JP2019011428A - PRODUCTION METHOD OF Eu-ACTIVATED β TYPE SIALON PHOSPHOR - Google Patents

Abstract

To provide a production method of an Eu-activated β type sialon phosphor, which contributes to promoting grain growth.SOLUTION: The production method of an Eu-activated β type sialon phosphor includes a step of heating a first raw material mixture comprising silicon nitride, an aluminum compound, an europium compound and additive β type sialon. In the above production method, a molar ratio X1 of aluminum atoms to silicon atoms in the additive β type sialon, and a molar ratio X2 of aluminum atoms to silicon atoms included in the raw material other than the additive β type sialon in the first raw material mixture satisfy X2<X1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing an Eu-activated β-sialon phosphor used for a white light emitting diode or the like applied to a backlight light source of a display or a lighting device.

  With the increase in output of white light emitting diodes (white LEDs), there is an increasing demand for heat resistance and durability of phosphors. The application of phosphors using strong nitrides or oxynitrides as a base material is progressing.

  Typical examples of nitride and oxynitride phosphors include sialon, which is a solid solution of silicon nitride. Similar to silicon nitride, sialon has two types of crystal systems, α-type and β-type. For example, α-sialon in which divalent Eu ions are activated as an emission center is excited with a wide wavelength from ultraviolet to blue, and becomes a phosphor that emits yellow light having an emission peak wavelength of 550 to 600 nm. In addition, β-type sialon has also been found to exhibit fluorescence characteristics by adding Mn, Ce, and Eu as emission centers (Patent Document 1).

β-type sialon is a solid solution of β-type silicon nitride in which Al is substituted at the Si position and O is substituted at the N position. Since there are two formula quantities of atoms in the unit cell (unit cell), the general formula is expressed as Si _6-z Al _z O _z N _8-z . Here, the z value is 0 to 4.2, the solid solution range is very wide, and the molar ratio of (Si + Al) / (N + O) needs to be maintained at 3/4.

When a divalent Eu ion is contained in a β-sialon crystal, it is excited by ultraviolet to blue light and becomes a phosphor that emits green light of 520 to 550 nm, and is used as a green light emitting component of a light emitting device such as a white LED. it can. This Eu-activated β-sialon has a relatively sharp emission spectrum among the phosphors activated by Eu ²⁺ , and in particular, backlights for liquid crystal displays that require blue, green, and red narrow-band emission. It is a phosphor suitable for a green light emitting component of a light source.

In order to improve the color reproducibility of the liquid crystal display, it is effective to shorten the emission peak of the Eu-activated β-sialon phosphor and further sharpen the emission spectrum. In Patent Document 2, it is reported that the fluorescence emission is shortened and narrowed by lowering the concentration (z value) of aluminum and oxygen in the β-type sialon crystal. As a method of synthesizing such β-type sialon, by heating the raw material mixture in a nitrogen-containing atmosphere, the single silicon in the raw material mixture is nitrided to Si ₃ N _4, and this is supplied with the Al source and Eu. There is a method of obtaining a phosphor in which Al and Eu are dissolved in a crystal of an oxynitride having a β-type Si ₃ N ₄ crystal structure by reacting a source. However, in this case, the luminous efficiency of the Eu-activated β-sialon phosphor is extremely low, and it is difficult to put it to practical use.

  As a method for improving the light emission efficiency of the Eu-activated β-sialon phosphor, the scattering of excitation light generated on the surface of the phosphor particles can be reduced, and the promotion of grain growth can be easily performed in the grains. As the method, there are a method of devising heating conditions, a method of firing a plurality of times, a method of using a β-sialon phosphor serving as a crystal nucleus as a part of the raw material, and a method of adding a part of the raw material later (Patent Document 3). ~ 6).

Japanese Patent No. 3921545 Japanese Patent No. 5360920 JP 2007-326981 A International Publication No. 2011/058919 JP 2013-173868 A Japanese Patent No. 6020756

  In order to narrow the emission spectrum of the Eu-activated β-sialon phosphor in accordance with the teaching described in Patent Document 2, if the concentration of aluminum or oxygen is lowered, grain growth becomes difficult to proceed, and the conventional method is sufficient. It has been difficult to obtain a phosphor with high luminous efficiency because it is difficult to grow grains. Further, although the techniques described in Patent Documents 3 to 6 can contribute to grain growth, they provide a highly convenient technique that can promote grain growth of Eu-activated β-sialon phosphors by a method different from these techniques. That would be significant.

  In view of the above circumstances, an object of the present invention is to provide a method for producing an Eu-activated β-sialon phosphor that contributes to the promotion of grain growth.

  As a result of intensive studies, the inventors of the present invention added β-sialon having a higher molar ratio of aluminum atoms to silicon atoms than the intended β-sialon to the raw material, and fired by adding β-sialon to the raw material. It was found that the luminous efficiency of the obtained phosphor can be increased by promoting the above. The present invention has been completed on the basis of the above knowledge, and is exemplified as follows.

  In one aspect of the present invention, in the method for producing an Eu-activated β-sialon phosphor including a step of heating a first raw material mixture containing silicon nitride, an aluminum compound, a europium compound, and β-sialon for addition, When the molar ratio of aluminum atom to silicon atom in β-type sialon is X1, and the molar ratio of aluminum atom to silicon atom contained in raw materials other than β-type sialon for addition in the first raw material mixture is X2, X2 <X1 is established. This is a method for producing Eu-activated β-sialon phosphor.

  In an embodiment of the method for producing an Eu-activated β-sialon phosphor according to the present invention, X2 / X1 ≦ 0.9 is established.

  In another embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the content of β-sialon for addition in the first raw material mixture is 1 to 50% by mass.

In yet another embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the specific surface area of the additive β-sialon is 0.45 m ² / g or less.

  In still another embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the additive β-sialon is Eu-activated β-sialon phosphor.

  In yet another embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the additive β-sialon is produced by heating a second raw material mixture containing silicon nitride and an aluminum compound. The silicon nitride used in the first raw material mixture has a lower oxygen concentration than the silicon nitride used in the second raw material mixture.

  In still another embodiment of the method for producing an Eu-activated β-sialon phosphor according to the present invention, 0.02 ≦ X1 ≦ 0.10.

  In still another embodiment of the method for producing an Eu-activated β-sialon phosphor according to the present invention, 0.01 ≦ X2 ≦ 0.05.

In still another embodiment of the method for producing an Eu-activated β-sialon phosphor according to the present invention, the Eu-activated β-sialon phosphor has a β-type sialon host crystal represented by the following formula.
Si _6-z Al _z O _z N _8-z
(Wherein 0.02 ≦ z ≦ 0.8)

  In still another embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the 50% diameter in the volume-based integrated fraction by the laser diffraction scattering method according to JIS R1629-1997 is 15 μm or more. It is.

  According to the method for producing an Eu-activated β-sialon phosphor according to the present invention, the light emission efficiency of the Eu-activated β-sialon phosphor can be improved. In addition, when the phosphor manufactured by the manufacturing method of the present invention is used, the luminance of the light emitting device can be increased.

  According to the present invention, an Eu-activated β-sialon phosphor having a narrow emission spectrum and a high emission efficiency is obtained because phosphor grains grow rapidly even when the molar ratio of Al to Si is low. Can be manufactured with high production efficiency. Therefore, the present invention is particularly advantageous when it is required to reduce the molar ratio of Al to Si in order to narrow the emission spectrum of the Eu-activated β-type sialon phosphor.

It is a figure which shows the emission spectrum of the Eu activation beta type sialon fluorescent substance of an Example and a comparative example. FIG. 3 is a diagram showing images of a scanning electron microscope (SEM) showing the microstructures of Eu-activated β-sialon phosphors of Example 1 and Comparative Example 1.

  Hereinafter, a method for producing an Eu-activated β-sialon phosphor according to the present invention will be described based on embodiments. However, the embodiment described below exemplifies a manufacturing method for embodying the technical idea of the present invention, and the present invention is not limited to the following embodiment.

  In one embodiment of the method for producing Eu-activated β-sialon phosphor according to the present invention, the method includes a step of heating a first raw material mixture containing silicon nitride, an aluminum compound, a europium compound, and β-sialon for addition. . A separately prepared β-sialon is used in advance.

  Assuming that the molar ratio of aluminum atoms to silicon atoms in the β-sialon for addition is X1, and the molar ratio of aluminum atoms to silicon atoms contained in the raw material other than the β-sialon for addition in the first raw material mixture is X2, X2 <X1 It is important that Although it is not intended that the present invention be limited by theory, the additive β-sialon acts as a crystal nucleus in the heating process, promotes grain growth, has a large grain size, and has high crystallinity. Thus, it is presumed that the effect of increasing the luminous efficiency of the Eu-activated β-sialon phosphor is brought about. Further, it is presumed that by making X2 smaller than X1, material diffusion near the surface of the β-type sialon particles for addition is promoted and grain growth is likely to occur.

  From the viewpoint of enhancing the effect of promoting grain growth, it is preferable that X2 / X1 ≦ 0.9 is satisfied, X2 / X1 ≦ 0.8 is more preferable, and X2 / X1 ≦ 0.7 is satisfied. Is more preferable, and it is even more preferable that X2 / X1 ≦ 0.6 holds. Further, from the viewpoint of not lowering the crystallinity of the portion growing on the crystal nucleus, 0.2 ≦ X2 / X1 is preferably satisfied, more preferably 0.3 ≦ X2 / X1 is satisfied, and Even more preferably, 4 ≦ X2 / X1 holds.

β-type sialon is a solution in which Al is substituted at the Si position of β-type silicon nitride and O is substituted at the N position. Since there are two formula atoms in the unit cell, the general formula is Si _{6− z} Al _z O _z N _8-z Here, the z value is 0 <z ≦ 4.2, and the solid solution range is very wide. An Eu-activated β-sialon phosphor is obtained by dissolving Eu ²⁺ as a luminescence center in the β-sialon host crystal. In the Eu-activated β-sialon phosphor, the fluorescence spectrum varies depending on the z value. As the z value is smaller, the peak of the fluorescence spectrum shifts to the short wavelength side and the half-value width is narrower, which is suitably used as a green phosphor for liquid crystal displays. For this reason, z value becomes like this. Preferably it is 0.8 or less, More preferably, it is 0.5 or less, More preferably, it is 0.3 or less. However, if the z value is too small, the Eu concentration as the activator is low and sufficient fluorescence intensity cannot be obtained, so the z value is preferably 0.01 or more, more preferably 0.02 or more. Even more preferably, it is 0.03 or more.

  X2 is linked to the z value of the target Eu-activated β-sialon phosphor. When the objective is to obtain a low z-value Eu-activated β-sialon phosphor as described above, X2 is 0. .05 or less is preferable, 0.03 or less is more preferable, and 0.02 or less is even more preferable. Moreover, since crystallinity will fall when X2 is too small, it is preferable that X2 is 0.01 or more, It is more preferable that it is 0.015 or more, It is still more preferable that it is 0.025 or more.

  X1 is more closely linked to the z value of the target Eu-activated β-sialon phosphor than X2, and the object is to obtain a low z-value Eu-activated β-sialon phosphor as described above. In this case, X1 is preferably 0.10 or less, more preferably 0.07 or less, and even more preferably 0.05 or less. Further, since β-sialon for addition having a small X1 is difficult to produce, X1 is preferably 0.02 or more, more preferably 0.025 or more, and 0.03 or more. Even more preferred.

  β-sialon can be obtained by heat treatment using silicon nitride and an aluminum compound as raw materials. Oxide components such as surface oxides contained in the raw material in the heating step generate a liquid phase, and silicon, aluminum, and nitrogen dissolve in the liquid phase and precipitate as β-sialon. That is, the amount of oxygen contained in the raw material plays an important role in the production of β-sialon and the grain growth. As can be seen from the above general formula, when the z value is small, the amount of oxygen in the raw material is small, and it is particularly difficult to enlarge the β-type sialon particles.

  However, since the production method of the present invention has a high effect of promoting the grain growth of the phosphor, it is a case where an Eu-activated β-sialon phosphor having a low z value, that is, a ratio of aluminum atoms to silicon atoms is low. Even so, grain growth is promoted by adding β-sialon for addition having a high molar ratio of aluminum atom to silicon atom into the raw material mixed powder, so that Eu-activated β-sialon phosphor having high luminous efficiency can be obtained. It can be manufactured efficiently.

  If the addition amount of the β-sialon for addition is too small, new β-sialon particles that are difficult to progress are generated separately from the β-sialon particles for addition. The content of β-sialon for addition in the raw material mixture is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more. On the other hand, if the additive amount of β-sialon for addition becomes too large, the starting point of grain growth will increase, so the growth of individual particles will be slight, and the effect of adding β-sialon for additive will not be sufficiently obtained. The content of β-sialon for addition in the first raw material mixture is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, It is still more preferable that it is 20 mass% or less.

The β-sialon for addition is made up of single crystal particles that are larger than those in which multiple small primary particles are sintered to form secondary particles, while the size affects the final phosphor particle size. Is preferred. For this reason, the specific surface area serving as an index of the particle size is preferably 0.45 m ² / g or less, more preferably 0.3 m ² / g or less, and 0.2 m ² / g or less. Even more preferred. However, the specific surface area is preferably 0.01 m ² / g or more, more preferably 0.03 m ² / g or more because the particle size of the phosphor becomes too large if the specific surface area becomes too small. It is even more preferable that it is 0.05 m ² / g or more. In the present invention, the specific surface area is a value measured by a constant volume gas adsorption method (JIS R1626 1996) and calculated by BET multipoint analysis.

  The first raw material mixture contains silicon nitride, an aluminum compound, a europium compound, and β-sialon for addition. Each of these is preferably provided in the form of a powder. Silicon nitride and aluminum compounds are used as materials for forming a β-sialon skeleton, and europium compounds are used as materials for forming a luminescent center.

  The silicon nitride used in the first raw material mixture is preferably higher in purity, and inevitably present in a smaller amount of oxygen. The concentration of oxygen contained in silicon nitride is preferably 1.5% by mass or less, and more preferably 1.2% by mass or less. Here, the oxygen concentration in the raw material indicates a value measured by an inert gas melting-non-dispersive infrared absorption method.

  Examples of the aluminum compound used in the first raw material mixture include aluminum-containing oxides, hydroxides, nitrides, oxynitrides, halides, and the like. Aluminum compounds may be used alone or in combination of two or more. In particular, aluminum nitride alone or a combination of aluminum nitride and aluminum oxide is preferably used.

  Examples of the europium compound used in the first raw material mixture include oxides, hydroxides, nitrides, halides and the like containing europium. In particular, europium oxide, europium nitride, and europium fluoride are preferably used. Europium compounds may be used alone or in combination of two or more.

  The β-sialon for addition used in the first raw material mixture can be produced by heating the second raw material mixture containing silicon nitride and an aluminum compound. From the viewpoint of producing a low z-value Eu-activated β-sialon phosphor, the silicon nitride used in the first raw material mixture has a higher oxygen concentration than the silicon nitride used in the second raw material mixture. Preferably it is low. Specifically, the oxygen concentration of silicon nitride used in the first raw material mixture is preferably 0.9 times or less with respect to the oxygen concentration of silicon nitride used in the second raw material mixture, and 0.8 times The following is more preferable. The β-sialon for addition does not necessarily need to be a phosphor, but is preferably an Eu-activated β-sialon phosphor in order to increase the luminous efficiency of the finally obtained phosphor.

  The first raw material mixture can be obtained by a dry mixing method, a wet mixing method in an inert solvent that does not substantially react with each component of the raw material, and then removing the solvent. In addition, as a mixing apparatus, a V-type mixer, a rocking mixer, a ball mill, a vibration mill, etc. are used suitably.

  By filling the first raw material mixture into a material that does not react with the mixed raw material in the firing process, for example, a container made of boron nitride and heating in a nitrogen atmosphere, the crystal growth reaction, the solid solution reaction, etc. are advanced, and Eu activation is performed. A β-type sialon phosphor is obtained. The heating temperature range is preferably in the range of 1850 to 2050 ° C. If the heat treatment temperature is too low, the grain growth of the Eu-activated β-sialon phosphor hardly proceeds and it is difficult to obtain sufficient fluorescence characteristics. If the heat treatment temperature is too high, β-sialon is decomposed and the fluorescence characteristics are deteriorated, which is not preferable.

  The granular or massive sintered body obtained by the heat treatment is predetermined by carrying out the treatment selected from pulverization, pulverization and classification alone, or by appropriately combining these two or more treatments. Eu-activated β-type sialon phosphors of the size In order to suitably use the Eu-activated β-sialon phosphor as an LED phosphor, the average particle size of the Eu-activated β-sialon phosphor is preferably 5 μm or more, and more preferably 10 μm or more. Preferably, it is still more preferably 15 μm or more. In order to suppress color variation of the LED obtained using the phosphor of the present invention, the average particle diameter of the Eu-activated β-sialon phosphor is preferably 35 μm or less, and more preferably 30 μm or less. 27 μm or less is even more preferable. The “average particle diameter” as used herein refers to a 50% diameter in a volume-based integrated fraction by a laser diffraction scattering method according to JIS R1629-1997.

  As a specific processing example, there is a method in which the sintered body is pulverized to a predetermined particle size using a general pulverizer such as a ball mill, a vibration mill, or a jet mill. However, it should be noted that excessive pulverization not only generates fine particles that easily scatter light, but also generates crystal defects on the particle surface, which may cause a decrease in the luminous efficiency of β-sialon. According to the study of the present inventor, β-sialon obtained by pulverization with a jet mill pulverizer finally showed high luminous efficiency.

  The luminous efficiency of the Eu-activated β-sialon phosphor obtained by the above method is further improved by performing the following treatment. By heating the Eu-activated β-sialon phosphor in a rare gas atmosphere, a reducing atmosphere, or in a vacuum, the emission inhibiting factor present in the Eu-activated β-sialon phosphor is made soluble in an acid. After the change, acid treatment is performed. As temperature at the time of heat processing, it can be set as 1200-1600 degreeC, for example. As the light emission inhibiting factor, there are crystal defects and heterogeneous phases that inhibit visible light emission.

  When the heat-treated Eu-activated β-sialon phosphor is acid-treated, the light emission inhibiting factor changed by heating is dissolved and removed, and the fluorescence characteristics are improved. As the acid used for the acid treatment, one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used. In the acid treatment, the Eu-activated β-sialon phosphor subjected to the heat treatment is dispersed in the above-mentioned aqueous solution containing the acid, and the reaction is performed by stirring for several minutes to several hours (eg, 10 minutes to 3 hours). Can be performed. After the acid treatment, it is desirable that the Eu-activated β-sialon particles and the acid be separated with a filter or the like and then washed thoroughly with water.

  The β-sialon for addition can be obtained by a known production method. For example, a method in which a second raw material mixture containing silicon nitride, an aluminum compound and, if necessary, a europium compound is heat-treated in the same manner as in the method for producing the phosphor, and then produced by pulverization, classification, etc. .

In one embodiment of the Eu-activated β-sialon phosphor obtained by the production method according to the present invention, β-sialon having a different composition grows on the particles of β-sialon for addition. Β-sialon phases with different atomic molar ratios are mixed. In β-sialon having a low z composition, the portion grown on the additive β-sialon particles has higher crystallinity than the particles grown by uniform nucleation (no additive β-sialon added), or Eu ²⁺ can be taken in efficiently, and the luminous efficiency is increased.

  The Eu-activated β-sialon phosphor obtained by the production method according to the present invention can be suitably used as a material for a phosphor layer in a light emitting device. The light-emitting element can be applied to a light-emitting device such as a backlight light source of a display or a lighting device. As a light emitting element, what is equipped with the fluorescent substance layer laminated | stacked on LED and the light emission surface side of LED is mentioned, for example. Examples of the LED include an ultraviolet LED or a blue LED that emits light having a wavelength of 350 to 500 nm, and particularly a blue LED that emits light having a wavelength of 440 to 480 nm. In a preferred embodiment, the Eu-activated β-sialon phosphor obtained by the production method according to the present invention is excited at a wide wavelength range from ultraviolet to blue light and exhibits high-luminance green light emission. It can be suitably used as a phosphor of a white LED used as a light source.

  Hereinafter, the present invention will be described in detail based on examples while comparing with comparative examples.

Example 1
<1. Preparation of β-sialon for addition>
Silicon nitride powder-I (SN-E10 grade manufactured by Ube Industries, Ltd., α rate 96%, oxygen concentration 1.1 mass%) 95.4 mass%, aluminum nitride powder (E grade manufactured by Tokuyama Corporation, oxygen concentration 0. 8 mass%) 3.0 mass%, aluminum oxide powder (TM-DAR grade made by Daimei Chemical Co., Ltd.) 0.8 mass%, europium oxide powder (RU grade made by Shin-Etsu Chemical Co., Ltd.) 0.8 mass% Mixing using a type mixer ("S-3" manufactured by Tsutsui Rika Kikai Co., Ltd.), removing the aggregate by removing the aggregated portion of the resulting mixture and passing through a sieve with an opening of 150 μm. A raw material mixed powder for β-sialon was obtained (a molar ratio X1 of aluminum atom to silicon atom in the raw material mixed powder was 0.044).

  The raw material mixed powder thus obtained is filled in a cylindrical boron nitride container with a lid (N-1 grade manufactured by Denka Co., Ltd.), and pressurized nitrogen of 0.8 MPa · G in an electric furnace of a carbon heater. Heat treatment was performed in an atmosphere at 2000 ° C. for 15 hours. The obtained sintered body was a lightly agglomerated lump and could be easily unraveled manually.

The sintered body that had been mildly crushed was passed through a sieve having an opening of 150 μm, and then pulverized by a jet mill pulverizer (model PJM-80SP, manufactured by Nippon Pneumatic Industry Co., Ltd.). The pulverized powder was classified with a sieve having an opening of 45 μm, and the powder that passed through the sieve was designated as β-I powder for addition. The specific surface area of the obtained β-I powder for addition was measured according to JIS R1626 1996 by a constant volume gas adsorption method using a specific surface area measuring apparatus (BELSORP-mini) manufactured by Nippon Bell Co., Ltd., and by BET multipoint analysis. Calculated. As a result, the specific surface area was 0.28 m ² / g. The obtained β-I powder for addition was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα radiation, and as a result, β-sialon was the main phase of the crystal phase. However, there were trace amounts of unidentifiable crystalline heterogeneous phases that did not substantially adversely affect the properties.

<2. Production of Eu-activated β-type sialon phosphor>
Β-I powder for addition 15% by mass, silicon nitride powder-II (HP for PV grade manufactured by HC Starck, α rate 6%, oxygen concentration 0.8% by mass) 82.5% by mass, aluminum nitride powder ( Tokuyama Co., Ltd. E grade, oxygen concentration 0.8 mass%) 1.8 mass%, europium oxide powder (Shin-Etsu Chemical Co., Ltd. RU grade) 0.7 mass% V-type mixer (Tsutsui Rika Instruments Co., Ltd.) "S-3" manufactured by mixing), and agglomeration was removed by passing through a sieve having a mesh size of 150 µm while dissolving the obtained mixture to obtain a raw material mixed powder (excluding β-sialon for addition) The molar ratio X2 of aluminum atoms to silicon atoms in the mixed powder was 0.025, X2 / X1 = 0.57).

  The raw material mixed powder is filled into a cylindrical boron nitride container (N-1 grade manufactured by Denka Co., Ltd.) with a lid, and 12 at 1975 ° C. in a nitrogen atmosphere of 0.8 MPa · G in a carbon heater electric furnace. A heat treatment was performed for a time to obtain a sintered body.

  The obtained sintered body is a lump that is harder than the β-I powder for addition, and this is opened with a high-speed stamp mill (manufactured by Nissho Chemical Co., Ltd., ANS-143PL, light and hammer are made of alumina) with an opening of 1 mm. The pulverization was repeated until it passed through the sieve. The coarsely crushed particles were further pulverized with a roll crusher (manufactured by Makino, MRCA-0, roll is made of alumina), passed through a sieve having an opening of 150 μm, and then pulverized with a jet mill pulverizer.

  The pulverized sintered body is filled into a cylindrical boron nitride container with a lid (N-1 grade manufactured by Denka Co., Ltd.), and heated at 1450 ° C. for 8 hours in an atmospheric pressure argon atmosphere in a carbon heater electric furnace. The obtained powder was stirred at 75 ° C. for 30 minutes in a 1: 1 mixed acid of 50% by mass hydrofluoric acid and 70% by mass nitric acid, washed with water, filtered and dried, and Eu-activated β-sialon phosphor. Got. The obtained Eu-activated β-sialon phosphor was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα rays. As a result, the crystal phase was a β-sialon single phase.

(Comparative Example 1)
An Eu-activated β-sialon phosphor was obtained by the same method as in Example 1 except that the additive β-I powder was not added to the raw material mixed powder.

(Comparative Example 2)
The mixing ratio of the raw material mixed powder for producing the β-sialon for addition was changed to silicon nitride powder-II: aluminum nitride powder: europium oxide powder = 97.1: 2.1: 0.8 (mass%) In the same manner as in Example 1, a β-sialon for addition (referred to as “additional β-II powder”) was prepared (ratio X1 of aluminum atoms to silicon atoms in the raw material mixed powder was 0.025). . The specific surface area of the β-II powder for addition was measured by the same method as in Example 1 and found to be 0.45 m ² / g. The obtained β-II powder for addition was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα ray. As a result, the crystal phase was a β-type sialon single phase. Subsequently, Eu-activated β-sialon phosphor was obtained by the same method as in Example 1 except that the β-I powder for addition in Example 1 was replaced with β-II powder for addition (X2 / X1 = 1). .00). The obtained Eu-activated β-sialon phosphor was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα rays. As a result, the crystal phase was a β-sialon single phase.

(Example 2)
The mixing ratio of the raw material mixed powder for producing the β-sialon for addition was changed to silicon nitride powder-II: aluminum nitride powder: europium oxide powder = 96.6: 2.6: 0.8 (% by mass) In the same manner as in Example 1, β-sialon for addition (referred to as “addition β-III”) was prepared (ratio X1 of aluminum atom to silicon atom in the raw material mixed powder was 0.031). When the specific surface area of β-III for addition was measured in the same manner as in Example 1, it was 0.38 m ² / g. The obtained β-III powder for addition was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα radiation. As a result, the crystal phase was a β-type sialon single phase. Next, an Eu-activated β-sialon phosphor was obtained by the same method as in Example 1 except that the additive β-I powder in Example 1 was replaced with the additive β-III powder (X2 / X1 = 0). .81). The obtained Eu-activated β-sialon phosphor was subjected to powder X-ray diffraction (XRD) measurement using Cu Kα rays. As a result, the crystal phase was a β-sialon single phase.

(Luminescent characteristics)
The emission characteristics of the Eu-activated β-sialon phosphors of Examples 1 and 2 and Comparative Examples 1 and 2 were measured using a spectrofluorometer (manufactured by Hitachi High-Technologies Corporation, F-7000). Specifically, the emission spectrum was measured with an excitation wavelength of 455 nm, and the peak intensity of the obtained emission spectrum was determined. The peak intensity was the relative ratio with reference to Comparative Example 1. FIG. 1 shows the fluorescence spectrum, and Table 1 shows the peak intensity ratios of the examples and comparative examples.

(Average particle size)
The average particle diameter of the Eu-activated β-sialon phosphors of Examples 1 and 2 and Comparative Examples 1 and 2 (referring to 50% diameter (D50) in the volume-based integrated fraction) is based on JIS R1629-1997. The particle size distribution was measured with a laser diffraction scattering method (LS-13 320 type, manufactured by Beckman Coulter, Inc.). The results are shown in Table 1. An electron micrograph (SEM image) of the Eu-activated β-sialon phosphors of Example 1 and Comparative Example 1 is shown in FIG. 2 for reference. Example 1 clearly has a larger primary particle size than Comparative Example 1, which is thought to have led to an improvement in peak intensity.

(Z value)
For the Eu-activated β-sialon phosphors of Examples 1 and 2 and Comparative Examples 1 and 2, Si _6-z Al _z O, which is a general formula indicating β-sialon, based on the amount of Si and Al in the entire phosphor. The z value in _z N _{8-z was} determined by induction plasma (ICP) emission spectroscopy. The results are shown in Table 1.

(Discussion)
When adding β-sialon for addition into the raw material mixture of Eu-activated β-sialon phosphor, the raw material for Eu-activated β-sialon phosphor is more than the molar ratio X1 of aluminum atom to silicon atom in β-sialon phosphor for addition The peak intensity of the emission spectrum of the obtained β-sialon phosphor was significantly improved by lowering the molar ratio X2 of aluminum atoms to silicon atoms contained in the raw material other than β-sialon for addition in the mixture. Furthermore, the effect increased as X2 / X1 decreased.

  In the Eu-activated β-sialon phosphor, when the molar ratio of Al to Si is low (low z composition), grain growth tends to be insufficient, but even in such a case, as verified in the above example, It can be seen that grain growth is sufficiently promoted by adding β-sialon having a high molar ratio of Al to Si (high z composition) in the raw material mixture. Therefore, according to the present invention, it will be understood that an Eu-activated β-sialon phosphor having a narrow emission spectrum and high emission efficiency can be produced with high efficiency.

Claims (10)

  In a method for producing an Eu-activated β-sialon phosphor comprising a step of heating a first raw material mixture containing silicon nitride, an aluminum compound, a europium compound and an additive β-sialon, Eu-activated β-sialon where X2 <X1 is established, where X1 is the molar ratio of aluminum atoms and X2 is the molar ratio of aluminum atoms to silicon atoms contained in the raw material other than the additive β-sialon in the first raw material mixture. A method for producing a phosphor.   The method for producing an Eu-activated β-sialon phosphor according to claim 1, wherein X2 / X1 ≦ 0.9 is established.   The method for producing an Eu-activated β-sialon phosphor according to claim 1 or 2, wherein the content of β-sialon for addition in the first raw material mixture is 1 to 50 mass%. The method for producing an Eu-activated β-sialon phosphor according to any one of claims 1 to 3, wherein the β-sialon for addition has a specific surface area of 0.45 m ² / g or less.   The method for producing Eu-activated β-sialon phosphor according to any one of claims 1 to 4, wherein the β-sialon for addition is Eu-activated β-sialon phosphor.   The method further includes the step of producing a β-sialon for addition by heating a second raw material mixture containing silicon nitride and an aluminum compound, and in the first raw material mixture rather than silicon nitride used in the second raw material mixture The method for producing an Eu-activated β-sialon phosphor according to any one of claims 1 to 5, wherein the silicon nitride used has a low oxygen concentration.   It is 0.02 <= X1 <= 0.10, The manufacturing method of Eu activated beta type sialon fluorescent substance as described in any one of Claims 1-6.   It is 0.01 <= X2 <= 0.05, The manufacturing method of Eu activated beta type sialon fluorescent substance as described in any one of Claims 1-7. The Eu-activated β-sialon phosphor according to any one of claims 1 to 8, wherein the Eu-activated β-sialon phosphor has a β-sialon host crystal represented by the following formula.
Si _6-z Al _z O _z N _8-z
(Wherein 0.02 ≦ z ≦ 0.8)   10. The Eu-activated β-sialon phosphor according to claim 1, wherein a 50% diameter in a volume-based integrated fraction by a laser diffraction scattering method in accordance with JIS R1629-1997 is 15 μm or more. Method.