Fluoride phosphor and light emitting device

Abstract

A high-brightness fluoride phosphor is provided. The fluoride phosphor has the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M contains at least one selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, the molar number of fluorine atoms is greater than 5 and less than 7, and the particle size ratio (Da / Dm) of the average particle size Da determined by the Fisher particle size distribution method to the volume median particle size Dm determined by laser diffraction particle size distribution method is greater than 0.85.

Description

Technical Field

[0001] This disclosure relates to fluoride phosphors and light-emitting devices. Background Technology

[0002] Light-emitting devices combining light-emitting elements and phosphors have been developed in various ways and are used in a wide range of fields, including lighting, automotive lighting, displays, and LCD backlighting. For example, phosphors used in light-emitting devices for LCD backlighting require high color purity, i.e., a narrow half-width at half-maximum (WWHM) of the emission peak. As a red-emitting phosphor with a narrow WWHM of the emission peak, Patent Document 1 discloses a composite fluoride phosphor having a composition, for example, K2SiF6:Mn.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-224536 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In phosphors used in light-emitting devices, in addition to a narrow half-width at half-maximum (WWHM) of the emission peak, increased brightness is also required. For example, regarding the composite fluoride phosphor described in Patent Document 1, there is room for improvement in terms of brightness. Therefore, one objective of this disclosure is to provide a fluoride phosphor with high brightness.

[0008] Problem Solving Methods

[0009] The first type is a fluoride phosphor having the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M contains at least one selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7. The average particle size Da of the fluoride phosphor, determined by the Fisher particle size distribution method, has a particle size ratio (Da / Dm) of 0.85 or greater relative to the volume median particle size Dm determined by laser diffraction particle size distribution method.

[0010] The second method is a method for manufacturing a fluoride phosphor, comprising: preparing fluoride particles having a specific composition, and heating a mixture containing the prepared fluoride particles, an alkali metal, and a liquid medium. The fluoride particles have the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M contains at least one selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7.

[0011] The effects of the invention

[0012] According to one aspect of this disclosure, a high-brightness fluoride phosphor can be provided. Attached Figure Description

[0013] Figure 1 This is a schematic cross-sectional view showing an example of a light-emitting device containing a fluoride phosphor.

[0014] Figure 2 This is an example of a scanning electron microscope (SEM) image of the fluoride phosphor in Example 1.

[0015] Figure 3 This is an example of a SEM image of the fluoride phosphor in Comparative Example 1.

[0016] Symbol Explanation

[0017] 10: Light-emitting element

[0018] 20: First conductor

[0019] 30: Second conductor

[0020] 40: Molded body

[0021] 50: Fluorescent components

[0022] 60: Electrical wire

[0023] 70: Fluorescent material

[0024] 100: Light-emitting device Detailed Implementation

[0025] In this specification, when multiple substances corresponding to each component are present in the composition, unless otherwise specified, the content of each component in the composition represents the total amount of the multiple substances present in the composition. Furthermore, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined from the numerical values ​​shown as examples of numerical ranges. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color names of monochromatic light, etc., are all based on JIS Z8110. The half-width at half maximum (FWHM) of a phosphor refers to the wavelength width of the emission spectrum in which the emission intensity reaches 50% of the maximum emission intensity. The volume median particle size of a phosphor is the volume-based median particle size, which refers to the particle size corresponding to 50% of the cumulative volume from the smallest particle size side in the volume-based particle size distribution. The particle size distribution of a phosphor is determined by laser diffraction using a laser diffraction particle size distribution measuring device. In the formulas representing the composition of phosphors or luminescent materials in this specification, the plurality of elements or ions separated by commas (,) refer to the presence of at least one of these elements or ions in the composition. Furthermore, in the formulas representing the composition of phosphors, the part before the colon (:) represents the parent crystal, and the part after the colon (:) represents the activating element. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below exemplify fluoride phosphors and luminescent devices for embodying the technical concept of the present invention, but the present invention is not limited to the fluoride phosphors and luminescent devices shown below.

[0026] Fluoride phosphors

[0027] Fluoride phosphors have the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms, wherein element M contains at least one selected from Group 4, Group 13, and Group 14 elements. The composition of a fluoride phosphor can be such that, when the total molar number of alkali metals and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7. The particle size ratio (Da / Dm) of the fluoride phosphor, determined by the Fisher particle size distribution method (FSSS method), relative to the volume median particle size Dm determined by laser diffraction particle size distribution method, can be 0.85 or higher. Fluoride phosphors with a particle size ratio (Da / Dm) of 0.85 or higher can exhibit high brightness.

[0028] The volumetric median particle size (Dm) is the cumulative frequency of the smallest particle size in a particle size distribution, measured by laser diffraction particle size distribution (FSSS), corresponding to the 50% particle size distribution. FSSS is a method that uses the scattered light from a laser beam irradiating a particle to determine its particle size distribution. Therefore, when the particles being measured include primary particles and secondary particles (aggregates of primary particles), the particle size distribution is measured as a whole, without distinguishing between primary and secondary particles. In other words, the volumetric median particle size (Dm) is the measured value of the particle group including both primary and secondary particles. On the other hand, the average particle size (Da) measured by the FSSS method is the Fisher Sub-Sieve Sizer's Number. FSSS is a type of air-permeability method that uses the resistance to airflow to measure specific surface area, primarily used to determine the particle size of primary particles.

[0029] Fluoride phosphors can sometimes be used in the manufacture of light-emitting devices in the form of a resin composition dispersed in a resin. The closer the particle size ratio Da / Dm of the fluoride phosphor is to 1, the lower the proportion of secondary particles and the higher the proportion of primary particles in the particle group of the fluoride phosphor. If the proportion of primary particles in the fluoride phosphor particle group increases, there is a tendency to improve the dispersibility of the resin containing the fluoride phosphor. Therefore, the particle size ratio Da / Dm can be set as an indicator of the dispersibility of the resin containing the fluoride phosphor. Furthermore, the particle size of the fluoride phosphor contained in the resin composition used in the manufacture of the light-emitting device is sometimes limited by the median volumetric particle size Dm, which affects the flowability of the resin composition in a dispensing means such as a syringe used for dispensing. On the other hand, there is a tendency for the fluoride phosphor to have higher brightness as the average particle size Da, which is the size of the primary particles, tends to be higher. Therefore, if the fluoride phosphors have the same median particle size Dm, the fluoride phosphors with a particle size ratio Da / Dm close to 1 and a large average particle size Da tend to have higher brightness of the fluoride phosphor itself, and the beam of the light-emitting device manufactured will also be higher.

[0030] From the viewpoint of improving the brightness of fluoride phosphors, the particle size ratio Da / Dm of fluoride phosphors can be, for example, 0.85 or more, preferably 0.87 or more, 0.90 or more, 0.92 or more, 0.94 or more, or 0.97 or more. The particle size ratio Da / Dm is typically 1 or less. The particle size ratio Da / Dm of fluoride phosphors can be set to a desired value by, for example, the manufacturing method of fluoride phosphors described later.

[0031] The volume median particle size Dm of the fluoride phosphor can be, for example, in the range of 25 μm or more and 60 μm or less, preferably in the range of 28 μm or more and 55 μm or less, and more preferably in the range of 30 μm or more and 50 μm or less. If the volume median particle size Dm of the fluoride phosphor is within a given range and the particle size ratio Da / Dm is 0.85 or more, then even when a composition containing resin and fluoride phosphor is injection molded into a molded body using a syringe to form a wavelength conversion component of a light-emitting device, the fluoride phosphor will not clog in the syringe, and the phosphor can be injection molded in a state of dispersion in the resin. This makes it easier to manufacture the light-emitting device more efficiently. Furthermore, the beam size of the resulting light-emitting device can be improved.

[0032] The average particle size Da of the fluoride phosphor, as determined by FSSS, can be, for example, in the range of 20 μm or more and 60 μm or less, preferably in the range of 23 μm or more and 55 μm or more, more preferably in the range of 25 μm or more and 50 μm or less, and can be less than 45 μm or less or less than 40 μm. If the average particle size Da of the fluoride phosphor, as determined by FSSS, is within a given range, and the particle size ratio Da / Dm is 0.85 or more, the fluoride phosphor will not clog the syringe, and the phosphor can be injection molded into a resin composition containing the fluoride phosphor and the resin in a dispersed state. This facilitates more efficient manufacturing of the light-emitting device and improves the beam size of the resulting light-emitting device.

[0033] Regarding the composition of the fluoride phosphor, when the total molar number of alkali metal and ammonium ions is 2, the molar number of Mn can be, for example, greater than 0 and less than 0.2, preferably greater than 0.01 and less than 0.12. Furthermore, regarding the composition of the fluoride phosphor, when the total molar number of alkali metal and ammonium ions is 2, the molar number of element M can be, for example, greater than 0.8 and less than 1, preferably greater than 0.88 and less than 0.99. Regarding the composition of the fluoride phosphor, when the molar number of alkali metal is 2, the molar number of F can be, for example, greater than 5 and less than 7, preferably greater than 5.9 and less than 6.1. The composition of the fluoride phosphor can be analyzed by, for example, fluorescence X-ray analysis, inductively coupled plasma (ICP) luminescence spectrophotometry, etc.

[0034] The alkali metal in the composition of the fluoride phosphor may include at least one selected from lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Additionally, the alkali metal includes at least potassium (K), and may include at least one selected from lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). The ratio of the molar number of K to the total molar number of alkali metal and ammonium ions in the composition may be, for example, 0.90 or more, preferably 0.95 or more, or 0.97 or more. The molar number ratio of K may be, for example, 1 or less or 0.995 or less. The composition of the fluoride phosphor may include ammonium ions (NH4+). + Alkali metals can be replaced by ions. When ammonium ions are included, the ratio of the molar number of ammonium ions to the total molar number of alkali metals and ammonium ions in the composition can be, for example, 0.10 or less, preferably 0.05 or less, or 0.03 or less. The lower limit of the ratio of the molar number of ammonium ions can be, for example, greater than 0, preferably greater than 0.005. The alkali metal in the composition of the fluoride phosphor can be an alkali metal ion.

[0035] The element M in the composition of the fluoride phosphor comprises at least one element selected from Group 4, Group 13, and Group 14 elements. Examples of Group 4 elements include titanium (Ti), zirconium (Zr), and hafnium (Hf), and at least one element selected from these can be included. Examples of Group 13 elements include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl), and at least one element selected from these can be included. Examples of Group 14 elements include carbon (C), silicon (Si), germanium (Ge), and tin (Sn), and at least one element selected from these can be included. In one embodiment, element M may comprise at least one element from Group 14, preferably at least one element selected from Si and Ge, and more preferably at least one element selected from Si. In another embodiment, element M may comprise at least one element from Group 13 and at least one element from Group 14, preferably at least one element selected from Al, Si, and Ge, and more preferably at least one element selected from Al and Si.

[0036] The manganese (Mn) in the composition of fluoride fluorophores may contain manganese ions, and may contain at least tetravalent manganese ions.

[0037] Regarding the composition of the fluoride phosphor, the total number of moles of elements M and Mn relative to the total number of moles of alkali metal and ammonium ions (2) can be 0.9 or more and 1.1 or less, preferably 0.95 or more and 1.05 or less, or 0.97 or more and 1.03 or less.

[0038] The composition of a fluoride phosphor can be represented by the following formula (1).

[0039] Ac [M 1-b Mn b F d (1)

[0040] In formula (1), A may include at least one selected from Li, Na, K, Rb, Cs, and NH4 + Among them. M includes at least Si and may further include at least one element selected from Group 4 elements, Group 13 elements, and Group 14 elements. Mn may be a tetravalent Mn ion. b may satisfy 0 < b < 0.2, and c is the absolute value of the charge of the [M 1-b Mn b F d ion, and d may satisfy 5 < d < 7.

[0041] In formula (1), A includes at least K and may further include at least one selected from Li, Na, Rb, Cs, and NH4 + Among them. The ratio of the molar number of K to the total molar number of A in the composition may be, for example, 0.90 or more, preferably 0.95 or more, or may be 0.97 or more. The upper limit of the ratio of the molar number of K may be, for example, 1 or 0.995 or less.

[0042] In formula (1), b is preferably 0.005 or more and 0.15 or less, 0.01 or more and 0.12 or less, or may be 0.015 or more and 0.1 or less. c may be, for example,​​​​​​​​​​​​​The first composition as a mode of the composition of the fluoride phosphor may contain at least one element selected from Group 4 elements and Group 14 elements as element M, preferably contains at least one element selected from Group 14 elements, more preferably may contain at least one of Si and Ge, and further preferably contains at least Si. In addition, for the first composition of the fluoride phosphor, the total molar number of Si, Ge, and Mn may be 0.9 or more and 1.1 or less, preferably 0.95 or more and 1.05 or less, or may be 0.97 or more and 1.03 or less, relative to the total molar number 2 of alkali metal and ammonium ions.

[0047] The first composition of the fluoride phosphor may be a composition represented by the following formula (2).

[0048] A 1 q [M 1 1-p Mn p F r (2)

[0049] In formula (2), A 1 may contain at least one selected from Li, Na, K, Rb, Cs, and NH4 + . M 1 contains at least one of Si and Ge, and may further contain at least one element selected from Group 4 elements and Group 14 elements. Mn may be tetravalent Mn ions. p may satisfy 0 < p < 0.2, q is the absolute value of the charge of [M 1 1-p Mn p F r ions, and r may satisfy 5 < r < 7.

[0050] A in formula (2) 1 contains at least K, and may further contain at least one selected from Li, Na, Rb, Cs, and NH4 + . When A 1 contains ammonium ions, the ratio of the molar number of ammonium ions to the total molar number of A in the composition 1 may be, for example, 0.10 or less, preferably may be 0.05 or less, or may be 0.03 or less. The lower limit of the ratio of the molar number of ammonium ions may, for example, exceed 0, and preferably may be 0.005 or more.

[0051] In formula (2), p is preferably 0.005 or more and 0.15 or less, 0.01 or more and 0.12 or less, or 0.015 or more and 0.1 or less. q can be, for example, 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less, or 1.95 or more and 2.05 or less. r is preferably 5.5 or more and 6.5 or less, 5.9 or more and 6.1 or less, 5.92 or more and 6.05 or less, or 5.95 or more and 6.025 or less.

[0052] The fluoride phosphor of the first composition can have the first theoretical composition represented by the following formula (2a).

[0053] A 1 2M 1 F6:Mn (2a)

[0054] In equation (2a), A 1 It may contain elements selected from Li, Na, K, Rb, Cs, and NH4. + At least one of them. M 1 It contains at least one of Si and Ge, and may further contain at least one element selected from Group 4 and Group 14 elements. Mn may be a tetravalent Mn ion.

[0055] Regarding the second composition of the fluoride phosphor, element M may include at least one element selected from Group 4 and Group 14, and at least one element selected from Group 13. Preferably, it may include at least one element selected from Group 14 and at least one element selected from Group 13. More preferably, it may include at least Si and Al. Furthermore, regarding the second composition of the fluoride particles, the total molar number of Si, Al, and Mn relative to the total molar number 2 of alkali metal and ammonium ions may be 0.9 or more and 1.1 or less, preferably 0.95 or more and 1.05 or less, or 0.97 or more and 1.03 or less. Additionally, regarding the second composition of the fluoride phosphor, the molar number of Al relative to the total molar number 2 of alkali metal and ammonium ions may be more than 0 and less than 0.1, preferably more than 0 and less than 0.03, more than 0.002 and less than 0.02, or more than 0.003 and less than 0.015.

[0056] The second composition of a fluoride phosphor can be the composition represented by the following formula (3).

[0057] A 2 t [M 2 1-s Mn s F u (3)

[0058] In formula (3), A 2 may include at least one selected from Li, Na, K, Rb, Cs, and NH4 + , preferably includes at least K, and may further include at least one selected from Li, Na, Rb, Cs, and NH4 + . M 2 includes at least Si and Al, and may further include at least one element selected from Group 4 elements, Group 13 elements, and Group 14 elements. Mn may be a tetravalent Mn ion. s may satisfy 0 < s < 0.2, and t is the absolute value of the charge of the 2 1-s s Mn u

[0059] When A in formula (3) 2 includes an ammonium ion, the molar ratio of the ammonium ion to the total molar number of A in the composition 2 may be, for example, below 0.10, preferably below 0.05, or may be below 0.03. The lower limit of the ratio of the molar number of the ammonium ion may be, for example, more than 0, preferably 0.005 or more.

[0060] In formula (3), s is preferably 0.005 or more and 0.15 or less, 0.01 or more and 0.12 or less, or may be 0.015 or more and 0.1 or less. t may be, for example, 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less, or may be 1.95 or more and 2.05 or less. u is preferably 5.5 or more and 6.5 or less, 5.9 or more and 6.1 or less, 5.92 or more and 6.05 or less, or may be 5.95 or more and 6.025 or less.

[0061] The fluoride particles of the second composition may have a second theoretical composition represented by the following formula (3a).

[0062] A<00000�0>2Si 1-v Al v F 6-v :Mn (3a)

[0063] In formula (3a), A 2 may include at least one selected from Li, Na, K, Rb, Cs, and NH4 + , preferably includes at least K, and may further include at least one selected from Li, Na, Rb, Cs, and NH4 + . v may satisfy 0 < v < 1, preferably may satisfy 0.005 < v < 0.03. Mn may be a tetravalent Mn ion.

[0064] ​​Fluoride phosphors are, for example, phosphors activated by tetravalent manganese, which absorb short-wavelength regions of visible light and emit red light. The light illuminating a fluoride phosphor is primarily in the blue region, with a peak wavelength in the range of, for example, 380 nm to 485 nm. The emission peak wavelength in the emission spectrum of a fluoride phosphor can be, for example, 610 nm to 650 nm. The half-width at half-maximum (WWHM) in the emission spectrum of a fluoride phosphor can be, for example, less than 10 nm.

[0065] Method for manufacturing fluoride phosphors

[0066] A method for manufacturing a fluoride phosphor may include: a first step of preparing fluoride particles having a specific composition; and a second step of heating a mixture comprising the prepared fluoride particles and a treatment solution containing an alkali metal and a liquid medium. Here, the fluoride particles having the specific composition may have the following composition: containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms, wherein element M comprises at least one element selected from Group 4, Group 13, and Group 14, and when the total molar number of alkali metals and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7. The alkali metal contained in the treatment solution may at least include potassium.

[0067] Fluoride phosphors with a particle size ratio (Da / Dm) close to 1 can be efficiently manufactured by heating a mixture containing fluoride particles with a specific composition and a processing liquid containing alkali metals and a liquid medium. This can be attributed to, for example, the promotion of recrystallization due to the dissolution and leaching reaction of the fluoride particles through heating the fluoride particles in a liquid medium containing alkali metal ions, thereby increasing the proportion of primary particles in the fluoride particles. The resulting fluoride phosphor has high brightness, and in a light-emitting device equipped with a wavelength conversion component containing a fluoride phosphor and a resin, for example, the light beam is enhanced.

[0068] In the first step, fluoride particles with a specific composition are prepared. This preparation can be achieved by acquiring fluoride particles or by manufacturing the desired fluoride particles. It should be noted that the detailed composition of the prepared fluoride particles is the same as that of the fluoride phosphor described above.

[0069] Fluoride particles can be manufactured, for example, as described below. When the fluoride particles have a first composition, for example, they can be manufactured by a manufacturing method comprising mixing a solution a and a solution b, wherein solution a contains at least a first complex ion containing tetravalent manganese, a second complex ion containing at least one element selected from Group 4 and Group 14 elements and a fluoride ion, and hydrogen fluoride, and solution b contains at least an alkali metal and hydrogen fluoride. Here, the alkali metal contained in the fluoride particles may contain at least potassium.

[0070] Furthermore, fluoride particles having the first composition can be manufactured, for example, by a manufacturing method comprising mixing a first solution, a second solution, and a third solution, wherein the first solution contains at least a first complex ion containing tetravalent manganese and hydrogen fluoride, the second solution contains at least an alkali metal and hydrogen fluoride, and the third solution contains at least a second complex ion containing at least one element selected from Group 4 and Group 14 elements and a fluoride ion. Methods for manufacturing fluoride particles having the first composition can be referenced, for example, Japanese Patent Application Publication Nos. 2014-141684, 2015-143318, and 2015-188075.

[0071] When the fluoride particles have a second composition, the fluoride particles having the second composition can be manufactured, for example, by a manufacturing method including the following steps: preparing fluoride particles having a first composition; preparing fluoride particles containing Al, alkali metals, and F; and subjecting a mixture containing the fluoride particles and the fluoride particles having the first composition to a first heat treatment at a first heat treatment temperature of 600°C or higher and 780°C or lower in an inert gas atmosphere. Here, regarding the composition of the fluoride particles containing Al, alkali metals, and F, the ratio of the total number of alkali metals to the number of moles of Al is 1 or more and 3 or less, and the ratio of the number of moles of F can be 4 or more and 6 or less. Alternatively, the ratio of the total number of alkali metals to the number of moles of Al is 2 or more and 3 or less, and the ratio of the number of moles of F can be 5 or more and 6 or less. The manufacturing method of fluoride particles having the second composition can be found, for example, in Japanese Patent Application Publication No. 2010-254933 and Japanese Patent Application Publication No. 2022-099232. Here, the alkali metal contained in the fluoride particles may include at least potassium.

[0072] In the second step, the mixture, which includes prepared fluoride particles and a treatment liquid containing an alkali metal and a liquid medium, is heated. The alkali metal contained in the treatment liquid is the same as the alkali metal contained in the composition of the fluoride particles, and the alkali metal contained in the treatment liquid and the alkali metal contained in the composition of the fluoride particles can be the same. Furthermore, the alkali metal contained in the treatment liquid can be in the form of alkali metal ions. In addition, the alkali metal contained in the treatment liquid can contain at least potassium. When the alkali metal contained in the treatment liquid contains potassium, the ratio of the number of moles of potassium to the total number of moles of alkali metal in the treatment liquid can be, for example, 0.90 or more, preferably 0.95 or more, or 0.97 or more, for example, 1 or 0.995 or less. When the treatment liquid contains potassium, potassium hydrogen fluoride (KHF2), potassium nitrate (KNO3), potassium fluoride (KF), etc., can be contained as inorganic acid salts, and can be contained in the state where the inorganic acid salt is dissolved in the liquid medium.

[0073] The content of alkali metals in the treatment solution can be, for example, 5% by mass or more and 30% by mass or less, preferably 10% by mass or more, 12% by mass or more, 15% by mass or more, 18% by mass or more, or 20% by mass or more, for example, 28% by mass or less or 25% by mass or less.

[0074] There are no particular limitations on the liquid medium, and it can be appropriately selected from commonly used liquids depending on the purpose, etc. Specifically, examples of liquid media include: water; alcohol solvents such as methanol, ethanol, and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; organic solvents such as diethyl ether and diisopropyl ether; etc. Furthermore, the liquid medium can be a substance that is a gas at normal pressure but is liquefied by pressure, or a substance that is a solid at room temperature but is liquefied by heating. The liquid medium preferably contains at least water, and can be substantially water. The liquid medium can be a single substance or a combination of two or more substances.

[0075] The treatment solution may further contain components soluble in a liquid medium. Examples of components soluble in a liquid medium include inorganic acids such as hydrogen fluoride (HF), hexafluorosilicic acid (H₂SiF₆), and nitric acid (HNO₃); and peroxides such as hydrogen peroxide. One component soluble in the liquid medium may be used alone, or two or more may be used in combination. The treatment solution may contain at least hydrogen fluoride. When the treatment solution contains hydrogen fluoride, the content of hydrogen fluoride in the treatment solution may be, for example, 10% by mass or more and 80% by mass or less, preferably 20% by mass or more, 40% by mass or more, or 60% by mass or more, and may be 75% by mass or less, 70% by mass or less, or 65% by mass or less.

[0076] As a mass ratio relative to the fluoride particles, the amount of treatment liquid used in the mixture can be, for example, 50% by mass or more and 500% by mass or less, preferably 80% by mass or more, 85% by mass or more, or 100% by mass or more, and even more preferably 300% by mass or less, 200% by mass or less, or 150% by mass or less. If the mass ratio of the treatment liquid is within the above range, there is a tendency to produce fluoride phosphors with a higher proportion of primary particles.

[0077] The heat treatment temperature in the second step only needs to be, for example, 150°C or higher and lower than 230°C. Preferably, the heat treatment temperature can be 160°C or higher, 170°C or higher, or 180°C or higher, more preferably 225°C or lower, or lower than 220°C. If the heat treatment temperature is 150°C or higher, the recrystallization caused by the dissolution and efflux reaction of the fluoride phosphor proceeds more smoothly, resulting in a fluoride phosphor with a high proportion of primary particles and a particle size ratio (Da / Dm) close to 1. Furthermore, if the heat treatment temperature is lower than 230°C, the deterioration of the container used in the heat treatment can be suppressed.

[0078] The heat treatment time can be appropriately selected based on processing conditions such as temperature. The heat treatment time can be, for example, 4 hours or more but less than 24 hours, preferably 8 hours or more, 12 hours or more, or 14 hours or more, and less than 20 hours or less than 18 hours. When the heat treatment time is 4 hours or more, there is a tendency to produce fluoride phosphors with a higher proportion of primary particles. Furthermore, a time of 24 hours or less is advantageous from a manufacturing efficiency perspective. There are no particular limitations on the atmosphere used in the heat treatment; it can be an atmospheric atmosphere or an inert gas atmosphere.

[0079] The heat treatment of the mixture can be performed by adding the mixture into a pressure-resistant, sealed container, such as an autoclave, and heating it. By using a pressure-resistant, sealed container for heat treatment, the mixture can be pressurized and heated. That is, the heat treatment of the mixture in the second step can be a pressurized heat treatment of the mixture. The pressure-resistant, sealed container can be a container whose inner surface is coated with a fluoropolymer such as polytrifluoroethylene (PTFE) and made of stainless steel, or it can be a container having a fluoropolymer sample container and a pressure-resistant, sealable outer cylinder that encloses the sample container.

[0080] The method for manufacturing fluoride phosphors may further include: a step of recovering the fluoride phosphors obtained in the second step by solid-liquid separation after the second step; a step of drying the fluoride phosphors after solid-liquid separation; and a step of dispersing the dried fluoride phosphors, etc.

[0081] Light-emitting device

[0082] The light-emitting device may include a fluoride phosphor and a light source having a peak emission wavelength in the wavelength range of 380 nm to 485 nm. The light-emitting device may further include other constituent components as needed. The fluoride phosphor may be used as a wavelength conversion component, for example, comprising a fluoride phosphor and a resin, to construct the light-emitting device.

[0083] An example of a light-emitting device is described based on the accompanying drawings. Figure 1 This is a schematic cross-sectional view showing an example of the light-emitting device according to this embodiment. This light-emitting device is an example of a surface-mount type light-emitting device. The light-emitting device 100 includes: a light-emitting element 10, and a molded body 40 for mounting the light-emitting element 10, the light-emitting element 10 being a light source emitting light with a peak wavelength in the short wavelength range of visible light (e.g., between 380 nm and 485 nm). The molded body 40 has a first conductive line 20 and a second conductive line 30, and is integrally molded from a thermoplastic resin or a thermosetting resin. The molded body 40 has a recess having a bottom surface and a side surface corresponding to a substrate, and the light-emitting element 10 is mounted on the bottom surface of the recess. The light-emitting element 10 has a pair of positive and negative electrodes, which are electrically connected to the first conductive line 20 and the second conductive line 30 via wires 60. The light-emitting element 10 is covered by a wavelength conversion member 50. The wavelength conversion member 50 contains a phosphor 70, which includes a fluoride phosphor that performs wavelength conversion on the light from the light-emitting element 10. The phosphor 70 may further comprise the aforementioned fluoride phosphor and luminescent material, wherein the luminescent material emits light with a peak emission wavelength in a different wavelength range than that of the fluoride phosphor by the action of excitation light from the luminescent element 10.

[0084] The wavelength conversion component may include a resin and a phosphor. Examples of resins constituting the wavelength conversion component include silicone resins, epoxy resins, modified silicone resins, modified epoxy resins, and acrylic resins. For example, the refractive index of the silicone resin may be 1.35 or higher and 1.55 or lower, more preferably 1.38 or higher and 1.43 or lower. If the refractive index of the silicone resin is within these ranges, it exhibits excellent light transmittance and can be suitably used as a resin constituting the wavelength conversion component. Here, the refractive index of the silicone resin is the refractive index after curing, measured according to JIS K7142:2008. In addition to the resin and phosphor, the wavelength conversion component may further include a light-diffusing material. By including a light-diffusing material, the directivity from the light-emitting element can be mitigated, thereby increasing the viewing angle. Examples of light-diffusing materials include silicon oxide, titanium oxide, zinc oxide, zirconium oxide, and aluminum oxide.

[0085] The light-emitting element emits light with a peak emission wavelength in the short wavelength region of visible light, ranging from 380 nm to 485 nm. The light-emitting element can be a light source for exciting a fluoride phosphor. Preferably, the light-emitting element has a peak emission wavelength in the range of 380 nm to 480 nm, more preferably in the range of 410 nm to 480 nm, and even more preferably in the range of 430 nm to 480 nm. Semiconductor light-emitting elements are preferred as light-emitting elements used as light sources. By using semiconductor light-emitting elements in the light source, a light-emitting device with high efficiency, high linearity of output relative to input, and strong and stable resistance to mechanical shock can be obtained. For example, semiconductor light-emitting elements using nitride-based semiconductors can be used as semiconductor light-emitting elements. The half-width of the emission peak in the emission spectrum of the light-emitting element is preferably, for example, 30 nm or less.

[0086] The light-emitting device is constructed by incorporating a fluoride phosphor. Details regarding the fluoride phosphor contained in the light-emitting device are as described above. The fluoride phosphor is, for example, included in a wavelength conversion member covering the light source. In a light-emitting device where the light source is covered by a wavelength conversion member containing a fluoride phosphor, a portion of the light emitted by the light source is absorbed by the fluoride phosphor and emitted as red light. By using a light source that emits light with a peak emission wavelength in the range of 380 nm to 485 nm, the emitted light can be utilized more effectively, and the loss of light emitted from the light-emitting device can be reduced, thereby providing a highly efficient light-emitting device.

[0087] In addition to the fluoride phosphor, the light-emitting device preferably further includes a light-emitting material other than the fluoride phosphor. The light-emitting material other than the fluoride phosphor can absorb light from the light source and convert its wavelength to a different wavelength than that of the fluoride phosphor. The light-emitting material can, for example, be included in the wavelength conversion component in the same way as the fluoride phosphor.

[0088] The luminescent material may have an emission peak wavelength in a wavelength range of more than 495 nm and less than 573 nm, and preferably may be at least one selected from β - sialon phosphors, halosilicate phosphors, silicate phosphors, rare - earth aluminate phosphors, and nitride phosphors. The β - sialon phosphor may have a composition represented by, for example, the following formula (IIa). The halosilicate phosphor may have a composition represented by, for example, the following formula (IIb). The silicate phosphor may have a composition represented by, for example, the following formula (IIc). The rare - earth aluminate phosphor may have a composition represented by the following formula (IId). The nitride phosphor may have a composition represented by, for example, the following formula (IIe), (IIf), or (IIg). By including a β - sialon phosphor as a luminescent material other than a fluoride phosphor, the wavelength - conversion member can widen the range of color reproducibility of the light - emitting device when the light - emitting device is used as a backlight source, for example. By including a halosilicate phosphor, a silicate phosphor, a rare - earth aluminate phosphor, or a nitride phosphor as a luminescent material other than a fluoride phosphor, the wavelength - conversion member can improve the color rendering property or the luminous efficiency of the light - emitting device when the light - emitting device is used as a lighting source, for example.

[0089] Si 6-x Al x O x N 8-x :Eu (IIa)

[0090] (In formula (IIa), x is a number satisfying 0 < x ≤ 4.2.)

[0091] (Ca,Sr,Ba)8MgSi4O 16 (F,Cl,Br)2:Eu (IIb)

[0092] (Ba,Sr,Ca,Mg)2SiO4:Eu (IIc)

[0093] (Y,Lu,Gd,Tb)3(Al,Ga)5O 12 :Ce (IId)

[0094] (La,Y,Gd)3Si6N 11 :Ce (IIe)

[0095] (Sr,Ca)LiAl3N4:Eu (IIf)

[0096] (Ca,Sr)AlSiN3:Eu (IIg)

[0097] In addition to the fluoride phosphor, the wavelength conversion member may further contain at least one of quantum dots. The quantum dots can absorb light from a light source and convert its wavelength into light having a wavelength different from that of the fluoride phosphor, or can convert it into light having the same level of wavelength. Examples of the quantum dots include: quantum dots having a perovskite structure with a composition such as (Cs,FA,MA)(Pb,Sn)(Cl,Br,I)3 (where FA refers to formamidine , MA refers to methylammonium); quantum dots having a chalcopyrite structure with a composition such as (Ag,Cu,Au)(In,Ga)(S,Se,Te)2; semiconductor quantum dots such as (Cd,Zn)(Se,S); InP-based semiconductor quantum dots, etc., and at least one selected from them may be included. By including quantum dots as a luminescent material in addition to the fluoride phosphor, when the light-emitting device is used as a backlight light source, for example, the range of color reproducibility of the light-emitting device can be made wider.

[0098] The invention of the present disclosure may include, for example, the following modes.

[0099] [1] A fluoride phosphor having the following composition:

[0100] containing element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms, the element M containing at least one selected from Group 4 elements, Group 13 elements, and Group 14 elements, when the total molar number of the above alkali metals and ammonium ions is 2, the molar number of manganese exceeds 0 and is less than 0.2, the total molar number of element M exceeds 0.8 and is less than 1, and the molar number of fluorine atoms exceeds 5 and is less than 7,

[0101] The particle size ratio (Da / Dm) of the average particle size Da measured by the Fisher particle size method to the volume median particle size Dm measured by the laser diffraction particle size distribution measurement method is 0.85 or more. <​​​​​​​​​​​​​​​​​​​​​​The absolute value of the charge of an ion, d, satisfies 5. <d<7。

[0105] [3] The fluoride phosphor according to [1] or [2], wherein,

[0106] The average particle size Da, as determined by the Fisher particle size distribution method, is greater than 20 μm and less than 60 μm.

[0107] [4] A light-emitting device comprising:

[0108] The fluoride phosphor described in any one of [1] to [3], and

[0109] A light source having a peak emission wavelength in the wavelength range of 380nm to 485nm.

[0110] [5] The light-emitting device according to [4] further includes a light-emitting material having a peak emission wavelength in a wavelength range of 495 nm or higher and 573 nm or lower.

[0111] [6] A method for manufacturing a fluoride phosphor, the method comprising:

[0112] Prepare fluoride particles having the following composition: comprising element M, at least one selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M comprises at least one selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7.

[0113] The mixture is subjected to heat treatment, the mixture comprising the prepared fluoride particles and a treatment solution comprising an alkali metal and a liquid medium.

[0114] [7] According to the method for manufacturing fluoride phosphors described in [6], wherein,

[0115] The alkali metal content in the treatment solution is 10% by mass or more.

[0116] [8] The method for manufacturing a fluoride phosphor according to [6] or [7], wherein,

[0117] The treatment solution further contains hydrogen fluoride.

[0118] [9] According to the method for manufacturing fluoride phosphors described in [8], wherein,

[0119] The hydrogen fluoride content in the treatment solution is 40% by mass or more.

[0120]

[10] The method for manufacturing a fluoride phosphor according to any one of [6] to [9], wherein,

[0121] The temperature of the heat treatment is above 180°C.

[0122] Example

[0123] The embodiments of this disclosure will be described in more detail below, but the embodiments of this disclosure are not limited to these embodiments.

[0124] Manufacturing Example 1

[0125] 7029 g of KHF2 was weighed and dissolved in 37.3 L of a 55% (w / w) aqueous solution of hydrogen fluoride (HF) to prepare a first solution. Separately, 314.2 g of K2MnF6 was weighed and dissolved in 6.0 L of a 55% (w / w) aqueous solution of HF to prepare a second solution. Next, 7.8 L of an aqueous solution containing 40% (w / w) H2SiF6 was prepared to prepare a third solution. The first solution was then added dropwise over approximately 10 hours with stirring at 20°C to the second and third solutions. After the addition was complete, 400 ml of a 35% hydrogen peroxide aqueous solution was added, followed by washing with pure water. The resulting precipitate was subjected to solid-liquid separation, washed with ethanol, and dried at 90°C for 10 hours, thereby producing the fluoride particles P1 of Manufacturing Example 1.

[0126] The obtained fluoride particles P1 have an average particle size Da = 20.5 μm and possess K2[Si 0.961 Mn 0.039 The composition represented by F6].

[0127] Manufacturing Example 2

[0128] 7029g of KHF2 was weighed and dissolved in 41.3L of a 55% by mass HF aqueous solution to prepare a first solution. 333.8g of K2MnF6 was weighed and dissolved in 6.0L of a 55% by mass HF aqueous solution to prepare a second solution. Otherwise, fluoride particles P2 of Manufacturing Example 2 were manufactured by the same method as in Manufacturing Example 1.

[0129] The obtained fluoride particles P2 have an average particle size Da = 40.0 μm and possess K2[Si 0.963 Mn 0.037 The composition represented by F6].

[0130] Manufacturing Example 3

[0131] 7029g of KHF2 was weighed and dissolved in 42.0L of a 55% by mass HF aqueous solution to prepare a first solution. 340.4g of K2MnF6 was weighed and dissolved in 6.0L of a 55% by mass HF aqueous solution to prepare a second solution. Otherwise, fluoride particles P3 of Manufacturing Example 3 were manufactured by the same method as in Manufacturing Example 1.

[0132] The obtained fluoride particles P3 have an average particle size Da = 50.0 μm and possess K2[Si] 0.962 Mn 0.038 The composition represented by F6].

[0133] Manufacturing Example 4

[0134] 7029g of KHF2 was weighed and dissolved in 36.5L of a 55% by mass HF aqueous solution to prepare a first solution. 484.4g of K2MnF6 was weighed and dissolved in 6.0L of a 55% by mass HF aqueous solution to prepare a second solution. Otherwise, fluoride particles P4 of Manufacturing Example 4 were manufactured by the same method as in Manufacturing Example 1.

[0135] The obtained fluoride particles P4 have an average particle size Da = 18.5 μm and possess K2[Si] 0.941 Mn 0.059 The composition represented by F6].

[0136] Manufacturing Example 5

[0137] 7029g of KHF2 was weighed and dissolved in 40.0L of 55% by mass HF aqueous solution to prepare a first solution. 497.5g of K2MnF6 was weighed and dissolved in 6.0L of 55% by mass HF aqueous solution to prepare a second solution. Otherwise, fluoride particles P5 of Manufacturing Example 5 were manufactured by the same method as in Manufacturing Example 1.

[0138] The obtained fluoride particles P5 have an average particle size Da = 31.5 μm and possess K2[Si 0.944 Mn 0.056 The composition represented by F6].

[0139] Example 1

[0140] 50g of the fluoride particles P1 manufactured in Example 1 were weighed and placed into a 100ml PTFE sample container (manufactured by Sanai Chemical Co., Ltd.: HUT-100R). Next, 75g of a treatment solution (potassium concentration: 20% by mass) prepared by dissolving 30g of KHF2 in 45g of a 65% by mass HF aqueous solution was added. After stirring and slurrying to form a mixture, the container was capped. The capped sample container was placed in a stainless steel outer cylinder (manufactured by Sanai Chemical Co., Ltd.: HUS-100) and heated in a thermostat at 190°C for 16 hours.

[0141] After heat treatment, the PTFE sample container was removed from the stainless steel outer cylinder. The precipitate in the sample container was transferred to a beaker, and 600 ml of 1% hydrogen peroxide aqueous solution was added for cleaning. After solid-liquid separation, it was cleaned with ethanol and dried at 90°C for 10 hours. After drying, a wet dispersion treatment using polyethylene beads was performed for 1 hour. After solid-liquid separation, it was cleaned with hydrogen peroxide aqueous solution and ethanol and dried at 90°C for 10 hours, thereby producing the fluoride phosphor of Example 1.

[0142] Example 2

[0143] The fluoride particles P2 manufactured in Manufacturing Example 2 were used, and the fluoride phosphor of Example 2 was otherwise produced by the same method as in Example 1.

[0144] Example 3

[0145] The fluoride particles P3 manufactured in Manufacturing Example 3 were used, and the fluoride phosphor of Example 3 was otherwise produced by the same method as in Example 1.

[0146] Example 4

[0147] The fluoride particles P4 manufactured in Manufacturing Example 4 were used, and the fluoride phosphor of Example 4 was otherwise produced by the same method as in Example 1.

[0148] Example 5

[0149] The fluoride particles P5 manufactured in Manufacturing Example 5 were used, and the fluoride phosphor of Example 5 was otherwise produced by the same method as in Example 5.

[0150] Example 6

[0151] The treatment solution used in the heat treatment was changed to a treatment solution prepared by dissolving 37.5 g of KHF2 in 37.5 g of 65% by mass HF aqueous solution (potassium concentration: 25% by mass). Otherwise, the fluoride phosphor of Example 6 was prepared by the same method as in Example 2.

[0152] Example 7

[0153] The treatment solution used in the heat treatment was changed to a treatment solution prepared by dissolving 15g of KHF2 in 60g of a 65% by mass HF aqueous solution (potassium concentration: 10% by mass). Otherwise, the fluoride phosphor of Example 7 was prepared by the same method as in Example 1.

[0154] Comparative Example 1

[0155] The fluoride particles P1 produced in Manufacturing Example 1 were subjected to a wet dispersion treatment of polyethylene beads for 1 hour, similar to that in Example 1. After solid-liquid separation, they were washed with hydrogen peroxide aqueous solution and ethanol, and dried at 90°C for 10 hours, thereby producing the fluoride phosphor of Comparative Example 1.

[0156] Comparative Example 2

[0157] The fluoride particles P2 manufactured in Manufacturing Example 2 were used, and the fluoride phosphor of Comparative Example 2 was otherwise produced by the same method as Comparative Example 1.

[0158] Comparative Example 3

[0159] The fluoride particles P3 manufactured in Manufacturing Example 3 were used. Otherwise, the fluoride phosphor of Comparative Example 3 was prepared by the same method as Comparative Example 1.

[0160] Comparative Example 4

[0161] For the fluoride particles P1 manufactured in Manufacturing Example 1, heat treatment was performed in an atmosphere with a fluorine (F2) concentration of 20% by volume and a nitrogen concentration of 80% by volume, while in contact with fluorine gas at a temperature of 500°C for 8 hours. Next, a wet dispersion treatment using polyethylene beads was performed for 1 hour. After solid-liquid separation, the particles were washed with an aqueous hydrogen peroxide solution and ethanol, and dried at 90°C for 10 hours, thereby producing the fluoride phosphor of Comparative Example 4.

[0162] Comparative Example 5

[0163] The treatment solution used in the heat treatment was changed to a treatment solution prepared by dissolving 10g of KHF2 in 45g of a 65% by mass HF aqueous solution (potassium concentration: 9% by mass). Otherwise, the fluoride phosphor of Comparative Example 5 was prepared by the same method as in Example 1.

[0164] evaluate

[0165] The fluoride phosphors obtained above were evaluated as follows. The results are shown in Table 1.

[0166] 1. Average particle size Da

[0167] The average particle size Da was determined by FSSS using a Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific).

[0168] 2. Bulk median particle size Dm

[0169] The volume median particle size (Dm) was determined using a laser diffraction particle size distribution measuring device (product name: MASTER SIZER3000, manufactured by MALVERN) as the particle size at which the volume cumulative frequency reaches 50% from the small particle size side.

[0170] 3. Emission spectrum and relative brightness

[0171] The emission spectra of each fluoride phosphor at room temperature (25°C) were measured using a spectrophotometer (product name: QE-2000, manufactured by Otsuka Electronics Co., Ltd.) and excitation light with a peak emission wavelength of 450 nm.

[0172] Based on the measured emission spectrum data, the brightness of the fluoride phosphor of Comparative Example 1 was set to 100%, and the brightness of the fluoride phosphors other than those of Comparative Example 1 was calculated as the relative brightness.

[0173] 4. Mn quantity (variable b)

[0174] The content of Mn was determined by using a fluorescence X-ray analysis device (XRF; product name: ZSX PrimusII, manufactured by Rigaku Co., Ltd.) and the molar ratio of Mn in 1 mole of the composition represented by formula (I) (variable b).

[0175] 5. SEM images

[0176] SEM images of the fluoride phosphors were obtained using a scanning electron microscope (SEM). The SEM image of Example 1 is shown below. Figure 2 The SEM image of Comparative Example 1 is shown in Figure 3 .

[0177]

[0178] As shown in Table 1, the fluoride phosphors of Examples 1-6 exhibited higher relative brightness than the fluoride phosphors of the comparative examples. Furthermore, it can be seen that since the particle size of the fluoride phosphors in the examples is closer to 1 than the Da / Dm ratio, the dispersibility is further improved.

Claims

1. A fluoride phosphor having the following composition: The mixture comprises element M, at least one element selected from alkali metals and ammonium ions, manganese, and fluorine atoms. Element M comprises at least one element selected from Group 4, Group 13, and Group 14 elements. When the total molar number of the alkali metal and ammonium ions is 2, the molar number of manganese is greater than 0 and less than 0.2, the total molar number of element M is greater than 0.8 and less than 1, and the molar number of fluorine atoms is greater than 5 and less than 7. The ratio of the average particle size Da determined by the Fisher particle size distribution method to the volume median particle size Dm determined by the laser diffraction particle size distribution method (Da / Dm) is greater than 0.

85.

2. The fluoride phosphor according to claim 1, having the composition represented by the following formula (1): A c [M 1-b Mn b F d ] (1) In formula (1), A includes at least one selected from Li, Na, K, Rb, Cs, and NH4 + M includes at least one element selected from Group 4 elements, Group 13 elements, and Group 14 elements, and at least includes Si, b satisfies 0 < b < 0.2, c is the absolute value of the charge of 1-b Mn b F d ions, and d satisfies 5 < d < 7.

3. The fluoride phosphor according to claim 1, wherein, The average particle size Da, as determined by the Fisher particle size distribution method, is greater than 20 μm and less than 60 μm.

4. A light-emitting device comprising: The fluoride phosphor according to any one of claims 1 to 3, and A light source having a peak emission wavelength in the wavelength range of 380nm to 485nm.

5. The light-emitting device according to claim 4, further comprising a light-emitting material having a peak emission wavelength in a wavelength range of 495 nm or higher and 573 nm or lower.

Images