Phosphor powder, composite, and light-emitting device

Abstract

Provided is a phosphor powder which contains one or more types of phosphor particles selected from the group consisting of CASN phosphor particles and SCASN phosphorl particles. The percentage increase in oxygen amount of the phosphor powder, as determined using method 1, is 100-500%. (Method 1) If X1 (mass%) denotes the content of oxygen in the phosphor powder and X2 (mass%) denotes the content of oxygen in the phosphor powder after 5 g of the phosphor powder is held for 53 hours in an atmosphere having a temperature of 130°C, a relative humidity of 98% and a pressure of 0.16 MPaG using a pressure cooker tester, then the percentage increase in oxygen amount (%) is denoted by 100×X2 / X1.

Description

Phosphor powder, composite and light-emitting device

[0001] The present invention relates to a phosphor powder, a composite, and a light-emitting device.

[0002] In order to manufacture white LEDs, research has been conducted into red phosphors that convert blue light from a blue LED chip into red light. Known red phosphors include so-called CASN phosphors and SCASN phosphors. Patent Document 1 discloses a nitride phosphor having the general formula M ａ Sr ｂ Ca ｃ Al ｄ Si ｅ N ｆ and 4000 mW / mm ２ The document describes a phosphor characterized by a quantum efficiency maintenance rate of 85% or more upon photoexcitation. In this general formula, M represents an activator element, and the following relationships are satisfied: 0<a<0.05, 0.95≦b≦1, 0≦c<0.1, a+b+c=1, 0.7≦d≦1.3, 0.7≦e≦1.3, and 2.5≦f≦3.5.

[0003] JP 2019-077800 A

[0004] The present invention provides a phosphor powder with improved reliability, and a composite body and a light-emitting device that use the phosphor powder with improved reliability.

[0005] The present inventors have conducted extensive research to solve the above problems, and as a result have found that a phosphor powder containing one or more types of phosphor particles selected from the group consisting of CASN phosphor particles and SCASN phosphor particles, and having an oxygen content increase rate within a specific range, can improve reliability, thereby completing the present invention.

[0006] According to the present invention, there are provided the following phosphor powder, composite body, and light-emitting device.

[0007] [1] A phosphor powder containing one or more phosphor particles selected from the group consisting of CASN phosphor particles and SCASN phosphor particles, wherein the oxygen content increase rate of the phosphor powder is 100% or more and 500% or less by the following method 1. (Method 1) The oxygen content rate of the phosphor powder is X １ (mass %), and the oxygen content of the phosphor powder after 5 g of the phosphor powder was kept at 130° C. under an atmosphere of 98% relative humidity and 0.16 MPaG for 53 hours using a pressure cooker tester was determined as X ２ (mass%), 100 x X ２ / X １ is the oxygen content increase rate (%). [2] The X １ [3] The phosphor powder according to [1], wherein the general formula: Eu ａ Sr ｂ Ca ｃ Al ｄ Si ｅ N ｆ O ｇ The phosphor powder according to [1] or [2] contains phosphor particles represented by the formula: 0<a<1.00, 0<b<1.00, 0<c<1.00, 0.70<a+b+c<1.30, 0.70<d<1.30, 0.70<e<1.30, 0<f<3.00, 0<g<3.00, 2.50<f+g<3.50. [4] The phosphor powder according to [3], wherein a<0.30. [5] The phosphor powder according to [3] or [4], wherein b>0.50. [6] The phosphor powder according to any one of [3] to [5], wherein the molar ratio of b / (b+c) of the phosphor powder is 0.96 or more and 0.99 or less. [7] The volume-based median diameter D of the phosphor powder measured by a laser diffraction scattering method ５０[8] The phosphor powder according to any one of [1] to [7], which has an internal quantum efficiency of 60.0% or more when excited by light with a wavelength of 455 nm. [9] The phosphor powder according to any one of [1] to [8], which has an external quantum efficiency of 60.0% or more when excited by light with a wavelength of 455 nm.

[10] The phosphor powder according to any one of [1] to [9], which has a relative fluorescence intensity decrease rate of 10.0% or less when measured by the following method 2. (Method 2) The relative fluorescence intensity of the phosphor powder measured using a spectrophotometer is measured by Y １ (%), and the relative fluorescence intensity of the phosphor powder after 5 g of the phosphor powder was kept at 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours using a pressure cooker tester was measured. ２ (%), 100 x (Y １ -Y ２ ) / Y １ is the relative fluorescence intensity decrease rate (%).

[11] The Y １

[12] The phosphor powder according to any one of [1] to

[11] , wherein the absorptance of the phosphor powder for light with a wavelength of 455 nm measured using a spectrophotometer is reduced by 5.0% or less. (Method 3) The absorptance of the phosphor powder for light with a wavelength of 455 nm measured using a spectrophotometer is reduced by 5.0% or less. １ (%), and the absorptivity of the phosphor powder with respect to light having a wavelength of 455 nm after 5 g of the phosphor powder was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours using a pressure cooker tester. ２ (%), 100 x (Z １ -Z ２ ) / Z １ is the absorption rate reduction rate (%).

[13] The Z １

[14] A composite comprising the phosphor powder according to any one of [1] to

[13] and an encapsulant that encapsulates the phosphor powder.

[15] The composite according to

[14] , wherein the encapsulant contains one or more materials selected from the group consisting of silicone resin, epoxy resin, urethane resin, glass, and ceramics.

[16] A light-emitting device comprising: a light-emitting element that emits excitation light; and the composite according to

[14] or

[15] that converts the wavelength of the excitation light.

[0008] According to the present invention, it is possible to provide a phosphor powder with improved reliability, as well as a composite and a light emitting device using the phosphor powder with improved reliability.

[0009] FIG. 1 is a schematic cross-sectional view showing an example of the structure of a light-emitting device.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, similar components are given similar reference numerals, and descriptions thereof will be omitted where appropriate. To avoid complexity, when multiple identical components appear in the same drawing, only one of the components may be given a reference numeral, and not all of the components may be given a reference numeral. The drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to actual objects.

[0011] In this embodiment, "A to B" indicating a numerical range means A or more and B or less unless otherwise specified.

[0012] <Phosphor Powder> The phosphor powder of this embodiment contains one or more types of phosphor particles selected from the group consisting of CASN phosphor particles and SCASN phosphor particles. The phosphor powder of this embodiment preferably contains SCASN phosphor particles from the viewpoint of further improving the fluorescent properties of the phosphor powder.

[0013] The CASN phosphor particles of this embodiment are (Si, Al)—N ４ It is composed of regular tetrahedrons bonded together, and Ca atoms are located in the gaps between the framework. ２＋ A part of Eu acts as a luminescence center. ２＋The SCASN phosphor particles of this embodiment are (Si, Al)—N ４ It is composed of regular tetrahedrons bonded together, and some of the Ca atoms located in the gaps of the framework are replaced with Sr atoms and form a solid solution. ２＋ A part of Eu acts as a luminescence center. ２＋ These are phosphor particles in which an activator element such as

[0014] The phosphor powder of this embodiment has an oxygen content increase rate of 100% or more and 500% or less before and after the pressure cooker test. Here, the oxygen content increase rate is calculated by multiplying the oxygen content of the phosphor powder by X １ (mass %), and the oxygen content of the phosphor powder after 5 g of the phosphor powder was kept at 130° C. under an atmosphere of 98% relative humidity and 0.16 MPaG for 53 hours using a pressure cooker tester was determined as X ２ (mass%), 100 x X ２ / X １ It is calculated as follows.

[0015] According to the study of the present inventors, it was found that there is a correlation between the rate of increase in the amount of oxygen in the phosphor powder before and after the pressure cooker test and the reliability of the phosphor powder. １ (mass %), and the oxygen content of the phosphor powder after 5 g of the phosphor powder was kept at 130° C. under an atmosphere of 98% relative humidity and 0.16 MPaG for 53 hours using a pressure cooker tester was determined as X ２ (mass%), 100 x X ２ / X １ The inventors have found that the reliability of the phosphor powder can be improved by setting the oxygen content increase rate calculated by the above formula as an index and setting the oxygen content increase rate within the range of 100% to 500%, and have completed the present invention.

[0016] From the viewpoint of further improving the reliability of the phosphor powder, the oxygen content increase rate of the phosphor powder of this embodiment is 100% or more, preferably 101% or more, more preferably 103% or more, and is 500% or less, preferably 460% or less, more preferably 430% or less, even more preferably 400% or less, even more preferably 380% or less, even more preferably 350% or less, even more preferably 300% or less, even more preferably 250% or less, even more preferably 200% or less, and even more preferably 180% or less.

[0017] From the viewpoint of further improving the reliability of the phosphor powder, the oxygen content increase rate of the phosphor powder of this embodiment is 100% or more and 500% or less, preferably 100% or more and 460% or less, more preferably 100% or more and 430% or less, even more preferably 100% or more and 400% or less, even more preferably 100% or more and 380% or less, even more preferably 100% or more and 350% or less, even more preferably 100% or more and 300% or less, even more preferably 100% or more and 250% or less, even more preferably 101% or more and 200% or less, and even more preferably 103% or more and 180% or less.

[0018] The oxygen content X of the phosphor powder of this embodiment １ From the viewpoint of further improving the reliability of the phosphor powder, the oxygen content X of the phosphor powder after the pressure cooker test of this embodiment is preferably 0.10 mass % or more, more preferably 0.50 mass % or more, even more preferably 1.00 mass % or more, even more preferably 1.30 mass % or more, and even more preferably 1.50 mass % or more, and is preferably 5.00 mass % or less, more preferably 4.00 mass % or less, even more preferably 3.50 mass % or less, even more preferably 3.00 mass % or less, even more preferably 2.50 mass % or less, and even more preferably 2.40 mass % or less. ２From the viewpoint of further improving the reliability of the phosphor powder, is preferably 0.10 mass% or more, more preferably 0.50 mass% or more, even more preferably 1.00 mass% or more, even more preferably 1.30 mass% or more, even more preferably 1.50 mass% or more, and is preferably 12.00 mass% or less, more preferably 11.00 mass% or less, even more preferably 10.00 mass% or less, even more preferably 9.50 mass% or less, even more preferably 9.00 mass% or less, even more preferably 7.00 mass% or less, even more preferably 5.00 mass% or less, even more preferably 4.00 mass% or less.

[0019] The oxygen content X of the phosphor powder of this embodiment １ is preferably 0.10 mass % or more and 5.00 mass % or less, more preferably 0.10 mass % or more and 4.00 mass % or less, even more preferably 0.50 mass % or more and 3.50 mass % or less, even more preferably 1.00 mass % or more and 3.00 mass % or less, even more preferably 1.30 mass % or more and 2.50 mass % or less, and even more preferably 1.50 mass % or more and 2.40 mass % or less, from the viewpoint of further improving the reliability of the phosphor powder. ２ From the viewpoint of further improving the reliability of the phosphor powder, is preferably 0.10 mass% or more and 12.00 mass% or less, more preferably 0.10 mass% or more and 11.00 mass% or less, even more preferably 0.10 mass% or more and 10.00 mass% or less, even more preferably 0.10 mass% or more and 9.50 mass% or less, even more preferably 0.50 mass% or more and 9.00 mass% or less, even more preferably 1.00 mass% or more and 7.00 mass% or less, even more preferably 1.30 mass% or more and 5.00 mass% or less, and even more preferably 1.50 mass% or more and 4.00 mass% or less.

[0020] In this embodiment, the oxygen content (mass %) of the phosphor powder can be determined by, for example, weighing out 0.03 g of the phosphor powder and measuring the oxygen content with an oxygen / nitrogen analyzer.

[0021] The phosphor powder of this embodiment can be obtained by appropriately selecting the raw materials, the ratio of each raw material used, the manufacturing procedure and manufacturing conditions, etc. Regarding the selection of raw materials and the ratio of raw materials, it is preferable to use a larger amount of Sr-containing raw material and add a "core" (described later). Regarding the manufacturing procedure and manufacturing conditions, it is preferable to perform atmospheric heating treatment under appropriate conditions, and to perform firing and annealing using a sealed container. Details of these will be described later.

[0022] (Crystal structure, elemental composition, etc.) The phosphor particles of this embodiment are made of CaAlSiN ３ The general formula Eu ａ Sr ｂ Ca ｃ Al ｄ Si ｅ N ｆ O ｇ In this general formula, 0<a<1.00, 0<b<1.00, 0<c<1.00, 0.70<a+b+c<1.30, 0.70<d<1.30, 0.70<e<1.30, 0<f<3.00, 0<g<3.00, 2.50<f+g<3.50.

[0023] The crystalline phase can be confirmed by powder X-ray diffraction. A single crystalline phase is preferable, but other phases may be included as long as they do not significantly affect the phosphor properties. The presence or absence of other phases can be determined by, for example, the presence or absence of peaks other than those due to the target crystalline phase by powder X-ray diffraction.

[0024] Regarding a, from the viewpoint of improving the fluorescent properties of the phosphor powder, it is preferable that a is 0.01<a, more preferably 0.03<a, even more preferably 0.05<a, even more preferably 0.06<a, and even more preferably 0.07<a, and it is also preferable that a is <0.30, more preferably a<0.25, even more preferably a<0.20, even more preferably a<0.15, and even more preferably a<0.10. Furthermore, from the viewpoint of improving the fluorescent properties of the phosphor powder, it is preferable that a is 0.01<a<0.30, more preferably 0.03<a<0.25, even more preferably 0.05<a<0.20, even more preferably 0.06<a<0.15, and even more preferably 0.07<a<0.10.

[0025] From the viewpoint of improving the fluorescent properties of the phosphor powder, b is preferably 0.50<b, more preferably 0.60<b, even more preferably 0.70<b, even more preferably 0.80<b, and even more preferably 0.83<b, and is preferably b<0.99, more preferably b<0.95, and even more preferably b<0.90. Also, from the viewpoint of improving the fluorescent properties of the phosphor powder, b is preferably 0.50<b<0.99, more preferably 0.60<b<0.99, even more preferably 0.70<b<0.99, even more preferably 0.80<b<0.95, and even more preferably 0.83<b<0.90.

[0026] As another indicator of "high Sr content," the molar ratio b / (b+c) is preferably 0.96 or more, more preferably 0.97 or more, even more preferably 0.98 or more, and preferably 0.99 or less, from the viewpoint of improving the fluorescent properties of the phosphor powder. Also, the molar ratio b / (b+c) is preferably 0.96 or more and 0.99 or less, more preferably 0.97 or more and 0.99 or less, even more preferably 0.98 or more and 0.99 or less, from the viewpoint of improving the fluorescent properties of the phosphor powder.

[0027] Regarding c, from the viewpoint of improving the fluorescent properties of the phosphor powder, 0<c, preferably c<0.20, more preferably c<0.15, even more preferably c<0.10, even more preferably c<0.05, and even more preferably c<0.03. Also, regarding c, from the viewpoint of improving the fluorescent properties of the phosphor powder, preferably 0<c<0.20, more preferably 0<c<0.15, even more preferably 0<c<0.10, even more preferably 0<c<0.05, and even more preferably 0<c<0.03.

[0028] From the viewpoint of improving the fluorescent properties of the phosphor powder, d is preferably 0.80<d, more preferably 0.85<d, even more preferably 0.90<d, and even more preferably 0.95<d, and is preferably d<1.20, more preferably d<1.15, even more preferably d<1.10, and even more preferably d<1.05. Also, from the viewpoint of improving the fluorescent properties of the phosphor powder, d is preferably 0.80<d<1.20, more preferably 0.85<d<1.15, even more preferably 0.90<d<1.10, and even more preferably 0.95<d<1.05.

[0029] From the viewpoint of improving the fluorescent properties of the phosphor powder, e is preferably 0.75<e, more preferably 0.80<e, even more preferably 0.85<e, and even more preferably 0.90<e, and is preferably e<1.20, more preferably e<1.10, even more preferably e<1.05, even more preferably e<1.00, and even more preferably e<0.97. Also, from the viewpoint of improving the fluorescent properties of the phosphor powder, e is preferably 0.75<e<1.20, more preferably 0.75<e<1.10, even more preferably 0.80<e<1.05, even more preferably 0.85<e<1.00, and even more preferably 0.90<e<0.97.

[0030] From the viewpoint of improving the fluorescent properties of the phosphor powder, f is preferably 2.55 < f, more preferably 2.60 < f, even more preferably 2.65 < f, even more preferably 2.70 < f, and even more preferably 2.75 < f, and is preferably f < 3.40, more preferably f < 3.20, even more preferably f < 3.10, even more preferably f < 3.00, even more preferably f < 2.90, even more preferably f < 2.85, and even more preferably f < 2.82. From the viewpoint of improving the fluorescent properties of the phosphor powder, f is preferably 2.55 < f < 3.40, more preferably 2.55 < f < 3.20, even more preferably 2.55 < f < 3.10, even more preferably 2.60 < f < 3.00, even more preferably 2.65 < f < 2.90, even more preferably 2.70 < f < 2.85, and even more preferably 2.75 < f < 2.82.

[0031] From the viewpoint of improving the fluorescent properties of the phosphor powder, g is preferably 0.01 < g, more preferably 0.05 < g, even more preferably 0.10 < g, and even more preferably 0.15 < g, and is preferably g < 0.80, more preferably g < 0.50, even more preferably g < 0.40, even more preferably g < 0.35, even more preferably g < 0.30, and even more preferably g < 0.25. Also, from the viewpoint of improving the fluorescent properties of the phosphor powder, g is preferably 0.01 < g < 0.80, more preferably 0.01 < g < 0.50, even more preferably 0.01 < g < 0.40, even more preferably 0.05 < g < 0.35, even more preferably 0.10 < g < 0.30, and even more preferably 0.15 < g < 0.25.

[0032] In this embodiment, the molar ratios of Eu, Sr, Ca, Al, and Si among the molar ratios of each element contained in the phosphor powder can be measured, for example, by dissolving the phosphor powder by a pressurized acid decomposition method, preparing a sample solution, and performing quantitative elemental analysis on the obtained sample solution using an ICP optical emission spectrometer. In this embodiment, the molar ratios of N and O among the molar ratios of each element contained in the phosphor powder can be determined, for example, by weighing out 0.03 g of the phosphor powder and measuring the oxygen and nitrogen contents using an oxygen / nitrogen analyzer.

[0033] (Median diameter D ５０ ) Median diameter D of the phosphor particles of this embodiment ５０ From the viewpoint of further improving the reliability of the phosphor powder, the median diameter is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, even more preferably 15 μm or more, even more preferably 17 μm or more, even more preferably 20 μm or more, and is preferably 40 μm or less, more preferably 36 μm or less, even more preferably 33 μm or less, even more preferably 30 μm or less. In applications where blue light from a blue LED is converted into red light, a median diameter of this order is preferred in terms of the balance of various performance properties such as brightness, conversion efficiency, and reliability.

[0034] The median diameter D of the phosphor particles of this embodiment ５０ From the viewpoint of further improving the reliability of the phosphor powder, the average particle diameter is preferably 1 μm or more and 40 μm or less, more preferably 5 μm or more and 40 μm or less, even more preferably 10 μm or more and 40 μm or less, even more preferably 15 μm or more and 36 μm or less, even more preferably 17 μm or more and 33 μm or less, and even more preferably 20 μm or more and 30 μm or less.

[0035] In this embodiment, the median diameter D of the phosphor powder ５０ The median diameter D can be measured as a volume-based value, for example, by a laser diffraction scattering method. ５０ The adjustment of can be carried out by appropriately applying known means such as pulverization, sieving, etc. Details will be described later.

[0036] (Absorption coefficient) From the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder, the absorption coefficient Z1 of the phosphor powder of this embodiment for light with a wavelength of 455 nm is preferably 90.0% or more, more preferably 92.0% or more, even more preferably 94.0% or more, even more preferably 95.0% or more, and is preferably 99.9% or less, more preferably 99.0% or less, even more preferably 98.0% or less.

[0037] The absorptance Z1 of the phosphor powder of this embodiment for light with a wavelength of 455 nm is preferably 90.0% or more and 99.9% or less, more preferably 92.0% or more and 99.9% or less, even more preferably 94.0% or more and 99.0% or less, and even more preferably 95.0% or more and 98.0% or less, from the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder.

[0038] In this embodiment, the absorptance Z1 of the phosphor powder for light with a wavelength of 455 nm can be determined, for example, by the following method. First, the phosphor powder is filled into a concave cell so that the surface is smooth, and the cell is attached to the opening of an integrating sphere. Next, monochromatic light with a wavelength of 455 nm is split from a Xe lamp, which serves as a light source, and introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. This monochromatic excitation light is irradiated onto the phosphor powder, and the fluorescence spectrum is measured using a spectrophotometer. From the obtained fluorescence spectrum data, the luminescence intensity of the phosphor powder is determined, and the number of reflected excitation light photons (Qref) and the number of fluorescent photons (Qem) are calculated. The number of reflected excitation light photons is calculated in the wavelength range of 450 to 465 nm, and the number of fluorescent photons is calculated in the wavelength range of 465 to 800 nm. Additionally, using the same device, a standard reflector with a reflectance of 99% (Spectralon (registered trademark) manufactured by Labsphere) is attached to the opening of the integrating sphere to measure the spectrum of excitation light with a wavelength of 455 nm. At this time, the number of excitation light photons (Qex) is calculated from the spectrum in the wavelength range of 450 to 465 nm. From the above calculation results, the absorptance Z1 of the phosphor for 455 nm light is calculated using the following formula: Absorptance Z1 for 455 nm light = ((Qex - Qref) / Qex) x 100

[0039] (Internal quantum efficiency) The internal quantum efficiency of the phosphor powder of this embodiment when excited by light with a wavelength of 455 nm is, from the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder, preferably 60.0% or more, more preferably 64.0% or more, even more preferably 67.0% or more, even more preferably 70.0% or more, and preferably 99.0% or less, more preferably 90.0% or less, even more preferably 85.0% or less, even more preferably 80.0% or less.

[0040] The internal quantum efficiency of the phosphor powder of this embodiment when excited by light with a wavelength of 455 nm is preferably 60.0% or more and 99.0% or less, more preferably 64.0% or more and 90.0% or less, even more preferably 67.0% or more and 85.0% or less, and even more preferably 70.0% or more and 80.0% or less, from the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder.

[0041] In this embodiment, the internal quantum efficiency of the phosphor powder when excited by light with a wavelength of 455 nm can be calculated, for example, from the calculation results of the number of reflected excitation light photons (Qref), the number of fluorescent photons (Qem), and the number of excitation light photons (Qex) using the following formula: Internal quantum efficiency = (Qem / (Qex-Qref)) x 100

[0042] (External quantum efficiency) From the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder, the external quantum efficiency of the phosphor powder of this embodiment when excited by light with a wavelength of 455 nm is preferably 60.0% or more, more preferably 63.0% or more, even more preferably 66.0% or more, even more preferably 68.0% or more, and preferably 99.0% or less, more preferably 90.0% or less, even more preferably 85.0% or less, even more preferably 80.0% or less.

[0043] The external quantum efficiency of the phosphor powder of this embodiment when excited by light with a wavelength of 455 nm is preferably 60.0% or more and 99.0% or less, more preferably 63.0% or more and 90.0% or less, even more preferably 66.0% or more and 85.0% or less, and even more preferably 68.0% or more and 80.0% or less, from the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder.

[0044] In this embodiment, the external quantum efficiency of the phosphor powder when excited by light with a wavelength of 455 nm can be determined, for example, from the calculation results of the number of reflected excitation light photons (Qref), the number of fluorescent photons (Qem), and the number of excitation light photons (Qex) described above, based on the following calculation formula: External quantum efficiency = (Qem / Qex) x 100 From the above formula, the relationship between the external quantum efficiency, the absorptance for 455 nm light, and the internal quantum efficiency can be expressed as follows: External quantum efficiency = absorptance for 455 nm light x internal quantum efficiency

[0045] (Peak Wavelength, Half Width) The peak wavelength of the fluorescence spectrum when the phosphor powder of this embodiment is irradiated with light having a wavelength of 455 nm is preferably 600 nm or more, more preferably 610 nm or more, even more preferably 620 nm or more, even more preferably 630 nm or more, even more preferably 633 nm or more, from the viewpoint of further improving the reliability of the phosphor powder and the performance balance of the fluorescence properties. And, preferably 670 nm or less, more preferably 660 nm or less, even more preferably 650 nm or less, even more preferably 645 nm or less, even more preferably 643 nm or less. Furthermore, from the viewpoint of further improving the reliability of the phosphor powder and the performance balance of the fluorescence properties, the half width of the peak of this fluorescence spectrum is preferably 70.0 nm or more, more preferably 71.0 nm or more, even more preferably 72.0 nm or more, even more preferably 73.0 nm or more, and preferably 77.0 nm or less, more preferably 76.0 nm or less, even more preferably 75.0 nm or less. In this embodiment, the fluorescence spectrum when the phosphor powder is irradiated with light having a wavelength of 455 nm can be measured, for example, by a method similar to the method for measuring the absorptance Z1 described above.

[0046] When the phosphor powder of this embodiment is irradiated with light having a wavelength of 455 nm, the peak wavelength of the fluorescence spectrum is preferably 600 nm to 670 nm, more preferably 610 nm to 660 nm, even more preferably 620 nm to 650 nm, even more preferably 630 nm to 645 nm, and even more preferably 633 nm to 643 nm, from the viewpoint of further improving the reliability of the phosphor powder and the performance balance of the fluorescence properties. Furthermore, the half-width of the peak of this fluorescence spectrum is preferably 70.0 nm to 77.0 nm, more preferably 71.0 nm to 77.0 nm, even more preferably 72.0 nm to 76.0 nm, and even more preferably 73.0 nm to 75.0 nm, from the viewpoint of further improving the reliability of the phosphor powder and the performance balance of the fluorescence properties.

[0047] (Relative Fluorescence Intensity) Relative fluorescence intensity Y of the phosphor powder of this embodiment １ From the viewpoint of further improving the performance balance between the reliability and the fluorescent properties of the phosphor powder, the relative fluorescence intensity Y is preferably 150% or more, more preferably 170% or more, even more preferably 190% or more, even more preferably 200% or more, even more preferably 210% or more, even more preferably 220% or more, and even more preferably 225% or more. １ The upper limit is not particularly limited, but may be, for example, 400% or less, 350% or less, 300% or less, 280% or less, or 260% or less.

[0048] The relative fluorescence intensity Y of the phosphor powder of this embodiment １ From the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder, is preferably 150% or more, more preferably 170% or more and 400% or less, even more preferably 190% or more and 400% or less, even more preferably 200% or more and 350% or less, even more preferably 210% or more and 300% or less, even more preferably 220% or more and 280% or less, and even more preferably 225% or more and 260% or less.

[0049] In this embodiment, the relative fluorescence intensity Y １For example, the peak intensity of the emission spectrum obtained by irradiating YAG:Ce with monochromatic light of 455 nm is set to 100%, and the peak intensity in the fluorescence spectrum measured by the same method as the above-mentioned method for measuring the absorptance Z1 can be calculated by expressing the peak intensity in terms of relative peak intensity (%). １ is a relative value to a standard sample.

[0050] (Absorbency after Pressure Cooker Test) Using a pressure cooker tester, 5 g of the phosphor powder of this embodiment was held at 130° C. under an atmosphere of 98% relative humidity and 0.16 MPaG for 53 hours, and then the absorptivity Z of the phosphor powder of this embodiment for light with a wavelength of 455 nm was measured. ２ From the viewpoint of further improving the reliability of the phosphor powder, the absorptance Z of the phosphor powder for light with a wavelength of 455 nm is preferably 92.0% or more, more preferably 93.0% or more, even more preferably 94.0% or more, and even more preferably 94.5% or more, and is preferably 99.9% or less, more preferably 99.0% or less, and even more preferably 98.5% or less. ２ can be determined, for example, by a method similar to the method for measuring the absorptance Z1 described above.

[0051] Using a pressure cooker tester, 5 g of the phosphor powder of this embodiment was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours, and then the absorptance Z of the phosphor powder of this embodiment for light with a wavelength of 455 nm was measured. ２ From the viewpoint of further improving the reliability of the phosphor powder, the content is preferably 92.0% or more and 99.9% or less, more preferably 93.0% or more and 99.9% or less, even more preferably 94.0% or more and 99.0% or less, and even more preferably 94.5% or more and 98.5% or less.

[0052] The phosphor powder of this embodiment has a 100×(Z １ -Z ２ ) / Z １From the viewpoint of further improving the reliability of the phosphor powder, the absorption reduction rate (%) calculated by is preferably −5.0% or more, more preferably −1.0% or more, even more preferably 0.0% or more, and is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.0% or less.

[0053] The phosphor powder of this embodiment has a 100×(Z １ -Z ２ ) / Z １ From the viewpoint of further improving the reliability of the phosphor powder, the absorption reduction rate (%) calculated by is preferably −5.0% or more and 5.0% or less, more preferably −5.0% or more and 4.0% or less, even more preferably −5.0% or more and 3.0% or less, even more preferably −1.0% or more and 2.5% or less, and even more preferably 0.0% or more and 2.0% or less.

[0054] (Relative Fluorescence Intensity After Pressure Cooker Test) Using a pressure cooker tester, 5 g of the phosphor powder of this embodiment was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours, and then the relative fluorescence intensity Y ２ In the case where SCASN phosphor particles are included, the relative fluorescence intensity Y of the phosphor powder of this embodiment is preferably 221% or more, more preferably 223% or more, and even more preferably 225% or more, from the viewpoint of further improving the reliability of the phosphor powder, and is preferably 400% or less, more preferably 300% or less, and even more preferably 260% or less. ２ When CASN phosphor particles are included, from the viewpoint of further improving the reliability of the phosphor powder, the ρ is preferably 130% or more, more preferably 150% or more, even more preferably 170% or more, even more preferably 190% or more, even more preferably 200% or more, even more preferably 210% or more, even more preferably 220% or more, and is preferably 400% or less, more preferably 300% or less, even more preferably 260% or less.

[0055] Using a pressure cooker tester, 5 g of the phosphor powder of this embodiment was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours, and then the relative fluorescence intensity Y ２ In the case where the phosphor powder contains SCASN phosphor particles, the relative fluorescence intensity Y of the phosphor powder of this embodiment is preferably 221% or more and 400% or less, more preferably 223% or more and 300% or less, and even more preferably 225% or more and 260% or less, from the viewpoint of further improving the reliability of the phosphor powder. ２ When CASN phosphor particles are included, from the viewpoint of further improving the reliability of the phosphor powder, the ρ is preferably 130% or more and 400% or less, more preferably 150% or more and 400% or less, even more preferably 170% or more and 400% or less, even more preferably 190% or more and 400% or less, even more preferably 200% or more and 400% or less, even more preferably 210% or more and 300% or less, and even more preferably 220% or more and 260% or less.

[0056] The phosphor powder of this embodiment has a 100×(Y １ -Y ２ ) / Y １ From the viewpoint of further improving the reliability of the phosphor powder, the relative fluorescence intensity decrease rate (%) calculated by is preferably −5.0% or more, more preferably −1.0% or more, even more preferably 0.0% or more, and is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 6.0% or less, even more preferably 5.0% or less.

[0057] The phosphor powder of this embodiment has a 100×(Y １ -Y ２ ) / Y １ From the viewpoint of further improving the reliability of the phosphor powder, the relative fluorescence intensity decrease rate (%) calculated by is preferably −5.0% or more and 10.0% or less, more preferably −5.0% or more and 8.0% or less, even more preferably −1.0% or more and 6.0% or less, and even more preferably 0.0% or more and 5.0% or less.

[0058] <Method for Producing Phosphor Powder> The phosphor powder of this embodiment can be obtained by appropriately selecting the raw materials, the ratio of each raw material used, the production procedure, and the production conditions. Specifically, the phosphor powder of this embodiment can be preferably produced through the following steps: a mixing step in which starting materials are mixed to obtain a raw material mixed powder; a firing step in which the raw material mixed powder is fired to obtain a lump-shaped fired powder; a pulverization step in which the lump-shaped fired powder is pulverized; an annealing step in which the powder-shaped fired powder is heat-treated to obtain an annealed powder; an acid treatment step in which the annealed powder is acid-treated to obtain an acid-treated powder; an elutriation step in which fine particles are removed from the acid-treated powder by elutriation; and an atmospheric heat treatment step in which the acid-treated powder is air-heat-treated to obtain an air-heat-treated powder. The production of the phosphor powder may also include additional steps other than those described above.

[0059] (Mixing Step) In the mixing step of this embodiment, the starting materials are mixed to form a mixed raw material powder. From the viewpoint of further improving the fluorescent properties of the phosphor powder, the starting materials of this embodiment preferably contain all of a europium compound, a strontium compound, a calcium compound, silicon nitride, and aluminum nitride, and more preferably contain all of europium oxide, strontium nitride, calcium nitride, silicon nitride, and aluminum nitride. Each starting material of this embodiment is preferably in the form of a powder.

[0060] From the viewpoint of further improving the fluorescent properties of the phosphor powder, the europium compound of this embodiment preferably contains one selected from the group consisting of europium oxide, europium nitride, and europium fluoride, and more preferably contains europium oxide alone.

[0061] In the firing process of this embodiment, europium is divided into those that form a solid solution, those that volatilize, and those that remain as heterogeneous phase components. Heterogeneous phase components containing europium can be removed by acid treatment or the like. However, if too much heterogeneous phase component containing europium is produced, insoluble components are produced by acid treatment, resulting in a decrease in brightness. Furthermore, any heterogeneous phase that does not absorb excess light may remain, and europium may be contained in this heterogeneous phase.

[0062] From the viewpoint of further improving the fluorescent properties of the phosphor powder, the amount of europium compound used in this embodiment is preferably such that a in the general formula in the charging ratio satisfies the relationship 0.05<a<0.15, more preferably 0.07<a<0.10. Incidentally, when core particles described below are used, a in the above inequality does not include the amount of europium in the core particles.

[0063] On the other hand, from the viewpoint of further improving the fluorescent properties of the phosphor powder, the amount of the strontium compound in this embodiment is preferably used in such an amount that b in the above-mentioned general formula in the charging ratio satisfies preferably 0.85<b<1.00, more preferably 0.95<b<0.98. Incidentally, when core particles described below are used, b in the above inequality does not include the amount of strontium in the core particles.

[0064] The starting material (raw material mixed powder) of this embodiment preferably contains SCASN phosphor core particles having a median diameter of 10 μm or more and 20 μm or less. In other words, a portion of the starting material is preferably SCASN phosphor core particles having a median diameter of 10 μm or more and 20 μm or less. From the viewpoint of further improving the fluorescent properties of the phosphor powder, the median diameter of the SCASN phosphor core particles of this embodiment is preferably 10 μm or more, more preferably 15 μm or more, and preferably 20 μm or less, more preferably 17 μm or less. In this specification, these SCASN phosphor core particles are also simply referred to as "core particles" or "cores."

[0065] Although the details are unclear, it is believed that by using core particles, crystallization will proceed from the core particles as the starting point during the subsequent firing process. This is thought to result in a different way of crystal growth compared to firing without core particles (for example, by using cores, it is thought that the composition of each particle will be more uniform than when no cores are used). As a result, it is thought that it will be easier to obtain phosphor powder with improved fluorescent properties.

[0066] The core particles of this embodiment may be, for example, a phosphor powder represented by the same general formula as the phosphor powder of this embodiment described above. In other words, the core particles have the same or similar composition as the phosphor powder of this embodiment, although the increase in oxygen content before and after the pressure cooker test according to the above-mentioned method is not necessarily 100% to 500%.

[0067] When core particles are used, the amount thereof is preferably 7 mass % or more, more preferably 9 mass % or more, of the total amount of the raw material mixed powder, from the viewpoint of further improving the fluorescent properties of the phosphor powder, and is preferably 13 mass % or less, more preferably 11 mass % or less.

[0068] The core particles can be obtained, for example, through substantially the same process as that for the phosphor powder of this embodiment. That is, in the manufacturing process of the phosphor powder of this embodiment, the core particles can be obtained in the same manner except that the core particles are not added in the mixing step. The composition (general formula) of the core particles is also preferably the same as that of the phosphor powder of this embodiment.

[0069] In the mixing step of this embodiment, the raw material mixed powder can be obtained, for example, by dry mixing the starting materials or by wet mixing the starting materials in an inert solvent that does not substantially react with the starting materials and then removing the solvent. Examples of mixing devices that can be used include a small mill mixer, a V-type mixer, a rocking mixer, a ball mill, and a vibration mill. After mixing using the device, aggregates can be removed using a sieve as needed to obtain the raw material mixed powder. To prevent deterioration of the starting materials and unintended oxygen contamination, the mixing step of this embodiment is preferably performed in a nitrogen atmosphere or in an environment with as little moisture (humidity) as possible.

[0070] (Firing Step) In the firing step of this embodiment, the raw material mixed powder obtained in the mixing step is fired to obtain a fired powder. The firing temperature in the firing step of this embodiment is preferably 1850°C or higher, more preferably 1900°C or higher, and preferably 2050°C or lower, more preferably 2000°C or lower, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. By setting the firing temperature at or above the lower limit, grain growth of the phosphor particles proceeds more effectively. Therefore, the performance balance between the reliability and fluorescent properties of the phosphor powder can be further improved. By setting the firing temperature at or below the upper limit, decomposition of the phosphor particles can be further suppressed. Therefore, the performance balance between the reliability and fluorescent properties of the phosphor powder can be further improved.

[0071] The heating and holding time in the firing step of this embodiment is preferably 5 hours or more, more preferably 7 hours or more, and preferably 15 hours or less, and even more preferably 10 hours or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. The pressure in the firing step of this embodiment is preferably 0.7 MPaG or more, more preferably 0.8 MPaG or more, and preferably 1 MPaG or less, and more preferably 0.9 MPaG or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. From the viewpoint of controlling the oxygen concentration, the firing step of this embodiment is preferably performed in a nitrogen gas atmosphere. That is, the firing step is preferably performed in a nitrogen gas atmosphere with a pressure of 0.7 MPaG or more and 1 MPaG or less.

[0072] In the firing process of this embodiment, in order to further improve the reliability of the phosphor powder and the performance balance of the fluorescent properties, it is preferable to heat the mixture in a container that is less likely to react with the raw material mixed powder during firing. Specifically, it is preferable to use a high-melting-point container, and more preferably a tungsten container. This can suppress the generation of heterogeneous phases.

[0073] Furthermore, in the firing process of this embodiment, the container is preferably a sealed container with high airtightness in order to further improve the reliability of the phosphor powder and the performance balance of its fluorescent properties. Firing the raw material mixed powder under sealed conditions can prevent oxygen and moisture (humidity) from entering the container and suppress deterioration of the raw material mixed powder, thereby further improving the reliability of the phosphor powder and the performance balance of its fluorescent properties. The sealed container preferably has a structure in which the interior of the container is sealed by narrowing the gap between the lid and the main body of the container. One method for narrowing the gap between the lid and the main body of the sealed container is, for example, to adopt a structure in which the main body and the lid of the container are fitted together, whereas conventional containers have a structure in which the lid is simply placed on the main body.

[0074] (Powdering step) In the powdering step of this embodiment, the fired powder is first powdered by using treatments such as crushing, pulverization, classification, etc. alone or in combination. Since the fired powder obtained through the firing step is usually a sintered mass, the fired powder is powdered to make it easier to handle.

[0075] A specific example of a method for the pulverization step of this embodiment is to pulverize the sintered body to a predetermined particle size using a general pulverizer such as a ball mill, a vibration mill, a jet mill, etc. However, care should be taken because excessive pulverization may produce fine particles that easily scatter light or may cause crystal defects on the particle surfaces, resulting in a decrease in luminous efficiency.

[0076] (Annealing Process) In the annealing process of this embodiment, after the pulverization process, the fired powder is annealed at a temperature lower than the firing temperature in the firing process to obtain an annealed powder. This can sufficiently improve the luminous efficiency of the phosphor powder. Furthermore, the rearrangement of elements removes distortions and defects, improving the reliability of the phosphor powder and the performance balance of its fluorescent properties. On the other hand, heterophases may occur during the annealing process. However, these can be sufficiently removed by the acid treatment process described below.

[0077] The annealing step of this embodiment is preferably carried out in a hydrogen gas atmosphere or an argon atmosphere, more preferably in an argon atmosphere, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder.

[0078] The pressure in the annealing step of this embodiment is preferably 0.7 MPaG or more, more preferably 0.8 MPaG or more, and preferably 1 MPaG or less, more preferably 0.9 MPaG or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. The heat treatment temperature in the annealing step of this embodiment is preferably 1250°C or more, more preferably 1300°C or more, and preferably 1450°C or less, more preferably 1400°C or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. The heat treatment time in the annealing step of this embodiment is preferably 5 hours or more, more preferably 7 hours or more, and preferably 10 hours or less, more preferably 9 hours or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder.

[0079] In the annealing step of this embodiment, similar to the firing step, it is preferable to fill the mixture into a container that is unlikely to react with the fired powder during heat treatment, such as a high-melting-point container, specifically a container with an inner wall made of tungsten, and heat it. Furthermore, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder, it is preferable that the container used in the annealing step is a sealed container as described above, and it is more preferable that both the containers used in the firing step and the annealing step are sealed containers.

[0080] (Acid Treatment Step) In the acid treatment step of this embodiment, the annealed powder obtained in the annealing step is subjected to an acid treatment to obtain an acid-treated powder. This allows at least a portion of the impurities that do not contribute to light emission to be removed. Incidentally, it is presumed that the impurities that do not contribute to light emission are generated during the firing step and the annealing step.

[0081] In the acid treatment step of this embodiment, an aqueous solution containing one or more acids selected from the group consisting of hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used as the acid. In particular, from the viewpoint of further improving the reliability of the phosphor powder and the performance balance of the fluorescent properties, the aqueous solution preferably contains hydrochloric acid, hydrofluoric acid, nitric acid, or a mixed acid of hydrofluoric acid and nitric acid, and more preferably contains hydrochloric acid.

[0082] The acid treatment step of this embodiment can be performed by dispersing the annealed powder in an aqueous solution containing the acid. The stirring time is preferably 30 minutes or more, more preferably 45 minutes or more, and preferably 3 hours or less, more preferably 2 hours or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder. The stirring temperature is preferably 50°C or more, more preferably 60°C or more, and preferably 100°C or less, more preferably 90°C or less, from the viewpoint of further improving the performance balance between the reliability and fluorescent properties of the phosphor powder.

[0083] After the acid treatment step of this embodiment, the liquid containing the dispersed annealed powder may be boiled, and substances other than the phosphor powder may be separated by filtration. If necessary, the substances adhering to the phosphor particles may be washed with water. After washing with water, the phosphor powder is usually dried by natural drying or drying in a dryer. The dried phosphor powder may be placed in a crucible and heated to modify the surface.

[0084] (Elutriation Step) In the elutriation step of this embodiment, after the acid treatment step, fine particles are removed from the acid-treated powder by elutriation. This makes it possible to remove fine particles that may deteriorate the fluorescent properties of the phosphor powder, thereby further improving the performance balance between the reliability and fluorescent properties of the phosphor powder.

[0085] The elutriation process involves adding the acid-treated powder to a dispersion medium, preparing a dispersion, stirring the mixture, allowing the acid-treated powder to settle, and then removing the supernatant. After removing the supernatant, the precipitate is collected by filtration and dried to obtain an acid-treated powder from which the fine particle powder has been removed. In the elutriation process, the preparation of the dispersion and the removal of the supernatant may be repeated. It is preferable to use an aqueous solution of sodium hexametaphosphate as the dispersion medium, in order to further improve the balance between the reliability and fluorescent properties of the phosphor powder.

[0086] (Atmospheric Heat Treatment Step) In the atmospheric heat treatment step of this embodiment, after the elutriation step, the acid-treated powder is subjected to atmospheric heat treatment to obtain atmospheric heat-treated powder. This improves the performance balance between the reliability and fluorescent properties of the phosphor powder. On the other hand, since excessive atmospheric heat treatment reduces the fluorescent properties of the phosphor powder, it is important to perform the atmospheric heat treatment under appropriate conditions to improve the performance balance between the reliability and fluorescent properties of the phosphor powder.

[0087] The atmospheric heat treatment step of this embodiment is preferably performed in air under atmospheric pressure in order to further improve the performance balance between the reliability and fluorescent properties of the phosphor powder. The heat treatment temperature in the atmospheric heat treatment step of this embodiment is preferably 250°C or higher, more preferably 280°C or higher, even more preferably 320°C or higher, even more preferably 350°C or higher, and even more preferably 380°C or higher, and is preferably 450°C or lower, more preferably 420°C or lower, in order to further improve the performance balance between the reliability and fluorescent properties of the phosphor powder. By setting the heat treatment temperature at or above the lower limit, the reliability of the phosphor powder can be further improved, and by setting the heat treatment temperature at or below the upper limit, the degradation of the fluorescent properties of the phosphor powder can be suppressed.

[0088] In order to further improve the performance balance between the reliability and fluorescent properties of the phosphor powder, the heat treatment time in the atmospheric heat treatment step of this embodiment is preferably 0.5 hours or more, more preferably 2 hours or more, and even more preferably 3.5 hours or more, and is preferably 6 hours or less, and more preferably 5 hours or less. By setting the heat treatment time to be equal to or greater than the lower limit, the reliability of the phosphor powder can be further improved, and by setting the heat treatment time to be equal to or less than the upper limit, the degradation of the fluorescent properties of the phosphor powder can be suppressed.

[0089] The temperature rise rate in the atmospheric heat treatment step of this embodiment is preferably 1°C / min or more, more preferably 2°C / min or more, and preferably 10°C / min or less, more preferably 5°C / min or less, and even more preferably 3°C / min or less, from the viewpoint of further improving the performance balance of the reliability and fluorescent properties of the phosphor powder.

[0090] <Composite> The composite of this embodiment includes, for example, the above-described phosphor powder and a sealant that seals the phosphor powder. In the composite of this embodiment, the above-described phosphor powder is dispersed in the sealant. From the viewpoint of further improving the reliability of the composite, the sealant of this embodiment preferably includes one or more materials selected from the group consisting of silicone resin, epoxy resin, urethane resin, glass, and ceramics.

[0091] In this embodiment, the content of the phosphor powder is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, when the total amount of the composite is taken as 100 mass%, from the viewpoint of further improving the reliability of the composite, and is preferably 20 mass% or less, more preferably 15 mass% or less, even more preferably 10 mass% or less, even more preferably 5 mass% or less.

[0092] In this embodiment, the content of the phosphor powder is preferably 0.1 mass % or more and 20 mass % or less, more preferably 0.1 mass % or more and 15 mass % or less, even more preferably 0.5 mass % or more and 10 mass % or less, and even more preferably 1 mass % or more and 5 mass % or less, from the viewpoint of further improving the reliability of the composite, when the total amount of the composite is taken as 100 mass %.

[0093] The composite of this embodiment can be produced by adding the phosphor powder of this embodiment to a liquid resin, glass, ceramics, etc., mixing the mixture uniformly, and then curing or sintering the mixture by heat treatment.

[0094] <Light-Emitting Device> The light-emitting device of this embodiment includes a light-emitting element that emits excitation light and a composite of this embodiment that converts the wavelength of the excitation light. Hereinafter, the light-emitting device of this embodiment will be described with reference to FIG. 1 , which is a schematic cross-sectional view showing an example of the structure of the light-emitting device of this embodiment. As shown in FIG. 1 , the light-emitting device 100 includes a light-emitting element 120, a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, bonding wires 170 and 172, and a composite 40.

[0095] The light emitting element 120 is mounted in a predetermined region on the upper surface of the heat sink 130. Mounting the light emitting element 120 on the heat sink 130 can improve the heat dissipation properties of the light emitting element 120. Note that a packaging substrate may be used instead of the heat sink 130.

[0096] The light-emitting element 120 is a semiconductor element that emits excitation light. For example, an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used as the light-emitting element 120. One electrode (not shown) disposed on the upper surface of the light-emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. The other electrode (not shown) formed on the upper surface of the light-emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.

[0097] A generally funnel-shaped recess whose diameter gradually increases from the bottom to the top is formed in the case 140. The light emitting element 120 is provided on the bottom of the recess. The wall of the recess surrounding the light emitting element 120 serves as a reflector.

[0098] The composite 40 is filled in the recess whose wall is formed by the case 140. The composite 40 is a wavelength conversion member that converts the excitation light emitted from the light-emitting element 120 into light with a longer wavelength. The composite 40 is the composite of this embodiment, and the phosphor powder 1 described above is dispersed in a sealing material 30 such as a resin. The light-emitting device 100 emits a mixed color of light from the light-emitting element 120 and light generated by the phosphor powder 1 that absorbs and is excited by the light from the light-emitting element 120. To obtain a white mixed color (to make the light-emitting device 100 a white LED), the composite 40 preferably contains, for example, LuAG phosphor powder in addition to the phosphor powder 1 (it is preferable that LuAG phosphor powder is dispersed in the sealing material 30 in addition to the phosphor powder 1). In this embodiment, the peak wavelength and half-width of the fluorescence spectrum of the phosphor powder 1 fall within certain numerical ranges, making it easy to obtain good white light.

[0099] 1 illustrates a surface-mounted light-emitting device, but the light-emitting device is not limited to the surface-mounted type. The light-emitting device may be a bullet type, a COB (chip-on-board) type, a CSP (chip-scale package) type, or the like.

[0100] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0101] The embodiments of the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited to the examples.

[0102] (Example 1) <Preparation of nucleating agent> First, 60.61 g of α-type silicon nitride (Si ３ N ４ , manufactured by Ube Industries, Ltd., SN-E10 grade), 53.13 g of aluminum nitride (AlN, manufactured by Tokuyama Corporation, E grade), and 13.68 g of europium oxide (Eu ２ O ３ , manufactured by Shin-Etsu Chemical Co., Ltd.) was added and premixed.

[0103] Next, in a glove box maintained in a nitrogen atmosphere in which the moisture content was adjusted to 1 mass ppm or less and the oxygen concentration was adjusted to 50 mass ppm or less, 5.76 g of calcium nitride (Ca ３ N ２ , manufactured by Materion), and 106.82 g of strontium nitride (Sr ３ N ２ (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 2N) was further added and dry mixed to obtain a mixture.

[0104] In a glove box, 240 g of the mixture was filled into a tungsten sealed container. After closing the lid of the sealed container, it was removed from the glove box and placed in an electric furnace equipped with a carbon heater. The electric furnace was then fully evacuated until the pressure inside was 0.1 PaG or less. Here, the sealed container has a structure in which the main body and the lid are fitted together, so the gap between the lid and the main body is narrower than in conventional containers, improving sealing performance.

[0105] While continuing the evacuation, the temperature inside the electric furnace was increased to 600°C. After reaching 600°C, nitrogen gas was introduced into the electric furnace, and the pressure inside the electric furnace was adjusted to 0.85 MPaG. Thereafter, under a nitrogen gas atmosphere, the temperature inside the electric furnace was increased to 1950°C, and after reaching 1950°C, heat treatment was carried out for 8 hours. Thereafter, heating was terminated, and the mixture was cooled to room temperature. After cooling to room temperature, red lumps were recovered from the container. The recovered lumps were crushed and sieved in a mortar to prepare core particles (nucleating agent) with a median diameter of 16 μm.

[0106] <Production of phosphor powder> 51.50 g of α-type silicon nitride (Si ３ N ４ , manufactured by Ube Industries, Ltd., SN-E10 grade), 45.14 g of aluminum nitride (AlN, manufactured by Tokuyama Corporation, E grade), 15.50 g of europium oxide (Eu ２ O ３ , manufactured by Shin-Etsu Chemical Co., Ltd.) and 24.00 g of the nucleating agent prepared as described above were weighed out and premixed.

[0107] Next, in a glove box maintained in a nitrogen atmosphere in which the moisture content was adjusted to 1 mass ppm or less and the oxygen concentration was adjusted to 50 mass ppm or less, 0.27 g of calcium nitride (Ca ３ N ２ , manufactured by Materion), and 103.58 g of strontium nitride (Sr ３ N ２ (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 2N) was further weighed and dry-mixed to obtain a mixed powder. Table 1 shows the relationship between the amounts of the nucleating agent and the raw material powder (mass %) and the breakdown of the amounts of each element (molar ratio) in the raw material powder.

[0108] In a glove box, 240 g of the mixed powder was filled into a sealed tungsten container. After closing the lid of the sealed container, it was removed from the glove box and placed in an electric furnace equipped with a carbon heater. Then, the electric furnace was evacuated sufficiently until the pressure inside the electric furnace became 0.1 PaG or less.

[0109] While continuing the vacuum evacuation, the temperature inside the electric furnace was raised to 600°C. After reaching 600°C, nitrogen gas was introduced into the electric furnace, and the pressure inside the electric furnace was adjusted to 0.85 MPaG. Thereafter, in a nitrogen gas atmosphere, the temperature inside the electric furnace was raised to 1950°C, and after reaching 1950°C, heat treatment was carried out for 8 hours. Thereafter, heating was terminated, and the mixture was allowed to cool to room temperature. After cooling to room temperature, red lumps were recovered from the container. The recovered lumps were crushed and sieved to adjust the particle size, and a fired powder was obtained.

[0110] The obtained sintered powder was filled into a sealed tungsten container and quickly transferred to an electric furnace equipped with a carbon heater. The furnace was thoroughly evacuated until the pressure inside the furnace was 0.1 PaG or less. Heating was started while continuing the evacuation, and when the temperature reached 600°C, argon gas was introduced into the furnace and the pressure inside the furnace was adjusted to atmospheric pressure. After the introduction of argon gas began, the temperature continued to rise to 1350°C. After the temperature reached 1350°C, the heat treatment was carried out for 8 hours. Then, heating was stopped and the mixture was cooled to room temperature. After cooling to room temperature, the annealed powder was recovered from the container. The recovered powder was passed through a sieve to adjust the particle size. In this way, annealed powder was obtained.

[0111] The obtained annealed powder was placed in 2.0 M hydrochloric acid at room temperature so that the slurry concentration was 25% by mass, and immersed for 1 hour at 70 to 80°C. This resulted in an acid treatment. After the acid treatment, the hydrochloric acid slurry was boiled for 1 hour while stirring. The boiled slurry was cooled to room temperature and filtered to separate the acid treatment solution from the solid content, yielding an acid-treated product. The acid-treated product was then dried in a dryer set at a temperature in the range of 100 to 120°C for 12 hours, yielding an acid-treated powder.

[0112] The obtained acid-treated powder was added to an aqueous solution of sodium hexametaphosphate to prepare a dispersion, which was then stirred. The acid-treated powder in the dispersion was then allowed to settle, and the supernatant was removed. After removing the supernatant, the precipitate was collected by filtration and dried to obtain an acid-treated powder from which the fine particle powder had been removed. The preparation of the dispersion and the removal of the supernatant were repeated five times.

[0113] The resulting acid-treated powder was then loaded into an alumina crucible and quickly transferred to an electric furnace equipped with a carbon heater, where it was heated at a rate of 2.5°C / min under atmospheric pressure and in an air atmosphere until the temperature reached 300°C. After the temperature reached 300°C, air heat treatment was carried out for 1 hour. The heating was then terminated, and the powder was cooled to room temperature, yielding an air-heat-treated powder. This resulted in the production of the phosphor powder of Example 1.

[0114] The obtained phosphor sample was subjected to powder X-ray diffraction using CuKα radiation using an X-ray diffractometer (Ultima IV manufactured by Rigaku Corporation). The obtained X-ray diffraction pattern was ３ The same diffraction pattern as that of the crystal was observed, and the main crystalline phase was CaAlSiN ３ It was confirmed that the crystal structure was identical to that of the crystal.

[0115] Example 2 A phosphor powder of Example 2 was obtained in the same manner as in Example 1, except that the atmospheric heat treatment temperature was set to 400°C.

[0116] Example 3 A phosphor powder of Example 3 was obtained in the same manner as in Example 1, except that the heat treatment in air was carried out for 4 hours.

[0117] Example 4 A phosphor powder of Example 4 was obtained in the same manner as in Example 1, except that the atmospheric heat treatment was carried out at a treatment temperature of 400° C. for a treatment time of 4 hours.

[0118] Comparative Example 1 A phosphor powder of Comparative Example 1 was obtained in the same manner as in Example 1, except that the atmospheric heat treatment was not carried out.

[0119] Comparative Example 2 A phosphor powder of Comparative Example 2 was obtained in the same manner as in Example 1, except that the atmospheric heat treatment temperature was set to 200°C.

[0120] Comparative Example 3 The phosphor powder of Comparative Example 3 was obtained in the same manner as in Example 1, except that a non-sealed tungsten container was used instead of a sealed tungsten container for firing and annealing. Here, the non-sealed container is a container having a structure in which a lid is simply placed on a main body.

[0121] <Oxygen content increase rate> Oxygen content rate X of phosphor powder １ The oxygen content (mass%) of the phosphor powder was determined by measuring 0.03 g of the phosphor powder using an oxygen / nitrogen analyzer (EMGA-920, manufactured by Horiba, Ltd.) and measuring the oxygen content using a pressure cooker tester (EHS-221M, manufactured by Espec Corp.) after 5 g of the phosphor powder was kept at 130°C, 98% relative humidity, and 0.16 MPaG for 53 hours.２ (mass%) to X １ From the above measurements, 100 x X ２ / X １ The increase rate (%) of the oxygen content of the phosphor powder before and after the pressure cooker test was calculated using the above method. The results are shown in Table 2.

[0122] <Composition> First, the phosphor powder was dissolved by pressure acid decomposition to prepare a sample solution. Next, the obtained sample solution was subjected to quantitative elemental analysis using an ICP optical emission spectrometer (Shimadzu Corporation, ICPE-9000) to measure the molar ratios of Eu, Sr, Ca, Al, and Si contained in the phosphor powder. The results are shown in Table 1. Furthermore, 0.03 g of the phosphor powder was weighed out, and the oxygen and nitrogen contents were measured using an oxygen / nitrogen analyzer to determine the molar ratios of N and O. The results are shown in Table 1.

[0123] <Median diameter> Using a Microtrac MT3300EX II (manufactured by Microtrac Bell), the particle size distribution of the phosphor powder was measured by a laser diffraction scattering method in accordance with JIS R1629:1997. Specifically, approximately 0.1 g of phosphor powder was added to 100 mL of ion-exchanged water, and a dispersion treatment was carried out for 3 minutes using an Ultrasonic Homogenizer US-150E (manufactured by Nippon Seiki Seisakusho, tip size φ20 mm, Amplitude 100%, oscillation frequency 19.5 kHz, amplitude approximately 31 μm), and then measurement was carried out using the MT3300EX II. From the obtained particle size distribution, the median diameter D of the phosphor powder was determined. ５０ The results are shown in Table 2.

[0124] <Fluorescence Spectrum> Fluorescence measurements were performed using a spectrofluorometer (Hitachi High-Technologies Corporation, F-7000) calibrated with rhodamine B and a secondary standard light source. Specifically, the phosphor powder was first filled into a concave cell so that the surface was smooth, and the cell was attached to the opening of an integrating sphere. Next, monochromatic light with a wavelength of 455 nm emitted from a Xe lamp, which serves as a light source, was introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. The phosphor powder was irradiated with this monochromatic excitation light, and the fluorescence spectrum was measured using the spectrophotometer.

[0125] <Peak wavelength, half width, relative fluorescence intensity> The obtained phosphor powder was irradiated with light having a wavelength of 455 nm, and the peak wavelength and half width of the peak of the fluorescence spectrum were determined from the fluorescence spectrum. In addition, the relative fluorescence intensity Y of the phosphor powder was calculated from the peak intensity. １ The results are shown in Table 2. Here, the relative fluorescence intensity Y １ The relative fluorescence intensity Y was calculated by setting the peak height of the emission spectrum obtained by irradiating YAG:Ce (P46Y3, manufactured by Kasei Optonix Co., Ltd.) with monochromatic light of 455 nm as 100%, and expressing the peak intensity of the fluorescence spectrum as a relative peak intensity (%). １ is a relative value to a standard sample.

[0126] <Absorptivity, Internal Quantum Efficiency, External Quantum Efficiency> The emission intensity of the phosphor powder was determined from the obtained fluorescence spectrum data, and the number of reflected excitation light photons (Qref) and the number of fluorescent photons (Qem) were calculated. The number of reflected excitation light photons was calculated in the wavelength range of 450 to 465 nm, and the number of fluorescent photons was calculated in the wavelength range of 465 to 800 nm. Using the same device, a standard reflector with a reflectivity of 99% (Spectralon®, manufactured by Labsphere) was attached to the opening of the integrating sphere to measure the spectrum of excitation light with a wavelength of 455 nm. The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm. From the above calculation results, the absorptivity Z1, internal quantum efficiency, and external quantum efficiency of the phosphor powder for 455 nm light were calculated using the following formula. The results are shown in Table 2. Absorption rate Z1 for 455 nm light = ((Qex - Qref) / Qex) x 100 Internal quantum efficiency = (Qem / (Qex - Qref)) x 100 External quantum efficiency = (Qem / Qex) x 100

[0127] <Relative Fluorescence Intensity Reduction Rate> Using a pressure cooker tester (EHS-221M, manufactured by Espec Corp.), 5 g of phosphor powder was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours, and then the relative fluorescence intensity Y ２ (%) is the above-mentioned Y １ From the above measurements, 100 × (Y１ -Y ２ ) / Y １ The relative fluorescence intensity reduction rate (%) of the phosphor powder before and after the pressure cooker test was calculated using the above method. The results are shown in Table 2.

[0128] <Absorbance Reduction Rate> Using a pressure cooker tester (EHS-221M, manufactured by Espec Corporation), 5 g of phosphor powder was kept in an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG for 53 hours, and then the absorptance Z of the phosphor powder for light of 455 nm was measured. ２ (%) is the above-mentioned Z １ From the above measurements, 100 × (Z １ -Z ２ ) / Z １ The reduction rate (%) of the absorptance of the phosphor powder before and after the pressure cooker test was calculated using the above method. The results are shown in Table 2.

[0129] The ratios of the raw materials used are shown in Table 1. In Table 1, the values ​​in the columns Eu (molar ratio), Sr (molar ratio), Ca (molar ratio), Al (molar ratio), Si (molar ratio), and b / (b+c) do not include the elements in the core particles.

[0130]

[0131]

[0132] The phosphor powders of Examples 1 to 4, in which the oxygen content increase rate was 100% or more and 500% or less, had a relative fluorescence intensity decrease rate of 3.7% or less and an absorptivity decrease rate of 1.6% or less. On the other hand, the phosphor powders of Comparative Examples 1 to 3, in which the oxygen content increase rate exceeded 500%, had a relative fluorescence intensity decrease rate of 10.5% or more and an absorptivity decrease rate of 5.2% or more. From this, it can be seen that the phosphor powders of Examples 1 to 4 had improved reliability compared to the phosphor powders of Comparative Examples 1 to 3.

[0133] This application claims priority based on Japanese Patent Application No. 2023-118509, filed on July 20, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0134] REFERENCE SIGNS LIST 1 Phosphor powder 30 Sealant 40 Composite 100 Light emitting device 120 Light emitting element 130 Heat sink 140 Case 150 First lead frame 160 Second lead frame 170 Bonding wire 172 Bonding wire

Claims

1. A phosphor powder containing one or more phosphor particles selected from the group consisting of CASN phosphor particles and SCASN phosphor particles, wherein the oxygen content increase rate of the phosphor powder is 100% or more and 500% or less by the following method 1. (Method 1) The oxygen content of the phosphor powder is X １ (mass %), and the oxygen content of the phosphor powder after 5 g of the phosphor powder was kept for 53 hours under an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG using a pressure cooker tester was X ２ (mass%), 100 x X ２ / X １ is the oxygen amount increase rate (%).

2. The above X １ The phosphor powder according to claim 1 , wherein the content of the phosphor powder is 0.10 mass % or more and 5.00 mass % or less.

3. General formula, Eu ａ Sr ｂ Ca ｃ A ｄ S ｅ N ｆ O ｇ 3. The phosphor powder according to claim 1, comprising phosphor particles represented by the formula: 0<a<1.00, 0<b<1.00, 0<c<1.00, 0.70<a+b+c<1.30, 0.70<d<1.30, 0.70<e<1.30, 0<f<3.00, 0<g<3.00, and 2.50<f+g<3.

50.

4. The phosphor powder according to claim 3, wherein a<0.

30.

5. The phosphor powder according to claim 3, wherein b>0.

50.

6. The phosphor powder according to claim 3, wherein the molar ratio b / (b+c) of said phosphor powder is 0.96 or more and 0.99 or less.

7. Volume-based median diameter D of the phosphor powder measured by laser diffraction scattering method ５０ The phosphor powder according to claim 1 or 2, wherein the particle size is 1 μm or more and 40 μm or less.

8. The phosphor powder according to claim 1 or 2, which has an internal quantum efficiency of 60.0% or more when excited by light having a wavelength of 455 nm.

9. The phosphor powder according to claim 1 or 2, which has an external quantum efficiency of 60.0% or more when excited by light having a wavelength of 455 nm.

10. The phosphor powder according to claim 1 or 2, wherein the reduction rate of the relative fluorescence intensity of the phosphor powder is 10.0% or less according to the following method 2. (Method 2) The relative fluorescence intensity of the phosphor powder measured using a spectrophotometer is set to Y １ (%), and the relative fluorescence intensity of the phosphor powder after 5 g of the phosphor powder was kept for 53 hours under an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG using a pressure cooker tester was measured. ２ (%), 100 x (Y １ -Y ２ ) / Y １ is the relative fluorescence intensity decrease rate (%).

11. The above Y １ The phosphor powder according to claim 10, wherein the luminance distribution is 150% or more.

12. The phosphor powder according to claim 1 or 2, wherein the absorptance reduction rate of the phosphor powder for light having a wavelength of 455 nm is 5.0% or less, according to the following method 3. (Method 3) The absorptance of the phosphor powder for light having a wavelength of 455 nm measured using a spectrophotometer is Z １ (%), and the absorptivity of the phosphor powder with respect to light having a wavelength of 455 nm after 53 hours of holding 5 g of the phosphor powder under an atmosphere of 130° C., 98% relative humidity, and 0.16 MPaG using a pressure cooker tester was determined as Z ２ (%), 100 x (Z １ -Z ２ ) / Z １ is the absorption rate reduction rate (%).

13. Said Z １ The phosphor powder according to claim 12, wherein the content is 90.0% or more.

14. A composite comprising the phosphor powder according to claim 1 or 2 and a sealing material that seals the phosphor powder.

15. The composite according to claim 14, wherein the sealing material comprises one or more materials selected from the group consisting of silicone resin, epoxy resin, urethane resin, glass and ceramics.

16. A light emitting device comprising: a light emitting element that emits excitation light; and the composite according to claim 14 that converts the wavelength of the excitation light.

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