JP2023167885A - β SIALON PHOSPHOR PARTICLE, β SIALON PHOSPHOR POWDER, LIGHT-EMITTING DEVICE AND METHOD FOR PRODUCING β SIALON PHOSPHOR PARTICLE - Google Patents

Abstract

To provide a β sialon phosphor that is resistant to thermal degradation.SOLUTION: A β sialon phosphor particle includes at least one selected from the group consisting of metal oxide fine particles and metal hydroxide fine particles, which adhere to parts of its surface. Typically, the fine particles are present discontinuously on parts of the surface of the β sialon phosphor particle. The fine particles may be chemically bonded to the β sialon phosphor particle, and may not be chemically bonded thereto.SELECTED DRAWING: Figure 4

Description

The present invention relates to β-sialon phosphor particles, β-sialon phosphor powder, light emitting devices, and methods for producing β-sialon phosphor particles.

Various developments have been carried out on β-sialon phosphors with the intention of applying them to wavelength conversion materials that convert short-wavelength light (typically blue light) into long-wavelength light. ing.

As an example, Patent Document 1 discloses that a first heat-treated product obtained by heat-treating a composition containing silicon nitride containing aluminum, oxygen atoms, and europium is mixed with an aqueous sodium hydroxide solution, and a first heat-base treatment is performed in the atmosphere. , a method for producing a β-sialon phosphor is described, which further comprises performing a second thermal base treatment in a nitrogen atmosphere.

As another example, Patent Document 2 describes a β-sialon having the general formula: Si _6-Z Al _Z O _Z N _8-Z (0<Z≦0.42) and containing Eu as a solid solution. A β-sialon is described in which the 50% area average diameter of primary particles of the β-sialon is 5 μm or more.

Japanese Patent Application Publication No. 2017-110206 International Publication No. 2012/011444

While conducting research on improving β-sialon phosphors, the present inventors found that conventional β-sialon phosphors are easily degraded by heat, that is, unintended changes in properties occur when heated. I found out. This may pose a problem in terms of industrial application of the β-sialon phosphor.

The present invention has been made in view of these circumstances. One of the objects of the present invention is to provide a β-sialon phosphor that does not easily deteriorate due to heat.

The present inventors completed the invention provided below and solved the above problems.

1.
β-type sialon phosphor particles having at least one particle selected from the group consisting of metal oxide particles and metal hydroxide particles attached to a part of the surface.
2.
1. β-type sialon phosphor particles according to
β-type sialon phosphor particles, wherein the fine particles have a median diameter of 15 μm or less.
3.
1. or 2. β-type sialon phosphor particles according to
The fine particles contain at least one selected from the group consisting of ZrO ₂ , Al ₂ O ₃ , SiO ₂ , MgO, Gd ₂ O ₃ , Y ₂ O ₃ , ZnO, La ₂ O ₃ and Al(OH) ₃ . Contains β-type sialon phosphor particles.
4.
1. ~3. β-type sialon phosphor particles according to any one of
The amount of the fine particles is 0.001 to 10% by mass of the β-sialon phosphor particles to which the fine particles are attached to the surface of the β-sialon phosphor particles.
5.
1. ~4. A β-sialon phosphor powder comprising the β-sialon phosphor particles according to any one of the above.
6.
5. The β-type sialon phosphor powder described in
Let S ₀ be the BET specific surface area of β-type Sialon phosphor powder (original powder) with no fine particles attached to the surface, and the BET specific surface area of the phosphor powder containing β-type Sialon phosphor particles with fine particles attached to the surface. β-type sialon phosphor powder, in which (S ₁ /S ₀ )×100 is 102% or more, where S ₁ is S 1 .
7.
5. or 6. The β-type sialon phosphor powder described in
β-type sialon phosphor powder having a BET specific surface area S ₁ of 0.38 m ² /g or more.
8.
A light emitting device including a light emitting source and a wavelength conversion member,
The wavelength conversion member includes phosphor powder,
The phosphor powder is 5. ~7. A light emitting device comprising the β-sialon phosphor powder according to any one of the above.
9.
8. The light emitting device according to
A light emitting device in which the light emitting source includes an LED chip that generates light with a wavelength of 300 nm or more and 500 nm or less.
10.
By dry blending the β-type sialon phosphor particles and the fine particles, 1. ~4. A method for producing β-sialon phosphor particles, which comprises producing β-sialon phosphor particles according to any one of the above.

The β-sialon phosphor of the present invention is not easily degraded by heat.

1 is a cross-sectional view schematically showing an example of the structure of a light emitting device. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG. FIG. 7 is an electron microscope image of the β-sialon phosphor of Example 8. FIG.

Embodiments of the present invention will be described in detail below with reference to the drawings.

All drawings are for illustrative purposes only. The shapes and dimensional ratios of each member in the drawings do not necessarily correspond to the actual product.

In the present specification, the notation "X to Y" in the description of numerical ranges refers to not less than X and not more than Y, unless otherwise specified. For example, "1 to 5% by mass" means "1 to 5% by mass".

In this specification, "at least one fine particle selected from the group consisting of metal oxide fine particles and metal hydroxide fine particles" may be simply referred to as "fine particles."

<β-type sialon phosphor particles and phosphor powder>
At least one fine particle selected from the group consisting of metal oxide fine particles and metal hydroxide fine particles is attached to a part of the surface of the β-sialon phosphor particles of this embodiment.
In this embodiment, the fine particles exist discontinuously on a part of the surface of the β-sialon phosphor particles. In other words, the fine particles are "scattered" on the surface of the β-sialon phosphor particles. The fine particles do not continuously cover the entire surface of the β-sialon phosphor particles.
In this embodiment, if the β-sialon phosphor particles and the fine particles are simply in physical contact, the fine particles are considered to be “attached” to the β-sialon phosphor particles. The β-sialon phosphor particles and the fine particles may or may not be chemically bonded.
Incidentally, if the β-sialon phosphor particles and fine particles are in physical contact but not chemically bonded, at least a portion of the fine particles will be "blown away" by, for example, air blowing.

Although the details are unknown, the reason why thermal deterioration of the β-sialon phosphor particles is suppressed by the attachment of fine particles to a part of the surface of the β-sialon phosphor particles is presumed as follows.
Since the β-type sialon phosphor contains a large amount of Si, it is considered that a large amount of Si—OH exists on the surface of the β-type sialon phosphor. It is presumed that when conventional β-sialon phosphors are heated, an unstable oxide layer derived from Si-OH is formed, and this oxide layer leads to a decrease in performance.

In this embodiment, at least one of the fine particles selected from the group consisting of metal oxide fine particles and metal hydroxide fine particles acts like a solid base and interacts with Si-OH to It is presumed that the formation of an unstable oxide layer originating from -OH is suppressed.

Incidentally, since the fine particles are solid and do not volatilize under normal conditions, it is thought that the thermal deterioration suppressing effect will continue for a relatively long period of time in this embodiment.

The explanation regarding the β-sialon phosphor particles of this embodiment will be continued.

・About the β-sialon phosphor particles themselves (β-sialon phosphor particles before fine particles are attached)

The β-sialon phosphor particles are preferably composed of europium-activated β-sialon in which europium is solidly dissolved.
For example, the β-sialon phosphor particles can absorb blue light in the wavelength range of 420 to 480 nm and emit light having a peak wavelength in the range of more than 480 nm and less than 600 nm.

Europium-activated β-type sialon phosphors are typically represented by the general formula Si _6-z Al _z O _z N _8-z :Eu ²⁺ .
In the general formula Si _6-z Al _z O _z N _8-z :Eu ²⁺ , the z value and the europium content are not particularly limited, but the z value is, for example, more than 0 and 4.2 or less, and the β type From the viewpoint of further improving the emission intensity of the Sialon phosphor, it is preferably 0.005 or more and 1.0 or less.
The content of europium in the europium-activated β-sialon phosphor is preferably 0.1 to 2.0% by mass.

The median diameter d50 of the β-sialon phosphor powder, which is an aggregate of β-sialon phosphor particles, is, for example, 0.1 to 50 μm, preferably 0.25 to 40 μm, and more preferably 0.5 to 30 μm. Since the median diameter is not too large, variations in the chromaticity of the emitted light color can be suppressed. Further, by making the median diameter appropriately large, brightness may be improved in some cases.

The median diameter d50 can be a volume-based value measured by a laser diffraction scattering method. The measurement can be performed in accordance with the method for measuring particle size distribution using laser diffraction/scattering method described in JIS R 1629:1997 "Method for measuring particle size distribution using laser diffraction/scattering method for fine ceramic raw materials". As the measuring device, for example, a particle size distribution measuring device (manufactured by Microtrac Bell Co., Ltd., product name: "Microtrac MT3300EX II") can be used.
As a specific measurement procedure, first, 0.1 g of the phosphor to be measured was added to 100 mL of ion-exchanged water, and the mixture was heated using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., product name: "Ultrasonic Homogenizer US-150E"). A measurement sample is prepared by performing a dispersion process for 3 minutes using a chip size of φ20, amplitude of 100%, oscillation frequency of 19.5 KHz, and amplitude of approximately 31 μm. Thereafter, the particle size distribution is measured using a particle size distribution measuring device. d50 is calculated based on the data obtained from the measurement.

Although the method for producing β-sialon phosphor particles is not limited, for example, they can be produced by the following procedure.

First, raw material powders containing silicon, aluminum, and europium are mixed, and the mixture is fired to obtain a fired product (firing step).
Thereafter, the fired product after the firing process is further subjected to post-processing processes such as crushing and pulverizing treatment, classification treatment, annealing treatment, and acid treatment. Post-treatment steps can be performed in any order.

The firing temperature in the firing step is, for example, 1800°C or more and 2100°C or less, preferably 1850°C or more and 2050°C or less. By setting the firing temperature to the above lower limit or higher, the luminescence intensity can be improved. The firing step may be performed multiple times. Moreover, when performing the second and subsequent firings, a part of the raw materials may be added.

The ambient temperature during the annealing process is, for example, 1100°C or more and 1800°C or less, preferably 1300°C or more and 1750°C or less. By setting the annealing temperature to the above lower limit or higher, the luminescence intensity can be improved. By setting the annealing temperature to the above upper limit value or less, an effect of improving crystallinity can be obtained, and a decrease in luminescence peak intensity can be suppressed.

The atmospheric gas during the annealing process is selected from a rare gas such as argon gas that is an element of group 18 of the periodic table, an inert gas such as nitrogen gas, hydrogen gas, or a mixed gas of hydrogen gas and argon gas. .

The effect of improving properties in the annealing process is exhibited under a wide range of atmospheric pressures from reduced pressure to increased pressure, but pressures lower than 1 kPa are not preferable because decomposition of the β-sialon phosphor is accelerated. In addition, by pressurizing the atmosphere, other conditions necessary for producing the annealing effect can be expanded (lower temperature, shorter time), but if the atmospheric pressure is too high, the annealing effect will reach a plateau and Since a special and expensive annealing device is required, in consideration of mass productivity, the preferable atmospheric pressure is 10 MPa or less, more preferably less than 1 MPa.

The treatment time in the annealing step is 1 hour or more and 24 hours or less, preferably 2 hours or more and 10 hours or less, because if it is too short, the effect of improving crystallinity will be low, and if it is too long, the annealing effect will reach a plateau.

Further, the manufacturing method of this embodiment may include an acid treatment step of immersing the β-sialon phosphor in an acid solution after the annealing step. Thereby, the characteristics of the phosphor can be further improved.

The acid treatment step preferably includes a step of immersing the β-sialon phosphor in an acid solution, separating the β-sialon phosphor from the acid using a filter or the like, and washing the separated β-sialon phosphor with water. The acid treatment can remove decomposition products of the β-sialon phosphor crystals produced during the annealing process, thereby improving the fluorescence properties. Acids used for acid treatment include hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, or nitric acid alone or in mixtures, and mixed acids consisting of hydrofluoric acid and nitric acid suitable for removing decomposed products. is preferred. The temperature of the acid solution during the acid treatment may be at room temperature, but in order to enhance the effect of the acid treatment, it is preferably heated to a temperature of 50° C. or higher and 90° C. or lower.

Through the above steps, it is possible to obtain a β-sialon phosphor containing europium as a solid solution.
Known steps may be added as necessary. For example, post-treatments such as crushing/disintegrating treatment, purification treatment, drying treatment, sieving/classification treatment, etc. may be performed. The step of adjusting the particle size, such as sieving and classification treatment, may be performed at any time after the firing step, after the annealing step, or after the acid treatment step.

- Fine Particles As the fine particles, any metal oxide fine particles and/or metal hydroxide fine particles, which exhibit a thermal deterioration suppressing effect by adhering to the β-sialon phosphor particles, can be used.

Preferred metal oxide fine particles include ZrO ₂ , Al ₂ O ₃ , SiO ₂ , MgO, Gd ₂ O ₃ , Y ₂ O ₃ , ZnO, La ₂ O ₃ and the like. Among these, ZrO ₂ , Al ₂ O ₃ , MgO and La ₂ O ₃ are particularly preferred.
Preferred metal hydroxide fine particles include Al(OH) ₃ and the like.

The median diameter of the fine particles is preferably 15 μm or less, more preferably 0.001 to 15 μm, and even more preferably 0.002 to 0.2 μm.
Since the median diameter of the fine particles is not too large, it is possible to suppress the fine particles from interfering with light absorption and light emission of the β-sialon phosphor particles, and therefore further improvement of the light emission characteristics can be expected. Furthermore, since the median diameter of the fine particles is not too large, the fine particles tend to stick to the β-sialon phosphor particles and are difficult to separate from them, so it is thought that the effect of suppressing thermal deterioration can be sustained for a long time.
Furthermore, it is believed that by having a suitably large median diameter of the fine particles, the contact area of the fine particles with the β-sialon phosphor particles becomes sufficient, making it easy to obtain a sufficient thermal deterioration suppressing effect.

The median diameter of fine particles can be measured using, for example, a transmission electron microscope (TEM) or dynamic light scattering (DLS). Specifically, when measuring with TEM, the diameters of 100 non-agglomerated particles in the TEM image can be measured to determine the number-based median diameter. Furthermore, when measuring with DLS, the volume-based median diameter can be determined.

The amount of the fine particles is preferably 0.001 to 10% by mass, more preferably 0.001% to 10% by mass, based on the entire β-sialon phosphor particles of this embodiment, on which the fine particles are attached. 0.01 to 5% by weight, more preferably 0.1 to 1% by weight.
When the amount of fine particles is appropriately large, it is easy to obtain a sufficient thermal deterioration suppressing effect.
Since the amount of fine particles is not too large, it is possible to suppress the fine particles from interfering with light absorption and light emission of the β-sialon phosphor particles, so that further improvement in the light emission characteristics can be expected.

-Specific surface area The BET specific surface area of the β-type sialon phosphor particles (to which fine particles are attached) of this embodiment can be an index for further performance improvement. This is because the BET specific surface area is considered to reflect the amount of attached fine particles and the mode of attachment of fine particles.
Specifically, the BET specific surface area of the entire β-sialon phosphor particles (to which fine particles are attached) of this embodiment and the β-sialon phosphor particles (original powder) before fine particles are attached are used as a reference. Further performance improvement may be expected by adjusting the type and amount of fine particles so that the BET specific surface area is within a preferable numerical range.
Incidentally, the object of measurement of the BET specific surface area is usually a powder that is an aggregate of particles. Therefore, the BET specific surface area of the β-sialon phosphor powder containing the β-sialon phosphor particles described above will be explained below.

The BET specific surface area S ₁ of the β-sialon phosphor powder is preferably 0.38 m ² /g or more, more preferably 0.38 m ² /g or more and 20 m ² /g or less, and even more preferably 0.39 m ² /g or more. It is 15 m ² /g or less.

As another point of view _, the ratio of the BET specific surface area S 1 of the β-type Sialon phosphor powder (to which fine particles are attached) to the BET specific surface area S ₀ of the β-type Sialon phosphor powder (original powder) before fine particles are attached. Specifically, (S ₁ /S ₀ )×100 [unit: %] is preferably 102% or more, more preferably 103% or more and 5000% or less, and still more preferably 104% or more and 4000% or less.

For the specific method and conditions for measuring the BET specific surface area, please refer to the description of Examples below.

<Method for producing β-type sialon phosphor particles to which fine particles are attached>
The β-sialon phosphor particles (to which fine particles are attached) of this embodiment are produced by dry blending the β-sialon phosphor particles (to which fine particles are not attached) and fine particles, that is, without using a solvent. It can be manufactured by mixing type sialon phosphor particles and fine particles.

As an apparatus for industrially performing dry blending, a known mixing apparatus can be used. At the laboratory level, dry blending can be performed by placing β-sialon phosphor particles (no fine particles attached) and fine particles in a zippered plastic bag and shaking vigorously.
Specific conditions for dry blending are not particularly limited. As shown in the figures (photographs) of Examples, any conditions can be adopted as long as the fine particles adhere to the surface of the β-sialon phosphor particles.

If the phosphor powder made of β-sialon phosphor particles (to which fine particles are attached) produced through dry blending contains coarse particles, it is preferable to perform an operation such as sieving as appropriate.

<Light-emitting device>
The light emitting device of this embodiment is a light emitting device including a light emitting source and a wavelength conversion member. The wavelength conversion member includes phosphor powder. The phosphor powder includes the β-sialon phosphor particles of this embodiment (the β-sialon phosphor particles described above).

FIG. 1 is a cross-sectional view schematically showing an example of the structure of a light emitting device 10. As shown in FIG.
The light emitting device 10 shown in FIG. 1 includes an LED chip as a light emitting source 12, a first lead frame 13 on which the light emitting source 12 is mounted, a second lead frame 14, and a wavelength conversion member covering the light emitting source 12. 15, a bonding wire 16 that electrically connects the light emitting source 12 and the second lead frame 14, and a synthetic resin cap 19 that covers these. The wavelength conversion member 15 includes a phosphor 18 and a sealing resin 17 that disperses the phosphor 18.

A recess 13b for mounting a light emitting diode chip as the light emitting source 12 is formed in the upper part 13a of the first lead frame 13. The recess 13b has a substantially funnel shape in which the hole diameter gradually increases upward from the bottom surface, and the inner surface of the recess 13b serves as a reflective surface. An electrode on the lower surface side of the light emitting source 12 is die-bonded to the bottom surface of this reflective surface. The other electrode formed on the upper surface of the light emitting source 12 is connected to the surface of the second lead frame 14 via a bonding wire 16.

As the light emitting light source 12, various LED chips can be used. Particularly preferred is an LED chip that emits light with wavelengths from near ultraviolet to blue light ranging from 300 nm to 500 nm.

The phosphor 18 used in the wavelength conversion member 15 of the light emitting device 10 includes β-sialon phosphor particles of this embodiment. In addition, from the viewpoint of controlling the light wavelength of the light emitting device 10, the phosphor 18 includes, in addition to the β-sialon phosphor particles of this embodiment, α-sialon phosphor, KSF-based phosphor, CaAlSiN ₃ , and YAG. It may further contain a phosphor, either alone or as a mixture. Examples of elements dissolved in these phosphors include europium (Eu), cerium (Ce), strontium (Sr), calcium (Ca), and manganese (Mn). These phosphors may be used alone or in combination of two or more.
Among these, as the phosphor used in combination with the β-sialon phosphor, a KSF-based phosphor containing manganese as a solid solution is preferable. By using a combination of the β-sialon phosphor of this embodiment that exhibits green color and the KSF-based phosphor that exhibits red color, it can be suitably used as a backlight LED suitable for, for example, a high color rendering TV.
By combining the light emitting light source 12 and the wavelength conversion member 15, it is possible to emit light with high emission intensity.

In the case of the light emitting device 10 using β-type sialon phosphor particles of the present embodiment, the light emitting light source 12 may emit near-ultraviolet light or visible light containing a wavelength of 300 nm or more and 500 nm or less as an excitation source. , has green emission characteristics with a peak in the wavelength range of 520 nm or more and 550 nm or less. For this reason, a near-ultraviolet LED chip or a blue LED chip and the β-sialon phosphor particles of this embodiment are used as the light-emitting light source 12, and furthermore, a red-emitting phosphor, a blue-emitting phosphor, and a yellow-emitting phosphor having a wavelength of 600 nm or more and 700 nm or less are used. White light can be produced by combining a light-emitting phosphor or an orange-emitting phosphor alone or with a mixture.

The light emitting device 10 includes β-sialon phosphor particles whose thermal deterioration is suppressed. Therefore, the light emitting device 10 is excellent in terms of reliability, for example.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. It should be noted that the present invention is not limited only to the embodiments.

<Production of β-type sialon phosphor>
First, a β-sialon phosphor before fine particles were attached was manufactured as follows.

(1) A container contains 98.2% by mass of silicon nitride (Si ₃ N ₄ ), 1.2% by mass of aluminum nitride (AlN), and 0.6% by mass of europium oxide (Eu ₂ O ₃ ). Each raw material was measured and mixed using a V-type mixer (manufactured by Tsutsui Rikagaku Kikai Co., Ltd.) to obtain a mixture. A raw material composition was obtained by completely passing the obtained mixture through a sieve with an opening of 250 μm to remove aggregates. Aggregates that did not pass through the sieve were crushed and the particle size was adjusted so that they would pass through the sieve.

(2) A cylindrical boron nitride container with a lid (manufactured by Denka Co., Ltd., a molded product whose main component is boron nitride (product name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm) as described above. 200 g of the raw material composition prepared as described above was weighed. Thereafter, this container was placed in an electric furnace equipped with a carbon heater, the temperature was raised to 2000°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG), and the container was heated at a heating temperature of 2000°C for 15 hours (calcination step ). After heating, the sample, which had become loosely aggregated in the container, was taken into a mortar and crushed. After crushing, the powder was passed through a sieve with an opening of 250 μm to obtain a powdery first fired body.

(3) The first fired body was filled into a cylindrical boron nitride container, and the container was placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1450° C. in an argon gas atmosphere (pressure: 0.025 MPaG), and the mixture was heated at a heating temperature of 1450° C. for 5 hours (annealing step). After heating, the loosely aggregated particles in the container were crushed in a mortar and passed through a 250 μm sieve to obtain powder.

(4) The powder obtained in (3) above was mixed with a mixed acid of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) (hydrofluoric acid and nitric acid at a volume ratio of 1%). :1) and acid-treated for 30 minutes while stirring at a temperature of 75°C. After the acid treatment, stirring was terminated and the powder was precipitated, and the supernatant and the fine powder purified by the acid treatment were removed. Then, distilled water was further added and the mixture was stirred again. Stirring was completed, the powder was precipitated, and the supernatant liquid and fine powder were removed. Such operations were repeated until the supernatant liquid became transparent with a pH of 8 or less. The obtained precipitate was filtered, dried, and passed through a sieve with an opening of 250 μm.
In the manner described above, a europium-activated β-type sialon phosphor was obtained.

<Mixing with fine particles by dry blending>
By the following procedure, β-sialon phosphor particles (Examples 1 to 14) to which fine particles were attached were obtained.
(1) The β-sialon phosphor and microparticles produced as described above were placed in a polyethylene zippered bag (trade name “Unipack (registered trademark)”, manufactured by Seisaku Nippon Sha Co., Ltd.). The bag was then shaken vigorously for 1 minute. As a result, fine particles were attached to the surface of the β-sialon phosphor. The type and amount of fine particles were as described in the table below.
(2) After completing the above (1), the β-sialon phosphor taken out from the bag was completely passed through a sieve with an opening of 250 μm.

Incidentally, as a comparative example, the phosphor particles obtained in the above <Production of β-type sialon phosphor> were used as they were.

For reference, an image taken using an electron microscope of the β-sialon phosphor particles of Example 8 is shown. Electron microscopy images were taken at several different locations.
3 is an enlarged image of a portion of FIG. 2, and FIG. 4 is an image of a further enlarged portion of FIG. 2.
6 is an enlarged image of a part of FIG. 5, and FIG. 7 is an image of a further enlarged part of FIG.
9 is an enlarged image of a part of FIG. 8, and FIG. 10 is an image of a further enlarged part of FIG.
12 is an enlarged image of a portion of FIG. 11, and FIG. 13 is an image of a further enlarged portion of FIG. 11.
From these images, it can be seen that fine particles are attached to the surface of the β-sialon phosphor particles of the example.

Incidentally, air was blown onto the β-sialon phosphor particles of Example 8 using a blower commonly used to remove dust from camera lenses. It was confirmed by electron microscopy that the amount of fine particles on the surface of the β-sialon phosphor was clearly reduced in this case. In other words, it was confirmed that at least a portion of the fine particles were not chemically bonded to the β-sialon phosphor, but were merely in contact with it.

<Measurement of BET specific surface area>
In the following manner, the BET specific surface area S ₁ of the phosphor powders containing the β-sialon phosphor particles of Examples 1 to 14 (with fine particles attached) and the β-sialon phosphor particles of Comparative Example 1 are calculated. The BET specific surface area S ₀ was determined.
(1) Measurement method: Krypton gas adsorption method (2) Pretreatment/sampling Fluorescent powder (approximately 0.04 to 0.06 g) is placed in a glass cell, degassed under reduced pressure at 300°C for approximately 5 hours, and then subjected to measurement. did.
(3) Measurement/analysis conditions Measuring device: BELSORP-max manufactured by Bell Japan
Adsorbate: Kr
Dead volume measuring gas: He
Measurement temperature: 77K (liquid nitrogen temperature)
Saturated vapor pressure P ₀ : 0.331kPa
Constant temperature bath/piping temperature: 40℃
Measurement mode: Isothermal adsorption process Measured relative pressure P/P ₀ : Approximately 0 to 0.4
Equilibrium setting time: 180s per relative pressure (180s after reaching equilibrium pressure)
Pretreatment temperature and time: 300℃ x approximately 5 hours, vacuum degassing Sample amount: approximately 0.04 to 0.06g
Specific surface area analysis method: BET multi-point method

<Evaluation: Changes in luminescent properties before and after heat exposure>
First, 4 g of β-type SiAlON phosphor particles of Examples 1 to 14 or Comparative Example and ion-exchanged water were placed in a polyethylene zipper bag (product name: Unipack, model: C-4, manufactured by Seisaku Nippon Sha Co., Ltd.). 0.7 g was added and mixed by hand for 2 minutes so that the water was thoroughly mixed. Here, the reason why the β-sialon phosphor particles are mixed with water is to accelerate the deterioration of the β-sialon phosphor particles.
Thereafter, the mixed sample was placed in a porcelain crucible (manufactured by Kennis Co., Ltd., capacity: 30 mL, with lid), and the temperature was raised from room temperature to 250 °C at a heating rate of 10 °C/min, and then heated at 250 °C for 2 hours. Exposure was made.

Before and after heat exposure, the internal quantum efficiency, diffuse reflectance at a wavelength of 800 nm (800 nm diffuse reflectance), and diffuse reflectance at a wavelength of 500 nm (500 nm diffuse reflectance) of each β-type Sialon phosphor particle were measured.
Specifically, the method for measuring internal quantum efficiency and the method for measuring diffuse reflectance were as follows.

(internal quantum efficiency)
The phosphor particles of each Example and Comparative Example were filled into a concave cell so that the surface was smooth, and the cells were attached to the opening of an integrating sphere. Monochromatic light separated into wavelengths of 455 nm from a light emitting light source (Xe lamp) was introduced into this integrating sphere using an optical fiber as excitation light for the phosphor. This monochromatic light was irradiated onto the phosphor sample, and the fluorescence spectrum of the sample was measured using a spectrophotometer (MCPD-7000, manufactured by Otsuka Electronics Co., Ltd.). From the obtained spectrum data, the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated. 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 fluorescence photons was calculated in the range of 465 to 800 nm.

Furthermore, using the same apparatus, a standard reflector with a reflectance of 99% (Spectralon (registered trademark) manufactured by Labsphere) was attached to the opening of the integrating sphere, and the spectrum of excitation light with a wavelength of 455 nm was measured. At that time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.
Then, the internal quantum efficiency was determined using the formula shown below.
Internal quantum efficiency = {Qem/(Qex-Qref)}×100

(diffuse reflectance)
Measurement was performed using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation with an integrating sphere device (ISV-469) attached.
Baseline correction was performed using a standard reflector (Spectralon), a solid sample holder filled with the β-sialon phosphor of each example or comparative example was set, and the diffuse reflectance was measured in the wavelength range of 500 to 850 nm. Ta. From the data obtained in this measurement, the diffuse reflectance at a wavelength of 800 nm and the diffuse reflectance at a wavelength of 500 nm were determined.

By the way, for the standard sample of β-type Sialon phosphor (manufactured by Sialon Co., Ltd., NIMS Standard Green lot No. NSG1301), the internal quantum efficiency, diffuse reflectance for light with a wavelength of 800 nm, and 500 nm were measured according to the measurement method described above. We measured the diffuse reflectance for light with a wavelength of . As a result, the internal quantum efficiency was 74.8%, the diffuse reflectance for light with a wavelength of 800 nm was 95.7%, and the diffuse reflectance for light with a wavelength of 500 nm was 80.4%.

Various information is summarized in the table below.
In the table below, the unit of 800 nm diffuse reflectance and 500 nm diffuse reflectance is %.

Comparing Examples 1 to 14 with Comparative Examples, it is understood that the attachment of fine particles to β-sialon phosphor particles suppresses changes in characteristics (thermal deterioration) due to heat exposure.
In particular, when ZrO ₂ , Al ₂ O ₃ , MgO or La ₂ O ₃ was used as the fine particles, the internal quantum efficiency exceeded 70% even after heat exposure. It is understood that these fine particles are particularly preferable for suppressing thermal deterioration.

10 Light emitting device 12 Light emitting light source (LED chip)
13 First lead frame 13a Upper part 13b Recess 14 Second lead frame 15 Wavelength conversion member 16 Bonding wire 17 Sealing resin 18 Phosphor (β-type sialon phosphor particles)
19 Cap

Claims (10)

β-type sialon phosphor particles having at least one particle selected from the group consisting of metal oxide particles and metal hydroxide particles attached to a part of the surface. The β-type sialon phosphor particles according to claim 1,
β-type sialon phosphor particles, wherein the fine particles have a median diameter of 15 μm or less. The β-sialon phosphor particles according to claim 1 or 2,
The fine particles contain at least one selected from the group consisting of ZrO ₂ , Al ₂ O ₃ , SiO ₂ , MgO, Gd ₂ O ₃ , Y ₂ O ₃ , ZnO, La ₂ O ₃ and Al(OH) ₃ . Contains β-type sialon phosphor particles. The β-sialon phosphor particles according to claim 1 or 2,
The amount of the fine particles is 0.001 to 10% by mass of the β-sialon phosphor particles to which the fine particles are attached to the surface of the β-sialon phosphor particles. A β-sialon phosphor powder comprising the β-sialon phosphor particles according to claim 1 or 2. The β-type sialon phosphor powder according to claim 5,
Let S ₀ be the BET specific surface area of β-type Sialon phosphor powder (original powder) with no fine particles attached to the surface, and the BET specific surface area of the phosphor powder containing β-type Sialon phosphor particles with fine particles attached to the surface. β-type sialon phosphor powder, in which (S ₁ /S ₀ )×100 is 102% or more, where S ₁ is S 1 . The β-type sialon phosphor powder according to claim 5,
β-type sialon phosphor powder having a BET specific surface area S ₁ of 0.38 m ² /g or more. A light emitting device including a light emitting source and a wavelength conversion member,
The wavelength conversion member includes phosphor powder,
A light emitting device, wherein the phosphor powder includes the β-sialon phosphor powder according to claim 5. The light emitting device according to claim 8,
A light emitting device in which the light emitting source includes an LED chip that generates light with a wavelength of 300 nm or more and 500 nm or less. A method for producing β-sialon phosphor particles, comprising dry blending β-sialon phosphor particles and the fine particles to produce the β-sialon phosphor particles according to claim 1 or 2.

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