JP7252186B2 - Phosphor powders, composites and light-emitting devices - Google Patents

Description

The present invention relates to phosphor powders, composites and light emitting devices.

As nitride and oxynitride phosphors, α-SiAlON phosphors activated with specific rare earth elements are known to have useful fluorescence properties and are applied to white LEDs and the like. In the α-type SiAlON phosphor, the Si—N bonds of the α-type silicon nitride crystal are partially replaced with Al—N bonds and Al—O bonds, and a specific element is added between the crystal lattices to maintain electrical neutrality. It has a structure in which (Ca and lanthanide metals other than Li, Mg, Y, or La and Ce) penetrate into the lattice and form a solid solution. Fluorescent properties are exhibited by making a part of the elements that enter into solid solution a rare earth element that serves as a luminescence center. Among them, the α-SiAlON phosphor in which Ca is dissolved and partially substituted with Eu is excited relatively efficiently in a wide wavelength range from ultraviolet to blue, and emits yellow to orange light. As an attempt to further improve the fluorescence properties of such an α-SiAlON phosphor, for example, it has been proposed to select an α-SiAlON phosphor having a specific average particle diameter by a classification process (Patent Document 1). .

JP 2009-96882 A

In recent years, there has been a demand for even higher luminance of white LEDs, and further improvements in the emission characteristics of phosphor powders used in white LEDs have also been demanded.
SUMMARY OF THE INVENTION The present invention has been made in view of the problems described above, and an object of the present invention is to provide a phosphor powder having improved luminous properties.

According to the present invention, the phosphor powder is composed of α-sialon phosphor particles containing Eu, and has a volume-based median diameter (D ₅₀ ) of 10 μm or more and 20 μm or less by a laser diffraction scattering method, and has a wavelength of 600 nm. Provided is a phosphor powder having a diffuse reflectance of light of 93% or more and 99% or less.

Further, according to the present invention, there is provided a composite comprising the phosphor powder described above and a sealing material for sealing the phosphor powder.

Further, according to the present invention, there is provided a light-emitting device including a light-emitting element that emits excitation light and the above-described composite that converts the wavelength of the excitation light.

ADVANTAGE OF THE INVENTION According to this invention, the technique regarding the fluorescent substance powder with which the light emission characteristic improved can be provided.

The relationship between the median diameter (D ₅₀ ) and the diffuse reflectance for light with a wavelength of 600 nm in the conventional phosphor powder, and the median diameter (D ₅₀ ) and the wavelength of 600 nm defined for the phosphor powder of the present embodiment FIG. 2 is a conceptual diagram showing the range of diffuse reflectance for light; 1 is a schematic cross-sectional view showing the structure of a light emitting device according to an embodiment; FIG.

Hereinafter, embodiments of the present invention will be described in detail.

The phosphor powder according to the embodiment is phosphor powder composed of α-sialon phosphor particles containing Eu. The phosphor powder has a volume-based median diameter (D ₅₀ ) of 10 μm or more and 20 μm or less as measured by a laser diffraction scattering method, and a diffuse reflectance of 93% or more and 99% or less for light having a wavelength of 600 nm.

According to the phosphor powder of the present embodiment, the fluorescence characteristics can be improved while maintaining the excitation wavelength range and the fluorescence wavelength range of conventional α-sialon phosphor particles. can improve the emission characteristics of a light-emitting device using the phosphor powder.
As for the reason for this, although the detailed mechanism is not clear, the median diameter is in the range of 10 μm or more and 20 μm or less, and the diffuse reflectance for light with a wavelength of 600 nm is 93% or more and 99% or less. , it is thought that the fluorescence properties of the phosphor powder are improved.

(α-type Sialon phosphor particles)
The Eu-containing α-sialon phosphor particles are composed of the α-sialon phosphor described below.
The α-type SiAlON phosphor has the general formula: (M1 _x , M2 _y , Eu _z ) (Si _12-(m+n) Al _m+n ) (O _n N _16-n ) (where M1 is a monovalent Li element). , M2 are α-sialon phosphors containing an Eu element represented by one or more divalent elements selected from the group consisting of Mg, Ca and lanthanide elements (excluding La and Ce).

The solid-solution composition of the α-sialon phosphor is represented by m and n determined by x, y, and z in the above general formula and the accompanying Si/Al ratio and O/N ratio, where 0≦x<2.0, 0≦y<2.0, 0<z≦0.5, 0<x+y, 0.3≦x+y+z≦2.0, 0<m≦4.0, 0<n≦3.0. In particular, when Ca is used as M2, the α-sialon phosphor is stabilized in a wide composition range, and by substituting a part of it with Eu, which is the emission center, it is excited by light in a wide wavelength range from ultraviolet to blue, A phosphor is obtained which exhibits yellow to orange visible emission.

In general, α-SiAlON phosphors have a second crystalline phase different from the α-SiAlON phosphor and inevitably exist amorphous phases, so the solid-solution composition cannot be strictly specified by composition analysis or the like. . The crystal phase of the α-sialon phosphor is preferably a single α-sialon phase, and may contain other crystal phases such as aluminum nitride or its polytypoid.

In α-sialon phosphor particles, a plurality of equiaxed primary particles are sintered to form massive secondary particles. The primary particles in the present embodiment refer to the smallest particles that can be observed with an electron microscope or the like and can exist independently. The shape of the α-sialon phosphor particles is not particularly limited, and examples thereof include spherical, cubic, columnar, and irregular shapes.

The median diameter (D ₅₀ ) of the phosphor powder of the present embodiment is 10 μm or more, more preferably 12 μm or more. The upper limit of the median diameter ( _D50 ) of the phosphor powder of the present embodiment is 20 µm or less, more preferably 18 µm or less. The median diameter (D ₅₀ ) of the phosphor powder of this embodiment is the size of the secondary particles.

Here, the median diameter (D ₅₀ ) of the phosphor powder means the 50% diameter in the volume-based integrated fraction measured by the laser diffraction scattering method according to JIS R1629:1997.

In addition to the median diameter (D ₅₀ ) being within the above range, the phosphor particles of the present embodiment satisfy the condition that the diffuse reflectance for light with a wavelength of 600 nm is 93% or more and 99% or less. Diffuse reflectance can be measured with a UV-visible spectrophotometer fitted with an integrating sphere device. From the viewpoint of further improving light emission characteristics, the diffuse reflectance for light with a wavelength of 600 nm is more preferably 94% or more and 96% or less.

FIG. 1 shows the relationship between the median diameter (D ₅₀ ) in the conventional phosphor powder and the diffuse reflectance for light with a wavelength of 600 nm, and the median diameter (D ₅₀ ) defined for the phosphor powder of the present embodiment. and a range of diffuse reflectance for light with a wavelength of 600 nm.
According to the knowledge accumulated so far regarding the α-sialon phosphor, in the conventional α-sialon phosphor powder, plotting the diffuse reflectance for light with a wavelength of 600 nm against the median diameter (D ₅₀ ) in FIG. It is located near the curve shown in FIG. On the other hand, in the phosphor powder of the present embodiment, by optimizing the manufacturing method described later, the diffuse reflectance is higher than conventional, 93%, in the range of median diameter (D ₅₀ ) from 10 μm to 20 μm It was found that by adjusting the content to the range of 99% or more, the light emission characteristics can be improved.

In addition, in the phosphor powder of the present embodiment, the median diameter (D ₅₀ ) and the diffuse reflectance are set in the predetermined ranges described above, respectively, and at least one of the following conditions is satisfied, thereby further improving the light emission characteristics. can be done.
(i) When the volume-based cumulative 10% diameter and the volume-based cumulative 90% diameter measured by the laser diffraction scattering method are D ₁₀ and D ₉₀ , respectively, (D ₉₀ −D ₁₀ )/D ₅₀ is 1.0 or more 1 .5 or less (ii) The diffuse reflectance for light with a wavelength of 500 nm is 66% or more and 80% or less (iii) The diffuse reflectance X1 (%) for light with a wavelength of 800 nm and the diffuse reflection for light with a wavelength of 600 nm The difference (X1-X2) from the rate X2 (%) is 3.0 (%) or less

According to the phosphor powder described above, the volume-based median diameter (D ₅₀ ) by the laser diffraction scattering method is in the range of 10 μm or more and 20 μm or less, and the diffuse reflectance for light with a wavelength of 600 nm is 93% or more and 99%. By satisfying both the following ranges, the fluorescence properties can be improved.

(Manufacturing method of phosphor powder)
A method for producing phosphor powder composed of α-sialon phosphor particles of the present embodiment will be described. In the synthesis process of the α-SiAlON phosphor particles, part of the raw material powder reacts mainly to form a liquid phase, and each element moves through the liquid phase, thereby promoting solid solution formation and grain growth.
First, raw materials containing elements constituting Eu-containing α-sialon phosphor particles are mixed. Specifically, in α-sialon phosphor particles with a low oxygen content synthesized using calcium nitride as a calcium raw material, calcium is dissolved in a high concentration. Particularly when the solid solution concentration of Ca is high, a phosphor having an emission peak wavelength on the higher wavelength side (590 nm or more) than the conventional composition using an oxide raw material can be obtained. Specifically, in the general formula, 1.5<x+y+z≦2.0 is preferable. Part of Ca can be replaced with Li, Mg, Sr, Ba, Y and lanthanide elements (excluding La and Ce) to fine-tune the emission spectrum.

Raw material powders other than the above include silicon nitride, aluminum nitride and Eu compounds. The Eu compound includes europium oxide, a compound that becomes europium oxide after heating, and europium nitride, and europium nitride is preferred because it can reduce the amount of oxygen in the system.

When an appropriate amount of α-sialon phosphor particles synthesized in advance is added to the raw material powder, this serves as a starting point for grain growth, and α-sialon phosphor particles having a relatively large minor axis diameter can be obtained. The grain shape can be controlled by changing the morphology.

As a method for mixing the above raw materials, there are a method of dry mixing and a method of wet mixing in an inert solvent which does not substantially react with each component of the raw materials and then removing the solvent. Mixing devices include V-type mixers, rocking mixers, ball mills, and vibration mills. The mixing of calcium nitride, which is unstable in the air, is preferably carried out in a glove box in an inert atmosphere because its hydrolysis and oxidation affect the properties of the synthesized product.

The powder obtained by mixing (hereinafter simply referred to as raw material powder) is filled in a container made of a material having low reactivity with the raw material and the phosphor to be synthesized, such as a boron nitride container, and heated in a nitrogen atmosphere for a predetermined time. Thus, an α-sialon phosphor is obtained. The temperature of the heat treatment is preferably 1650° C. or higher and 1950° C. or lower.

By setting the heat treatment temperature to 1650°C or higher, the amount of remaining unreacted products can be suppressed and the primary particles can be sufficiently grown. can suppress the formation of knots.

From the viewpoint of suppressing sintering between particles during heating, it is preferable to fill the container with the raw material powder so as to be bulky. Specifically, it is preferable to set the bulk density to 0.6 g/cm ³ or less when filling the raw material powder into a container.

The heating time in the heat treatment is 2 hours or more and 24 hours or less as a time range that does not cause problems such as the presence of a large amount of unreacted substances, insufficient growth of primary particles, and sintering between particles. is preferred.

An ingot-shaped α-sialon phosphor is produced by the above-described steps. This ingot-shaped α-SiAlON phosphor is pulverized by a pulverizer such as a crusher, a mortar, a ball mill, a vibration mill, or a jet mill, and then subjected to a sieve classification step after the pulverization treatment, and the D ₅₀ of the secondary particles is It is possible to obtain a phosphor powder composed of α-sialon phosphor particles whose particle size is adjusted. In addition, the _D50 particle size of the secondary particles can be adjusted by dispersing the phosphor powder in the aqueous solution and removing the secondary particles that have a small particle size and are difficult to settle.

A phosphor powder composed of α-sialon phosphor particles according to the embodiment can be produced by carrying out an acid treatment step after carrying out the above-described steps.
In the acid treatment step, for example, the α-sialon phosphor particles are immersed in an acidic aqueous solution. Examples of the acidic aqueous solution include an acidic aqueous solution containing one acid selected from acids such as hydrofluoric acid, nitric acid and hydrochloric acid, and a mixed acid aqueous solution obtained by mixing two or more of the above acids. Among these, a hydrofluoric acid aqueous solution containing hydrofluoric acid alone and a mixed acid aqueous solution obtained by mixing hydrofluoric acid and nitric acid are more preferable. The stock solution concentration of the acidic aqueous solution is appropriately set depending on the strength of the acid used, but is preferably 0.7% or more and 100% or less, more preferably 0.7% or more and 40% or less. The temperature for acid treatment is preferably 25° C. or higher and 90° C. or lower, more preferably 60° C. or higher and 90° C. or lower, and the reaction time (immersion time) is preferably 15 minutes or longer and 80 minutes or shorter.
The median diameter (D ₅₀ ) of the phosphor powder and the diffuse reflectance for light with a wavelength of 600 nm are the degree of pulverization in the pulverization process, the mesh size of the sieve used in the sieve classification process, the stock solution concentration of the acidic aqueous solution used for acid treatment, It can be controlled by optimally adjusting the temperature, reaction time, etc. during the acid treatment. For example, referring to the abundant examples described later, the acid treatment can be carried out by adopting conditions similar to the combination of the conditions of the pulverization process and the sieving process, the concentration of the undiluted solution of the acidic aqueous solution, the temperature during the acid treatment, and the reaction time. Thus, the median diameter (D ₅₀ ) of the phosphor powder and the diffuse reflectance for light with a wavelength of 600 nm can be set to desired values.

(complex)
A composite according to an embodiment includes the phosphor powder described above and a sealing material that seals the phosphor powder. In the composite according to the present embodiment, a plurality of α-sialon phosphor particles described above are dispersed in the sealing material. Materials such as well-known resins and glass can be used as the sealing material. Examples of resins used for the sealing material include transparent resins such as silicone resins, epoxy resins, and urethane resins.

As a method for producing a composite, there is a method in which the phosphor powder according to the embodiment is added to a liquid resin or glass, uniformly mixed, and then hardened by heat treatment.

(light emitting device)
FIG. 2 is a schematic cross-sectional view showing the structure of the light emitting device according to the embodiment. As shown in FIG. 2 , light emitting device 100 includes light emitting element 120 , heat sink 130 , case 140 , first lead frame 150 , second lead frame 160 , bonding wires 170 , bonding wires 172 and composite 40 .

The light emitting element 120 is mounted on a predetermined area on the upper surface of the heat sink 130 . By mounting the light emitting element 120 on the heat sink 130, the heat dissipation of the light emitting element 120 can be enhanced. Note that a package substrate may be used instead of the heat sink 130 .

The light emitting element 120 is a semiconductor element that emits excitation light. As the light emitting element 120, for example, an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less corresponding to near-ultraviolet to blue light can be used. One electrode (not shown) arranged on the upper surface side of the light emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. The other electrode (not shown) formed on the upper surface of the light emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.

The case 140 is formed with a substantially funnel-shaped recess whose hole diameter gradually increases upward from the bottom surface. The light emitting element 120 is provided on the bottom surface of the recess. The wall surface of the recess surrounding the light emitting element 120 serves as a reflector.

The composite 40 is filled in the recess whose walls are formed by the case 140 . The composite 40 is a wavelength conversion member that converts excitation light emitted from the light emitting element 120 into light with a longer wavelength. The composite of the present embodiment is used as the composite 40, and the α-sialon phosphor particles 1 of the present embodiment are dispersed in the sealing material 30 such as resin. The light-emitting device 100 emits a mixed color of light from the light-emitting element 120 and light emitted from the α-sialon phosphor particles 1 that are excited by absorbing the light from the light-emitting element 120 . The light-emitting device 100 preferably emits white light by mixing the light from the light-emitting element 120 and the light emitted from the α-sialon phosphor particles 1 .

In the light-emitting device 100 of the present embodiment, as described above, the phosphor powder composed of the α-sialon phosphor particles 1 has a volume-based median diameter (D ₅₀ ) of 10 μm or more and 20 μm or less according to the laser diffraction scattering method. and that the diffuse reflectance for light with a wavelength of 600 nm is 93% or more and 99% or less, the fluorescence properties of the α-sialon phosphor particles 1 and the composite 40 are improved, and thus the light emitting device The emission intensity of 100 can be improved.

Note that FIG. 2 illustrates a surface-mounted light-emitting device, but the light-emitting device is not limited to the surface-mounted type, and can be shell-type, COB (chip-on-board) type, or CSP (chip-scale package) type. may

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.
Examples of reference forms are added below.
1.
A phosphor powder composed of α-SiAlON phosphor particles containing Eu,
A volume-based median diameter (D ₅₀ ) by a laser diffraction scattering method is 10 μm or more and 20 μm or less,
A phosphor powder having a diffuse reflectance of 93% or more and 99% or less for light having a wavelength of 600 nm.
2.
1. The diffuse reflectance for light with a wavelength of 500 nm is 66% or more and 80% or less. The phosphor powder according to .
3.
The difference (X1-X2) between the diffuse reflectance X1 (%) for light with a wavelength of 800 nm and the diffuse reflectance X2 (%) for light with a wavelength of 600 nm is 3.0 (%) or less1. or 2. The phosphor powder according to .
4.
When the volume-based cumulative 10% diameter and the volume-based cumulative 90% diameter measured by the laser diffraction scattering method are D ₁₀ and D ₉₀ , respectively, (D ₉₀ −D ₁₀ )/D ₅₀ is 1.0 or more and 1.5 or less. 1. to 3. The phosphor powder according to any one of
5.
1. to 4. The phosphor powder according to any one of, a sealing material that seals the phosphor powder,
A complex comprising
6.
a light-emitting element that emits excitation light;
4. converting the wavelength of the excitation light; and a complex according to
A light emitting device.

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

(Example 1)
In the glove box, as the composition of the raw material powder, 62.4 parts by mass of silicon nitride powder (manufactured by Ube Industries, Ltd., E10 grade) and 22.5 parts by mass of aluminum nitride powder (manufactured by Tokuyama Corporation, E grade). , 2.2 parts by mass of europium oxide powder (RU grade manufactured by Shin-Etsu Chemical Co., Ltd.) and 12.9 parts by mass of calcium nitride powder (manufactured by Kojundo Chemical Laboratory Co., Ltd.). A raw material mixed powder was obtained through a nylon sieve. 120 g of the mixed raw material powder was filled into a lidded cylindrical boron nitride container (manufactured by Denka Co., Ltd., N-1 grade) having an internal volume of 0.4 liters.

This raw material mixed powder was heat-treated together with the container in an electric furnace with a carbon heater in an atmospheric pressure nitrogen atmosphere at 1800° C. for 16 hours. Calcium nitride contained in the raw material mixture powder is easily hydrolyzed in the air, so after removing the boron nitride container filled with the raw material mixture powder from the glove box, quickly set it in an electric furnace and immediately evacuate. and prevented the reaction of calcium nitride.

The composite was lightly pulverized in a mortar and passed through a sieve with an opening of 150 μm to obtain a phosphor powder. When the crystal phase of this phosphor powder was examined by powder X-ray diffraction measurement using CuKα rays, the existing crystal phase was Ca-α type sialon containing Eu element (Ca containing α-type sialon).

Next, 3.2 ml of 50% hydrofluoric acid and 0.8 ml of 70% nitric acid were mixed to obtain a mixed stock solution. 396 ml of distilled water was added to the mixed stock solution to dilute the mixed stock solution to a concentration of 1.0% to prepare 400 ml of a mixed acid aqueous solution. To this mixed acid aqueous solution, 30 g of phosphor powder composed of the α-SiAlON phosphor particles described above was added, and the temperature of the mixed acid aqueous solution was kept at 80° C. and immersed for 30 minutes while being stirred at a rotation speed of 450 rpm using a magnetic stirrer. acid treatment was performed. The acid-treated powder was thoroughly washed with distilled water to remove the acid, filtered, dried, and then sieved through a sieve with an opening of 45 μm to obtain a phosphor powder composed of the α-SiAlON phosphor particles of Example 1.

(Example 2)
Instead of the mixed acid aqueous solution used in Example 1, 396 ml of distilled water was added to a mixed stock solution obtained by mixing 1.2 ml of 50% hydrofluoric acid and 2.8 ml of 70% nitric acid, and an aqueous mixed acid solution with a concentration of 1.0% was added. A phosphor powder composed of the α-sialon phosphor particles of Example 2 was produced in the same procedure as in Example 1, except that the particles were prepared.

(Example 3)
Instead of the mixed acid aqueous solution used in Example 1, 380 ml of distilled water was added to a mixed stock solution in which 10 ml of 50% hydrofluoric acid and 10 ml of 70% nitric acid were mixed to prepare an aqueous mixed acid solution with a concentration of 5.0%. A phosphor powder composed of the α-SiAlON phosphor particles of Example 3 was produced in the same manner as in Example 1, except that the phosphor powder was immersed for 30 minutes while maintaining the temperature of the aqueous solution of mixed acid at 30°C. .

(Example 4)
Instead of the mixed acid aqueous solution used in Example 1, 300 ml of distilled water was added to a mixed stock solution in which 50 ml of 50% hydrofluoric acid and 50 ml of 70% nitric acid were mixed to prepare an aqueous mixed acid solution with a concentration of 25%. Phosphor powder composed of α-SiAlON phosphor particles of Example 4 was prepared in the same manner as in Example 1 except that the phosphor powder was immersed for 60 minutes while maintaining the temperature of the aqueous solution at 80°C.

(Comparative example 1)
Instead of the mixed acid aqueous solution used in Example 1, 398 ml of distilled water was added to a mixed stock solution obtained by mixing 1.0 ml of 50% hydrofluoric acid and 1.0 ml of 70% nitric acid, and an aqueous mixed acid solution with a concentration of 0.5% was added. Using the same procedure as in Example 1, except that the temperature of the mixed acid aqueous solution was kept at 80 ° C. and the acid treatment was performed by immersing for 30 minutes while stirring at a rotation speed of 300 rpm using a magnetic stirrer. A phosphor powder composed of the α-sialon phosphor particles of Comparative Example 1 was prepared.
In the method of producing a phosphor powder composed of α-sialon phosphor particles of Comparative Example 1, the concentration of the stock solution of the mixed acid aqueous solution used for the acid treatment was set to the conventional level.

(Comparative example 2)
The mixture obtained in Example 1 was lightly pulverized in a mortar and then ball-milled using φ1 mm zirconia balls, and instead of the mixed acid aqueous solution used, 50 ml of 50% hydrofluoric acid and 50 ml of 70% nitric acid 300 ml of distilled water was added to the mixed stock solution, and an aqueous mixed acid solution with a concentration of 25% was used. A phosphor powder composed of the α-sialon phosphor particles of Comparative Example 2 was produced in the same procedure as in Example 1.

(particle size measurement)
The particle size was measured by a laser diffraction scattering method based on JIS R1629:1997 using Microtrac MT3300EX II (manufactured by Microtrac Bell Co., Ltd.). 0.5 g of phosphor powder was added to 100 cc of ion-exchanged water, and Ultrasonic Homogenizer US-150E (Nippon Seiki Seisakusho Co., Ltd., chip size φ20 mm, Amplitude 100%, oscillation frequency 19.5 KHz, amplitude about 31 μm) was applied for 3 minutes. Dispersion treatment was performed and then particle size measurement was performed with MT3300EX II. A median diameter ( _D50 ) was obtained from the obtained particle size distribution. Also, the volume-based cumulative 10% diameter (D ₁₀ ) and the volume-based cumulative 90% diameter (D ₉₀ ) were obtained, and (D ₉₀ −D ₁₀ )/D ₅₀ was calculated. The results obtained for particle size are shown in Table 1.

(diffuse reflectance)
The diffuse reflectance was measured by attaching an integrating sphere device (ISV-722) to a UV-visible spectrophotometer (V-650) manufactured by JASCO Corporation. Baseline correction was performed with a standard reflector (Spectralon), and a solid sample holder filled with phosphor powder was attached to measure the diffuse reflectance for light with wavelengths of 500 nm, 600 nm, 700 nm and 800 nm. The results obtained for diffuse reflectance are shown in Table 1.

(Luminous properties)
The internal quantum efficiency and the external quantum efficiency of each obtained phosphor powder were measured with a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.) and calculated according to the following procedure.
The concave cell was filled with phosphor powder so as to have a smooth surface, and an integrating sphere was attached. A monochromatic light having a wavelength of 455 nm from a light emission source (Xe lamp) was introduced into this integrating sphere using an optical fiber. A sample of phosphor powder was irradiated with this monochromatic light as an excitation source, and the fluorescence spectrum of the sample was measured.
A standard reflector (Spectralon manufactured by Labsphere) having a reflectance of 99% was attached to the sample portion, 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 nm or more and 465 nm or less.
Phosphor powder composed of α-SiAlON phosphor particles was attached to the sample portion, and the peak wavelength was determined from the spectral data obtained, and the number of excited 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 nm or more and 800 nm or less.
Internal quantum efficiency = (Qem/(Qex-Qref)) x 100
External quantum efficiency = (Qem/Qex) x 100
When the standard sample NSG1301 sold by Sialon Co., Ltd. was measured using the above measurement method, the external quantum efficiency was 55.6% and the internal quantum efficiency was 74.8%. The instrument was calibrated using this sample as a standard. Table 1 shows the results obtained for internal and external quantum efficiencies.

As shown in Table 1, the fluorescence of Examples 1 to 4 satisfying the conditions that the median diameter (D ₅₀ ) is 10 μm or more and 20 μm or less and the diffuse reflectance for light with a wavelength of 600 nm is 93% or more and 99% or less. It was confirmed that the body powder improved both the internal quantum efficiency and the external quantum efficiency as compared with Comparative Examples 1 and 2, which did not satisfy this condition.

1 α-SiAlON Phosphor Particles 30 Sealing Material 40 Composite 100 Light Emitting Device 120 Light Emitting Element 130 Heat Sink 140 Case 150 First Lead Frame 160 Second Lead Frame 170 Bonding Wire 172 Bonding Wire

Claims (8)

A phosphor powder composed of α-SiAlON phosphor particles containing Eu,
The Eu-containing α-sialon phosphor particles have the general formula: (M1 _x , M2 _y , Eu _z )(Si _12-(m+n) Al _m+n )(O _n N _16-n ) (where M1 is 1 a valent Li element, and M2 is one or more divalent elements selected from the group consisting of Mg, Ca and lanthanide elements (excluding La and Ce). In the general formula, 0 ≤ x < 2.0, 0 ≤ y < 2.0, 0 < z ≤ 0.5, 0 < x + y, 0.3 ≤ x + y + z ≤ 2.0, 0 < m ≤ 4.0, 0 < n ≤ 3.0, and has an emission peak wavelength in a wavelength range of 590 nm or more,
A volume-based median diameter (D ₅₀ ) by a laser diffraction scattering method is 10 μm or more and 20 μm or less,
A phosphor powder having a diffuse reflectance of 94 % or more and 99% or less for light having a wavelength of 600 nm. A phosphor powder composed of α-SiAlON phosphor particles containing Eu,
The Eu-containing α-sialon phosphor particles have the general formula: (M1 _x , M2 _y , Eu _z )(Si _12-(m+n) Al _m+n )(O _n N _16-n ) (where M1 is 1 a valent Li element, and M2 is one or more divalent elements selected from the group consisting of Mg, Ca and lanthanide elements (excluding La and Ce). In the general formula, 0 ≤ x < 2.0, 0 ≤ y < 2.0, 0 < z ≤ 0.5, 0 < x + y, 1.5 ≤ x + y + z ≤ 2.0, 0 < m ≤ 4.0, 0 < n ≤ 3.0,
A volume-based median diameter (D ₅₀ ) by a laser diffraction scattering method is 10 μm or more and 20 μm or less,
A phosphor powder having a diffuse reflectance of 94% or more and 99% or less for light having a wavelength of 600 nm . 3. The phosphor powder according to claim 2, which has an emission peak wavelength in a wavelength range of 590 nm or more . Claim 1, 2 or Claim 2, wherein the difference (X1-X2) between the diffuse reflectance X1 (%) for light with a wavelength of 800 nm and the diffuse reflectance X2 (%) for light with a wavelength of 600 nm is 3.0 ( %) or less. 3. The phosphor powder according to 3 . 5. The phosphor powder according to any one of claims 1 to 4, having a diffuse reflectance of 66% or more and 80% or less for light with a wavelength of 500 nm. When the volume-based cumulative 10% diameter and the volume-based cumulative 90% diameter measured by the laser diffraction scattering method are D ₁₀ and D ₉₀ , respectively, (D ₉₀ −D ₁₀ )/D ₅₀ is 1.0 or more and 1.5 or less. The phosphor powder according to any one of claims 1 to 5 , wherein The phosphor powder according to any one of claims 1 to 6 ,
a sealing material that seals the phosphor powder;
A complex comprising a light-emitting element that emits excitation light;
The complex according to claim 7 , which converts the wavelength of the excitation light;
A light emitting device.

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