WO2011148910A1 - Eu賦活アルカリ土類金属シリケート蛍光体の製造方法 - Google Patents
Eu賦活アルカリ土類金属シリケート蛍光体の製造方法 Download PDFInfo
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- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
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- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
Definitions
- the present invention shows a yellow light of high luminance by photoexcitation in the visible range from ultraviolet, strontium silicate-based phosphors activated with Eu 2+ (composition formula (Sr 1-y, Eu y ) 3 SiO 5 ( where, 0 ⁇ Y ⁇ 0.1)), and a composition of formula (Ba x , Sr 1-xy , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1), composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1)
- the present invention relates to a method for producing an alkaline earth metal silicate phosphor activated with Eu 2+ .
- White LEDs are a mixture of LEDs that emit light from near ultraviolet to blue and phosphors to generate white light.
- white LEDs have been actively developed as LCD backlight sources for small portable devices.
- a phosphor for white LED used for this white LED YAG: Ce 3+ which shows yellow fluorescence by blue excitation or (Ba, Sr, Ca) 2 SiO 4 : Eu 2+ which shows green to yellow fluorescence.
- Sr 3 SiO 5 Eu 2+ and the like are known, but a phosphor with higher luminance is desired.
- a phosphor synthesis method is performed by mixing raw material powders in a wet or dry manner, placing them in a baking container, and baking and heating them at a high temperature. Synthesized by reaction.
- heat treatment is generally performed in a reducing atmosphere with an inert gas containing several percent of H 2 gas.
- Sr 3 SiO 5 : Eu 2+ SrO and SiO 2 react to form a host oxide crystal, and the activator Eu is reduced from trivalent to divalent by firing in a reducing atmosphere. Substituting Sr 2+ in the host crystal. Thereby, a Sr 3 SiO 5 : Eu 2+ phosphor can be synthesized.
- a liquid phase is used to produce a metal oxide precursor, and the precursor is fired to synthesize the metal oxide.
- the law is being considered.
- metal elements are dissolved and mixed in a solvent, so uniform mixing at the atomic level is possible, and it is not necessary to cause solid phase diffusion of oxide raw material powder as in the solid phase method, so at low temperatures. Synthesis is expected. Further, the increase in crystal particle diameter can be suppressed by low-temperature synthesis.
- Patent Document 1 An example of such a liquid phase method is a precipitation method disclosed in Patent Document 1.
- a precipitate is generated from a metal salt, tetraethoxysilane (TEOS) or silica gel, and a phosphor is synthesized by drying and heat treatment.
- TEOS tetraethoxysilane
- a phosphor is synthesized by drying and heat treatment.
- the metal salt and TEOS do not precipitate at the same time, but are only close to a finer state of the powder raw material described above, and are not uniformly mixed at the elemental level.
- Patent Document 2 as a liquid phase method, a precursor is obtained by wet synthesis such as a citric acid method, a coprecipitation method, a metal alkoxide method (sol-gel method), a thermal decomposition method, a complex polymerization method, a PVA method, or a hydrothermal gelation method.
- the method of producing a body is described, and it is described that the metal oxide phosphor can be efficiently synthesized by using the hydrothermal gelation method by comparing them.
- a mixed solution composed of one or more metal elements, TEOS and a solvent is hydrothermally treated, a gel body in which the metal elements are uniformly dispersed can be produced. The gel is dried and heat-treated.
- a composite metal oxide precursor is formed. Since this gel utilizes the gelling ability of TEOS, it is characterized by a small amount of organic matter. A uniform precursor can be produced by hydrothermal gelation of the liquid phase mixed at the atomic level. Since this precursor has a short element diffusion distance, a complex metal oxide having a uniform chemical composition can be formed by heat treatment at a relatively low temperature. However, since the gelation ability of TEOS is used, when the composition ratio of silicon in the metal component is small, the metal element component cannot be contained in the gel.
- silicon alkoxides such as TEOS are generally used also when the alkaline earth metal silicate phosphor precursor is produced by a liquid phase method other than the hydrothermal gelation method.
- a metal salt and TEOS as raw materials and dissolving them in a suitable solvent, a uniform gel can be produced.
- a non-aqueous solvent is used as the solvent, a uniform mixture can be prepared.
- water is used as the solvent, the hydrolysis reaction proceeds at the interface between TEOS and water because tetraethoxysilane is hydrophobic. There is a problem that the reaction may occur locally and it is difficult to obtain a homogeneous mixture.
- non-aqueous solvents in particular organic solvents, have a problem that they are harmful to human bodies and pose a risk of ignition.
- a water-soluble silicon compound which is a new silicon raw material is disclosed in Non-Patent Document 2 and Patent Document 3.
- This water-soluble silicon compound is obtained by substituting four ethoxy groups of TEOS with propyleneglycoxy groups, and has a hydroxyl group, and therefore can stably exist in an acidic aqueous solution at room temperature.
- the water-soluble silicon compound aqueous solution is hydrolyzed and polycondensed by heating or the like to obtain a SiO 2 gel.
- This water-soluble silicon compound is known to have a larger gelling ability than TEOS.
- Non-Patent Document 2 a water-soluble silicon compound is mixed with a metal zinc raw material aqueous solution, subjected to hydrothermal treatment to produce a precursor, and fired in a reducing atmosphere to obtain a Mn-added Zn 2 SiO 4 phosphor.
- This phosphor has a ratio of metal element (sum of Zn and Si) to Si of 3: 1, and it is difficult to gel all metal components with TEOS, but it contains all metal components by using a water-soluble silicon compound. A gel can be created.
- the hydrothermal synthesis method is indispensable for the preparation of the precursor, there is a problem that a heat treatment in a pressure vessel such as an autoclave is required.
- the present inventors have (Sr 1-y , Eu y ) 3 SiO 5 phosphor, (Ba x , Sr 1- xy ) having a ratio of metal component element to Si of 4: 1. , Eu y ) 3 SiO 5 , and (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 phosphors with a metal component element to Si ratio of 3: 1, and Eu-activated strontium
- a silicate phosphor precursor was tried by a hydrothermal gelation method using a water-soluble silicon compound. As a result, it has been found that it is difficult to contain all metal components uniformly and all in the gel, and compositional deviation and element distribution unevenness are likely to occur.
- the composition formula (Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1)
- the composition formula (Ba x , Sr 1-xy , Eu y ) 3 SiO 5 (
- the ratio of all metal component elements (Sr, Ba, Eu, Si) to Si is 4: 1 Eu-activated alkaline earth metal silicate phosphor, composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1)
- the ratio of all metal component elements (Ba, Sr, Eu, Si) and Si is 3: 1
- composition formula (Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1)
- the composition formula (Ba x , Sr). 1-xy , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1)
- composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 ( However, all metal components of strontium, barium, europium, and silicon, which are constituents of an alkaline earth metal silicate phosphor selected from the group of 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1), are used as an aqueous solution.
- the composition formula (Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1)
- the composition formula (Ba x , Sr 1-xy) , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1)
- composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (where 0 ⁇ X
- the process for producing an Eu-activated alkaline earth metal silicate phosphor selected from the group ⁇ 1, 0 ⁇ Y ⁇ 0.1) includes the following step 1.
- Step 1 By preparing an aqueous solution for each elemental raw material of the constituent metal components strontium, barium, europium, and silicon, and maintaining the mixed aqueous solution obtained by mixing the prepared aqueous solutions at a liquid temperature of 30 to 100 ° C., all metal components Forming a gel in which the total amount of is uniformly dispersed.
- the composition formula (Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1)
- the composition formula (Ba x , Sr 1-xy , Eu) y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1)
- composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (where 0 ⁇ X ⁇ 1 , 0 ⁇ Y ⁇ 0.1)
- the Eu-activated alkaline earth metal silicate phosphor production method includes the following steps 1 to 4.
- Step 1 By preparing an aqueous solution for each elemental raw material of strontium, barium, europium, and silicon that are constituent metal components, and maintaining the mixed aqueous solution obtained by mixing the prepared aqueous solutions at a liquid temperature of 30 to 100 ° C., all metal components Forming a gel in which the total amount of is uniformly dispersed.
- Step 2 A step of drying the gel formed in step 1 to form a dried product and removing a solvent contained therein.
- Step 3 A step of obtaining a calcined powder by heat-treating the dried product in step 2 in an air atmosphere to remove organic matter.
- Step 4 A step of heat-treating the calcined powder formed in step 3 under a reducing atmosphere to obtain a phosphor powder.
- the concentration of strontium, barium and europium as constituent metal components in the mixed aqueous solution in step 1 of the first or second invention is 1 to 5.5 mol / L.
- This is a method for producing an Eu-activated alkaline earth metal silicate phosphor.
- the aqueous solution of the silicon raw material in Step 1 of the first or second aspect is added to 1,2-propanediol to tetramethoxysilane and heated, stirred and mixed. Then, it is a manufacturing method of Eu activated alkaline-earth metal silicate fluorescent substance characterized by being the water-soluble silicon aqueous solution which added hydrochloric acid.
- the fifth invention according to the present invention includes a step of removing coarse particles having a size of 100 ⁇ m or more from the calcined powder formed in the step 3 by classification after the step 3 of the second invention. This is a method for producing an activated alkaline earth metal silicate phosphor.
- a composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (wherein the ratio of all metal component elements (Ba, Sr, Eu, Si) to Si is 3: 1) Eu-activated alkaline earth metal silicate phosphor with 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1, a composition formula in which the ratio of all metal component elements (Sr, Ba, Eu, Si) to Si is 4: 1 ( Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1), composition formula (Ba x , Sr 1-xy , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1 , 0 ⁇ Y ⁇ 0.1)
- FIG. 2 is a diagram showing an X-ray diffraction pattern of a sample of Example 1.
- FIG. It is a figure which shows the fluorescence spectrum of Example 1 and Example 6, and also showed commercially available YAG: Ce (spectrum of a prior art example) for the comparison. It is a figure which shows the fluorescence spectrum of Example 7 and Comparative Examples 8 and 9, and the commercially available YAG: Ce (the spectrum of a conventional example) was also shown for the comparison.
- the production process of the Eu-activated alkaline earth metal silicate phosphor of the present invention is an aqueous solution of elemental materials of constituent metal components strontium, barium, europium, and silicon (hereinafter also referred to as a raw material aqueous solution), After mixing, the silicon raw material is kept at a liquid temperature of 30 to 100 ° C. so that the silicon raw material is heated at a temperature of 30 to 100 ° C. and is transparent in a state where the entire amount including strontium, barium, and other metal components is uniformly dispersed.
- Step 1 for forming a simple gel Step 2 for obtaining a dried product from which the solvent has been removed by drying the transparent gel formed in Step 1, and then heat-treating the dried product in the air as a calcined powder
- step 3 of obtaining an Eu-activated alkaline earth metal silicate phosphor precursor, a step of classifying and removing coarse particles of 100 ⁇ m or more, if necessary, and a reducing atmosphere It is intended to include step 4 of forming a Eu-activated alkaline earth metal silicate phosphor by heat treatment in air.
- Step 1 In this process, raw material aqueous solutions of strontium, barium, europium, and silicon, which are constituent metal components, are mixed, held at a temperature of 30 to 100 ° C., and the total amount of all metal components of strontium, barium, europium, and silicon. Is a step of obtaining a gel in which is uniformly dispersed.
- a raw material aqueous solution of all metal components of strontium, barium, europium and silicon is prepared.
- the strontium raw material is not particularly limited as long as it is dissolved in water and the pH of the aqueous solution is 7 or less.
- Strontium chloride, oxide, acetate, nitrate, carbonate, sulfate, oxalate, etc. Can be used.
- Hydroxy carboxylic acids such as citric acid, lactic acid and malic acid may be added when the metal salt is dissolved.
- an aqueous carbonate solution having a lower solubility than nitrate.
- the barium raw material and the europium raw material are the same as the strontium raw material. Note that the raw material aqueous solutions of strontium, barium and europium may be prepared separately and mixed, or the mixed aqueous solution may be prepared in one container from the beginning.
- the above-mentioned known water-soluble silicon compound is used as a silicon raw material. If the pH of the aqueous solution is higher than 7, the water-soluble silicon compound immediately starts to gel, and a non-uniform gel body may be formed. Moreover, since it will be hard to gelatinize if it is smaller than pH 1, pH shall be the range of 1-7. Moreover, when there is too much water with respect to the metal element of a structural component, since a gel and a liquid will separate into two layers and a metal ion will elute to a liquid phase, there exists a possibility that a gel may become a non-uniform composition.
- the concentration of the metal element in the aqueous solution is 1 to 5.5 mol / L. Desirably, it is 2 to 5.5 mol / L.
- the specific production conditions of the water-soluble silicon compound can be produced by the method described in the production example of Patent Document 3. That is, 1,2-propanediol (0.4 mol) is added to tetramethoxysilane (0.1 mol), and stirred for 24 hours using a hot stirrer so that the liquid temperature becomes 54 ° C. After mixing, hydrochloric acid (0.0001 mol) is added, and the liquid temperature is further mixed at 54 ° C. for 1 hour to obtain a water-soluble silicon aqueous solution.
- Patent Document 3 describes a wide variety of water-soluble silicon compounds from Production Examples 1 to 9, all of which can be used in the present invention.
- the aqueous solutions prepared under the above conditions are mixed and stirred at room temperature for 30 minutes to 1 hour.
- the resulting solution is placed in a container and held at a temperature of 30 to 100 ° C. to obtain a uniform gel body.
- the temperature is lower than 30 ° C., it takes time for gelation, and when the temperature exceeds 100 ° C. and water boils, drying and gelation occur at the same time, so it is important that the temperature is 30 ° C. to 100 ° C. Further, the temperature is more preferably 50 to 100 ° C.
- the time for gelation is not particularly limited as long as the entire gel is uniformly gelled, and a uniform gel is usually obtained in about 24 hours.
- the container is not particularly limited, a container having heat resistance up to the heating temperature, such as glass, polypropylene, polytetrafluoroethylene, or the like can be used.
- Step 2 is a step of removing the solvent from the gel obtained in Step 1 to obtain a dried product.
- the removal of the solvent is simple by heating. Since the solvent component contained in the gel is water, ethanol or propylene glycol, it is preferably 100 to 120 ° C.
- the heating time depends on the amount of sample, but is preferably about 1 to 6 hours.
- step 3 the solid dry matter obtained in step 2 is heat-treated in the atmosphere to thermally decompose and remove organic matter, and further, a calcined powder that is a precursor of Eu-activated alkaline earth metal silicate phosphor is obtained. It is a process.
- the purpose of this heat treatment in the atmosphere is to decompose organic substances contained in the raw material, to remove carbon produced by the decomposition, and to carry out crystal growth of the oxide mother crystal of the Eu-activated alkaline earth metal silicate phosphor.
- the conditions for the heat treatment in the atmosphere are performed at a temperature of 400 to 1600 ° C.
- this heat treatment may be performed in a single heat treatment or may be performed in a plurality of times. However, when heat treatment is performed a plurality of times, it is desirable to perform crushing with a mortar or the like each time the heat treatment is performed. .
- the decomposition of the organic substance is to evaporate or thermally decompose and burn propylene glycol and hydroxycarboxylic acid contained in the raw material.
- a temperature of 400 or more is required in the atmosphere.
- the next carbon removal is to completely remove carbon generated in the above-described decomposition process of organic matter, and when the metal element is carbonated, it is decomposed. Carbon cannot be removed at a temperature lower than 700 ° C., and melting or sintering may occur when the temperature exceeds 1300 ° C. Therefore, heat treatment at a temperature higher than 1300 ° C. is performed in consideration of the heat treatment time. When removing carbon alone, heat treatment in a temperature range of 700 to 1300 ° C. is preferable.
- the oxide mother crystal is Sr 3 SiO 5
- the temperature ranges from 1300 ° C. to 1600 ° C. because it reacts with the alumina crucible at a temperature higher than 1600 ° C.
- Particularly preferred is 1450 ° C to 1550 ° C. If the heat treatment temperature is too low, an Sr 2 SiO 4 phase, which is a different phase, is generated as an impurity, and the emission intensity of the phosphor finally obtained is lowered, which is not preferable.
- the Sr 3 SiO 5 crystal is sintered or melted, making it difficult to obtain a powdered phosphor without pulverization. Crushing the phosphor damages the crystal and is not desirable for obtaining a high-luminance phosphor.
- this oxide mother crystal is (Ba x , Sr 1-x ) 3 SiO 5 , (Ba x , Sr 1-x ) 2 SiO 4 , it is difficult to obtain a crystal phase at a temperature lower than 1000 ° C., and 1600 ° C.
- a temperature range of 1000 ° C. to 1400 ° C. is preferred because it reacts with the alumina crucible at a temperature exceeding that. Especially preferably, it is 1200 to 1350 degreeC. If the heat treatment temperature is too low, similarly, a different phase of BaCO 3 phase or SrCO 3 phase remains as unreacted impurities, and the emission intensity of the phosphor finally obtained is lowered, which is not preferable.
- the heat treatment temperature is too high, the fired product is sintered or melted, and it is necessary to obtain a powdered phosphor by pulverization. Further, pulverizing the phosphor damages the crystal, which is not desirable for obtaining a high brightness phosphor.
- the heat treatment time is 1 to 24 hours, preferably 2 to 4 hours.
- the heat treatment time is short, the reaction for forming the base crystal becomes insufficient, the crystal phase purity is lowered, and the emission intensity is lowered.
- the heat treatment time is long, the sintering proceeds, and coarse particles that are hardly sintered are generated or fixed to the container.
- the above heat treatment may be performed multiple times, and may be performed by one heat treatment under the optimum conditions. Further, the heat treatment conditions may be changed to one suitable for each heat treatment. You may carry out by the heat processing cycle.
- the oxide mother crystal is Sr 3 SiO 5
- the Sr 2 SiO 4 phase which is a different phase
- Step 4 is a step in which the calcined powder obtained in Step 3 is heat-treated in a reducing atmosphere, and Eu 2+ is replaced with divalent strontium ions or divalent barium ions in the host crystal to obtain a phosphor.
- the calcined powder used here may be an oxide obtained by completely decomposing carbonate in Step 3, or may be a calcined powder partially containing carbonate.
- the temperature of the heat treatment (firing temperature) varies depending on the composition, firing conditions, sintering flux, etc., but when the oxide mother crystal is Sr 3 SiO 5 , it is 1300 to 1600 ° C., preferably 1450 to 1550 ° C. When the oxide mother crystal is (Ba x , Sr 1-x ) 3 SiO 5 , (Ba x , Sr 1-x ) 2 SiO 4 , it is 1000 to 1400 ° C., preferably 1000 to 1350 ° C.
- a gas in which 1 to 10 vol% of H 2 is mixed with an inert gas such as N 2 or Ar can be used.
- the Eu-activated alkaline earth metal silicate phosphor production method of the present invention comprises an alkaline earth silicate phosphor whose oxide mother crystal contains the composition formula Sr 2 SiO 4 and other alkaline earth metal elements in the composition. In the case of manufacturing, it can be considered and expected to be applicable.
- Identification and semi-quantification of the crystal phase of the prepared phosphor were performed by X-ray diffraction and Rietveld analysis.
- the composition deviation was evaluated by quantitative analysis by ICP emission analysis of each element.
- the emission characteristics were evaluated by measuring excitation and emission spectra using a fluorescence spectrophotometer FP-6500 (manufactured by JASCO Corporation). The emission spectrum was measured at an excitation light wavelength of 455 nm, and the excitation spectrum was measured at the peak wavelength of the emission spectrum.
- a citric acid (98.0%, manufactured by Wako Pure Chemical Industries, Ltd.) aqueous solution was weighed so that the total concentration of strontium and europium (hereinafter referred to as metal salt (Sr + Eu) aqueous solution concentration) was 4.0 mol / L.
- SrCO 3 was added and a clear solution was obtained by stirring at 40 ° C. for 1 hour. Further, the weighed Eu (NO 3 ) 3 ⁇ 6H 2 O was dissolved in water to obtain an aqueous solution.
- 1,2-propanediol (0.4 mol) is added to tetramethoxysilane (0.1 mol), and a hot stirrer is used so that the liquid temperature becomes 54 ° C. And mixed for 24 hours with stirring. Thereafter, hydrochloric acid (0.0001 mol) was added, mixed with a water-soluble silicon compound at a liquid temperature of 54 ° C., and mixed with the SrCO 3 solution and stirred for 30 minutes at room temperature to obtain a transparent mixed solution.
- the mixed solution prepared as described above was put in a polypropylene container, sealed with a cap, and kept at 50 ° C. for 24 hours to obtain a transparent gel. This gel had elasticity, but was in a uniform state from the appearance without being separated into two layers.
- Step 2 The transparent gel obtained in step 1 was kept in a dryer at 120 ° C. for 6 hours, the solvent in the gel was removed, and a dried gel was obtained. The dried gel was a transparent solid.
- Step 3 The dried gel obtained in step 2 was crushed in an agate mortar, heat-treated at 550 ° C. for 3 hours in the air atmosphere in an electric furnace, taken out and crushed, and then heat-treated again at 800 ° C. for 3 hours. . Further, after taking out and pulverizing, hold at 1200 ° C. for 3 hours, continue to heat up to 1500 ° C., hold for 3 hours, heat treatment in the air atmosphere, take out and pulverize, coarse particles of 100 ⁇ m or more by classification And calcined powder was obtained.
- Step 4 The calcined powder obtained in step 3 is put in a molybdenum container and heat-treated in a tungsten heater electric furnace at 1500 ° C. for 3 hours while flowing a 4% H 2 + 96% Ar mixed gas to obtain powdered phosphor powder. Obtained.
- the result of having measured X-ray diffraction about the obtained fluorescent substance powder is shown in FIG.
- the result of having measured the fluorescence characteristic is shown in FIG. In the X-ray diffraction result of FIG. 1, it was found that the obtained phosphor powder was almost a single phase of Sr 3 SiO 5 . Further, in the fluorescence characteristics shown in FIG.
- Example 1 A phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 2.0 mol / L. The results are shown in Table 1.
- Example 1 A phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was 5.5 mol / L. The results are shown in Table 1.
- Example 1 A phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was changed to 0.1 mol / L. The results are shown in Table 1.
- Example 2 A phosphor powder was produced in the same manner as in Example 1 except that the total aqueous solution concentration of strontium and europium was changed to 0.15 mol / L. The results are shown in Table 1.
- the concentration of the metal salt (Sr + Eu) aqueous solution is preferably 1 to 5.5 mol / L, and preferably 2 to 5.5 mol / L. L is good.
- a phosphor powder was produced in the same manner as in Example 1 except that the holding temperature at the time of gelation in Step 1 of Example 1 was 80 ° C.
- Table 2 shows the result of visual observation of the gelation state of the sample. In addition, the judgment criteria of gelation described in Table 2 is “ ⁇ ” when the fluidity is lost when the container is moved or inverted, and “x” when there is still fluidity. .
- Example 1 A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature at the time of gelation in Step 1 of Example 1 was set to 100 ° C. Table 2 shows the result of visual observation of the gelation state of the sample.
- Example 5 A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature at the time of gelation in Step 1 of Example 1 was 25 ° C. Table 2 shows the result of visual observation of the gelation state of the sample.
- Example 6 A phosphor powder was produced in the same manner as in Example 1 except that the holding temperature during gelation in Step 1 of Example 1 was 25 ° C. and the holding time was 96 hours. Table 2 shows the result of visual observation of the gelation state of the sample.
- Step 2 of Example 1 the transparent mixed solution was placed in a polytetrafluoroethylene container, further sealed in a stainless steel pressure-resistant container, and kept at 200 ° C. for 24 hours for gelation.
- the obtained sample consisted of gel and liquid and was separated into two layers. The weight of the liquid separated from the gel was 20% by mass.
- Table 3 shows the results of analyzing the components (Sr, Eu, Si) of the gel dry powders obtained in Example 1 and Comparative Example 7 and comparing the deviation from the charged composition.
- YAG: Ce which is a general yellow phosphor as a conventional example, was measured together.
- Example 1 From Table 4, it was found that in Example 1, the internal quantum efficiency was a very high value of 71.1%, which was superior to the conventional YAG: Ce phosphor.
- an Eu-activated alkaline earth metal silicate phosphor having a composition formula (Ba x , Sr 1-xy , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1) is prepared. It was produced under the following process conditions.
- Example 1 when strontium carbonate was weighed, a phosphor powder was prepared in the same manner as in Example 1 except that the molar ratio of Sr: Ba was 0.86: 0.13 between strontium carbonate and barium carbonate. . That is, the Eu-activated alkaline earth metal silicate phosphor represented by the composition formula (Ba 0.86 , Sr 0.13 , Eu 0.01 ) 3 SiO 5 .
- An Eu-activated alkaline earth metal silicate phosphor having a composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 was produced under the following process conditions.
- a citric acid (98.0%, manufactured by Wako Pure Chemical Industries, Ltd.) aqueous solution was weighed so that the total concentration of barium, strontium, and europium (hereinafter referred to as a metal salt (Sr + Eu) aqueous solution concentration) was 4 mol / L.
- BaCO 3 and SrCO 3 were added and stirred at 40 ° C. for 1 hour to obtain a transparent solution. Further, the weighed Eu (NO 3 ) 3 ⁇ 6H 2 O was dissolved in water to obtain an aqueous solution.
- 1,2-propanediol (0.4 mol) is added to tetramethoxysilane (0.1 mol), and a hot stirrer is used so that the liquid temperature becomes 54 ° C. And mixed for 24 hours with stirring.
- hydrochloric acid (0.0001 mol) was added, mixed with a water-soluble silicon compound at a liquid temperature of 54 ° C., combined with BaCO 3 solution and SrCO 3 solution, and stirred and mixed at room temperature for 30 minutes. Obtained.
- the mixed solution prepared as described above was put in a polypropylene container, sealed with a cap, and kept at 50 ° C. for 24 hours to obtain a transparent gel. This gel had elasticity, but was in a uniform state from the appearance without being separated into two layers.
- Step 2 The transparent gel obtained in step 1 was held at 120 ° C. for 6 hours with a dryer, the solvent in the gel was removed, and a dried gel was obtained. The dried gel was a transparent solid.
- Step 3 The dried gel obtained in step 2 is crushed in an agate mortar, heat-treated at 550 ° C. for 3 hours in an air atmosphere using an electric furnace, taken out and crushed, and again heat-treated at 800 ° C. for 3 hours. went. Furthermore, after taking out and crushing, it heat-processed in the atmospheric condition hold
- Step 4 The calcined powder obtained in step 3 is put in a molybdenum vessel and heat-treated using a tungsten heater electric furnace at 1200 ° C. for 3 hours while flowing a 4% H 2 + 96% Ar mixed gas to obtain a powdery phosphor. A powder was obtained.
- the method for producing Eu-activated strontium silicate phosphors having the composition formula (Sr 1-y , Eu y ) 3 SiO 5 (where 0 ⁇ Y ⁇ 0.1) of the present invention According to the above, a high-intensity yellow phosphor having a broad excitation absorption from ultraviolet to blue and having an emission band near 585 nm can be obtained.
- Eu-activated alkaline earth metal silicate fluorescence of the composition formula (Ba x , Sr 1-xy , Eu y ) 3 SiO 5 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1) According to the method for producing a body, a high-intensity orange phosphor having a broad excitation absorption from ultraviolet to blue and having an emission band near 600 nm can be obtained.
- Eu-activated alkaline earth metal silicate fluorescence of the composition formula (Ba x , Sr 1-xy , Eu y ) 2 SiO 4 (where 0 ⁇ X ⁇ 1, 0 ⁇ Y ⁇ 0.1) According to the method for producing a body, a high-luminance green phosphor having a broad excitation absorption from ultraviolet to blue and having an emission band near 529 nm can be obtained.
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Abstract
Description
この白色LEDに用いられる白色LED用蛍光体としては、従来、青色励起により黄色の蛍光を示すYAG:Ce3+や、緑から黄色の蛍光を示す(Ba,Sr,Ca)2SiO4:Eu2+、Sr3SiO5:Eu2+などが知られているが、より高輝度な蛍光体が望まれている。
その賦活剤としては、Ce3+、Eu2+、Tb3+を用いた蛍光体の製造には、H2ガスを数%含んだ不活性ガスによる還元性雰囲気下で熱処理するのが一般的である。この高温熱処理において、例えば、Sr3SiO5:Eu2+では、SrOとSiO2が反応して母体酸化物結晶を構成し、還元性雰囲気焼成により賦活剤のEuが3価から2価に還元され、母体結晶中のSr2+を置換する。これによりSr3SiO5:Eu2+蛍光体が合成できる。
特許文献2によれば、1種以上の金属元素、TEOSと溶媒からなる混合溶液を水熱処理すると、金属元素が均一に分散したゲル体の作製が可能であり、このゲルを乾燥、熱処理することで複合金属酸化物前駆体ができる。このゲルはTEOSが有するゲル化能を利用しているため、有機物が少ないという特徴がある。原子レベルで混合した液相を水熱ゲル化させることで均一な前駆体の作製が可能である。この前駆体は元素の拡散距離が短いため比較的低温の熱処理により、均一な化学組成の複合金属酸化物を形成することができる。ただし、TEOSのゲル化能を利用しているため金属成分中に占めるケイ素の組成比が小さい場合は、金属元素成分のすべてをゲル中に含有することはできないという問題を抱えている。
記
〔工程1〕
構成金属成分であるストロンチウム、バリウム、ユーロピウム、ケイ素の各元素原料毎の水溶液を作製し、作製した前記水溶液を混合した混合水溶液を、30~100℃の液温で保持することによって、全金属成分の全量が均一に分散した状態のゲルを形成する工程。
記
〔工程1〕
構成金属成分であるストロンチウム、バリウム、ユーロピウム、ケイ素の各元素原料毎の水溶液を作製し、作製したその水溶液を混合した混合水溶液を、30~100℃の液温で保持することにより、全金属成分の全量が均一に分散した状態のゲルを形成する工程。
〔工程2〕
工程1により形成された前記ゲルを乾燥して乾燥物を形成し、含まれる溶媒を除去する工程。
〔工程3〕
工程2における前記乾燥物を、大気雰囲気中で熱処理して有機物を除去し、仮焼粉を得る工程。
〔工程4〕
工程3により形成された前記仮焼粉を還元性雰囲気下で熱処理し、蛍光体粉末を得る工程。
さらに本発明の製造方法によれば、全金属成分を均一に含有するゲルを、オートクレーブのような圧力容器を必要とせずに合成するため、製造コストの低減が顕著であることから、その工業的意義は大きい。
まず、Eu賦活アルカリ土類金属シリケート蛍光体の製造工程について説明する。
〔工程1〕
この工程は、構成金属成分であるストロンチウム、バリウム、ユーロピウム、ケイ素の原料水溶液とし、それらを混合した後、30~100℃の温度で保持し、ストロンチウム、バリウム、ユーロピウム、ケイ素の全金属成分の全量が均一に分散したゲルを得る工程である。
この工程1では、まずストロンチウム、バリウム、ユーロピウム、ケイ素の全金属成分の原料水溶液を調製する。ストロンチウム原料としては、水に溶解し、水溶液のpHが7以下であるものであれば特に制限はなく、ストロンチウムの塩化物、酸化物、酢酸塩、硝酸塩、炭酸塩、硫酸塩、シュウ酸塩などを用いることができる。特に、加熱により陰イオン成分を容易に除去できることから、硝酸塩、酢酸塩、炭酸塩、シュウ酸塩などを用いることが望ましい。金属塩の溶解時にクエン酸、乳酸、リンゴ酸などのヒドロキシカルボン酸を加えても良い。この場合には、仕込みからの組成ズレを抑制できるため、硝酸塩などに比べて溶解度の小さい炭酸塩の水溶液とすることが好ましい。バリウム原料、ユーロピウム原料についても、ストロンチウム原料と同様である。なお、ストロンチウム、バリウムおよびユーロピウムの原料水溶液は、別々に作製して混合しても、混合水溶液を始めから一つの容器内で作製しても良い。
また、構成成分の金属元素に対して水が多すぎると、ゲルと液体が2層分離し、液相に金属イオンが溶出するためゲルが不均一な組成になる恐れがある。金属元素に対して水が少なすぎると、やはり均一な水溶液を作製できず、ゲル形成前に金属が析出して不均一なゲルとなる場合があり、本発明では、全金属成分元素を均一に分散させることが不可欠であるため、そのため水溶液としたときの金属元素濃度は1~5.5mol/Lとすることが重要である。望ましくは2~5.5mol/Lとするのが良い。
容器は特に限定することはないが、ガラス製、ポリプロピレン製、ポリテトラフルオロエチレン製など、加熱温度までの耐熱性のあるものを使用することができる。
工程2は、工程1で得られたゲルから溶媒を除去し、乾燥物を得る工程である。
この溶媒の除去は加熱による方法が簡便である。ゲルに含まれる溶媒成分は、水、エタノール、プロピレングリコールであるため、100~120℃が望ましい。加熱時間は試料量にも依存するが、1から6時間程度が好ましい。
工程3は、工程2で得られた固体状の乾燥物を大気中で熱処理を行い、有機物を熱分解除去し、さらにEu賦活アルカリ土類金属シリケート蛍光体の前駆体である仮焼粉を得る工程である。
この大気中での熱処理は、原料に含まれる有機物の分解と、分解により生成する炭素の除去、さらにEu賦活アルカリ土類金属シリケート蛍光体の酸化物母結晶の結晶成長を行うことを目的とするものである。
この大気中の熱処理の条件は、400~1600℃の温度で行われる。また、この熱処理は1回の熱処理で行っても良く、複数回に分けて行っても良いが、複数回にわたって熱処理を行う場合には、熱処理のたびに乳鉢などで解砕を行うことが望ましい。
焼成温度は酸化物母結晶がSr3SiO5の場合は1300℃より低い温度では結晶相が得にくく、1600℃を超える温度ではアルミナルツボと反応するため1300℃~1600℃の温度範囲が好ましい。特に好ましくは1450℃から1550℃である。この熱処理温度が低すぎると異相であるSr2SiO4相が不純物として生成し、最終的に得られる蛍光体の発光強度を低下させることになるため好ましくない。この熱処理温度が高すぎると、Sr3SiO5結晶が焼結したり、溶融したりして、粉砕無しで粉末状蛍光体を得ることが困難になる。蛍光体を粉砕することは、結晶にダメージを与えるので、高輝度蛍光体を得るためには望ましくない。
この熱処理温度が低すぎると、同様に異相であるBaCO3相やSrCO3相が未反応不純物として残存し、最終的に得られる蛍光体の発光強度を低下させることになるため好ましくない。反対に、この熱処理温度が高すぎると、焼成物が焼結したり、溶融したりして、粉砕により粉末状蛍光体を得ることが必要となる。また、蛍光体を粉砕することは、結晶にダメージを与えるので、高輝度蛍光体を得るためには望ましくない。
なお、以上の熱処理は複数回の熱処理を行っても良く、最適な条件で1回の熱処理で行っても良く、さらに、連続して個々の熱処理に適合した熱処理条件に変えながら、1回の熱処理サイクルで行っても良い。
工程4は、工程3で得られた仮焼粉を、還元性雰囲気下で熱処理し、Eu2+を母体結晶中の2価ストロンチウムイオンや2価バリウムイオンと置換して蛍光体を得る工程である。ここで使用する仮焼粉は、工程3で完全に炭酸塩を分解した酸化物でもよいし、一部炭酸塩を含んだ状態の仮焼粉でもよい。
また、酸化物母結晶が(Bax,Sr1-x)3SiO5、(Bax,Sr1-x)2SiO4の場合は、工程3と同様に1000~1400℃、好ましくは1000~1350℃とする。
還元性雰囲気としては、N2やArなどの不活性ガスに1~10vol%のH2を混合したガスを使用することができる。
なお、本発明のEu賦活アルカリ土類金属シリケート蛍光体の製造方法は、酸化物母結晶が組成式Sr2SiO4や、他のアルカリ土類金属元素を組成に含むアルカリ土類シリケート蛍光体を製造する場合にも、適用できることが十分に考えられ、期待できる。
Eu賦活アルカリ土類金属シリケート蛍光体として、組成式(Sr1-y,Euy)3SiO5(但し、0<Y<0.1)の黄色蛍光体を用いて、その製造方法を示す。
水溶性ケイ素化合物は、特許文献3の段落[0046]に記載の製造例1(水溶性ケイ素化合物A)を参照した。
組成ズレの評価は、各元素のICP発光分析による定量分析によって行った。
発光特性の評価は、蛍光分光光度計FP-6500(日本分光株式会社製)を用いて、励起、発光スペクトルの測定を行った。なお、発光スペクトルは励起光波長を455nmとして測定し、励起スペクトルは発光スペクトルのピーク波長において測定したものである。
〔工程1〕
金属元素化合物としてSrCO3(3N、関東化学株式会社製)、Eu(NO3)3・6H2O(3N、三津和化学薬品株式会社製)を式(Sr1-yEuy)3SiO5においてy=0.01となるように秤量した。クエン酸(98.0%、和光純薬工業株式会社製)水溶液に、ストロンチウムとユーロピウムの合計濃度(以下、金属塩(Sr+Eu)水溶液濃度と称す)が4.0mol/Lとなるように秤量したSrCO3を入れ、40℃で1時間攪拌することで透明溶液を得た。また、秤量したEu(NO3)3・6H2Oを水に溶解し水溶液を得た。
上記のとおり作製した混合溶液をポリプロピレン製容器に入れキャップをして密封し、50℃で24時間保持し、透明なゲルを得た。このゲルは弾力性を持つが、2層分離せずに、外観から一様な状態であった。
工程1で得た透明ゲルを乾燥機に120℃で6時間保持し、ゲル中の溶媒を除去し、乾燥ゲルを得た。乾燥ゲルは透明な固体状であった。
工程2で得た乾燥ゲルをメノウ乳鉢で解砕し、電気炉で大気雰囲気中で550℃で3時間の熱処理を行い、取り出して解砕した後、再度800℃で3時間の熱処理を行った。さらに取り出して解砕した後、1200℃で3時間保持し、続けて1500℃に昇温し、3時間保持し大気雰囲気中で熱処理を行い、取り出して解砕し、分級により100μm以上の粗大粒子を除去し、仮焼粉を得た。
工程3で得た仮焼粉を、モリブデン製容器に入れ、タングステンヒーター電気炉で1500℃で3時間、4%H2+96%Ar混合ガスをフローさせながら熱処理し、粉状の蛍光体粉末を得た。
得られた蛍光体粉末について、X線回折を測定した結果を図1に示す。また、蛍光特性を測定した結果を図2に示す。
図1のX線回折結果において、得られた蛍光体粉末はSr3SiO5のほぼ単相であることがわかった。また、図2の蛍光特性において、300~500nmにかけてブロードな励起吸収が見られ、585nm付近にピークを示し、黄色発光を確認した。比較のために示したYAG:Ceよりも発光スペクトルはシャープで、発光ピーク強度、発光ピーク面積、共に大きく、高輝度の組成式(Sr1-y,Euy)3SiO5(但し、0<Y<0.1)のEu賦活ストロンチウムシリケート蛍光体が得られた。
実施例1において、ストロンチウムとユーロピウムの合計の水溶液濃度を0.1mol/Lとした以外は実施例1と同様にして蛍光体粉末を作製した。その結果を表1に示す。
実施例1において、ストロンチウムとユーロピウムの合計の水溶液濃度を0.15mol/Lとした以外は実施例1と同様にして蛍光体粉末を作製した。その結果を表1に示す。
実施例1において、ストロンチウムとユーロピウムの合計の水溶液濃度を0.2mol/Lとした以外は実施例1と同様にして蛍光体粉末を作製した。その結果を表1に示す。
実施例1において、ストロンチウムとユーロピウムの合計の水溶液濃度を6.0mol/Lとした以外は実施例1と同様にして蛍光体粉末を作製した。その結果を表1に示す。
なお、表2に記載したゲル化の判断基準は、容器を動かしたり、反転させたりしたときに流動性が無くなっていることを「○」とし、まだ流動性がある場合は「×」とした。
実施例1の工程1におけるゲル化する際の保持温度を25℃とした以外は実施例1と同様にして、蛍光体粉末を作製した。試料のゲル化状態を目視で観察した結果を表2に示す。
実施例1の工程1におけるゲル化する際の保持温度を25℃、保持時間を96時間とした以外は実施例1と同様にして、蛍光体粉末を作製した。試料のゲル化状態を目視で観察した結果を表2に示す。
実施例1の工程2において、透明混合溶液をポリテトラフルオロエチレン製の容器に入れ、さらにステンレス製の耐圧容器に入れて密封し、200℃で24時間保持してゲル化を行った。得られた試料はゲルと液体とからなり、二層分離していた。
このゲルから分離した液体の重量は、全体の20質量%であった。実施例1及び比較例7で得られたゲル乾燥粉について、成分(Sr,Eu,Si)の分析を行い、仕込み組成とのズレを比較した結果を表3に示す。
以上のように、ゲル化時の保持温度は本発明においては重要であり、均一な組成の形成には重要な要因である。
実施例1により得られた蛍光体粒子の蛍光特性(発光スペクトルは励起光波長:Ex=455nmにて測定)における量子効率を、積分球を用いて測定して求めた結果を表4に示す。比較のために、従来例として一般的な黄色蛍光体であるとして一般的なYAG:Ceをあわせて測定した。
実施例1において、炭酸ストロンチウムを秤量する際に、炭酸ストロンチウムと炭酸バリウムとをSr:Baのモル比0.86:0.13とした以外は実施例1と同様にして蛍光体粉末を作製した。すなわち組成式(Ba0.86,Sr0.13,Eu0.01)3SiO5で表されるEu賦活アルカリ土類金属シリケート蛍光体である。
したがって、高輝度の組成式(Bax,Sr1-x-y,Euy)3SiO5のEu賦活アルカリ土類金属シリケート蛍光体が得られた。
〔工程1〕
金属元素化合物としてBaCO3(3N、関東化学株式会社製)、SrCO3(3N、関東化学株式会社製)、Eu2O3(3N、フルウチ化学製)を式(Bax,Sr1-x-y,Euy)2SiO4においてx=0.69、y=0.08となるように秤量した。クエン酸(98.0%、和光純薬工業株式会社製)水溶液に、バリウム、ストロンチウム、ユーロピウムの合計濃度(以下、金属塩(Sr+Eu)水溶液濃度と称す)が4mol/Lとなるように秤量したBaCO3、SrCO3を入れ、40℃で1時間攪拌することで透明溶液を得た。また、秤量したEu(NO3)3・6H2Oを水に溶解し水溶液を得た。
上記のとおり作製した混合溶液をポリプロピレン製容器に入れキャップをして密封し、50℃で24時間保持し、透明なゲルを得た。このゲルは弾力性を持つが、2層分離せずに、外観から一様な状態であった。
工程1で得た透明ゲルを乾燥機で120℃に6時間保持し、ゲル中の溶媒を除去し、乾燥ゲルを得た。乾燥ゲルは透明な固体状であった。
工程2で得た乾燥ゲルをメノウ乳鉢で解砕し、電気炉を用い大気雰囲気中で、550℃で3時間の熱処理を行い、取り出して解砕した後、再度800℃で3時間の熱処理を行った。さらに取り出して解砕した後、1200℃で6時間保持する大気雰囲気中での熱処理を行い、取り出して解砕し、仮焼粉を得た。
工程3で得た仮焼粉を、モリブデン製容器に入れ、タングステンヒーター電気炉を用い、1200℃で3時間、4%H2+96%Ar混合ガスをフローさせながら熱処理し、粉状の蛍光体粉末を得た。
図3の蛍光特性において、370nm付近にピークを持つ励起吸収が見られ、発光は529nm付近にピークを示し、緑色発光を確認した。高輝度の組成式(Bax,Sr1-x-y,Euy)2SiO4のEu賦活アルカリ土類金属シリケート蛍光体が得られた。
工程3の大気雰囲気中での熱処理温度を1300℃とし、工程4の還元性雰囲気中での熱処理温度を1300℃とした以外は実施例7と同様に組成式(Bax,Sr1-x-y,Euy)2SiO4のEu賦活アルカリ土類金属シリケート蛍光体を合成した。工程4の後、試料は硬く焼結し、粉末状試料を得るために粉砕を必要とした。粉砕後の試料の蛍光特性を評価したところ、図3に示すように実施例7と同様に370nm付近にピークを持つ励起吸収が見られ、発光は529nm付近にピークを示したが、実施例7の試料より発光強度が劣ることがわかった。
工程3の大気雰囲気中での熱処理温度を1000℃とし、工程4の還元性雰囲気中での熱処理温度を1000℃とした以外は実施例7と同様に組成式(Bax,Sr1-x-y,Euy)2SiO4のEu賦活アルカリ土類金属シリケート蛍光体を合成した。
試料の蛍光特性を評価したところ、図3に示すように実施例7と同様に370nm付近にピークを持つ励起吸収が見られ、発光は529nm付近にピークを示したが、実施例7の試料より大きく発光強度が劣ることがわかった。
Claims (5)
- 組成式(Sr1-y,Euy)3SiO5(但し、0<Y<0.1)、組成式(Bax,Sr1-x-y,Euy)3SiO5(但し、0<X<1、0<Y<0.1)、組成式(Bax,Sr1-x-y,Euy)2SiO4(但し、0<X<1、0<Y<0.1)の群から選ばれるEu賦活アルカリ土類金属シリケート蛍光体の製造方法において
下記工程1を含むことを特徴とするEu賦活アルカリ土類金属シリケート蛍光体の製造方法。
記
〔工程1〕
構成金属成分であるストロンチウム、バリウム、ユーロピウム、ケイ素の各元素原料毎の水溶液を作製し、作製した前記水溶液を混合した混合水溶液を、30~100℃の液温で保持することにより、全金属成分の全量が均一に分散した状態のゲルを形成する工程。 - 組成式(Sr1-y,Euy)3SiO5(但し、0<Y<0.1)、組成式(Sr1-y,Euy)3SiO5(但し、0<Y<0.1)(Bax,Sr1-x-y,Euy)3SiO5(但し、0<X<1、0<Y<0.1)、組成式(Bax,Sr1-x-y,Euy)2SiO4(但し、0<X<1、0<Y<0.1)の群から選ばれるEu賦活アルカリ土類金属シリケート蛍光体の製造方法において、
下記工程1から工程4を含むことを特徴とするEu賦活アルカリ土類金属シリケート蛍光体の製造方法。
記
〔工程1〕
構成金属成分であるストロンチウム、バリウム、ユーロピウム、ケイ素の各元素原料毎の水溶液を作製し、作製した前記水溶液を混合した混合水溶液を、30~100℃の液温で保持することにより、全金属成分の全量が均一に分散した状態のゲルを形成する工程。
〔工程2〕
工程1により形成された前記ゲルを乾燥して乾燥物を形成し、含まれている溶媒を除去する工程。
〔工程3〕
工程2における前記乾燥物を、大気雰囲気中で熱処理して有機物を除去し、仮焼粉を得る工程。
〔工程4〕
工程3により形成された前記仮焼粉を還元性雰囲気下で熱処理し、蛍光体粉末を得る工程。 - 前記工程1における前記混合水溶液中での構成金属成分であるストロンチウム、バリウムおよびユーロピウムの濃度が、1~5.5mol/Lとすることを特徴とする請求項1または2に記載のEu賦活アルカリ土類金属シリケート蛍光体の製造方法。
- 前記工程1におけるケイ素原料の水溶液が、テトラメトキシシランに、1,2-プロパンジオールを添加して加熱、撹拌、混合した後、塩酸を添加した水溶性ケイ素水溶液であることを特徴とする請求項1または2に記載のEu賦活アルカリ土類金属シリケート蛍光体の製造方法。
- 前記工程3の後に、前記工程3で形成された仮焼粉から分級により100μm以上の粗大粒子を除去する工程を含むことを特徴とする請求項2に記載のEu賦活アルカリ土類金属シリケート蛍光体の製造方法。
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JP2012136594A (ja) * | 2010-12-24 | 2012-07-19 | Sumitomo Metal Mining Co Ltd | アルカリ土類金属シリケート蛍光体の製造方法 |
JP2012144689A (ja) * | 2010-12-24 | 2012-08-02 | Sumitomo Metal Mining Co Ltd | シリケート蛍光体およびその製造方法 |
JP2013129765A (ja) * | 2011-12-22 | 2013-07-04 | Sumitomo Metal Mining Co Ltd | アルカリ土類金属シリケート蛍光体の製造方法およびアルカリ土類金属シリケート蛍光体 |
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