Nitride phosphor and light-emitting device

Abstract

Provided is a nitride phosphor with which it is possible to obtain a higher luminous flux when constituting a light-emitting device. The nitride phosphor contains, in a composition, at least one group 2 element selected from the group consisting of Mg, Ca, Sr and Ba, Eu, Si, Al and N. The molar content of the Al in the composition is less than or equal to the molar content of the Sr in the composition, and the molar content of the N in the composition is less than or equal to the molar content of the Eu. The ratio of the total molar content of the group 2 element to the total molar content of Eu is 0.8 to 1.1, the ratio of the molar content of Eu is 0.002 to 0.08, the ratio of the molar content of Si is 0.8 to 1.2, and the ratio of the total molar content of Si and Al is 1.8 to 2.2. The nitride phosphor has an average aspect ratio, which is the ratio of the minor axis to the major axis, of from 0.72 to 0.77 (inclusive), and an average circularity of from 0.82 to 0.92 (inclusive).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a nitride phosphor and a light emitting device. BACKGROUND

[0002] A light emitting device in which a light emitting diode (hereinafter referred to as "LED") is combined with a phosphor is being applied to a lighting device, a backlight of a liquid crystal display device, and the like. As the phosphor used in the light emitting device, a nitride phosphor containing nitrogen in the composition can be cited, and as an example thereof, a phosphor in which CaAlSiN3 is a host crystal doped with Eu is known. 2+ An activated red phosphor (hereinafter, also referred to as "CASN phosphor") and a (Sr,Ca)AlSiN3:Eu (hereinafter, also referred to as "SCASN phosphor") in which a part of Ca of the CASN phosphor is substituted with Sr. The CASN phosphor and the SCASN phosphor have a peak wavelength of luminescence in a wide range of 600 nm to 670 nm depending on the composition thereof.

[0003] Regarding the nitride phosphor, Patent Literature 1 describes a phosphor powder in which the average circularity and the standard deviation of the circularity are within a given range.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2023 / 037727 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] An object of one embodiment of the present disclosure is to provide a nitride phosphor that can achieve a higher luminous flux when used in a light emitting device, and a light emitting device including the nitride phosphor.

[0009] METHOD FOR SOLVING THE PROBLEM

[0010] A first embodiment is a nitride phosphor including, in the composition, a Group 2 element including at least one selected from Mg, Ca, Sr, and Ba, Eu, Si, Al, and N. In the nitride phosphor, the total molar content ratio of the Group 2 element and Eu is higher than or equal to 0.8 and lower than or equal to 1.1, the molar content ratio of Eu is higher than or equal to 0.002 and lower than or equal to 0.08, the molar content ratio of Si is higher than or equal to 0.8 and lower than or equal to 1.2, and the total molar content ratio of Si and Al is higher than or equal to 1.8 and lower than or equal to 2.2, with respect to the molar content of Al in the composition. Further, the average value of the aspect ratio, which is the ratio of the short diameter to the long diameter, of the nitride phosphor is higher than or equal to 0.72 and lower than or equal to 0.77, and the average circularity is higher than or equal to 0.82 and lower than or equal to 0.92.

[0011] The second embodiment is a light-emitting device comprising a fluorescent component including a nitride phosphor of the first embodiment, and a light-emitting element having a light emission peak wavelength in the range of 365 nm or more and 500 nm or less.

[0012] The effects of the invention

[0013] According to one aspect of this disclosure, a nitride phosphor can be provided that can achieve higher luminous flux when used to construct a light-emitting device, and a light-emitting device incorporating the nitride phosphor can be provided. Attached Figure Description

[0014] Figure 1 This is an example of a scanning electron microscope (SEM) image of the nitride phosphor of Comparative Example 1.

[0015] Figure 2 This is an example of a SEM image showing the nitride phosphor of Example 1.

[0016] Figure 3 This is an example of a SEM image showing the nitride phosphor of Comparative Example 2.

[0017] Figure 4 This is an example of a SEM image showing the nitride phosphor of Example 2.

[0018] Figure 5 This is an example of a SEM image showing the nitride phosphor of Example 3.

[0019] Figure 6 This is an example of a SEM image showing the nitride phosphor of Example 4.

[0020] Figure 7 This is an example of a SEM image showing the nitride phosphor of Comparative Example 3.

[0021] Figure 8 This is an example of a SEM image showing the nitride phosphor of Example 5.

[0022] Figure 9 This is an example of a SEM image showing the nitride phosphor of Example 6.

[0023] Figure 10 This is an example of a SEM image showing the nitride phosphor of Example 7.

[0024] Figure 11 This is an example of a SEM image showing the nitride phosphor of Example 8.

[0025] Figure 12This is an example of a SEM image showing the nitride phosphor of Comparative Example 4.

[0026] Figure 13 This is an example of a SEM image showing the nitride phosphor of Example 9.

[0027] Figure 14 This is a schematic cross-sectional view showing an example of a light-emitting device. Detailed Implementation

[0028] In this specification, the term "process" is not limited to independent processes; it is included in any process that cannot be clearly distinguished from others, as long as its intended purpose is achieved. Furthermore, when multiple substances corresponding to each component are present in the composition, unless otherwise stated, the content of each component in the composition represents the total amount of those multiple substances present in the composition. Additionally, the upper and lower limits of the numerical ranges described in this specification 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 (,) indicate that the composition contains at least one of these multiple elements. Furthermore, in formulas representing the composition of phosphors, the part before the colon (:) indicates matrix crystallization, and the part after the colon (:) indicates the activating element. In this specification, the relationship between color names and chromaticity coordinates, and the relationship between the wavelength range of light and the color names of monochromatic light, are all based on JIS Z8110. The half-width at half maximum (FWHM) of a phosphor refers to the wavelength width (FWHM) of the emission spectrum in which the emission intensity reaches 50% of the maximum emission intensity. Hereinafter, embodiments of the present invention will be described in detail. However, the nitride phosphors and light-emitting devices exemplified in the embodiments shown below are used to embody the technical concept of the present invention, and the present invention is not limited to the nitride phosphors and light-emitting devices shown below.

[0029] Nitride phosphors

[0030] The nitride phosphor comprises, for example, at least one Group 2 element selected from Mg, Ca, Sr, and Ba, Eu, Si, Al, and N. In its composition, the molar ratio of the total molar content of the Group 2 element and Eu to the molar content of Al can be, for example, 0.8 or more and 1.1 or less; the molar ratio of Eu to Al can be, for example, 0.002 or more and 0.08 or less; the molar ratio of Si to Al can be, for example, 0.8 or more and 1.2 or less; and the molar ratio of the total molar content of Si and Al to the molar content of Al can be, for example, 1.8 or more and 2.2 or less. The average aspect ratio of the nitride phosphor, which is the ratio of the minor axis to the major axis, can be 0.72 or more and 0.77 or less. Furthermore, the average sphericity of the nitride phosphor can be 0.82 or more and 0.92 or less.

[0031] Nitride phosphors have a specific composition, and by shaping the particles to a specific range of aspect ratios and a specific range of average sphericity, high luminous flux can be achieved when constructing a light-emitting device. This can be attributed to, for example, the uniform dispersion and arrangement of the nitride phosphors in the resin constituting the wavelength conversion element of the light-emitting device, thereby reducing light loss caused by the reabsorption of light emitted by the light-emitting element and by light emitted by the nitride phosphor and other phosphors.

[0032] The nitride phosphor comprises, in its composition, at least one Group 2 element selected from Mg, Ca, Sr, and Ba. The Group 2 element 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 Group 2 elements in the composition of the nitride phosphor may be, for example, 0.8 or more, preferably 0.9 or more, and may be substantially only Ca and Sr. Here, "substantially" means that the unavoidable inclusion of Group 2 elements other than Ca and Sr is not excluded. 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.

[0033] In the composition of the nitride phosphor, the ratio of the total molar content of Group 2 elements and Eu to the molar content of Al is preferably 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 is preferably 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 is preferably 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 is preferably 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 X-ray fluorescence (XRF) analysis.

[0034] Nitride phosphors can have compositions such as those shown in formula (I) below.

[0035] M a s Sr t Eu u Si v Al w N x (I)

[0036] In formula (I), M a It is a Group 2 element selected from at least one of Mg, Ca, and Ba, preferably including at least Ca. s, t, u, v, w, and x can 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. Additionally, s, t, and u can satisfy 0.94 ≤ s + t + u ≤ 1.10.

[0037] The average aspect ratio (mean aspect ratio) of nitride phosphors, which is the ratio of the minor axis to the major axis, can be 0.72 or higher and 0.77 or lower, preferably 0.73 or higher, 0.76 or lower, or 0.75 or lower. The average aspect ratio of the nitride phosphor is the arithmetic mean of the minor axis to major axis ratios of arbitrarily selected 10 nitride phosphor particles. The selected nitride phosphor particles are chosen by excluding overlapping phosphor particles, phosphor particles whose overall shape is not captured, and the image recognition portions of obviously small phosphor particles from images taken using an optical microscope. The major axis is the maximum length of the line segment connecting two points on the outer edge of a nitride phosphor particle, and the minor axis is the maximum length of the line segment connecting the two intersection points of a straight line orthogonal to the major axis and the outer edge of the particle. Specifically, the aspect ratio of the nitride phosphor is determined using a particle image imaging and resolution device, Morphologi G3S (manufactured by MALVERN PANALYTICAL). In addition, 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.

[0038] The average roundness of the nitride phosphor can be 0.82 or higher and 0.92 or lower, preferably 0.85 or higher or 0.87 or higher, and 0.91 or lower or 0.90 or lower. The average roundness of the nitride phosphor is the arithmetic mean of the roundness of 10 randomly selected nitride phosphor particles. The selected nitride phosphor particles are selected by excluding overlapping phosphor particles, phosphor particles whose overall shape is not captured, and the image recognition portion of obviously small phosphor particles from images taken by observation with an optical microscope. In addition, the roundness of each nitride phosphor particle is calculated from the particle's projected area S and the particle's perimeter L by the following formula. Specifically, the roundness of the nitride phosphor particles is measured using a particle image imaging and resolving apparatus, Morphologi G3S (manufactured by MALVERN PANALYTICAL). It should be noted that the average roundness of nitride phosphors is evaluated by rounding the value to the third decimal place, resulting in a value with two decimal places.

[0039] Circularity = 4πS / L 2

[0040] The volume average particle size (Dm) of the nitride phosphor can be, for example, 20 μm or more and 40 μm or less. From the viewpoint of luminous efficiency, it is preferable to have a particle size of 23 μm or more, or 25 μm or more, or 36 μm or less. The larger the volume average particle size of the nitride phosphor, the higher the excitation light absorption rate and luminous efficiency tend to be. In this way, by applying a nitride phosphor with excellent optical properties to the light-emitting device described later, the luminous efficiency of the light-emitting device is further increased. In addition, the nitride phosphor preferably contains nitride phosphor particles with the above-mentioned volume average particle size value at a high frequency. That is, the particle size distribution is preferably distributed within a narrow range. By using a nitride phosphor with a small particle size distribution dispersion, a light-emitting device with further suppression of color spots and a better hue can be obtained. The logarithmic standard deviation (σlog) of the particle size distribution of the nitride phosphor based on the volume can be, for example, 0.25 or more and less than 0.38, preferably 0.37 or less, or 0.36 or less, or 0.26 or more.

[0041] It should be noted that the volume-average particle size of the nitride phosphor is determined from the volume-based particle size distribution curve obtained by measuring particle size distribution using laser diffraction scattering, and is taken as the particle size corresponding to 50% of the cumulative volume from the smallest diameter side. Specifically, the value is obtained by measuring the volume-based particle size distribution using a laser diffraction particle size distribution measuring device (e.g., MASTER SIZER3000 manufactured by MALVERN PANALYTICAL).

[0042] The average particle size (D) of the nitride phosphor obtained by air permeation can be, for example, 20 μm or more and 30 μm or less. From the viewpoint of luminescence efficiency, it is preferable to be 21 μm or more, or 22 μm or more, and less than 25 μm. The average particle size obtained by air permeation can be FSSS No. (Fisher Sub-Sieve Sizer's No.), for example, measured using a Fisher Sub-Sieve Sizer Model 95 manufactured by Fisher Scientific.

[0043] From the viewpoint of luminescence efficiency, the ratio (D / Dm) of the average particle size (D) of the nitride phosphor obtained by air permeation to the volume average particle size (Dm) can be, for example, 0.75 or more and 0.92 or less, preferably 0.76 or more or 0.77 or more, and 0.91 or less or 0.90 or less.

[0044] Nitride phosphors can have emission peak wavelengths in the range of, for example, 600 nm or higher and 675 nm or lower. Preferably, the emission peak wavelength of a nitride phosphor is 605 nm or higher, or 610 nm or higher, and more preferably 660 nm or lower, or 640 nm or lower. The half-width at half-maximum (WWHM) of the emission peak of a nitride phosphor can be, for example, 70 nm or higher and 78 nm or lower, preferably 76 nm or lower, or 74 nm or lower. If the WWHM of the emission peak is within the above range, there is a tendency to further increase the luminous flux of the light-emitting device.

[0045] Method for manufacturing nitride phosphors

[0046] A method for manufacturing a nitride phosphor may include heat-treating a mixture of raw materials containing a Group 2 element source, a europium source, a silicon source, and an aluminum source under a nitrogen-containing atmosphere at a temperature above 1800°C and below 2100°C to obtain a heat-treated product. The heat-treated product may contain a nitride phosphor, and the manufactured nitride phosphor may be the aforementioned nitride phosphor.

[0047] The group 2 element source contained in the raw material mixture is selected from at least one of Mg, Ca, Sr and Ba, and may contain at least one of Ca and Sr, and may contain at least Ca.

[0048] Examples of Group 2 element sources include: metal compounds containing Group 2 elements, elemental metals containing 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. Additionally, Group 2 element sources may also include Li, Na, K, B, and Al.

[0049] The Group 2 element source may contain at least a metal compound containing a Group 2 element. This 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 amide compounds and imide compounds containing a Group 2 element. By including a Group 2 element hydride in the Group 2 element source, a nitride phosphor with a fewer defective crystalline structure and larger particle size due to promoted crystal growth can be obtained. Furthermore, regarding the Group 2 element hydride, during heat treatment of the raw material mixture, the hydrogen contained in the hydride readily reacts with oxygen in the heat treatment atmosphere to form moisture and is released outside the reaction system. Therefore, oxygen and the like are less likely to be incorporated into the composition of the obtained nitride phosphor, resulting in a nitride phosphor with low content of elements other than the target composition, such as oxygen, that may cause a decrease in luminescence properties.

[0050] Amide compounds and imide compounds containing Group 2 elements (hereinafter also referred to as amide compounds and imide compounds containing Group 2 elements) are compounds in which the mass ratio of nitrogen per molecule is greater than that of nitrides containing Group 2 elements. As a source of Group 2 elements, by using at least one of amide compounds and imide compounds containing Group 2 elements, nitrogen can be supplied sufficiently in a manner close to the theoretical composition while supplying Group 2 elements, resulting in nitride phosphors with fewer defects in the crystalline structure and larger particle size due to promoted crystal growth.

[0051] Hydrides of Group 2 elements, specifically, include MgH2, CaH2, SrH2, BaH2, (Sr,Ca)H2, (Sr,Ca,Eu)H2, etc., and may contain at least one selected from them. Amide and imide compounds of Group 2 elements, specifically, 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 them.

[0052] The content of the hydride of the Group 2 element in the Group 2 element source relative to the total mass of the hydrides of the Group 2 element, the amide compounds of the Group 2 element, and the imide compounds can be, for example, in the range of 20% by mass or more and 80% by mass or less, preferably in the range of 25% by mass or more and 75% by mass or less. If the hydride content is within the above range, the Group 2 element and nitrogen element can be sufficiently supplied as elements constituting the crystal structure, and a nitride phosphor with excellent luminescence intensity, characterized by a crystal structure with suppressed defects and a larger grain size due to promoted crystal growth, can be obtained.

[0053] Hydrides, amides, and imides containing Group 2 elements can be compounds obtained through transfer or the like, or manufactured compounds. Hydrides can be manufactured by heat-treating, for example, a Group 2 metal element in an inactive atmosphere containing hydrogen. Amide and imide compounds can be manufactured by heat-treating a Group 2 metal element in an atmosphere containing nitrogen and hydrogen. From the viewpoint of reducing impurities in the resulting nitride phosphor, the purity of the hydrides, amides, and imides containing Group 2 elements can 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.

[0054] The Group 2 element source may also include compounds containing Group 2 elements other than hydrides, amides, and imides. Examples of other compounds containing Group 2 elements include oxides, hydroxides, nitrides, oxynitrides, and chlorides, and at least nitrides may be included. The content of compounds other than hydrides, amides, and imides 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.

[0055] Examples of europium sources contained in raw material mixtures include europium compounds, elemental europium, and europium alloys. Examples of europium compounds include oxides, hydroxides, nitrides, nitrides, fluorides, and chlorides containing europium. Specifically, examples of europium compounds include europium oxide (Eu₂O₃), europium nitride (EuN), and europium fluoride (EuF₃), and at least one selected from these may be included. Europium nitride (EuN) consists only of the elements that make up the target phosphor, thus more effectively suppressing the incorporation of impurities. Furthermore, europium oxide (Eu₂O₃) and europium fluoride (EuF₃) sometimes function as fluxes and are preferred. A single europium compound may be used, or two or more may be used in combination.

[0056] Europium compounds can be obtained and used through transfer or by manufacturing the desired europium compound. For example, europium nitride can be obtained by nitriding europium as a raw material by pulverizing europium in an inert gas atmosphere and then heat-treating the resulting powder in a nitrogen atmosphere or an ammonia atmosphere. The average particle size of the pulverized europium can be, for example, 0.1 μm or more and 10 μm or less. Furthermore, the heat treatment temperature can be, for example, 600°C or more and 1200°C or less, and the heat treatment time can be, for example, 1 hour or more and 20 hours or less. The resulting europium nitride can be, for example, pulverized in an inert gas atmosphere.

[0057] The raw material mixture can also be a mixture in which at least a portion of the europium source is replaced by metallic compounds, elemental metals, alloys, etc., 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.

[0058] The purity of the europium source (e.g., a europium compound) can be, for example, 95% by mass or more, preferably 99.5% by mass or more. By setting the purity to a given value or higher, the adverse effects caused by the presence of impurities can be reduced, thereby further improving the luminescence intensity of the nitride phosphor.

[0059] Examples of silicon sources contained in the raw material mixture include silicon compounds, elemental silicon, and silicon alloys. Examples of silicon compounds include oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides containing silicon. Specifically, examples of silicon compounds include silicon oxide, silicon nitride, silicon oxynitride, and silicates; preferably, at least one selected from these is used, and more preferably, silicon nitride. Since silicon nitride is composed only of the elements that make up the target phosphor, it can more effectively suppress the incorporation of impurities. For example, compared to silicon compounds containing oxygen and hydrogen, silicon nitride can reduce the influence of these elements, and compared to elemental metals, a nitriding reaction is not required. A single silicon compound can be used, or two or more can be used in combination.

[0060] Silicon compounds can be obtained through transfer or other means, or they can be manufactured and used to produce the desired silicon compound. For example, silicon nitride can be obtained by pulverizing silicon as a raw material in an inert gas atmosphere, and then heat-treating the resulting powder in a nitrogen atmosphere to nitride it. The heat treatment temperature can be, for example, above 800°C and below 2000°C, and the heat treatment time can be, for example, above 1 hour and below 20 hours. The obtained silicon nitride can be pulverized, for example, in an inert gas atmosphere.

[0061] The raw material mixture can be a mixture of metal compounds, metallic elements, alloys, etc., in which a portion of the silicon source is replaced by elements from Group 4 or Group 14 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.

[0062] The purity of the silicon source (e.g., a silicon compound) can be, for example, 95% by mass or more, preferably 99% by mass or more. By setting the purity to a given value or higher, the influence of impurities can be reduced, thereby further improving the luminescence intensity of the nitride phosphor.

[0063] Examples of aluminum sources contained in the raw material mixture include aluminum compounds, elemental aluminum, and aluminum alloys. Examples of aluminum compounds include oxides, hydroxides, nitrides, nitrogen oxides, fluorides, and chlorides containing aluminum. Specifically, examples of aluminum compounds include aluminum nitride (AlN), aluminum oxide (Al₂O₃), and aluminum hydroxide (Al(OH)₃), with at least one selected from these preferred, and aluminum nitride being more preferred. Since aluminum nitride is composed only of the elements that make up the target phosphor, it can more effectively suppress the incorporation of impurities. For example, compared to aluminum compounds containing oxygen and hydrogen, aluminum nitride can reduce the influence of these elements, and compared to elemental aluminum, a nitriding reaction is not required. One aluminum compound can be used alone, or two or more can be used in combination.

[0064] Aluminum compounds can be obtained and used through transfer or by manufacturing desired aluminum compounds. For example, aluminum nitride can be manufactured by methods such as direct nitriding of aluminum.

[0065] The raw material mixture can be a mixture of metal compounds, metallic elements, alloys, etc., in which at least a portion of the aluminum source is replaced by Group 13 elements such as gallium (Ga), indium (In), Group 5 elements such as vanadium (V), Group 6 elements such as chromium (Cr), or Group 9 elements such as cobalt (Co). Examples of metal compounds include oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides.

[0066] The purity of the aluminum source (e.g., an aluminum compound) can be, for example, 95% by mass or more, preferably 99% by mass or more. By setting the purity to a given value or higher, the influence of impurities can be reduced, thereby further improving the luminescence intensity of the phosphor.

[0067] The feedstock mixture may further contain at least one of a metal fluoride. By further containing at least one of a metal fluoride, the feedstock mixture tends to produce nitride phosphors exhibiting higher luminescence intensity.

[0068] The metal fluoride preferably includes at least one selected from 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.

[0069] The group 2 element in the metal fluoride may include at least one selected from Mg, Ca, Sr, and Ba, preferably at least one of Sr and Ca, and more preferably at least Ca. When the feed mixture contains 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, a portion of the group 2 element source may be replaced by a metal fluoride containing a group 2 element.

[0070] 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 the Group 2 element to the molar amount of the Group 2 element source can be, for example, 0.05 or more and less than 1, preferably 0.08 or more or 0.1 or more, and even more preferably 0.8 or less, 0.6 or less or 0.4 or less.

[0071] The rare earth element in the metal fluoride may include at least one selected from Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, preferably Eu. When the feed mixture contains a metal fluoride containing a rare earth element, the metal fluoride containing the rare earth element may be part of a europium source. That is, a portion of the europium source may be replaced by a metal fluoride containing a rare earth element.

[0072] When a portion of the europium source is replaced by a metal fluoride containing rare earth elements, the ratio of the number of moles of the metal fluoride containing rare earth elements to the molar amount of the europium source can be, for example, 0.05 or more and less than 1, preferably 0.08 or more or 0.1 or more, and even more preferably 0.8 or less, 0.6 or less or 0.4 or less.

[0073] The group 4 or group 14 element in the metal fluoride may include at least one element selected from Ge, Sn, Ti, Zr, and Hf. When the feedstock 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, a portion of the silicon source may be replaced by a metal fluoride containing a group 4 or group 14 element.

[0074] 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 the Group 4 or Group 14 element to the molar amount of the silicon source can be, for example, 0.05 or more and less than 1, preferably 0.08 or more or 0.1 or more, and even more preferably 0.8 or less, 0.6 or less or 0.4 or less.

[0075] The group 13 element in the metal fluoride may include at least one selected from Al, Ga, and In, preferably Al. When the feed mixture contains 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, a portion of the aluminum source may be replaced by a metal fluoride containing a group 13 element.

[0076] When a portion of the aluminum source is replaced by a metal fluoride containing a Group 13 element, the ratio of the number of moles of the metal fluoride containing the Group 13 element to the molar amount of the aluminum source can be, for example, 0.05 or more and less than 1, preferably 0.08 or more or 0.1 or more, and even more preferably 0.8 or less, 0.6 or less or 0.4 or less.

[0077] The content of metal fluoride in the raw material mixture is such that the molar ratio of fluorine atoms to aluminum is, for example, 0.01 or more and 0.3 or less. Preferably, the molar ratio is 0.01 or more and less than 0.3, more preferably 0.015 or more and 0.2 or less, even more preferably 0.02 or more and 0.15 or less, and even more preferably 0.025 or more and 0.1 or less. By setting the molar ratio to the lower limit or above, the effect as a flux can be sufficiently obtained. When a certain amount of flux is contained, if the effect of the flux is saturated, the effect cannot be improved even if more than that amount is contained. Therefore, by setting it to the upper limit or below, the effect of the flux can be obtained without containing more than the desired amount of flux.

[0078] The purity of the metal fluoride can be, for example, 95% by weight or more, preferably 99% by weight or more. By setting the purity to a given value or higher, the influence of impurities can be reduced, thereby further improving the luminescence intensity of the phosphor. Furthermore, metal fluorides containing Group 2 sources can further contain Li, Na, K, B, Al, etc. Metal fluorides can be obtained and used through transfer or other means, or they can be manufactured to produce the desired metal fluoride.

[0079] When the raw material mixture contains metal fluorides, it may further contain fluxes such as halides in addition to metal fluorides. Examples of halides include chlorides and fluorides of rare earth elements and alkali metals. When the raw material mixture contains fluxes, their content relative to metal fluorides is, for example, 20% by mass or less, preferably 10% by mass or less, and more preferably 1% by mass or less.

[0080] The raw material mixture may further include nitride phosphors prepared separately as needed. When the raw material mixture includes nitride phosphors, their content in the total amount of the raw material mixture may be, for example, more than 1% by mass and less than 50% by mass.

[0081] 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 given molar ratio. Regarding the mixing ratio of each component in the raw material mixture, for example, the ratio of the total molar content of Group 2 elements and europium to the molar content of aluminum can be 0.8 or more and 1.1 or less, preferably 0.9 or more and 1.05 or less. Furthermore, the ratio of the molar content of europium to the molar content of aluminum can 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 can 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 can be 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less.

[0082] Regarding the mixing ratio of the components in the raw material mixture, for example, s, t, u, v, w and x in the following formula (Ia) can be selected in a manner that satisfies the following conditions specified in formula (Ia).

[0083] M a s Sr t Eu u Si v Al w N x (Ia)

[0084] In equation (Ia), M a It is a Group 2 element containing at least one element selected from Mg, Ca, and Ba. s, t, u, v, w, and x 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. Additionally, s, t, and u satisfy 0.94 ≤ s + t + u ≤ 1.10.

[0085] The raw material mixture can be obtained by weighing each component of the raw material mixture in a desired proportion, and then mixing the components using a mixing method such as a ball mill, a mixing method using a Henschel mixer, a V-type mixer, or a mixing method using a mortar and pestle. Mixing can be carried out by dry mixing or by adding solvents to carry out wet mixing.

[0086] The desired nitride phosphor can be obtained by heat-treating the resulting raw material mixture. The heat-treating temperature can be, for example, in the range of 1200°C or higher and 2200°C or lower, preferably 1500°C or higher, 1800°C or higher, 1850°C or higher, or 1900°C or higher, and can 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 given value, europium readily enters the crystalline structure, resulting in phosphors with promoted crystal growth, larger particle size, and excellent luminescence intensity. Furthermore, if the heat-treating temperature of the raw material mixture is below a given temperature, the decomposition of the formed crystalline structure is suppressed, and a nitride phosphor with a crystalline structure having fewer defects can be obtained. The heat treatment of the raw material mixture can be performed, for example, in a gas-pressurized electric furnace.

[0087] The heat treatment of the raw material mixture can be carried out at a single temperature or in a multi-stage manner involving two or more heat treatment temperatures. In the case of multi-stage heat treatment, for example, a first stage heat treatment can be performed at a temperature of 1200°C or higher and 1600°C or lower, preferably 1300°C or higher and 1500°C or lower, followed by a gradual increase in temperature to a second stage heat treatment at 1800°C or higher and 2100°C or lower, preferably 1850°C or higher and 2050°C or lower. Furthermore, the multi-stage heat treatment can include: for example, performing a first heat treatment on the raw material mixture at a temperature of 1200°C or higher and 1600°C or lower, preferably 1300°C or higher and 1500°C to obtain a first heat-treated product; and then, cooling the first heat-treated product to perform a second heat treatment at a temperature of 1800°C or higher and 2100°C or lower, preferably 1850°C or higher and 2050°C or lower to obtain a second heat-treated product. Further processing may include obtaining a pulverized product by crushing or pulverizing the first heat-treated material. Through multi-stage heat treatment, there is a tendency to obtain nitride phosphors that exhibit higher luminescence intensity.

[0088] In the heat treatment of the raw material mixture, for example, heat treatment is performed by heating from room temperature to a given temperature. The heating time is, for example, more than 1 hour and less than 48 hours, preferably more than 2 hours and less than 24 hours, and more preferably more than 3 hours and less than 20 hours. If the heating time is above the above lower limit, there is a tendency for sufficient particle growth of the nitride phosphor, and there is a tendency for europium to easily enter the crystal of the nitride phosphor.

[0089] In the heat treatment of the raw material mixture, a holding time at a given temperature can be set. 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 above the aforementioned lower limit, more uniform particle growth can be further promoted. Furthermore, by setting the holding time below the aforementioned upper limit, the decomposition of the phosphor can be further suppressed.

[0090] The time for cooling from a given 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. It should be noted that the holding time at a temperature appropriately selected between the given temperature and room temperature can be set. This holding time is adjusted, for example, in a way that the luminescence intensity of the nitride phosphor is further improved. The holding time at the given temperature during cooling can be, for example, 0.1 hours or more and 20 hours or less, preferably 1 hour or more and 10 hours or less. Furthermore, 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.

[0091] The atmosphere for heat treatment of the raw material mixture can be, for example, an atmosphere containing nitrogen, preferably a substantially nitrogen atmosphere. By setting the atmosphere to contain nitrogen, the silicon contained in the raw material can be nitrided. In addition, the decomposition of the raw material and the phosphor, which are nitrides, can be suppressed. When the atmosphere for heat treatment of the raw material mixture contains nitrogen, in addition to nitrogen, other gases such as hydrogen, argon, carbon dioxide, carbon monoxide, oxygen, and ammonia can also be included. Furthermore, the nitrogen content in the atmosphere for heat treatment of the raw material mixture can be, for example, 90% by volume or more, preferably 95% by volume or more. By setting the content of gases containing elements other than nitrogen to a given value or less, there is a tendency to suppress the decrease in phosphor luminescence intensity caused by the formation of impurities by these gas components.

[0092] The pressure for heat treatment of the raw material mixture can be set, for example, from atmospheric pressure to 200 MPa. From the viewpoint of suppressing the decomposition of the generated nitride phosphor, a high pressure is preferred. As a gauge pressure, it can be, for example, in the range of 0.1 MPa or more and 200 MPa or less, and preferably in the range of 0.6 MPa or more and 1.2 MPa or less, which is less of a limitation for industrial equipment.

[0093] The heat treatment of the raw material mixture can be performed by filling the raw material mixture into a crucible or boat made of a material selected from carbon materials such as graphite, boron nitride (BN), alumina (Al2O3), molybdenum (Mo), and tungsten (W). From the viewpoint of suppressing the introduction of impurities into the resulting nitride phosphor, it is preferable to use a crucible or boat made of boron nitride or tungsten in the heat treatment of the raw material mixture.

[0094] In one method, the heat treatment of the raw material mixture can be carried out in a sealed container made of tungsten. This allows for the efficient production of nitride phosphors exhibiting higher luminescence intensity. The sealed container for heat treatment of the raw material mixture can be substantially made of tungsten. Here, "substantially" means without excluding unavoidable impurities.

[0095] Here, a sealed container refers to a container that, under normal handling, transportation, or storage conditions, can prevent the introduction of solid foreign matter (e.g., Japanese Pharmacopoeia General Chapter 37). A sealed container, for example, consists of a container body with an opening and a lid that seals the opening of the container body, preventing the entry or exit of solids under heat treatment conditions. Furthermore, in a sealed container, it is sufficient to suppress the entry or exit of gases under heat treatment conditions, rather than completely preventing gas entry or exit. The shape of the container body of the sealed container, for example, has a bottom and a wall surrounding the bottom, and the upper part opposite the bottom can be an opening. The shape of the container body can be, for example, cylindrical, polygonal, square, etc. For a tungsten-made sealed container, at least the portion in contact with the raw material mixture should be substantially formed of tungsten; preferably, the entire sealed container should be substantially formed of tungsten.

[0096] The amount of raw material mixture contained in the sealed container can be, for example, 60% or more and 100% or less by volume, and preferably 75% or more and 99% or less by volume, relative to the capacity of the sealed container.

[0097] Granulation can be achieved by pulverizing and classifying the heat-treated material obtained from a heat-treated mixture. This granulation process yields phosphor particles with the desired particle size. Specifically, the heat-treated material is coarsely pulverized (also known as crushing) and then pulverized to a given particle size using a conventional pulverizer such as a ball mill, jet mill, or vibratory mill. If differences in particle size exist after pulverization, classification can be performed to obtain nitride phosphors of the desired particle size. To remove thermal decomposition products adhering to the surface of the sintered material, the sintered material can be cleaned by contacting it with deionized water, an acidic solution, or an alkaline solution before or after classification.

[0098] One method for manufacturing a nitride phosphor may include: subjecting a mixture of raw materials containing a Group 2 element source, a europium source, a silicon source, and an aluminum source to a first heat treatment in a tungsten-made sealed container at a temperature above 1200°C and below 1600°C to obtain a first heat-treated product; and subjecting the first heat-treated product to a second heat treatment in a tungsten-made sealed container at a temperature above 1800°C and below 2100°C to obtain a second heat-treated product, wherein the Group 2 element source may include at least one selected from hydrides containing at least one Group 2 element, amide compounds containing a Group 2 element, and imide compounds.

[0099] Light-emitting device

[0100] One embodiment of the light-emitting device may include: a fluorescent component comprising the nitride phosphor described above, and a light-emitting element having a peak emission wavelength in the range of 365 nm to 500 nm. Based on Figure 14 The light-emitting device 100 will be described. The light-emitting device 100 is an example of a surface-mount type light-emitting device. The light-emitting device 100 includes a gallium nitride-based compound semiconductor light-emitting element 10 with a peak emission wavelength in the range of 380 nm or more and 470 nm or less, and a molded body 40 on which the light-emitting element 10 is mounted. The molded body 40 is integrally formed from a first lead 20 and a second lead 30 and a resin portion 42. The molded body 40 has a recess having a bottom surface and a side surface, 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, which are electrically connected to a wire 60 via the first lead 20 and the second lead 30, respectively. The light-emitting element 10 is covered by a fluorescent member 50. The fluorescent member 50, for example, contains a phosphor 70 that converts the wavelength of light emitted from the light-emitting element 10 and resin.

[0101] The emission peak wavelength of the light-emitting element 10 is preferably in the range of 380 nm or more and 470 nm or less, or 400 nm or more and 460 nm or less. By using the light-emitting element 10 with an emission peak wavelength in this range as a light source, a light-emitting device 100 that emits mixed light from the light-emitting element 10 and the fluorescence from the fluorescent component 50 can be constructed. Furthermore, since a portion of the light emitted by the light-emitting element 10 can be effectively utilized as part of the light emitted by the light-emitting device 100 to the outside, a light-emitting device 100 with high luminous efficiency can be obtained.

[0102] The half-width of the emission spectrum of the light-emitting element 10 can be set to, for example, 30 nm or less. As the light-emitting element, a semiconductor light-emitting element using a nitride-based semiconductor is preferably used, for example. By using a semiconductor light-emitting element as the excitation light source, a stable light-emitting device with high efficiency, high linearity of output relative to input, and strong resistance to mechanical shock can be obtained.

[0103] 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 besides the nitride phosphor. By including other phosphors, the fluorescent component can be configured as a light-emitting device that emits a mixture of light emitted by the light-emitting element, the nitride phosphor, and other phosphors.

[0104] Other phosphors include, for example, phosphors having the composition shown in any one of formulas (IIa) to (IIi) below, preferably including at least one phosphor having the composition selected from those formulas, and more preferably including at least one phosphor having the composition shown in formulas (IIa), (IIb), (IIc), (IId), (IIe), (IIg), (IIh), or (IIi). This is because by including these other phosphors, a light-emitting device with high color rendering and luminous efficiency can be obtained. The light-emitting device may include one other phosphor alone, or it may include two or more phosphors in combination.

[0105] (Y,Gd,Tb,Lu)3(Al,Ga)5O 12 :Ce (IIa)

[0106] (Ca,Sr,Ba)2SiO4:Eu (IIb)

[0107] Si 6-p Al p O p N 8-p Eu(0<p≤4.2) (IIc)

[0108] (Ca,Sr)8MgSi4O 16 (F,Cl,Br)2:Eu (IId)

[0109] (La,Y,Gd,Lu)3Si6N 11 :Ce (IIe)

[0110] (Ca,Sr,Ba)2Si5N8:Eu (IIg)

[0111] (Ca,Sr,Ba)LiAl3N4:Eu (IIh)

[0112] (Ca,Sr,Ba) 10 (PO4)6(F,Cl,Br)2:Eu (IIi)

[0113] Other examples of phosphors include, for instance, phosphors having the composition shown in any one of the following formulas (IIj) and (IIk), and preferably including at least one phosphor selected from those having the composition shown in these formulas. Including these other phosphors is more preferable from the viewpoint of obtaining a light-emitting device with high color rendering and luminous efficiency.

[0114] A 1 c [M 1 1-b Mn b F d (IIj)

[0115] A 2 f [M 2 1-e Mn e F g (IIk)

[0116] In equation (IIj), A 1 It contains at least one element selected from Li, Na, K, Rb, and Cs. M 1 It contains at least one element selected from Si and Ge, and may further contain at least one element selected from Group 4 and Group 14. b satisfies 0 < b < 0.2, and c is [M... 1 1-b Mn b F d The absolute value of the charge of an ion, d, satisfies 5 < d < 7.

[0117] In equation (IIk), A 2 It contains at least one element selected from Li, Na, K, Rb, and Cs. M 2 It must contain at least Si and Al, and may further contain at least one element from Group 4, Group 13, and Group 14. e satisfies 0 < e < 0.2, and f is [M 2 1-e Mn e F g The absolute value of the charge of an ion, g, satisfies 5 < g < 7.

[0118] The average particle size of the other phosphors can be, for example, 2 μm or more and 35 μm or less, preferably 5 μm or more and 30 μm or less. If the average particle size of the other phosphors is above or below the aforementioned lower limit, the absorption rate of light from the excitation source can be increased, resulting in luminescence with the desired chromaticity at a higher luminescence intensity. Furthermore, if the average particle size of the other phosphors is below or below the aforementioned upper limit, the operability of the manufacturing process of the light-emitting device can be improved when the fluorescent component of the light-emitting device contains other phosphors.

[0119] In addition to the nitride phosphor, the fluorescent component 50 may also contain at least one type of resin. Examples of resins include epoxy resin and silicone resin.

[0120] In addition to the nitride phosphor, the fluorescent component 50 may further contain other components as needed. Examples of other components include fillers such as silica, barium titanate, titanium dioxide, and alumina, as well as light stabilizers and colorants. When the fluorescent component contains other components, for example, when fillers are included, the content may be set to 0.01 to 20 parts by weight relative to 100 parts by weight of the resin.

[0121] The invention disclosed herein may include, for example, the following methods.

[0122] [1] A nitride phosphor comprising:

[0123] It contains at least one Group 2 element selected from Mg, Ca, Sr and Ba.

[0124] Eu、

[0125] Si、

[0126] Al, and

[0127] N,

[0128] Wherein, relative to the molar content of Al in the composition, the ratio of the total molar content of the Group 2 elements to Eu 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.

[0129] The average length-to-diameter ratio, which is the ratio of the minor diameter to the major diameter, is 0.72 or higher and 0.77 or lower, and the average roundness is 0.82 or higher and 0.92 or lower.

[0130] [2] The nitride phosphor according to [1] has a volume average particle size of 20 μm or more and 40 μm or less.

[0131] [3] The nitride phosphor according to [1] or [2], wherein,

[0132] The ratio of the average particle size to the volume average particle size obtained by air permeation is greater than 0.75 and less than 0.92.

[0133] [4] The nitride phosphor according to any one of [1] to [3], wherein,

[0134] The logarithmic standard deviation of the volume-based particle size distribution is greater than 0.25 and less than 0.38.

[0135] [5] The nitride phosphor according to any one of [1] to [4] has the composition shown in the following formula (I).

[0136] M a s Sr t Eu u Si v Al w N x (I)

[0137] In formula (I), M a It is a group 2 element containing at least one of Mg, Ca and Ba, and s, t, u, v, w and x 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.

[0138] [6] According to the nitride phosphor described in [5], wherein,

[0139] In equation (I), s, t, and u satisfy 0.94≤s+t+u≤1.10.

[0140] [7] A light-emitting device comprising:

[0141] Fluorescent components comprising any one of the nitride phosphors described in [1] to [6], and

[0142] Light-emitting elements having a peak emission wavelength in the range of 365nm to 500nm.

[0143] [8] According to the light-emitting device described in [7], wherein,

[0144] The fluorescent component further comprises at least one phosphor selected from those having a composition shown in any one of the following formulas.

[0145] (Y,Gd,Tb,Lu)3(Al,Ga)5O 12 :Ce (IIa)

[0146] (Ca,Sr,Ba)2SiO4:Eu (IIb)

[0147] Si 6-p Al p O p N 8-p Eu(0<p≤4.2) (IIc)

[0148] (Ca,Sr)8MgSi4O 16 (F,Cl,Br)2:Eu (IId)

[0149] (La,Y,Gd,Lu)3Si6N 11 :Ce (IIe)

[0150] (Ca,Sr,Ba)2Si5N8:Eu (IIg)

[0151] (Ca,Sr,Ba)LiAl3N4:Eu (IIh)

[0152] (Ca,Sr,Ba) 10 (PO4)6(F,Cl,Br)2:Eu (IIi)

[0153] [9] The light-emitting device according to [7] or [8], wherein,

[0154] The fluorescent component further comprises at least one phosphor selected from those having a composition shown in any one of the following formulas.

[0155] A 1 c [M 1 1-b Mn b F d (IIj)

[0156] In equation (IIj), A 1 Includes at least one element selected from Li, Na, K, Rb, and Cs, M 1 It contains at least one of Si and Ge, and optionally further contains or excludes at least one element selected from Group 4 and Group 14. b satisfies 0 < b < 0.2, and c is [M 1 1-b Mn b F d The absolute value of the charge of an ion, d, satisfies 5 < d < 7.

[0157] A 2 f [M 2 1-e Mn e F g (IIk)

[0158] In equation (IIk), A 2 It contains at least one element selected from Li, Na, K, Rb, and Cs. M 2It contains at least Si and Al, and optionally further contains or excludes at least one element selected from Group 4, Group 13, and Group 14. e satisfies 0 < e < 0.2, and f is [M 2 1-e Mn e F g The absolute value of the charge of an ion, g, satisfies 5 < g < 7.

[0159] Example

[0160] The present invention will now be described in more detail based on embodiments, but the present invention is not limited to these embodiments.

[0161] Reference Example 1: Preparation of Strontium Hydrogen (SrH2)

[0162] Metallic Sr was placed in an alumina boat in a glove box under an inert (Ar) atmosphere. The boat was then heat-treated in a tube furnace at 600°C for 12 hours under an argon atmosphere containing hydrogen (Ar flow rate: 5 L / min, H2 flow rate: 2.5 L / min) to obtain a heat-treated product. The heat-treated product was then coarsely pulverized and mixed with other heat-treated materials. The coarsely pulverized product was then heat-treated again under an argon atmosphere containing hydrogen in the same manner as described above. This heat treatment and coarse pulverization were repeated four times. Subsequently, the powder was pulverized and classified using a mortar and pestle in a glove box under an inert (Ar) atmosphere to obtain the powder of Reference Example 1. The obtained powder was X-ray diffraction (XRD) spectra measured in an inert atmosphere using a sample-level multi-functional X-ray diffractometer (product name: Ultima IV, manufactured by Rigaku Co., Ltd., X-ray source: CuKα rays (λ=1.5418 Å), tube voltage 40 kV, tube current 40 mA). Based on the X-ray diffraction spectrum of the obtained powder, it was confirmed that the powder of Reference Example 1 was strontium hydride (SrH2).

[0163] Refer to Example 2: Preparation of Strontium Sources

[0164] Metallic Sr was placed in an alumina boat in a glove box under an inert (Ar) atmosphere. The boat was then heat-treated in a tube furnace at 300°C for 12 hours under a nitrogen atmosphere containing hydrogen (N2 flow rate: 21.5 L / min, H2 flow rate: 0.9 L / min) to obtain a heat-treated product. The obtained heat-treated product was then coarsely pulverized and mixed. The coarsely pulverized product was then heat-treated again under a nitrogen atmosphere containing hydrogen in the same manner as above. This heat treatment and coarse pulverization were repeated three times. Subsequently, the product was pulverized and classified using a mortar and pestle in a glove box under an inert (Ar) atmosphere to obtain the powder of Reference Example 2. The obtained powder was subjected to X-ray diffraction (XRD) spectra in an inactive atmosphere using a sample-level multifunctional X-ray diffractometer (manufactured by Rigaku Co., Ltd., X-ray source: CuKα rays (λ=1.5418Å), tube voltage 40kV, tube current 40mA, product name: UltimaIV). Based on the X-ray diffraction spectrum of the obtained powder, it was confirmed that the powder of Reference Example 2 was a mixture of strontium imide and strontium hydride (x(SrNH)+(1-x)(SrH2), x=1 / 4 corresponding; hereinafter, sometimes abbreviated as "Sr3N2").

[0165] Example 1

[0166] Using the powder (x(SrNH)+(1-x)(SrH2), x=1 / 4 corresponding to Sr3N2), calcium nitride (Ca3N2), calcium fluoride (CaF2), europium nitride (EuN), aluminum nitride (AlN), and silicon nitride (Si3N4) prepared in Reference Example 2 as raw materials, each compound was metered in a glove box under an inactive atmosphere as the addition ratio, such that the molar ratio of each element was Ca(Ca3N2):Ca(CaF2):Sr:Eu:Al:Si:F=0.021:0.009:0.965:0.005:1:1:0.009 and mixed to obtain a raw material mixture. The raw material mixture was filled into a tungsten crucible and sealed. Under a nitrogen atmosphere, the first stage of heat treatment was carried out at a pressure of 0.92 MPa, a heat treatment temperature of 1400 °C, and a holding time of 3 hours to obtain the precursor. The precursor was pulverized and homogenized in a glove box under an inactive atmosphere, then refilled into a tungsten crucible and sealed. A second stage of heat treatment was performed under a nitrogen atmosphere, a gauge pressure of 0.92 MPa, a heat treatment temperature of 1950°C, and a holding time of 15 hours. Subsequently, through pulverization, dispersion, and classification, the nitride phosphor powder of Example 1 was obtained.

[0167] Comparative Example 1

[0168] Ca3N2, CaF2, SrN x(x=2 / 3 corresponds to a mixture of Sr2N and SrN), AlN3, Si3N4, and EuN were used as raw materials. A raw material mixture was obtained with a molar ratio of Ca(Ca3N2):Ca(CaF2):Sr:Eu:Al:Si:F=0.009:0.021:0.965:0.005:1:1:0.042. Otherwise, the same operation as in Example 1 was performed to obtain the nitride phosphor powder of Comparative Example 1.

[0169] Examples 2-8

[0170] The raw material mixture was obtained by adding the components in the manner described in Table 1 with the molar ratio of each element in the raw material mixture. Otherwise, the same operation as in Example 1 was performed to obtain the nitride phosphor powders of Examples 2 to 8.

[0171] Comparative Examples 2-4

[0172] The raw material mixture was obtained by adding the components in the manner described in Table 1 with the molar ratio of each element in the raw material mixture. Otherwise, the same operation as in Comparative Example 1 was performed to obtain the nitride phosphor powders of Comparative Examples 2 to 4.

[0173] Example 9

[0174] Using the powder (SrH2) of Reference Example 1 instead of the powder of Reference Example 2 as the strontium source, the raw material mixture was obtained in such a way that the molar ratio of each element in the raw material mixture was the addition composition ratio recorded in Table 1. Otherwise, the same operation as in Example 1 was performed to obtain the nitride phosphor powder of Example 9.

[0175]

[0176] Compositional analysis

[0177] For the nitride phosphors of each embodiment and comparative example, the constituent elements of the nitride phosphors were analyzed using a scanning fluorescence X-ray analysis (XRF) apparatus (RIGAKU, product name: ZSX primusII), an ion chromatography (IC) apparatus (Thermo Scientific Dionex, product name: Dionex Integrion HPIC), and an oxygen / nitrogen / hydrogen analysis apparatus (HORIBA, product name: EMGA-930), and the molar ratios of each element were calculated. The molar ratio of Al in the composition was set to 1, and the molar ratios of each element were calculated. The results are shown in Table 1.

[0178] Average roundness

[0179] The average sphericity of the nitride phosphors obtained in each embodiment and comparative example was determined as follows. Excluding overlapping phosphor particles, phosphor particles whose overall shape was not captured, and the image recognition portion of obviously small phosphor particles, 10 particles were randomly selected from images taken by observation through an optical microscope, and image processing software (MALVERN PANALYTICAL) was used. The projected area (S(m²)) of each selected particle was measured by the company (MORPHOLOGIG3S). 2 The sphericity of each particle was calculated using the following formula, taking the circumference (L(m)) and the circumference (L(m)). The arithmetic mean of the calculated sphericity of each particle was then calculated and rounded to the third decimal place, which was taken as the average sphericity of the nitride phosphors obtained in each embodiment and comparative example. The results are shown in Table 2.

[0180] Circularity = 4πS / L 2

[0181] Average length-to-diameter ratio

[0182] The average aspect ratio of the nitride phosphors obtained in each embodiment and comparative example was determined as follows. Excluding overlapping phosphor particles, phosphor particles whose overall shape was not captured, and the image recognition portion of obviously small phosphor particles, 10 particles were randomly selected from images taken by observation through an optical microscope, and image processing software (MALVERN PANALYTICAL) was used. The major and minor axes of the selected particles were measured using a company (MORPHOLOGI G3S), and the ratio of the minor axis to the major axis (minor axis / major axis) was calculated as the aspect ratio of each particle. The arithmetic mean of the calculated aspect ratios of each particle was calculated, rounded to the third decimal place, and used as the average aspect ratio of the nitride phosphors obtained in each example and comparative example. The results are shown in Table 2.

[0183] Powder determination

[0184] For the nitride phosphors obtained in each example and comparative example, the average particle size was determined by measuring the specific surface area using the air permeation method (FSSS) and utilizing the air flow resistance. The average particle size determined by the air permeation method is also called the Fisher Sub-Sieve Sizer's Number. Specifically, using a Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific), at an environment of 25°C and 70% RH, 1 cm of the sample was weighed out. 3Nitride phosphors obtained in the various examples and comparative examples were filled into a dedicated tubular container, and then dry air at a constant pressure was introduced. The specific surface area was read by the pressure difference, and the average particle size was calculated by the FSSS method. The results are shown in Table 2.

[0185] For the nitride phosphors obtained in each embodiment and comparative example, the volumetric particle size distribution was measured using a particle size distribution measuring device based on laser diffraction (MALVERN PANALYTICAL, product name: MASTER SIZER3000). The cumulative frequency from the small diameter side of the particle size distribution corresponding to the 50% volume average particle size (median particle size: Dm) and the logarithmic standard deviation (σlog) 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 air permeation to the volume average particle size (Dm).

[0186] For the nitride phosphors obtained in each embodiment and comparative example, the emission spectra were measured by irradiating each nitride phosphor with light of a peak emission wavelength of 450 nm using a quantum efficiency measuring device (manufactured by Otsuka Electronics Co., Ltd., product name: QE-2000). The chromaticity coordinates (x, y), luminance (Y), luminance intensity (ENG), and half-width at half-maximum (WHM) of the emission peak were measured from the obtained emission spectra. The results are shown in Table 2.

[0187]

[0188] SEM images

[0189] SEM images of the nitride phosphors obtained in Examples 1-9 and Comparative Examples 1-4 were obtained using a scanning electron microscope (SEM; manufactured by Hitachi High-Technologies, Inc., product name: SU3500). Figure 1 For comparison example 1, Figure 2 This is a SEM image of the nitride phosphor from Example 1. Figure 3 For comparison example 2, Figures 4-6 The images shown are SEM images of the nitride phosphors from Examples 2 to 4, in sequence. Figure 7 For comparison example 3, Figures 8-11 The images shown are SEM images of the nitride phosphors from Examples 5 to 8, in sequence. Figure 12 For comparison example 4, Figure 13 This is a SEM image of the nitride phosphor of Example 9.

[0190] Compared with the nitride phosphors of the comparative examples, it can be confirmed that the nitride phosphors obtained in the examples have average sphericity and average aspect ratio within a given range, and are large particles with improved σlog, D / Dm and good homogeneity.

[0191] The creation of light-emitting devices

[0192] Using the nitride phosphors obtained in the various embodiments and comparative examples, a first light-emitting device, a second light-emitting device, and a third light-emitting device were fabricated as described below.

[0193] First light-emitting device

[0194] An LED chip made of nitride semiconductor with a peak emission wavelength of 455nm was prepared as the light-emitting element. For example... Figure 14 As shown, the light-emitting element 10 is disposed on the concave bottom surface of the molded body 40, and the light-emitting element 10 is connected to the first lead 20 and the second lead 30 respectively by wires 60. The first phosphor (SCASN) of the nitride phosphor obtained in Example 1 or Comparative Example 1, having Y3(Al,Ga)5O 12 The second fluorophore (GYAG) of the Ce-based fluorophore, possessing Y3Al5O 12 The third phosphor (YAG) with Ce composition, and phosphors with K2[Si 1-b Mn b The fourth phosphor (KSF) of composition F6 (0 < b < 0.2) is combined according to the mixing ratios recorded in Table 3, such that the chromaticity coordinates (x, y) of the emitted color are approximately x = 0.346 and y = 0.355 (color temperature approximately 5000K). This mixture is then added to silicone resin for mixing, dispersing the phosphor in the silicone resin to obtain a composition for a wavelength conversion component. This composition for a wavelength conversion component is injected into the recess of the molded body 40, and the silicone resin is cured to form a fluorescent component 50, thus obtaining the first light-emitting device.

[0195] Second light-emitting device

[0196] The first phosphor (SCASN), which is the nitride phosphor obtained in Example 1 or Comparative Example 1, has Y3Al5O 12 The second phosphor, composed of Ce, was combined according to the mixing ratios described in Table 4, such that the chromaticity coordinates (x, y) of the mixed light emitted by the light-emitting device were approximately x=0.563 and y=0.416 (ochre). It was then added to silicone resin for mixing, and the phosphor was dispersed in the silicone resin to obtain a composition for fluorescent components. Otherwise, the same operation as the first light-emitting device was performed to obtain the second light-emitting device.

[0197] Third light-emitting device

[0198] Nitride phosphors obtained in Examples 1 to 10 or Comparative Examples 1 to 4 were added relative to 100 parts by mass of silicone resin in such a manner as shown in Table 5. After mixing and dispersing, the composition for fluorescent components was further obtained by degassing. Otherwise, the same operation as the first light-emitting device was performed to obtain the third light-emitting device.

[0199] Evaluation of light-emitting devices

[0200] The relative luminous flux (%) of the above-obtained light-emitting device was measured as follows.

[0201] The luminous flux of the first and second luminous devices was measured using an integrating total luminous flux measuring device. The relative luminous flux of the first luminous device is shown in Table 3, and the relative luminous flux of the second luminous device is shown in Table 4.

[0202] Regarding the chromaticity of the third light-emitting device, the chromaticity coordinates (x, y) in the chromaticity coordinate system of the CIE 1931 chromaticity diagram were determined using an optical measurement system combining a multi-channel beam splitter and an integrating sphere. Furthermore, in each embodiment and comparative example, specifically, the chromaticity coordinates (x, y) of the five light-emitting devices were determined, and their arithmetic mean was used as the chromaticity coordinates of the light-emitting devices in each embodiment and comparative example. It should be noted that the dominant wavelength of each light-emitting device is: in the JIS Z8701 chromaticity diagram, the chromaticity point W(x, y) connected to the white light-emitting device is... w =0.33333、y w =0.33333) is the wavelength of the point on the chromaticity diagram where the straight line extension of the chromaticity coordinates (x,y) of each light-emitting device intersects the spectral trajectory.

[0203] The luminous flux of the third luminous device was measured using an integrating total luminous flux measuring device. The following relative luminous fluxes are shown in Table 5: relative luminous flux of the luminous device using the nitride phosphor of Example 1 when the luminous flux of the luminous device using the nitride phosphor of Comparative Example 1 is used as a reference (100%); relative luminous flux of the luminous device using the nitride phosphor of Examples 2 to 4 when the luminous flux of the luminous device using the nitride phosphor of Comparative Example 3 is used as a reference (100%); relative luminous flux of the luminous device using the nitride phosphor of Examples 5 to 8 when the luminous flux of the luminous device using the nitride phosphor of Comparative Example 4 is used as a reference (100%); relative luminous flux of the luminous device using the nitride phosphor of Example 9 when the luminous flux of the luminous device using the nitride phosphor of Comparative Example 4 is used as a reference (100%).

[0204]

[0205]

[0206]

[0207] As shown in Tables 3-5, the luminous flux of the light-emitting device using the nitride phosphor in the examples is increased.

Claims

1. A nitride fluorescent material comprising, in a composition: a Group 2 element selected from at least one of Mg, Ca, Sr, and Ba, Eu, Si, Al, and N， wherein a ratio of a total molar content of the Group 2 element and Eu to a molar content of Al in the composition is 0.8 or more and 1.1 or less, a ratio of a molar content of Eu is 0.002 or more and 0.08 or less, a ratio of a molar content of Si is 0.8 or more and 1.2 or less, a ratio of a total molar content of Si and Al is 1.8 or more and 2.2 or less, an average value of an aspect ratio as a ratio of a short diameter to a long diameter is 0.72 or more and 0.77 or less, and an average circularity is 0.82 or more and 0.92 or less.

2. The nitride fluorescent material according to claim 1, having a volume average particle diameter of 20 μm or more and 40 μm or less.

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

4. The nitride fluorescent material according to claim 1, wherein a logarithmic standard deviation of a particle size distribution on a volume basis of a particle diameter is 0.25 or more and less than 0.

38.

5. The nitride fluorescent material according to claim 1, having a composition represented by the following formula (I), M a s Sr t Eu u Si v Al w N x (I) In formula (I), M a is a Group 2 element including at least one selected from Mg, Ca, and Ba, s, t, u, v, w, and x 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.

6. The nitride fluorescent material according to claim 5, wherein in the formula (I), s, t, and u satisfy 0.94≤s+t+u≤1.

10.

7. A light emitting device comprising: a fluorescent member comprising the nitride fluorescent material according to any one of claims 1 to 6, and a light emitting element having a light emitting peak wavelength in a range of 365 nm or more and 500 nm or less.

8. The light emitting device according to claim 7, wherein the fluorescent member further comprises at least one of fluorescent materials having a composition represented by any one of the following formulas, (Y,Gd,Tb,Lu)3(Al,Ga)5O 12 :Ce (IIa) (Ca,Sr,Ba)2Si04:Eu (IIb) Si 6-p Al p O p N 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).

9. The light emitting device according to claim 7, wherein the fluorescent member further comprises at least one of fluorescent materials having a composition represented by any one of the following formulas, A 1 c [M 1 1-b Mn b F d ] (IIj) In formula (IIj), A 1 comprising at least one selected from the group consisting of Li, Na, K, Rb, and Cs, M 1 comprising at least one of Si and Ge, optionally further comprising or not comprising at least one element selected from the group consisting of Group 4 elements and Group 14 elements, b satisfies 0 < b < 0.2, c is the absolute value of the charge of the [M 1 1-b Mn b F d d satisfies 5 < d < 7, A 2 f [M 2 1-e Mn e F g ] (IIk) In formula (IIk), A 2 M comprises at least one selected from Li, Na, K, Rb, and Cs 2 M comprises at least Si and Al, and optionally further comprises or does not comprise at least one element selected from a Group 4 element, a Group 13 element, and a Group 14 element, e satisfies 0 < e < 0.2, 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.

10. The light emitting device according to claim 8, wherein the fluorescent member further comprises at least one of fluorescent materials having a composition represented by any one of the following formulas, A 1 c [M 1 1-b Mn b F d ] (IIj) In formula (IIj), A 1 comprising at least one selected from the group consisting of Li, Na, K, Rb, and Cs, M 1 comprising at least one of Si and Ge, optionally further comprising or not comprising at least one element selected from the group consisting of Group 4 elements and Group 14 elements, b satisfies 0 < b < 0.2, c is the absolute value of the charge of the [M 1 1-b Mn b F d ] ion, d satisfies 5 < d < 7, A 2 f [M 2 1-e Mn e F g ] (IIk) In formula (IIk), A 2 comprising at least one selected from the group consisting of Li, Na, K, Rb, and Cs, M 2 comprising at least Si and Al, optionally further comprising or not comprising at least one element selected from the group consisting of a Group 4 element, a Group 13 element, and a Group 14 element, e satisfies 0 < e < 0.2, 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.

Images