JP2016180023A - Phosphor particle and method for producing the same and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sulfide-based phosphor particle having excellent moisture resistance.SOLUTION: A phosphor has a composition represented by formula (I) and has a center value of circularity of 0.8 or more. In formula (I): (SrMEu) GaS, Mis at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y satisfy 0.03≤x≤0.25, 0≤y<0.97 and x+y<1).SELECTED DRAWING: None

Description

  The present disclosure relates to phosphor particles, a manufacturing method thereof, and a light emitting device.

A sulfide phosphor that emits green light whose composition is represented by SrGa ₂ S ₄ : Eu easily reacts with water. Therefore, for example, when stored or used in the air, there is a concern that the phosphor may deteriorate due to reaction with water in the air and the like, resulting in deterioration of the phosphor, resulting in a decrease in emission intensity and generation of sulfur-based gas. was there.

  In relation to the above, for example, Patent Documents 1 and 2 disclose sulfide phosphors having a coating layer, which can suppress the release of sulfur-based gas under high temperature and high humidity. For example, Patent Document 3 discloses a CaS: Eu red phosphor whose moisture resistance is improved by substituting part of Ca with Ba.

JP2013-119581A JP 2013-213096 A International Publication No. 2013/021990

In the sulfide phosphors described in Patent Documents 1 and 2, formation of the coating layer tends to be complicated, and sufficient moisture resistance may not be achieved. Further, the sulfide phosphor described in Patent Document 3 sometimes fails to achieve sufficient moisture resistance.
Therefore, one embodiment according to the present disclosure aims to provide sulfide-based phosphor particles having excellent moisture resistance.

Specific means for solving the above problems are as follows.
A first aspect according to the present disclosure is a phosphor particle having a composition represented by the following formula (I) and having a central value of circularity of 0.8 or more.
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
In the formula, M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y < 0.97 and x + y <1.

  A 2nd aspect which concerns on this indication is a light-emitting device provided with the fluorescent substance containing the said fluorescent substance particle, and the light source which emits the light which has a light emission peak wavelength in the range of 380 nm-485 nm.

According to a third aspect of the present disclosure, there is provided a fluorescence having a composition represented by the following formula (I), comprising heating a raw material mixture containing strontium, europium and gallium in a hydrogen sulfide atmosphere at a temperature of 950 ° C. or higher. It is a manufacturing method of a body particle.
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
In the formula, M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y < 0.97 and x + y <1.

  According to an embodiment of the present disclosure, sulfide-based phosphor particles having excellent moisture resistance can be provided.

3 is a diagram illustrating an example of an SEM image of a phosphor according to Example 1. FIG. 6 is a diagram illustrating an example of an SEM image of a phosphor according to Example 2. FIG. It is a figure which shows an example of the SEM image of the fluorescent substance concerning the comparative example 1. It is a figure which shows an example of the SEM image of the fluorescent substance concerning the comparative example 2. It is a figure which shows an example of the number distribution of the circularity of the fluorescent substance concerning this embodiment. It is a figure which shows an example of the number distribution of the aspect-ratio of the fluorescent substance which concerns on this embodiment. It is a schematic sectional drawing which shows an example of the light-emitting device which concerns on this embodiment.

  Hereinafter, the phosphor particles, the manufacturing method thereof, and the light emitting device according to the present disclosure will be described based on the embodiments and examples. However, the embodiment described below exemplifies phosphor particles, a manufacturing method thereof, and a light emitting device for embodying the technical idea of the present invention, and the present invention is a phosphor particle, a manufacturing method thereof, and The light emitting device is not specified as follows.

  The relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like in this specification conform to JIS Z8110. Specifically, 380 nm to 410 nm is purple, 410 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellowish red, and 610 nm to 780 nm is red.

  In this specification, the numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Moreover, content of each component in a composition means the total amount of the said some substance which exists in a composition, unless there is particular notice, when the substance applicable to each component exists in a composition in multiple numbers.

[Phosphor particles]
The phosphor particles of the present embodiment are green-emitting sulfide phosphor particles having a composition represented by the following formula (I) and having a center value of circularity of 0.8 or more.
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
In the formula, M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y < 0.97 and x + y <1.

  The phosphor particles exhibit excellent moisture resistance when the central value of the circularity is 0.8 or more, and a decrease in emission intensity is suppressed even in a high temperature and high humidity environment. Moreover, since generation | occurrence | production of the sulfur type gas accompanying hydrolysis is suppressed, when comprising a light-emitting device, the outstanding long-term reliability can be achieved. This can be considered, for example, because the ratio of the surface area to the volume of phosphor particles having a circularity in a predetermined range is small.

  The phosphor particles have a center value of circularity of 0.8 or more, and preferably 0.84 or more. For the central value of the circularity of the phosphor particles, the number distribution of the circularity of the phosphor particles is measured using a dry particle image analyzer, and the cumulative number from the smaller circularity side becomes 50% of the total. It is obtained as a circularity value. Here, the circularity of each phosphor particle is defined as follows. When the phosphor particles are projected from a certain direction, the area of the projected image of the phosphor particles and the perimeter thereof are S and M, respectively, and the circumference of a perfect circle whose area is S that is the same as the area of the projected image. When the thickness is L, the L / M value is defined as the circularity of the phosphor particles.

X in the formula (I) is 0.03 or more and 0.25 or less, preferably 0.05 or more and 0.25 or less, and more preferably 0.07 or more and 0.17 or less. If x is less than 0.03, there is a possibility that sufficient luminous efficiency may not be obtained when the phosphor particles are excited by a blue light emitting element. On the other hand, if it exceeds 0.25, sufficient light emission intensity may not be obtained due to concentration quenching, for example.
y is 0 or more and less than 0.97, preferably 0 or more and 0.9 or less, and more preferably 0 or more and 0.8 or less. This is because the emission peak wavelength of the phosphor can be changed by changing y, but if the amount of y is too large, the emission intensity may decrease.

  The average particle diameter of the phosphor particles is not particularly limited, and may be appropriately selected according to the purpose. For example, the average particle diameter of the phosphor particles is preferably 3 μm or more, and more preferably 5 μm or more. The average particle diameter of the phosphor particles is preferably 30 μm or less, and more preferably 25 μm or less. When the average particle diameter of the phosphor particles is 3 μm or more, the moisture resistance is further improved and the emission intensity tends to be more excellent. Moreover, there exists a possibility that emitted light intensity may fall that an average particle diameter is less than 3 micrometers. Here, the average particle size is a numerical value called Fisher Sub Sieve Sizer's No. (FSSSN). The specific surface area is measured by the air permeation method, and the average value of the primary particle size is measured. Is what we asked for. The average particle diameter is measured using, for example, a Fischer sub-sieve sizer (manufactured by Fischer).

  The average particle diameter of the phosphor particles can also be evaluated by the volume average particle diameter. The volume average particle diameter of the phosphor particles is determined as a particle diameter value at which the volume accumulation from the small diameter side is 50% in the volume accumulation particle size distribution.

  In the phosphor particles, the ratio of the Fischer sub-sieve sizers number to the volume average particle diameter is preferably 0.70 or more, and more preferably 0.76 or more. When the ratio of the Fischer sub-sieve sizers number to the volume average particle diameter is 0.70 or more, for example, the ratio of the surface area per volume is reduced, and it is considered that the moisture resistance is further improved.

  The aspect ratio of the phosphor particles is not particularly limited and may be appropriately selected according to the purpose. The center value of the aspect ratio of the phosphor particles is preferably 0.7 or more, and more preferably 0.75 or more. When the center value of the aspect ratio is 0.7 or more, the moisture resistance tends to be excellent. The aspect ratio of the phosphor particles is the ratio of the minor axis to the major axis of the phosphor particles, and the median of the aspect ratio of the phosphor particles is the aspect ratio of the particles constituting the phosphor using a dry particle image analyzer. Is obtained as an aspect ratio value at which the cumulative number from the side with a smaller aspect ratio becomes 50% of the total. Here, the aspect ratio of the phosphor particles is defined as the ratio of the minor diameter to the major diameter of the phosphor particles.

  The phosphor particles of the present embodiment are green-emitting phosphors and can be used for white LED light sources, fluorescent display tubes (VFD), field emission displays (FED), electroluminescence (EL), and the like.

Method for Producing Phosphor Particles In the method for producing phosphor particles of this embodiment, a raw material mixture containing strontium (Sr), europium (Eu), and gallium (Ga) is heated at a temperature of 950 ° C. or higher in a hydrogen sulfide atmosphere. This is a method for producing phosphor particles having a composition represented by the following formula (I).
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
In the formula, M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y < 0.97 and x + y <1.

  By heating the raw material mixture having a predetermined composition in a hydrogen sulfide atmosphere at a temperature of 950 ° C. or higher, phosphor particles having a desired composition and excellent in moisture resistance can be efficiently produced. This can be considered because, for example, the unevenness of the surface of the phosphor particles to be generated is reduced by heating at a temperature of 950 ° C. or higher. Moreover, there exists a tendency for the circularity of a fluorescent substance particle to improve because the unevenness | corrugation of the surface of a fluorescent substance particle reduces.

  The heating temperature (maximum value) is 950 ° C. or higher, preferably 960 ° C. or higher. The upper limit of the heating temperature is, for example, less than the melting point of the phosphor particles that can change depending on the composition of the phosphor particles, preferably 1200 ° C. or less, more preferably 1100 ° C. or less. If the heating temperature is less than 950 ° C., sufficient moisture resistance may not be achieved. Moreover, when heated at a temperature exceeding the melting point, the phosphor particles may be decomposed.

The raw material mixture contains at least strontium, europium and gallium, and at least one selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), barium (Ba) and zinc (Zn) as necessary. It may further contain seed elements, sulfur elements and the like. The composition of the raw material mixture can be appropriately selected according to the composition of the intended phosphor particles.
Examples of the compound that can be used for the raw material mixture include oxides, carbonates, sulfides, and the like containing elements such as strontium, europium, and gallium.

  The atmosphere for heating the raw material mixture only needs to contain at least hydrogen sulfide, and may contain a gas other than hydrogen sulfide as necessary. Examples of gases other than hydrogen sulfide include inert gases such as nitrogen, carbon disulfide, and the like. The hydrogen sulfide concentration in the hydrogen sulfide atmosphere for heating the raw material mixture is not particularly limited, and is, for example, 90% by volume or more, and preferably 95% by volume or more.

  The pressure condition in particular when heating a raw material mixture is not restrict | limited, For example, it can be set to 0.1-0.0.3MPa. The pressure condition is preferably 0.1 MPa (normal pressure). This is because if the pressure in the apparatus for heating the raw material mixture is too high, for example, hydrogen sulfide leaks from the apparatus to the external environment, which is dangerous.

  The heating time of the raw material mixture is not particularly limited as long as desired phosphor particles are obtained. The heating time at the heating temperature (maximum value) is, for example, 1 to 20 hours, preferably 1 to 10 hours.

  In the method for producing phosphor particles, after the heat treatment of the raw material mixture, a dispersion treatment, a drying treatment, a classification treatment, or the like may be performed as necessary.

Light-emitting device The light-emitting device of this embodiment is equipped with the fluorescent substance containing the said fluorescent substance particle, and the light source which emits the light which has light emission peak wavelength in the range of 380 nm or more and 485 nm or less.
When the phosphor includes the phosphor particles, a light emitting device having excellent moisture resistance and high long-term reliability can be configured. For example, a light emitting element can be used as the light source.

The emission peak wavelength of the light-emitting element that serves as the light source is in the range of 380 nm to 485 nm, and preferably in the range of 400 nm to 470 nm. By using a light emitting element having an emission peak wavelength in this range as an excitation light source, it is possible to configure a light emitting device that emits mixed light of light from the light emitting element and fluorescence from the phosphor. Furthermore, since light emitted from the light emitting element to the outside can be used effectively, loss of light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be obtained.
The half width of the emission spectrum of the light emitting element is not particularly limited. The half width can be set to 30 nm or less, for example.

A semiconductor light emitting element is preferably used as the light emitting element. By using a semiconductor light emitting element as a light source, it is possible to obtain a stable light emitting device with high efficiency, high output linearity with respect to input, and strong against mechanical shock.
As a semiconductor light emitting element, for example, a blue color using a nitride semiconductor (In _a Al _b Ga _1-ab N, where a and b satisfy 0 ≦ a, 0 ≦ b, and a + b ≦ 1) is used. A semiconductor light emitting element that emits green light or the like can be used.

  It is preferable that the phosphor further includes another phosphor in addition to the phosphor particles. As the other phosphor, a phosphor that emits red light by the light of the light emitting element can be preferably exemplified. Specifically, the fluorescence which light-emits red light the nitride fluorescent substance which has a composition represented by following formula (II) or (III), and the fluoride fluorescent substance which has a composition represented by following formula (IV). It can be further included as a body. In particular, when a light-emitting device combined with a fluoride phosphor having a composition represented by the following formula (IV) is configured, the range of color reproducibility is wider than in the conventional case when used as a backlight light source for an image display device. This is preferable.

_{(Ca 1-p-q Sr} p Eu q) AlSiN 3 (II)
In formula (II), p and q satisfy 0 ≦ p ≦ 1.0, 0 <q <1.0 and p + q <1.0.
_{(Ca 1-r-s-} t Sr r Ba s Eu t) 2 Si 5 N 8 (III)
In the formula (III), r, s, and t satisfy 0 ≦ r ≦ 1.0, 0 ≦ s ≦ 1.0, 0 <t <1.0, and r + s + t ≦ 1.0.
^{_{A 2 [M 2 1-u}} Mn 4+ u F 6] (IV)
In the formula (IV), A is at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M ² is a Group 4 element And at least one element selected from the group consisting of Group 14 elements, and u satisfies 0 <u <0.2.

The light emitting device can include, for example, a phosphor and a sealing resin, and can include a sealing member that seals the light emitting element. Examples of the sealing resin constituting the sealing member include thermoplastic resins and thermosetting resins. Specific examples of the thermosetting resin include modified silicone resins such as epoxy resins, silicone resins, and epoxy-modified silicone resins.
The composition of the phosphor in the sealing member and the content ratio with respect to the sealing resin can be appropriately selected according to the purpose and the like.

  The sealing member may contain other components as needed in addition to the phosphor and the sealing resin. Examples of other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, light stabilizers, and colorants. When a sealing member contains another component, the content in particular is not restrict | limited, According to the objective etc., it can select suitably. For example, when a filler is included as another component, the content thereof can be 0.01 to 20 parts by mass with respect to 100 parts by mass of the sealing resin.

  The form of the light emitting device is not particularly limited, and can be appropriately selected from commonly used forms. As a type of the light emitting device, a shell type, a surface mount type, and the like can be given. In general, the bullet shape refers to a shape in which the shape of the resin constituting the outer surface is formed into a bullet shape. In addition, the surface mount type refers to the one formed by filling a light emitting element serving as a light source and a resin in a concave storage portion. Furthermore, as a form of the light emitting device, a light emitting device in which a light emitting element serving as a light source is mounted on a flat mounting substrate, and a sealing resin containing a phosphor is formed in a lens shape so as to cover the light emitting element, etc. Also mentioned.

An example of the light emitting device according to the present embodiment will be described with reference to the drawings. FIG. 7 is a schematic cross-sectional view showing an example of a light emitting device according to this embodiment. This light-emitting device is an example of a surface-mounted light-emitting device.
The light emitting device 100 emits light on the short wavelength side of visible light, and includes a light emitting element 10 of a gallium nitride compound semiconductor having an emission peak wavelength of 380 nm to 485 nm, and a molded body 40 on which the light emitting element 10 is mounted. Have. The molded body 40 has a first lead 20 and a second lead 30 and is integrally molded with a sealing resin that is a thermoplastic resin or a thermosetting resin. The molded body 40 has a recess having a bottom surface and side surfaces, and the light emitting element 10 is placed on the bottom surface of the recess. The light emitting element 10 has a pair of positive and negative electrodes, and the pair of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30 through wires 60, respectively. The light emitting element 10 is sealed with a sealing member 50. The sealing member 50 is preferably made of a thermosetting resin such as an epoxy resin, a silicone resin, an epoxy-modified silicone resin, or a modified silicone resin. The sealing member 50 contains a green phosphor (first phosphor 71) and a red phosphor (second phosphor 72) that convert the wavelength of light from the light emitting element 10 and a sealing resin. The first phosphor 71 is a phosphor particle having a composition represented by the formula (I) according to the present embodiment, the center value of circularity is 0.8 or more, and the second phosphor is A nitride phosphor having a composition represented by formula (II) or (III) or a fluoride phosphor having a composition represented by formula (IV).

  The sealing member 50 is formed by being filled with a translucent resin or glass so as to cover the light emitting element 10 placed in the recess of the light emitting device 100. In view of ease of production, the material of the sealing member is preferably a translucent resin. Although it is preferable to use a silicone resin composition for the translucent resin, an insulating resin composition such as an epoxy resin composition or an acrylic resin composition can also be used. The sealing member 50 contains the first phosphor 71 and the second phosphor 72, but other materials can be added as appropriate. For example, by including a light diffusing material, the directivity from the light emitting element can be relaxed and the viewing angle can be increased.

  The sealing member 50 functions not only as a member for protecting the light emitting element 10, the first phosphor 71 and the second phosphor 72 from the external environment, but also as a wavelength conversion member. In FIG. 1, the first phosphor 71 and the second phosphor 72 are partially unevenly distributed in the sealing member 50. Thus, by arranging the first phosphor 71 and the second phosphor 72 close to the light emitting element 10, the wavelength of light from the light emitting element 10 can be efficiently converted, and the light emission efficiency is excellent. It can be a light emitting device. In addition, arrangement | positioning with the sealing member 50 containing the 1st fluorescent substance 71 and the 2nd fluorescent substance 72, and the light emitting element 10 is not limited to the form which arrange | positions them closely, 1st fluorescence Considering the influence of heat on the body 71 and the second phosphor 72, the light emitting element 10 and the first phosphor 71 and the second phosphor 72 are spaced apart in the sealing member 50. You can also Further, by mixing the first phosphor 71 and the second phosphor 72 with the entire sealing member 50 at a substantially uniform ratio, it is possible to obtain light in which color unevenness is further suppressed.

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

Example 1
SrCO ₃ manufactured by Sakai Chemical, Eu ₂ O ₃ manufactured by Shin-Etsu Chemical, and Ga ₂ O ₃ manufactured by New Materials are weighed so that Sr, Eu and Ga have a molar ratio of Sr _0.88 Eu _0.12 Ga ₂ S _4. And mixed until sufficiently uniform.
The obtained raw material mixture was filled in a quartz crucible and heated at 960 ° C. for 2 hours in a hydrogen sulfide (H ₂ S) atmosphere to produce phosphor particles.
About the obtained phosphor particles, media (PE <Mirason> manufactured by Mitsui / DuPont Polychemical): phosphor particles: pure water = 2: 1: 2 is mixed, and a water glass-based dispersant is further added to the phosphor particles. The mixture obtained by adding 0.1% by weight with respect to the weight was subjected to wet dispersion for 15 hours. Next, the phosphor particles were separated, dried, and passed through a nylon mesh (N-No. 305T, opening of 48 μm) to obtain the phosphor particles of Example 1.
FIG. 1 shows a scanning electron microscope (SEM) image (5,000 times) of the phosphor particles obtained in Example 1.

(Example 2)
Weigh SrS manufactured by Wako Pure Chemical Industries, EuS manufactured by Mitsuba Chemical Co., Ltd. and Ga ₂ S ₃ manufactured by Wako Pure Chemical Industries, so that Sr, Eu and Ga have a molar ratio of Sr _0.88 Eu _0.12 Ga ₂ S ₄ , Mix until fully uniform. The obtained raw material mixture was filled in a quartz crucible and heated at 960 ° C. for 2 hours in a hydrogen sulfide (H ₂ S) atmosphere to produce phosphor particles. Thereafter, the same treatment as in Example 1 was carried out to obtain Example 2 phosphor particles.
FIG. 2 shows an SEM image (5000 times) of the phosphor particles obtained in Example 2.

(Comparative Example 1)
In Example 1, phosphor particles of Comparative Example 1 were obtained in the same manner as in Example 1 except that the heating temperature was 850 ° C.
FIG. 3 shows an SEM image (5000 times) of the phosphor particles obtained in Comparative Example 1.

(Comparative Example 2)
In Example 1, phosphor particles of Comparative Example 2 were obtained in the same manner as in Example 1 except that the heating temperature was 900 ° C.
FIG. 4 shows an SEM image (5000 times) of the phosphor particles obtained in Comparative Example 2.

[Evaluation]
The following evaluation was performed on the phosphor particles obtained above.
(Roundness evaluation)
Using a dry particle image analyzer (Morphology G3SE: Malvern), the circularity of about 40000 phosphor particles is measured, and the circularity at which the cumulative number of particles from the low circularity side becomes 50% is obtained. Evaluation was made as the center value of the circularity of the particles.
FIG. 5 shows the number distribution of the circularity measured by the dry particle image analyzer.

(Aspect ratio evaluation)
The aspect ratio was measured instead of the circularity, and the center value of the aspect ratio of the phosphor particles was evaluated in the same manner as the circularity evaluation.
FIG. 6 shows the number distribution of aspect ratios measured by a dry particle image analyzer.

(Average particle diameter: F.S.S.S.N.)
About the fluorescent substance particle obtained above, the average particle diameter was measured as a Fischer sub-sieve sizer number using a Fischer sub-sieve sizer (made by Fischer).

(Volume average particle diameter: Dm)
The phosphor particles obtained above were subjected to a dispersion treatment for 60 seconds by ultrasonic irradiation, and then a volume average particle diameter Dm using a particle size distribution analyzer Multisizer (product name) (manufactured by Beckman Coulter, Inc.). And σ _log , which is a distribution from Dm, was measured.

(Phosphor chromaticity coordinates)
The phosphor particles obtained above were measured for chromaticity coordinates (x, y) when excited with a light emitting device having an emission peak wavelength of 460 nm.

(LED reliability evaluation)
Using a LED chip (light-emitting element) having an emission peak wavelength of 455 nm, a surface-mounted light-emitting device was prototyped in combination with a phosphor. The phosphor particles obtained above and CaAlSiN _3, which is a phosphor having an emission peak wavelength at 650 nm, so that the chromaticity coordinates of the mixed light emitted from the light emitting device are in the vicinity of x = 0.272 and y = 0.247. : Eu was blended, added to the silicone resin, mixed and dispersed to obtain a phosphor-containing resin composition. Next, the phosphor-containing resin composition was injected and filled onto the light emitting element, and then the resin was cured to produce a light emitting device.
The obtained light-emitting device is continuously lit at a current of 150 mA in a high-temperature and high-humidity environment tester at 60 ° C. and a relative humidity of 90%, and the difference from the initial value of the y value in the chromaticity coordinates after 1000 hours is determined as the LED reliability. It was evaluated as Δy. The evaluation results are shown in Table 1.

As shown in Table 1, the light emitting device using the phosphor particles according to Examples 1 and 2 having a central value of the circularity of 0.8 or more is light emission using the phosphor particles of Comparative Examples 1 and 2. The amount of change (Δy) in the y value in the LED reliability test is smaller than that of the device. That is, it can be seen that the light emitting devices using the phosphor particles of Examples 1 and 2 have little deterioration of the phosphor and high reliability. This is thought to be because the circularity of the phosphor particles is increased, that is, the surface area of the phosphor is reduced, so that the surface area in contact with the outside air containing moisture is reduced and the deterioration of the phosphor is suppressed. .
Also, as shown in FIGS. 1 and 2, the phosphor particles of Examples 1 and 2 are generally particles as compared with the phosphor particles of Comparative Examples 1 and 2 shown in FIGS. It can be seen that the size increases and the number of particles having large irregularities on the particle surface decreases.

  In the present embodiment, the green phosphor particles can be combined with an excitation light source to constitute a green light emitting element, and can be used for various applications. For example, in addition to general illumination, it can be used for special light sources, liquid crystal backlights, display devices such as EL, FED, and CRT display devices.

  10: light emitting element, 50: sealing member, 71: first phosphor, 72: second phosphor, 100: light emitting device

Claims (6)

Having a composition represented by the following formula (I):
A phosphor particle having a central value of circularity of 0.8 or more.
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
(Wherein M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y. <0.97 and x + y <1.)   The phosphor particles according to claim 1, wherein the phosphor particles have an average particle size of 3 μm or more. A phosphor containing the phosphor particles according to claim 1, and
A light source that emits light having an emission peak wavelength in the range of 380 nm to 485 nm;
A light emitting device comprising: The light-emitting device according to claim 3, wherein the phosphor further includes a nitride phosphor having a composition represented by the following formula (II) or (III).
_{(Ca 1-p-q Sr} p Eu q) AlSiN 3 (II)
(In the formula (II), p and q satisfy 0 ≦ p ≦ 1.0, 0 <q <1.0 and p + q <1.0.)
_{(Ca 1-r-s-} t Sr r Ba s Eu t) 2 Si 5 N 8 (III)
(In the formula (III), r, s, and t satisfy 0 ≦ r ≦ 1.0, 0 ≦ s ≦ 1.0, 0 <t <1.0, and r + s + t ≦ 1.0.) The light-emitting device according to claim 3, wherein the phosphor further includes a fluoride phosphor having a composition represented by the following formula (IV).
^{_{A 2 [M 2 1-u}} Mn 4+ u F 6] (IV)
(In the formula (IV), A is at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M ² is Group 4 (At least one element selected from the group consisting of elements and Group 14 elements, and u satisfies 0 <u <0.2.) A phosphor having a composition represented by the following formula (I), comprising heating a raw material mixture containing strontium (Sr), europium (Eu), and gallium (Ga) at a temperature of 950 ° C. or higher in a hydrogen sulfide atmosphere. Particle production method.
(Sr _1-xy M ¹ _y Eu _x ) Ga ₂ S ₄ (I)
(Wherein M ¹ represents at least one element selected from the group consisting of Be, Mg, Ca, Ba and Zn, and x and y are 0.03 ≦ x ≦ 0.25, 0 ≦ y. <0.97 and x + y <1.)