TW201802230A - Phosphor, light-emitting element, and light-emitting device - Google Patents

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-[alpha]-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 [alpha]-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 relates to a light-emitting element including a phosphor. The present invention relates to a light-emitting device including a light-emitting element.

Conventionally, as a phosphor that emits orange light, Ca ^{2+ is} used as a general formula: Ca _x Eu _y Si _{12- (m + n)} Al _{(m + n)} O _n N _16-n . Ca-α-sialon phosphors that stabilize metal ions with a crystal structure are known, and high luminous efficiency can be obtained (see Patent Document 1). In the light-emitting device provided with the α-sialon phosphor using Ca ²⁺ , the problem of “lower light-emitting efficiency of the light-emitting device” does not occur when it is used for a long time.

On the other hand, in recent years, enhancement of brightness and shortening of the fluorescence spectrum have been discussed, and Li ⁺ α-Sialon phosphors using Li ⁺ as a metal ion for stabilizing the crystal structure have been proposed (see Patent Documents 2 to 4). ). Therefore, compared with a light-emitting device using a Ca-α-sialon phosphor, although the brightness of the light-emitting device is improved and the wavelength is shortened due to the inclusion of a Li-α-sialon phosphor, it has been used for a long time. In this case, the deterioration of the resin used as the sealing material of the LED package is considered to be due to the ionization of the impurity elements contained in the phosphor; and because the above-mentioned resin is deteriorated, the light-emitting efficiency of the light-emitting device is reduced, so it has a new problem. (See Patent Document 5).

On the other hand, regarding the same nitrogen oxide-based phosphors as α-sialon, which is one of the red light-emitting phosphors, that is, CASN-based phosphors, as reported in Patent Documents 6 to 7, they include by A halogen element which is not an element constituting a crystalline phase has high luminous efficiency. Therefore, it can be known that an element other than the element constituting a crystalline phase does not necessarily cause adverse effects.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-363554

[Patent Document 2] International Publication No. 2007/004493

[Patent Document 3] International Publication No. 2010/018873

[Patent Document 4] Japanese Patent Laid-Open No. 2010-202738

[Patent Document 5] Japanese Patent Laid-Open No. 2009-224754

[Patent Document 6] Japanese Patent Laid-Open No. 2010-18771

[Patent Document 7] Japanese Patent Publication No. 2012-512307

In this way, although various discussions have been made on the improvement of the characteristics of Li-α-sialon-based phosphors, there is still room for improvement in reducing the luminous efficiency due to long-term use. The object of the present invention is to provide a light-emitting device with high fluorescence intensity and hardly decreasing luminous efficiency even after long-term use, and to provide a phosphor for achieving this purpose.

One aspect of the present invention is a Eu-activated Li-α Sailon phosphor It is a phosphor whose F content is 20 mass ppm or less, and the total content of P and Na is 10 mass ppm or less. The ratio of the α-sialon crystal to the total crystalline phase is 95 mass% or more.

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

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

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

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

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

Another aspect of the present invention is a light-emitting element having the phosphor of the present invention and a light-emitting light source that irradiates the phosphor with excitation light.

In one embodiment of the light-emitting element of the present invention, the light-emitting light source is a light-emitting diode or a laser diode.

In another embodiment of the light-emitting element of the present invention, under conditions of a temperature of 85 ° C. and a relative humidity of 85%, when the current is kept at 150 mA for 1000 hours, the beam retention rate is above 95%.

Another aspect of the present invention is a light-emitting device including the light-emitting element of the present invention.

In the present invention, for Eu-activated Li-α-sialon-based phosphors, on the one hand, the ratio of α-sialon crystals to the fully crystalline phase is increased; Reduce the content of F, Na and P. By using the phosphor of the present invention, a high fluorescence intensity can be obtained, and at the same time, a light-emitting device that can hardly reduce the luminous efficiency even when used for a long time can be obtained.

[Form of Implementing Invention]

In one aspect, the present invention relates to Eu-activated Li-α sialon-based phosphors. Eu-activated Li-α Sialon-based phosphors generally have the following formula: Li _x Eu _y Si _{12- (m + n)} Al _{m + n} O _n N _16-n (x + y ≦ 2, m = x + 2y). In this phosphor, a part of the Si-N bond of the α-silicon nitride crystal is replaced with an Al-N bond and an Al-O bond, and Li and Eu penetrate into the solid solution in the crystal while maintaining an electrically neutral state Voids; m and n values correspond to the substitution rates for Al-N and Al-O bonds, respectively.

The purpose of using Li ^{+ in the} present invention is not to shorten the wavelength in the past, but to obtain a higher fluorescence intensity than in the case of Ca ²⁺ . The solid solution composition range of α-sialon is not only limited by the number of solid solution positions of the stabilized cation, but also by thermodynamic stability corresponding to the stabilized 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 value of n is 0 or more and 0.5 or less. If the Li content in the phosphor of the present invention is too small, the particle growth progresses very slowly during the phosphor sintering step, and it tends to be difficult to obtain large particles with high fluorescence intensity; if it is too large, LiSi is generated The tendency of other phases such as ₂ N ₃ is preferably 1.8% by mass or more and 3% by mass or less. The Li content can be adjusted by the phosphor-doped raw material. Specifically, it can be adjusted by increasing or decreasing the blending ratio of lithium nitride and lithium oxide as Li-containing raw materials.

If the Eu content in the phosphor of the present invention is too small, the contribution to luminescence will tend to be small and the fluorescence intensity will be low; if it is too large, the energy transfer between Eu ^{2+ will} cause the fluorescence concentration to be extinct, Furthermore, since the fluorescence intensity tends to become low, it is preferably from 0.1% by mass to 1.5% by mass. The Eu content can be adjusted by using a phosphor-doped raw material. Specifically, it can be adjusted by increasing or decreasing the blending ratio of erbium oxide and erbium nitride of Eu-containing raw materials.

The content of oxygen (O) in the phosphor of the present invention is preferably from 0.4% by mass to 1.3% by mass. This is because phosphors with too little oxygen content have little grain growth during the manufacturing process and cannot obtain high fluorescence intensity. If too much oxygen content, the fluorescence spectrum is broadened and sufficient fluorescence intensity cannot be obtained.

In order to obtain a phosphor that has almost no decrease in luminous efficiency even after long-term use, the content of F in the impurity elements of the phosphor is preferably 20 mass ppm or less, more preferably 10 mass ppm or less, and even more preferably 5 mass ppm or less. The mass ppm or less may be, for example, 1 to 20 mass ppm. As described in the latter paragraph, since the α-sialon crystal ratio of the phosphor can be increased to improve the luminescence characteristics, it is effective to perform acid treatment on the phosphor, but F is an element that is easily mixed during the acid treatment. It is difficult to sufficiently improve the light-emitting characteristics only by performing the acid treatment, so removing F after the acid treatment is important for continuously obtaining excellent light-emitting efficiency.

In addition, in order to suppress the decrease in the luminous efficiency of a light-emitting device provided with a phosphor, and to reduce the occurrence of electrical defects under long-term use, It is desired to further suppress the total content of P and Na. Specifically, the total content of P and Na is preferably 10 mass ppm or less, more preferably 5 mass ppm or less, and even more preferably 2 mass ppm or less. For example, it may be 1 to 5 mass ppm. As described later, since increasing the α-Sialon crystal ratio of the phosphor can improve the light emitting characteristics, it is effective to remove the fine powder system of the phosphor by classification. Classification can use wet classification, which uses sodium hexamethyl phosphate as a dispersant, but this method is easy to mix P and Na. Therefore, in this case, it is difficult to sufficiently improve the light emitting characteristics only by performing classification. Therefore, after the classification, removing Na and P is important for continuously obtaining excellent light emitting efficiency. In order to further suppress the P content and the Na content and reduce the burden on the washing step after the classification step, the classification step is preferably a wet classification using an alkaline solvent, or a dry classification.

The phosphor of the present invention is for the purpose of fine-tuning the fluorescence characteristics, and can maintain the neutrality of electricity, and replace part of Li in the general formula with a member selected from the group consisting of Mg, Ca, Y, and lanthanides (excluding La , Ce, Eu) in the group consisting of one or more types of substitution elements. Therefore, in one embodiment of the Eu-activated Li-αSialon-based phosphor, a part of Li is replaced by one or more of the above-mentioned substitution elements.

As long as the phosphor of the present invention does not affect the fluorescence characteristics, as a crystalline phase existing in the phosphor, it may include not only an α-sialon single phase, but also silicon nitride, aluminum nitride, lithium silicon nitride, The crystalline phase of such solid solutions. However, in general, the ratio of α-sialon in the phosphor is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 98% by mass or more, and for example, it may be 95 to 99% by mass. %.

If the average primary particle diameter in the phosphor of the present invention is too small, If the fluorescence intensity is too low, the chromaticity of the luminous color will be uneven when the phosphor is mounted on the light-emitting surface of the LED, and the luminous color will be colored. Therefore, it is preferably 7 μm or more. 35 μm or less. The average primary particle diameter here refers to the volume-based median diameter (D50) by the laser diffraction and scattering method.

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

First, phosphor raw materials other than silicon nitride powder, aluminum nitride powder, and lithium nitride powder such as hafnium oxide are mixed in a desired ratio. When industrial productivity is considered, it is preferable to mix by wet mixing. After wet mixing, the solvent is removed, dried and pulverized to obtain a pre-mixed powder. This premixed powder and lithium nitride powder are mixed in a desired ratio, whereby a raw material mixed powder can be obtained. In order to suppress hydrolysis, it is preferable to perform mixing under a nitrogen atmosphere or the like.

By sintering the raw material mixed powder, Eu-activated Li-α-sialon can be obtained. The crucible used in the sintering is preferably made of a material that is stable in a high temperature environment, and is preferably made of a high melting point metal such as boron nitride, carbon, molybdenum, or tantalum. The sintering environment is not particularly limited, but is generally performed in an inert gas environment or a reducing environment. Only one kind of inert gas or reducing gas may be used, and two or more kinds may be used in any combination and proportion. Examples of the inert gas or reducing gas include hydrogen, nitrogen, argon, and ammonia. Among them, a nitrogen atmosphere is preferred. The pressure of the sintering environment can be selected according to the sintering temperature. The more environmental pressure High, the decomposition temperature of the phosphor is higher, but considering industrial productivity, it is preferably performed under a pressure of about 0.02 to 1.0 MPa in gauge pressure. If the sintering temperature is lower than 1650 ° C, the crystal defects and unreacted residual amount of the matrix crystal will increase, and if it exceeds 1900 ° C, the matrix will be decomposed, which is not preferable. Therefore, the sintering temperature is preferably 1650 to 1900 ° C. If the sintering time is short, the crystal defects and unreacted residual amount of the parent crystal are high, and if the sintering time is long, it is not good considering industrial productivity. Therefore, it is preferably 2 to 24 hours. The obtained Eu-activated Li-α-sialon can also be classified into a desired particle size according to demand.

Eu-activated Li-α-sialon obtained from sintering. Generally speaking, the ratio of α-sialon is low, so it is difficult to exhibit excellent fluorescence intensity. Therefore, it is preferable to perform acid treatment with a mixed solution of hydrofluoric acid and nitric acid, etc., so as to increase the crystallization ratio of α-sialon.

In this way, if the particle size of the phosphor is too small, the fluorescence intensity tends to be low. In order to obtain a high-luminance phosphor, it is preferable to perform a classification step for removing fine powder after the acid treatment step. The classification step can be either wet or dry, but elutriation classification or dry classification is preferred. The elutriation classification is to place the phosphor in ion-exchanged water and sodium hexamethylphosphate as a dispersant. In a mixed solvent or in a mixed alkaline solvent of ion-exchanged water and ammonia.

Through the acid treatment and classification steps, the crystallization ratio of α-sialon can be increased, but if acid treatment is performed with a mixed solution of hydrofluoric acid and nitric acid, etc., and elutriation classification treatment is performed with sodium hexamethyl phosphate, F, Na and P Other impurities are attached to the phosphor, and these elements become impurities instead, which may cause a decrease in luminous efficiency after long-term use. So, Yu Jin After acid treatment and elutriation and classification treatment, the phosphor is dispersed and washed in a solvent such as ion-exchanged water in an ultrasonic homogenizer, which can effectively remove impurities.

In another aspect, the present invention is a light-emitting element having a light-emitting light source and a phosphor, and the phosphor system described above is a phosphor. As the light-emitting light source, an LED or an LD having monochromatic light having a peak intensity of emission wavelengths of 240 nm to 480 nm is preferable. Monochromatic light with a peak wavelength of 240nm to 480nm is the wavelength region of the blue LED most widely used in practical use. In addition, if Li-αSialon is excited at a wavelength in this range, High fluorescence intensity glow.

In one embodiment of the light-emitting device of the present invention, under conditions of a temperature of 85 ° C. and a relative humidity of 85%, when the current is 150 mA and left for 1000 hours, the beam retention rate can be more than 95%. Above 97%, more preferably above 98%, for example, between 95% and 99%.

In 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 an illumination device that replaces an automobile headlight, incandescent lamp, fluorescent light, or the like.

The light-emitting element including the phosphor and the LED of the present invention can be produced, for example, by the following method. First, the phosphor of the present invention is mixed with a sealing material, and the slurry is adjusted. For example, the slurry can be adjusted by mixing 30 to 50 parts by mass with respect to 100 parts by mass of the sealing material. Examples of the sealing material include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Specific examples include methacrylic resins such as polymethyl methacrylate; polystyrene and styrene-acrylonitrile Copolymers, such as styrene resins; polycarbonate resins; polyester resins; phenoxy resins; butyral resins; polyvinyl alcohol; ethyl cellulose, cellulose acetate, cellulose acetate butyrate, etc. Cellulose resin; epoxy resin; phenol resin; silicone resin, etc. In addition, for the inorganic material, for example, a solution obtained by hydrolyzing and polymerizing a solution containing a metal alkoxide, a ceramic precursor polymer, or a metal alkoxide by a sol-gel method, or a combination of these can be used. The cured inorganic material is, for example, an inorganic material having a siloxane bond. Moreover, if it is a sealing part (for example, an external cap, a dome-shaped sealing part, etc.) which can be externally mounted without directly contacting an LED chip, a fusion glass can also be used. In addition, one type of sealing material may be used, and two or more types may be used in any combination and proportion.

Among the sealing materials, for reasons of dispersibility and moldability, it is preferable to use a resin having thermosetting properties and fluidity at normal temperature. As the resin having thermosetting property and fluidity at ordinary temperature, for example, a silicone resin can be used. For example, Dow Corning Toray Co., Ltd. can be listed, and product names are JCR6175, OE6631, OE6635, OE6636, OE6650, and the like.

Next, for example, in a forward-type package in which a blue LED wafer having a peak wavelength of 460 nm is mounted, 3 to 4 μL of the slurry is injected. At a temperature in the range of 140 to 160 ° C., in a range of 2 to 2.5 hours, the forward-type package injected with the slurry is heated to harden the slurry. In this way, a light-emitting element that absorbs light in a wavelength range of 420 to 480 nm and emits light having a wavelength in excess of 480 nm to 800 nm can be manufactured.

[Example]

On the one hand, the embodiments and comparative examples of the present invention are compared. Use the table to explain.

<Example 1>

A method for manufacturing the phosphor of Example 1 will be described. A phosphor is manufactured through a raw material mixing step and a sintering step.

(Mixing step)

The raw materials of the phosphor of Example 1 are Si ₃ N ₄ (E10 grade manufactured by Ube Kosan Co., Ltd.), AlN (F grade manufactured by TOKUYAMA Corporation), Eu ₂ O ₃ (RU grade manufactured by Shin-Etsu Chemical Industry Co., Ltd.), and Li ₃ N Powder (99.5% by mass, -60 mesh by Materion). The raw materials were weighed and mixed so that the mol ratio was Si ₃ N ₄ : AlN: Eu ₂ O ₃ = 84.5: 14.8: 0.64 to obtain a pre-mixed powder.

Under a nitrogen environment, mix in a manner such that the molar number of the premixed powder (the total molar number of Si ₃ N ₄ , AlN, and Eu ₂ O ₃ ): the molar number of Li ₃ N = 94.1: 5.9 The powder was pre-mixed to obtain a raw material mixed powder.

(Sintering step)

In the glove box, the raw material mixed powder was filled into a boron nitride crucible, and sintered at 1800 ° C. for 8 hours in an electric furnace made of carbon heater under a pressure nitrogen atmosphere of 0.8 MPa gauge. And Eu-activated Li-α sialon was obtained.

This Eu-activated Li-α-sialon was pulverized with a dry pulverizer such as a roll mill or a jet mill, and was pressed and passed through a sieve with a mesh size of 45 μm to pass through it and classified.

(Acid treatment step)

Activation of classified Eu with a mixture of hydrofluoric acid and nitric acid (80 ° C) Li-α-sialon is acid-treated.

(Washing step)

The phosphor after the acid treatment step is mixed with a solvent such as ion-exchanged water and dispersed in an ultrasonic homogenizer for 5 minutes, thereby removing impurities. After suction filtration.

<Example 2>

Example 2 is the manufacturing method of Example 1, and the following steps were added before the washing step.

(Wet classification step)

The phosphor after the acid treatment step was left to stand in a mixed solvent of ion-exchanged water and sodium hexamethylphosphate as a dispersant for 10 minutes to remove fine powder. By the above steps, the phosphor of Example 2 was manufactured.

<Example 3>

In Example 3, the phosphor was produced under the same conditions as in Example 2 except that it was dispersed for 1 hour when the washing step was performed with an ultrasonic homogenizer in the manufacturing method of Example 2.

<Example 4>

Example 4 is a phosphor produced under the same conditions as in Example 2 except that it was dispersed for 2 hours when the washing step was performed with an ultrasonic homogenizer in the manufacturing method of Example 2.

<Example 5>

Example 5 was changed from "the washing treatment of the phosphor after the acid treatment step in a mixed solvent of ion-exchanged water and sodium hexamethylphosphate as a dispersant" in the manufacturing method of Example 2 to "in Fluorescence of the phosphor after acid treatment in a mixed alkaline solvent of ion-exchanged water and ammonia. The cleaning process was performed except for the phosphors produced under the same conditions as in Example 2.

<Example 6>

Example 6 is a phosphor manufactured under the same conditions as in Example 5 except that the washing step is performed before the wet classification step in the manufacturing method of Example 5.

<Comparative example 1>

Comparative Example 1 was performed in the same manufacturing method except that the acid treatment step and the washing step were omitted from the manufacturing steps of Example 1.

<Comparative example 2>

Comparative Example 2 was performed by the same manufacturing method except that the washing step was omitted from the manufacturing step of Example 1.

<Comparative example 3>

Comparative Example 3 was performed in the same manufacturing method except that the acid treatment step and the washing step were omitted from the manufacturing steps of Example 2.

<Comparative Example 4>

Comparative Example 4 was performed by the same manufacturing method except that the washing step was omitted in the manufacturing step of Example 2.

<Comparative example 5>

Comparative Example 5 was performed by the same manufacturing method except that the acid treatment step was omitted in the manufacturing method of Example 2.

<Comparative Example 6>

Comparative Example 6 was performed by the same manufacturing method except that the washing step was omitted in the manufacturing method of Example 5.

<Comparative Example 7>

Comparative Example 7 differs from Comparative Example 4 in that a lithium nitride (Li ₃ N) raw material is used as a calcium nitride powder (Ca ₃ N ₂ ) to produce a Ca-α Sialon-based phosphor. In addition, the ratio of the pre-mixed powder is in terms of molar ratio, silicon nitride powder: aluminum nitride powder: hafnium oxide powder = 71.6: 25.8: 2.6 (molar ratio). This pre-mixed powder was placed in a glove box under a nitrogen environment, and mixed with the calcium nitride powder to obtain a raw material mixed powder. The mixing ratio is the molar number of the premixed powder (total molar numbers of Si ₃ N ₄ , AlN, and Eu ₂ O ₃ ): the molar number of the calcium nitride powder = 87.1: 12.9.

(Light-emitting element manufacturing steps)

The phosphors of the examples and the comparative examples after the washing step were mixed in a proportion of 30 parts by mass with respect to 100 parts by mass of a silicone resin (manufactured by Dow Corning Toray Co., Ltd., trade name: JCR6175, etc.) Adjust the slurry. Thereafter, 3 to 4 μL of the slurry was injected into a forward type package mounted with a blue LED chip having a peak wavelength at 460 nm. The forward-type package injected with the slurry was heated at 150 ° C for 2 hours to harden the slurry to produce a light-emitting element.

The evaluation of each phosphor in the examples and comparative examples is shown in Table 1. Table 1 shows the content of impurities (unit: mass ppm), median diameter (unit: μm), ratio of α-sialon crystal to the total crystalline phase (unit: mass%), and peak wavelength (for the examples and comparative examples). Unit: nm), fluorescence intensity (unit:%), beam retention rate of LED (unit:%).

(Identification of crystalline phase and ratio of α-sialon crystal to fully crystalline phase)

For each phosphor of the examples and comparative examples, an X-ray diffraction device was used (Ultima IV, manufactured by Rigaku Co., Ltd.), the powder phase was identified by powder X-ray diffraction (XRD) using CuKα rays. The X-ray diffraction patterns of the phosphors obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were confirmed to be the same diffraction pattern as the α-sialon crystal, and it was confirmed that the main crystal phase was α-sialon. In addition, 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 fully crystalline phase was calculated. On the other hand, in Comparative Example 7, the diffraction pattern of α-sialon was also confirmed, and it was confirmed that the main crystal phase was α-sialon.

(Impurity content)

The phosphor was eluted at 100 ° C. × 12H at 0.5 g / 25 ml of water and filtered. Then, the content of phosphorus, sodium, and fluorine was analyzed by an ICP emission spectrophotometer (CIROS-120 manufactured by Rigaku Co., Ltd.).

(Median diameter (D50))

The median diameter (D50) (average primary particle diameter) of each phosphor in the examples and comparative examples was measured in the following manner. First, hydrofluoric acid (concentration of 46 to 48 g / 100 ml) and nitric acid (concentration of 60 g / 100 ml) were mixed 1: 1, and then diluted to 4 times with distilled water to prepare a treatment solution. This treatment liquid was heated to 80 ° C, and the phosphors of Examples or Comparative Examples were added and dispersed in an amount of 20 g or less with respect to 100 ml of the treatment liquid while stirring. After dispersing the phosphor, it was allowed to stand for 1 hour, 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 by a laser diffraction scattering type particle size distribution measuring device (LS 13 320 manufactured by BECKMAN COULTER Co., Ltd.), and a 50% volume-based cumulative particle diameter was used as the median diameter D50).

(chemical components)

In addition, a phosphor analysis was performed by an ICP emission spectroscopic analyzer (CIROS-120, manufactured by Rigaku Co., Ltd.). As a result, the Li content of the phosphors of Examples 1 and 6 was 1.8% by mass or more and 3% by mass. In the range of not more than 0.1%, the content of Eu is in the range of 0.1% by mass to 1.5% by mass, and the content of O is in the range of 0.4% by mass to 1.3% by mass.

(Peak wavelength)

For each phosphor of the examples and comparative examples, a spectrofluorimeter (F-7000, manufactured by Hitachi High-Technologies, Ltd.) corrected by Rhodamine B and a sub-standard light source was used for fluorescence emission. Determination. In the measurement, a solid sample carrier attached to the photometer was used to measure the fluorescence spectrum and the peak wavelength at an excitation wavelength of 455 nm.

(Fluorescence intensity)

Calculate the fluorescence intensity from the product of the fluorescence spectrum intensity and the CIE standard luminosity function. In addition, since it varies depending on the measurement device and conditions, it is an arbitrary unit, and it is compared with the relative conditions under the examples and comparative examples measured under the same conditions. The fluorescence intensity of Example 4 was set to 100% as a reference. More than 85% are qualified.

(Beam retention rate of light emitting element (durability evaluation of light emitting element))

Next, a light-emitting element including the phosphor particles of Examples and Comparative Examples was measured for a change in light flux. The measurement of the change of the light beam is performed at a temperature of 85 ° C and a relative humidity of 85% at a high temperature and high humidity. The light-emitting element is energized at 150 mA and left for a predetermined time. A full-beam measurement system (Half Moon: HH41-0773-1 (manufactured by Otsuka Electronics Co., Ltd.), and measured the change in the light flux of the fluorescent light emitted from the light emitting element. In addition, this is a beam value per unit of energization time, and the ratio at 100% after the start of energization is expressed as a beam retention ratio, and after 1000 hours, it is preferably 95% or more.

As can be seen from Table 1, the Li-α-sialon-based phosphors of Examples 1 to 6 have a lower impurity content than that of the comparative example, and the proportion of α-sialon crystals is also high. Thereby, while obtaining high fluorescence intensity, even if it is used for a long time, there is less reduction in luminous efficiency, and it is a light emitting device with less electrical failure. Since the light-emitting element using the phosphors of Examples 1 to 6 has a very small amount of impurity elements contained in the phosphors, the resin hardening caused by the impurity elements of the phosphors is inhibited, so that The possibility of causing electrical abnormalities such as short circuits is extremely small, and the life is prolonged.

In contrast, in Comparative Example 1, although the content of fluorine, sodium, and phosphorus was small, the ratio of α-sialon crystals was low, so the fluorescence intensity was low. In Comparative Example 2, although the content of sodium and phosphorus was small, the content of fluorine was high, and the beam retention was also low. In Comparative Example 3, although the content of fluorine is small, the content of sodium and phosphorus is high, the beam retention rate is also low, and the ratio of α-sialon crystals is also low. In Comparative Example 4, since the content of phosphorus, sodium, and fluorine was high, the beam retention was low. In Comparative Example 5, the content of phosphorus, sodium, and fluorine was small, and the proportion of α-sialon crystals was low. Therefore, the beam holding ratio is lower than that of the invention example. In Comparative Example 6, although the content of sodium and phosphorus was small, the content of fluorine was high and the beam retention was low. Therefore, the beam holding ratio is lower than that of the invention example. In Comparative Example 7, although the contents of fluorine, sodium, and phosphorus were high, the beam retention was still high. That is, the presence of an impurity element does not necessarily cause an adverse effect, and the phenomenon that the characteristics are reduced due to the presence of an impurity element is a phenomenon unique to Li-α-sialon-based phosphors.

Claims (10)

A phosphor, which is an Eu-activated Li-αSialon-based phosphor, in which the F content is 20 mass ppm or less, and the total content of P and Na is 10 mass ppm or less. The α-Sialon crystal is relatively The proportion is more than 95% by mass. For example, the phosphor of claim 1, wherein the total content of P and Na is 5 mass ppm or less. For the phosphor of claim 1 or 2, the Li content is 1.8 mass% or more and 3 mass% or less. For the phosphor of claim 1 or 2, the Eu content is 0.1 mass% or more and 1.5 mass% or less. For the phosphor of claim 1 or 2, the content of O is 0.4 mass% or more and 1.3 mass% or less. If the phosphor of claim 1 or 2 has an average primary particle size of 7 μm or more and 35 μm or less. A light-emitting element includes: a 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 element according to claim 7, wherein the light-emitting source is a light-emitting diode or a laser diode. For example, the light-emitting element of claim 7 or 8, wherein under the condition of a temperature of 85 ° C. and a relative humidity of 85%, 150 mA is applied and left for 1000 hours, the beam retention rate is above 95%. A light emitting device including the light emitting element according to any one of claims 7 to 9.