Phosphor

Abstract

To provide a novel phosphor.SOLUTION: One aspect of the present disclosure provides a phosphor comprising a host crystal having the same crystal structure as RbBaB7O12, and Eu2+ as an activator element. The phosphor preferably has an emission peak in a wavelength range of 435-455 nm in a fluorescence spectrum obtained upon irradiation with light having a wavelength of 266 nm. The phosphor may be represented by the general formula RbBa1-xB7O12:Eux (where x is a numerical value satisfying 0<x<1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to phosphors. [Background technology]

[0002] Phosphors are used in a variety of products, including vacuum fluorescent displays (VFDs), field emission displays (FRDs), surface-conduction electron-emitter displays (SECs), plasma display panels (PDPs), cathode-ray tubes (CRTs), liquid crystal display backlights, and light-emitting diodes (LEDs).

[0003] As phosphors, various phosphors are known, such as phosphors in which an activator element is solid-dissolved in nitrides such as β-SiAlON and CASN. In addition, Patent Document 1 discloses Na5Al3F 14 In contrast to Mn 4+ Patent Document 2 discloses a red phosphor containing Sr 6x (Si, Al) 27-12x (O,N) 31-6x Li 3y , where 0.4≦x≦0.8, 0≦y≦0.35, and Sr3Si 12.432 Al 8.568 O 1.608 N 26.392 Li 0.96 A phosphor containing an inorganic compound having a crystal having the same crystal structure as that of the above as a host crystal is disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-215451 [Patent Document 2] International Publication No. 2022 / 244523 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] With the expansion of the region where phosphors are used, various new phosphors are demanded from the viewpoint of expanding design options according to required characteristics such as high color reproducibility and heat resistance.

[0006] <000008​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​[7] The phosphor according to any one of [1] to [6], wherein the axial angles α, β, and γ in the unit cell of the host crystal measured by X-ray diffraction are α=90°, 112°≦β≦113°, and γ=90°, respectively. [8] The unit cell volume calculated from the lattice constant of the host crystal measured by X-ray diffraction is 1.042±0.005 nm 3 The phosphor according to any one of [1] to [7], wherein the range is: [Effects of the Invention]

[0008] According to the present disclosure, a novel phosphor can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device. [Figure 2] FIG. 2 shows the powder X-ray diffraction pattern of the phosphor prepared in Example 1 and a simulated powder X-ray diffraction pattern of RbBaB7O12. [Figure 3] FIG. 3 shows the excitation spectrum and fluorescence spectrum of the phosphor prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents.

[0011] Unless otherwise specified, the materials exemplified in this specification can be used singly or in combination of two or more.

[0012] The phosphor according to one embodiment of the present disclosure is RbBaB7O 12 The host crystal has the same crystal structure as the activator element Eu. 2+ The activator element may substitute for a part of the elements constituting the host crystal to form a solid solution. 1-x B7O 12:Eu x It may be represented by "[In the general formula, x is a numerical value satisfying 0 < x < 1]".

[0013] The constituent elements and ratios of the phosphor can be determined by an ICP emission spectroscopic analysis method using a multi-type ICP emission spectrometer. In addition, since the elemental composition in the phosphor corresponds to the charging ratio of each element when manufacturing the phosphor, the elemental composition of the phosphor can also be estimated from the raw material composition.

[0014] Whether the host crystal has the same crystal structure as RbBaB7O 12 can be confirmed by powder X-ray diffraction measurement. More specifically, in the diffraction pattern (a graph with the horizontal axis as the diffraction angle 2θ [unit: deg.(°)] and the vertical axis as the diffraction intensity [unit: arbitrary unit]) obtained by performing powder X-ray diffraction measurement on the host crystal to be measured, whether main peaks common to the simulation pattern of RbBaB7O 12 calculated from the crystal structure data of RbBaB7O 12 are observed can be judged.

[0015] The main peaks in the simulation pattern of the above RbBaB7O 12 are confirmed at 18.03°, 26.02°, 27.71°, and 29.94°. In the diffraction pattern exhibited by the host crystal of the phosphor to be measured, the target peaks to be compared with the main peak positions of the simulation pattern of the above RbBaB7O 12 may deviate by ±0.2° respectively from the main peak positions in the above simulation pattern. That is, RbBaB7O 12The diffraction pattern obtained by powder X-ray diffraction measurement of a host crystal having the same crystal structure as that of the phosphor has peaks within the ranges of 18.03±0.2°, 26.02±0.2°, 27.71±0.2°, and 29.94±0.2°. In powder X-ray diffraction measurement of a phosphor as the measurement object, peaks derived from the host crystal are also observed, so the measurement object may be a phosphor powder or a single particle contained in the powder.

[0016] The host crystal is RbBaB7O 12 The host crystal may be, for example, RbBaB7O 12 Examples include:

[0017] The host crystal may belong to the monoclinic system and may be a crystal having space group P21 / c symmetry.

[0018] In this specification, the space group of a crystal is determined by comparing the diffraction pattern of the X-ray diffraction spectrum of the sample to be measured with the diffraction pattern of a crystal group with a defined symmetry.

[0019] The phosphor may be prepared so that the lattice constants a, b, and c of the host crystal measured by powder X-ray diffraction are within a predetermined range. Here, the lattice constants a, b, and c refer to the a-axis length, b-axis length, and c-axis length of the host crystal, respectively. The lattice constants a, b, and c of the host crystal in the phosphor may be within the range of a = 1.06 ± 0.05 nm (i.e., 1.01 to 1.11 nm), b = 0.85 ± 0.05 nm (i.e., 0.80 to 0.90 nm), and c = 1.25 ± 0.05 nm (i.e., 1.20 to 1.30 nm), respectively.

[0020] The lattice constant a may be within the range of 1.06±0.03 nm (i.e., 1.03 to 1.09 nm) or within the range of 1.06±0.02 nm (i.e., 1.04 to 1.08 nm). The lattice constant b may be within the range of 0.85±0.03 nm (i.e., 0.82 to 0.88 nm) or within the range of 0.85±0.02 nm (i.e., 0.83 to 0.87 nm). The lattice constant c may be within the range of 1.25±0.03 nm (i.e., 1.22 to 1.28 nm) or within the range of 1.25±0.02 nm (i.e., 1.23 to 1.27 nm).

[0021] The phosphor may be prepared so that the axial angles α, β, and γ of the unit cell of the host crystal measured by powder X-ray diffraction are within predetermined ranges, where α=90°, β=112°≦β≦113°, and γ=90°, respectively.

[0022] In the phosphor, the unit lattice volume calculated from the lattice constant of the host crystal measured by powder X-ray diffraction is 1.042±0.005 nm 3 Within the range (i.e., 1.037-1.047 nm) 3 The unit cell volume of the phosphor may be, for example, 1.042±0.003 nm 3 Within the range (i.e., 1.039-1.045 nm) 3 ), or 1.042±0.002nm 3 Within the range (i.e., 1.040-1.044 nm) 3 ) may also be used.

[0023] The emission peak wavelength of the above phosphor depends on the amount of Eu in solid solution and the proportion of Eu in the solid solution element. 2+The ratio of the phosphor to the total phosphor may be adjusted by, for example, adjusting the ratio of the phosphor to the total phosphor content. The phosphor may have an emission peak in the wavelength range of 435 to 455 nm in the fluorescence spectrum obtained when irradiated with light having a wavelength of 266 nm. In the fluorescence spectrum obtained when irradiated with light having a wavelength of 266 nm, the emission peak wavelength showing the maximum emission intensity of the phosphor in the wavelength range of 435 to 455 nm can be, for example, 438 nm or more, 440 nm or more, 442 nm or more, or 444 nm or more. The emission peak wavelength showing the maximum emission intensity of the phosphor can be, for example, 452 nm or less, 450 nm or less, or 448 nm or less.

[0024] The phosphor can have a small half-width of an emission peak having a maximum emission intensity in the wavelength range of 435 to 455 nm in the fluorescence spectrum obtained when irradiated with light having a wavelength of 266 nm. The half-width of the emission peak may be, for example, less than 80 nm, less than 70 nm, less than 60 nm, or less than 50 nm. By setting the upper limit of the half-width of the emission peak within the above range, a phosphor with even more excellent emission intensity can be obtained. The lower limit of the half-width of the emission peak is not particularly limited, but the half-width of the emission peak may be, for example, 10 nm or more, or 20 nm or more.

[0025] In this specification, the wavelength and half-width of the emission peak of a phosphor refer to values ​​determined by measuring the fluorescence spectrum when irradiated with light having a wavelength of 266 nm. In this specification, the half-width refers to the full width at half maximum (FWHM) and can be determined from the fluorescence spectrum obtained by measuring the fluorescence spectrum when irradiated with light having a wavelength of 266 nm.

[0026] An example of a method for producing a phosphor includes firing a raw material mixture containing a rubidium source, a barium source, a boron source, and a europium source to obtain a first fired product (hereinafter also referred to as a "first firing step"), and firing the first fired product to obtain a second fired product (hereinafter also referred to as a "second firing step"). The second fired product may be a target phosphor.

[0027] In the first firing step, the raw material mixture is fired to react the raw material components and remove unnecessary components from the raw material components, thereby forming the basic crystal structure of the target phosphor.

[0028] In the raw material mixture, the rubidium source and the barium source may each independently be a carbonate or an oxide. Examples of the rubidium source include rubidium carbonate. Examples of the barium source include barium carbonate.

[0029] In the raw material mixture, the boron source may be a boron oxoacid, oxide, or the like. Examples of boron sources include boric acid and boron oxide. In the raw material mixture, the europium source may be a europium oxide, carbonate, nitrate, fluoride, oxyfluoride, chloride, or nitride, or a metal containing europium. Examples of europium sources include europium oxide, europium carbonate, europium nitrate, europium chloride, europium nitride, and europium (element).

[0030] The raw material mixture may contain other components in addition to the rubidium source, barium source, boron source, and europium source. Examples of other components include compounds that melt and form a liquid phase at or below the heating temperature in the first firing step. Such compounds function as fluxes, promoting the reaction of the raw material components and the grain growth of the phosphor particles, thereby producing a more stable phosphor. The compounds that can function as fluxes may be inorganic compounds, and more specifically, examples include magnesium fluoride.

[0031] The raw material mixture can be prepared by weighing and mixing each compound. A dry mixing method or a wet mixing method may be used for mixing. The dry mixing method may be, for example, a method in which each component is mixed using a V-type mixer or the like. The wet mixing method may be, for example, a method in which a solvent or dispersion medium such as water is added to prepare a solution or slurry, the components are mixed, and then the solvent or dispersion medium is removed.

[0032] The heating temperature (firing temperature) in the first firing step may be, for example, 500°C or higher, 550°C or higher, 600°C or higher, or 630°C or higher. When the firing temperature is equal to or higher than the lower limit, the formation of a crystalline structure can be further promoted. The firing temperature may be, for example, 1000°C or lower, 900°C or lower, 800°C or lower, 750°C or lower, or 700°C or lower. When the firing temperature is equal to or lower than the upper limit, the decomposition and volatilization of the raw material components can be further suppressed. The firing temperature may be, for example, 500 to 1000°C, or 550 to 750°C.

[0033] The heating time (firing time) in the first firing step may be, for example, 1 hour or more, 2 hours or more, 3 hours or more, 5 hours or more, or 6 hours or more. When the firing temperature is equal to or higher than the lower limit, the formation of a crystalline structure can be further promoted. The firing time may be, for example, 96 hours or less, 80 hours or less, 60 hours or less, 30 hours or less, 15 hours or less, 12 hours or less, or 10 hours or less. When the firing temperature is equal to or lower than the upper limit, the volatilization of raw material components can be further suppressed. The decomposition and volatilization of raw material components can be further suppressed. The firing time may be, for example, 1 to 96 hours or 1 to 12 hours.

[0034] The atmosphere in the first firing step (firing atmosphere) may contain, for example, air, nitrogen, hydrogen, argon, or a mixture of these gases. The firing atmosphere is preferably a reducing atmosphere. By using a reducing atmosphere, the valence of europium (Eu), which serves as an activating element, can be adjusted. More specifically, Eu 3+ EU 2+ Eu, which contributes to the desired luminescence 2+ The proportion of H2 can be increased. In order to adjust the degree of reduction of the reducing atmosphere, the reducing atmosphere may contain nitrogen or the like. The reducing atmosphere may be, for example, a mixed gas of nitrogen and hydrogen, or a mixed gas in which nitrogen and hydrogen are mixed at a volume ratio of N2:H2 = 96:4.

[0035] In the second firing step, the first fired product obtained in the first firing step is further fired to further promote the formation of the basic crystal structure of the target phosphor. As the first fired product, the first fired product obtained in the first firing step may be used as is, or, for example, the first fired product after being crushed through the crushing step described below may be used.

[0036] The heating temperature (firing temperature) in the second firing step may be, for example, 600°C or higher, 650°C or higher, 700°C or higher, or 730°C or higher. When the firing temperature is equal to or higher than the lower limit, the formation of a crystalline structure can be further promoted. The firing temperature may be, for example, 1000°C or lower, 950°C or lower, or 900°C or lower. When the firing temperature is equal to or lower than the upper limit, the decomposition and volatilization of the first fired product can be further suppressed. The firing temperature may be, for example, 600 to 1000°C, or 700 to 900°C.

[0037] The heating time (reduction time) in the second calcination step may be, for example, 1 hour or more, 2 hours or more, 3 hours or more, 5 hours or more, or 6 hours or more. By setting the calcination temperature at or above the lower limit, the formation of a crystalline structure can be further promoted. The calcination time may be, for example, 96 hours or less, 80 hours or less, 60 hours or less, 30 hours or less, 15 hours or less, 12 hours or less, or 10 hours or less. By setting the calcination temperature at or below the upper limit, the decomposition and volatilization of the first calcined product can be further suppressed. The calcination time may be, for example, 1 to 96 hours or 1 to 12 hours.

[0038] The atmosphere in the second firing step (firing atmosphere) may contain, for example, air, nitrogen, hydrogen, argon, or a mixture of these gases. The firing atmosphere is preferably a reducing atmosphere. By using a reducing atmosphere, the valence of europium (Eu), which serves as an activating element, can be adjusted. More specifically, Eu 3+ EU 2+ Eu, which contributes to the desired luminescence 2+The proportion of H2 can be increased. In order to adjust the degree of reduction of the reducing atmosphere, the reducing atmosphere may contain nitrogen or the like. The reducing atmosphere may be, for example, a mixed gas of nitrogen and hydrogen, or a mixed gas in which nitrogen and hydrogen are mixed at a volume ratio of N2:H2 = 96:4.

[0039] The above-mentioned manufacturing method includes two firing steps, a first firing step and a second firing step, but the number of firing steps is not limited to two. The number of firing steps may be three or more, or may be one. Another example of a method for manufacturing a phosphor includes firing a raw material mixture containing a rubidium source, a barium source, a boron source, and a europium source to obtain a fired product. The fired product may be the target phosphor. In this manufacturing method, the firing temperature, firing time, and firing atmosphere may be as described above for the firing temperature, firing time, and firing atmosphere in the second firing step, respectively.

[0040] The method for producing a phosphor may include other steps in addition to the firing steps (e.g., the first firing step and the second firing step), such as a crushing step and a classification step.

[0041] The crushing step is a step of crushing the fired products (for example, the first fired product and the second fired product) that may be obtained in a lump form after firing to adjust the particle size.

[0042] In the crushing step, a mortar or the like may be used, or a general crusher or disintegrator may also be used. Examples of crushers and disintegrators include a ball mill, a jet mill, and a Henschel mixer. The crushing step may be performed by wet ball milling in the presence of a medium such as ion-exchanged water. Zirconia balls may also be used in the ball mill.

[0043] An example of a light emitting device is a light emitting device including a light emitting element that emits primary light and a wavelength converter that absorbs a part of the primary light and emits secondary light having a wavelength longer than the wavelength of the primary light. The wavelength converter includes the phosphor described above. The light emitting element and the wavelength converter may be sealed with a sealing resin or the like.

[0044] FIG. 1 is a schematic cross-sectional view showing an example of a light-emitting device. The light-emitting device shown in FIG. 1 is an example of an optical semiconductor device classified as a surface-mount type. The light-emitting device 100 includes a substrate 10, a light-emitting element 40 electrically connected to a metal layer 20 provided on the surface of the substrate 10, a reflector 30 provided on the surface of the substrate 10 so as to surround the light-emitting element 40, and a transparent sealing resin 60 filled in a recess formed by the substrate 10 and the reflector 30 to seal the light-emitting element 40. A blue-emitting phosphor 52 and other phosphors 54 are dispersed in the transparent sealing resin 60. The blue-emitting phosphor 52 includes a phosphor according to the present disclosure.

[0045] The substrate 10 has a metal layer 20 formed on a portion of its surface, and the metal layer 20 serves as an electrode that is electrically connected to a light-emitting element 40 arranged on the surface of the substrate 10. The light-emitting element 40 is die-bonded to the metal layer 20 on either the anode side or the cathode side, and is electrically connected to the metal layer 20 via a die-bonding material 42. The light-emitting element 40 is electrically connected to the metal layer 20 on either the anode side or the cathode side via a bonding wire 44.

[0046] The reflecting section 30 is filled with a transparent sealing resin 60 for sealing the light-emitting element 40, and reflects the light (excitation light) emitted from the light-emitting element 40, as well as the fluorescence emitted from the blue-emitting phosphor 52 and other phosphors 54 in response to the light, towards the surface side of the light-emitting device 100.

[0047] The light-emitting element 40 may emit light (primary light, excitation light) that can excite the blue-emitting phosphor 52 and the other phosphors 54. The light-emitting element 40 may be, for example, a near-ultraviolet light-emitting diode (near-ultraviolet LED), an ultraviolet light-emitting diode (ultraviolet LED), or a blue light-emitting diode (blue LED). A plurality of light-emitting elements 40 may be provided.

[0048] The light emitting device 100 includes other phosphors 54 in addition to the blue-emitting phosphor 52, but may include only the blue-emitting phosphor 52. The other phosphors 54 may include, for example, a red phosphor, a yellow phosphor, a green phosphor, and a blue phosphor (other blue phosphors excluding the phosphor according to the present disclosure).

[0049] In the above example, the light emitting device has been described as an optical semiconductor device classified as a surface mount type, but the light emitting device is not limited to this. The light emitting device may be, for example, a light source for analysis, a signal device, or a light source for backlighting a liquid crystal display or liquid crystal panel.

[0050] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be applied to each other. [Example]

[0051] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0052] Example 1 Rubidium carbonate (Rb2CO3, manufactured by Sigma-Aldrich) was weighed out to 0.465 g, barium carbonate (BaCO3, manufactured by Kojundo Chemical Laboratory Co., Ltd.) to 0.786 g, boric acid (H3BO3, manufactured by Kojundo Chemical Laboratory Co., Ltd.) to 1.742 g, and europium oxide (Eu2O3, manufactured by Shin-Etsu Chemical Co., Ltd.) to 0.007 g, and these were mixed in an alumina mortar in air for 10 minutes to obtain a raw material mixture.

[0053] Next, 3.0 g of the resulting raw material mixture was placed in an alumina crucible, placed in a vertical furnace, and heated from room temperature to 650°C at a rate of 10°C / min, and held at 650°C for 8 hours. The atmosphere in the vertical furnace was a mixed gas of nitrogen and hydrogen (mixed so that the volume ratio of N2:H2 was 96:4). After that, it was cooled to room temperature, and the resulting first fired product was crushed in an alumina mortar to obtain a crushed first fired product.

[0054] Next, 1.9 g of the crushed first fired product was placed in an alumina crucible and placed in a vertical furnace. The temperature was raised from room temperature to 800°C at a rate of 10°C / min and maintained at 800°C for 8 hours. The atmosphere inside the vertical furnace was a mixed gas of nitrogen and hydrogen (mixed so that the volume ratio of N2:H2 was 96:4). After that, it was cooled to room temperature, and the obtained second fired product was crushed in an alumina mortar to obtain RbBa2O3 in which Eu was solid-dissolved. 1-x B7O 12 A powder of the formula was prepared.

[0055] [Confirmation of crystal structure] The crystal structure of the powder prepared in Example 1 was confirmed. First, an X-ray diffraction spectrum of the powder obtained in Example 1 was obtained. The obtained diffraction pattern was analyzed as follows: RbBaB7O 12 By comparing the simulation pattern with that of Example 1, it can be seen that the powder obtained in Example 1 is RbBaB7O 12 It was confirmed that the powder had the same crystal structure as that of RbBaB7O. For the measurement, an "Ultima IV" (product name) manufactured by Rigaku Corporation was used, and the measurement range was 10 to 60°. For reference, the X-ray diffraction pattern of the powder prepared in Example 1 (powder of Example 1) is shown in Figure 2. Figure 2 shows the X-ray diffraction pattern of RbBaB7O 12 The simulation pattern of RbBaB7O is also shown. 12 The simulation pattern was calculated from the crystal structure data described in Inorg. Chem. 2018, 57, 13380-13385.

[0056] [Determination of lattice parameters and unit cell volume] The powder prepared in Example 1 was analyzed by powder X-ray diffraction to determine the parent crystal (RbBaB7O 12 The lattice constants a, b, and c, as well as α, β, and γ of the crystal (having the same crystal structure as that of the compound 1) were measured. Specifically, these were determined by Rietveld analysis of the X-ray diffraction results. The unit cell volume was determined from the obtained values ​​of the lattice constants a, b, and c, as well as α, β, and γ. The results are shown in Table 1. Table 1 also shows the literature values ​​(adjusted for the number of digits) from Inorg. Chem. 2018, 57, 13380-13385.

[0057] [Determination of emission peak wavelength and half-width] The fluorescence spectrum of the powder prepared in Example 1 was measured to confirm its function as a phosphor. First, the powder to be measured was filled into a quartz cell, which was then fixed to the attached fixed sample holder. The excitation spectrum and fluorescence spectrum were measured. The fluorescence monitor wavelength was set to 445 nm when measuring the excitation spectrum. Light with a wavelength of 266 nm was used as excitation light when measuring the fluorescence spectrum. Furthermore, the wavelength at which the emission intensity was maximized in the obtained fluorescence spectrum was determined as the emission peak wavelength. Two wavelengths at which the emission intensity was half the maximum intensity at the emission peak wavelength were determined, and the half-width was calculated by taking the difference between these wavelengths. A spectrofluorometer "F-7000" (product name) manufactured by Hitachi High-Tech Science Corporation was used for the measurement. The results are shown in Table 1. For reference, the excitation spectrum and fluorescence spectrum of the powder prepared in Example 1 are shown in Figure 3.

[0058] [Table 1] [Explanation of symbols]

[0059] 10...base material, 20...metal layer, 30...reflective portion, 40...light-emitting element, 42...die bond material, 44...bonding wire, 52...blue-emitting phosphor, 54...other phosphor, 60...transparent sealing resin, 100...light-emitting device

Claims

1. RbBaB ７ O １２ A host crystal having the same crystal structure as Eu as an activator element ２＋ and a phosphor having

2. 2. The phosphor according to claim 1, which has an emission peak in the wavelength range of 435 to 455 nm in a fluorescence spectrum obtained when irradiated with light having a wavelength of 266 nm.

3. 3. The phosphor according to claim 2, wherein the half-value width of the emission peak is less than 50 nm.

4. General formula RbBa １－ｘ B ７ O １２ :Eu ｘ 4. The phosphor according to claim 1, wherein x is a number satisfying the general formula: 0<x<1.

5. The host crystal belongs to the monoclinic system and the space group P2 １ 4. The phosphor according to claim 1, which is a crystal having π / c symmetry.

6. The lattice constants a, b, and c of the host crystal measured by X-ray diffraction are respectively a = in the range of 1.06 ± 0.05 nm; b = in the range of 0.85 ± 0.05 nm; c = in the range of 1.25 ± 0.05 nm; The phosphor according to any one of claims 1 to 3, wherein

7. The axial angles α, β, and γ in the unit cell of the host crystal measured by X-ray diffraction are: each, α＝９０°、 １１２°≦β≦１１３°、 γ=90°, The phosphor according to any one of claims 1 to 3, wherein

8. The unit cell volume calculated from the lattice constant of the host crystal measured by X-ray diffraction is 1.042±0.005 nm ３ The phosphor according to any one of claims 1 to 3, wherein the range is:

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