阅读说明：本技术 荧光体粒子、复合体、发光装置和荧光体粒子的制造方法 (Phosphor particle, composite, light-emitting device, and method for producing phosphor particle ) 是由 野见山智宏 武田雄介 高村麻里奈 奥园达也 宫崎胜 渡边真太郎 于 2020-03-24 设计创作，主要内容包括：一种含有Eu的α型塞隆荧光体粒子。在该α型塞隆荧光体粒子表面形成有至少一个狭缝。该α型塞隆荧光体粒子优选经过原料的混合工序、加热工序、粉碎工序和酸处理工序来制造。(An alpha-sialon phosphor particle containing Eu. At least one slit is formed on the surface of the alpha-sialon phosphor particle. The α -sialon phosphor particles are preferably produced through a mixing step of raw materials, a heating step, a pulverizing step, and an acid treatment step.)

1. A phosphor particle is an alpha-sialon phosphor particle containing Eu,

at least one slit is formed on the surface of the alpha-sialon phosphor particle.

2. The phosphor particle according to claim 1, wherein a distance from a surface of the α -sialon phosphor particle to a bottom of the slit is 200nm to 1500nm in at least one cross section of the slit.

3. The phosphor particle according to claim 1 or 2, wherein, in at least one cross section of the slit, a width of an opening by the slit formed on the surface of the α -sialon phosphor particle in a direction orthogonal to an extending direction of the slit is 50nm to 500 nm.

4. The phosphor particle according to any one of claims 1 to 3, wherein the slit has a V-shaped cross section in a cross section orthogonal to an extending direction thereof.

5. The phosphor particle according to any one of claims 1 to 4, wherein a plurality of slits are formed in the α -sialon phosphor particle.

6. The phosphor particle according to claim 5, wherein there are a plurality of the slits separated from each other.

7. The phosphor particle according to claim 5 or 6, wherein there are a plurality of the slits intersecting with each other.

8. The phosphor particle according to any one of claims 5 to 7, wherein a plurality of slits radially extending around a branch point are provided.

9. The phosphor particle according to any one of claims 1 to 8, wherein L > P, where P is a maximum diameter in a plan view of the α -sialon phosphor particle and L is a total of path lengths along the slit.

10. The phosphor particle according to any one of claims 1 to 9, wherein the α -sialon phosphor particle is a columnar body, and the slit extends from one end portion to the other end portion of the side surface of the columnar body in the axial direction of the columnar body.

11. The phosphor particle according to any one of claims 1 to 10, wherein the α -type sialon phosphor particle is composed of an α -type sialon phosphor containing Eu element, the α -type sialon phosphor being represented by a general formula: (M1_x，M2_y，Eu_z)(Si_12－(m+n)Al_m+n)(O_nN_16－n) In the general formula, M1 is a 1-valent Li element, M2 is a 2-valent Ca element, x is more than or equal to 0 and less than 2.0, y is more than or equal to 0 and less than 2.0, z is more than 0 and less than or equal to 0.5, x + y is more than 0 and less than or equal to 0.3 and less than or equal to x + y + z and less than or equal to 2.0, M is more than 0 and less than or equal to 4.0, and n is more than 0 and less than or equal to 3.0.

12. The phosphor particle of claim 11, wherein 1.5 < x + y + z ≦ 2.0.

13. The phosphor particle according to claim 11 or 12, wherein 0. ltoreq. x.ltoreq.0.1.

14. The phosphor particle according to any one of claims 1 to 13, wherein an emission peak wavelength is 590nm or more.

15. The phosphor particle according to any one of claims 1 to 14, wherein the slit is a mark obtained by removing a hetero-phase.

16. A composite body is provided with:

the phosphor particles according to any one of claims 1 to 15, and a sealing material for sealing the phosphor particles.

17. A light-emitting device is provided with:

a light emitting element emitting excitation light, and

the composite according to claim 16, wherein the wavelength of the excitation light is made longer.

18. A method for producing the phosphor particles according to any one of claims 1 to 15, comprising the steps of:

a mixing step of mixing raw materials containing elements constituting Eu-containing alpha-sialon phosphor particles,

a heating step of heating the mixture of the raw materials to obtain an alpha-sialon phosphor,

a pulverization step of pulverizing the α -sialon phosphor obtained in the heating step to obtain α -sialon phosphor particles, and

and a step of forming slits on the surfaces of the α -sialon phosphor particles by subjecting the α -sialon phosphor particles obtained in the pulverization step to an acid treatment.

Technical Field

The invention relates to a phosphor particle, a composite, a light-emitting device, and a method for producing a phosphor particle.

Background

As nitride and oxynitride phosphors, α -type sialon phosphors obtained by activating a specific rare earth element are known to have useful fluorescence characteristics, and are used in white LEDs and the like. In the α -sialon phosphor, the Si — N bond portion of the α -type silicon nitride crystal is substituted with Al — N bond and Al — O bond, and in order to maintain electrical neutrality, there is a structure in which specific elements (Ca, Li, Mg, and Y, or lanthanoid metal excluding La and Ce) intrude into and are solid-dissolved in the crystal lattice between the crystal lattices. The fluorescent property is exhibited by using a rare earth element as a luminescence center as a part of the element which enters into the solid solution. Among them, an α -sialon phosphor obtained by dissolving Ca in a solid solution and substituting Eu for a part thereof is excited relatively efficiently in a wide wavelength region from the ultraviolet region to the cyan region, and exhibits yellow to orange emission. As an attempt to further improve the fluorescence characteristics 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 classification (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2009-96882

Disclosure of Invention

The present inventors have conducted intensive studies to improve the fluorescence characteristics of an α -sialon phosphor, and as a result, have found that the fluorescence characteristics of an α -sialon phosphor change depending on the surface shape of the α -sialon phosphor particles. Further, it has been studied which surface shape is advantageous for the fluorescent properties of the α -sialon phosphor, and the present invention has been completed.

The present invention has been made in view of such circumstances. The present invention provides a technique for further improving the fluorescence characteristics of alpha-sialon phosphor particles.

According to the present invention, there is provided phosphor particles of α -sialon containing Eu, wherein at least one slit is formed on the surface of the α -sialon phosphor particles.

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

Further, according to the present invention, there is provided a light-emitting device including a light-emitting element that emits excitation light and the complex that makes the wavelength of the excitation light longer.

Further, according to the present invention, there is provided a method for producing phosphor particles, the method comprising: a mixing step of mixing raw materials containing elements constituting Eu-containing α -type sialon phosphor particles; a heating step of heating the mixture of the raw materials to obtain an α -sialon phosphor; a pulverization step of pulverizing the α -sialon phosphor obtained in the heating step to obtain α -sialon phosphor particles; and a step of forming slits on the surfaces of the α -sialon phosphor particles by subjecting the α -sialon phosphor particles obtained in the pulverization step to an acid treatment.

According to the present invention, the fluorescent characteristics of the α -sialon phosphor particles can be improved.

Drawings

Fig. 1 (a) is a schematic view of a slit provided on the surface of an α -type sialon phosphor particle. Fig. 1 (b) is a schematic view of the slit when the cross section is in a diagonal V-shape.

Fig. 2 is a view showing the maximum diameter of the α -sialon phosphor particle in a plan view.

Fig. 3 is a schematic view showing one form of the slit.

Fig. 4 is a schematic view showing another form of the slit.

Fig. 5 is a schematic cross-sectional view showing the structure of the light-emitting device according to the embodiment.

Fig. 6 is an SEM image of the α -type sialon phosphor particles of example 1.

Fig. 7 is an SEM image of a cross section of a slit formed by the α -type sialon phosphor particles of example 1.

Fig. 8 is an SEM image of the α -type sialon phosphor particles of example 2 and an SEM image of a cross section of the slit formed.

Fig. 9 is an SEM image of the α -sialon phosphor particles of the additional comparative example.

FIG. 10 is an SEM image of α -type sialon phosphor particles of an additional comparative example.

Detailed Description

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

The phosphor particles of the embodiment are composed of α -type sialon phosphor particles containing Eu as an activator. At least one slit is formed on the surface of the α -sialon phosphor particle.

Here, the slit is a groove-like recess formed on the surface of the α -sialon phosphor particle, and in a cross section perpendicular to the extending direction of the recess (hereinafter, simply referred to as "cross section", it means a cross section perpendicular to the extending direction of the slit which is the groove-like recess), the deeper the depth of the recess is, the narrower the width is, and the deepest portion of the recess stays inside the α -sialon phosphor particle.

According to the α -sialon phosphor particles of the present embodiment, the fluorescence characteristics can be improved while maintaining the excitation wavelength region and the fluorescence wavelength region of the conventional α -sialon phosphor particles. Therefore, as a result, the light emission characteristics of the light-emitting device using the α -sialon phosphor particles can be improved.

For this reason, the detailed mechanism is not yet clarified, but for example, the slit formed on the surface of the α -sialon phosphor particle may have a concave structure as a feature for removing a trace of a heterogeneous phase that does not contribute to fluorescence. In the α -sialon phosphor particles having such slits formed therein, it is estimated that the heterogeneous phase not contributing to the fluorescence is removed in a wide range on the surface of the α -sialon phosphor particles other than the slits. As a result, it is considered that the ratio of mother crystals of the phosphor contributing to fluorescence is increased on the surface of the α -sialon phosphor particles, and the fluorescence characteristics of the α -sialon phosphor particles are improved.

In addition, it is considered that the light incident into the slit is taken into the inside of the α -sialon phosphor particles and efficiently extracted, and as a result, the fluorescence characteristics of the α -sialon phosphor particles are improved.

(alpha-sialon phosphor particle)

The α -type sialon phosphor particles containing Eu are composed of an α -type sialon phosphor described below.

The alpha-sialon phosphor is represented by the general formula: (M1_x，M2_y，Eu_z)(Si_12－(m+n)Al_m+n)(O_nN_16－n) (wherein M1 is a 1-valent Li element, and M2 is 1 or more 2-valent elements selected from Mg, Ca and lanthanides (excluding La and Ce)).

The solid solution composition of the alpha-sialon phosphor is represented by x, y, z in the above general formula and m and N determined by the Si/Al ratio and O/N ratio accompanying them, and is 0. ltoreq. x < 2.0, 0. ltoreq. y < 2.0, 0. ltoreq. z < 0.5, 0. ltoreq. x + y, 0.3. ltoreq. x + y + z < 2.0, 0. ltoreq. m.ltoreq.4.0, and 0. ltoreq. n.ltoreq.3.0.

Particularly, when Ca is used as M2, the α -sialon phosphor is stabilized in a wide composition range. By substituting Eu, which is a light emission center, for a part of Ca, and exciting the Ca with light in a wide wavelength range from ultraviolet to cyan, a phosphor exhibiting visible light emission from yellow to orange can be obtained.

From the viewpoint of obtaining bulb color light in illumination applications, the α -type sialon phosphor preferably contains no Li as a solid solution composition or a small amount of Li. In the above general formula, it is preferable that 0. ltoreq. x.ltoreq.0.1. And/or the ratio of Li in the α -sialon phosphor particles is preferably 0 to 1 mass%.

In general, an α -type sialon phosphor cannot be strictly defined in a solid solution composition by composition analysis or the like because of a second crystal phase different from the α -type sialon phosphor and an amorphous phase inevitably present. The α -sialon phosphor is preferably an α -sialon single phase as a crystal phase, and aluminum nitride or a polytype thereof may be contained as another crystal phase.

In the α -type sialon phosphor particles, a plurality of equiaxed primary particles are sintered to form massive secondary particles. The primary particles in the present embodiment are the smallest particles that can exist alone and can be observed by an electron microscope or the like.

The lower limit of the average particle diameter of the α -sialon phosphor particles is preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more. The upper limit of the average particle diameter of the α -sialon phosphor particles is preferably 30 μm or less, and more preferably 20 μm or less. The average particle diameter of the α -sialon phosphor particles is the size of the secondary particles. By setting the average particle diameter of the α -sialon phosphor particles to 5 μm or more, the transparency of the composite described later can be further improved. On the other hand, by setting the average particle diameter of the α -sialon phosphor particles to 30 μm or less, the generation of chips can be suppressed when the composite is cut by a dicing cutter or the like.

Here, the average particle size of the α -sialon phosphor particles is defined as follows according to JIS R1629: 1997 median diameter (D) in volume-based cumulative fractions determined by laser diffraction scattering₅₀)。

The shape of the α -sialon phosphor particle is not particularly limited. Examples of the shape include a spherical body, a cubic body, a columnar body, and an amorphous body.

(slits formed on the surface of the alpha-sialon phosphor particles)

At least one slit is formed on the surface of the alpha-sialon phosphor particle. The presence or absence of slits on the surface of the α -sialon phosphor particles can be confirmed by, for example, a Scanning Electron Microscope (SEM). In addition, the sectional shape and size of the slit can be confirmed as follows: the α -sialon phosphor particles were cut so as to expose a cross section orthogonal or intersecting with the extending direction of the slit, and the obtained cross section was observed by SEM. The method for cutting the α -sialon phosphor particles is not particularly limited. For example, ion beam cross-sectional polishing (CP) processing by ion milling is given.

Fig. 1 (a) is a schematic view of a slit provided on the surface of an α -type sialon phosphor particle. As shown in fig. 1 (a), the slit 20 is a notch cut into the surface of the α -type sialon phosphor particle 10 or a groove-like recess provided on the surface of the α -type sialon phosphor particle.

The width W of the slit 20 is the opening width of the slit 20 in the direction perpendicular to the extending direction or the longitudinal direction of the slit 20 on the surface of the α -type sialon phosphor particle 10. The width W of the slit 20 is a width when the surface of the α -sialon phosphor particle 10 is viewed from a direction perpendicular to the surface. The width W of the slit 20 may vary from location to location within a particular slit 20. The lower limit of the width W in at least one cross section of the slit 20 formation region is preferably 50nm or more, more preferably 100nm or more, and still more preferably 150nm or more. The upper limit of the width W is preferably 500nm or less, more preferably 450nm or less, and still more preferably 400nm or less.

The lower limit of the width W of the slit 20 in at least one cross section of the region where the slit 20 is formed is set to the above range, whereby the fluorescence characteristics of the α -sialon phosphor particle 10 can be further improved.

In addition, by setting the upper limit of the width W of the slit 20 to the above range, the fluorescence characteristics of the α -sialon phosphor particle 10 can be further improved while maintaining the intensity of the α -sialon phosphor particle 10.

The depth D of the slit 20 is the length from the surface of the α -type sialon phosphor particle 10 to the bottom of the slit 20. That is, the length from the edge of the wall to the slit bottom is set to the depth D of the slit 20. In the case where the heights of the left and right walls are different in fig. 1 (a), that is, in the case where there is a difference in height in the surface portion, the length from the edge portion of the higher wall to the slit bottom is set as the depth D of the slit 20.

The depth D of the slits 20 may vary from location to location within a particular slit 20.

The lower limit of the depth D of the slit 20 is preferably 200nm or more, more preferably 250nm or more, and still more preferably 300nm or more in at least one cross section of the slit 20 formation region. On the other hand, the upper limit of the depth D of the slit 20 is preferably 1500nm or less, more preferably 1400nm or less, and further preferably 1300nm or less.

The lower limit of the depth D in at least one cross section of the region where the slit 20 is formed is set to the above range, whereby the fluorescence characteristics of the α -sialon phosphor particle 10 can be further improved.

Further, by setting the upper limit of the depth D of the slit 20 to the above range, the fluorescence characteristics of the α -sialon phosphor particle 10 can be further improved while maintaining the intensity of the α -sialon phosphor particle 10.

As shown in fig. 1 (a), the slit 20 preferably has a V-shaped cross section portion formed by 2 surfaces of the wall 22 and the wall 24 in a cross section perpendicular to the extending direction of the slit 20.

It is considered that the V-shaped cross section formed by the slits 20 is generated when the heterogeneous phase not contributing to the fluorescence is removed more highly from the surface of the α -sialon phosphor particle 10. Therefore, it is considered that the slit 20 has a V-shaped cross section, and the fluorescent characteristics of the α -sialon phosphor particle 10 can be further improved.

Fig. 1 (b) is a schematic view of the slit 20 when the cross section is in a diagonal V shape. As shown in fig. 1 (b), in the cross section of the slit 20, an angle θ formed between the wall 22 forming one side of the slit 20 and the surface 12 of the α -type sialon phosphor particle is an acute angle. The angle θ is preferably 80 degrees or less.

It is considered that by making the angle θ acute, in other words, by making the cross-sectional shape of the slit 20 an inclined V-shape, the light incident into the slit 20 is further taken into the inside of the α -sialon phosphor particle 10 and is efficiently extracted, and as a result, the fluorescence characteristics of the α -sialon phosphor particle 10 can be further improved.

As shown in fig. 1 (b), when the angle θ is an acute angle, the depth D of the slit 20 is defined as a distance from the intersection of the wall 22 forming the angle θ and the surface 12 of the α -type sialon phosphor particle 10 to the deepest portion of the slit 20.

(in the case of the slit of FIG. 1 (a), the length from the edge portion of the "higher wall" of the 2-sided walls to the slit bottom is defined as D, but it should be noted that D in the slit of FIG. 1 (b) is not so.)

A plurality of slits 20 may be formed on the surface of the specific α -type sialon phosphor particle 10. It is considered that the plurality of slits 20 formed on the surface of the α -type sialon phosphor particle 10 are generated when the heterogeneous phase not contributing to the fluorescence is removed from the surface of the α -type sialon phosphor particle 10 more highly. Therefore, it is considered that the fluorescent characteristics of the α -type sialon phosphor particles 10 having a plurality of slits 20 on the surface are further improved. Further, by providing a plurality of slits 20, the amount of light incident on the entire slits 20 is increased, whereby the amount of light taken into the slits 20 and taken out of the α -sialon phosphor particles 10 can be increased, and the fluorescence characteristics of the α -sialon phosphor particles 10 can be further improved.

In this case, the extending direction of the plurality of slits 20 is not limited. The directions of extension may be parallel to each other, or may be different from each other. The plurality of slits 20 may be separated from each other or may intersect each other. The plurality of slits 20 may extend radially about the branch point.

As shown in fig. 2, the maximum diameter of the α -sialon phosphor particle 10 in a plan view is P. When the total of the path lengths along the slits 20 is L, L > P is preferable. This further increases the amount of light that enters and is extracted from the slit 20, and thus the amount of light that is taken into and out of the α -sialon phosphor particle 10 in the slit 20 can be further increased. Further, the fluorescence characteristics of the α -sialon phosphor particles 10 can be further improved.

Fig. 3 is a schematic view of the case where the α -type sialon phosphor particle 10 is a columnar body. As shown in fig. 3, when the α -sialon phosphor particles 10 are columnar bodies, the slits 20 preferably extend from one end portion to the other end portion of the side surface of the columnar body in the axial direction of the columnar body. This increases the total path length of the slit 20, and increases the amount of light entering the slit 20 and being extracted, thereby increasing the amount of light that is taken into the α -sialon phosphor particles 10 in the slit 20. Further, the fluorescence characteristics of the α -sialon phosphor particles 10 can be further improved.

Fig. 4 is a schematic view showing another slit form. The α -type sialon phosphor particle 10 shown in fig. 4 has a plurality of slits extending radially about a branch point. According to this configuration, the total path length of the slit 20 is increased, and the amount of light entering the slit 20 and extracted is increased, whereby the amount of light taken into the slit 20 and extracted from the α -type sialon phosphor particles 10 can be increased. Further, the fluorescence characteristics of the α -sialon phosphor particles 10 can be further improved. The α -type sialon phosphor particle 10 may be composed of a plurality of crystal grains, and the slit 20 may be formed between adjacent crystal grains.

The fluorescent particles described above have improved fluorescent properties by having the slits 20 on the particle surface. The phosphor powder containing the phosphor particles (having slits) described above has the above-described operational effect, that is, the operational effect of improving the fluorescence characteristics.

(method for producing phosphor particles)

A method for producing α -sialon phosphor particles according to this embodiment will be described. In the α -type sialon phosphor particles, a part of the raw material powder mainly reacts during the synthesis to form a liquid phase, and each element moves through the liquid phase, whereby solid solution formation and particle growth proceed.

First, raw materials containing elements constituting the Eu-containing α -type sialon phosphor particles are mixed. In alpha-sialon phosphor particles synthesized using calcium nitride as a calcium raw material and having a low oxygen content, calcium is dissolved in a high concentration. Particularly, when the Ca solid solution concentration is high, a phosphor having an emission peak wavelength on a higher wavelength side (590nm or more, more specifically, 590nm to 610nm, and even more specifically, 592nm to 608nm) than the conventional composition using an oxide raw material can be obtained. Specifically, in the above general formula, 1.5 < x + y + z.ltoreq.2.0 is preferable. It is also possible to substitute a part of Ca for Li, Mg, Sr, Ba, Y and lanthanoid (excluding La and Ce) and perform fine adjustment of the emission spectrum.

Examples of the raw material powder other than the above include silicon nitride, aluminum nitride, and Eu compound. Examples of the Eu compound include europium oxide, a compound which becomes europium oxide after heating, and europium nitride. Europium nitride is preferred to 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, these particles become the starting point of particle growth, α -sialon phosphor particles having a large minor axis diameter can be obtained, and the particle shape can be controlled by changing the form of the α -sialon particles added.

The above-mentioned raw materials may be mixed by a dry mixing method or a method of removing the solvent after wet mixing in an inert solvent which does not substantially react with the components of the raw materials. Examples of the mixing device include a V-type mixer, a swing type mixer, a ball mill, and a vibration mill. The mixing of calcium nitride, which is unstable in the atmosphere, is preferably performed in a glove box in an inert atmosphere because hydrolysis and oxidation thereof affect the characteristics of the resultant product.

The mixed powder (hereinafter, simply referred to as a raw material powder) is filled in a container made of a material having low reactivity with the raw material and the synthesized phosphor, for example, a container made of boron nitride. Subsequently, the mixture was heated in a nitrogen atmosphere for a predetermined time. This gave an α -type sialon phosphor. The temperature of the heat treatment is preferably 1650 ℃ to 1950 ℃.

By setting the temperature of the heat treatment to 1650 ℃ or higher, the remaining amount of unreacted product can be suppressed, and primary particles can be sufficiently grown. Further, by setting the temperature of the heat treatment to 1950 ℃ or lower, significant sintering between particles can be suppressed.

From the viewpoint of suppressing sintering between particles during heating, it is preferable to increase the volume of the raw material powder filled in the container. Specifically, it is preferable that the bulk density is set to 0.6g/cm when the container is filled with the raw material powder³The following.

The heating time in the heating treatment is preferably 2 to 24 hours, as a time range in which troubles such as the presence of a large amount of unreacted materials, insufficient primary particle growth, or sintering between particles do not occur.

By the above steps, the alpha-sialon fluorescence having an ingot-like outer shape is generatedAnd (3) a body. The secondary particles of the secondary particles-adjusted D can be obtained by subjecting the ingot-shaped α -sialon phosphor to a pulverizing step using a pulverizer such as a pulverizer, mortar pulverizing, ball mill, vibration mill or jet mill, and a screen classifying step after the pulverizing step₅₀A powder of alpha-sialon phosphor particles having a particle diameter. Further, by performing the step of dispersing the particles in an aqueous solution to remove secondary particles having a small particle diameter and being less likely to settle, D of the secondary particles can be adjusted₅₀And (4) the particle size.

The α -sialon phosphor particles of the present embodiment can be produced by performing the above-described steps and then performing an acid treatment step.

In the acid treatment step, for example, α -sialon phosphor particles are immersed in an acidic aqueous solution. Examples of the acidic aqueous solution include an acidic aqueous solution containing 1 acid selected from hydrofluoric acid, nitric acid, hydrochloric acid, and the like, and a mixed acid aqueous solution obtained by mixing 2 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 concentration of the stock solution of the acidic aqueous solution is appropriately set according to the strength of the acid used, and is, for example, preferably 0.7% to 100%, more preferably 0.7% to 40%. The temperature at the time of the acid treatment is preferably 60 to 90 ℃ and the reaction time (immersion time) is preferably 15 to 80 minutes.

By stirring at a high speed, the acid treatment of the particle surface can be easily and sufficiently performed. The "high speed" here also depends on the stirring apparatus used, but when a laboratory-grade magnetic stirrer is used, the stirring speed is, for example, 400rpm or more, and practically 400 to 500 rpm. From the viewpoint of the general purpose of stirring in which a new acid is continuously supplied to the particle surface, a stirring speed of about 200rpm is sufficient, but by performing high-speed stirring at 400rpm or more, the particle surface can be easily and sufficiently treated by physical action in addition to chemical action.

The number, shape and length of the slits formed on the surface of the α -sialon phosphor particle can be controlled by optimally adjusting the stock solution concentration of the acidic aqueous solution used for the acid treatment, the temperature at the time of the acid treatment, the reaction time and the like. For example, referring to the abundant examples described later, by performing the acid treatment under conditions similar to the combination of the stock solution concentration of the acidic aqueous solution, the temperature at the time of the acid treatment, and the reaction time used in the examples, slits having a desired number, shape, and length can be formed on the surface of the α -sialon phosphor particles.

(Complex)

The composite of the embodiment includes the phosphor particles and a sealing material for sealing the phosphor particles. In the composite of the present embodiment, a plurality of the above phosphor particles are dispersed in the sealing material. As the sealing material, a known material such as resin, glass, or ceramic can be used. Examples of the resin used for the sealing material include transparent resins such as silicone resin, epoxy resin, and urethane resin.

Examples of the method for producing the composite include the following methods: the phosphor particles of the present embodiment are prepared by adding a powder composed of α -sialon phosphor particles to a liquid resin or a powdery glass or ceramic, uniformly mixing the mixture, and then curing or sintering the mixture by heat treatment.

(light-emitting device)

Fig. 5 is a schematic cross-sectional view showing the structure of the light-emitting device according to the embodiment. As shown in fig. 5, the light-emitting device 100 includes a light-emitting element 120, a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, a bonding wire 170, a bonding wire 172, and a composite 40.

The light emitting element 120 is mounted on a predetermined region of 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 improved. Instead of the heat sink 130, a package substrate may be used.

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 generates light having a wavelength of 300nm to 500nm corresponding to light from near ultraviolet to cyan can be used. One electrode (not shown) disposed on the upper surface side of the light-emitting element 120 is connected to the surface of the first lead frame 150 by 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 by a bonding wire 172 such as a gold wire.

The housing 140 is formed with a substantially funnel-shaped recess portion whose aperture gradually increases from the bottom surface upward. 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 functions as a reflection plate.

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

In the light-emitting device 100 of the present embodiment, as described above, by using α -type sialon phosphor particles having slits formed on the surface thereof as the phosphor particles 1, the fluorescence characteristics of the phosphor particles 1 and the composite 40 can be improved, and the light emission intensity of the light-emitting device 100 can be improved.

Fig. 5 shows a surface-mount type light emitting device. However, the light emitting device is not limited to the surface mount type. The light emitting device may be a cannon type, a COB (chip on board) type, or a CSP (chip scale package) type.

While the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above may be adopted.

Examples

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

(example 1)

As the composition of the raw material powder, 62.4 parts by mass of silicon nitride powder (manufactured by Utsu Kagaku K.K., E10 grade), 22.5 parts by mass of aluminum nitride powder (manufactured by Tokuyama K.K., 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 high purity chemical research institute K.K.) were mixed in a glove box, and the mixture was dry-blended, and passed through a nylon sieve having a mesh size of 250. mu.m, to obtain a raw material mixed powder. 120g of this raw material mixed powder was charged into a cylindrical boron nitride container (N-1 grade, available from electrochemical Co., Ltd.) with a lid having an internal volume of 0.4 liter.

The raw material mixed powder was subjected to a heat treatment at 1800 ℃ for 16 hours in a nitrogen atmosphere of atmospheric pressure using an electric furnace of a carbon heater together with a vessel. Since calcium nitride contained in the raw material mixed powder is easily hydrolyzed in the air, the boron nitride container filled with the raw material mixed powder is taken out from the glove box, and then immediately placed in an electric furnace, and vacuum evacuation is performed to prevent the reaction of calcium nitride.

The resultant was lightly crushed with a mortar, and the whole was passed through a sieve having a mesh size of 150 μm to obtain a phosphor powder. The phosphor powder was examined for the crystal phase by powder X-ray Diffraction (hereinafter, referred to as XRD measurement) using CuK α rays, and the crystal phase present was Ca — α sialon (Ca-containing α sialon) containing Eu element.

Subsequently, 50ml of 50% hydrofluoric acid and 50ml of 70% nitric acid were mixed to prepare a mixed stock solution. 300ml of distilled water was added to the mixed stock solution, and the concentration of the mixed stock solution was diluted to 25% to prepare 400ml of a mixed acid aqueous solution. 30g of the powder composed of the α -sialon phosphor particles was added to the mixed acid aqueous solution, and the mixed acid aqueous solution was immersed for 60 minutes while being stirred at a rotation speed of 450rpm by a magnetic stirrer while maintaining the temperature of 80 ℃. The acid-treated powder was thoroughly washed with distilled water and then filtered, and after drying, the powder was passed through a sieve having a mesh size of 45 μm to prepare a powder composed of α -sialon phosphor particles of example 1.

(example 2)

A powder composed of α -type sialon phosphor particles of example 2 was produced in the same manner as in example 1 except that 396ml of distilled water was added to a mixed stock solution obtained by mixing 3.2ml of 50% hydrofluoric acid and 0.8ml of 70% nitric acid instead of the mixed acid aqueous solution used in example 1 to prepare a mixed acid aqueous solution having a stock solution concentration of 1.0%, and the phosphor powder was immersed for 30 minutes while maintaining the temperature of the mixed acid aqueous solution at 80 ℃.

(example 3)

A powder composed of α -type sialon phosphor particles of example 3 was produced in the same manner as in example 1, except that 396ml of distilled water was added to a mixed stock solution obtained by mixing 1.2ml of 50% hydrofluoric acid and 2.8ml of 70% nitric acid instead of the mixed acid aqueous solution used in example 1 to prepare a mixed acid aqueous solution having a stock solution concentration of 1.0%, and the phosphor powder was immersed for 30 minutes while maintaining the temperature of the mixed acid aqueous solution at 80 ℃.

(example 4)

A powder composed of α -type sialon phosphor particles of example 4 was produced in the same manner as in example 1, except that 396ml of distilled water was added to a mixed stock solution obtained by mixing 2.0ml of 50% hydrofluoric acid and 2.0ml of 70% nitric acid instead of the mixed acid aqueous solution used in example 1 to prepare a mixed acid aqueous solution having a stock solution concentration of 1.0%, and the phosphor powder was immersed for 30 minutes while maintaining the temperature of the mixed acid aqueous solution at 80 ℃.

(example 5)

The powder of example 5, which was composed of α -type sialon phosphor particles, was produced in the same manner as in example 1, except that 300ml of distilled water was added to 100ml (stock solution) of 50% hydrofluoric acid to prepare a hydrofluoric acid aqueous solution having a stock solution concentration of 25%, and the phosphor powder was immersed for 30 minutes while maintaining the temperature of the aqueous acid solution at 80 ℃.

Comparative example 1

A powder composed of α -type sialon phosphor particles of comparative example 1 was prepared in the same manner as in example 1 except that 398ml of distilled water was added to a mixed stock solution obtained by mixing 1.0ml of 50% hydrofluoric acid and 1.0ml of 70% nitric acid to obtain a stock solution having a stock solution concentration of 0.5%, and that acid treatment was performed for 30 minutes while maintaining the temperature of the mixed acid aqueous solution at 80 ℃ and stirring the mixed acid aqueous solution at a rotation speed of 300rpm with a magnetic stirrer, instead of the mixed acid aqueous solution used in example 1.

In the method for producing the powder composed of α -sialon phosphor particles according to comparative example 1, the stock solution concentration of the mixed acid aqueous solution used for the acid treatment was set to a level conventionally practiced.

(evaluation of characteristics)

[ luminescence characteristics ]

The absorption rate, internal quantum efficiency and external quantum efficiency of each of the obtained powders comprising α -type sialon phosphor particles were measured by a spectrophotometer (MCPD-7000, manufactured by Otsuka electronics Co., Ltd.) and calculated by the following procedure.

The powders of the α -type sialon phosphor particles of the examples and comparative examples were filled so that the surface of the concave cuvette was smooth, and an integrating sphere was attached. Monochromatic light split from a light emitting source (Xe lamp) into 455nm wavelength is introduced into the integrating sphere using an optical fiber. The sample of the phosphor is irradiated with the monochromatic light as an excitation source, and the fluorescence spectrum of the sample is measured.

A standard reflection plate (Spectralon, manufactured by Labsphere) having a reflectance of 99% was attached to the sample portion, and the spectrum of excitation light having a wavelength of 455nm was measured. At this time, the number of excitation photons is calculated from the spectrum in the wavelength range of 450nm to 465nm (Qex).

A powder composed of alpha-sialon phosphor particles was attached to the sample portion, and the number of photons of excitation reflected light (Qref) and the number of photons of fluorescence (Qem) were calculated from the obtained spectral data. The number of photons of the excitation reflected light is calculated in the same wavelength range as the number of photons of the excitation light, and the number of photons of the fluorescence is calculated in the range of 465nm to 800 nm.

Absorption rate (Qex-Qref)/Qex × 100

Internal quantum efficiency (Qem/(Qex-Qref)) × 100

External quantum efficiency (Qem/Qex). times.100

When the standard sample NSG1301 sold by Sialon co, ltd was measured by the above-described measurement method, the external quantum efficiency was 55.6% and the internal quantum efficiency was 74.8%. The apparatus was calibrated using the sample as a standard.

Incidentally, the peak wavelengths of the emission spectra obtained by the above measurements (wavelength of irradiated light: 455nm) of the powders composed of α -type sialon phosphor particles of examples 1 to 5 were all 600nm (higher wavelength).

[ measurement of particle size ]

The particle size was measured by using a Microtrac MT3300EX II (Microtrac · Bel co., ltd.) and by adjusting the particle size according to JIS R1629: 1997 by laser diffraction scattering. 0.5g of alpha-sialon phosphor particles were put into 100cc of ion-exchanged water, and dispersed for 3 minutes by Ultrasonic Homogenizer US-150E (chip size. phi.20 mm, Amplified 100%, oscillation frequency 19.5KHz, Amplitude about 31 μm, manufactured by Nippon Seiko Co., Ltd.), followed by particle size measurement by MT3300EX II. Determining the median diameter D from the particle size distribution obtained₅₀。

[ confirmation of slits ]

The surfaces of the α -sialon phosphor particles were observed by a Scanning Electron Microscope (SEM). Fig. 6 (a) is an SEM image of the α -sialon phosphor particles of example 1. As shown in fig. 6 (a), in example 1, it was confirmed that a plurality of slits were formed on the surface of the α -sialon phosphor particle. The slits intersect with each other and extend radially around the intersection (branch point).

Fig. 8 (a) is an SEM image of the α -sialon phosphor particles of example 2. As shown in fig. 8 (a), in example 2, a slit 20 is formed from one surface of the particle to the other surface.

In examples 1 and 2, it was confirmed that there were α -type sialon phosphor particles having a total L of path lengths along a plurality of slits larger than the maximum diameter P in plan view.

In addition, it was also confirmed that slits were formed on the surfaces of the α -sialon phosphor particles of examples 3 to 5. In contrast, in comparative example 1, it was confirmed that no slit was present on the surface of the phosphor particle.

[ Cross-sectional observation of slit ]

The α -type sialon phosphor particles of example 1 were cut by an ion milling device so that a cross section intersecting the slit was formed. Specifically, the cutting process is performed along a straight line shown in fig. 6 (b). The cross-sectional view of the obtained 2 slits by SEM is shown in fig. 7 (a) and (b). In one cross section of the α -type sialon phosphor particle of example 1, the depth of the slit was 808nm, and the width of the slit (width when viewed from the direction perpendicular to the surface of the α -type sialon phosphor particle) was 433 nm. The cross-sectional shape of the slit is a slanted V-shape. In the other cross section, the slit had a V-shape with a slit depth of 936nm and a slit width of 267 nm.

Similarly, the α -type sialon phosphor particles of example 2 were cut by an ion milling apparatus so as to have a cross section intersecting the slit. Specifically, the cutting process is performed along a straight line shown in fig. 8 (b). The cross section obtained is shown in fig. 8 (c) by SEM observation. In one cross section of the α -sialon phosphor particle of example 2, a V-shaped slit having a slit depth of 309nm and a slit width of 85.6nm was observed.

In addition, slits having a V-shaped cross section were also observed in the α -sialon phosphor particles of examples 3 to 5.

[ Table 1]

As shown in Table 1, it was confirmed that the α -sialon phosphor particles of examples 1 to 5, each having slits formed on the surface thereof, had improved internal quantum efficiency and external quantum efficiency and improved fluorescence characteristics as compared with comparative example 1.

(comparative example added: example obtained by changing the acid treatment conditions in example 3)

Alpha-sialon phosphor particles were obtained in the same manner as in example 3, except that the stirring speed of the magnetic stirrer in the acid treatment was changed from 450rpm to 200rpm, which is a normal level.

The median diameter D50 of the phosphor particles obtained in this additional comparative example was 14.5 μm. The obtained phosphor particles were observed by SEM in various visual fields, but there were no phosphor particles having slits formed on the surface. For reference, SEM images of the obtained phosphor particles are shown in fig. 9 and 10.

The phosphor particles obtained had an internal quantum efficiency of 75.4% and an external quantum efficiency of 66.6%, which were inferior to those of example 3 (and other examples).

The present application claims priority based on japanese application No. 2019-069104, filed on 3/29/2019, the disclosure of which is incorporated herein in its entirety.

Description of the symbols

1 phosphor particle

10 alpha-sialon phosphor particle

20 slit

30 sealing Material

40 composite body

100 light emitting device

120 light emitting element

130 heat sink

140 casing

150 first lead frame

160 second lead frame

170 bonding wire

172 join line