Phosphor powder

Abstract

To provide a novel phosphor.SOLUTION: One aspect of the present invention relates to a phosphor powder, which includes phosphor particles having a host crystal represented by the general formula ASc6Si7O24 and an activating element Re that is substitutionally solid-solubilized in the host crystal. In the general formula, A represents at least one selected from the group consisting of Ca, Sr, and Ba, and Re represents at least one selected from the group consisting of Eu2+ and Ce3+.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to phosphor powders. [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 phosphors are 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 new phosphor. [Means for Solving the Problems]

[0007] The present disclosure provides the following [1] to [8].[[]END]]

[0008] [1] Phosphor particles comprising a host crystal represented by the general formula ASc6Si7O 24 and an activating element Re substitutionally solid-solved in the host crystal, wherein A represents at least one selected from the group consisting of Ca, Sr, and Ba, and Re represents at least one selected from the group consisting of Eu 2+ and Ce 3+ A phosphor powder. [2] General formula A 1-x Sc6Si7O 24 :Eu x , or general formula A 1-(3 / 2)x Sc6Si7O 24 :Ce x represented by wherein x is a numerical value satisfying 0 < x < 1, the phosphor powder according to [1].[[]END]] [3] The phosphor particles belong to the monoclinic system and are crystals having space group P21 / m symmetry, the phosphor powder according to [1] or [2].[[]END]] [4] The unit lattice volume calculated from the lattice constant of the phosphor powder measured by powder X-ray diffraction is 0.891±0.005 nm 3 The phosphor powder according to any one of [1] to [3], [5] The lattice constants a, b, and c of the phosphor powder measured by powder X-ray diffraction are respectively a = 0.53 ± 0.05 nm, b = 2.67 ± 0.05 nm, c = 0.65 ± 0.05 nm, The phosphor powder according to any one of [1] to [4], 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 shows the emission spectrum of the phosphor powder prepared in the example. 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 powder according to one embodiment of the present disclosure has the general formula ASc6Si7O 24It contains phosphor particles having a host crystal represented by and an activating element Re substitutionally solid-solved in the host crystal. From the viewpoint of exhibiting a more desirable emission spectrum, the phosphor powder may consist of the phosphor particles. Note that the host crystal has the general formula ASc6Si7O 24 and is a novel inorganic crystal that has not been reported so far. The above A may be an alkaline earth metal and may represent at least one selected from the group consisting of Ca, Sr, and Ba.

[0014] In the phosphor powder, the activating element Re may substitutionally solid-solve a part of the A element. That is, the phosphor powder may be represented by the general formula A 1-x Sc6Si7O 24 :Eu x or the general formula A 1-(3 / 2)x Sc6Si7O 24 :Ce x In this case, the above x may be a numerical value satisfying 0 < x < 1.

[0015] In the phosphor powder, the above Re may be at least one selected from the group consisting of Eu 2+ and Ce 3+ and is preferably Eu 2+ or Ce 3+

[0016] Among the constituent elements of the phosphor powder, A, Sc, Si, and Re (activating element), and the ratios of these elements can be determined by an ICP emission spectroscopic analysis method using a multi-type ICP emission spectroscopic analyzer. Among the constituent elements of the phosphor powder, O and its ratio can be determined using an oxygen and nitrogen analyzer. As the oxygen and nitrogen analyzer, "EMGA-920" (product name) manufactured by Horiba, Ltd. can be used. Note that since the elemental composition in the phosphor corresponds to the ratio of the charge of each element when manufacturing the phosphor, the elemental composition of the phosphor can also be estimated from the raw material composition.

[0017] ​The phosphor particles may belong to the monoclinic system and may be a crystal having space group P21 / m symmetry. The host crystal has the same symmetry as the phosphor particles and may belong to the monoclinic system and may be a crystal having space group P21 / m symmetry. The space group of the crystal corresponds to number 11 in the International Tables for Crystallography.

[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 powder may be prepared so that the lattice constants a, b, and c of the phosphor powder 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 phosphor powder measured by powder X-ray diffraction may be a=0.53±0.05 nm, b=2.67±0.05 nm, and c=0.65±0.05 nm, respectively.

[0020] In the phosphor powder, the unit lattice volume calculated from the lattice constant of the phosphor powder measured by powder X-ray diffraction is 0.891±0.005 nm 3 The upper limit of the unit lattice volume of the phosphor powder may be, for example, 0.895 nm 3 Below, 0.894nm 3 Below, 0.893nm 3 Less than or equal to 0.892 nm 3 The lower limit of the unit lattice volume of the phosphor powder may be, for example, 0.886 nm 3 Above, 0.888nm 3 or more than 0.889 nm 3 It may be more than that.

[0021] The emission peak wavelength of the phosphor powder depends on the amount of Re in solid solution, or, when Re is Eu, the amount of Eu in the solid solution. 2+The ratio of the phosphor powder to the total phosphor content can be adjusted by the ratio of the phosphor powder to the total phosphor content. The phosphor powder may have an emission peak in the wavelength range of 435 to 455 nm in the emission spectrum obtained when irradiated with light having a wavelength of 300 nm. In the emission spectrum obtained when irradiated with light having a wavelength of 300 nm, the emission peak wavelength having the maximum emission intensity of the phosphor powder belonging to the wavelength range of 435 to 455 nm can be, for example, 436 nm or more, 437 nm or more, 438 nm or more, or 440 nm or more. The emission peak wavelength having the maximum emission intensity of the phosphor powder can be, for example, 454 nm or less, 453 nm or less, 452 nm or less, or 450 nm or less.

[0022] In the phosphor powder, when Re is Eu, the half width of the emission peak having the maximum emission intensity in the wavelength region of 60 to 90 nm can be small in the emission spectrum obtained when irradiated with light having a wavelength of 300 nm. The upper limit of the half width of the emission peak may be, for example, 89 nm or less, 88 nm or less, or 87 nm or less. By setting the upper limit of the half width of the emission peak within the above range, the phosphor powder can have a higher emission intensity. The lower limit of the half width of the emission peak may be, for example, 61 nm or more, 62 nm or more, or 63 nm or more.

[0023] The emission peak wavelength of the phosphor powder depends on the amount of Re in solid solution, or, when Re is Ce, the proportion of Ce in the solid solution element. 3+ The ratio of the phosphor powder to the total phosphor content can be adjusted by the ratio of the phosphor powder to the total phosphor content. The phosphor powder may have an emission peak in the wavelength range of 385 to 405 nm in the emission spectrum obtained when irradiated with light having a wavelength of 360 nm. In the emission spectrum obtained when irradiated with light having a wavelength of 360 nm, the emission peak wavelength having the maximum emission intensity of the phosphor powder belonging to the wavelength range of 385 to 405 nm can be, for example, 386 nm or more, 387 nm or more, 388 nm or more, or 390 nm or more. The emission peak wavelength having the maximum emission intensity of the phosphor powder can be, for example, 405 nm or less, 403 nm or less, 402 nm or less, or 400 nm or less.

[0024] In the phosphor powder, when Re is Ce, the half width of the emission peak having the maximum emission intensity in the wavelength range of 45 to 75 nm can be small in the emission spectrum obtained when irradiated with light having a wavelength of 360 nm. The upper limit of the half width of the emission peak may be, for example, 74 nm or less, 73 nm or less, or 72 nm or less. By setting the upper limit of the half width of the emission peak within the above range, the phosphor powder can have a higher emission intensity. The lower limit of the half width of the emission peak may be, for example, 46 nm or more, 47 nm or more, or 48 nm or more.

[0025] In this specification, the wavelength and half-width of the emission peak of the phosphor powder refer to values ​​determined by measuring the emission spectrum when irradiated with light having a wavelength of 300 nm when Re is Eu, and refer to values ​​determined by measuring the emission spectrum when irradiated with light having a wavelength of 360 nm when Re is Ce. 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 the above-mentioned emission spectrum measurement.

[0026] An example of a method for producing a phosphor powder includes calcining a raw material mixture containing a compound having an alkaline earth metal as a constituent element, a scandium source, silicon dioxide, and at least one of a europium source and a cerium source under a reducing atmosphere to obtain a calcined product (hereinafter also referred to as the calcination process).

[0027] In the 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 desired phosphor particles.

[0028] In the raw material mixture, the compound having an alkaline earth metal as a constituent element, the scandium source, the silicon dioxide, the europium source, and the cerium source may each independently be a carbonate, a nitrate, an oxide, a hydroxide, or a chloride. The alkaline earth metal may be, for example, at least one selected from the group consisting of calcium, strontium, and barium, and may contain strontium or be strontium from the viewpoint of further improving the luminescence characteristics. The compound having an alkaline earth metal as a constituent element may be, for example, strontium carbonate, strontium oxide, strontium hydroxide, strontium chloride, and strontium nitrate. The scandium source may be, for example, scandium oxide (Sc2O3), scandium chloride, and scandium nitrate. The europium source may be, for example, europium oxide (e.g., Eu2O3), europium chloride, europium nitrate, and europium fluoride. The cerium source may be, for example, cerium oxide (CeO2), cerium chloride, and cerium nitrate.

[0029] The raw material mixture may contain other components in addition to the compound having an alkaline earth metal as a constituent element, the scandium source, silicon dioxide, the europium source, and the cerium source. Examples of the other components include compounds that melt and form a liquid phase at the heating temperature in the firing process or at a temperature lower than the heating temperature. 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 above-mentioned compounds that can function as fluxes may be, for example, inorganic compounds, and more specifically, magnesium fluoride and the like can be mentioned.

[0030] 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.

[0031] The heating temperature (firing temperature) in the firing step may be, for example, 1000 to 1600° C., 1200 to 1550° C., 1300 to 1500° C., or 1400 to 1500° 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.

[0032] 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.

[0033] The firing step is carried out in a reducing atmosphere. By carrying out the firing step in a reducing atmosphere, the activation element europium (Eu) or the like can be reduced and the valence of the element can be adjusted. More specifically, in the firing step, for example, 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.

[0034] The firing step may be performed under atmospheric pressure or under pressure. When the firing step is performed under a pressure environment, the lower limit of the firing pressure in the firing step may be, for example, 0.01 MPaG or more, or 0.02 MPaG or more. When the lower limit of the firing pressure is within the above range, the generation of a different phase can be more sufficiently suppressed. The upper limit of the firing pressure in the firing step may be, for example, 1.0 MPaG or less, 0.50 MPaG or less, 0.30 MPaG or less, or 0.10 MPaG or less. When the upper limit of the firing pressure is within the above range, the luminescence characteristics can be further improved. The pressure in the firing step can be adjusted within the above range, and may be, for example, 0.01 to 1.0 MPaG, or 0.02 to 0.10 MPaG.

[0035] Pressure in this specification means gauge pressure.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 portion 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 portion 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 contains the phosphor powder according to the present disclosure.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 blue phosphor, and a green phosphor (a green phosphor other than the phosphor according to the present disclosure), etc.

[0044] 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.

[0045] Although several embodiments have been described above, the present disclosure is not limited to the above-described embodiments. In addition, the descriptions of the above-described embodiments can be mutually applied. EXAMPLES

[0046] 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.

[0047] Example 1 Strontium carbonate (SrCO3, manufactured by Kojundo Chemical Laboratory Co., Ltd.) was 0.776 g, scandium oxide (Sc2O3, manufactured by HUNAN JINKUN NEW MATERIAL) was 1.098 g, silicon dioxide (SiO2, manufactured by Kojundo Chemical Laboratory Co., Ltd.) was 1.117 g, and europium oxide (Eu2O3, manufactured by Shin-Etsu Chemical Co., Ltd.) was 0.009 g. Each was weighed out and mixed in an alumina mortar in air for 10 minutes to obtain a raw material mixture.

[0048] Next, 3.00 g of the obtained raw material mixture was placed in an alumina crucible and placed in a carbon resistance furnace, where the temperature was raised from room temperature to 1450°C at a heating rate of 10°C / min and maintained at 1450°C for 8 hours. The atmosphere in the carbon resistance furnace was a nitrogen atmosphere at a pressure of 0.030 MPa. After that, it was cooled to room temperature and crushed in an alumina mortar to obtain a fired product. The obtained powder was Sr1-x Sc6Si7O 24 :EU x (x=0.01), where the activating element (solid solution element) is Eu.

[0049] (Examples 2 and 3) Powders were prepared in the same manner as in Example 1, except that the amount of Eu in solid solution was changed as shown in Table 1. 1-x Sc6Si7O 24 :EU x (x is 0.05 and 0.10, respectively).

[0050] Example 4 A powder was prepared in the same manner as in Example 1, except that 0.444 g of strontium carbonate (SrCO3, manufactured by Kojundo Chemical Laboratory Co., Ltd.), 1.265 g of scandium oxide (Sc2O3, manufactured by Hunan Jinkun New Materials Co., Ltd.), 1.286 g of silicon dioxide (SiO2, manufactured by Kojundo Chemical Laboratory Co., Ltd.), and 0.005 g of cerium oxide (CeO2, manufactured by Shin-Etsu Chemical Co., Ltd.) were weighed out and mixed in an alumina mortar in air for 10 minutes to obtain a raw material mixture. 1-(3 / 2)x Sc6Si7O 24 :Ce x (x is 0.01).

[0051] [Determination of lattice constants and unit cell volume] X-ray diffraction measurements were performed on the powders prepared in the examples using an X-ray diffractometer (Rigaku Corporation, product name: Ultima IV) to measure the lattice constants a, b, and c, as well as the axial angles α, β, and γ of the phosphor powders. The unit lattice volume was determined from the obtained values ​​of the lattice constants a, b, and c. The measurement range was 10 to 120°. The results are shown in Table 1.

[0052] [Determination of emission peak wavelength and half-width] The emission intensity of the powders prepared in the examples was measured to confirm whether they functioned as phosphors. Specifically, the phosphor powder was first filled into a dedicated solid sample holder. Then, using a fluorescence spectrophotometer, the emission spectrum was measured when the phosphor powder was irradiated with excitation light. The excitation light for the phosphor powders of Examples 1 to 3 was 300 nm, and the excitation light for the phosphor powder of Example 4 was 360 nm. A spectrofluorospectrophotometer "F-7000" (product name) manufactured by Hitachi High-Tech Science Corporation was used for the measurement. The results are shown in FIG. 2.

[0053] [Table 1] [Industrial Applicability]

[0054] According to the present disclosure, a novel phosphor can be provided. [Explanation of symbols]

[0055] 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. General formula ASc ６ S ７ O ２４ and an activation element Re substituted and solid-solved in the host crystal, The A represents at least one selected from the group consisting of Ca, Sr, and Ba, The Re is Eu ２＋ and Ce ３＋ A phosphor powder exhibiting at least one type selected from the group consisting of:

2. General formula A １－ｘ S.C. ６ S ７ O ２４ :Eu ｘ Or general formula A １－（３／２）ｘ S.C. ６ S ７ O ２４ : Ce ｘ It is expressed as The phosphor powder according to claim 1 , wherein the x is a value that satisfies 0<x<1.

3. The phosphor particles belong to the monoclinic system and the space group P2 １ 3. The phosphor powder according to claim 1, which is a crystal having n- / m symmetry.

4. The unit lattice volume calculated from the lattice constant of the phosphor powder measured by powder X-ray diffraction is 0.891±0.005 nm ３ The phosphor powder according to claim 1 or 2,

5. The lattice constants a, b, and c of the phosphor powder measured by powder X-ray diffraction are respectively a=0.53±0.05nm, b=2.67±0.05nm, c=0.65±0.05nm, The phosphor powder according to claim 1 or 2,

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