JP2019199531A - MANUFACTURING METHOD OF β TYPE SIALON PHOSPHOR - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a β-sialon phosphor having high external quantum efficiency and high internal quantum efficiency. A β-sialon raw material mixture containing a first aluminum compound is heat-treated to obtain a first heat-treated product, and at least a second aluminum compound is added to and mixed with the first heat-treated product, and then heat-treated. A second heat treatment step of obtaining a second heat treatment product, which is a method for producing a β-sialon phosphor satisfying the condition of the following formula (1). C1> C2 In the formula (1), C1 is the mass ratio of aluminum to the total mass of the raw materials excluding the intermediate heat-treated product, and C2 is the mass ratio of aluminum in the β-sialon phosphor contained in the final heat-treated product. is there. [Selection diagram] None

Description

  The present invention relates to a method for producing a β-type sialon phosphor.

  A light-emitting device that combines a light-emitting element that emits primary light and a phosphor that absorbs primary light and emits secondary light is expected to have low power consumption, downsizing, high brightness, and wide color reproducibility. It is attracting attention as a light-emitting device of the next generation, and research and development are actively conducted. For example, a white LED (Light LED) that obtains white light by combining a semiconductor light-emitting element that emits blue to violet short-wavelength visible light and a phosphor, and mixing the light emitted from the semiconductor light-emitting element and the light wavelength-converted by the phosphor. Emitting Diode) is disclosed (Patent Document 1).

  In recent years, with the increase in output of white LEDs, demands for the heat resistance and durability of phosphors are increasing, and there is a demand for phosphors that are small in emission intensity drop due to temperature rise and excellent in durability. Therefore, attention has been focused on nitride and oxynitride phosphors typified by β-sialon phosphors having a stable crystal structure.

  The β-type sialon phosphor is prepared by mixing silicon nitride, aluminum nitride, and an optically active element compound such as europium oxide at a predetermined molar ratio and firing the mixture at a temperature of about 2000 ° C. It is known that it is manufactured by pulverization, and is manufactured by further acid treatment of the obtained fired product (Patent Document 2). Also known is a production method in which after firing, refiring or annealing is performed in an inert atmosphere, reducing atmosphere or vacuum at a temperature lower than the firing temperature (Patent Document 3).

Japanese Patent No. 4769132 Japanese Patent No. 4210761 Japanese Patent No. 5508817

In white LEDs used for backlights, illumination, flat panel displays and the like of liquid crystal displays, improvement in luminance is always required. In order to achieve high brightness of the white LED, it is necessary to improve the luminous efficiency (external quantum efficiency and internal quantum efficiency) of the phosphor used in the light emitting device.
However, the above-described conventional manufacturing method has a problem that it is difficult to improve the external quantum efficiency and the internal quantum efficiency of the β-type sialon phosphor.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a β-sialon phosphor having high external quantum efficiency and high internal quantum efficiency.

  As a result of diligent research to solve the above problems, the inventors of the present invention added an aluminum compound that is one of the raw materials of the β-type sialon phosphor in a plurality of times and heat-treated, By controlling the mass proportion of aluminum in the raw material to be greater than the mass proportion of aluminum in the β-type sialon phosphor, it is found that the external quantum efficiency and internal quantum efficiency of the β-type sialon phosphor are improved, The present invention has been completed.

That is, the manufacturing method of the β-type sialon phosphor according to the embodiment of the present invention,
A first heat treatment step of obtaining a first heat-treated product by heat-treating a β-sialon raw material mixture containing the first aluminum compound;
A second heat treatment step of adding a second aluminum compound to the first heat-treated product and then heat-treating to obtain a second heat-treated product, the condition of the following formula (1):
C1> C2 (1)
(Where C1 is the mass ratio of aluminum to the total mass of the raw materials excluding the intermediate heat-treated product, and C2 is the mass ratio of aluminum in the β-sialon phosphor contained in the final heat-treated product).

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of (beta) sialon fluorescent substance with high external quantum efficiency and internal quantum efficiency can be provided.

  Hereinafter, preferred embodiments of the present invention will be specifically described. However, the present invention should not be construed as being limited thereto, and based on the knowledge of those skilled in the art without departing from the gist of the present invention. Various changes and improvements can be made. A plurality of constituent elements disclosed in the embodiments can form various inventions by an appropriate combination. For example, some constituent elements may be deleted from all the constituent elements shown in the embodiments, or constituent elements of different embodiments may be appropriately combined.

A method for producing a β-type sialon phosphor according to an embodiment of the present invention includes a first heat treatment step in which a β-sialon raw material mixture containing a first aluminum compound is heat-treated to obtain a first heat-treated product, and at least the first heat-treated product. A second heat treatment step of adding a second aluminum compound and then heat-treating to obtain a second heat-treated product.
Further, the method for producing the β-type sialon phosphor may further include one or more third heat treatment steps in which at least a third aluminum compound is added to and mixed with the second heat-treated material and then heat-treated to obtain a third heat-treated material. .
Further, the β-sialon phosphor manufacturing method may further include one or more fourth heat treatment steps in which the second heat-treated product or the third heat-treated product is further heat-treated to obtain a fourth heat-treated product.

Here, in this specification, the “β-sialon raw material mixture” means a mixture of raw materials used in the production of a β-type sialon phosphor. The β-type sialon raw material mixture does not include an intermediate heat-treated product (described below).
Further, in this specification, the “first heat treatment step” means a first heat treatment step in which an aluminum compound is added and heat treatment, and the “second heat treatment step” means that a heat treatment is performed by adding an aluminum compound. Means the second heat treatment step, and “third heat treatment step” means the third or more heat treatment step in which the aluminum compound is added and heat treated, and “fourth heat treatment step” It means a heat treatment step in which heat treatment is performed without adding an aluminum compound.
In this specification, “first aluminum compound” means an aluminum compound added in the first heat treatment step, and “second aluminum compound” means an aluminum compound added in the second heat treatment step. The “third aluminum compound” means an aluminum compound added in the third heat treatment step.
In this specification, “first heat-treated product” means a product obtained in the first heat treatment step, and “second heat-treated product” means a product obtained in the second heat treatment step. The “third heat-treated product” means the product obtained in the third heat treatment step, and the “fourth heat-treated product” means the product obtained in the fourth heat treatment step.

In the present specification, the “intermediate heat treatment product” means a “first heat treatment product” when the heat treatment step includes the first heat treatment step and the second heat treatment step, and the heat treatment step includes the first heat treatment step. When the third heat treatment step is included, it means “first heat treatment product and second heat treatment product”, and when the first heat treatment step to the fourth heat treatment step are included as the heat treatment step, “first heat treatment product to third heat treatment step”. When the heat treatment product includes the first heat treatment step, the second heat treatment step, and the fourth heat treatment step, the “heat treatment product” means “first heat treatment product and second heat treatment product”, respectively.
Further, in this specification, the “final heat-treated product” means “second heat-treated product” when the first heat treatment step and the second heat treatment step are included as the heat treatment step, and the first heat treatment step as the heat treatment step. ~ When the third heat treatment step is included, it means “third heat treatment product”, and when the first heat treatment step to the fourth heat treatment step are included as the heat treatment step, “fourth heat treatment product”, the first heat treatment as the heat treatment step In the case of including a process, a second heat treatment process, and a fourth heat treatment process, each means a “fourth heat treatment product”.

The β-sialon raw material mixture is not particularly limited as long as it contains an aluminum compound, but preferably contains silicon nitride, an aluminum compound, and a europium compound. Silicon nitride and an aluminum compound are materials for forming a β-type sialon skeleton, and a europium compound is a material for forming an emission center.
The β-type sialon raw material mixture may further contain β-type sialon. β-type sialon is an aggregate or core material.
The form of each of the above components contained in the β-sialon raw material mixture is not particularly limited, but it is preferable that all of them are powdery.

Although it does not specifically limit as an aluminum compound, For example, the oxide, hydroxide, nitride, oxynitride, halide, etc. which contain aluminum can be mentioned. These can be used alone or in combination of two or more. Among these, it is preferable to use aluminum nitride alone or a combination of aluminum nitride and aluminum oxide.
The first aluminum compound, the second aluminum compound, and the third aluminum compound may be the same or different, but are preferably the same.

  Although it does not specifically limit as a europium compound, For example, the oxide, hydroxide, nitride, oxynitride, halide, etc. which contain europium can be mentioned. These can be used alone or in combination of two or more. Among these, it is preferable to use europium oxide, europium nitride, and europium fluoride alone.

  The aluminum compound is added separately before the heat treatment in a plurality of heat treatment steps. Specifically, the aluminum compound is added before the heat treatment in the first heat treatment step, the second heat treatment step, and the third heat treatment step, respectively. By dividing and adding aluminum by such a method, in the second heat treatment step and the third heat treatment step, a part of aluminum is dissolved in the β-type sialon phosphor, and the remaining aluminum remains as a different phase. Almost all of the foreign phase containing aluminum can be removed by acid treatment or the like. Further, not all of the different phases may be removed, but only a different phase that absorbs excess light may be removed, and another foreign phase that does not absorb excess light may remain. Aluminum may be contained in another heterogeneous phase that does not absorb excess light. In addition, when adding an aluminum compound before the heat processing of the multiple heat processing process, you may add (beta) sialon phosphor raw materials other than an aluminum compound with an aluminum compound. The solid solution aluminum brings the charge balance in the β-type sialon phosphor close to zero, and crystal defects due to unpaired electrons are reduced. That is, the external quantum efficiency and internal quantum efficiency of the β-type sialon phosphor can be improved by increasing the crystallinity of the β-type sialon phosphor and reducing crystal defects that absorb light. In addition, since the solid solution amount of europium increases as the solid solution amount of aluminum in the β-type sialon phosphor increases, the light absorption rate can also be increased. Furthermore, since the amount of europium dissolved in the β-type sialon phosphor increases, the chromaticity x increases and the emission color can be lengthened.

  As described above, the amount of aluminum and europium dissolved in the β-type sialon phosphor is increased by separately adding and heat-treating the aluminum compound before the heat treatment of the plurality of heat treatment steps. The a-axis lattice constant (a-axis length) of the β-type sialon phosphor contained in the heat-treated product is larger than the a-axis lattice constant of the β-type sialon phosphor contained in the heat-treated product used as a raw material before the heat treatment. Become. The c-axis lattice constant (c-axis length) of the β-type sialon phosphor contained in the heat-treated product after the heat treatment is the c-axis of the β-type sialon phosphor contained in the heat-treated product used as a raw material before the heat treatment. It becomes larger than the lattice constant. Specifically, when the first heat treatment step and the second heat treatment step are included as the heat treatment step, (1) the a-axis lattice constant and the c-axis lattice constant of the β-type sialon phosphor contained in the second heat-treated product are: It becomes larger than the a-axis lattice constant and the c-axis lattice constant of the β-type sialon phosphor contained in the first heat-treated product. When the first heat treatment step to the third heat treatment step are included as the heat treatment step, in addition to the above (1), (2) the a-axis lattice constant and c of the β-type sialon phosphor contained in the third heat treatment product The axial lattice constant becomes larger than the a-axis lattice constant and the c-axis lattice constant of the β-type sialon phosphor contained in the second heat-treated product. Moreover, when the first heat treatment step to the fourth heat treatment step are included as the heat treatment step, the above (1) and (2) are obtained. Furthermore, when the first heat treatment step, the second heat treatment step and the fourth heat treatment step are included as the heat treatment step, the above (1) is obtained.

The addition amount of the aluminum compound is controlled so as to satisfy the following formula (1) from the viewpoint of improving the light absorption rate, internal quantum efficiency, and external quantum efficiency of the β-type sialon phosphor.
C1> C2 (1)
In the formula, C1 is a mass ratio of aluminum to the total mass of the raw materials excluding the intermediate heat-treated product, and C2 is a mass ratio of aluminum in the β-type sialon phosphor contained in the final heat-treated product.
When C1 ≦ C2, the light absorption rate, internal quantum efficiency, and external quantum efficiency of the β-type sialon phosphor are not sufficiently improved. From the viewpoint of stably obtaining the above effect, it is preferable that the condition of the following formula (2) is satisfied.
C1> C2 × 1.03 (2)

Moreover, it is preferable that the addition amount of an aluminum compound satisfy | fills the conditions of following formula (3).
C3> C4 (3)
In the formula, C3 is a mass proportion of aluminum in the β-type sialon phosphor in the second heat-treated product, and C4 is a mass proportion of aluminum in the β-type sialon phosphor in the first heat-treated product. When C3 ≦ C4, the light absorption rate, internal quantum efficiency, and external quantum efficiency of the β-type sialon phosphor may not be sufficiently improved.

  In the first heat treatment step, the content of the aluminum compound in the β-type sialon raw material mixture is not particularly limited as long as it satisfies the condition of the above formula (1), but is preferably 0.1 to 4.0% by mass, More preferably, it is 0.5-2.0 mass%.

  In the second heat treatment step, the ratio of the first heat treatment product in the mixture of the first heat treatment product and the second aluminum compound is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably. Is 98 mass% or more. Moreover, the ratio of the 2nd aluminum compound in a mixture is although it does not specifically limit, Preferably it is 20 mass% or less, More preferably, it is 10 mass% or less, More preferably, it is 2 mass% or less.

  In the third heat treatment step, the ratio of the second heat treatment product in the mixture of the second heat treatment product and the third aluminum compound is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably. Is 98 mass% or more. The ratio of the tertiary aluminum compound in the mixture is not particularly limited, but is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 2% by mass or less.

  In the first heat treatment step to the third heat treatment step, the mixture of the raw materials containing the aluminum compound is removed by a dry mixing method or after wet mixing in an inert solvent that does not substantially react with each component of the raw materials. Can be obtained using the method. In addition, although it does not specifically limit as a mixing apparatus, A V-type mixer, a rocking mixer, a ball mill, a vibration mill, etc. can be utilized suitably.

In the first heat treatment step to the third heat treatment step, the heat treatment of the mixture may be performed by filling a mixture made of a material (for example, boron nitride) that does not react with the mixture during the heat treatment and heating in a nitrogen atmosphere. it can. By using such a method, a crystal growth reaction, a solid solution reaction, etc. can be advanced to obtain a β-type sialon phosphor.
Although the heat processing temperature in a 1st heat processing process-a 3rd heat processing process is not specifically limited, It is preferable to set it as the range of 1800-2100 degreeC. When the heat treatment temperature is too low, grain growth of the β-type sialon phosphor hardly proceeds, and the light absorption rate, internal quantum efficiency, and external quantum efficiency may not be sufficiently improved. On the other hand, when the heat treatment temperature is too high, the β-sialon phosphor is decomposed, and the light absorption rate, internal quantum efficiency, and external quantum efficiency may be reduced.
Other conditions such as a temperature raising time, a temperature raising rate, a heating and holding time, and a pressure in the first heat treatment step to the third heat treatment step are not particularly limited, and may be appropriately adjusted according to the raw material to be used. Typically, the heating and holding time is preferably 3 to 30 hours, and the pressure is preferably 0.6 to 10 MPa.

The fourth heat treatment step is a step for promoting particle growth. By performing the fourth heat treatment step, the light absorption rate, the internal quantum efficiency, and the external quantum efficiency of the β-type sialon phosphor can be improved.
In the fourth heat treatment step, a compound containing an element (excluding aluminum) constituting the β-type sialon phosphor may be added and mixed with the second heat treatment product or the third heat treatment product before the heat treatment.
Moreover, you may hold | maintain at a fixed temperature at the time of the cooling after a 4th heat treatment process. By maintaining at a constant temperature, crystal rearrangement occurs, so that the crystallinity of the β-type sialon phosphor is easily improved by reducing crystal defects.
In addition, the heat processing temperature in a 4th heat processing process is not specifically limited, It can carry out on the conditions similar to a 1st heat processing process-a 3rd heat processing process.

  The second heat-treated product, the third heat-treated product, and the fourth heat-treated product are granular or massive sintered bodies. The granular or massive sintered body can be made into a β-sialon phosphor having a predetermined size by using treatments such as crushing, crushing, and classification alone or in combination. As a specific processing method, 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 causes crystal defects on the particle surface, which may cause a decrease in the luminous efficiency of β-sialon. This treatment may be performed after an acid treatment or an alkali treatment described later.

In order to suitably use the β-type sialon phosphor as an LED phosphor, the average particle size of the β-type sialon phosphor is preferably 5 μm or more, and more preferably 10 μm or more. Moreover, in order to suppress the color variation of LED produced using (beta) type | mold sialon fluorescent substance, it is preferable that the average particle diameter of (beta) type | mold sialon fluorescent substance is 40 micrometers or less.
Here, the “average particle diameter” in this specification means a 50% diameter in a volume-based integrated fraction by a laser diffraction scattering method based on JIS R1629: 1997.

  The method for producing a β-type sialon phosphor according to an embodiment of the present invention includes annealing the second heat-treated product, the third heat-treated product, or the fourth heat-treated product at a temperature lower than the heat treatment temperature of each heat treatment step. An annealing step for obtaining By performing the annealing step, the light emission efficiency of the β-type sialon phosphor can be improved. In addition, since rearrangement of elements removes strain and defects, transparency can also be improved. In the annealing step, a heterogeneous phase may be generated, but this can be removed by acid treatment or alkali treatment described later.

The annealing step is preferably performed in an inert gas such as a rare gas or nitrogen gas, a reducing gas such as hydrogen gas, carbon monoxide gas, hydrocarbon gas, ammonia gas, or a mixed gas thereof, or in a vacuum. By performing the annealing step in such an atmosphere, the activator can be reduced.
The annealing step may be performed under atmospheric pressure or under pressure.
Although the heat processing temperature in an annealing process is not specifically limited, 1200-1700 degreeC is preferable and 1300-1600 degreeC is more preferable.

  Further, before the annealing step, other raw materials may be added to and mixed with the second heat-treated product, the third heat-treated product, or the fourth heat-treated product. Other raw materials include, but are not limited to, oxides, nitrides, oxynitrides, fluorides, and chlorides. In particular, the brightness of the β-type sialon phosphor can be improved by adding silica, aluminum oxide, europium oxide, and europium fluoride to each heat-treated product. However, it is desirable that the raw material to be added can be removed by the acid treatment or the alkali treatment after the annealing process for the residue that does not dissolve.

The β-sialon phosphor manufacturing method according to the embodiment of the present invention includes a second heat-treated product, a third heat-treated product, a fourth heat-treated product, or an annealed product, an acidic or alkaline liquid and / or a gas containing fluorine. It is preferable to include the process of making it contact. By performing such a process, it is possible to dissolve and remove the heterogeneous phase (light emission inhibiting factor) generated in the annealing process, etc., so that the light absorption rate, internal quantum efficiency and external quantum efficiency of the β-type sialon phosphor are improved. be able to.
As the acidic liquid, an aqueous solution containing one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used. As the alkaline liquid, an aqueous solution containing at least one alkali selected from potassium hydroxide, aqueous ammonia, and sodium hydroxide can be used.

  The treatment method using an acidic or alkaline liquid is not particularly limited, but the second heat-treated product, the third heat-treated product, the fourth heat-treated product or the annealed product is dispersed in the aqueous solution containing the acid or alkali described above, The reaction can be carried out by stirring for several minutes to several hours (for example, 10 minutes to 6 hours). After this treatment, it is desirable to separate substances other than the β-type sialon phosphor by filtration and wash the substances attached to the β-type sialon phosphor with water.

Examples of the gas containing fluorine include F ₂ , BrF ₃ , BrF ₅ , NH ₄ HF ₂ , NH ₄ F, PF ₃ , PF ₅ , SiF ₄ , SF ₆ , S ₂ F ₁₀ , ClF ₃ , CF ₄ , and CHF _3. , KrF ₂ , XeF ₂ , XeF ₄ , NF _{3 and the} like can be used. These can be used alone or in combination of two or more.

  The β-sialon phosphor produced as described above can be suitably used as a material for the phosphor layer in the 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. Although it does not specifically limit as a light emitting element, It is equipped with LED and the fluorescent substance layer laminated | stacked on the light emission surface side of LED. As the LED, an ultraviolet LED or a blue LED that emits light having a wavelength of 350 to 500 nm, particularly a blue LED that emits light having a wavelength of 440 to 480 nm can be used. In particular, the β-type sialon phosphor obtained by the manufacturing method according to the embodiment of the present invention is excited with a wide wavelength range from ultraviolet to blue light and exhibits high-luminance green light emission. Therefore, blue or ultraviolet light is used as a light source. The phosphor can be suitably used as a white LED phosphor.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
(Example 1-1)
A β-sialon phosphor was obtained by sequentially performing the following first heat treatment step, second heat treatment step, annealing step, and pickling step.
<First heat treatment process>
α-type silicon nitride powder (SN-E10 grade, manufactured by Ube Industries, Ltd.) 98.06% by mass, aluminum nitride powder (E grade, manufactured by Tokuyama Co., Ltd.) 1.34% by mass, europium oxide (RU grade, Shin-Etsu Chemical) (Co., Ltd.) 0.60% by mass was mixed and mixed using a small mill mixer, and then passed through a sieve having an opening of 150 μm to remove aggregates, thereby obtaining a β-sialon raw material mixture. Next, 100 g of the β-type sialon raw material mixture is filled into a cylindrical boron nitride container with a lid (manufactured by DENKA CORPORATION), placed in an electric furnace equipped with a carbon heater, and then in a pressurized nitrogen atmosphere of 0.8 MPa. The first heat-treated product was obtained by performing heat treatment at 2010 ° C. for 20 hours.
<Second heat treatment step>
Next, aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) was added to the first heat-treated product, and mixed using a small mill mixer. Here, the compounding ratio of the aluminum nitride powder in the mixture was 0.20% by mass. Next, this mixture is filled into a cylindrical boron nitride container with a lid (manufactured by DENKA CORPORATION) and placed in an electric furnace equipped with a carbon heater, and then at 2010 ° C. in a pressurized nitrogen atmosphere of 0.8 MPa. A heat treatment was performed for 20 hours to obtain a second heat-treated product. The second heat-treated product was pulverized with an alumina ball mill, and then aggregates were removed through a sieve having an opening of 45 μm.

<Annealing process>
Next, after the second heat-treated product was filled into a cylindrical boron nitride container, an annealed product was obtained by performing heat treatment at 1500 ° C. for 15 hours in an argon-flow atmosphere at atmospheric pressure in a carbon heater electric furnace. .
<Pickling process>
Next, the annealed product was immersed in a mixed acid of hydrofluoric acid and nitric acid at 60 to 70 ° C. for 3 hours, and then filtered to remove the solution. Next, washing with ion-exchanged water was repeated until the ion-exchanged water became neutral, and then filtered and dried. Thereafter, a sieve having an opening of 45 μm was applied.

(Example 1-2)
Β-sialon phosphor under the same conditions as in Example 1-1, except that the blending ratio of the aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) added in the second heat treatment step was changed to 0.40% by mass. Got.

(Example 1-3)
A β-type sialon phosphor was obtained under the same conditions as in Example 1-2 except that the following fourth heat treatment step was added between the second heat treatment step and the annealing step.
<Fourth heat treatment process>
The second heat-treated product is filled into a cylindrical boron nitride container with a lid (manufactured by Denka Co., Ltd.) and placed in an electric furnace equipped with a carbon heater, and then 20 ° C. in a pressurized nitrogen atmosphere of 0.8 MPa at 2010 ° C. Heat treatment was performed for a time to obtain a fourth heat-treated product.

(Example 1-4)
A β-type sialon phosphor was obtained under the same conditions as in Example 1-2 except that the following third heat treatment step was added between the second heat treatment step and the annealing step.
<Third heat treatment process>
Aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) was added to the second heat-treated product and mixed using a small mill mixer. Here, the mixture ratio of the aluminum nitride powder in the mixture was 0.40 mass%. Next, this mixture is filled into a cylindrical boron nitride container with a lid (manufactured by DENKA CORPORATION) and placed in an electric furnace equipped with a carbon heater, and then at 2010 ° C. in a pressurized nitrogen atmosphere of 0.8 MPa. A heat treatment was performed for 20 hours to obtain a third heat-treated product.

(Comparative Example 1-1)
A β-type sialon phosphor was obtained under the same conditions as in Example 1-1 except that aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) was not added in the second heat treatment step.

(Example 2-1)
Except having changed the 1st heat treatment process and the 2nd heat treatment process as follows, beta type sialon fluorescent substance was obtained on the same conditions as Example 1-1.
<First heat treatment process>
α-type silicon nitride powder (SN-E10 grade, manufactured by Ube Industries, Ltd.) 98.78% by mass, aluminum nitride powder (E grade, manufactured by Tokuyama Co., Ltd.) 0.62% by mass, europium oxide (RU grade, Shin-Etsu Chemical) (Co., Ltd.) 0.60% by mass was mixed and mixed using a small mill mixer, and then passed through a sieve having an opening of 150 μm to remove aggregates, thereby obtaining a β-sialon raw material mixture. Next, 100 g of the β-type sialon raw material mixture is filled into a cylindrical boron nitride container with a lid (manufactured by DENKA CORPORATION), placed in an electric furnace equipped with a carbon heater, and then in a pressurized nitrogen atmosphere of 0.8 MPa. The first heat-treated product was obtained by performing heat treatment at 2010 ° C. for 20 hours.
<Second heat treatment step>
Next, aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) was added to the first heat-treated product, and mixed using a small mill mixer. Here, the compounding ratio of the aluminum nitride powder in the mixture was 0.90% by mass. Next, this mixture is filled into a cylindrical boron nitride container with a lid (manufactured by DENKA CORPORATION) and placed in an electric furnace equipped with a carbon heater, and then at 2010 ° C. in a pressurized nitrogen atmosphere of 0.8 MPa. A heat treatment was performed for 20 hours to obtain a second heat-treated product. The second heat-treated product was pulverized with an alumina ball mill, and then aggregates were removed through a sieve having an opening of 45 μm.

(Comparative Example 2-1)
A β-type sialon phosphor was obtained under the same conditions as in Example 2-1, except that aluminum nitride powder (E grade, manufactured by Tokuyama Corporation) was not added in the second heat treatment step.

The following evaluation was performed on each heat-treated product and β-type sialon phosphor obtained in the above Examples and Comparative Examples.
<External quantum efficiency, intermediate heat efficiency, light absorption rate and internal quantum efficiency of intermediate heat-treated product, final heat-treated product and β-type sialon phosphor>
A standard reflector (Spectralon (registered trademark) manufactured by Labsphere) having a reflectance of 99% was set in the side opening of the integrating sphere. Monochromatic light separated at a wavelength of 455 nm from a light emission source (Xe lamp) was introduced into this integrating sphere with an optical fiber, and the reflected light spectrum was measured with a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). At that time, the excitation light photon number (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.
Next, after filling the concave cell with a β-type sialon phosphor so that the surface is smooth and setting it in the opening of the integrating sphere, the monochromatic light of wavelength 455 nm is irradiated, and the excitation reflected light spectrum is measured with a spectrophotometer It was measured by. The number of excited reflected light photons (Qref) and the number of fluorescent photons (Qem) were calculated from the obtained spectrum data. The number of excitation reflected light photons was calculated in the same wavelength range as the number of excitation light photons, and the number of fluorescent photons was calculated in the range of 465 to 800 nm. Based on the following formulas, the external quantum efficiency, the light absorption rate, and the internal quantum efficiency were calculated from the obtained three types of photons.
External quantum efficiency = (Qem / Qex) × 100
Light absorption rate = (Qref / Qex) × 100
Internal quantum efficiency = external quantum efficiency / light absorption rate When a standard sample (NIMS Standard Green lot No. NSG1301, manufactured by Sialon) of a β-type sialon phosphor is measured by the above measurement method, the external quantum efficiency is 55.6. %, Optical absorptance of 74.4%, and internal quantum efficiency of 74.8%. Quantum efficiency and optical absorptance may fluctuate when the manufacturer and manufacturing lot number of the measuring device change. If the manufacturer and manufacturing lot number of the measuring device changes, the β-type sialon phosphor The measurement data is corrected using the standard sample as a reference value.

<600 nm light absorption rate of β-type sialon phosphor>
A standard reflector (Spectralon (registered trademark) manufactured by Labsphere) having a reflectance of 99% was set in the side opening of the integrating sphere. Monochromatic light separated at a wavelength of 600 nm from an emission light source (Xe lamp) was introduced into this integrating sphere with an optical fiber, and the reflected light spectrum was measured with a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). At that time, the number of incident light photons (Qex (600)) was calculated from the spectrum in the wavelength range of 590 to 610 nm.
Next, after filling the concave cell with a β-type sialon phosphor so that the surface is smooth and setting it in the opening of the integrating sphere, monochromatic light with a wavelength of 600 nm is irradiated, and the incident reflected light spectrum is measured with a spectrophotometer. It was measured by. The number of incident reflected light photons (Qref (600)) was calculated from the obtained spectrum data. The number of incident reflected light photons (Qref (600)) was calculated in the same wavelength range as the number of incident light photons (Qex (600)). Based on the following formula, the light absorption rate at 600 nm was calculated from the obtained two types of photons.
600 nm light absorption rate = (Qref (600) / Qex (600)) × 100
When a standard sample of β-sialon phosphor (NIMS Standard Green lot No. NSG1301, manufactured by Sialon) was measured by the above measurement method, the light absorption rate at 600 nm was 7.6%. Absorption rate of 600nm may change when the manufacturer of the measurement device, production lot number, etc. changes, so if the manufacturer of the measurement device, production lot number, etc. changes, a standard sample of β-type sialon phosphor The measurement data is corrected using as a reference value.

<Chromaticity x of intermediate heat-treated product, final heat-treated product and β-type sialon phosphor>
The chromaticity x is a value of CIE1931, and was measured with a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). In the same manner as above, monochromatic light with a wavelength of 455 nm was irradiated, the excitation reflected light spectrum was measured in the range of 465 to 800 nm, and the chromaticity x was calculated.
When a standard sample of β-sialon phosphor (NIMS Standard Green lot No. NSG1301, manufactured by Sialon) was measured by the above-described measurement method, the chromaticity x was 0.356. The value of chromaticity x may change when the manufacturer of the measurement device, the production lot number, etc. changes. Therefore, if the manufacturer of the measurement device, the production lot number, etc. are changed, a standard sample of β-sialon phosphor should be used. The measurement data is corrected as a reference value.

<A-axis lattice constant and c-axis lattice constant of intermediate heat-treated product, final heat-treated product and β-type sialon phosphor>
Each heat-treated product and β-type sialon phosphor were subjected to powder X-ray diffraction using CuKα rays using an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation). From the obtained X-ray diffraction pattern, the a-axis lattice constant (lattice constant a-axis length) and c-axis lattice constant (lattice constant c-axis length) were calculated by the Liberty analysis method.

<Al content in β-sialon phosphor contained in each heat-treated product>
The heat-treated product was immersed in a mixed acid of hydrofluoric acid and nitric acid (60 to 70 ° C.) for 3 hours, and then filtered to remove the solution. Next, washing with ion-exchanged water was repeated until the ion-exchanged water became neutral, and then filtered and dried. Next, after the dried product was melted, the amount of Al in the β-sialon phosphor contained in the heat-treated product was measured using an ICP emission spectrometer (ICPE-9000, manufactured by Shimadzu Corporation).

<Average particle diameter D50 of intermediate heat-treated product, final heat-treated product and β-type sialon phosphor>
Based on JIS R1629: 1997, the 50% diameter in the volume-based integrated fraction was measured using a laser diffraction scattering method.

  Each evaluation result is shown in Table 1.

As shown in Table 1, when the aluminum nitride powder (aluminum compound), which is one of the raw materials of β-type sialon phosphor, is added in a plurality of times and heat-treated, the aluminum in the raw material excluding the intermediate heat-treated product In Examples 1-1 to 1-4 and 2-1, in which the mass ratio was controlled to be larger than the mass ratio of aluminum in the β-type sialon phosphor, the aluminum nitride powder (aluminum compound) was divided into a plurality of times. As compared with Comparative Examples 1-1 and 2-1, which were not added, the internal quantum efficiency and the external quantum efficiency of the β-type sialon phosphor were improved. Moreover, in Examples 1-1 to 1-4 and 2-1, it was confirmed that the light absorption rate slightly increased as compared with Comparative Examples 1-1 and 2-1.
Further, comparing Example 1-1 and Example 1-2, when the amount of aluminum nitride powder (aluminum compound) blended in the second heat treatment step is increased, the internal quantum efficiency and external quantum of the β-type sialon phosphor are increased. A tendency for efficiency and light absorption to increase was confirmed.

  As described above, according to the present invention, it is possible to provide a method for producing a β-sialon phosphor having high external quantum efficiency and high internal quantum efficiency.

Claims (12)

A first heat treatment step of obtaining a first heat-treated product by heat-treating a β-sialon raw material mixture containing the first aluminum compound;
A second heat treatment step of adding a second aluminum compound to the first heat-treated product and then heat-treating to obtain a second heat-treated product, the condition of the following formula (1):
C1> C2 (1)
(Where C1 is the mass ratio of aluminum to the total mass of the raw materials excluding the intermediate heat-treated product, and C2 is the mass ratio of aluminum in the β-sialon phosphor contained in the final heat-treated product). A method for producing a β-type sialon phosphor.   The β-sialon phosphor according to claim 1, further comprising at least one third heat treatment step in which at least a third aluminum compound is added to and mixed with the second heat-treated product and then heat-treated to obtain a third heat-treated product. Method.   3. The method for producing a β-type sialon phosphor according to claim 1, further comprising one or more fourth heat treatment steps for further heat treating the second heat treated product or the third heat treated product to obtain a fourth heat treated product. Condition of the following formula (2):
C1> C2 × 1.03 (2)
The manufacturing method of (beta) sialon fluorescent substance as described in any one of Claims 1-3 which satisfy | fills. Condition of the following formula (3):
C3> C4 (3)
(Wherein, C3 is the mass ratio of aluminum in the β-type sialon phosphor contained in the second heat-treated product, and C4 is the mass of aluminum in the β-type sialon phosphor contained in the first heat-treated product. The method for producing a β-sialon phosphor according to any one of claims 1 to 4, which satisfies a ratio).   The β-sialon phosphor according to any one of claims 1 to 5, wherein a ratio of the first heat-treated material in the mixture of the first heat-treated material and the second aluminum compound is 80% by mass or more. Production method.   The first heat treatment step, the second heat treatment step, the third heat treatment step and the fourth heat treatment step are performed at a temperature of 1800 to 2100 ° C in a nitrogen atmosphere. A method for producing the described β-sialon phosphor.   Heat treatment of each heat treatment step in the second heat-treated product, the third heat-treated product or the fourth heat-treated product in an inert gas, in a reducing gas, in a mixed gas of an inert gas and a reducing gas or in a vacuum The method for producing a β-type sialon phosphor according to any one of claims 1 to 7, further comprising an annealing step of obtaining an annealed product by heat treatment at a temperature lower than the temperature.   The method according to claim 1, further comprising contacting the second heat-treated product, the third heat-treated product, the fourth heat-treated product, or the annealing-treated product with an acidic or alkaline liquid and / or a gas containing fluorine. The manufacturing method of the beta-type sialon fluorescent substance as described in any one.   The method for producing a β-type sialon phosphor according to any one of claims 1 to 9, wherein the first aluminum compound, the second aluminum compound, and the third aluminum compound are aluminum nitride.   The a-axis lattice constant of the β-type sialon phosphor contained in the heat-treated product after the heat treatment is larger than the a-axis lattice constant of the β-type sialon phosphor contained in the heat-treated product used as a raw material before the heat treatment. The manufacturing method of the beta-type sialon fluorescent substance as described in any one of 10-10.   The c-axis lattice constant of the β-type sialon phosphor contained in the heat-treated product after the heat treatment is larger than the c-axis lattice constant of the β-type sialon phosphor contained in the heat-treated product used as a raw material before the heat treatment. The manufacturing method of the beta sialon fluorescent substance as described in any one of -11.