WO2018003848A1 - 蛍光体及び発光装置 - Google Patents
蛍光体及び発光装置 Download PDFInfo
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- WO2018003848A1 WO2018003848A1 PCT/JP2017/023735 JP2017023735W WO2018003848A1 WO 2018003848 A1 WO2018003848 A1 WO 2018003848A1 JP 2017023735 W JP2017023735 W JP 2017023735W WO 2018003848 A1 WO2018003848 A1 WO 2018003848A1
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- sialon phosphor
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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
- C09K11/77—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing rare earth metals
- C09K11/7728—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing rare earth metals containing europium
- C09K11/77348—Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
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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
- C09K11/55—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing beryllium, magnesium, alkali metals or alkaline earth metals
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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
- C09K11/64—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing aluminium
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
- H10H20/80—Constructional details
- H10H20/85—Packages
- H10H20/851—Wavelength conversion means
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
- H10H20/80—Constructional details
- H10H20/85—Packages
- H10H20/851—Wavelength conversion means
- H10H20/8511—Wavelength conversion means characterised by their material, e.g. binder
- H10H20/8512—Wavelength conversion materials
Definitions
- the present invention relates to a Li- ⁇ sialon phosphor, a light emitting element including the phosphor and a light emitting source, and a light emitting device including the light emitting element.
- a white LED generally has a structure in which, for example, a blue LED serving as a light emitting light source is sealed with a sealing material such as a resin containing a phosphor, but the phosphor is usually a yellow phosphor. Or a combination of a red phosphor and a green phosphor, which are finely dispersed in a resin to be sealed.
- red phosphors used in white LEDs include ⁇ sialon phosphors.
- the phosphor base crystal which has become totally destabilized by dissolving the activator element for light emission as the ⁇ sialon phosphor referred to as the light activator element
- the ⁇ sialon phosphor crystal the phosphor base crystal which has become totally destabilized by dissolving the activator element for light emission as the ⁇ sialon phosphor (referred to as the light activator element), that is, the ⁇ sialon phosphor crystal
- Ca 2+ is further included in a part of the inner space to stabilize the base crystal, for example, represented by the general formula: Ca x Eu y Si 12- (m + n) Al (m + n) OnN 16-n
- a Ca- ⁇ sialon phosphor is known.
- the Li- ⁇ sialon phosphor has improved brightness and has a shorter wavelength than the Ca- ⁇ sialon phosphor.
- a light emitting device using the Li- ⁇ sialon phosphor emits light when used for a long time. Another problem that has not been seen in a light emitting device using a Ca- ⁇ sialon phosphor, in which the luminance of the device decreases with time, has been sought.
- An object of the present invention is to provide a Li- ⁇ sialon phosphor that is small in luminance with time and has excellent long-term stability, a light-emitting element using the Li- ⁇ sialon phosphor, and a light-emitting device including the light-emitting element Is to provide.
- the present inventors have found that water molecules existing in the vicinity of the surface of the Li- ⁇ sialon phosphor (in the present application, the vicinity of the surface and the surface may be collectively referred to as the surface), the nature of the OH group bonded to the surface, As a result of investigating the influence of the existence ratio on the change with time of the luminance of the light emitting device using the Li- ⁇ sialon phosphor, it is difficult to detach from the Li- ⁇ sialon phosphor even in a high temperature environment. It has been found that the higher the proportion of OH groups (referred to as stable OH groups) that are stably bonded to the surface, the less the luminance decreases with time, and the present invention has been completed.
- the present invention (1) A Li- ⁇ sialon phosphor containing a light-emitting activation element in which stable OH groups are bonded to the phosphor surface at a ratio of 10 / nm 2 or more. (2) It is preferable that the light emitting activation element contained in the Li- ⁇ sialon phosphor is Eu. (3) The Li content of the Li- ⁇ sialon phosphor is preferably 1.8% by mass or more and 3.0% by mass or less. (4) The Eu content in the Li- ⁇ sialon phosphor is preferably 0.1% by mass or more and 1.5% by mass or less. (5) The oxygen content of the Li- ⁇ sialon phosphor is preferably 0.4% by mass or more and 1.3% by mass or less.
- a light-emitting device comprising the Li- ⁇ sialon phosphor according to any one of (1) to (5) and a light-emitting light source that irradiates the phosphor with excitation light.
- the light emission source of the said light emitting element is a light emitting diode or a laser diode.
- a light-emitting element including a Li- ⁇ sialon phosphor having a small decrease in luminance with time and improved long-term stability, and further provides a light-emitting device using the light-emitting element. I was able to do it.
- Li- ⁇ sialon phosphor containing a light-emitting activation element in which stable OH groups are bonded to the phosphor surface at a ratio of 10 / nm 2 or more.
- Li is lithium
- element A is a light-emitting active element.
- one or more selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb Si represents silicon, Al represents aluminum, O represents oxygen, and N represents nitrogen.
- Li and the element A are further added so that a part of the Si—N bond of the ⁇ -silicon nitride crystal is replaced by an Al—N bond and an Al—O bond, and electrical neutrality is maintained.
- the m value and the n value in the general formula correspond to the substitution rate to the Al—N bond and Al—O bond, respectively.
- the range of the m value that can maintain the entire structure is 0.5 or more and 2 or less
- the range of the n value is 0 or more and 0.5 or less.
- the moisture adsorbed or bound to the surface of the Li- ⁇ sialon phosphor is defined as follows. That is, when the Li- ⁇ sialon phosphor is heated under atmospheric pressure, moisture desorbed at a heating temperature of less than 200 ° C. is “physically adsorbed water”, and moisture desorbed at a heating temperature of less than 400 ° C. Of these, moisture excluding “physically adsorbed water” is referred to as “unstable OH group”, and moisture that does not desorb unless the phosphor is heated to 400 ° C.
- stable OH group is an OH group which is measured after desorption from the phosphor surface for the first time when the temperature of the phosphor sample is set to 400 ° C. or higher in the moisture analysis by the Karl Fischer method. It should be noted that the Li- ⁇ sialon phosphor of the present invention only needs to satisfy the provision relating to the proportion of stable OH groups.
- “stable OH groups are bonded at a ratio of 10 / nm 2 or more” means that the calculated value of the stable OH groups, for example, by moisture analysis by the Karl Fischer method is 1 nm 2 . It means 10 or more per unit area.
- the proportion of stable OH groups is less than 10 / nm 2 , the adhesion between the phosphor and the sealing material in the light-emitting element becomes insufficient, and the luminance tends to decrease with time.
- the proportion of stable OH groups is at least 10 / nm 2 or more, preferably 25 / nm 2 or more, more preferably 30 / nm 2 or more, and even more preferably. is 35 / nm 2 or more.
- the Li- ⁇ sialon phosphor of the present invention includes a raw material mixing step in which various phosphor raw materials are mixed to form a mixed raw material, a firing step in which the mixed raw material is mainly fired to obtain a Li- ⁇ sialon phosphor, and as necessary.
- the pulverization step for pulverizing or pulverizing the fired body obtained in the calcination step, the acid treatment step for removing impurities and the like by immersing in an acid solution, as necessary The size is classified, and the Li- ⁇ sialon phosphor is further reheated under atmospheric pressure at a temperature lower than the temperature of the firing step to adjust the abundance of stable OH groups. can do.
- the proportion of stable OH groups in the Li- ⁇ sialon phosphor of the present invention can be increased by a heat treatment step.
- the mass ratio of Li based on the Li- ⁇ sialon phosphor including various impurities immediately after the firing step is preferably 1.8% by mass or more and 3.0% by mass or less.
- the Li content can be adjusted by blending the raw materials of the phosphor. Specifically, it can be adjusted by increasing or decreasing the compounding ratio of lithium nitride or lithium oxide as a Li-containing raw material.
- Li- ⁇ sialon phosphor of the present invention for the purpose of fine adjustment of fluorescence characteristics, a part of Li in the general formula is replaced with Mg, Ca, Y and lanthanide elements (excluding La, Ce and Eu). Substitution with one or more substitution elements selected from the group consisting of may be performed while maintaining electrical neutrality. Therefore, in one embodiment of the Li- ⁇ sialon phosphor of the present invention, Li is partially substituted by one or more of such substitution elements.
- a light emission activation element one or more elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb can be selected. Among these, Eu is preferable. Used.
- the element A which is a light emitting activation element
- the luminance is 0.1% by mass or more and 1.5% by mass or less.
- the Eu content ratio can be adjusted by blending the raw materials of the phosphor. Specifically, it can be adjusted by increasing or decreasing the compounding ratio of the europium oxide and the europium nitride of the Eu-containing raw material.
- the oxygen content in the Li- ⁇ sialon phosphor of the present invention is related to the luminance, and is preferably 0.4% by mass or more and 1.3% by mass or less. If the oxygen content in the phosphor raw material is too small, less than 0.4% by mass, there is a tendency that it is difficult to obtain a phosphor with high brightness because there is little crystal grain growth in the firing step. If it exceeds 1.3% by mass, the fluorescence spectrum is broadened, and there is a tendency that sufficient luminance cannot be obtained.
- the Li- ⁇ sialon phosphor of the present invention is a phosphor containing ⁇ sialon as a base crystal and further containing elements such as Li and Eu in the ⁇ sialon, as long as the influence on the fluorescence characteristics is small. Further, it may contain a crystal phase such as silicon nitride, aluminum nitride, lithium silicon nitride and a solid solution thereof, which are formed as secondary products.
- the purity of the Li- ⁇ sialon phosphor is preferably higher, but is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 98% by mass or more.
- the upper limit value does not need to be set in particular, but can be substantially 99% by mass or less, for example.
- the purity of the Li- ⁇ sialon phosphor is the ratio of crystal phases identified by powder X-ray diffraction (also referred to as XRD) using CuK ⁇ rays using an X-ray diffractometer (eg, Ultimate IV manufactured by Rigaku Corporation). It can ask for.
- the compound as a raw material for the Li- ⁇ sialon phosphor of the present invention is a compound containing a Si source, an Al source, a Eu source, and a Li source.
- Specific examples include silicon nitride powder, aluminum nitride powder, europium oxide powder, and lithium nitride powder.
- Each raw material is preferably prepared in advance in a powder state.
- phosphor raw materials other than lithium nitride powder such as silicon nitride powder, aluminum nitride powder, and europium oxide powder
- mixing is preferably performed by wet mixing.
- the solvent used in the wet mixing for example, ethanol can be used.
- a premixed powder is obtained through solvent removal, drying and crushing.
- the premixed powder is further mixed with the lithium nitride powder at a desired ratio to obtain a raw material mixed powder.
- the premixed powder and the lithium nitride powder are preferably mixed in an inert gas atmosphere such as nitrogen in order to avoid hydrolysis.
- the crucible used for firing is preferably made of a material that is physically and chemically stable in a high-temperature atmosphere, and is preferably made of boron nitride, carbon, or a high melting point metal such as molybdenum or tantalum.
- the firing atmosphere is not particularly limited, but is usually performed in an inert gas atmosphere or a reducing gas atmosphere. Only one kind of inert gas or reducing gas may be used, or any two or more kinds of gases may be used in any combination ratio. Examples of the inert gas or reducing gas include hydrogen, nitrogen, argon, ammonia and the like, and nitrogen is preferably used.
- the pressure of the firing atmosphere is selected according to the firing temperature.
- the firing temperature is lower than 1650 ° C., the crystal defects and unreacted residual amount of the base crystal increase, and if it exceeds 1900 ° C., the base crystal is decomposed, which is not preferable. Therefore, the firing temperature is preferably 1650 to 1900 ° C. If the firing time is short, there are many crystal defects and unreacted residual amount of the base crystal, and if the firing time is long, it is not preferable in view of industrial productivity. Therefore, it is preferably 2 to 24 hours.
- the Li- ⁇ sialon phosphor obtained in the firing step may be crushed or classified so as to have a desired particle size as required in the subsequent operation.
- the Li- ⁇ sialon phosphor immediately after being obtained in the firing step generally has a crystal ratio of the phosphor that is not sufficiently high, and it is difficult to express desired fluorescence characteristics as it is.
- the crystal ratio of the Li- ⁇ sialon phosphor can be increased by acid treatment with a mixed solution of hydrogen acid and nitric acid.
- the Li- ⁇ sialon phosphor of the present invention is usually used in the form of fine particles because it is finely dispersed in a sealing resin of a light emitting device, but the particle size of the Li- ⁇ sialon phosphor of the present invention is excessive. If it is too small, the fluorescence intensity tends to be low, and if it is too large, the LED sealed with a resin containing a phosphor or the like tends to vary in chromaticity of the emitted color or cause uneven color of the emitted color.
- the average primary particle diameter of the Li- ⁇ sialon phosphor of the present invention expressed by volume-based median diameter (D50) by laser diffraction / scattering method is preferably 7 ⁇ m or more and 35 ⁇ m or less. Therefore, in order to obtain a phosphor having high luminance and causing no color unevenness, it is preferable to further provide a classification step after acid treatment of the appropriately crushed Li- ⁇ sialon phosphor of the present invention to remove fine powder. . Either a wet method or a dry method may be employed for the classification step.
- the Li- ⁇ sialon phosphor after acid treatment is mixed in a mixed solvent of ion-exchanged water and sodium hexametaphosphate as a dispersant.
- water tank classification that uses a difference in sedimentation speed after standing by dispersion in a mixed basic solvent of ion-exchanged water and ammonia water and a difference in particle diameter, or dry classification using a sieve.
- the crystal ratio of the generally effective Li- ⁇ sialon phosphor can be increased, so that a phosphor with high luminous efficiency can be obtained.
- the luminance of the light emitting element decreases with time.
- the presence ratio of water molecules and OH groups present on or bound to the surface of the Li- ⁇ sialon phosphor affects the time-dependent change in luminance of the light-emitting element including the phosphor, and After finding as a new finding that the abundance ratio of OH groups (stable OH groups) that are stably bonded among the OH groups bonded to the surface of the Li- ⁇ sialon phosphor can be adjusted,
- the present invention has led to the invention of a Li- ⁇ sialon phosphor that is less likely to cause a decrease in luminance over time.
- the Li- ⁇ sialon phosphor In order to obtain a Li- ⁇ sialon phosphor that can provide a light-emitting element with a small decrease in luminance with time and excellent long-term stability, a stable OH group that is not easily detached from the Li- ⁇ sialon phosphor even under a high temperature environment
- the existence ratio may be 10 pieces / nm 2 or more.
- the Li- ⁇ sialon phosphor is preferably heat-treated.
- the atmosphere for the heat treatment is not particularly limited, but an atmosphere of air, nitrogen and hydrogen is preferable, and an air atmosphere is particularly preferable.
- the heat treatment temperature in the case of heat treatment is preferably 1000 ° C. or less, and preferably 700 ° C.
- the minimum of heat processing temperature is 100 degreeC or more, It is more preferable that it is 200 degreeC or more, It is still more preferable that it is 400 degreeC or more.
- the heat treatment temperature is 1000 ° C. or higher, the Li- ⁇ sialon phosphor itself deteriorates in characteristics, resulting in a decrease in luminance.
- the proportion of stable OH groups can be adjusted by adjusting the holding time.
- the time for heat treatment of the Li- ⁇ sialon phosphor is preferably 3 hours or more, although depending on the heating temperature, and preferably less than 20 hours in view of mass production efficiency.
- the existence ratio of the stable OH groups stably bonded to the surface of the Li- ⁇ sialon phosphor may be 10 / nm 2 or more, and the heating temperature and the holding time are not particularly limited. .
- the second embodiment of the present invention is a light emitting device having the Li- ⁇ sialon phosphor and the light emission source according to the first embodiment of the present invention.
- the light emitting light source is preferably a monochromatic LED or LD having an emission peak wavelength of 240 nm or more and 480 nm or less.
- Monochromatic light having a light source peak wavelength of 240 nm or more and 480 nm or less is also the peak wavelength region of the most commonly used blue LED, and the Li- ⁇ sialon phosphor is efficiently excited by light having a wavelength in the above range. This is because light is emitted with luminance.
- a light emitting device including the Li- ⁇ sialon phosphor of the present invention and a light emitting light source can be manufactured, for example, as follows.
- the phosphor of the present invention is mixed with a sealing material to prepare a slurry.
- the slurry can be adjusted by mixing at a ratio of 30 to 50 parts by mass with respect to 100 parts by mass of the sealing material.
- the sealing material include thermoplastic resins, thermosetting resins, and photocurable resins.
- methacrylic resin such as polymethylmethacrylate
- styrene resin such as polystyrene and styrene-acrylonitrile copolymer
- polycarbonate resin polyester resin
- phenoxy resin butyral resin
- polyvinyl alcohol Cellulose resins such as cellulose acetate butyrate
- epoxy resins epoxy resins
- phenol resins silicone resins.
- inorganic materials such as metal alkoxides, ceramic precursor polymers or solutions containing metal alkoxides are hydrolyzed by a sol-gel method or a combination thereof, and solidified inorganic materials such as siloxane bonds. It is also possible to use an inorganic material.
- a melt-processed glass can be used as long as it is a sealing part that can be attached externally without directly touching the LED chip (for example, an external cap, a dome-shaped sealing part).
- a sealing material may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
- the sealing materials it is preferable to use a resin having thermosetting properties and fluidity at room temperature for reasons of dispersibility and moldability.
- a resin having thermosetting properties and fluidity at room temperature for example, a silicone resin is used.
- trade names: JCR6175, OE6631, OE6635, OE6636, OE6650, etc., manufactured by Toray Dow Corning Co., Ltd. can be mentioned.
- 3 to 4 ⁇ L of the slurry is injected into a top view type package in which a blue LED chip having an emission peak wavelength at 460 nm is mounted.
- the top view type package into which this slurry has been injected is heated at a temperature in the range of 140 to 160 ° C. for a period of 2 to 2.5 hours to cure the slurry.
- a light-emitting element that absorbs light in the wavelength range of 420 to 480 nm and emits light having a wavelength of more than 480 nm and not more than 800 nm can be manufactured.
- a blue light-emitting diode A light-emitting element sample that combines a phosphor and a phosphor is actually produced, and the light-emitting element sample is subjected to an energization test while being left in a high-temperature and high-humidity environment. It can be evaluated by the luminous flux retention rate (%) obtained from the total luminous flux measurement value. Since the luminous flux value immediately after the start of the energization test is used as a reference, the luminous flux retention after a predetermined time is desirably close to 100%.
- a third embodiment of the present invention is a light emitting device including the light emitting element. More specific examples of the light emitting device referred to in the present invention include a device for displaying information such as a traffic light and a display device, a headlight for a vehicle such as an automobile, an illumination device replacing an incandescent lamp and a fluorescent lamp.
- Example which concerns on this invention is described using a table
- Example 1 A method for manufacturing the phosphor of Example 1 will be described. The phosphor was manufactured through a raw material mixing step and a firing step.
- the raw material of the phosphor of Example 1 is Si 3 N 4 (E10 grade made by Ube Industries), AlN (F grade made by Tokuyama Corp.), Eu 2 O 3 (RU grade made by Shin-Etsu Chemical Co., Ltd.), Li 3 N powder (Purity 99.5% by mass, -60 mesh, manufactured by Material).
- the raw material mixed powder is filled in a boron nitride crucible in a glove box, and baked at 1800 ° C. for 8 hours in a nitrogen atmosphere with a gauge pressure of 0.8 MPa in an electric furnace of a carbon heater. -Obtained ⁇ -sialon phosphor.
- the Eu-activated Li- ⁇ sialon phosphor after the classification is immersed in a mixture (80 ° C.) of hydrofluoric acid and nitric acid of at least 300 mL with respect to 100 g of the phosphor. Processed.
- the Li- ⁇ sialon phosphor after the classification step is filled into a magnetic crucible, and is heated in an electric furnace at 200 ° C. for 3 hours in an air atmosphere.
- the Eu-activated Li- ⁇ sialon of the present invention shown in Example 1 is used. Got.
- Example 2 The Eu-activated Li- ⁇ sialon of Example 2 was obtained by carrying out the same manufacturing method as in Example 1 except that the heat treatment step was performed at 500 ° C. for 3 hours in the atmosphere.
- Example 3 The Eu-activated Li- ⁇ sialon of Example 3 was obtained by carrying out the same manufacturing method as in Example 1 except that the heat treatment step was performed at 700 ° C. for 3 hours in the atmosphere.
- Example 4 The Eu-activated Li- ⁇ sialon of Example 4 was obtained by carrying out the same production method as in Example 1 except that the atmospheric heating step was performed at 1100 ° C. in the atmosphere for 3 hours.
- the phosphors according to Examples 1 to 4 and Comparative Examples 1 and 2 were mixed at a ratio of 30 parts by mass with respect to 100 parts by mass of a silicone resin (manufactured by Toray Dow Corning Co., Ltd., trade name: JCR6175, etc.). The slurry was adjusted. Thereafter, 3 to 4 ⁇ L of the slurry was injected into a top view type package on which a blue LED chip having a peak wavelength at 460 nm was mounted. The top view type package into which this slurry was injected was heated at 150 ° C. for 2 hours to cure the slurry, and a light emitting device rated at 150 mA as a sample was manufactured.
- a silicone resin manufactured by Toray Dow Corning Co., Ltd., trade name: JCR6175, etc.
- Table 1 shows a simple comparison and evaluation results of the phosphors according to Examples 1 to 4 and Comparative Examples 1 and 2 (the above are collectively referred to as Examples).
- Table 1 shows the presence or absence of the acid treatment step and the classification step, the temperature of the heat treatment step, the ratio of stable OH groups (unit: units / nm 2 ), the peak wavelength (unit: nm), and the median for the examples. It shows the diameter (unit: ⁇ m), the ratio of ⁇ sialon crystals to the entire crystal phase (unit:%), the fluorescence intensity (unit:%), and the luminous flux retention rate (unit:%) of the LED.
- the quantification of stable OH groups in the present invention was carried out using the Karl Fischer method.
- the Karl Fischer measurement uses a moisture vaporizer VA-122 manufactured by Mitsubishi Chemical Corporation and a moisture analyzer CA-100 manufactured by Mitsubishi Chemical Corporation.
- Aquamicron AX manufactured by Mitsubishi Chemical Corporation
- the catholyte is used as the anolyte.
- Used Aquamicron CXU Mitsubishi Chemical Corporation.
- the background value was fixed at 0.10 ( ⁇ g / sec), and the measurement was continued until the detected water content fell below the background value. The measurement was performed at 550 ° C.
- the phosphor sample was not exposed to the outside air, and the water generated from the water vaporizer was introduced into the Karl Fischer device along with 300 ml / min of high-purity argon, and the water content was measured.
- the sample introduced into the moisture vaporizer was 4 g.
- the specific surface area was measured using an AUTOMATIC SURFACE ANALYZER MODEL-4232-2 (Roman numerals) manufactured by Microdata.
- the median diameter (D50) (average primary particle diameter) of each phosphor according to Examples and Comparative Examples was measured as follows. First, a mixture of hydrofluoric acid (concentration in the range of 46 to 48 g / 100 ml) and nitric acid (concentration 60 g / 100 ml) at a ratio of 1: 1 was diluted 4 times with distilled water to prepare a treatment solution. While heating this processing liquid to 80 degreeC and stirring, the fluorescent substance of an Example or a comparative example was added and disperse
- the recovered insoluble powder was washed with water and dried.
- the particle size distribution was measured with a laser diffraction scattering type particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter, Inc.), and the 50% cumulative particle size based on volume was determined as the median diameter (D50). It was.
- a spectrofluorometer (F-7000, manufactured by Hitachi High-Technologies Corporation) corrected with rhodamine B and a sub-standard light source was used, and a solid sample holder attached to the photometer was attached. Used to measure the fluorescence spectrum and peak wavelength at an excitation wavelength of 455 nm.
- the fluorescence intensity was calculated from the product of fluorescence spectrum intensity and CIE standard relative luminous efficiency. In addition, since it changes with measuring apparatuses and conditions, a unit is arbitrary and it compared by the relative in the Example and comparative example which were measured on the same conditions. As a reference, the fluorescence intensity of Example 1 was set to 100%. In addition, a fluorescence intensity is a pass value if it shows 85% or more.
- the measurement of the change of the total luminous flux is, for example, the environment and durability test method (life test 1 (Roman numeral)) of a semiconductor device standard JEITA ED-4701 / 100A semiconductor device, high temperature and high humidity bias test, test method
- a light-emitting element sample with a rated current of 150 mA combining a blue light-emitting diode and a phosphor is manufactured, and the light is emitted under conditions of a current of 150 mA at a temperature of 85 ° C. and a relative humidity of 85 RH%.
- the luminous flux retention after 1000 hours is preferably 95% or more.
- the total luminous flux measurement system (Half Moon: Otsuka Electronics HH41-0773-1) was used to measure the luminous flux emitted from the light emitting element sample.
- Li-alpha SiAlON phosphor of Examples 1-4 by the existing ratio of stable OH groups are many 10 / nm 2 or more and compared with the comparative example, the ratio of alpha-sialon crystal was high. As a result, a high intensity of fluorescence was obtained, and even when used for a long time, the light emission efficiency was small and the light emitting device had few electrical defects. Since the light emitting devices using the phosphors according to Examples 1 to 4 have many stable OH groups, there is very little possibility of causing an electrical abnormality such as a short circuit by increasing the adhesiveness with the resin, and a long lifetime.
- the luminous flux maintenance factor is high like the Li- ⁇ sialon phosphors of Examples 1 to 3, but the temperature in the heat treatment step is high. Therefore, the luminous efficiency of the phosphor tended to decrease slightly.
- Comparative Example 1 had a small amount of stable OH groups and a low proportion of Li- ⁇ sialon crystals, so that the fluorescence intensity was low and the luminous flux maintenance factor was also lowered.
- Comparative Example 2 is a reproduction of Li- ⁇ sialon phosphors up to the range of the prior art, and since the proportion of Li- ⁇ sialon crystals is high, the fluorescence intensity is high, but there are few stable OH groups, and the light flux is maintained. The rate was low and the long-term stability was poor.
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Abstract
Description
(1)蛍光体表面に、安定OH基が10個/nm2以上の存在割合で結合している、発光付活元素を含むLi-αサイアロン蛍光体である。
(2)前記Li-αサイアロン蛍光体に含まれる発光付活元素は、Euであるであることが好ましい。
(3)前記Li-αサイアロン蛍光体の、Li含有割合は1.8質量%以上3.0質量%以下であることが好ましい。
(4)前記Li-αサイアロン蛍光体の、Eu含有割合は0.1質量%以上1.5質量%以下であることが好ましい。
(5)前記Li-αサイアロン蛍光体の、酸素含有割合は0.4質量%以上1.3質量%以下であることが好ましい。
(6)前記(1)~(5)のいずれかひとつに記載のLi-αサイアロン蛍光体と、前記蛍光体に励起光を照射する発光光源とを有する、発光素子である。
(7)前記発光素子の発光光源が、発光ダイオード又はレーザーダイオードであることが好ましい。
(8)前記(6)または(7)記載の発光素子を備える、発光装置である。
実施例1の蛍光体の製造方法について説明する。蛍光体は、原料の混合工程、焼成工程を経ることによって製造した。
実施例1の蛍光体の原料は、Si3N4(宇部興産社製E10グレード)、AlN(トクヤマ社製Fグレード)、Eu2O3(信越化学工業社製RUグレード)、Li3N粉末(Materion社製純度99.5質量%、-60mesh)である。まず、Si3N4:AlN:Eu2O3=84.5:14.8:0.64のmol比となる様に秤量し、混合して予混合粉末を得た。
前記原料混合粉末をグローブボックス内で窒化ホウ素質の坩堝に充填し、カーボンヒーターの電気炉で、ゲージ圧0.8MPaの加圧窒素雰囲気中、1800℃で8時間焼成を行い、Eu付活Li-αサイアロン蛍光体を得た。
なお、焼成後の前記Eu付活Li-αサイアロン蛍光体は粒子形状が大きく、塊状であったため、ロールミル及びジェットミルによる乾式粉砕機により粉砕し、目開き45μm篩に押し当て通過させたものに選別した。
前記分級した後のEu付活Li-αサイアロン蛍光体に対しては、蛍光体100gに対して、少なくとも300mL以上のフッ化水素酸及び硝酸の混合液(80℃)中に浸漬することにより酸処理した。
酸処理工程後のLi-αサイアロン蛍光体200gを、イオン交換水と分散剤であるヘキサメタリン酸ナトリウムとの少なくとも2L以上の十分量の混合溶媒中で10分間静置することにより、5μm以下の微粉を取り除いた。
分級工程後のLi-αサイアロン蛍光体を磁性坩堝に充填し、電気炉で、大気雰囲気中200℃で3時間の加熱処理を行い、実施例1に示す本発明のEu付活Li-αサイアロンを得た。
実施例2のEu付活Li-αサイアロンは、加熱処理工程の条件を大気中500℃で3時間のアニールとした以外は、実施例1と同様の製造方法を実施することにより得た。
実施例3のEu付活Li-αサイアロンは、加熱処理工程の条件を大気中700℃で3時間のアニールとした以外は、実施例1と同様の製造方法を実施することにより得た。
実施例4のEu付活Li-αサイアロンは、大気加熱工程の条件を大気中1100℃で3時間のアニールとした以外は、実施例1と同様の製造方法を実施することにより得た。
比較例1のEu付活Li-αサイアロンは、実施例1の製造工程で、酸処理工程と分級工程、加熱処理工程を省略した以外は、実施例1と同様の製造方法によって得た。
比較例2のEu付活Li-αサイアロンは、実施例1の製造工程で加熱処理工程を省略した以外は、実施例1と同様の製造方法によって得た。
実施例1~4及び比較例1、2に係る各蛍光体を、シリコーン樹脂(東レ・ダウコーニング株式会社製、商品名:JCR6175など)100質量部に対して30質量部の割合で混合して、スラリーを調整した。その後、460nmにピーク波長を有する青色LEDチップが実装されたトップビュータイプパッケージに、上記スラリー3~4μLを注入した。このスラリーが注入されたトップビュータイプパッケージを150℃にて2時間の範囲で加熱し、スラリーを硬化させ、サンプルとなる定格150mAの発光素子を製造した。
実施例等に係る各蛍光体について、X線回折装置(株式会社リガク社製UltimaIV)を用い、CuKα線を用いた粉末X線回折(XRD)により、結晶相を同定した。実施例1~4、比較例1、2にて得られた蛍光体のX線回折パターンは、Li―αサイアロン結晶と同一の回折パターンが認められ、主結晶相がLi―αサイアロンであることが確認された。
本発明における安定OH基の定量はカールフィッシャー法を用いて行った。カールフィッシャー測定は三菱化学社製水分気化装置VA-122と三菱化学社製水分測定装置CA-100を使用し、水分測定装置の陽極液にはアクアミクロンAX(三菱化学社製)、陰極液にはアクアミクロンCXU(三菱化学社製)を使用した。カールフィッシャー測定に際してはバックグラウンド値を0.10(μg/sec)に固定し、検出される水分がバックグラウンド値を下回るまで継続して測定を行った。測定は550℃で実施した。加熱処理時は蛍光体サンプルを外気にさらさないようにし、水分気化装置から発生した水分を高純度アルゴン300ml/minに同伴させカールフィッシャー装置に導入し、水分量を測定した。水分気化装置に導入するサンプルを4gで行った。
カールフィッシャー測定において検出される水分は、OH基2個が縮合して1個の水分子になると考えられるため、単位面積あたりのOH基の数は、
単位面積あたりのOH基の数(個/nm2)=0.0668×水分量(ppm)/蛍光体サンプルの比表面積(m2/g)
の式により算出する。なお、前記式の係数である0.0668は、左辺と右辺の単位を揃えるための係数である。
比表面積測定はマイクロデータ社製AUTO MATIC SURFACE ANALYZER MODEL-4232-2(ローマ数字)を使用して行った。
実施例及び比較例に係る各蛍光体のメジアン径(D50)(平均一次粒子径)を、以下の要領で測定した。先ず、フッ化水素酸(濃度46~48g/100mlの範囲)と硝酸(濃度60g/100ml)を1:1で混合したものを、蒸留水で4倍に希釈して、処理液を作製した。この処理液を、80℃に加熱し、撹拌しながら、実施例又は比較例の蛍光体を、処理液100mlに対して20g以下の量添加し、分散させた。蛍光体を分散後1時間放置し、デカンテーションにより不溶粉末を回収した。回収した不溶粉末を、水洗し、乾燥させた。乾燥後の不溶粉末について、レーザー回折散乱式粒度分布測定装置(ベックマン・コールター株式会社製 LS 13 320)により粒子径分布を測定し、体積基準の累積50%の粒子径を、メジアン径(D50)とした。
蛍光強度は、蛍光スペクトル強度とCIE標準比視感度の積から算出した。なお、測定装置や条件によって変化するため単位は任意であり、同一条件で測定した実施例及び比較例での相対で比較した。基準として、実施例1の蛍光強度を100%とした。なお、蛍光強度は85%以上を示せば合格値である。
次に、実施例及び比較例に係る蛍光体粒子を備える発光素子について、全光束値の変化率を測定して、光束保持率を算出することにより使用時の長期安定性を評価した。全光束の変化の測定は、例えば、電子情報技術産業協会規格JEITA ED-4701/100A半導体デバイスの環境及び耐久性試験方法(寿命試験1(ローマ数字))の、高温高湿バイアス試験、試験方法102Aに準拠して、例えば青色発光ダイオードと蛍光体とを組み合わせた定格電流150mAの発光素子サンプルを作製し、温度85℃、85RH%の相対湿度下で、通電150mAの条件で発光させたまま1000時間放置する通電試験を実施し、試験開始直後の値を基準にした1000時間経過後の光束保持率(%)を、求めて評価することができる。1000時間経過後の光束保持率は95%以上であることが好ましい。光束は、全光束測定システム(Half Moon:大塚電子製HH41-0773-1)を用いて、発光素子サンプルから放出された蛍光の光束を測定した。
Claims (8)
- 蛍光体表面に、安定OH基が10個/nm2以上の存在割合で結合している、発光付活元素を含むLi-αサイアロン蛍光体。
- 発光付活元素がEuである、請求項1記載のLi-αサイアロン蛍光体。
- Li含有割合が1.8質量%以上3.0質量%以下である、請求項1または2記載のLi-αサイアロン蛍光体。
- Eu含有割合が0.1質量%以上1.5質量%以下である、請求項1~3いずれか一項記載のLi-αサイアロン蛍光体。
- 酸素含有割合が0.4質量%以上1.3質量%以下である請求項1~4のいずれか一項記載のLi-αサイアロン蛍光体。
- 請求項1~5のいずれか一項記載のLi-αサイアロン蛍光体と、前記蛍光体に励起光を照射する発光光源とを有する、発光素子。
- 発光光源が、発光ダイオード又はレーザーダイオードである、請求項6記載の発光素子。
- 請求項6または7記載の発光素子を備える、発光装置。
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| WO2019150910A1 (ja) * | 2018-02-02 | 2019-08-08 | デンカ株式会社 | β型サイアロン蛍光体及びその製造方法、並びに発光装置 |
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| JP7361968B1 (ja) * | 2023-03-31 | 2023-10-16 | デンカ株式会社 | α型サイアロン蛍光体、発光装置およびα型サイアロン蛍光体の製造方法 |
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