WO2017155111A1

WO2017155111A1 - Phosphor, light-emitting element, and light-emitting device

Info

Publication number: WO2017155111A1
Application number: PCT/JP2017/009792
Authority: WO
Inventors: 紗緒梨井之上; 智宏野見山
Original assignee: デンカ株式会社
Priority date: 2016-03-11
Filing date: 2017-03-10
Publication date: 2017-09-14
Also published as: TWI751140B; TW201802230A; JP6970658B2; KR102399783B1; JPWO2017155111A1; KR20180118223A; CN108779394A

Abstract

Provided is a light-emitting device having high fluorescence intensity and minimal decrease in light-emitting efficiency even when used for a long time, and a phosphor for the same. The present invention is: an Eu-activated Li-α-sialon-based phosphor, the F content of the phosphor being 20 mass ppm or less, the total content of P and Na being 10 mass ppm or less, and the ratio of α-sialon crystals with respect to the entire crystal phase being 95 mass% or greater; and a light-emitting device provided with the phosphor.

Description

Phosphor, light emitting element and light emitting device

The present invention relates to a phosphor. The present invention also relates to a light emitting element including a phosphor. Furthermore, the present invention relates to a light emitting device including a light emitting element.

Conventionally, as a phosphor emitting orange light, the general _{_{_{formula: Ca x Eu y Si 12- (}}} m + n) Al (m + n) is represented by O _{_n} N _{_16-n,} to stabilize the crystal structure Ca-α sialon phosphors using Ca ²⁺ as the metal ion are known, and high luminous efficiency is obtained (see Patent Document 1). In the light emitting device including the α sialon phosphor using Ca ²⁺ , there is no problem that the light emission efficiency of the light emitting device is lowered when used for a long time.

On the other hand, in recent years, improvement in luminance and shortening of the fluorescence spectrum have been studied, and Li-α sialon phosphors using Li ⁺ as metal ions for stabilizing the crystal structure have been proposed (Patent Documents 2 to 4). 4). As a result, the luminance of the light emitting device was improved and the wavelength was shortened by providing the Li-α sialon phosphor compared with the light emitting device using the Ca-α sialon phosphor. There has been a new problem that the luminous efficiency of the light emitting device is lowered due to deterioration of the resin that is the sealing material of the LED package, which is considered to be caused by ionization of the impurity element contained in the phosphor (see Patent Document 5). .

On the other hand, in Patent Documents 6 to 7, a CASN phosphor, which is an oxynitride phosphor similar to α-sialon, which is a kind of red-emitting phosphor, has a halogen element that is not an element constituting a crystal phase. It is also known that elements other than the elements constituting the crystal phase do not necessarily have an adverse effect, as reported in that high luminous efficiency can be obtained.

JP 2002-363554 A International Publication No. 2007/004493 International Publication No. 2010/018873 JP 2010-202738 A JP 2009-224754 A JP 2010-188771 A Special table 2012-512307 gazette

Thus, although various studies have been made to improve the characteristics of the Li-α sialon-based phosphor, there is still room for improvement with respect to a decrease in luminous efficiency due to long-term use. An object of the present invention is to provide a light emitting device having high fluorescence intensity and little reduction in luminous efficiency even when used for a long time, and a phosphor therefor.

One aspect of the present invention is an Eu-activated Li-α sialon-based phosphor having an F content of 20 ppm by mass or less and a total content of P and Na of 10 ppm by mass or less. The phosphor is such that the ratio of α-sialon crystals to the phase is 95% by mass or more.

In one embodiment of the phosphor according to the present invention, the total content of P and Na is 5 mass ppm or less.

In another embodiment of the phosphor according to the present invention, the Li content is 1.8% by mass or more and 3% by mass or less.

In yet another embodiment of the phosphor according to the present invention, the Eu content is 0.1% by mass or more and 1.5% by mass or less.

In yet another embodiment of the phosphor according to the present invention, the O content is 0.4 mass% or more and 1.3 mass% or less.

In yet another embodiment of the phosphor according to the present invention, the average primary particle size is 7 μm or more and 35 μm or less.

In another aspect, the present invention is a light emitting element including the phosphor according to the present invention and a light emitting light source that irradiates the phosphor with excitation light.

In one embodiment of the light emitting device according to the present invention, the light emitting light source is a light emitting diode or a laser diode.

In another embodiment of the light emitting device according to the present invention, the luminous flux retention is 95% or more when left at a current of 150 mA for 1000 hours under conditions of a temperature of 85 ° C. and a relative humidity of 85%.

In yet another aspect, the present invention is a light emitting device including the light emitting element according to the present invention.

In the present invention, in the Eu-activated Li-α sialon phosphor, the content of F, Na, and P was reduced while increasing the proportion of α sialon crystals relative to the total crystal phase. By using the phosphor according to the present invention, a high fluorescence intensity can be obtained, and a light emitting device with little decrease in luminous efficiency can be obtained even when used for a long time.

In one aspect, the present invention relates to an Eu-activated Li-α sialon-based phosphor. Eu-activated Li-α sialon-based phosphors are generally represented by the following formula: Li _x Eu _y Si _{12- (m + n)} Al _{m +} _{n On} N _16-n (x + y ≦ 2, m = x + 2y) A phosphor having a compound. In this phosphor, Li and Eu penetrate into the voids in the crystal so that part of the Si-N bond of the α-silicon nitride crystal is replaced by Al-N bond and Al-O bond, and electrical neutrality is maintained. The m value and the n value correspond to the substitution rate to the Al—N bond and Al—O bond, respectively.

The reason why Li ⁺ is used in the present invention is not for the purpose of shortening the conventional wavelength, but to obtain a higher fluorescence intensity than that of Ca ²⁺ . The solid solution composition range of α-sialon is limited not only by the number of solid solution sites of the stabilizing cation, but also by thermodynamic stability according to the stabilizing cation. In the case of Li ⁺ , the range of m value that can maintain the α-sialon structure is 0.5 or more and 2 or less, and the range of n value is 0 or more and 0.5 or less. If the Li content in the phosphor of the present invention is too small, the progress of grain growth in the phosphor firing step tends to be very slow, and it is difficult to obtain large particles with high fluorescence intensity. If it is too large, LiSi ₂ N ₃ It is preferable that it is 1.8 mass% or more and 3 mass% or less since it exists in the tendency to produce | generate another phase, such as. Li content can be adjusted with the raw material mixing | blending of fluorescent substance. Specifically, it adjusts by the increase / decrease of the compounding ratio of lithium nitride or lithium oxide as a Li containing raw material.

If the Eu content in the phosphor of the present invention is too small, the contribution to light emission tends to be small and the fluorescence intensity tends to be low. If too large, the fluorescence intensity due to fluorescence concentration quenching due to energy transfer between Eu ²⁺ is low. Since it tends to be low, it is preferably 0.1% by mass or more and 1.5% by mass or less. Eu content can be adjusted with the raw material mixing | blending of fluorescent substance. Specifically, it is adjusted by increasing or decreasing the compounding ratio of the europium oxide and europium nitride of the Eu-containing raw material.

The oxygen (O) content in the phosphor of the present invention is preferably 0.4% by mass or more and 1.3% by mass or less. This is because a phosphor with too little oxygen content has little crystal grain growth in the manufacturing process and high fluorescence intensity cannot be obtained. If the oxygen content is too much, the fluorescence spectrum becomes broad and sufficient. This is because the fluorescence intensity cannot be obtained.

In order to obtain a phosphor with little decrease in luminous efficiency even when used for a long time, among the impurity elements of the phosphor, the content of F is preferably 20 mass ppm or less, and 10 mass ppm or less. More preferably, it is more preferably 5 ppm by mass or less, for example, 1 to 20 ppm by mass. As will be described later, it is effective to acid-treat the phosphor in order to increase the ratio of α-sialon crystals in the phosphor and improve the light emission characteristics, but F is an element that is easily mixed during acid treatment. It is difficult to sufficiently improve the light emission characteristics by only the acid treatment, and it is important to remove F after the acid treatment in order to obtain excellent luminescence efficiency.

Further, it is desirable to further control the total content of P and Na in order to suppress a decrease in light emission efficiency of a light emitting device including a phosphor and reduce the occurrence of electrical failure even when used for a long time. . Specifically, the total content of P and Na is preferably 10 mass ppm or less, more preferably 5 mass ppm or less, still more preferably 2 mass ppm or less, for example, 1 to 5 ppm. The mass can be ppm. As will be described later, in order to improve the light emission characteristics by increasing the proportion of the α sialon crystal of the phosphor, it is effective to remove the phosphor fine powder by classification. For the classification, wet classification using sodium hexametaphosphate as a dispersant can be adopted, but in this method, P and Na are likely to be mixed. Therefore, in this case, it is difficult to improve the light emission characteristics sufficiently only by classification, and it is important to remove Na and P after classification to obtain excellent emission efficiency. In order to reduce the burden of the washing process after the classification process by further controlling the P content and the Na content, the classification process may employ wet classification using an alkaline solvent, or may be dry classification. .

The phosphor of the present invention is selected from the group consisting of Mg, Ca, Y and lanthanide elements (excluding La, Ce, Eu) for the purpose of fine-tuning the fluorescence characteristics. Substitution may be performed while maintaining electrical neutrality with one or more substitution elements. Therefore, in one embodiment of the Eu-activated Li-α sialon-based phosphor, Li is partially substituted by one or more of such substitution elements.

As long as the phosphor of the present invention does not affect the fluorescence properties, the crystal phase present in the phosphor is not limited to α sialon single phase, but also a crystal phase such as silicon nitride, aluminum nitride, lithium silicon nitride and solid solutions thereof. It can also be included. However, in general, the proportion of α sialon in the phosphor is preferably 95% by mass or more, more preferably 97% by mass or more, still more preferably 98% by mass or more, for example, 95 to 99% by mass. it can.

If the average primary particle size in the phosphor of the present invention is too small, the fluorescence intensity tends to be low, and if it is too large, the chromaticity of the emitted color when the phosphor is mounted on the light emitting surface of the LED may vary or emit light. Since uneven color tends to occur, it is preferably 7 μm or more and 35 μm or less. The average primary particle diameter here refers to a volume-based median diameter (D50) determined by a laser diffraction / scattering method.

The phosphor according to the present invention can be manufactured through a raw material mixing step, a firing step, an acid treatment step, and a washing step. After the acid treatment step, the classification step is preferably performed before, after, or both before and after the washing step, and more preferably, the classification step is performed both before and after the washing step.

First, phosphor raw materials other than lithium nitride powder such as silicon nitride powder, aluminum nitride powder, and europium oxide are mixed at a desired ratio. In consideration of industrial productivity, mixing is preferably performed by wet mixing. After the wet mixing, a premixed powder is obtained through solvent removal, drying and crushing. The premixed powder is mixed with the lithium nitride powder at a desired ratio to obtain a raw material mixed powder. Mixing is preferably performed in a nitrogen atmosphere or the like in order to suppress hydrolysis.

It is possible to obtain Eu-activated Li-α sialon by firing the raw material mixed powder. The crucible used for firing is preferably made of a material that is stable in a high-temperature atmosphere, and is preferably made of boron nitride, carbon, or a refractory metal such as molybdenum or tantalum. The firing atmosphere is not particularly limited, but is usually performed in an inert gas atmosphere or a reducing atmosphere. Only one type of inert gas or reducing gas may be used, or two or more types may be used in any combination and ratio. Examples of the inert gas or reducing gas include hydrogen, nitrogen, argon, ammonia, and the like. Among these, a nitrogen atmosphere is preferable. The pressure of the firing atmosphere is selected according to the firing temperature. The higher the atmospheric pressure is, the higher the decomposition temperature of the phosphor is. However, in consideration of industrial productivity, it is preferable to carry out under a pressure of about 0.02 to 1.0 MPa. When the firing temperature is lower than 1650 ° C., the number of crystal defects and unreacted residual amount of the base crystal increases, and when the temperature exceeds 1900 ° C., the base is decomposed. Therefore, the firing temperature is preferably 1650 to 1900 ° C. If the firing time is short, there are many crystal defects and unreacted residual amount of the base crystal, and if the firing time is long, it is not preferable in view of industrial productivity. Therefore, it is preferably 2 to 24 hours. The obtained Eu-activated Li-α sialon may be classified to a desired particle size as necessary.

Since Eu-activated Li-α sialon obtained by calcination generally has a low α sialon crystal ratio, it is difficult to exhibit excellent fluorescence intensity. For this reason, it is preferable to increase the crystal ratio of α-sialon by acid treatment with a mixed solution of hydrofluoric acid and nitric acid.

As described above, since the fluorescent intensity tends to decrease when the particle size of the phosphor is too small, a classification step for removing fine powder after the acid treatment step may be performed in order to obtain a high-luminance phosphor. preferable. The classification step may be either wet or dry, but the phosphor is mixed in a mixed solvent of ion-exchanged water and sodium hexametaphosphate as a dispersant or in a mixed basic solvent of ion-exchanged water and ammonia water. The elutriation classification or the dry classification is preferable.

By passing through the acid treatment and classification step, the crystal ratio of α sialon can be increased. However, when acid treatment with a mixed solution of hydrofluoric acid and nitric acid or water tank classification treatment with sodium hexametaphosphate is performed, F, Impurities such as Na and P adhere to the phosphor, and on the contrary, they become impurities and cause a decrease in luminous efficiency after long-time use. Therefore, after the acid treatment or the elutriation classification treatment, it is effective to remove impurities by dispersing and washing the phosphor with an ultrasonic homogenizer in a solvent such as ion-exchanged water.

According to another aspect of the present invention, there is provided a light emitting element that includes a light emitting light source and a phosphor, and the phosphor is the above-described phosphor. As this light emitting light source, a monochromatic LED or LD having a peak intensity of emission wavelength of 240 nm or more and 480 nm or less is preferable. Monochromatic light having a peak wavelength of the light source of 240 nm or more and 480 nm or less is the wavelength range of blue LEDs most frequently used in actual use, and Li-α sialon has high fluorescence intensity when excited at a wavelength in the range. This is because light is emitted.

In one embodiment, the light-emitting element according to the present invention can have a luminous flux retention ratio of 95% or more when left at a current of 150 mA for 1000 hours under conditions of a temperature of 85 ° C. and a relative humidity of 85%. Can be 97% or more, more preferably 98% or more, for example, 95 to 99%.

In still another aspect, the present invention is a light emitting device including the light emitting element. Examples of the light emitting device include an information display device used outdoors such as a signal and an outdoor display device, and a lighting device replacing a headlight, an incandescent lamp, and a fluorescent lamp for an automobile.

A light emitting device including a phosphor and an LED according to the present invention can be manufactured as follows, for example. First, the phosphor according to the present invention is mixed with a sealing material to prepare a slurry. For example, the slurry can be adjusted by mixing at a ratio of 30 to 50 parts by mass with respect to 100 parts by mass of the sealing material. Examples of the sealing material include thermoplastic resins, thermosetting resins, and photocurable resins. Specifically, for example, methacrylic resin such as polymethylmethacrylate; styrene resin such as polystyrene and styrene-acrylonitrile copolymer; polycarbonate resin; polyester resin; phenoxy resin; butyral resin; polyvinyl alcohol; Cellulose resins such as cellulose acetate butyrate; epoxy resins; phenol resins; silicone resins. In addition, inorganic materials such as metal alkoxides, ceramic precursor polymers or solutions containing metal alkoxides are hydrolyzed by a sol-gel method or a combination thereof, and solidified inorganic materials such as siloxane bonds. It is also possible to use an inorganic material. In addition, a melt-processed glass can be used as long as it is a sealing part that can be attached externally without directly touching the LED chip (for example, an external cap, a dome-shaped sealing part, etc.). In addition, a sealing material may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Among sealing materials, it is preferable to use a resin having thermosetting properties and fluidity at room temperature for reasons of dispersibility and moldability. As the resin having thermosetting properties and fluidity at room temperature, for example, a silicone resin is used. For example, trade names: JCR6175, OE6631, OE6635, OE6636, OE6650, etc., manufactured by Toray Dow Corning Co., Ltd. can be mentioned.

Next, for example, 3 to 4 μL of the slurry is injected into a top view type package in which a blue LED chip having a peak wavelength at 460 nm is mounted. The top view type package into which this slurry has been injected is heated at a temperature in the range of 140 to 160 ° C. for a period of 2 to 2.5 hours to cure the slurry. In this manner, a light-emitting element that absorbs light in the wavelength range of 420 to 480 nm and emits light having a wavelength of more than 480 nm and not more than 800 nm can be manufactured.

[Examples] Examples according to the present invention will be described using a table while comparing with comparative examples.

<Example 1>
A method for manufacturing the phosphor of Example 1 will be described. The phosphor was manufactured through a raw material mixing step and a firing step.

(Mixing process)
The raw materials for the phosphor of Example 1 are Si ₃ N ₄ (E10 grade made by Ube Industries), AlN (F grade made by Tokuyama Corp.), Eu ₂ O ₃ (RU grade made by Shin-Etsu Chemical Co., Ltd.), Li ₃ N powder. (Purity 99.5% by mass, -60 mesh, manufactured by Material). These raw materials were weighed so as to have a molar ratio of Si ₃ N ₄ : AlN: Eu ₂ O ₃ = 84.5: 14.8: 0.64 and mixed to obtain a premixed powder.

The number of moles of the premixed powder in the nitrogen atmosphere (total number of moles of Si ₃ N ₄ , AlN, and Eu ₂ O ₃ ): the number of moles of Li ₃ N = 94.1: 5.9 The raw material mixed powder was obtained.

(Baking process)
The raw material mixed powder is filled in a boron nitride crucible in a glove box, and baked at 1800 ° C. for 8 hours in a nitrogen atmosphere with a gauge pressure of 0.8 MPa in an electric furnace of a carbon heater. Li-α sialon was obtained.

The Eu-activated Li-α sialon was pulverized by a dry pulverizer using a roll mill and a jet mill, and classified by passing through a sieve having an opening of 45 μm.

(Acid treatment process)
After classification, the Eu-activated Li-α sialon was acid-treated with a mixture of hydrofluoric acid and nitric acid (80 ° C.).

(Washing process)
The phosphor after the acid treatment step was mixed in a solvent such as ion-exchanged water and dispersed for 5 minutes with an ultrasonic homogenizer to remove impurities. Thereafter, suction filtration was performed.

<Example 2>
In Example 2, the following steps were added before the cleaning step in the manufacturing method of Example 1.

(Wet classification process)
The phosphor after the acid treatment step was allowed to stand in a mixed solvent of ion-exchanged water and sodium hexametaphosphate as a dispersant for 10 minutes to remove fine powder. The phosphor of Example 2 was manufactured through the above steps.

<Example 3>
Example 3 is a phosphor manufactured under the same conditions as in Example 2 except that the manufacturing method of Example 2 was dispersed for 1 hour during the cleaning process using an ultrasonic homogenizer.
<Example 4>
Example 4 is a phosphor produced under the same conditions as in Example 2 except that the manufacturing method of Example 2 was dispersed for 2 hours during the cleaning step using an ultrasonic homogenizer.
<Example 5>
In Example 5, the phosphor after the acid treatment step in the production method of Example 2 was mixed with ion-exchanged water and ammonia water from a washing treatment in a mixed solvent of ion-exchanged water and sodium hexametaphosphate as a dispersant. The phosphor was produced under the same conditions as in Example 2 except that the cleaning treatment was performed in a basic solvent.
<Example 6>
Example 6 is a phosphor manufactured under the same conditions as in Example 5 except that the cleaning process was performed before the wet classification process in the manufacturing method of Example 5.

<Comparative Example 1>
Comparative Example 1 was produced by the same production method except that the acid treatment step and the washing step were omitted in the production step of Example 1.

<Comparative example 2>
Comparative Example 2 was manufactured by the same manufacturing method except that the cleaning process was omitted in the manufacturing process of Example 1.

<Comparative Example 3>
Comparative Example 3 was produced by the same production method except that the acid treatment step and the washing step were omitted in the production step of Example 2.

<Comparative example 4>
Comparative Example 4 was manufactured by the same manufacturing method except that the cleaning process was omitted in the manufacturing process of Example 2.

<Comparative Example 5>
Comparative Example 5 was produced by the same production method except that the acid treatment step was omitted in the production method of Example 2.

<Comparative Example 6>
Comparative Example 6 was manufactured by the same manufacturing method except that the cleaning step was omitted in the manufacturing method of Example 5.

<Comparative Example 7>
The comparative example 7 differs from the comparative example 4 in that a Ca-α sialon-based phosphor is manufactured by using calcium nitride powder (Ca ₃ N ₂ ) as a lithium nitride (Li ₃ N) raw material. In addition, the pre-mixed powder ratio was silicon nitride powder: aluminum nitride powder: europium oxide powder = 71.6: 25.8: 2.6 (molar ratio) in molar ratio. This premixed powder was put in a glove box under a nitrogen atmosphere and mixed with calcium nitride powder to obtain a raw material mixed powder. The mixing ratio was the number of moles of the premixed powder (the total number of moles of Si ₃ N ₄ , AlN, and Eu ₂ O ₃ ): the number of moles of calcium nitride powder = 87.1: 12.9.

(Light emitting device manufacturing process)
Each phosphor according to the example and the comparative example after the washing step is mixed at a ratio of 30 parts by mass with respect to 100 parts by mass of silicone resin (manufactured by Toray Dow Corning Co., Ltd., trade name: JCR6175, etc.) Adjusted. Thereafter, 3 to 4 μL of the slurry was injected into a top view type package on which a blue LED chip having a peak wavelength at 460 nm was mounted. The top view type package into which this slurry was injected was heated at 150 ° C. for 2 hours to cure the slurry, thereby manufacturing a light emitting device.

Table 1 shows the evaluation of each phosphor according to Examples and Comparative Examples. Table 1 shows an impurity content (unit: mass ppm), a median diameter (unit: μm), a ratio of α sialon crystals to all crystal phases (unit: mass%), and a peak wavelength (unit: unit) for Examples and Comparative Examples. nm), fluorescence intensity (unit:%), and luminous flux retention (unit:%) of the LED.

(Identification of crystal phase and ratio of α-sialon crystal to all crystal phases)
About each fluorescent substance which concerns on an Example and a comparative example, the crystal phase was identified by the powder X-ray diffraction (XRD) using a CuK alpha ray using the X-ray-diffraction apparatus (UrigaIV by Rigaku Corporation). The X-ray diffraction patterns of the phosphors obtained in Examples 1 to 6 and Comparative Examples 1 to 6 showed the same diffraction pattern as that of α sialon crystals, and it was confirmed that the main crystal phase was α sialon. . Further, based on the diffraction pattern of the α sialon and the diffraction pattern of the impurity crystal phase, the mass ratio of the α sialon crystal to the total crystal phase was calculated. On the other hand, the diffraction pattern of α sialon was also observed in Comparative Example 7, confirming that the main crystal phase was α sialon.

(Impurity content)
Phosphorus, sodium and fluorine contents were analyzed by eluting 0.5 g of phosphor / 25 ml of water at 100 ° C. × 12 H and filtering, followed by analysis with an ICP emission spectrometer (CIROS-120, manufactured by Rigaku Corporation). .

(Median diameter (D50))
The median diameter (D50) (average primary particle diameter) of each phosphor according to Examples and Comparative Examples was measured as follows. First, a mixture of hydrofluoric acid (concentration in the range of 46 to 48 g / 100 ml) and nitric acid (concentration 60 g / 100 ml) at a ratio of 1: 1 was diluted 4 times with distilled water to prepare a treatment solution. While heating this processing liquid to 80 degreeC and stirring, the fluorescent substance of an Example or a comparative example was added and disperse | distributed the quantity of 20 g or less with respect to 100 ml of processing liquids. The phosphor was allowed to stand for 1 hour after dispersion, and the insoluble powder was recovered by decantation. The recovered insoluble powder was washed with water and dried. For the insoluble powder after drying, the particle size distribution was measured with a laser diffraction scattering type particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter, Inc.), and the 50% cumulative particle size based on volume was determined as the median diameter (D50). It was.

(Chemical composition)
In addition, as a result of analyzing the phosphor with an ICP emission spectroscopic analyzer (CIROS-120, manufactured by Rigaku Corporation), the Li content of the phosphors of Example 1 and Comparative Example 6 was 1.8% by mass or more 3 The Eu content was in the range of 0.1 to 1.5% by mass, and the O content was in the range of 0.4 to 1.3% by mass. .

(Peak wavelength)
For each of the phosphors according to Examples and Comparative Examples, fluorescence measurement was performed using a spectrofluorometer (F-7000, manufactured by Hitachi High-Technologies Corporation) corrected with rhodamine B and a sub-standard light source. For the measurement, a solid sample holder attached to the photometer was used, and a fluorescence spectrum and a peak wavelength at an excitation wavelength of 455 nm were measured.

(Fluorescence intensity)
The fluorescence intensity was calculated from the product of fluorescence spectrum intensity and CIE standard relative luminous efficiency. In addition, since it changes with measuring apparatuses and conditions, a unit is arbitrary and it compared by the relative in the Example and comparative example which were measured on the same conditions. As a reference, the fluorescence intensity of Example 4 was set to 100%. 85% or more is an acceptable value.

(Light flux retention rate of light emitting element (durability evaluation of light emitting element))
Next, the light beam change was measured about the light emitting element provided with the fluorescent substance particle which concerns on an Example and a comparative example. The change in luminous flux was measured by leaving the light emitting element at a high temperature and high humidity of 85 ° C. and 85% relative humidity at a current of 150 mA for a predetermined time, and then measuring the total luminous flux (Half Moon: HH41-0773 manufactured by Otsuka Electronics Co., Ltd.). -1) was used to measure the change in the luminous flux of the fluorescence emitted from the light emitting device. In addition, this shows the ratio when the current immediately after the start of energization as 100% from the value of the light flux for each energization time as the luminous flux retention rate, and it is preferably 95% or more after 1000 hours.

From Table 1, the Li-α sialon phosphors of Examples 1 to 6 had a lower impurity content and a higher proportion of α sialon crystals than the comparative examples. As a result, a high intensity of fluorescence was obtained, and even when used for a long time, the light emission efficiency was small and the light emitting device had few electrical defects. In the light-emitting elements using the phosphors according to Examples 1 to 6, since the content of the impurity element contained in the phosphor is extremely small, the occurrence of inhibition of resin curing caused by the impurity element of the phosphor is suppressed. Therefore, the possibility of causing an electrical abnormality such as a short circuit is extremely small and the life is long.

On the other hand, Comparative Example 1 had low fluorine, sodium, and phosphorus contents, but the proportion of α sialon crystals was low, so the fluorescence intensity was low. In Comparative Example 2, the sodium and phosphorus contents were low, but the fluorine content was high and the light flux retention was low. In Comparative Example 3, although the fluorine content was small, the sodium and phosphorus contents were large, the light flux retention was low, and the proportion of α sialon crystals was also low. In Comparative Example 4, the luminous flux retention was low because of the high phosphorus, sodium, and fluorine contents. In Comparative Example 5, the content of phosphorus, sodium, and fluorine was small, but the proportion of α-sialon crystals was low. For this reason, the luminous flux retention was reduced as compared with the inventive examples. In Comparative Example 6, the sodium and phosphorus contents were small, but the fluorine content was large, and the luminous flux retention was low. For this reason, the luminous flux retention was reduced as compared with the inventive examples. Although the comparative example 7 had many fluorine, sodium, and phosphorus content, the light beam retention rate was high. In other words, the presence of the impurity element does not necessarily have an adverse effect, and the deterioration of the characteristics due to the presence of the impurity element is peculiar to the Li-α sialon phosphor.

Claims

Eu-activated Li-α sialon-based phosphor having an F content of 20 mass ppm or less and a total content of P and Na of 10 mass ppm or less, and the ratio of α sialon crystals to the total crystal phase Whose phosphor is 95 mass% or more.
The phosphor according to claim 1, wherein the total content of P and Na is 5 mass ppm or less.
The phosphor according to claim 1 or 2, wherein the Li content is 1.8 mass% or more and 3 mass% or less.
The phosphor according to any one of claims 1 to 3, wherein the Eu content is 0.1 mass% or more and 1.5 mass% or less.
The phosphor according to any one of claims 1 to 4, wherein the O content is 0.4 mass% or more and 1.3 mass% or less.
6. The phosphor according to claim 1, wherein the average primary particle diameter is 7 μm or more and 35 μm or less.
A light-emitting element comprising: the phosphor according to any one of claims 1 to 6; and a light-emitting light source that irradiates the phosphor with excitation light.
The light emitting device according to claim 7, wherein the light emitting light source is a light emitting diode or a laser diode.
The light-emitting element according to claim 7 or 8, wherein a light beam retention rate is 95% or more when left under a condition of a temperature of 85 ° C and a relative humidity of 85% and a current of 150 mA for 1000 hours.
A light-emitting device comprising the light-emitting element according to any one of claims 7 to 9.