Nitride phosphors and light-emitting devices

Abstract

The present invention provides a nitride phosphor that can obtain a higher luminous flux when used in a light-emitting device. [Solution] A nitride phosphor whose composition includes at least one group 2 element selected from the group consisting of Mg, Ca, Sr, and Ba, Eu, Si, Al, and N, wherein the ratio of the total molar content of the group 2 elements and Eu to the molar content of Al in the composition is 0.8 or more and 1.1 or less, the ratio of the molar content of Eu is 0.002 or more and 0.08 or less, the ratio of the molar content of Si is 0.8 or more and 1.2 or less, and the ratio of the total molar content of Si and Al is 1.8 or more and 2.2 or less. The nitride phosphor has an average aspect ratio, which is the ratio of the minor axis to the major axis, of 0.72 or more and an average circularity of 0.82 or more and 0.92 or less.

Description

[Technical Field]

[0001] This disclosure relates to nitride phosphors and light-emitting devices. [Background technology]

[0002] Light-emitting devices combining light-emitting diodes (LEDs) and phosphors are used in lighting devices, backlights for liquid crystal displays, and the like. Examples of phosphors used in light-emitting devices include nitride phosphors containing nitrogen in their composition, such as those using CaAlSiN3 as the base crystal. 2+ Red phosphors activated by (CASN) (hereinafter also referred to as "CASN phosphors") and (Sr,Ca)AlSiN3:Eu (hereinafter also referred to as "SCASN phosphors") in which some of the Ca in CASN phosphors is replaced with Sr are known. CASN phosphors and SCASN phosphors have emission peak wavelengths in a wide range from 600 nm to 670 nm, depending on their composition.

[0003] In relation to nitride phosphors, Patent Document 1 describes a phosphor powder in which the average circularity and the standard deviation of circularity are within a predetermined range. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2023 / 037727 [Overview of the project] [Problems that the invention aims to solve]

[0005] One aspect of this disclosure aims to provide a nitride phosphor that can obtain a higher luminous flux when used in a light-emitting device, and a light-emitting device containing the same. [Means for solving the problem]

[0006] The first embodiment is a nitride phosphor whose composition includes at least one group 2 element selected from the group consisting of Mg, Ca, Sr, and Ba, as well as Eu, Si, Al, and N. The nitride phosphor has a ratio of the total molar content of group 2 elements and Eu to the molar content of Al in its composition of 0.8 to 1.1, a ratio of the molar content of Eu of 0.002 to 0.08, a ratio of the molar content of Si of 0.8 to 1.2, and a ratio of the total molar content of Si to Al of 1.8 to 2.2. The nitride phosphor also has an average aspect ratio, which is the ratio of the minor axis to the major axis, of 0.72 to 0.77, and an average circularity of 0.82 to 0.92.

[0007] The second embodiment is a light-emitting device comprising a fluorescent member containing a nitride phosphor of the first embodiment and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm. [Effects of the Invention]

[0008] According to one aspect of this disclosure, it is possible to provide a nitride phosphor that can obtain a higher luminous flux when used in a light-emitting device, and a light-emitting device containing the same. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a scanning electron microscope (SEM) image of a nitride phosphor according to Comparative Example 1. [Figure 2] This figure shows an example of an SEM image of a nitride phosphor according to Example 1. [Figure 3] This figure shows an example of an SEM image of a nitride phosphor according to Comparative Example 2. [Figure 4] This figure shows an example of an SEM image of a nitride phosphor according to Example 2. [Figure 5] This figure shows an example of an SEM image of a nitride phosphor according to Example 3. [Figure 6] This figure shows an example of an SEM image of a nitride phosphor according to Example 4. [Figure 7]This figure shows an example of an SEM image of a nitride phosphor related to Comparative Example 3. [Figure 8] This figure shows an example of an SEM image of a nitride phosphor according to Example 5. [Figure 9] This figure shows an example of an SEM image of a nitride phosphor according to Example 6. [Figure 10] This figure shows an example of an SEM image of a nitride phosphor according to Example 7. [Figure 11] This figure shows an example of an SEM image of a nitride phosphor according to Example 8. [Figure 12] This figure shows an example of an SEM image of a nitride phosphor related to Comparative Example 4. [Figure 13] This figure shows an example of an SEM image of a nitride phosphor according to Example 9. [Figure 14] This is a schematic cross-sectional view showing an example of a light-emitting device. [Modes for carrying out the invention]

[0010] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. In addition, the upper and lower limits of numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, in formulas representing the composition of phosphors, luminescent materials, or compounds, multiple elements separated by commas (,) mean that at least one of these multiple elements is contained in the composition. Also, in formulas representing the composition of phosphors, the element before the colon (:) represents the matrix crystal, and the element after the colon (:) represents the activating element. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color names of monochromatic light, etc., follow JIS Z8110. The full width at half maximum (FWHM) of a phosphor refers to the wavelength width (FWHM) of the emission spectrum where the emission intensity is 50% of the maximum emission intensity. Embodiments of the present invention will be described in detail below. However, the embodiments shown below are illustrative examples of nitride phosphors and light-emitting devices for realizing the technical concept of the present invention, and the present invention is not limited to the nitride phosphors and light-emitting devices shown below.

[0011] Nitride phosphors The nitride phosphor contains in its composition at least one Group 2 element selected from the group consisting of Mg, Ca, Sr, and Ba, along with Eu, Si, Al, and N. In its composition, the ratio of the total molar content of Group 2 elements and Eu to the molar content of Al may be, for example, 0.8 to 1.1, the ratio of the molar content of Eu to the molar content of Al may be, for example, 0.002 to 0.08, the ratio of the molar content of Si to the molar content of Al may be, for example, 0.8 to 1.2, and the ratio of the total molar content of Si and Al to the molar content of Al may be, for example, 1.8 to 2.2. The nitride phosphor may have an average aspect ratio, which is the ratio of the minor axis to the major axis, of 0.72 to 0.77. The nitride antibody may have an average circularity of 0.82 to 0.92.

[0012] Nitride phosphors, having a specific composition and a particle shape defined by a specific range of aspect ratio and average circularity, can achieve high luminous flux when used in light-emitting devices. This is because, for example, when nitride phosphors are uniformly dispersed in the resin of the wavelength conversion component constituting the light-emitting device and evenly distributed within the wavelength conversion component, light emission loss caused by the reabsorption of light emitted from the light-emitting element, as well as light emitted from the nitride phosphors and other phosphors, by the nitride phosphors can be reduced.

[0013] The nitride phosphor contains a Group 2 element including at least one selected from the group consisting of Mg, Ca, Sr, and Ba in its composition. The Group 2 element contained in the composition of the nitride phosphor may include at least one of Ca and Sr, and may include at least Ca. The ratio of the total molar content of Ca and Sr to the total molar content of the Group 2 element contained in the composition of the nitride phosphor may be, for example, 0.8 or more, preferably 0.9 or more, and may consist substantially of only Ca and Sr. Here, "substantially" means not excluding Group 2 elements other than Ca and Sr that are inevitably mixed in. The ratio of the molar content of Group 2 elements other than Ca and Sr to the total molar content of Ca and Sr may be, for example, 0.1 or less, preferably 0.08 or less.

[0014] In the composition of the nitride phosphor, the ratio of the total molar content of the Group 2 element and Eu to the molar content of Al may preferably be 0.94 or more and 1.1 or less, or 0.95 or more and 1.05 or less. In the composition of the nitride phosphor, the ratio of the molar content of Eu to the molar content of Al may preferably be 0.002 or more and 0.08 or less, or 0.004 or more and 0.07 or less. In the composition of the nitride phosphor, the ratio of the molar content of Si to the molar content of Al may preferably be 0.8 or more and 1.2 or less, or 0.9 or more and 1.1 or less. In the composition of the nitride phosphor, the ratio of the total molar content of Si and Al to the molar content of Al may preferably be 1.8 or more and 2.2 or less, or 1.9 or more and 2.1 or less. The composition of the nitride phosphor can be determined by fluorescent X-ray (XRF) analysis.

[0015] ...The nitride phosphor may have, for example, a composition represented by the following formula (I). M a s Sr t Eu u Si v Al w N x [[ID=]]

[0016] In formula (I), M ... ais a group 2 element containing at least one selected from the group consisting of Mg, Ca, and Ba, and preferably contains at least Ca. s, t, u, v, w, and x may satisfy 0≦s<1, 0≦t<1, 0.002≦u≦0.08, 0.8≦s+t+u≦1.1, 0.8≦v≦1.2, 0.8≦w≦1.2, 1.8≦v+w≦2.2, and 2.5≦x≦3.2. Also, s, t, and u may satisfy 0.94≦s+t+u≦1.10.

[0017] The nitride phosphor may have an average aspect ratio (ratio of minor axis to major axis) of 0.72 to 0.77, preferably 0.73 or higher, and may be 0.76 or lower, or 0.75 or lower. The average aspect ratio of the nitride phosphor is the arithmetic mean of the ratio of minor axis to major axis of 10 arbitrarily selected nitride phosphor particles. The selected nitride phosphor particles are selected from images taken by observation with an optical microscope, excluding phosphor particles that overlap each other, phosphor particles whose overall shape is not captured, and phosphor particles that are clearly too small. The major axis is the maximum value of the line segment connecting two points on the outer edge of the nitride phosphor particle, and the minor axis is the maximum length of the line segment connecting two intersection points between a line perpendicular to the major axis and the outer edge of the particle. Specifically, the aspect ratio of the nitride phosphor is measured using a particle image imaging analyzer, Morphologi G3S (manufactured by MALVERN PANALYTICAL). Furthermore, the average aspect ratio of nitride phosphors is evaluated by rounding the value to the third decimal place, resulting in a value with two decimal places.

[0018] The nitride phosphor may have an average circularity of 0.82 or more and 0.92 or less, preferably 0.85 or more, or 0.87 or more, and may be 0.91 or less, or 0.90 or less. The average circularity of the nitride phosphor is the arithmetic mean of the circularity of 10 arbitrarily selected nitride phosphor particles. The selected nitride phosphor particles are selected from images taken by observation with an optical microscope, excluding phosphor particles that overlap each other, phosphor particles whose overall shape is not captured, and phosphor particles that are clearly too small. The circularity of each nitride phosphor particle is calculated from the projected area S and the perimeter L of the particle using the following formula. Specifically, the circularity of the nitride phosphor particles is measured using a particle image imaging analyzer, Morphologi G3S (manufactured by MALVERN PANALYTICAL). The average circularity of nitride phosphors is evaluated by rounding the value to two decimal places, with the third decimal place being rounded off.

[0019] Circularity = 4πS / L 2

[0020] The volume-average particle size (Dm) of the nitride phosphor may be, for example, 20 μm or more and 40 μm or less, preferably 23 μm or more, or 25 μm or more, and may be 36 μm or less, from the viewpoint of luminescence efficiency. Nitride phosphors tend to have higher excitation light absorption and luminescence efficiency when the volume-average particle size is larger. Thus, by applying nitride phosphors with excellent optical properties to the light-emitting device described later, the luminescence efficiency of the light-emitting device is further improved. Furthermore, it is preferable that nitride phosphor particles having the above-mentioned volume-average particle size value are frequently contained in the nitride phosphor. That is, it is preferable that the particle size distribution is distributed within a narrow range. By using nitride phosphors with small variations in particle size distribution, color unevenness is further suppressed, and a light-emitting device with better color tone can be obtained. The logarithmic standard deviation (σlog) of the volume-based particle size distribution of the nitride phosphor may be, for example, 0.25 or more and less than 0.38, preferably 0.37 or less, or 0.36 or less, and may be 0.26 or more.

[0021] The volume-average particle size of nitride phosphors is determined as the particle size corresponding to 50% of the volume accumulation from the smallest diameter side in the volume-based particle size distribution curve obtained by measuring the particle size distribution using laser diffraction scattering. Specifically, it is a value obtained by measuring the volume-based particle size distribution using a laser diffraction particle size distribution analyzer (for example, MALVERN PANALYTICAL, product name: MASTER SIZER3000).

[0022] The nitride phosphor may have an average particle size (D) obtained by air permeation, for example, 20 μm or more and 30 μm or less, preferably 21 μm or more, or 22 μm or more, and 25 μm or less, from the viewpoint of luminescence efficiency. The average particle size obtained by air permeation may be FSSS No. (Fisher Sub-Sieve Sizer's No.), and is measured, for example, using a Fisher Sub-Sieve Sizer Model 95 manufactured by Fisher Scientific.

[0023] The nitride phosphor has a ratio (D / Dm) of the average particle size (D) obtained by the air permeation method to the volume average particle size (Dm) which may be 0.75 or more and 0.92 or less, preferably 0.76 or more, or 0.77 or more, and may be 0.91 or less, or 0.90 or less, from the viewpoint of luminescence efficiency.

[0024] The nitride phosphor may have an emission peak wavelength in the range of, for example, 600 nm to 675 nm. The emission peak wavelength of the nitride phosphor is preferably 605 nm or more, or 610 nm or more, and preferably 660 nm or less, or 640 nm or less. The full width at half maximum (FWHM) of the emission peak of the nitride phosphor is, for example, 70 nm to 78 nm, and preferably 76 nm or less, or 74 nm or less. When the FWHM of the emission peak is within the above range, the luminous flux of the light-emitting device tends to improve further.

[0025] Method for manufacturing nitride phosphors A method for producing nitride phosphors may include heat-treating a raw material mixture containing a group 2 element source, a europium source, a silicon source, and an aluminum source in a nitrogen-containing atmosphere at a temperature of 1800°C to 2100°C to obtain a heat-treated product. The heat-treated product may contain nitride phosphors, and the nitride phosphor produced may be the nitride phosphor described above.

[0026] The Group 2 element in the Group 2 element source contained in the raw material mixture is at least one selected from the group consisting of Mg, Ca, Sr, and Ba, and may contain at least one of Ca and Sr, and may contain at least Ca.

[0027] Examples of Group 2 element sources include metal compounds containing Group 2 elements, elemental metals of Group 2 elements, and alloys containing Group 2 elements. Examples of metal compounds containing Group 2 elements include hydrides, oxides, hydroxides, nitrides, oxynitrides, chlorides, amide compounds, and imide compounds containing Group 2 elements, with hydrides, nitrides, amide compounds, and imide compounds being preferred. The Group 2 element source may also contain Li, Na, K, B, Al, etc.

[0028] The Group 2 element source may include a metal compound containing at least one Group 2 element, and the Group 2 element metal compound may include a hydride containing at least one Group 2 element (hereinafter also referred to as a Group 2 element hydride) and at least one compound selected from the group consisting of amide compounds and imide compounds containing Group 2 elements. By including a Group 2 element hydride in the Group 2 element source, it is possible to obtain a nitride phosphor with a crystal structure with few defects, accelerated crystal growth, and a relatively large particle size. Furthermore, when the raw material mixture of Group 2 element hydrides is heat-treated, the hydrogen contained in the hydride reacts with oxygen in the heat treatment atmosphere to form water, which is easily released outside the reaction system. Therefore, oxygen and other elements are less likely to be incorporated into the composition of the resulting nitride phosphor, and it is possible to obtain a nitride phosphor with a low content of elements other than the target composition, such as oxygen, which may cause a decrease in luminescence properties.

[0029] Amide compounds and imide compounds containing Group 2 elements (hereinafter also referred to as Group 2 element amide compounds and imide compounds) are compounds in which the mass ratio of nitrogen contained in one molecule is higher than that of nitrides containing Group 2 elements. By using at least one of the amide compounds and imide compounds containing Group 2 elements as a Group 2 element source, Group 2 elements can be supplied, and nitrogen can also be sufficiently supplied to approach the theoretical composition, resulting in a crystalline structure with few defects, accelerated crystal growth, and a relatively large particle size nitride phosphor can be obtained.

[0030] Examples of hydrides of Group 2 elements include MgH2, CaH2, SrH2, BaH2, (Sr,Ca)H2, (Sr,Ca,Eu)H2, etc., and may contain at least one selected from the group consisting of these. Examples of amide and imide compounds of Group 2 elements include (Sr(NH2)2, Ca(NH2)2, (Sr,Ca)(NH2)2, (Sr,Ca,Eu)(NH2)2, SrNH, CaNH, (Sr,Ca)NH, (Sr,Ca,Eu)NH, etc., and may contain at least one selected from the group consisting of these.

[0031] In a Group 2 element source, the mass-based content of Group 2 element hydrides relative to the total of Group 2 element hydrides, amide compounds, and imide compounds may be, for example, in the range of 20% to 80% by mass, preferably in the range of 25% to 75% by mass. When the hydride content is within the above range, Group 2 elements and nitrogen elements can be sufficiently supplied as elements constituting the crystal structure, resulting in a nitride phosphor with a crystal structure that suppresses defects, accelerated crystal growth, a relatively large particle size, and excellent luminescence intensity.

[0032] Hydrides, amide compounds, and imide compounds containing Group 2 elements may be obtained through acquisition or other means, or they may be manufactured. Hydrides can be produced, for example, by heat-treating elemental Group 2 metals in an inert atmosphere containing hydrogen. Amide compounds and imide compounds can be produced by heat-treating elemental Group 2 metals in an atmosphere containing nitrogen and hydrogen. The purity of the hydrides, amide compounds, and imide compounds containing Group 2 elements may be, for example, 95% by mass or more, preferably 98% by mass or more, 99% by mass or more, or 99.5% by mass or more, from the viewpoint of reducing impurities contained in the resulting nitride phosphors.

[0033] The Group 2 element source may include other compounds containing Group 2 elements other than hydrides, amide compounds, and imide compounds containing Group 2 elements. Examples of other compounds containing Group 2 elements include oxides, hydroxides, nitrides, oxynitrides, and chlorides, and may include at least nitrides. The content of other compounds other than hydrides, amide compounds, and imide compounds in the Group 2 element source may be, for example, 10% by mass or less, preferably 5% by mass or less, 3% by mass or less, 2% by mass or less, or 1% by mass or less.

[0034] Examples of europium sources included in the raw material mixture include europium compounds, elemental europium metal, and europium alloys. Examples of europium compounds include europium-containing oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides. Specifically, examples of europium compounds include europium oxide (Eu2O3), europium nitride (EuN), and europium fluoride (EuF3), and the mixture may contain at least one selected from this group. Europium nitride (EuN) is composed only of the elements of the desired phosphor composition, and therefore can more effectively suppress the inclusion of impurities. In addition, europium oxide (Eu2O3) and europium fluoride (EuF3) can act as fluxes and are preferably used. Europium compounds may be used individually or in combination of two or more.

[0035] Europium compounds may be obtained by means of acquisition or other means, or desired europium compounds may be manufactured and used. For example, europium nitride can be obtained by pulverizing europium as a raw material in an inert gas atmosphere, and then nitriding the resulting powder by heat treatment in a nitrogen atmosphere or an ammonia atmosphere. The average particle size of the pulverized europium may be, for example, 0.1 μm or more and 10 μm or less. The heat treatment temperature may be, for example, 600°C or more and 1200°C or less, and the heat treatment time may be, for example, 1 hour or more and 20 hours or less. The obtained europium nitride may be subjected to pulverization treatment in an inert gas atmosphere, for example.

[0036] The raw material mixture may be a mixture in which at least a portion of the europium source is replaced with metallic compounds, elemental metals, or alloys of rare earth elements such as scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Examples of metallic compounds include oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides.

[0037] The purity of the europium source (e.g., europium compound) may be, for example, 95% by mass or higher, and preferably 99.5% by mass or higher. By setting the purity to a predetermined value or higher, the adverse effects of the presence of impurities can be reduced, and the luminescence intensity of the nitride phosphor can be further improved.

[0038] Examples of silicon sources included in the raw material mixture include silicon compounds, elemental silicon, and silicon alloys. Examples of silicon compounds include silicon-containing oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides. Specifically, examples of silicon compounds include silicon oxide, silicon nitride, silicon oxynitride, and silicates. It is preferable to use at least one selected from this group, with silicon nitride being more preferable. Since silicon nitride is composed only of the elements of the desired phosphor composition, it can more effectively suppress the inclusion of impurities. Compared to silicon compounds containing, for example, oxygen and hydrogen, silicon nitride can reduce the influence of these elements, and compared to elemental metals, a nitriding reaction is unnecessary. Silicon compounds may be used individually or in combination of two or more.

[0039] Silicon compounds may be obtained by means of acquisition or other means, or desired silicon compounds may be manufactured and used. For example, silicon nitride can be obtained by pulverizing silicon as a raw material in an inert gas atmosphere and nitriding the resulting powder by heat treatment in a nitrogen atmosphere. The heat treatment temperature may be, for example, 800°C to 2000°C, and the heat treatment time may be, for example, 1 hour to 20 hours. The obtained silicon nitride may be subjected to pulverization treatment in an inert gas atmosphere, for example.

[0040] The raw material mixture may be a mixture in which part of the silicon source is replaced with metal compounds, elemental metals, alloys, etc., of Group 4 or Group 14 elements such as germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), and hafnium (Hf). Examples of metal compounds include oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides.

[0041] The purity of the silicon source (e.g., silicon compound) may be, for example, 95% by mass or higher, and preferably 99% by mass or higher. By setting the purity to a predetermined value or higher, the influence of impurities can be reduced, and the luminescence intensity of the nitride phosphor can be further improved.

[0042] Examples of aluminum sources included in the raw material mixture include aluminum compounds, elemental aluminum metal, and aluminum alloys. Examples of aluminum compounds include aluminum oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides. Specifically, examples of aluminum compounds include aluminum nitride (AlN), aluminum oxide (Al2O3), and aluminum hydroxide (Al(OH)3). It is preferable to use at least one selected from this group, with aluminum nitride being more preferable. Since aluminum nitride is composed only of the elements of the desired phosphor composition, it can more effectively suppress the inclusion of impurities. Compared to aluminum compounds containing, for example, oxygen and hydrogen, aluminum nitride can reduce the influence of these elements, and compared to elemental metals, a nitriding reaction is unnecessary. Aluminum compounds may be used individually or in combination of two or more.

[0043] Aluminum compounds may be obtained through acquisition or other means, or they may be manufactured to produce the desired aluminum compound. For example, aluminum nitride can be produced by direct nitriding of aluminum or the like.

[0044] The raw material mixture may be a mixture in which at least a portion of the aluminum source is replaced with a metal compound, elemental metal, alloy, etc., of a Group 13 element such as gallium (Ga) or indium (In), a Group 5 element such as vanadium (V), a Group 6 element such as chromium (Cr), or a Group 9 element such as cobalt (Co). Examples of metal compounds include oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides.

[0045] The purity of the aluminum source (e.g., an aluminum compound) may be, for example, 95% by mass or higher, and preferably 99% by mass or higher. By setting the purity to a predetermined value or higher, the influence of impurities can be reduced, and the luminescence intensity of the phosphor can be further improved.

[0046] The raw material mixture may further contain at least one metal fluoride. The inclusion of at least one metal fluoride in the raw material mixture tends to yield nitride phosphors exhibiting higher luminescence intensity.

[0047] The metal fluoride may preferably include at least one selected from the group consisting of metal fluorides containing Group 2 elements, metal fluorides containing rare earth elements, metal fluorides containing Group 4 or Group 14 elements, and metal fluorides containing Group 13 elements.

[0048] The group 2 element in the metal fluoride may include at least one selected from the group consisting of Mg, Ca, Sr, and Ba, preferably at least one of Sr and Ca, and more preferably at least Ca. When the raw material mixture includes at least one metal fluoride containing a group 2 element, the metal fluoride containing the group 2 element may be part of the group 2 element source. That is, part of the group 2 element source may be substituted with a metal fluoride containing a group 2 element.

[0049] When a portion of the Group 2 element source is replaced with a metal fluoride containing a Group 2 element, the ratio of the molar amount of the metal fluoride containing a Group 2 element to the molar amount of the Group 2 element source may be, for example, 0.05 or more and less than 1, preferably 0.08 or more, or 0.1 or more, and preferably 0.8 or less, 0.6 or less, or 0.4 or less.

[0050] The rare earth element in the metal fluoride may include at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and preferably Eu. When the raw material mixture includes a metal fluoride containing a rare earth element, the metal fluoride containing the rare earth element may be part of the europium source. That is, part of the europium source may be replaced by a metal fluoride containing a rare earth element.

[0051] When a portion of the europium source is replaced with a metal fluoride containing a rare earth element, the ratio of the number of moles of the metal fluoride containing a rare earth element to the molar amount of the europium source may be, for example, 0.05 or more and less than 1, preferably 0.08 or more, or 0.1 or more, and preferably 0.8 or less, 0.6 or less, or 0.4 or less.

[0052] The Group 4 or Group 14 element in the metal fluoride may include at least one element selected from the group consisting of Ge, Sn, Ti, Zr, and Hf. If the raw material mixture contains a metal fluoride containing a Group 4 or Group 14 element, the metal fluoride containing the Group 4 or Group 14 element may be part of the silicon source. That is, part of the silicon source may be replaced by a metal fluoride containing a Group 4 or Group 14 element.

[0053] When a portion of the silicon source is replaced with a metal fluoride containing a Group 4 or Group 14 element, the ratio of the number of moles of the metal fluoride containing a Group 4 or Group 14 element to the molar amount of the silicon source may be, for example, 0.05 or more and less than 1, preferably 0.08 or more, or 0.1 or more, and preferably 0.8 or less, 0.6 or less, or 0.4 or less.

[0054] The Group 13 element in the metal fluoride may include at least one selected from the group consisting of Al, Ga, and In, and preferably may include Al. When the raw material mixture includes a metal fluoride containing a Group 13 element, the metal fluoride containing the Group 13 element may be part of the aluminum source. That is, part of the aluminum source may be substituted with a metal fluoride containing a Group 13 element.

[0055] When a portion of the aluminum source is replaced with a metal fluoride containing a group 13 element, the ratio of the number of moles of the metal fluoride containing a group 13 element to the molar amount of the aluminum source may be, for example, 0.05 or more and less than 1, preferably 0.08 or more, or 0.1 or more, and preferably 0.8 or less, 0.6 or less, or 0.4 or less.

[0056] The amount of metal fluoride in the raw material mixture is such that the molar ratio of fluorine atoms to aluminum is, for example, 0.01 to 0.3. Preferably, the molar ratio is 0.01 to less than 0.3, more preferably 0.015 to 0.2, even more preferably 0.02 to 0.15, and still more preferably 0.025 to 0.1. By setting the molar ratio above the lower limit, the flux effect can be sufficiently obtained. If a certain amount of flux is included, the flux effect will saturate, and no further effect can be expected even if more is included. Therefore, by setting it below the upper limit, the flux effect can be obtained without including more flux than necessary.

[0057] The purity of the metal fluoride may be, for example, 95% by weight or more, and preferably 99% by weight or more. By setting the purity to a predetermined value or higher, the influence of impurities can be reduced, and the luminescence intensity of the phosphor can be further improved. The metal fluoride containing the Group 2 source may further contain Li, Na, K, B, Al, etc. The metal fluoride may be obtained by acquisition or other means, or the desired metal fluoride may be manufactured and used.

[0058] If the raw material mixture contains metal fluorides, it may further contain fluxes such as other halides in addition to the metal fluorides. Examples of halides include chlorides and fluorides of rare earths and alkali metals. If the raw material mixture contains fluxes, their content is, for example, 20% by mass or less, preferably 10% by mass or less, and more preferably 1% by mass or less, relative to the metal fluorides.

[0059] The raw material mixture may further contain a nitride phosphor prepared separately, if necessary. If the raw material mixture contains a nitride phosphor, its content can be, for example, 1% by mass or more and 50% by mass or less of the total amount of the raw material mixture.

[0060] The raw material mixture can be prepared by mixing a Group 2 element source, a europium source, a silicon source, and an aluminum source in a predetermined quantitative ratio. The mixing ratio of each component in the raw material mixture may be, for example, such that the ratio of the total molar content of the Group 2 element and europium to the molar content of aluminum is 0.8 or more and 1.1 or less, preferably 0.9 or more and 1.05 or less. Also, the ratio of the molar content of europium to the molar content of aluminum may be 0.002 or more and 0.08 or less, preferably 0.004 or more and 0.075 or less. The ratio of the molar content of silicon to the molar content of aluminum may be 0.8 or more and 1.2 or less, preferably 0.9 or more and 1.1 or less. The ratio of the total molar content of silicon and aluminum to the molar content of aluminum may be 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less.

[0061] The mixing ratio of each component in the raw material mixture may be selected, for example, such that s, t, u, v, w, and x in the following formula (Ia) satisfy the following requirements defined in formula (Ia). M a s Sr t Eu u Si v Al w N x (Ia)

[0062] In formula (Ia), M a is a Group 2 element containing at least one selected from the group consisting of Mg, Ca, and Ba. s, t, u, v, w, and x may satisfy 0 < s < 1, 0 ≤ t < 1, 0.002 ≤ u ≤ 0.08, 0.8 ≤ s + t + u ≤ 1.1, 0.8 ≤ v ≤ 1.2, 0.8 ≤ w ≤ 1.2, 1.8 ≤ v + w ≤ 2.2, 2.5 ≤ x ≤ 3.2. Also, s, t, and u may satisfy 0.94 ≤ s + t + u ≤ 1.10.

[0063] The raw material mixture can be obtained by weighing each component of the raw material mixture to the desired ratio, and then mixing the components using a ball mill, a Henschel mixer, a V-type blender, or a mortar and pestle. Mixing can be done dry, or wet by adding a solvent.

[0064] The desired nitride phosphor can be obtained by heat-treating the resulting raw material mixture. The heat treatment temperature of the raw material mixture may be, for example, in the range of 1200°C to 2200°C, preferably 1500°C or higher, 1800°C or higher, 1850°C or higher, or 1900°C or higher, and may be 2100°C or lower, 2080°C or lower, 2060°C or lower, or 2000°C or lower. By heat-treating the raw material mixture at a temperature above a predetermined value, europium can easily penetrate the crystal structure, promoting crystal growth and forming a phosphor with a relatively large particle size and excellent luminescence intensity. Furthermore, if the heat treatment temperature of the raw material mixture is below a predetermined temperature, the decomposition of the formed crystal structure is suppressed, and a nitride phosphor with a crystal structure with fewer defects can be obtained. The heat treatment of the raw material mixture can be carried out, for example, using a gas-pressurized electric furnace.

[0065] The heat treatment of the raw material mixture may be carried out at a single temperature or in multiple stages including two or more heat treatment temperatures. When heat treatment is carried out in multiple stages, for example, the first stage heat treatment may be carried out at 1200°C to 1600°C, preferably 1300°C to 1500°C, and then the temperature may be gradually increased to 1800°C to 2100°C, preferably 1850°C to 2050°C for the second stage heat treatment. Furthermore, the multi-stage heat treatment may include, for example, first heat treatment of the raw material mixture at a temperature of 1200°C to 1600°C, preferably 1300°C to 1500°C to obtain a first heat-treated product, and then second heat treatment of the first heat-treated product obtained by cooling at a temperature of 1800°C to 2100°C, preferably 1850°C to 2050°C to obtain a second heat-treated product. It may also include crushing, grinding, etc., of the first heat-treated product to obtain a pulverized product. Multi-stage heat treatment tends to yield nitride phosphors that exhibit higher luminescence intensity.

[0066] In the heat treatment of the raw material mixture, for example, the temperature is raised from room temperature to a predetermined temperature. The heating time is, for example, 1 hour or more and 48 hours or less, preferably 2 hours or more and 24 hours or less, and more preferably 3 hours or more and 20 hours or less. If the heating time is above the lower limit, the particle growth of the nitride phosphor tends to proceed sufficiently, and europium tends to penetrate more easily into the nitride phosphor crystal.

[0067] In the heat treatment of the raw material mixture, a holding time at a predetermined temperature may be provided. The holding time is, for example, 0.5 hours or more and 48 hours or less, preferably 1 hour or more and 30 hours or less, and more preferably 2 hours or more and 20 hours or less. By setting the holding time to be above the lower limit, uniform particle growth can be further promoted. Also, by setting the holding time to be below the upper limit, the decomposition of the phosphor can be further suppressed.

[0068] The cooling time from a predetermined temperature to room temperature during the heat treatment of the raw material mixture is, for example, 0.1 hours or more and 20 hours or less, preferably 1 hour or more and 15 hours or less, and more preferably 3 hours or more and 12 hours or less. A holding time at an appropriately selected temperature may be provided during the cooling from the predetermined temperature to room temperature. This holding time is adjusted, for example, to further improve the luminescence intensity of the nitride phosphor. The holding time at the predetermined temperature during cooling is, for example, 0.1 hours or more and 20 hours or less, preferably 1 hour or more and 10 hours or less. The temperature during the holding time is, for example, 1000°C or more and less than 1800°C, preferably 1200°C or more and 1700°C or less.

[0069] The atmosphere used in the heat treatment of the raw material mixture may be, for example, an atmosphere containing nitrogen gas, and preferably a substantially nitrogen gas atmosphere. By using a nitrogen gas atmosphere, silicon contained in the raw material can be nitrided. Furthermore, the decomposition of nitrided raw materials and phosphors can be suppressed. When the atmosphere used in the heat treatment of the raw material mixture contains nitrogen gas, in addition to nitrogen gas, other gases such as hydrogen, argon and other noble gases, carbon dioxide, carbon monoxide, oxygen, and ammonia may also be included. The nitrogen gas content in the atmosphere used in the heat treatment of the raw material mixture may be, for example, 90% by volume or more, and preferably 95% by volume or more. By keeping the content of gases containing elements other than nitrogen below a predetermined value, the decrease in the luminescence intensity of the phosphor due to the formation of impurities by these gas components tends to be suppressed.

[0070] The pressure used in the heat treatment of the raw material mixture can be, for example, atmospheric pressure to 200 MPa. From the viewpoint of suppressing the decomposition of the nitride phosphor produced, a higher pressure is preferable, and as a gauge pressure, it may be in the range of, for example, 0.1 MPa to 200 MPa, and preferably in the range of 0.6 MPa to 1.2 MPa, where there are fewer constraints on industrial equipment.

[0071] The heat treatment of the raw material mixture can be performed by filling the mixture into a crucible or boat made of a material selected from the group consisting of carbon materials such as graphite, boron nitride (BN), alumina (Al2O3), molybdenum (Mo), and tungsten (W), and then performing the heat treatment. From the viewpoint of suppressing the inclusion of impurities in the resulting nitride phosphor, a crucible or boat made of boron nitride or tungsten may be preferably used for the heat treatment of the raw material mixture.

[0072] In one embodiment, the heat treatment of the raw material mixture may be carried out in a sealed container made of tungsten. This allows for the efficient production of nitride phosphors that can exhibit higher luminescence intensity. The sealed container used for heat treatment of the raw material mixture may be substantially made of tungsten. Here, "substantially" means that impurities that inevitably become present are not excluded.

[0073] Here, a sealed container refers to a container that can prevent solid foreign matter from entering under normal handling, transportation, or storage conditions (for example, Article 37 of the General Rules of the Japanese Pharmacopoeia). A sealed container consists of, for example, a container body with an opening and a lid that seals the opening of the container body, and can prevent solids from entering or leaving under heat treatment conditions. In addition, in a sealed container, it is sufficient that the entry and exit of gases under heat treatment conditions is suppressed, but it is not necessary to completely prevent it. The shape of the container body of a sealed container may, for example, have a bottom and a wall surrounding the bottom, with the upper part opposite the bottom being an opening. The shape of the container body may be cylindrical, polygonal prism, square, etc. In a tungsten sealed container, it is sufficient that at least the part that comes into contact with the raw material mixture is substantially made of tungsten, and preferably the entire sealed container may be substantially made of tungsten.

[0074] The amount of the raw material mixture contained in the sealed container may be, for example, 60% to 100% of the capacity of the sealed container, and preferably 75% to 99% of the capacity.

[0075] The heat-treated material obtained by heat-treating the raw material mixture may be subjected to sizing operations such as grinding and classification. The sizing process yields phosphor particles with the desired particle size. Specifically, the obtained heat-treated material is roughly ground (also called crushed) and then ground to a predetermined particle size using a general grinder such as a ball mill, jet mill, or vibratory mill. If particles of different particle sizes exist after grinding, classification may be performed to obtain nitride phosphors of the desired particle size. The calcined material before or after classification may be washed by contacting it with deionized water, an acidic solution, or a basic solution to remove thermal decomposition products adhering to the surface of the calcined material.

[0076] One embodiment of a method for producing a nitride phosphor may include: first heat-treating a raw material mixture containing a group 2 element source, a europium source, a silicon source, and an aluminum source in a sealed tungsten container at a temperature of 1200°C to 1600°C to obtain a first heat-treated product; and second heat-treating the first heat-treated product in a sealed tungsten container at a temperature of 1800°C to 2100°C to obtain a second heat-treated product, wherein the group 2 element source may include a hydride containing at least one group 2 element and at least one selected from the group consisting of amide compounds and imide compounds containing group 2 elements.

[0077] Light-emitting device One embodiment of the light-emitting device may include a fluorescent member containing the nitride phosphor described above, and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm. The light-emitting device 100 will be described with reference to Figure 14. The light-emitting device 100 is an example of a surface-mount type light-emitting device. The light-emitting device 100 includes a light-emitting element 10 made of a gallium nitride-based compound semiconductor having an emission peak wavelength in the range of 380 nm to 470 nm, and a molded body 40 on which the light-emitting element 10 is mounted. The molded body 40 is formed by integrally molding a first lead 20 and a second lead 30 and a resin part 42. The molded body 40 has a recess with a bottom surface and sides, and the light-emitting element 10 is mounted on the bottom surface of the recess. The light-emitting element 10 has a pair of positive and negative electrodes, and the pair of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30, respectively, via wires 60. The light-emitting element 10 is covered with a fluorescent member 50. The fluorescent component 50, for example, contains a phosphor 70 that converts the wavelength of light from the light-emitting element 10 and a resin.

[0078] The emission peak wavelength of the light-emitting element 10 is preferably within the range of 380 nm to 470 nm, or 400 nm to 460 nm. By using a light-emitting element 10 having an emission peak wavelength within this range as a light source, it is possible to configure a light-emitting device 100 that emits mixed light of light from the light-emitting element 10 and fluorescence from the fluorescent member 50. Furthermore, since a portion of the light emitted from the light-emitting element 10 can be effectively utilized as part of the light emitted to the outside from the light-emitting device 100, a light-emitting device 100 with high luminous efficiency can be obtained.

[0079] The full width at half maximum of the emission spectrum of the light-emitting element 10 can be, for example, 30 nm or less. It is preferable to use a semiconductor light-emitting element, for example, one made of a nitride-based semiconductor, as the light-emitting element. By using a semiconductor light-emitting element as the excitation light source, a stable light-emitting device can be obtained that is highly efficient, has high linearity of output to input, and is resistant to mechanical shock.

[0080] The fluorescent component 50 includes at least a nitride phosphor and may include other phosphors, resins, etc., as needed. In addition to the nitride phosphor, the fluorescent component may include other phosphors other than the nitride phosphor. By including other phosphors in the fluorescent component, a light-emitting device can be configured that emits a mixed color of light emitted by a light-emitting element and the nitride phosphor and the other phosphors.

[0081] Other phosphors include, for example, phosphors having compositions represented by any of the following formulas (IIa) to (IIi). It is preferable to include at least one phosphor having a composition represented by a formula selected from the group consisting of these, and more preferably at least one phosphor having a composition represented by formula (IIa), (IIb), (IIc), (IId), (IIe), (IIg), (IIh), or (IIi). This is because including these other phosphors results in a light-emitting device with high color rendering and luminous efficiency. The light-emitting device may contain one of the other phosphors alone or a combination of two or more.

[0082] (Y,Gd,Tb,Lu)3(Al,Ga)5O 12 :Ce (IIa) (Ca,Sr,Ba)2SiO4:Eu (IIb) Si 6-p Al p OpN 8-p :Eu(0 <p≦4.2) (IIc) (Ca,Sr)8MgSi4O 16 (F,Cl,Br)2:Eu (IId) (La,Y,Gd,Lu)3Si6N 11 :Ce (IIe) (Ca,Sr,Ba)2Si5N8:Eu (IIg) (Ca,Sr,Ba)LiAl3N4:Eu (IIh) (Ca, Sr, Ba) 10 (PO4)6(F,Cl,Br)2:Eu (IIi)

[0083] Examples of other phosphors include phosphors having a composition represented by any of the following formulas (IIj) and (IIk), and it is also preferable to include at least one phosphor having a composition represented by a formula selected from the group consisting of these. By including these other phosphors, a light-emitting device with high color rendering properties and luminous efficiency can be obtained, which is more preferable.

[0084] A 1 c [M 1 1-b Mn b F d (IIj) A 2 f [M 2 1-e Mn e F g (IIk)

[0085] In formula (IIj), A<000,000,038> includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 1 includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 elements and Group 14 elements. b satisfies 0 < b < 0.2, and c is the absolute value of the charge of the [M 1 1-b Mn b F d ion, and d satisfies 5 < d < 7.

[0086] In formula (IIk), A<00,000,044>includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 2 includes at least Si and Al, and may further include at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. e satisfies 0 < e < 0.2, and f is the absolute value of the charge of the [M 2 1-e Mn e F g ion, and g satisfies 5 < g < 7.

[0087] The average particle size of the other phosphors may be, for example, 2 μm to 35 μm, preferably 5 μm to 30 μm. If the average particle size of the other phosphors is above the lower limit, the absorption rate of light from the excitation light source is increased, and emission with a desired chromaticity and higher emission intensity can be obtained. Furthermore, if the average particle size of the other phosphors is below the upper limit, the workability in the manufacturing process of the light-emitting device can be improved when other phosphors are included in the fluorescent component of the light-emitting device.

[0088] The fluorescent component 50 may include at least one resin in addition to the nitride phosphor. Examples of resins include epoxy resin and silicone resin.

[0089] The fluorescent component 50 may further contain other components as needed in addition to the nitride phosphor. Examples of other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, as well as light stabilizers and colorants. When the fluorescent component contains other components, for example, fillers, the content of these fillers can be 0.01 to 20 parts by mass per 100 parts by mass of resin.

[0090] The invention relating to this disclosure may encompass, for example, the following embodiments: [1] A group 2 element comprising at least one selected from the group consisting of Mg, Ca, Sr, and Ba, along with Eu, Si, Al, and N, In the above composition, the ratio of the total molar content of the Group 2 elements and Eu to the molar content of Al is 0.8 or more and 1.1 or less, the ratio of the molar content of Eu is 0.002 or more and 0.08 or less, the ratio of the molar content of Si is 0.8 or more and 1.2 or less, and the ratio of the total molar content of Si and Al is 1.8 or more and 2.2 or less. A nitride phosphor having an average aspect ratio (ratio of minor axis to major axis) of 0.72 or more and 0.77 or less, and an average circularity of 0.82 or more and 0.92 or less.

[0091] [2] The nitride phosphor described in [1], wherein the volume average particle size is 20 μm or more and 40 μm or less.

[0092] [3] The nitride phosphor according to [1] or [2], wherein the ratio of the average particle size obtained by the air permeation method to the volume average particle size is 0.75 or more and 0.92 or less.

[0093] [4] A nitride phosphor according to any one of [1] to [3], wherein the logarithmic standard deviation of the particle size distribution based on volume of particle size is 0.25 or more and less than 0.38.

[0094] [5] A nitride phosphor according to any one of [1] to [4] having a composition represented by the following formula (I).

[0095] M a s Sr t EU u Si v Al w N x (I)

[0096] In formula (I), M a is a group 2 element comprising at least one element selected from the group consisting of Mg, Ca, and Ba, where s, t, u, v, w, and x satisfy the following conditions: 0 ≤ s < 1, 0 ≤ t < 1, 0.002 ≤ u ≤ 0.08, 0.8 ≤ s + t + u ≤ 1.1, 0.8 ≤ v ≤ 1.2, 0.8 ≤ w ≤ 1.2, 1.8 ≤ v + w ≤ 2.2, and 2.5 ≤ x ≤ 3.2.

[0097] [6] The nitride phosphor described in [5], wherein s, t, and u in formula (I) satisfy 0.94 ≤ s + t + u ≤ 1.10.

[0098] A light-emitting device comprising a fluorescent member containing a nitride phosphor as described in any of [1] to [6] [7], and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm.

[0099] [8] The light-emitting device according to [7], further comprising at least one selected from the group consisting of phosphors having a composition represented by any of the following formulas.

[0100] (Y, Gd, Tb, Lu)3(Al, Ga)5O 12 :Ce (IIa) (Ca, Sr, Ba)2SiO4:Eu (IIb) Si 6-p Al p OpN 8-p :Eu(0 < p ≤ 4.2) (IIc) (Ca, Sr)8MgSi4O 16 (F, Cl, Br)2:Eu (IId) (La, Y, Gd, Lu)3Si6N 11 :Ce (IIe) (Ca, Sr, Ba)2Si5N8:Eu (IIg) (Ca, Sr, Ba)LiAl3N4:Eu (IIh) (Ca, Sr, Ba) 10 (PO4)6(F, Cl, Br)2:Eu (IIi)

[0101] [9] The light-emitting device according to [7] or [8], wherein the fluorescent member further includes at least one selected from the group consisting of phosphors having a composition represented by any of the following formulas.

[0102] A 1 c [M 1 1-b Mn b F d (IIj)

[0103] In formula (IIj), A 1 includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 1 includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 elements and Group 14 elements. b satisfies 0 < b < 0.2, and c is the absolute value of the charge of the [M 1 1-b Mn b F d ion, and d satisfies 5 < d < 7.

[0104] A 2 f [M 2 1-e Mn e F g (IIk)

[0105] In formula (IIk), A 2 includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 2 includes at least Si and Al, and may further include at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. e satisfies 0 < e < 0.2, and f is [M 2 1-e Mn e F g the absolute value of the charge of the ion, and g satisfies 5 < g < 7.

Examples

[0106] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0107] Reference Example 1 Preparation of Strontium Hydride (SrH2) Metallic sr was placed on an alumina boat in an inert (Ar) atmosphere glove box and heat-treated in a tubular furnace at 600°C for 12 hours under a hydrogen-containing argon atmosphere (Ar flow rate: 5 L / min, H2 flow rate: 2.5 L / min) to obtain a heat-treated product. Next, the obtained heat-treated product was coarsely ground and mixed with other heat-treated materials. The coarsely ground heat-treated product was again heat-treated in a hydrogen-containing argon atmosphere in the same manner as above. This heat treatment and coarse grinding was repeated four times. After that, the material was ground and classified using a mortar and pestle in an inert (Ar) atmosphere glove box to obtain the powder of Reference Example 1. The obtained powder was subjected to X-ray diffraction (XRD) spectrum measurement in an inert atmosphere using a sample-horizon type multi-purpose X-ray diffractometer (product name: Ultima IV, manufactured by Rigaku Corporation, X-ray source: CuKα rays (λ=1.5418 Å), tube voltage 40 kV, tube current 40 mA). From the X-ray diffraction spectrum of the obtained powder, it was confirmed that the powder obtained in Reference Example 1 was strontium hydride (SrH2).

[0108] Reference Example 2: Preparation of a Strontium Source Metallic sr was placed on an alumina boat in an inert (Ar) atmosphere glove box and heat-treated in a tubular furnace at 300°C for 12 hours in a hydrogen-containing nitrogen atmosphere (N2 flow rate: 21.5 L / min, H2 flow rate: 0.9 L / min) to obtain a heat-treated product. Next, the obtained heat-treated product was coarsely ground and mixed with other heat-treated materials. The coarsely ground heat-treated product was again heat-treated in a hydrogen-containing nitrogen atmosphere in the same manner as above. This heat treatment and coarse grinding was repeated three times. After that, the material was ground and classified using a mortar and pestle in an inert (Ar) atmosphere glove box to obtain the powder of Reference Example 2. The obtained powder was subjected to X-ray diffraction (XRD) spectrum measurement in an inert atmosphere using a sample-horizontal type multi-purpose X-ray diffractometer (manufactured by Rigaku Corporation, X-ray source: CuKα rays (λ=1.5418 Å), tube voltage 40 kV, tube current 40 mA, product name: Ultima IV). From the X-ray diffraction spectrum of the obtained powder, it was confirmed that the powder obtained in Reference Example 2 is a mixture of strontium imidide and strontium hydride (x(SrNH)+(1-x)(SrH2), where x=1 / 4; hereafter sometimes abbreviated as "Sr3N2").

[0109] Example 1 Using the powder from Reference Example 2 (x(SrNH)+(1-x)(SrH2), equivalent to x=1 / 4; Sr3N2), along with calcium nitride (Ca3N2), calcium fluoride (CaF2), europium nitride (EuN), aluminum nitride (AlN), and silicon nitride (Si3N4) as raw materials, each compound was weighed and mixed in an inert atmosphere glove box to obtain a raw material mixture, with a starting composition ratio of Ca(Ca3N2):Ca(CaF2):Sr:Eu:Al:Si:F = 0.021:0.009:0.965:0.005:1:1:0.009 for each element. The raw material mixture was then packed into a tungsten crucible, lidded, and sealed. A first-stage heat treatment was performed under nitrogen gas atmosphere conditions of a gauge pressure of 0.92 MPa, a heat treatment temperature of 1400°C, and a holding time of 3 hours to obtain a precursor. This precursor was homogenized by grinding in a glove box under an inert atmosphere, and then filled again into a tungsten crucible, which was then sealed with a lid. A second-stage heat treatment was performed under nitrogen gas atmosphere conditions of a gauge pressure of 0.92 MPa, a heat treatment temperature of 1950°C, and a holding time of 15 hours. Subsequently, the nitride phosphor powder of Example 1 was obtained by processing such as grinding, dispersion, and classification.

[0110] Comparative Example 1 Ca3N2, CaF2, SrN x Comparative Example 1 obtained a nitride phosphor powder in the same manner as in Example 1, except that the raw material mixture was obtained by using (equivalent to x=2 / 3; a mixture of Sr2N and SrN), AlN3, Si3N4, and EuN as raw materials, and the molar ratio of these as the amount charged was Ca(Ca3N2):Ca(CaF2):Sr:Eu:Al:Si:F = 0.009:0.021:0.965:0.005:1:1:0.042.

[0111] Examples 2 to 8 The nitride phosphor powders of Examples 2 to 8 were obtained in the same manner as in Example 1, except that the raw material mixture was prepared so that the molar ratio of each element in the raw material mixture matched the composition ratios shown in Table 1.

[0112] Comparative Examples 2 to 4 Except that a raw material mixture was obtained such that the molar ratio of each element in the raw material mixture became the charged composition ratio described in Table 1, powders of nitride phosphors of Comparative Examples 2 to 4 were obtained in the same manner as in Comparative Example 1.

[0113] Example 9 Except that the powder of Reference Example 1 (SrH2) was used instead of the powder of Reference Example 2 as the strontium source, and a raw material mixture was obtained such that the molar ratio of each element in the raw material mixture became the charged composition ratio described in Table 1, powders of nitride phosphors of Example 9 were obtained in the same manner as in Example 1.

[0114]

Table 1

[0115] Composition Analysis For the nitride phosphors of each Example and Comparative Example, analysis of each constituent element of the nitride phosphor was performed using a scanning fluorescent X-ray analysis (XRF) apparatus (manufactured by RIGAKU, product name: ZSX primusII), an ion chromatography (IC) apparatus (manufactured by Thermo Scientific Dionex, product name: Dionex Integrion HPIC), and an oxygen / nitrogen / hydrogen analyzer (manufactured by HORIBA, product name: EMGA-930), and the molar ratio of each element was calculated respectively. The molar ratio of each element was calculated with the molar ratio of Al contained in the composition being 1. The results are shown in Table 1.

[0116] [[ID=**26**]]Average Circularity The average circularity of the nitride phosphors obtained in each Example and Comparative Example was determined as follows. From the images taken by observation with an optical microscope, 10 particles were arbitrarily selected excluding the phosphor particles overlapping each other, the phosphor particles whose overall shape was not shown, and the image recognition parts of clearly fine phosphor particles. For the selected particles, using image processing software (manufactured by MALVERN PANALYTICAL, MORPHOLOGI G3S), the projected area (S(m 2The diameter and circumference (L(m)) were measured, and the circularity of each particle was calculated using the following formula. The arithmetic mean of the calculated circularity of each particle was calculated and rounded to the third decimal place to obtain the average circularity of the nitride phosphors obtained in each example and comparative example. The results are shown in Table 2. Circularity = 4πS / L 2

[0117] Average aspect ratio The average aspect ratio of the nitride phosphors obtained in each example and comparative example was determined as follows. From images taken by observation with an optical microscope, 10 particles were arbitrarily selected, excluding overlapping phosphor particles, phosphor particles whose overall shape was not captured, and phosphor particles that were clearly too small. For the selected particles, the major and minor diameters were measured using image processing software (MALVERN PANALYTICAL, MORPHOLOGI G3S), and the ratio of the minor diameter to the major diameter (minor diameter / major diameter) was calculated as the aspect ratio of each particle. The arithmetic mean of the calculated aspect ratios of each particle was calculated and rounded to the third decimal place to obtain the average aspect ratio of the nitride phosphors obtained in each example and comparative example. The results are shown in Table 2.

[0118] Powder measurement For each example and comparative example, the nitride phosphors obtained were measured using the air permeability method (FSSS method) to determine the specific surface area by utilizing the resistance of air flow, and then the average particle size was calculated. The average particle size measured by the air permeability method is also called the Fisher Sub-Sieve Sizer's Number. Specifically, using a Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific), under conditions of 25°C and 70% RH humidity, 1 cm³ of the nitride phosphors obtained in each example and comparative example was weighed, packed into a dedicated tubular container, and then dry air at a constant pressure was flowed through it. The specific surface area was read from the differential pressure, and the average particle size was calculated using the FSSS method. The results are shown in Table 2.

[0119] For the nitride phosphors obtained in each example and comparative example, the volume-based particle size distribution was measured using a laser diffraction particle size distribution analyzer (MALVERN PANALYTICAL, product name: MASTER SIZER3000). The volume-average particle size (median diameter: Dm) and logarithmic standard deviation (σlog) corresponding to the cumulative frequency from the smallest diameter side of the particle size distribution at 50% were calculated. The results are shown in Table 2. Table 2 also shows the ratio (D / Dm) of the average particle size (D) obtained by the air permeation method to the volume-average particle size (Dm).

[0120] For each example and comparative example, the nitride phosphors obtained were irradiated with light having an emission peak wavelength of 450 nm using a quantum efficiency measuring device (Otsuka Electronics Co., Ltd., product name: QE-2000), and their emission spectra were measured. From the obtained emission spectra, the chromaticity coordinates (x, y), luminance (Y), emission intensity (ENG), and full width at half maximum of the emission peak were measured. The results are shown in Table 2.

[0121] [Table 2]

[0122] SEM image A scanning electron microscope (SEM; Hitachi High-Technologies Corporation, product name: SU3500) was used to obtain SEM images of the nitride phosphors obtained in Examples 1 to 9 and Comparative Examples 1 to 4. Figure 1 is an SEM image of Comparative Example 1, and Figure 2 is an SEM image of the nitride phosphor of Example 1. Figure 3 is an SEM image of Comparative Example 2, and Figures 4 to 6 are SEM images of the nitride phosphors of Examples 2 to 4, respectively. Figure 7 is an SEM image of Comparative Example 3, and Figures 8 to 11 are SEM images of the nitride phosphors of Examples 5 to 8, respectively. Figure 12 is an SEM image of Comparative Example 4, and Figure 13 is an SEM image of the nitride phosphor of Example 9.

[0123] Compared to the nitride phosphor in the comparative example, the nitride phosphor obtained in the example was confirmed to be a large particle with good uniformity, exhibiting improved average circularity and average aspect ratio within the specified range, and having better σlog and D / Dm.

[0124] Fabrication of a light-emitting device Using the nitride phosphors obtained in each of the examples and comparative examples, first, second, and third light-emitting devices were fabricated as follows.

[0125] First Light-Emitting Device An LED chip made of a nitride semiconductor having an emission peak wavelength of 455 nm was prepared as a light-emitting element. As shown in FIG. 14, the light-emitting element 10 was disposed on the bottom surface of the concave mold 40, and the light-emitting element 10, the first lead 20, and the second lead 30 were connected by wires 60, respectively. The first phosphor (SCASN), which is a nitride phosphor obtained in Example 1 or Comparative Example 1, the second phosphor (GYAG), which is a phosphor having a composition of Y3(Al,Ga)5O 12 :Ce, the third phosphor (YAG), which is a phosphor having a composition of Y3Al5O 12 :Ce, and the fourth phosphor (KSF), which has a composition of K2[Si 1-b Mn b F6] (0 < b < 0.2), were combined at the mixing ratios shown in Table 3 so that the chromaticity coordinates (x, y) of the emission color were around x = 0.346 and y = 0.355 (around 5000 K in color temperature), added to a silicone resin, and mixed. The phosphors were dispersed in the silicone resin to obtain a composition for a wavelength conversion member. This composition for a wavelength conversion member was injected into the concave portion of the mold 40, and the silicone resin was cured to form a fluorescent member 50, thereby obtaining a first light-emitting device.

[0126] Second Light-Emitting Device The first phosphor (SCASN), which is a nitride phosphor obtained in Example 1 or Comparative Example 1, and the second phosphor, which is a phosphor having a composition of Y3Al5O 12 :Ce, were combined at the mixing ratios shown in Table 4 so that the chromaticity coordinates (x, y) of the mixed light emitted by the light-emitting device were around x = 0.563 and y = 0.416 (amber color), added to a silicone resin, and mixed. The phosphors were dispersed in the silicone resin to obtain a composition for a fluorescent member. A second light-emitting device was obtained in the same manner as the first light-emitting device, except for this.

[0127] Third Light-Emitting Device To 100 parts by mass of the silicone resin, the nitride phosphor obtained in Examples 1 to 10 or Comparative Examples 1 to 4 was added so as to have the phosphor content shown in Table 5, and after being mixed and dispersed, it was further defoamed to obtain a composition for a fluorescent member. A third light-emitting device was obtained in the same manner as the first light-emitting device, except for this.

[0128] Evaluation of the Light-Emitting Device [[ID=^6]]Regarding the light-emitting device obtained above, the relative luminous flux (%) was measured as follows.

[0129] Regarding the luminous flux of the first light-emitting device and the second light-emitting device, it was measured using an integrating total luminous flux measuring device. The relative luminous flux of the first light-emitting device is shown in Table 3, and the relative luminous flux of the second light-emitting intensity is shown in Table 4.

[0130] Regarding the chromaticity of the third light-emitting device, using an optical measurement system combining a multi-channel spectroscope and an integrating sphere, the chromaticity coordinates (x, y) in the chromaticity coordinate system of the CIE1931 chromaticity diagram were obtained. Also, in each Example and Comparative Example, specifically, the chromaticity coordinates (x, y) of five light-emitting devices were obtained, and the arithmetic mean value thereof was used as the chromaticity coordinates of the light-emitting devices in each Example and Comparative Example. Incidentally, the dominant wavelength of each light-emitting device is, in the chromaticity diagram of JIS Z8701, white chromaticity point W(x w = 0.33333, y w = 0.33333) and the chromaticity coordinates (x, y) of each light-emitting device were extended, and the wavelength of the point where it intersects the spectral locus on the chromaticity diagram was used.

[0131] The luminous flux of the third light-emitting device was measured using an integrating total luminous flux measuring device. The relative luminous flux of the light-emitting device using the nitride phosphor of Example 1 with the luminous flux of the light-emitting device using the nitride phosphor of Comparative Example 1 as a reference (100%), the relative luminous flux of the light-emitting devices using the nitride phosphors of Examples 2 to 4 with the luminous flux of the light-emitting device using the nitride phosphor of Comparative Example 2 as a reference (100%), the relative luminous flux of the light-emitting devices using the nitride phosphors of Examples 5 to 8 with the luminous flux of the light-emitting device using the nitride phosphor of Comparative Example 3 as a reference (100%), and the relative luminous flux of the light-emitting device using the nitride phosphor of Example 9 with the luminous flux of the light-emitting device using the nitride phosphor of Comparative Example 4 as a reference (100%) are shown in Table

[0132] [Table 3]

[0133] [Table 4]

[0134] [Table 5]

[0135] As shown in Tables 3 to 5, the luminous flux of the light-emitting device using nitride phosphors in the examples is high.

Claims

1. The composition includes at least one Group 2 element selected from the group consisting of Mg, Ca, Sr, and Ba, as well as Eu, Si, Al, and N. In the above composition, the ratio of the total molar content of the Group 2 elements and Eu to the molar content of Al is 0.8 or more and 1.1 or less, the ratio of the molar content of Eu is 0.002 or more and 0.08 or less, the ratio of the molar content of Si is 0.8 or more and 1.2 or less, and the ratio of the total molar content of Si and Al is 1.8 or more and 2.2 or less. A nitride phosphor having an average aspect ratio (ratio of minor axis to major axis) of 0.72 or more and 0.77 or less, and an average circularity of 0.82 or more and 0.92 or less.

2. The nitride phosphor according to claim 1, wherein the volume-average particle size is 20 μm or more and 40 μm or less.

3. The nitride phosphor according to claim 1, wherein the ratio of the average particle size obtained by the air permeation method to the volume average particle size is 0.75 or more and 0.92 or less.

4. The nitride phosphor according to claim 1, wherein the logarithmic standard deviation of the particle size distribution based on volume of particle size is 0.25 or more and less than 0.

38.

5. The nitride phosphor according to claim 1, having a composition represented by the following formula (I). M a ｓ Sr ｔ Eu ｕ Yes ｖ Al ｗ N ｘ (I) (In formula (I), M ａ (Is a group 2 element that includes at least one element selected from the group consisting of Mg, Ca, and Ba, where s, t, u, v, w, and x satisfy the following conditions: 0 ≤ s < 1, 0 ≤ t < 1, 0.002 ≤ u ≤ 0.08, 0.8 ≤ s + t + u ≤ 1.1, 0.8 ≤ v ≤ 1.2, 0.8 ≤ w ≤ 1.2, 1.8 ≤ v + w ≤ 2.2, and 2.5 ≤ x ≤ 3.2.)

6. The nitride phosphor according to claim 5, wherein s, t, and u satisfy 0.94 ≤ s + t + u ≤ 1.10 in formula (I).

7. A light-emitting device comprising a fluorescent member containing a nitride phosphor according to any one of claims 1 to 6, and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm.

8. The light-emitting device according to claim 7, further comprising at least one selected from the group consisting of phosphors having a composition represented by any of the following formulas, for the fluorescent member. (Y,Gd,Tb,Lu) ３ (A-,1) ５ O １２ :Ce (--a) (Ca,Sr,Ba) ２ SiO ４ :Eu (IIb) Yes ６－ｐ Al ｐ OpN ８－ｐ :Eu(0<p≦4.2) (IIc) (Ca, Sr) ８ Yes ４ O １６ (F, Cl, Br) ２ :Eu (II$) (La,Y,Gd,Lu) ３ Yes ６ N １１ :Ce (IIe) (1,Sr,BL) ２ Yes ５ N ８ :Eu (IIg) (Ca,Sr,Ba)LiAl ３ N ４ :Eu (IIh) (Ca,Sr,Ba) １０ (2O ４ ) ６ (F,&-,Br) ２ :Eu (---)

9. The light-emitting device according to claim 7, further comprising at least one selected from the group consisting of phosphors having a composition represented by any of the following formulas, for the fluorescent member. A １ ｃ [M １ １－ｂ Mn ｂ F ｄ ] (II / ) (In formula (IIj), A １ It includes at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. １ It includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 and Group 14 elements. b satisfies 0 < b < 0.2, and c is [M １ １－ｂ Mn ｂ F ｄ (This is the absolute value of the ion's charge, where d satisfies 5 < d < 7.) A ２ ｆ [M ２ １－ｅ Mn ｅ F ｇ ] (-Ik) (In formula (IIk), A ２ It includes at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. ２ It includes at least Si and Al, and may further include at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. e satisfies 0 < e < 0.2, and f is [M ２ １－ｅ Mn ｅ F ｇ (This is the absolute value of the ion's charge, where g satisfies 5 < g < 7.)

10. The light-emitting device according to claim 8, further comprising at least one selected from the group consisting of phosphors having a composition represented by any of the following formulas, for the fluorescent member. A １ ｃ [M １ １－ｂ Mn ｂ F ｄ ] (II / ) (In formula (IIj), A １ It includes at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. １ It includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 and Group 14 elements. b satisfies 0 < b < 0.2, and c is [M １ １－ｂ Mn ｂ F ｄ (This is the absolute value of the ion's charge, where d satisfies 5 < d < 7.) A ２ ｆ [M ２ １－ｅ Mn ｅ F ｇ ] (-Ik) (In formula (IIk), A ２ It includes at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. ２ It includes at least Si and Al, and may further include at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. e satisfies 0 < e < 0.2, and f is [M ２ １－ｅ Mn ｅ F ｇ (This is the absolute value of the ion's charge, where g satisfies 5 < g < 7.)

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