WO2010119799A1 - 赤色蛍光体、その製造方法及び発光素子 - Google Patents
赤色蛍光体、その製造方法及び発光素子 Download PDFInfo
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- WO2010119799A1 WO2010119799A1 PCT/JP2010/056308 JP2010056308W WO2010119799A1 WO 2010119799 A1 WO2010119799 A1 WO 2010119799A1 JP 2010056308 W JP2010056308 W JP 2010056308W WO 2010119799 A1 WO2010119799 A1 WO 2010119799A1
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/67—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing refractory metals
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/67—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing refractory metals
- C09K11/671—Chalcogenides
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
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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
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/57—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing manganese or rhenium
Definitions
- the present invention relates to red phosphor particles having titanate as a base material and a method for producing the same.
- the present invention also relates to a light emitting device using the red phosphor particles.
- Light emitting diodes have the advantages of being light, do not use mercury, and have a long life.
- a white light emitting diode in which Y 3 Al 5 O 12 : Ce is coated on a blue light emitting element is known.
- the light emitting diode is not white but becomes white mixed with green and blue. Therefore, it has been proposed to adjust the color tone by mixing Y 3 Al 5 O 12 : Ce with a red phosphor that absorbs blue light and emits red fluorescence.
- red phosphors that absorb blue light and emit red fluorescence, but there are few reports on inorganic materials.
- inorganic materials such as oxide phosphors, oxysulfide phosphors, sulfide phosphors, and nitride phosphors have been proposed as general red phosphors, and phosphors based on titanates are also known. Proposed.
- red emission fluorescence obtained by activating trivalent Eu to a titanate represented by the general formula: M 2 TiO 4 (M represents an alkaline earth metal element). The body has been proposed.
- Patent Document 2 the general formula Me I x Me II y Ti 1 -a O 4 X m: in Mn z (wherein, Me I is a divalent or trivalent cation, Me II is a monovalent cation , X is Cl or F that balances the electric charge, and 0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 4, 0 ⁇ m ⁇ 4, 0 ⁇ a ⁇ 1, 0 ⁇ z ⁇ 0.5) Phosphors and the like have been proposed.
- the phosphors based on titanates in these conventional technologies are prepared by mixing an alkaline earth metal source, titanic acid source and an activating component in a dry or wet manner, and obtaining a uniform mixture of these raw materials, followed by firing. As a result, the obtained red light emitter had a problem in light emission intensity and the quantum yield was low.
- the present invention provides red phosphor particles whose performance is further improved over conventional phosphors and a method for producing the same.
- the present invention provides the following general formula (1) M 2 TiO 4 (1) (Wherein M represents one or two or more alkaline earth metal elements), Mn is activated to the titanate represented, and a plurality of primary particles are combined to form a spherical shape,
- M represents one or two or more alkaline earth metal elements
- Mn is activated to the titanate represented, and a plurality of primary particles are combined to form a spherical shape
- the present invention provides a red phosphor particle characterized by a surface state in which grain boundaries between primary particles are not observed on the surface when observed with an electron microscope at a magnification of 3000 times.
- the present invention prepares a mixed solution in which an alkaline earth metal source, a manganese source, and a titanium source are mixed with a dispersion medium, and this mixed solution is wet mixed by a media mill. Then, the mixed liquid is subjected to a spray drying method to form a dry powder, and the dried powder is fired to obtain a fired body, and then the fired body is annealed. A manufacturing method is provided.
- red phosphor particles having a high emission intensity of red light are provided. Further, according to the production method of the present invention, the red phosphor particles can be obtained by an industrially advantageous method.
- FIGS. 1A and 1B are SEM images of the red phosphor particles obtained in Example 1.
- FIG. 1A is a magnification of 10,000 times
- FIG. 1B is a magnification of 3000 times.
- FIGS. 2A and 2B are SEM images of the red phosphor particles obtained in Comparative Example 1.
- FIG. 2A is a magnification of 10,000 times
- FIG. 2B is a magnification of 3000 times.
- FIG. 3 is an SEM image of the red phosphor particles obtained in Comparative Example 2, and the magnification is 3000 times.
- the red phosphor particles of the present invention are activated by adding Mn to a base crystal containing titanic acid represented by the general formula (1) to obtain M 2 TiO 4 : Mn.
- M in the formula is one or more alkaline earth metal elements. Examples thereof include calcium, magnesium, strontium and barium. Of these alkaline earth metal elements, it is particularly preferable to use magnesium because the emission intensity of the red phosphor becomes extremely high.
- Mn used for activation is divalent to tetravalent, and it is particularly preferable to use tetravalent Mn from the viewpoint that the quantum yield of the red phosphor is high and the emission intensity is high.
- the amount of Mn used for activation is preferably 0.01 to 3 mol%, more preferably 0.1 to 1.5 mol% as Mn atoms, based on the total number of moles of Ti and Mn.
- the red phosphor is preferable in terms of higher quantum yield and higher emission intensity.
- the red phosphor particles of the present invention have one of the characteristics of the particle shape. Specifically, the red phosphor particles are (a) spherical and (b) a surface state in which no grain boundary between primary particles is observed on the surface when observed with an electron microscope at a magnification of 3000 times. This is one of the characteristics. Only when these shapes (a) and (b) are realized in one particle, it is possible to obtain red phosphor particles having a higher quantum yield and a higher emission intensity.
- the red phosphor particles do not necessarily have to be true spheres as long as the shape of the particles can be regarded as spherical.
- the degree of sphericity can be expressed by sphericity, but the red phosphor particles only need to have a sphericity of about 1.0 to 1.8, particularly about 1.0 to 1.7. .
- Spherical red phosphor particles have higher quantum yields and higher emission intensity than other shaped particles.
- the sphericity is defined by the area of the perfect circle formed by the maximum diameter of the projected figure when the particle is projected two-dimensionally / the actual area of the projected figure. Therefore, the closer the sphericity value is to 1, the closer the particle is to a true sphere.
- the precursor particles of the red phosphor particles may be produced using a spray drying method, and the precursor particles may be fired.
- the red phosphor particles are a combination of fine primary particles.
- the boundary lines between the primary particles have almost disappeared, and the surface is smooth in appearance. Whether the surface state of the red phosphor particles is smooth or not is determined by observing the red phosphor particles at a magnification of 3000 times with a scanning electron microscope (SEM) on the surface of the particles.
- Judgment is made based on whether or not (grain boundaries) are observed.
- boundary line (grain boundary) between the primary particles is not observed in the 3000 times SEM image of the red phosphor particles, it is determined that the particles are in a smooth surface state. Note that the boundary line (grain boundary) between the primary particles is not observed not only when the boundary line is not observed at all, but also the linear part is observed in part, but the part is the original primary. This includes a case where a plurality of particles are merged and the shape of the original primary particles is not retained.
- the red phosphor particles of the present invention have a high internal quantum efficiency due to the smoothness to the extent that the boundary lines (grain boundaries) of the primary particles are not observed on the surface of the red phosphor particles. Is expensive. On the other hand, in the red phosphor particles in which the boundary line (grain boundary) between the primary particles is clearly present and the smoothness of the surface is impaired, the light generated in the particles is difficult to be emitted to the outside. As a result, the emission intensity cannot be increased.
- the degree of smoothness of the surface of the red phosphor particles can be expressed by, for example, the degree of unevenness.
- the degree of unevenness of the particles of the present invention is about 1.0 to 1.25, particularly 1.0 to 1.2. What is necessary is just to have the smoothness of a grade.
- the degree of unevenness is defined as the area of a perfect circle calculated from the perimeter of the projected figure when the particles are projected two-dimensionally / the actual area of the projected figure. Therefore, the closer the roughness value is to 1, the smoother the surface of the particles.
- the firing conditions for firing the precursor particles of the red phosphor particles may be appropriately controlled.
- the sphericity and unevenness can be measured using, for example, an image analyzer.
- An example of such an apparatus is LUZEX AP manufactured by Nicole. The measurement is performed on 300 particles arbitrarily extracted. The magnification of the particles is 400 to 300,000 times depending on the size.
- the red phosphor particles preferably have an average particle size of 1 to 30 ⁇ m, particularly 10 to 25 ⁇ m. By having an average particle diameter in this range, excitation light can be absorbed more efficiently.
- the average particle diameter is measured by a laser diffraction / scattering particle size distribution analyzer (LA-920) manufactured by Horiba.
- the red phosphor particles preferably have a BET specific surface area of 0.05 to 1.0 m 2 / g, particularly 0.1 to 0.5 m 2 / g.
- a BET specific surface area of 0.05 to 1.0 m 2 / g, particularly 0.1 to 0.5 m 2 / g.
- the secondary particle diameter of the raw material may be controlled by a spray dryer.
- the BET specific surface area can be measured using, for example, a specific surface area measuring device (Flowsorb II 2300) manufactured by Shimadzu Corporation.
- the red phosphor particles are substantially free of Si, specifically, the Si content is 24000 ppm or less, particularly 12000 ppm or less, particularly 500 ppm or less.
- Si is an impurity in the red phosphor particles, and Si is a substance that causes a significant decrease in emission intensity as compared with other impurities. Therefore, the lower the Si content, the better.
- red phosphors including red phosphors obtained by activating Mn to the titanate represented by the general formula (1)
- red phosphors are generally used as a metal source as a raw material. It is derived from various impurities.
- impurities there has been no report on the influence of impurities on the performance of red phosphors.
- the present inventors examined the performance of the red phosphor obtained by activating Mn in the titanate represented by the general formula (1) by paying attention to the impurity, and the impurity affects the emission intensity. I found out. Further investigation revealed that Si among the impurities has a great influence on the emission intensity. When the amount of Si is set to the above value or less, a clear improvement effect is recognized in the emission intensity.
- the Si content in the red phosphor particles can be quantified as follows. Using a fluorescent X-ray analyzer (ZSX100e) manufactured by Rigaku Corporation, it is calculated from the peak intensity value of K ⁇ rays in the range of 108 to 110 degrees. Moreover, although not clear, in the red phosphor particles, Si is considered to exist in a state of being dissolved in the phosphor crystal.
- ZSX100e fluorescent X-ray analyzer
- this production method a mixed liquid in which an alkaline earth metal source, a manganese source and a titanium source are mixed with a dispersion medium is prepared, the obtained mixed liquid is wet-mixed by a media mill, and the mixed liquid is subjected to a spray drying method. Then, after the dry powder is fired to obtain a fired body, the fired body is annealed. That is, this manufacturing method roughly includes (a) a mixed solution preparation step, (b) a spray drying step, (c) a firing step, and (d) an annealing treatment step.
- an alkaline earth metal source, a manganese source, and a titanium source are uniformly mixed with a dispersion medium to prepare a mixed solution.
- the alkaline earth metal source that can be used include oxides, hydroxides, carbonates, nitrates, sulfates, and organic acid salts of alkaline earth metals. These compounds can use 1 type (s) or 2 or more types. Among these, hydroxides are preferable in that no impurities remain after firing and high reactivity between raw materials.
- the alkaline earth metal source may be water-soluble or water-insoluble. When the alkaline earth metal source is water-insoluble, the average particle size is preferably 5 ⁇ m or less, particularly 0.2 to 2 ⁇ m, from the viewpoint of easy uniform mixing.
- manganese source for example, manganese oxide, hydroxide, carbonate, nitrate, sulfate, organic acid salt and the like can be used. These compounds can use 1 type (s) or 2 or more types. Among these, manganese carbonate is preferable in that impurities do not remain after firing and it is easily dissolved in the base crystal.
- the manganese source may be water-soluble or water-insoluble. When the manganese source is water-insoluble, its average particle size is preferably 10 ⁇ m or less, particularly 1 to 9 ⁇ m, from the viewpoint of easy uniform mixing.
- titanium oxide, hydroxide, halide, alkoxide compound, or the like can be used. These compounds can use 1 type (s) or 2 or more types. Among these, titanium oxide (TiO 2 ) is preferable in that no impurities remain after firing and it is relatively easily available.
- the titanium oxide (TiO 2 ) to be used may be obtained by a sulfuric acid method or a chlorine method, and may be used without particular limitation even if it is an anatase type or rutin type.
- the titanium source may be water-soluble or water-insoluble. When the titanium source is water-insoluble, the average particle size is preferably 5 ⁇ m or less, particularly 0.2 to 2 ⁇ m, from the viewpoint of easy uniform mixing.
- the red phosphor particles preferably have a Si content of 24000 ppm or less. Therefore, in the mixed solution preparation step, as the metal sources, those having high purity such that the amount of Si contained in them is 24000 ppm or less in the red phosphor obtained is used. It is preferable.
- the inventors of the present invention have found that mixing of Si into the red phosphor mainly originates from a raw material titanium source (for example, titanium oxide). Therefore, it is preferable to use a titanium source having a high purity with an Si content of 9000 ppm or less, particularly 6000 ppm or less.
- the alkaline earth metal source and the manganese source it is preferable to use a high-purity material having a low Si content, similarly to the titanium source.
- the Si content of the alkaline earth metal source and the manganese source is generally lower than that of the titanium source, there is usually no problem in this production method. It is preferable to use an alkaline earth metal source having a purity of Si content of ppm or less and a manganese source having a purity of Si content of 100 ppm or less.
- the mixing ratio of the alkaline earth metal source and the titanium source is such that the molar ratio (M / Ti) of the alkaline earth metal atom (M) in the alkaline earth metal source to the titanium atom (Ti) in the titanium source is 1.6. From 2.5 to 2.5, particularly from 1.8 to 2.2, it is preferable from the viewpoint that a single crystal is easily obtained and the internal quantum efficiency is excellent.
- the mixing ratio of the manganese source is 0.01 to 3 mol%, particularly 0.1 to 1.5 mol% as Mn atoms with respect to the obtained titanate, which absorbs excitation light well and absorbs light. It is preferable from the viewpoint of excellent conversion efficiency.
- Alkaline earth metal source, manganese source and titanium source are mixed with a dispersion medium to form a mixed solution.
- a dispersion medium it is preferable to use water or an aqueous liquid in which a water-soluble organic solvent is mixed with water.
- the solid concentration in the mixed solution is preferably 5 to 40% by weight, particularly 10 to 30% by weight, from the viewpoint of efficient mixing using a media mill.
- this manufacturing method processing using a media mill, which is a device that can simultaneously perform pulverization and mixing, is performed.
- a uniform mixed solution can be obtained more easily, and the grain boundary between primary particles can be easily lost in the firing step described later.
- a bead mill As the media mill, a bead mill, a ball mill, a paint shaker, an attritor, a sand mill, or the like can be used. It is particularly preferable to use a bead mill. In that case, the operating conditions and the types and sizes of the beads may be appropriately selected according to the size and throughput of the apparatus, the types of alkaline earth metal source, manganese source, and titanium source.
- a dispersant may be added to the mixed solution. What is necessary is just to select a suitable dispersing agent to use according to the kind of dispersion medium.
- the dispersion medium is water, for example, various surfactants, polycarboxylic acid ammonium salts, and the like can be used as the dispersant.
- the concentration of the dispersant in the mixed solution is preferably 0.01 to 10% by weight, particularly 0.1 to 5% by weight, from the viewpoint of a sufficient dispersion effect.
- the mixing process using the media mill can be performed until the average particle size of the solid content is 0.5 ⁇ m or less, particularly 0.1 to 0.5 ⁇ m. From the viewpoint of being able to disappear.
- This average particle diameter can be measured by a light scattering particle size distribution measuring apparatus.
- the mixed liquid thus obtained is subjected to the spray drying step (b) to obtain a dry powder.
- methods other than the spray drying method are known as the drying method of the mixed liquid, this drying method is adopted based on the knowledge that it is advantageous to select the spray drying method in this production method. .
- a spray dry method when a spray dry method is used, a dry powder having a spherical shape or a shape close thereto can be obtained, so that spherical red phosphor particles can be easily obtained.
- a dry powder in which the solid content particles are densely packed can be obtained, so that the grain boundaries between the primary particles are easily lost in the firing step (c). be able to.
- a dry powder is obtained by atomizing the liquid mixture by a predetermined means and drying fine droplets generated thereby.
- a method using a rotating disk and a method using a pressure nozzle for atomization of the mixed liquid There are, for example, a method using a rotating disk and a method using a pressure nozzle for atomization of the mixed liquid. Any method can be used in this step.
- the relationship between the size of the droplets of the atomized liquid mixture and the size of the raw material particles contained therein affects stable drying and the properties of the resulting dry powder. . Specifically, if the size of the solid material particles is too small with respect to the size of the droplets, the droplets become unstable, making it difficult to dry successfully. From this point of view, the size of the atomized droplets should be 2 to 500 ⁇ m, particularly 10 to 300 ⁇ m, provided that the size of the solid material particles in the mixed solution is in the above-mentioned range. preferable. It is desirable to determine the supply amount of the mixed liquid to the spray dryer in consideration of this viewpoint.
- the spray drying method is preferably performed so that the average particle size of the dry powder is 1 to 50 ⁇ m, particularly 5 to 35 ⁇ m, from the viewpoint of controlling the particle size of the target red phosphor particles.
- This average particle diameter is measured using, for example, a light scattering particle size distribution measuring apparatus.
- the spherical dried powder thus obtained is subjected to the firing step (c) to obtain a fired body.
- the firing conditions affect the smoothness of the surface of the obtained red phosphor particles. Specifically, by setting the firing temperature higher, the coalescence of the primary particles is facilitated, and the surface-state red phosphor particles in which the grain boundaries between the primary particles are not observed can be easily manufactured. .
- the firing temperature also depends on the size of the raw material particles constituting the dry powder, and in order to eliminate the grain boundaries between the primary particles, the larger the raw material particles, the higher the firing temperature is set. There is a need to.
- the size of the solid content particles constituting the dry powder that is, the size of the solid content particles after being processed by the media mill
- this range is used.
- a firing temperature such that the grain boundary between the primary particles disappears in a temperature range of 1150 to 1600 ° C., particularly 1200 to 1350 ° C., may be appropriately selected.
- the firing temperature affects the surface state of the red phosphor particles
- the firing time is not critical in this production method. In general, satisfactory red phosphor particles can be obtained by firing for 1 hour or longer, particularly 3 to 20 hours.
- the firing atmosphere is not critical in the present production method, and may be, for example, an oxidizing gas atmosphere such as the air or an inert gas atmosphere.
- the fired body obtained in this way may be subjected to a plurality of firing steps as necessary. Further, prior to performing the annealing treatment step, the particle size characteristics may be adjusted by performing classification or the like in advance if necessary.
- the fired body obtained by the firing step (c) is subjected to the annealing treatment step (d) to obtain target red phosphor particles.
- the emission intensity can be significantly increased.
- the structure of the base crystal changes from cubic to tetragonal so that the light energy absorbed by the light-emitting ions can be efficiently converted into light emission. It is thought to be.
- the fired body is heated for a predetermined time at a temperature lower than that in the firing step.
- the annealing temperature is preferably 500 to 800 ° C., particularly 550 to 700 ° C., provided that the annealing temperature is lower than the firing temperature.
- the annealing time is preferably 1 hour or more, particularly 1 to 24 hours.
- the atmosphere for the annealing treatment is not particularly limited, and may be any of an oxidizing atmosphere such as air and an inert gas atmosphere.
- the annealing treatment can be performed as many times as necessary. Further, the red phosphor particles after the annealing treatment may be classified as necessary.
- the annealing treatment may be performed continuously from the firing step, or may be performed after the fired body is once cooled to room temperature after the firing step.
- the red phosphor particles thus obtained can be used for various light-emitting elements such as display devices such as electrolytic emission displays, plasma displays, and electroluminescence. Moreover, since it has an excitation spectrum close to around 460 nm, it can be applied to the use of a phosphor for exciting a blue LED. It is particularly suitable for use in electroluminescent display devices. Also, by a method using in combination with a blue excited green phosphor, a method using in combination with a blue LDE element and a blue excited green phosphor, or a method using in combination with a blue LDE element and a blue excited yellow light emitting phosphor, etc. It can also be applied to white LEDs.
- Example 1 Magnesium hydroxide (average particle size: 0.57 ⁇ m), titanium oxide (average particle size: 0.64 ⁇ m, Si content: 43 ppm) and manganese carbonate (average particle size: 5.2 ⁇ m), magnesium: titanium: manganese molar ratio is 2 : 0.996: 0.004 was weighed and charged into the tank. Water and a dispersant (manufactured by Kao Corporation, Poise 2100) were added to the tank to prepare a mixed solution having a solid content concentration of 15%. The concentration of the dispersant was 2%.
- the mixture was supplied to a media stirring type bead mill charged with zirconia balls having a diameter of 0.5 mm, and mixed and ground by a wet method for 60 minutes.
- the average particle size of the slurry after mixing and pulverization was measured by a light scattering method, it was 0.15 ⁇ m.
- the mixed solution was supplied to a spray dryer set at 200 ° C. at a supply rate of 3 L / h to obtain a dry powder.
- the average particle size of the dry powder was 20 ⁇ m.
- the dried powder was charged into an electric furnace and fired in the air at 1250 ° C. for 5 hours.
- the fired product taken out was crushed and then charged again in an electric furnace and annealed at 600 ° C. for 16 hours in an oxygen atmosphere.
- target red phosphor particles were obtained.
- the obtained red phosphor particles were subjected to X-ray diffraction measurement, it was confirmed that magnesium titanate was obtained.
- SEM images of the red phosphor particles are shown in FIGS. 1 (a) and 1 (b). Further, the average particle diameter, sphericity, unevenness and BET specific surface area of the red phosphor particles were measured by the method described above. The results are shown in Table 1 below.
- the red phosphor particles had a Si content of 110 ppm.
- Example 1 red phosphor particles were obtained in the same manner as in Example 1 except that the firing temperature was 1200 ° C. When the obtained red phosphor particles were subjected to X-ray diffraction measurement, it was confirmed that magnesium titanate was obtained. SEM images of the red phosphor particles are shown in FIGS. 2 (a) and 2 (b). Further, the average particle diameter, sphericity, unevenness and BET specific surface area of the red phosphor particles were measured by the method described above. The results are shown in Table 1 below.
- Example 2 In Example 1, instead of obtaining spherical particles using a spray dryer, red phosphor particles were obtained in the same manner as in Example 1 except that the wet pulverized slurry was allowed to stand and dry. When the obtained red phosphor particles were subjected to X-ray diffraction measurement, it was confirmed that magnesium titanate was obtained. An SEM image of the red phosphor particles is shown in FIG. Further, the average particle diameter, sphericity, unevenness and BET specific surface area of the red phosphor particles were measured by the method described above. The results are shown in Table 1 below.
- the red phosphor particles of Example 1 are spherical compared to the red phosphor particles of Comparative Examples 1 and 2, and It can be seen that no grain boundary between the primary particles is observed on the particle surface. Although the red phosphor particles of Comparative Example 1 are spherical, grain boundaries between primary particles are observed on the surface. The red phosphor particles of Comparative Example 2 have an irregular shape although no grain boundary between primary particles is observed on the surface.
- the red phosphor particles of Example 1 (product of the present invention) have higher internal quantum efficiency and relative emission intensity than the red phosphor particles of Comparative Examples 1 and 2. It turns out that it is a thing.
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Abstract
Description
M2TiO4 (1)
(式中、Mは1種又は2種以上のアルカリ土類金属元素を示す。)で表されるチタン酸塩にMnを賦活してなり、複数の一次粒子が合一して球状を呈し、かつ3000倍の倍率で電子顕微鏡観察したときに、表面に一次粒子間の粒界が観察されない表面状態となっていることを特徴とする赤色蛍光体粒子を提供するものである。
である。その例としてはカルシウム、マグネシウム、ストロンチウム、バリウムが挙げられる。これらのアルカリ土類金属元素のうち、特にマグネシウムを用いると、赤色蛍光体の発光強度が極めて高くなるので好ましい。一般式(1)中、Mが2種以上のアルカリ土類金属元素であるときは、一般式(1)はMI x1MII x2・・・MN xnTiO4となり、X1、X2、・・・XnはX1+X2+・・・+Xn=2を満たす正数である。
水酸化マグネシウム(平均粒径0.57μm)、酸化チタン(平均粒径0.64μm、Si含有量43ppm)及び炭酸マンガン(平均粒径5.2μm)を、マグネシウム:チタン:マンガンのモル比が2:0.996:0.004となるように秤量しタンクに仕込んだ。タンクに水と分散剤(花王(株)製、ポイズ2100)を加え、固形分濃度が15%の混合液を調製した。分散剤の濃度は2%であった。
実施例1において、焼成温度を1200℃とする以外は実施例1と同様にして赤色蛍光体粒子を得た。得られた赤色蛍光体粒子についてX線回折測定を行ったところ、チタン酸マグネシウムが得られていることを確認した。この赤色蛍光体粒子のSEM像を図2(a)及び(b)に示す。また、この赤色蛍光体粒子の平均粒径、真球度、凹凸度及びBET比表面積を、先に述べた方法で測定した。それらの結果を以下の表1に示す。
実施例1において、スプレードライヤーを用いて球状粒子を得る代わりに、湿式粉砕スラリーを静置乾燥する以外は実施例1と同様にして赤色蛍光体粒子を得た。得られた赤色蛍光体粒子についてX線回折測定を行ったところ、チタン酸マグネシウムが得られていることを確認した。この赤色蛍光体粒子のSEM像を図3に示す。また、この赤色蛍光体粒子の平均粒径、真球度、凹凸度及びBET比表面積を、先に述べた方法で測定した。それらの結果を以下の表1に示す。
実施例及び比較例で得られた赤色蛍光体粒子について、以下の方法で励起波長460nmでの内部量子効率及び相対発光強度を測定した。それらの結果を以下の表1に示す。
日立ハイテク社製の蛍光分光光度計(F-7000)と付属の積分球を用いて励起光460nmとし、430から800nmの範囲を走査し変換効率を求めた。なお全散乱光を測定するための試料には、酸化アルミニウム粉末を用いた。酸化アルミニウムによって得られた450から475nmのスペクトル強度積分値を励起光量とし、蛍光体試料によって得られた450から475nmのスペクトル強度積分値を吸収後励起光量とし、蛍光体試料により得られた600から750nmのスペクトル強度積分値を蛍光量として求めた。そして、以下の式から内部量子効率を求めた
内部量子効率(%)=100×蛍光量÷(励起光量-吸収後励起光量)。
内部量子効率と同じく、蛍光分光光度計を用いて励起光460nmとし、500から800nmの範囲を走査し蛍光スペクトルを得た。得られた強度値から最大発光強度を1.0とし相対発光強度を求めた。
Claims (11)
- 下記一般式(1)
M2TiO4 (1)
(式中、Mは1種又は2種以上のアルカリ土類金属元素を示す。)で表されるチタン酸塩にMnを賦活してなり、複数の一次粒子が合一して球状を呈し、かつ3000倍の倍率で電子顕微鏡観察したときに、表面に一次粒子間の粒界が観察されない表面状態となっていることを特徴とする赤色蛍光体粒子。 - 球形度が1.0~1.8である請求項1記載の赤色蛍光体粒子。
- 表面の凹凸度が1.0~1.25である請求項1又は2記載の赤色蛍光体粒子。
- 平均粒径が1~30μmである請求項1ないし3のいずれかに記載の赤色蛍光体粒子。
- Si含有量が24000ppm以下である請求項1ないし4のいずれかに記載の赤色蛍光体粒子。
- 式(1)中のMがマグネシウムである請求項1ないし5のいずれかに記載の赤色蛍光体粒子。
- 請求項1記載の赤色蛍光体粒子の製造方法であって、
アルカリ土類金属源、マンガン源及びチタン源を分散媒と混合した混合液を調製し、この混合液をメディアミルによって湿式混合し、混合液をスプレードライ法に付して乾燥粉体となし、この乾燥粉体を焼成して焼成体を得たあと、該焼成体をアニール処理することを特徴とする赤色蛍光体粒子の製造方法。 - 乾燥粉体の平均粒径が1~50μmとなるようにスプレードライ法を行う請求項7記載の製造方法。
- アニール処理を500~800℃、1~24時間で行う請求項7又は8記載の製造方法。
- チタン源として、Si含有量が9000ppm以下の酸化チタンを使用する請求項7ないし9のいずれかに記載の製造方法。
- 請求項1ないし6のいずれかに記載の赤色蛍光体粒子を用いたことを特徴とする発光素子。
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CN106574181B (zh) | 2014-08-07 | 2020-10-16 | 三菱化学株式会社 | 荧光体、发光装置、图像显示装置及照明装置 |
CN106433643B (zh) * | 2016-09-29 | 2018-06-29 | 湘潭大学 | 一种钛酸盐近红外荧光粉及其制备方法 |
CN106701073B (zh) * | 2017-01-06 | 2018-12-04 | 江苏师范大学 | 一种Mn4+离子掺杂的钛酸盐基红色荧光粉及制备方法 |
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JP2007297643A (ja) * | 2002-12-20 | 2007-11-15 | Toyoda Gosei Co Ltd | 発光体およびこれを用いた光デバイス |
JP2008069334A (ja) * | 2006-09-12 | 2008-03-27 | Jiaotong Univ | 高飽和赤色発光Mn(IV)活性蛍光体およびその製造方法 |
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JP2007297643A (ja) * | 2002-12-20 | 2007-11-15 | Toyoda Gosei Co Ltd | 発光体およびこれを用いた光デバイス |
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