicates a reduction in defects in the phosphor's crystalline structure or the occurrence of heterogeneous phases in non-luminescent components, which helps to further improve the internal and external quantum efficiency of the α-silicon phosphor. The diffuse reflectance of Ce-activated α-silicon phosphors for light at a wavelength of 800 nm can, for example, be 100.0% or lower, 98.0% or lower, or 95.0% or lower.

[0057] In this specification, diffuse reflectance refers to the value determined by the diffuse reflectance spectrum of a Ce-activated α-Syron phosphor measured using a spectrophotometer. Specifically, diffuse reflectance can be obtained according to the methods described in the examples of this specification. Furthermore, a spectrophotometer such as the "V-550" (product name) manufactured by Nippon Spectrophotometer Co., Ltd. can be used.

[0058] The absorption rate of Ce-activated α-silicon phosphor at a wavelength of 405 nm can be above 65.0%, above 70.0%, above 72.0%, or above 75.0%. The absorption rate of Ce-activated α-silicon phosphor at a wavelength of 405 nm can be below 100.0%, below 90.0%, or below 80.0%.

[0059] From the perspective of further improving internal quantum efficiency, the absorption rate of Ce-activated α-silicon phosphor at a wavelength of 600 nm can be above 0.0%, above 2.0%, above 5.0%, above 7.0%, above 9.0%, or above 9.5%. The absorption rate of Ce-activated α-silicon phosphor at a wavelength of 600 nm can also be below 20.0%, below 18.0%, below 15.0%, or below 12.0%.

[0060] From the perspective of improving external quantum efficiency, the absorption rate of Ce-activated α-Syrone phosphor at a wavelength of 700 nm can be above 3.0%, above 5.0%, above 7.0%, or above 8.0%. The absorption rate of Ce-activated α-Syrone phosphor at a wavelength of 700 nm can also be below 15.0%, below 13.0%, below 10.0%, or below 9.0%.

[0061] The absorptivity of light at a specific wavelength refers to the absorptivity obtained as described below. First, a phosphor is mounted at the opening of an integrating sphere, and light of a specific wavelength is introduced into the integrating sphere as excitation light. The emission spectrum is measured using a spectrophotometer. The number of excitation-reflected photons (Qref) and the number of fluorescence photons (Qem) are calculated from the obtained emission spectrum data. Alternatively, the spectrum of the excitation light is measured in the same manner as above, except that a standard reflector is mounted at the opening of the integrating sphere instead of the phosphor. The number of excitation photons (Qex) is calculated from the obtained spectrum data. Then, the absorptivity of light at the specific wavelength is calculated according to the following formula.

[0062] Absorption rate of light at a specific wavelength = ((Qex - Qref) / Qex) × 100

[0063] The absorption rate of light at a specific wavelength can be obtained, specifically, according to the method described in the embodiments of this specification. Furthermore, a spectrophotometer such as the "MCPD-7000" (trade name) manufactured by Otsuka Electronics Co., Ltd. can be used.

[0064] The internal quantum efficiency of the Ce-activated α-cylon phosphor disclosed herein, when excited by light at a wavelength of 405 nm, can be set to, for example, 75.0% or more, 76.0% or more, 77.0% or more, 78.0% or more, or 79.0% or more. In this specification, internal quantum efficiency refers to the internal quantum efficiency calculated based on the obtained emission spectrum data when the phosphor is excited using light at a wavelength of 405 nm. Specifically, the internal quantum efficiency can be obtained according to the method described in the embodiments of this specification.

[0065] The Ce-activated α-Sylon phosphor disclosed herein has an absorption rate of 65.0% or higher for light at a wavelength of 405 nm and an internal quantum efficiency of 76.0% or higher. From the point of view for practical application, the absorption rate of light at a wavelength of 405 nm can be 72.0% or higher and the internal quantum efficiency can be 78.0% or higher.

[0066] [Method for manufacturing Ce-activated α-cylon phosphors]

[0067] The Ce-activated α-cylon phosphor described above can be manufactured by, for example, the following general method. One example of a method for manufacturing a Ce-activated α-cylon phosphor includes a step of heating a mixture containing Ce-activated α-cylon and an Eu source at 1200-1500°C to obtain a heat-treated product. Another embodiment of this disclosure is a method for manufacturing a Ce-activated α-cylon phosphor that includes this step.

[0068] <Ce-activated α-sialon (raw sialon)>

[0069] Ce-activated α-cyrone (hereinafter also referred to as "raw material cyrone") contains Ce as the luminescent center element and can emit fluorescence. Raw material cyrone may substantially contain no Eu as the luminescent center element, or it may substantially contain only Ce as the luminescent center element. If raw material cyrone substantially contains no Eu as the luminescent center element, it means that no emission peak originating from Eu is observed in the emission spectrum of raw material cyrone excited with light at a wavelength of 405 nm. Conversely, if raw material cyrone substantially contains only Ce as the luminescent center element, it means that only peaks originating from Ce are observed in the emission spectrum of raw material cyrone excited with light at a wavelength of 405 nm. For example, if even if raw material cyrone contains Eu, no independent emission peak originating from Eu is observed, in this specification, Eu is determined not to be an element included as a luminescent center element.

[0070] The raw material silon may contain M, Ce, Si, Al, O, and N as constituent elements. Here, M is at least one element selected from the group consisting of Li, Ca, Mg, Y, and the lanthanides (excluding La, Ce, and Eu). The contents of M, Ce, Si, Al, O, and N are within the range of the values ​​for each element as stated above, based on the total contents of M, Ce, Si, Al, O, and N in Ce-activated α-silon phosphors. Here, "in Ce-activated α-silon phosphors" can be replaced with "in raw material silon".

[0071] For example, in the raw material silon, based on the total content of M, Ce, Si, Al, O and N in the raw material silon, the content of M can be 1 to 4 mol%, the content of Ce can be 0.05 to 2 mol%, the content of Si can be 25 to 45 mol%, the content of Al can be 4 to 12 mol%, the content of O can be 0.5 to 5 mol%, and the content of N can be 40 to 60 mol%, or the content of M can be 1 to 4 mol%, the content of Ce can be 0.05 to 2 mol%, the content of Si can be 25 to 45 mol%, the content of Al can be 5 to 9 mol%, the content of O can be 0.5 to 5 mol%, and the content of N can be 40 to 60 mol.

[0072] The raw material silon may contain a crystal with the same crystal structure as α-type silon as the main crystal, or it may be formed by a crystal with the same crystal structure as α-type silon. In the powder X-ray diffraction pattern of the raw material silon, the ratio of the maximum diffraction intensity of the heterogeneous phase to the diffraction intensity of the (101) plane may be less than 10%, less than 5%, less than 3%, or less than 2%.

[0073] The raw material silon may contain, for example, α-type silon represented by the following general formula (1).

[0074] (M a+ x Ce 3+ y Si 12-(m+n) Al (m+n) O n N 16-n (1)

[0075] In general formula (1), M is at least one element selected from the group consisting of Li, Ca, Mg, Y and lanthanides (excluding La, Ce and Eu). When the valence of M is set to a, m = ax + 3y, Ce 3+ Replace M with the following condition: 0.3 ≤ x + y ≤ 2, 0.03 ≤ y ≤ 0.5, 0 ≤ n ≤ m.

[0076] The raw material silon may contain Ca, or may contain α-type silon with Ca dissolved in solution. In the above general formula (1), M may be Ca, or may be Ca and two or more elements selected from the group consisting of at least one element of Li, Mg, Y and lanthanides (excluding La, Ce and Eu). When M is Ca, in general formula (1), a=2. The presence of Ca in the raw material silon can be confirmed by quantitative elemental analysis using an ICP-based luminescence spectrophotometer.

[0077] In general formula (1), x + y can be greater than or equal to 0.4, 0.5, 0.6, or 0.7, or less than or equal to 1.8, 1.5, 1.3, 1.1, 1.0, or 0.9. In general formula (1), y can be greater than or equal to 0.05 or 0.06, or less than or equal to 0.4, 0.3, 0.2, or 0.1. In general formula (1), n ​​can be greater than or equal to 0.01, 0.05, or 0.10, or less than m.

[0078] The raw material silon contains α-type silon as represented by the above general formula (1), which means that in the powder X-ray diffraction pattern of the raw material silon, the ratio of the maximum diffraction intensity of the heterogeneous phase to the diffraction intensity of the (101) plane is less than 10%, and the content ratio of each constituent element (M, Ce, Si, Al, O and N) calculated by using a multi-element type ICP emission spectrophotometer and based on the analysis of the ICP emission spectrophotometer method and the analysis of the oxygen and nitrogen content using an oxygen and nitrogen analyzer is equal to the ratio shown in general formula (1).

[0079] The raw material silon can be represented, for example, by the general formula (1) above. In this case, M, x+y, y, and n are as described above. The constituent elements and proportions of the raw material silon can be determined by analyzing the oxygen and nitrogen content using an oxygen and nitrogen analyzer and by analyzing using a multi-element ICP luminescence spectrophotometer and according to the ICP luminescence spectrophotometric method. The raw material silon being represented by the general formula (1) above means that when the constituent elements and proportions of the raw material silon are determined by the above analysis, the content ratios of Ce, Si, Al, O, N, and M in the general formula (1) are within the range shown in the general formula (1), and the content of elements other than the above elements is less than 1.5% by mass.

[0080] One embodiment of the manufacturing method may include a step of obtaining raw material silron (hereinafter also referred to as "the step of obtaining α-silron"). In the step of obtaining α-silron, for example, the raw material silron is obtained by calcining a raw material composition containing a Si source, an Al source, and a Ce source.

[0081] Si source refers to a compound or monomer with silicon as its constituent element, Al source refers to a compound or monomer with aluminum as its constituent element, and Ce source refers to a compound or monomer with cerium as its constituent element. In this specification, compounds with silicon as their constituent element are also referred to as silicon compounds, compounds with aluminum as their constituent element are referred to as aluminum compounds, and compounds with cerium as their constituent element are referred to as cerium compounds. Silicon compounds, aluminum compounds, and cerium compounds can each be any one of nitrides, oxides, oxynitrides, and hydroxides. At least one of the Si source, Al source, and Ce source can be a nitride. This nitride source, because it contains nitrogen, a constituent element of silane, can also be considered a nitrogen source.

[0082] Examples of silicon compounds include silicon nitride (Si3N4) and silicon dioxide (SiO2).

[0083] Examples of aluminum compounds include aluminum nitride (AlN), aluminum oxide (Al2O3), and aluminum hydroxide (Al(OH)3).

[0084] Examples of cerium compounds include cerium oxide (CeO2), cerium nitride (CeN), cerium hydroxide (Ce(OH)4), and cerium fluoride (CeF3).

[0085] The raw material composition may contain other raw materials, including elements other than Si, Al, and Ce sources, that can form α-type silanes. Examples of other raw materials include Li sources and Ca sources. Li source refers to a compound or monomer with lithium as a constituent element, and Ca source refers to a compound or monomer with calcium as a constituent element. In this specification, compounds with lithium as a constituent element are also referred to as lithium compounds, and compounds with calcium as a constituent element are referred to as calcium compounds. Lithium compounds and calcium compounds can be any of halides, nitrides, oxides, oxynitrides, carbonates, and hydroxides, respectively. Examples of lithium compounds include lithium halides, lithium nitrides, lithium oxides, lithium carbonates, and lithium hydroxides, such as lithium fluoride. Examples of calcium compounds include calcium halides, calcium oxides, calcium carbonates, calcium nitrides, and calcium hydroxides, such as calcium fluoride.

[0086] The feedstock composition may further contain α-cyrone or Ce-activated α-cyrone. α-cyrone or Ce-activated α-cyrone may serve as the framework or core for obtaining the feedstock cyrone.

[0087] The raw material composition can be prepared, for example, by weighing and mixing the compounds. The mixing ratio of each compound can be designed according to the composition of the raw material silane, the Ce-activated α-silane phosphor, and the α-type silane contained therein. Mixing can be performed using either dry mixing or wet mixing methods. Dry mixing, also known as dry blending, can be a method of mixing the components using a V-type mixer or similar equipment. Wet mixing can be a method of mixing the components by adding a solvent or dispersion medium such as water to prepare a solution or slurry, then removing the solvent or dispersion medium. Furthermore, after weighing and mixing the compounds, the particle size can be adjusted for use as a raw material composition. Particle size adjustment can be performed, for example, by sieving.

[0088] From the viewpoint of promoting the grain growth of the main crystalline phase of α-silicon while ensuring sufficient Ce solid solution, the firing temperature of the raw material composition can be 1600°C or higher, 1650°C or higher, or 1700°C or higher. Conversely, from the viewpoint of sufficiently suppressing the decomposition of the main crystalline phase of α-silicon, the firing temperature of the raw material composition can be 2000°C or lower, 1900°C or lower, or 1800°C or lower. The firing temperature of the raw material composition can, for example, be 1600–2000°C, 1650–1900°C, or 1700–1800°C.

[0089] From the perspective of promoting the primary particle growth of α-sialon, the firing time of the raw material composition can be more than 1 hour, more than 3 hours, or more than 5 hours. Furthermore, from an economic point of view, the firing time of the raw material composition can be less than 30 hours, less than 28 hours, or less than 25 hours.

[0090] Firing can be performed, for example, under a nitrogen atmosphere. The nitrogen atmosphere can be atmospheric pressure; however, by heating under high nitrogen pressure, the decomposition of the generated α-silicon at high temperatures can be suppressed. Alternatively, firing can be performed, for example, under a pressurized atmosphere. When the atmosphere is set to pressurized, the pressure can be 0.001 MPaG or higher, 0.005 MPaG or higher, 0.01 MPaG or higher, or 0.02 MPaG or higher. Alternatively, the pressure can be 100 MPaG or lower, 50 MPaG or lower, 10 MPaG or lower, 5 MPaG or lower, or 1 MPaG or lower.

[0091] In the process of obtaining α-sialon, the number of firings can be one or more times. The number of firings can be, for example, five or fewer times. When the number of firings is two or more times, the firing conditions can be the same or different for each firing.

[0092] The silon used as a raw material for heat treatment can be the calcined product obtained by the above method directly, or it can be used after adjusting the particle size. The particle size can be adjusted by, for example, crushing (coarse grinding) using a crusher, grinding using a jet mill, or sieving using a vibrating screen.

[0093] <Heat Treatment Process>

[0094] One embodiment of the manufacturing method involves a step of heating (annealing) a mixture containing silron and an Eu source at 1200-1500°C to obtain a heat-treated product (hereinafter also referred to as the "heat treatment step"). The inventors have discovered that by performing such a heat treatment step, Ce-activated α-silron phosphors with excellent internal quantum efficiency can be manufactured. The heating temperature of 1200-1500°C is lower than the firing temperature generally used to obtain silron from the aforementioned raw material composition. It is believed that heating at this temperature can suppress further growth of silron grains and reduce the density of crystal defects in the heat-treated product, thereby increasing the diffuse reflectance of light at the emission peak wavelength in the emission spectrum when the silron phosphor is excited by light at a wavelength of 405 nm, and further improving the internal quantum efficiency.

[0095] In particular, in the aforementioned heat treatment process, heating the raw material silon together with the Eu source can improve the internal quantum efficiency. Generally, it is known that in α-silon phosphors, the use of Ce as the luminescent center element and the use of Eu produce fluorescence in different wavelength ranges. Furthermore, in Ce-activated α-silon phosphors, combining Ce with other fluorescent elements such as Eu is not considered ideal for obtaining excellent luminescence properties; therefore, in the preparation of Ce-centered α-silon phosphors, the addition of other elements such as Eu that could potentially become luminescent centers is avoided. However, in the aforementioned heat treatment process, heating the raw material silon together with the Eu source, while the reason is uncertain, is believed to be due to the reduced density of crystal defects, leading to more efficient processing and thus improving the internal quantum efficiency.

[0096] A mixture containing the raw material silon and the Eu source, for example, can be prepared by adding the Eu source to the raw material silon and mixing.

[0097] Eu source refers to a compound or monomer containing europium as a constituent element. In this specification, compounds containing europium as a constituent element are also referred to as europium compounds. Examples of europium compounds include europium oxides (europium oxide), europium hydroxides (europium hydroxide), europium nitrides (europium nitride), europium sulfides (europium sulfide), and europium halides (europium halide). Examples of europium halides include europium fluoride, europium chloride, europium bromide, and europium iodide. In these compounds, europium can be trivalent or divalent. A europium compound may be, for example, selected from one or more compounds formed by europium oxides, nitrides, and halides. A europium compound preferably contains europium oxide.

[0098] The content of the Eu source in the above mixture, relative to 100 parts by mass of the raw material silon in the mixture, can be 0.01 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, or 0.3 parts by mass or more. By setting the content of the Eu source within the above-mentioned range, the internal quantum efficiency of the Ce-activated α-silon phosphor can be further improved. Furthermore, the content of the Eu source in the above mixture, relative to 100 parts by mass of the raw material silon in the mixture, can be 10.0 parts by mass or less, 8.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, or 2.0 parts by mass or less. By setting the content of the Eu source within the above-mentioned range, the amount of heterogeneous phases that adversely affect the luminescence properties of the Ce-activated α-silon phosphor can be reduced. The content of the Eu source in the mixture, relative to 100 parts by mass of the raw material silon in the mixture, can, for example, be 0.01 to 10 parts by mass, 0.05 to 5.0 parts by mass, or 0.1 to 3.0 parts by mass.

[0099] The heating temperature in the heat treatment process is 1200~1500℃, and can be above 1250℃ or above 1280℃. By setting the heating temperature within the above range, the internal quantum efficiency of the Ce-activated α-cylon phosphor can be further improved. Alternatively, the heating temperature can be below 1450℃, below 1400℃, or below 1360℃. By setting the heating temperature within the above range, the internal quantum efficiency of the Ce-activated α-cylon phosphor can be further improved. The heating temperature in the heat treatment process can, for example, be 1250~1450℃ or 1250~1400℃.

[0100] In the heat treatment process, the heat treatment can be carried out in an atmosphere containing at least one gas selected from the group consisting of rare gases and reducing gases. Examples of rare gases include argon and helium. Argon can be a rare gas. Examples of reducing gases include hydrogen, ammonia, hydrocarbon gases, and carbon monoxide. Hydrogen can be a reducing gas. The content of at least one gas selected from the group consisting of rare gases and reducing gases in the atmosphere, based on the total volume of the atmosphere, can be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more. In addition, the content of argon, based on the total volume of the atmosphere, can be 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0101] The heat treatment can be carried out under atmospheric pressure or under a pressurized atmosphere. In the case of a pressurized atmosphere, the pressure can be, for example, below 0.05 MPaG or below 0.01 MPaG. The pressure can be the same as or less than the firing pressure during the process of obtaining the α-silicon described above.

[0102] From the perspective of further improving internal quantum efficiency, the heating time in the heat treatment can be more than 2 hours, more than 4 hours, or more than 6 hours. However, from an economic point of view, the heating time can be less than 24 hours, less than 20 hours, or less than 12 hours. For example, the heating time can be 6 to 12 hours.

[0103] In the heat treatment process, the number of heat treatments can be one or more times. The number of heat treatments can be, for example, five or fewer times, or four or fewer times. When the number of heat treatments is two or more times, the type and content of the Eu source, the heating temperature, the heating atmosphere, and the heating time for each treatment can be the same or different, and can be appropriately set within the above range. However, the heating temperature must be in the range of at least 1200~1500°C.

[0104] One embodiment of the manufacturing method may also include other steps besides the steps for obtaining α-silicon and the heat treatment step described above. Examples of other steps include a step of treating the heat-treated product obtained by the above heat treatment with acid (acid treatment step) and a step of classifying the heat-treated product or the acid-treated product (classification step).

[0105] <Acid Treatment Process>

[0106] Acid treatment can be performed by contacting the heat-treated material with an acid. Specifically, for example, this can be done by adding the heat-treated material to an acid and stirring. By performing acid treatment, the amount of altered phases or residual compounds or heterogeneous phases from the Eu source formed due to heat treatment can be reduced, thus further improving the internal quantum efficiency of Ce-activated α-Sylon phosphors. An acid-treated material is obtained in the acid treatment process.

[0107] Examples of acids used in acid treatment include hydrofluoric acid (fluoric acid), nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof (mixed acids). For example, a mixed acid of hydrofluoric acid and nitric acid can be used. In a mixed acid of hydrofluoric acid and nitric acid, the mass ratio of HF content to HNO3 content can be, for example, 0.5 / 1 to 1 / 1.

[0108] The acid treatment time can be, for example, 10 minutes or more, and less than 1 hour. Furthermore, the acid treatment time refers to the contact time between the heated material and the acid. Additionally, the acid treatment can be performed at room temperature or under heating. The acid treatment temperature can be, for example, 30°C or higher, 50°C or higher, or 70°C or higher. The acid treatment temperature can be 100°C or lower, or 90°C or lower. Furthermore, the acid treatment temperature refers to the temperature of the acid used in the acid treatment.

[0109] The acid treatment can be performed once or more than twice. For example, the number of acid treatments can be five or less, or four or less. When the number of acid treatments is two or more, the treatment time, temperature, and type of acid for each treatment can be the same or different, and can be appropriately set within the above range. When performing two acid treatments, for example, acid treatment with a mixture of hydrofluoric acid and nitric acid can be followed by acid treatment with hydrochloric acid. According to this treatment, undissolved Eu in the heat-treated material can be converted to EuF3 using the mixed acid, and then the EuF3 can be dissolved in hydrochloric acid to remove it.

[0110] <Graded Processes>

[0111] Grading can be either wet or dry. As an example of wet grading, water slurry grading can be cited. In water slurry grading, for example, small particles are removed by adding heat-treated or acid-treated material to a mixed solvent containing ion-exchanged water and a dispersant (e.g., sodium hexametaphosphate) or a mixed solvent containing ion-exchanged water and ammonia, stirring, and then allowing it to stand.

[0112] The α-silicon phosphor obtained by the above manufacturing method exhibits excellent internal quantum efficiency. The above manufacturing method can also be understood as a method for improving the internal quantum efficiency of α-silicon phosphors. For example, the method for improving the internal quantum efficiency of a phosphor involves heating a mixture containing Ce-activated α-silicon and an Eu source at 1200-1500°C to obtain a heat-treated product. Various embodiments of the above manufacturing method can be applied without particular limitation as specific embodiments of this method.

[0113] The Ce-activated α-silicon phosphors described above can be used alone or in combination with other phosphors. Due to their excellent internal quantum efficiency, Ce-activated α-silicon phosphors are suitable for use in light-emitting devices such as LEDs. Ce-activated α-silicon phosphors can also be used, for example, dispersed in a curing resin. The curing resin can be, for example, a resin suitable for use as a sealing resin in light-emitting devices.

[0114] The above description describes several embodiments; however, this disclosure is not limited to any of the above embodiments. Furthermore, the descriptions of the above embodiments are interchangeable.

[0115] [Example]

[0116] The present disclosure is further described in detail below with reference to the embodiments and comparative examples. However, the present disclosure is not limited to the following embodiments.

[0117] [Making of raw material silon]

[0118] <Production of raw material Cyron A>

[0119] Set the design components as Ca 0.645 Ce 0.07 Si 9.75 Al 2.25 O 0.75 N 15.25A raw material powder a was prepared, comprising a formulation of 52.3 mol% silicon nitride powder (manufactured by UBE Co., Ltd., E10 grade), 36.2 mol% aluminum nitride powder (manufactured by Tokuyama Co., Ltd., E grade), 1.1 mol% cerium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd., C type), 2.6 mol% calcium fluoride powder (manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd., premium grade reagent), and 7.8 mol% calcium carbonate powder (manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd., premium grade reagent). In this raw material powder a, the content of calcium fluoride powder (CaF2 / (CaF2+CaCO3)) based on the total amount of calcium compounds was 25 mol%. Furthermore, calcium fluoride and calcium carbonate were converted to calcium oxide with the same molar amount of calcium, and the formulation composition was calculated in a manner that satisfies the above-described design composition. The raw material powder a was mixed in a bag for several minutes, and then the resulting mixture was passed entirely through a nylon sieve (pore size: 150 μm) to obtain the raw material composition.

[0120] 35g of the above-mentioned raw material composition was filled into a boron nitride crucible with an inner diameter of 60mm and a height of 30mm, and calcined in an electric furnace equipped with a carbon heater under a nitrogen atmosphere of 0.03MPaG. The calcination temperature was 1750°C, and the calcination time was 8 hours. The calcined material was then broken down using a pulverizer (NITS-143PL high-speed pulverizer manufactured by NITS-143PL Co., Ltd.) to allow all the calcined material to pass through a sieve (pore size: 250μm) to obtain the raw material silon A (the phosphor of Comparative Example 1).

[0121] <Production of raw material Cyron B>

[0122] Except for setting the doping amount of calcium fluoride powder to 5.2 mol% and the doping amount of calcium carbonate powder to 5.2 mol% (CaF2 / (CaF2+CaCO3)=50 mol%), the other preparations were carried out in the same manner as described above for the preparation of raw material silon A, thus obtaining the raw material composition. 300 g of this raw material composition was filled into a boron nitride crucible with an inner diameter of 150 mm and a height of 55 mm, and calcined at 1750 °C for 16 hours in an electric furnace equipped with a carbon heater under a nitrogen atmosphere of 0.03 MPaG to obtain a calcined product. The obtained calcined product was coarsely pulverized using a pulverizer, then further pulverized using a jet mill (manufactured by Pneumatic Industries, Ltd., Japan, PJM-80, sample feed rate: 50 g / min, pulverizing pressure: 0.2 MPa), and then sieved using a vibrating sieve (aperture size: 45 μm). The powder passing through the vibrating sieve was recovered as raw material silon B (the phosphor of Comparative Example 3).

[0123] <Preparation of raw material Citron C>

[0124] Except for replacing the calcium carbonate powder with calcium oxide (the object after decarbonating the calcium carbonate powder by treating it in the atmosphere at 1000°C for 8 hours), the other procedures were carried out in the same manner as described above in the "Preparation of Raw Material Siron B" section, and a raw material composition was obtained. 200g of this raw material composition was filled into a boron nitride crucible with an inner diameter of 100mm and a height of 85mm, and calcined in an electric furnace equipped with a carbon heater at 1750°C for 24 hours under a nitrogen atmosphere of 0.03MPaG to obtain a calcined product. The obtained calcined product was subjected to coarse grinding, pulverization, and sieving in the same manner as described above in the "Preparation of Raw Material Siron B" section, to obtain raw material Siron C (the phosphor of Comparative Example 7).

[0125] <Making of Raw Material Cylon D>

[0126] Except for replacing calcium carbonate powder with calcium oxide, the preparation of the raw material silon B was carried out in the same manner as described above, and the raw material product was obtained. 300g of this raw material composition was filled into a boron nitride crucible with an inner diameter of 150mm and a height of 55mm, and calcined at 1750°C for 16 hours in an electric furnace equipped with a carbon heater under a nitrogen atmosphere of 0.03MPaG to obtain a calcined product. The calcined product was then subjected to coarse grinding, pulverization, and sieving in the same manner as described above for the preparation of raw material silon B, to obtain raw material silon D (the phosphor of Comparative Example 8).

[0127] <Making of raw material Cyron E>

[0128] Except for the raw material powder obtained by adding europium oxide powder (manufactured by Shin-Etsu Chemical Industry Co., Ltd., RU grade) at an external percentage of 0.5% by mass to the raw material powder used in the above-mentioned <Preparation of Raw Material Siron D>, all other procedures were carried out in the same manner as in the above-mentioned <Preparation of Raw Material Siron D> to obtain raw material Siron E (the phosphor of Comparative Example 12).

[0129] [Processing of raw material silon]

[0130] For the raw materials silon A to E, as shown in Tables 1 to 2, one or more of the following treatments—heat treatment, acid treatment, and water sifting treatment—were performed to obtain the phosphors of Comparative Examples 2, 4 to 6, 9 to 11, and Examples 1 to 8. Furthermore, the phosphors of Examples 1 to 8 contain α-type silon as shown in the following general formula (1-1).

[0131] (Ca 2+ x Ce 3+ y Si 12-(m+n) Al (m+n) O n N 16-n (1-1)

[0132] In general formula (1-1), m = 2x + 3y, Ce 3+ Replace Ca in the following conditions: 0.7 ≤ x + y ≤ 0.9, 0.03 ≤ y ≤ 0.08, 0 ≤ n ≤ m / 2.

[0133] <Heat Treatment>

[0134] Regarding Comparative Examples 4-6 and 9-10, the α-silicon (raw material silicon) shown in Tables 1-2 was heated in an electric furnace equipped with a carbon heater at the temperatures listed in Tables 1-2 under an argon atmosphere of 0.03 MPaG. The heating time was set to 8 hours. Regarding Examples 1-8, europium oxide powder (manufactured by Shin-Etsu Chemical Industry Co., Ltd., RU grade) in the amounts shown in Tables 1-2 was added to the α-silicon shown in Tables 1-2 as an Eu source, and the resulting mixture was heated in the same manner as described above. The amount of Eu source listed in Tables 1-2 refers to the amount based on the total mass of each α-silicon. In addition, regarding Comparative Example 11, cerium oxide powder (manufactured by Shin-Etsu Chemical Industry Co., Ltd., Type C) instead of europium oxide powder was added to raw material silicon D, and the mixture obtained by adding 1% by mass based on the total mass of raw material silicon D was heated in the same manner as described above.

[0135] <Acid Treatment>

[0136] In cases with heat treatment, the heat-treated product obtained through heat treatment is added. In cases without heat treatment, α-sialon (as shown in Tables 1-2) is added to a mixture of hydrofluoric acid and nitric acid heated to 80°C (48% by mass hydrofluoric acid: 60% by mass nitric acid: water = 1:1:6 (volume ratio)), and stirred for 30 minutes. Then, the mixture is filtered, washed with water, and dried to recover the acid-treated product.

[0137] <Grading (Water Sifting) Treatment>

[0138] In Examples 2 and 6, sedimentation fractionation was used to remove the fine powder contained in the acid-treated product. More specifically, first, water containing a small amount of dispersant was prepared in a beaker. The acid-treated product was dispersed in the water, and after standing for a specified time, the supernatant from the water surface to a specified height was removed using a pump. Then, a specified amount of water containing a small amount of the above-mentioned dispersant was added to the beaker, and the dispersion, standing, and supernatant removal were repeated to remove the fine powder. The specified time and specified height were adjusted according to Stokes' law, so that fine powder with a particle size less than 7.5 μm was removed in Example 2, and fine powder with a particle size less than 5 μm was removed in Example 6.

[0139] [evaluate]

[0140] <diffuse reflectance>

[0141] The diffuse reflectance of the phosphors in the comparative examples and embodiments was measured using an integrating sphere apparatus (trade name: ISV-469) mounted on a UV-Vis spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd., trade name: V-550). After baseline correction using the standard reflector attached to the apparatus, a solid sample holder filled with the phosphor of the test object was mounted onto the spectrophotometer, and the diffuse reflectance was measured in the wavelength range of 220–850 nm. The peak wavelength of the emission spectrum of each phosphor and the diffuse reflectance values ​​at 600 nm, 700 nm, and 800 nm were recorded in the measurement results. The results are shown in Tables 1 and 2.

[0142] <Excitation light absorption rate, fluorescence properties, and chromaticity x and chromaticity y>

[0143] For the phosphors of each comparative example and embodiment, the excitation light absorptivity, emission peak wavelength, emission peak half-width, emission intensity ratio, internal quantum efficiency, and external quantum efficiency were calculated according to the following procedure when the excitation wavelength was set to 405 nm. The results are shown in Tables 1-2.

[0144] First, the phosphor of the test object was filled into the concave sample groove and the surface was smoothed, and then mounted into the opening of the integrating sphere. Monochromatic light with a wavelength of 405 nm, dispersed by the Xe lamp, was guided into the integrating sphere using an optical fiber as the excitation light for the phosphor. This monochromatic excitation light was then irradiated onto the phosphor of the test object, and the emission spectrum was measured. A spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., trade name: MCPD-7000) was used for the measurement. The emission spectra of the phosphors of Comparative Examples 7 and 12 and Examples 1 and 2 obtained above are shown below. Figure 1 .

[0145] The emission peak wavelength and half-width at half-maximum (WHM) were determined from the obtained emission spectrum data. Additionally, the fluorescence intensity at the emission peak wavelength (emission peak intensity) and the fluorescence intensity at 580 nm were determined from the obtained emission spectrum data, and the ratio of the emission intensities was calculated using the following formula. The emission intensity observed at 580 nm was used as an indicator of the emission from Eu.

[0146] The ratio of luminous intensity = {(luminous intensity at 580nm) / (intensity of luminous peak)} × 100

[0147] Furthermore, the number of excitation-reflected photons (Qref) and the number of fluorescence photons (Qem) were calculated from the obtained emission spectrum data. The number of excitation-reflected photons was calculated over the same wavelength range as the number of excitation photons, while the number of fluorescence photons was calculated over the range of 415–800 nm. Additionally, using the same apparatus, a standard reflective plate (manufactured by Labsphere, Spectralon (registered trademark)) with a reflectivity of 99% was installed at the opening of the integrating sphere, and the spectrum of excitation light at a wavelength of 405 nm was measured. At this time, the number of excitation photons (Qex) was calculated from the spectrum over the wavelength range of 400–415 nm.

[0148] Based on the above calculation results, the excitation light absorption rate, internal quantum efficiency, and external quantum efficiency of the phosphor at 405 nm of the tested object are obtained according to the calculation formula shown below.

[0149] Absorption rate of excitation light at 405 nm = ((Qex - Qref) / Qex) × 100

[0150] Internal quantum efficiency = (Qem / (Qex-Qref)) × 100

[0151] External quantum efficiency = (Qem / Qex) × 100

[0152] Furthermore, based on the above formula, the relationship between the external quantum efficiency and the absorption rate of the 405nm excitation light and the internal quantum efficiency can be expressed as follows.

[0153] External quantum efficiency = Absorption rate of excitation light at 405 nm × Internal quantum efficiency

[0154] In addition, based on the spectral data of the obtained emission spectrum in the wavelength range of 415~800nm, according to JIS Z8724:2015 "Methods for measuring color - Color of light source", the x-value (chromaticity x) and y-value (chromaticity y) of the CIE chromaticity coordinates in the XYZ color system specified in JIS Z 8781-3:2016 "Color measurement - Part 3: CIE tristimulus values" are calculated, thereby obtaining chromaticity x and chromaticity y.

[0155] In addition, for a standard sample of Eu-activated β-sialon phosphor (manufactured by Sialon Co., Ltd., Standard Phosphor Gree, Lot No. NSG1301, the absorption rate, internal quantum efficiency, and external quantum efficiency of the excitation light at 405 nm measured by the method according to ISO24936 are 81%, 81%, and 65% respectively), according to the above measurement method, the absorption rate, internal quantum efficiency, external quantum efficiency of the excitation light at 405 nm, and chromaticity x and chromaticity y were measured. As a result, the absorption rate of the excitation light at 405 nm was 83.5%, the internal quantum efficiency was 83.0%, the external quantum efficiency was 69.3%, the chromaticity x was 0.347, and the chromaticity y was 0.628.

[0156] Regarding the measured values of the absorption rate of the excitation light, fluorescence characteristics, and chromaticity x and chromaticity y, there are cases where the values change when the manufacturer of the measuring device, manufacturing batch number, etc. are changed. Therefore, as the various measured values, the values measured by the measurement method described in this specification are adopted. However, in the case of changing the manufacturer of the measuring device, manufacturing batch number, etc., the measured values can be corrected based on the measured values obtained from the above standard sample.

[0157] <Absorption rate of light at 600 nm and 700 nm>

[0158] In addition to using monochromatic light with wavelengths of 600 nm or 700 nm separated from the Xe lamp to replace the monochromatic light with a wavelength of 405 nm separated from the Xe lamp when measuring the emission spectrum, and measuring the spectrum of the excitation light with wavelengths of 600 nm or 700 nm to replace the spectrum of the excitation light with a wavelength of 405 nm, the absorption rate of light at 600 nm and 700 nm was measured in the same way as the above absorption rate of the excitation light. The results are shown in Tables Ⅰ~Ⅱ.

[0159]

[0160]

[0161] <Content of Eu>

[0162] The Eu content was determined for the phosphors of Examples 3-6, 8, and Comparative Example 12. The Eu content was determined using an ICP-based spectrophotometer. A quantification of 0.1% or more was performed using an alkaline fusion method, and a quantification of less than 0.1% was performed using a pressurized acid decomposition method to dissolve the phosphor and prepare a sample solution. The obtained sample solution was used for quantitative analysis of europium using an ICP-based spectrophotometer (manufactured by Agilent Technologies, trade name: 5110VDV). The Eu content was calculated from the results. Furthermore, for Examples 3-8 and Comparative Example 12, the phosphors were treated with 18% by mass hydrochloric acid heated to 80°C for 30 minutes (hydrochloric acid washing). For Examples 3-6, 8, and Comparative Example 12, the Eu content was further measured after hydrochloric acid washing. The results are shown in Table 3. Furthermore, the Eu content listed in Table 3 refers to the mass percentage based on the total mass of each phosphor. In addition, regarding Examples 3, 4, 6-8 and Comparative Example 12, the excitation light absorption rate, fluorescence characteristics, chromaticity, and absorption rates of light at 600 nm and 700 nm after hydrochloric acid cleaning, as well as the changes in these values ​​from the values ​​before hydrochloric acid cleaning (values ​​after hydrochloric acid cleaning - values ​​before hydrochloric acid cleaning) are shown in Table 4.

[0163]

[0164]

[0165] Regarding the phosphors of Examples 3-5, 6, and 8, the Eu content changed significantly before and after hydrochloric acid washing. On the other hand, regarding the phosphor of Comparative Example 12, no significant change in Eu content was observed before and after hydrochloric acid washing. Regarding Comparative Example 12, it is believed that because an Eu source was added during the preparation of Ce-activated α-cyrone, Eu entered the α-cyrone crystals within the Ce-activated α-cyrone phosphor. However, regarding the phosphors of Examples 3-5, 6, and 8, Eu did not enter the α-cyrone crystals.

Claims

1. A Ce-activated α-silicon phosphor, which exhibits an emission peak in the wavelength range of 470–525 nm in its emission spectrum when excited by light at a wavelength of 405 nm. The diffuse reflectance of light at the wavelength of the emission peak is above 86.5%.

2. The Ce-activated α-cerone phosphor as described in claim 1, wherein it contains Eu.

3. The Ce-activated α-cerone phosphor as described in claim 2, wherein, The Eu content, based on the total mass of the Ce-activated α-cylon phosphor, is 0.0001 to 1.5% by mass.

4. The Ce-activated α-cerone phosphor according to any one of claims 1 to 3, wherein, The half-width of the emission peak is greater than 100 nm.

5. The Ce-activated α-cerone phosphor according to any one of claims 1 to 3, wherein, In the emission spectrum, the ratio of the emission intensity observed at a wavelength of 580 nm to the intensity of the emission peak is less than 45%.

6. The Ce-activated α-cerone phosphor according to any one of claims 1 to 3, wherein, The Ce-activated α-cylon phosphor contains M, Ce, Si, Al, O, and N as constituent elements. M is at least one element selected from the group consisting of Li, Ca, Mg, Y, and the lanthanides excluding La, Ce, and Eu. The total content of M, Ce, Si, Al, O, and N in the Ce-activated α-silicon phosphor is used as a basis. The content of M is 1-4 mol%. The Ce content is 0.05~2 mol%. The Si content is 25-45 mol%. The Al content is 4-12 mol%. The content of O is 0.5-5 mol%. The content of N is 40-60 mol.

7. The Ce-activated α-cerone phosphor according to any one of claims 1 to 3, wherein, The Ce-activated α-cylon phosphor contains the α-type cylon represented by the following general formula (1). (M a+ x ,What 3+ y )And 12-(m+n) the (m+n) A n N 16-n (1) In general formula (1), M is at least one element selected from the group consisting of Li, Ca, Mg, Y, and lanthanides excluding La, Ce, and Eu. When the valence of M is set to a, m = ax + 3y, Ce 3+ Replace M with 0.3≤x+y≤2, 0.03≤y≤0.5, 0≤n≤m.

8. A method for manufacturing a Ce-activated α-cylon phosphor, comprising: heating a mixture containing Ce-activated α-cylon and an Eu source at 1200-1500°C to obtain a heat-treated product.

9. The manufacturing method as described in claim 8, wherein, The content of the Eu source in the mixture is 0.1 to 3.0 parts by mass per 100 parts by mass relative to the content of Ce-activated α-cyrone.

10. The manufacturing method as described in claim 8 or 9, wherein, The heat treatment is carried out in an atmosphere containing at least one of the group consisting of rare gases and reducing gases.

11. The manufacturing method as claimed in claim 8 or 9, further comprising a step of acid treatment of the heat-treated material.

12. The manufacturing method as described in claim 8 or 9, further comprising a step of obtaining the Ce-activated α-cylon by calcining a raw material composition containing a Si source, an Al source and a Ce source.

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