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 NaBa3YSi6O20; and an activator element Eu2+. The phosphor may be represented by the general formula: NaBa3-xMSi6O20:Eux, where M is at least one of Y and Gd, and x is a numerical value satisfying 0<x<3.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Phosphors are used in a variety of products, such as vacuum-fluorescent displays (VFDs), field emission displays (FRDs), surface-conduction electron-emitter displays (SEMs), 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 dissolved in a nitride such as β-SiAlON or CASN. In addition, Patent Document 1 discloses Na5Al3F 14 For 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 as a host crystal a crystal having the same crystal structure as that of the above-mentioned compound 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 the phosphor is used, various new phosphors are demanded from the viewpoint of expanding the design options according to the required characteristics such as high color reproducibility and heat resistance.

[0006] The present disclosure aims to provide a novel phosphor. [Means for Solving the Problems]

[0007] The present disclosure provides the following [1] to [7].

[0008] [1] A host crystal having the same crystal structure as NaBa3YSi6O 20 and Eu as an activating element 2+ and, a phosphor. [2] The phosphor according to [1], which has an emission peak in the wavelength range of 440 to 460 nm in the fluorescence spectrum obtained when irradiated with light having a wavelength of 350 nm. [3] The phosphor according to [2], wherein the full width at half maximum of the emission peak is less than 85 nm. [4] A phosphor represented by the general formula NaBa 3-x MSi6O 20 :Eu x [In the general formula, M is at least one of Y and Gd, and x is a numerical value satisfying 0 < x < 3], which is described in any one of [1] to [3]. [5] The phosphor according to any one of [1] to [4], wherein the host crystal belongs to the orthorhombic system and has a crystal symmetry of space group Am2(40). [6] The unit cell volume calculated from the lattice constants of the host crystal measured by powder X-ray diffraction is 1.6 to 2.2 nm 3The phosphor according to any one of [1] to [5], [7] The lattice constants a, b, and c of the host crystal measured by powder X-ray diffraction are, respectively: a = 1.47 ± 0.05 nm, b = 2.38 ± 0.05 nm, c=0.55±0.05 nm, The phosphor according to any one of [1] to [6], Effect of the Invention

[0009] According to the present disclosure, a novel phosphor can be provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device. [Diagram 2] FIG. 2 is an X-ray diffraction spectrum of the phosphor powder prepared in Example 1. [Diagram 3] FIG. 3 shows the emission spectrum of the phosphor powder prepared in Example 1. [Figure 4] FIG. 4 is an X-ray diffraction spectrum of the phosphor powder prepared in Example 2. [Diagram 5] FIG. 5 shows the emission spectrum of the phosphor powder prepared in Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0013] The phosphor according to an embodiment of the present disclosure is NaBa3YSi6O 20 and a host crystal having the same crystal structure as that of 20 , and Eu as an activating element 2+ . The activating element may be substitutionally solid-solved in part of the elements constituting the host crystal. The phosphor has a general formula NaBa 3-x MSi6O 20 :Eu x [In the general formula, M is at least one of Y and Gd, and x is a numerical value satisfying 0 < x < 3].

[0014] 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. Note that since the elemental composition of 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.

[0015] Whether the host crystal has the same crystal structure as that of NaBa3YSi6O 20 can be confirmed by performing powder X-ray diffraction measurement. More specifically, in the diffraction pattern (a graph with the horizontal axis being the diffraction angle 2θ [unit: °] and the vertical axis being the diffraction intensity [unit: CPS]) obtained by performing powder X-ray diffraction measurement on the host crystal to be measured, it can be determined by whether the main peaks are observed in the diffraction pattern obtained by performing powder X-ray diffraction measurement of NaBa3YSi6O 20 . The main peaks in the diffraction pattern obtained by powder X-ray diffraction measurement of NaBa3YSi6O 20 are confirmed at 25.5°, 26.8°, 27.7°, and 29.1°. Note that 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 diffraction pattern of NaBa3YSi6O 20 may deviate by ±0.2° from the above main peak positions respectively. That is, NaBa3YSi6O 20The diffraction pattern obtained by powder X-ray diffraction measurement of a host crystal having the same crystal structure as that of has peaks at 25.5±0.2°, 26.8±0.2°, 27.7±0.2°, and 29.1±0.2°. In powder X-ray diffraction measurement in which a phosphor is used 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 NaBa3YSi6O 20 The host crystal may be, for example, NaBa3YSi6O 20 , and NaBa3GdSi6O 20 etc.

[0017] The host crystal may belong to the orthorhombic crystal system and may be a crystal having space group Am2(40) symmetry.

[0018] In this specification, the space group of a crystal is determined by comparing the diffraction pattern of the X-ray diffraction spectrum for 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 a=1.47±0.05 nm, b=2.38±0.05 nm, and c=0.55±0.05 nm, respectively.

[0020] In the phosphor, the unit lattice volume calculated from the lattice constant of the host crystal measured by powder X-ray diffraction is 1.6 to 2.2 nm 3 The unit cell volume of the phosphor may be, for example, 1.7 nm 3 Above, 1.8nm 3 or more, or 1.9 nm 3The unit cell volume of the phosphor may be, for example, 2.15 nm 3 Below, 2.1nm 3 Less than or equal to 2.05 nm 3 It may be the following:

[0021] 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. In the fluorescence spectrum obtained when irradiated with light having a wavelength of 350 nm, the phosphor may have an emission peak in the wavelength range of 440 to 460 nm. In the fluorescence spectrum obtained when irradiated with light having a wavelength of 350 nm, the emission peak wavelength having the maximum emission intensity of the phosphor belonging to the wavelength range of 440 to 460 nm may be, for example, 440 nm or more, 443 nm or more, 447 nm or more, or 450 nm or more. The emission peak wavelength having the maximum emission intensity of the phosphor may be, for example, 460 nm or less, 458 nm or less, 457 nm or less, or 456 nm or less.

[0022] The phosphor can have a small half-width of an emission peak having a maximum emission intensity in a wavelength range of 440 to 460 nm in a fluorescence spectrum obtained when irradiated with light having a wavelength of 350 nm. The upper limit of the half-width of the emission peak may be, for example, less than 85 nm, 80 nm or less, 75 nm or less, or 70 nm or less. By setting the upper limit of the half-width of the emission peak within the above range, a phosphor having a higher emission intensity can be obtained. The lower limit of the half-width of the emission peak is not particularly limited, but may be, for example, 30 nm or more, or 40 nm or more.

[0023] In this specification, the wavelength and half-width of the emission peak of the phosphor refer to values ​​determined by measuring the emission spectrum when irradiated with light having a wavelength of 350 nm. In this specification, the half-width refers to the full width at half maximum (FWHM) and can be determined from the emission spectrum obtained by measuring the emission spectrum when irradiated with light having a wavelength of 350 nm.

[0024] An example of a method for producing a phosphor includes calcining a raw material mixture containing at least one of an yttrium source and a gadolinium source, a sodium source, silicon dioxide, and europium oxide to obtain a calcined product (hereinafter also referred to as a calcination step), and heat-treating the calcined product in a reducing atmosphere to obtain a heat-treated product (hereinafter also referred to as a reduction step). The heat-treated product may be a target phosphor. In the following description of this example, the calcination step and the reduction step are described as separate steps, but for example, the calcination step may be performed in a reducing atmosphere, and in this case, performing an independent calcination step may be optional, or only the reduction step may be performed.

[0025] In the firing step, the raw material mixture is fired to react the raw material components and to remove unnecessary components from the raw material components, thereby forming the basic crystal structure of the desired phosphor.

[0026] In the raw material mixture, the yttrium source, the gadolinium source, and the sodium source may each independently be a carbonate or an oxide. The yttrium source may be, for example, yttrium oxide, etc. The gadolinium source may be, for example, gadolinium oxide, etc. The sodium source may be, for example, sodium carbonate, etc.

[0027] The raw material mixture may contain other components in addition to at least one of an yttrium source and a gadolinium source, a sodium source, silicon dioxide, and europium oxide. Examples of other components include compounds that melt and form a liquid phase at or below the heating temperature in the firing process. Such compounds function as fluxes, and can promote 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, magnesium fluoride and the like can be mentioned.

[0028] 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 of mixing each component using a V-type mixer or the like. The wet mixing method may be, for example, a method of adding a solvent or dispersion medium such as water to prepare a solution or slurry, mixing each component, and then removing the solvent or dispersion medium.

[0029] The heating temperature (firing temperature) in the firing step may be, for example, 800 to 1300° C., 900 to 1250° C., 1100 to 1250° C., or 1150 to 1200° C. When the lower limit of the firing temperature is within the above range, the reaction can be further promoted. Also, when the upper limit of the firing temperature is within the above range, the decomposition and volatilization of the raw material components can be further suppressed.

[0030] The heating time (calcination time) in the calcination step may be, for example, 1 to 96 hours, 1 to 80 hours, 1 to 60 hours, 1 to 30 hours, 2 to 15 hours, 2 to 12 hours, 2 to 10 hours, 3 to 10 hours, 5 to 10 hours, or 6 to 9 hours. When the lower limit of the calcination time is within the above range, the reaction can be further promoted. When the upper limit of the calcination time is within the above range, the volatilization of the raw material components can be further suppressed.

[0031] The atmosphere in the firing step (firing atmosphere) may contain, for example, air, nitrogen, hydrogen, argon, or a mixed gas thereof. The firing atmosphere may be air because it simplifies the production operation.

[0032] The reduction step is carried out in a reducing atmosphere. By carrying out the reduction step in a reducing atmosphere, europium (Eu), which is an activation element, can be reduced and the valence of the element can be adjusted. More specifically, in the reduction step, Eu 3+ EU 2+ Eu, which contributes to the desired light emission. 2+The ratio of can be increased. In order to adjust the degree of reduction of the reducing atmosphere, the reducing atmosphere may further contain nitrogen, etc. 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.

[0033] The heating temperature (reduction temperature) in the reduction step may be, for example, 800 to 1300° C., 900 to 1300° C., 1000 to 1300° C., or 1100 to 1200° C. When the lower limit of the reduction temperature is within the above range, the reduction efficiency can be improved. Also, when the upper limit of the reduction temperature is within the above range, the decomposition of the fired material can be more sufficiently suppressed.

[0034] The heating time (reduction time) in the reduction step may be, for example, 2 to 15 hours, 4 to 12 hours, 6 to 10 hours, or 7 to 9 hours. When the lower limit of the reduction time is within the above range, the reduction of the activation element can be more sufficient. When the upper limit of the reduction time is within the above range, the decomposition of the fired product can be more sufficiently suppressed.

[0035] The above-mentioned production method may include other steps in addition to the calcination step and the reduction step, such as a crushing step and a classification step.

[0036] The crushing step is a step of crushing the fired product obtained in the firing step and the heat-treated product obtained in the reduction step, which may be obtained in a lump form, and adjusting the particle size. In the crushing step, a mortar or the like may be used, or a general crusher or crusher may be used. Examples of the crusher and crusher include a ball mill, a jet mill, and a Henschel mixer. The crushing step is preferably performed by ball milling in a wet manner in the presence of a medium such as ion-exchanged water. Zirconia balls may be used in the ball mill.

[0037] An example of the 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 that 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.

[0038] 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 base material 10, a light emitting element 40 electrically connected to a metal layer 20 provided on the surface of the base material 10, a reflecting section 30 provided on the surface of the base material 10 so as to surround the light emitting element 40, and a transparent sealing resin 60 that fills a recess formed by the base material 10 and the reflecting section 30 and seals the light emitting element 40. A blue light emitting phosphor 52 and other phosphors 54 are dispersed in the transparent sealing resin 60. The blue light emitting phosphor 52 includes the phosphor according to the present disclosure.

[0039] The base material 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 base material 10. The light-emitting element 40 is die-bonded to either the metal layer 20 on 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 either the metal layer 20 on the anode side or the cathode side via a bonding wire 44.

[0040] 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 front side of the light-emitting device 100.

[0041] The light-emitting element 40 may emit light (primary light, excitation light) capable of exciting the blue-emitting phosphor 52 and 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), a blue light-emitting diode (blue LED), or the like. A plurality of light-emitting elements 40 may be provided.

[0042] 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), etc.

[0043] In the above example, the light emitting device is 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.

[0044] Although several embodiments have been described above, the present disclosure is not limited to the above-described embodiments. In addition, the contents of the descriptions of the above-described embodiments can be mutually applied. EXAMPLES

[0045] The present disclosure will be described in more detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the following examples.

[0046] Example 1 The following amounts were measured out and mixed in an alumina mortar in air for 10 minutes to obtain a raw material mixture: 0.20 g of sodium carbonate (Na2CO3, manufactured by Kanto Chemical Co., Ltd.), 2.18 g of barium carbonate (BaCO3, manufactured by Kojundo Chemical Laboratory Co., Ltd.), 1.26 g of yttrium oxide (Y2O3, manufactured by Kojundo Chemical Laboratory Co., Ltd.), 1.34 g of silicon dioxide (SiO2, manufactured by Kojundo Chemical Laboratory Co., Ltd.), and 0.02 g of europium oxide (Eu2O3, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0047] Next, 5 g of the obtained raw material mixture was placed in an alumina crucible, placed in a vertical furnace, and heated from room temperature to 1200°C at a heating rate of 10°C / min, and held at 1200°C for 8 hours. The atmosphere in the vertical furnace was kept at atmospheric composition. After that, it was cooled to room temperature and crushed in an alumina mortar to obtain a fired product.

[0048] 4 g of the fired product obtained as described above was placed in an alumina crucible, and heated in a high-temperature atmosphere furnace from room temperature to 1200°C at a heating rate of 5°C / min, and held at 1200°C for 8 hours. The atmosphere in the high-temperature atmosphere 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 crushed in an alumina mortar to obtain NaBa2CO3 with Eu as a solid solution. 3-x YSiO 20 :EU x A powder of the formula was prepared.

[0049] Example 2 General formula NaBa 3-x MSi6O 20 :EU x The same procedure as in Example 1 was repeated except that M in (x=0.01) was changed to Gd and the amount of each component was adjusted. 3-x GdSiO 20 :EU x A powder with a gadolinium content of 0.01 (x=0.01) was prepared. Gadolinium oxide (Gd2O3, Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the gadolinium source.

[0050] Example 3 The same procedure as in Example 1 was used to prepare NaBa2O3 with Eu as a solid solution, except that the firing temperature was changed to 800°C. 3-x YSiO 20 :EU x A powder with (x=0.01) was prepared.

[0051] [Confirmation of crystal structure] The crystal structure of the powder prepared in the examples was confirmed. First, the X-ray diffraction spectrum obtained in the examples was obtained. The obtained diffraction pattern was 20 By comparing with the X-ray diffraction pattern of NaBa3YSi6O 20 It was confirmed that the powder had the same crystal structure as that of NaBa3YSi6O. For the measurement, "Ultima IV" (product name) manufactured by Rigaku Corporation was used, and the measurement range was 10 to 60°. For reference, the X-ray spectra of the powders prepared in Examples 1 and 2 are shown in Figures 2 and 4, respectively. 20 The X-ray diffraction pattern is also shown.

[0052] [Determination of lattice constants and unit cell volume] For the powders prepared in the examples, the lattice constants a, b, and c of the host crystals were measured by powder X-ray diffraction. Specifically, the results of X-ray diffraction were obtained by Rietveld analysis. The unit cell volume was determined from the obtained values ​​of the lattice constants a, b, and c. The results are shown in Table 1.

[0053] [Determination of emission peak wavelength and half-width] The emission intensity of the powder prepared in the examples was measured to confirm whether it functions as a phosphor. First, the phosphor to be measured was filled in a quartz cell, which was then fixed to the attached fixed sample holder. Next, the emission spectrum was measured using light with a wavelength of 350 nm as the excitation light. When measuring the excitation spectrum, the fluorescence monitor wavelength was set to 454 nm to measure the excitation spectrum. In addition, in the obtained emission spectrum, the emission peak wavelength was determined, and the wavelength at which the intensity was half the maximum emission intensity of the emission peak was determined, and the half-width was calculated by taking the difference. For the measurement, a spectrofluorometer "F-7000" (product name) manufactured by Hitachi High-Tech Science Corporation was used. The results are shown in Table 1. For reference, the emission spectra of the powders prepared in Examples 1 and 2 are shown in Figures 3 and 5, respectively.

[0054] [Table 1] [Industrial Applicability]

[0055] According to the present disclosure, a novel phosphor can be provided, which can contribute to expanding design options as the fields in which phosphors are used expand. [Explanation of symbols]

[0056] 10...base material, 20...metal layer, 30...reflective portion, 40...light emitting element, 42...die bond material, 44...bonding wire, 52...blue light emitting phosphor, 54...other phosphors, 60...transparent sealing resin, 100...light emitting device.

Claims

1. NaBa ３ YSi ６ O ２０ A host crystal having the same crystal structure as Eu as an activator element ２＋ and a phosphor having the above structure.

2. 2. The phosphor according to claim 1, which has an emission peak in the wavelength range of 440 to 460 nm in a fluorescence spectrum obtained when irradiated with light having a wavelength of 350 nm.

3. The phosphor according to claim 2 , wherein the half-width of the emission peak is less than 85 nm.

4. General formula NaBa ３－ｘ MSi ６ O ２０ :Eu ｘ 3. The phosphor according to claim 1, represented by the general formula: [in which M is at least one of Y and Gd, and x is a number satisfying 0<x<3].

5. 3. The phosphor according to claim 1, wherein the host crystal is a crystal belonging to an orthorhombic crystal system and having space group Am2(40) symmetry.

6. The unit lattice volume calculated from the lattice constant of the host crystal measured by powder X-ray diffraction is 1.6 to 2.2 nm ３ The phosphor according to claim 1 or 2,

7. The lattice constants a, b, and c of the host crystal measured by powder X-ray diffraction are respectively a=1.47±0.05nm, b=2.38±0.05nm, c=0.55±0.05nm, The phosphor according to claim 1 or 2,

Images