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• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/61—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements

Definitions

• the present disclosure relates to a method for manufacturing a double fluoride phosphor.
• LEDs Light emitting diodes
• Image display devices using LEDs generally use LEDs that include a blue light emitting diode and a yellow phosphor.
• green phosphors and red phosphors have been used in combination in place of yellow phosphors.
• red phosphors have been studied from the viewpoint of improving color rendering properties.
• a phosphor has a structure in which an element serving as a luminescent center is dissolved in a host crystal.
• the red phosphor include a double fluoride phosphor in which Mn 4+ is dissolved as a luminescent center in a host crystal made of a double fluoride.
• the double fluoride phosphor for example, a manganese -activated double fluoride phosphor ( hereinafter referred to as (also referred to as KSF phosphor).
• KSF phosphors are attracting attention because they are efficiently excited by blue light and have an emission spectrum with a narrow half-width.
• a method for producing a KSF phosphor is, for example, by preparing multiple types of hydrofluoric acid aqueous solutions in which raw materials having the constituent elements of the phosphor are dissolved in a hydrofluoric acid aqueous solution, and mixing and reacting the solutions. , or a method of producing a phosphor by reacting the above hydrofluoric acid aqueous solution with a solid raw material (for example, Patent Document 1), or a method of producing a phosphor by reacting the above hydrofluoric acid aqueous solution with a solid raw material, or a method of producing a phosphor by reacting a raw material having the constituent elements of the phosphor with a hydrofluoric acid aqueous solution.
• a method of manufacturing a phosphor by preparing aqueous solutions of multiple types of dissolved hydrofluoric acid, mixing and reacting them, and further adding a solvent that becomes a poor solvent for the phosphor to precipitate the phosphor e.g. , Patent Document 2
• Potassium hexafluoromanganate represented by the general formula: K 2 MnF 6 is used as a raw material in the above-described method for producing the KSF phosphor. From the viewpoint of improving the fluorescence properties of the KSF phosphor, it is beneficial to increase the amount of solid solution of manganese, and one possible means for this is to add a large amount of potassium hexafluoromanganate. However, since potassium hexafluoromanganate is expensive, this may lead to an increase in the price of the KSF phosphor.
• An object of the present disclosure is to provide a manufacturing method capable of manufacturing a double fluoride phosphor that has a high absorption rate for light at 455 nm and excellent internal quantum efficiency.
• the present disclosure provides the following [1] to [4].
• a method for producing a double fluoride phosphor comprising: A reaction step in which a silicon source and a manganese source are added to a solution of hydrofluoric acid in which potassium hydrogen fluoride is dissolved, and the potassium hydrogen fluoride, the silicon source, and the manganese source are reacted at 0° C. or lower. including; The concentration of the hydrofluoric acid is 58% by mass or more, A manufacturing method, wherein the manganese source contains potassium hexafluoromanganate. [2] The manufacturing method according to [1], wherein in the reaction step, the blending ratio of the amount of manganese to the amount of silicon is 0.15 or less.
• One aspect of the present disclosure is a method for producing a double fluoride phosphor, in which a silicon source and a manganese source are added to a solution of hydrofluoric acid in which potassium hydrogen fluoride is dissolved, and the hydrogen fluoride A reaction step of reacting potassium, the silicon source, and the manganese source at 0° C. or lower, wherein the concentration of the hydrofluoric acid is 58% by mass or more, and the manganese source contains potassium hexafluoromanganate. , provides a manufacturing method.
• the above manufacturing method uses highly concentrated hydrofluoric acid and allows the reaction of potassium hydrogen fluoride, a silicon source, and a manganese source to proceed in a solution at a low temperature.
• a double fluoride phosphor with excellent quantum efficiency can be produced.
• tetravalent manganese which is the luminescent center
• MnF 6 2- complex ions in a part of K 2 SiF 6 , it is necessary to generate MnF 6 2- complex ions in the reaction solution, but the above complex ions are unstable.
• the present inventors have found through studies that the complex ions are stabilized by increasing the concentration of fluoride ions in the solution, and that they are further stabilized in a low-temperature environment.
• the production method according to the present disclosure was made based on this knowledge, and is made by stabilizing the complex ion in the reaction solution and efficiently dissolving tetravalent manganese in K 2 SiF 6 . , it has become possible to provide a double fluoride phosphor that is excellent in both absorption rate and internal quantum efficiency.
• the blending ratio of the amount of manganese to the amount of silicon may be 0.15 or less.
• the amount of manganese to be blended by controlling the amount of manganese to be blended within the above range, it is possible to further suppress the occurrence of concentration quenching in fluorescence emission due to excessive solid solution amount of manganese in the obtained double fluoride phosphor. can.
• the temperature of the solution in the reaction step may be -30 to -5°C.
• the complex ion of MnF 6 2- can be more stabilized and the reaction can proceed gently, thereby making it possible to obtain a more homogeneous double fluoride phosphor. .
• the concentration of the hydrofluoric acid may be 58 to 70% by weight.
• concentration of the hydrofluoric acid is within the above range, the complex ion of MnF 6 2- can be further stabilized, and the amount of solid solution of manganese can be further improved.
• the materials exemplified in this specification can be used alone or in combination of two or more. If there are multiple substances corresponding to each component in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. .
• a numerical range indicated using " ⁇ " indicates a range that includes the numerical values written before and after " ⁇ " as the minimum and maximum values, respectively.
• One embodiment of the method for manufacturing a double fluoride phosphor is a method for manufacturing a double fluoride phosphor, in which a silicon source and a manganese source are added to a solution of hydrofluoric acid in which potassium hydrogen fluoride is dissolved. and reacting the potassium hydrogen fluoride, the silicon source, and the manganese source at 0° C. or lower.
• the concentration of the hydrofluoric acid used in the reaction step is 58% by mass or more.
• the manganese source used in the reaction step contains potassium hexafluoromanganate.
• the lower limit of the concentration of hydrofluoric acid is 58% by mass or more, but may be, for example, 59% by mass or more, 60% by mass or more, 62% by mass or more, or 65% by mass or more.
• the upper limit of the concentration of hydrofluoric acid is, for example, 80% by mass or less, 78% by mass or less, 76% by mass or less, 74% by mass or less, 72% by mass or less, 70% by mass or less, or 68% by mass or less. It's fine.
• the concentration of hydrofluoric acid may be adjusted within the ranges mentioned above, and may be, for example, from 58 to 70% by weight, or from 58 to 68% by weight.
• Potassium hydrogen fluoride (KHF 2 ) can also be a source of potassium (K) in double fluoride phosphors.
• a silicon source is a compound that serves as a source of silicon (Si) in a double fluoride phosphor.
• Examples of the silicon source include silicon dioxide (SiO 2 ), hydrogen silicofluoride (H 2 SiF 6 ), and potassium silicofluoride (K 2 SiF 6 ).
• the silicon source preferably includes silicon dioxide.
• the manganese source is a compound that serves as a source of manganese (Mn) in the double fluoride phosphor.
• the manganese source contains potassium hexafluoromanganate (K 2 MnF 6 ). Note that potassium hexafluoromanganate is ionized in hydrofluoric acid to produce a complex ion of MnF 6 2- .
• MnF 6 2 ⁇ can also provide fluorine (F) in addition to manganese to form a phosphor with the general formula: K 2 SiF 6 :Mn 4+ .
• the temperature of the solution in this case may be controlled at 0°C or lower, and may be controlled at -30 to -5°C.
• the amount of the manganese source added may be adjusted from the viewpoint of improving the efficiency of solid solution of manganese.
• the upper limit of the blending ratio of the amount of manganese to the amount of silicon may be, for example, 0.15 or less, 0.14 or less, 0.13 or less, 0.12 or less, or 0.11 or less.
• the lower limit of the blending ratio of the amount of manganese to the amount of silicon is, for example, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, or 0.09 or more. It's good to be there.
• the blending ratio of the amount of manganese to the amount of silicon may be adjusted within the above-mentioned range, and may be, for example, 0.05 to 0.15, or 0.09 to 0.13.
• the total amount may be added at once, or the planned addition amount may be added in two or more portions (divided addition). From the viewpoint of obtaining phosphor particles having a more uniform composition distribution, it is desirable to add the manganese source to the solution by dividing the planned addition amount into two or more times. It may be 6 times, 2-4 times, or 3-4 times. When adding in portions, the amount added each time may be the same. In the manufacturing method according to the present disclosure, since the prepared solution is reacted in a low-temperature environment, a relatively long reaction time can be provided.
• the reaction time may be, for example, 1 to 60 minutes, or 5 to 30 minutes.
• the solution prepared as described above (also referred to as reaction solution) is reacted at a temperature of 0° C. or lower.
• the upper limit of the temperature of the solution at this time may be, for example, -5°C or lower, -8°C or lower, -10°C or lower, -12°C or lower, or -14°C or lower.
• the lower limit of the temperature of the solution may be, for example, -30°C or higher, -27°C or higher, -24°C or higher, -22°C or higher, -20°C or higher, -18°C or higher, or -16°C or higher.
• synthesis can be performed without freezing the solvent.
• the temperature of the solution in the reaction step may be adjusted within the above-mentioned range, and may be, for example, -30 to -5°C, or -16 to -5°C.
• the above-mentioned manufacturing method may include other steps in addition to the above-mentioned mixing step.
• Another step may include a step of filtering and washing the fluoride phosphor precipitated in the mixed solution.
• water and alcohol can be used to clean the phosphor.
• the alcohol may be, for example, ethanol.
• the double fluoride phosphor obtained by the above manufacturing method may include a KSF phosphor represented by the general formula: K 2 Si 1-x F 6 :Mn 4+ x .
• x is 0.10 or less, for example, 0.01 to 0.10, 0.03 to 0.10, 0.05 to 0.10, 0.08 to 0.10, or 0. It may be between 0.08 and 0.09.
• Manganese is a multivalent ion, and there are also manganese such as Mn 2+ and Mn 3+ that do not contribute to light emission, but the proportion of manganese in the above-mentioned double fluoride phosphor obtained by the manufacturing method according to the present disclosure is mostly tetravalent. It has become.
• potassium, silicon, and manganese can be quantitatively analyzed by ICP-MS method. Furthermore, in the composition of the constituent elements of the above-mentioned double fluoride phosphor, fluorine can be analyzed by ion chromatography. That is, by the above-mentioned measurement, it is possible to identify the above-mentioned double fluoride phosphor and confirm that its composition is expressed as K 2 Si 1-x F 6 :Mn 4+ x . Simply perform X-ray diffraction measurement on the measurement target and check whether a diffraction pattern can be observed at the same position as the standard sample of KSF phosphor. You can check whether it is.
• the double fluoride phosphor obtained by the above manufacturing method has a high absorption rate for light at 455 nm and can have excellent internal quantum efficiency.
• the internal quantum efficiency which is an index showing how many photons of excitation light absorbed by the phosphor are used for fluorescence emission, is an indicator that the internal quantum efficiency is apparently large in the region where the absorption rate of excitation light is low. It is also not easy to judge the quality of the phosphor based only on the internal quantum efficiency evaluation results.
• the double fluoride phosphor obtained by the above manufacturing method can have an absorption rate of 455 nm light of, for example, 80% or more, 85% or more, 87% or more, or 89% or more.
• the above-mentioned double fluoride phosphor has an absorption rate of 85% or more for light at 455 nm and can exhibit excellent internal quantum efficiency.
• the internal quantum efficiency of the double fluoride phosphor can be, for example, 80% or more, 82% or more, 84% or more, or 85% or more.
• Absorption rate and internal quantum efficiency in this specification mean absorption rate and fluorescence quantum efficiency obtained when excited using light with a wavelength of 455 nm. More specifically, it is determined by measuring according to the method described in the Examples of this specification.
• the above-mentioned double fluoride phosphor is useful as a red phosphor because it can emit fluorescence having a peak around 630 nm when excited using blue light with a wavelength of 455 nm.
• the above-mentioned double fluoride phosphor may be used alone or in combination with other phosphors.
• the above-mentioned double fluoride phosphor has excellent absorption rate and internal quantum efficiency, it can be suitably used for, for example, light-emitting devices such as LEDs, display devices, and the like.
• the above-mentioned double fluoride phosphor may be used by being dispersed in a cured resin.
• the cured resin in this case is not particularly limited, and for example, a resin used as a sealing resin for light emitting devices and the like can be used.
• An example of a light emitting device is a light emitting device that includes a light emitting element that emits primary light and a wavelength converter that absorbs a portion of the primary light and emits secondary light having a wavelength longer than the wavelength of the primary light.
• the wavelength converter includes the double fluoride phosphor.
• the light emitting element that emits primary light may be, for example, an InGaN blue LED.
• the light emitting element and wavelength converter may be dispersed in a sealing resin or the like.
• Example 1 A double fluoride phosphor represented by K 2 SiF 6 :Mn was manufactured by the method shown below.
• silica SiO 2 , manufactured by Denka Co., Ltd., trade name: FB-50R, amorphous, average particle size: 55 ⁇ m
• KMF potassium hexafluoromanganate
• the aqueous solution was stirred for a while to complete precipitation of yellow powder. Thereafter, the aqueous solution was allowed to stand still to precipitate the solid content. After confirming the precipitation, remove the supernatant liquid, wash the yellow powder using hydrofluoric acid and methanol with a concentration of 20% by mass, filter it to separate and recover the solid matter, and further dry it. Residual methanol was removed by evaporation. After the drying treatment, using a nylon sieve with an opening of 75 ⁇ m, only the yellow powder that passed through the sieve was classified and collected to finally obtain yellow powder. By performing X-ray diffraction measurement on the obtained yellow powder, it was confirmed that the powder was a double fluoride phosphor having a composition represented by K 2 SiF 6 :Mn 4+ .
• Example 2 As shown in Table 1, a double fluoride phosphor was prepared in the same manner as in Example 1, except that the amount of K 2 MnF 6 was adjusted and the ratio of the amount of manganese material to the amount of silicon material was changed. Prepared.
• a concave cell was filled with a double fluoride phosphor to be measured so that the surface was smooth, and the cell was attached to the opening of an integrating sphere.
• Monochromatic light separated into wavelengths of 455 nm from a Xe lamp as a light emitting light source was introduced into the integrating sphere as excitation light for the phosphor using an optical fiber. This monochromatic excitation light was irradiated onto the fluoride phosphor to be measured, and the fluorescence spectrum was measured.
• a spectrophotometer manufactured by Otsuka Electronics Co., Ltd., trade name: MCPD-7000 was used for the measurement.
• the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated.
• the number of excitation reflected light photons was calculated in the same wavelength range as the number of excitation light photons, and the number of fluorescence photons was calculated in the range of 465 to 800 nm.
• a standard reflector having a reflectance of 99% (Spectralon (registered trademark), manufactured by Labsphere) was attached to the aperture of the integrating sphere, and the spectrum of excitation light having a wavelength of 455 nm was measured. At that time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.

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• 2023
  • 2023-03-06 JP JP2024507768A patent/JPWO2023176559A1/ja not_active Withdrawn
  • 2023-03-06 WO PCT/JP2023/008404 patent/WO2023176559A1/ja not_active Ceased

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