JP2017210580A - Fluophor, manufacturing method therefor and light-emitting device using the fluophor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluophor having improved initial light emission intensity maintenance factor and a light-emitting device using the fluophor.SOLUTION: There is provided a silicofluoride fluophor having intensity ratio of intensity of a maximum peak Iexisting in a range of 3570 to 3610 cmto intensity of a maximum peak Iexisting in a range of 1200 to 1240 cmin an infrared absorption spectrum, Iof 0.01 or less, and octahedron ECoN with a site occupied by silicon or manganese as a center and fluorine sites are apexes of 5.6 to 6.0 when Rietveld analyzed under a condition by setting a powder X ray diffraction profile with a crystal structure having crystal system of a monoclinic crystal, spaces of P1 and face-centered symmetric property.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a phosphor, a manufacturing method thereof, and a light-emitting device using the phosphor.

  A light-emitting diode (LED) light-emitting device is mainly composed of a combination of an LED chip as an excitation light source and a phosphor, and various combinations of emission colors can be realized.

In a white LED light emitting device that emits white light, a combination of an LED chip that emits light in a blue region and a phosphor is used. For example, a combination of an LED chip that emits blue light and a phosphor mixture may be mentioned. As the phosphor, a yellow light-emitting phosphor that mainly emits yellow light that is a complementary color of blue is used, and is used as a pseudo-white light LED light-emitting device. In addition, a three-wavelength white LED using an LED chip that emits blue light, a green or yellow light emitting phosphor, and a red light emitting phosphor has been developed. A K ₂ SiF ₆ : Mn phosphor is known as one of red light emitting phosphors used in such a light emitting device.

  Conventionally known fluoride phosphors tend to have lower emission intensity over time than the initial emission intensity when they are continuously excited to emit light. When a phosphor is used in a light emitting device, it is desirable that the change in emission intensity with time is small, that is, the emission intensity maintenance rate is high. For this reason, improvement of the luminous intensity maintenance rate of fluorescent substance is desired. In order to meet such needs, there is a report that the surface of the phosphor is treated with a treatment liquid containing a surface treatment agent such as an organic amine or an ammonium salt, and durability is improved by a high temperature and high humidity test. However, such a method requires a step of further processing the phosphor once synthesized, and another method is desired to reduce the manufacturing cost of the phosphor. Furthermore, since conventionally known fluoride phosphors generally tend to have lower emission intensity when in contact with moisture, it is not preferable to perform surface treatment using a treatment agent containing moisture as described above after synthesis. .

Special table 2009-528429 gazette JP 2014-141684 A

  An object of the embodiment of the present invention is to provide a phosphor having an improved emission intensity maintenance rate without reducing the emission intensity of the phosphor, and a light emitting device using the phosphor.

（式中、ｗ_iは以下の一般式（Ｃ）で表され；

式中、ｌ_ｉは前記八面体の６つのケイ素（またはマンガン）−フッ素間結合のうち、ｉ（ｉ＝１，２，３，４，５，６）番目の結合の結合長であり、ｌ_ａｖは以下の一般式（Ｄ）で表され；

式中、ｌ_ｍｉｎは前記八面体中の６つのケイ素（またはマンガン）−フッ素間結合長の中の最小値を示すものである）
が５．６以上６．０以下であることを特徴とするものである。 The phosphor according to the embodiment has the following general formula (A):
_{(K 1-p / k,} M p / k) a (Si 1-x-y, Ti x, Mn y) F b (A)
(here,
M is at least one selected from the group consisting of Na and Ca,
k is a number indicating the valence of M and is 1 or 2,
1.5 ≦ a ≦ 2.5,
5.0 ≦ b ≦ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3, and 0 <y ≦ 0.06
Is)
A phosphor represented by
In the infrared absorption spectrum, the maximum peak ratio _I IR ₌ I 2 / _{I 1} of the intensity _{I 2} of the present in the range of 3570～3610Cm ^-1 to the intensity _{I 1} of the maximum peak present in the range of 1200～1240Cm ^-1 A powder X-ray diffraction profile of a crystal structure having an octahedral structure centered on a site occupied by silicon or manganese and having a fluorine site at the top is a monoclinic crystal system. When the average crystal structure is determined by Rietveld analysis under the conditions set with the crystal structure having face-center symmetry and the space group is P1, the effective coordination number ECoN defined by the following general formula (B) ;

Wherein w _i is represented by the following general formula (C);

In the formula, l _i is the bond length of the i-th (i = 1, 2, 3, 4, 5, 6) bond among the six silicon (or manganese) -fluorine bonds of the octahedron, _av is represented by the following general formula (D);

In the formula, l _min represents the minimum value among the six silicon (or manganese) -fluorine bond lengths in the octahedron)
Is 5.6 or more and 6.0 or less.

  The light emitting device according to the embodiment includes a light emitting element that emits light having a peak in a wavelength region of 440 nm or more and 470 nm or less, and a phosphor layer containing the phosphor. Is.

The figure which shows the infrared absorption spectrum of the fluorescent substance by embodiment. The enlarged view of the infrared absorption spectrum (800-1600cm < ^-1 >) of the fluorescent substance by embodiment. The enlarged view of the infrared absorption spectrum (2500-4000cm < ^-1 >) of the fluorescent substance by embodiment before and behind a dehydration process. The figure which shows the relationship between the effective coordination number ECoN of the fluorescent substance by embodiment, and internal quantum efficiency. Sectional drawing of the light-emitting device by embodiment. Sectional drawing of the light-emitting device by other embodiment.

  Hereinafter, embodiments will be described in detail. The embodiment described below shows a phosphor and a light emitting device for embodying the technical idea of the present invention, and the present invention is not limited to the following examples.

  As a result of intensive studies and studies on a phosphor mainly composed of potassium silicofluoride and activated by manganese, the present inventors have identified the phosphor in the infrared absorption spectrum (hereinafter sometimes referred to as IR spectrum). It was found that the intensity ratio of the peak and the specific crystal structure correlate with the luminous efficiency of the phosphor and the emission intensity maintenance rate of the phosphor.

In the embodiment, a preferable phosphor has a composition represented by the following general formula (A).
_{(K 1-p / k,} M p / k) a (Si 1-x-y, Ti x, Mn y) F b (A)
(Where
M is at least one selected from the group consisting of Na and Ca,
k is a number indicating the valence of M and is 1 or 2,
1.5 ≦ a ≦ 2.5,
5.0 ≦ b ≦ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3, and 0 <y ≦ 0.06
Is)

  The phosphor according to the embodiment contains manganese as an activator. In order to make this phosphor a red light-emitting phosphor, the valence of manganese is preferably +4. Other valences of manganese may be included, but the proportion is preferably small and most preferably all manganese is +4.

  When manganese is not contained (y = 0), light emission cannot be confirmed even when excited by light having an emission peak in the ultraviolet to blue region. Therefore, x in the general formula (A) needs to be larger than 0. Moreover, when the manganese content increases, the luminous efficiency tends to be improved, and y is preferably 0.005 or more.

  However, when the manganese content is too large, a concentration quenching phenomenon occurs, and the emission intensity of the phosphor tends to be weakened. In order to avoid such inconvenience, the manganese content ratio (y) is preferably 0.06 or less, and more preferably 0.05 or less.

Further, as described above, the phosphor according to the embodiment may contain elements other than the main constituent elements K, Si, F, and Mn. As an element to be contained, for example, a small amount of Na, Ca, Ti or the like may be contained. Even when these elements are contained in a small amount, the phosphor exhibits an emission spectrum similar to the red region, and can achieve a desired effect. However, the content of these elements is preferably small from the viewpoint of the stability of the phosphor, the cost of synthesizing the reactive phosphor during phosphor synthesis, and the like. Moreover, elements other than those exemplified here may be contained as inevitable components. Even in such a case, the effect of the embodiment is generally sufficiently exhibited.
Note that the phosphor according to the embodiment may contain a different phase or impurities in addition to the main phase. At this time, it is preferable that not only the composition of the whole phosphor but also the composition of the main phase satisfy the general formula (A).

  In order to analyze the content of each element with respect to the entire phosphor, for example, the following method may be mentioned. Metal elements such as K, Na, Ca, Si, Ti, and Mn are obtained by subjecting the synthesized phosphor to alkali melting and, for example, using an IRIS Advantage type ICP emission spectroscopic analyzer (trade name, manufactured by Thermo Fisher Scientific). It can be analyzed by ICP emission spectroscopy. Moreover, the nonmetallic element F can isolate | separate the fluorescent substance which was synthesize | combined by thermal hydrolysis, for example, can be analyzed with DX-120 type | mold ion chromatograph analyzer (a brand name, Nippon Dionex Co., Ltd. product). Further, F can be analyzed by ion chromatography after alkali melting as in the case of the metal element described above.

  The phosphor according to the embodiment does not contain oxygen stoichiometrically. However, oxygen may be inevitably mixed into the phosphor during the phosphor synthesis process or due to decomposition of the phosphor surface after synthesis. It is desirable that the oxygen content in the phosphor is zero, but if the ratio of [oxygen content] / [(fluorine content) + (oxygen content)] is less than 0.05, light emission It is preferable because the efficiency is not greatly impaired.

Conventionally, a fluoride phosphor having a basic structure containing potassium, silicon, and fluorine and activated with manganese is used as a light emitting device, and when the light emitting device is operated continuously, the phosphor emits light. In general, the intensity decreases with time, and color deviation of light emission occurs. Various methods for solving such problems have been studied, but all have room for improvement. In contrast, the present inventors have found that those phosphors exhibiting a specific IR spectrum exhibit excellent characteristics. Specifically, in the IR spectrum, it is that the maximum peak intensity (hereinafter _{I 2} present in 3570～3610Cm ^-1 to the maximum peak intensity (hereinafter sometimes referred _{I 1)} present in 1200～1240Cm ^-1 A phosphor having a ratio I _IR (I ₂ / I ₁ ) of 0.01 or less exhibits excellent characteristics.

Such an intensity ratio of the IR spectrum is considered to correspond to the content of various OH groups present in the phosphor. That is, as will be described later, the peak existing at 3570 to 3610 cm ⁻¹ corresponds to the natural vibration of the OH bond of the isolated OH group, and the vicinity of 3200 cm ⁻¹ is the OH bond included in the water molecule included around the phosphor. Presumed to correspond to natural vibration. And when the said intensity ratio in IR spectrum of fluorescent substance has in a specific range, ie, when there are few OH bonds contained in fluorescent substance, it is thought that the outstanding characteristic is shown.

Although the measuring method of IR spectrum is not specifically limited, For example, it can measure with infrared spectroscopy apparatuses, such as a VERTEX70V FT-IR spectrometer (brand name, Bruker Optics make). The measurement conditions can be, for example, as follows.
Wave number resolution: 4 cm ⁻¹
Number of sample scans: 100 times Measurement wave number range: 350 to 4000 cm ⁻¹
Measurement atmosphere: Vacuum detector: TGS (DTGS) detector

The IR spectrum measurement method includes a transmission method, a reflection method, an ATR method, etc., but the phosphor according to this embodiment is generally a powder having a particle diameter of several μm to 60 μm, and sample preparation is easy. It is preferable to carry out by a diffuse reflection method capable of measurement. The diffuse reflection method is generally measured by diluting to an appropriate concentration (about 1 to 10%) with a diluent such as KBr or KCl that is light transmissive in the infrared region. in IR spectrum of the phosphor in, for peak intensity in the vicinity of 3590cm around ^-1, and 3220Cm ^-1 is small, it is preferable to carry out the measurement without using the above diluent. However, in the background measurement, it is preferable to perform the measurement using the diluent.

An example of the IR spectrum of the phosphor according to the present embodiment is shown in FIG. FIG. 2 is an enlarged view of the IR spectrum of FIG. 1 from 800 to 1600 cm ⁻¹ . FIG. 2 also shows the IR spectrum of K ₂ SiF ₆ powder in which Mn is not activated (for example, a commercially available deer grade reagent manufactured by Kanto Chemical). From FIG. 2, the peak of 800 to 1600 cm ⁻¹ is observed at substantially the same position in the phosphor activated with Mn and the K ₂ SiF ₆ powder not activated with Mn. Recognize. From this, it is considered that the peak in the vicinity of 800 to 1600 cm ⁻¹ in the phosphor activated with Mn corresponds to the vibration mode inherent to the K ₂ SiF ₆ crystal that is the base material.

FIG. 3 is an enlarged view of 2500 to 4000 cm ⁻¹ of the IR spectrum of FIG. It can be seen from FIG. 3 that in the phosphor of the embodiment, almost no peak is detected in this range. On the other hand, the conventional silicon fluoride phosphor not subjected to the internal dehydration treatment of particles generally has a vibration peak in such a range. That is, when the phosphor according to the embodiment is manufactured, it is preferable to form a phosphor crystal in an aqueous medium and then dehydrate the specific phosphor particles (details will be described later). In such a phosphor before dehydration treatment inside the phosphor particles, sharp vibration peaks can be confirmed in the vicinity of 3720, 3630, and 3590 cm ⁻¹ . Furthermore, a broad vibration peak is confirmed at 2500-3500 cm < ^-1 >. The former vibration peak is considered to be a peak peculiar to the isolated OH group present in the phosphor. The latter broad vibration peak is considered to be a peak attributed to an OH bond contained in a water molecule that is adsorbed to a phosphor crystal, or has a hydrogen bond or a coordinate bond. The present embodiment has been completed based on the knowledge that there is a correlation between the sharp maximum peak intensity (I ₂ ) existing at 3570 to 3610 cm ⁻¹ and the characteristics of the phosphor.

However, since IR measurement is generally used for qualitative evaluation, it is difficult to quantitatively evaluate the sharp maximum peak existing in 3570 to 3610 cm ^−1. It is difficult to specify the correlation with the characteristics of Therefore, in the embodiment, the obtained IR spectrum is based on the maximum peak existing at 1200 to 1240 cm ⁻¹ considered to be attributed to the inherent vibration mode of the K ₂ SiF ₆ crystal, and 3570 to 3610 cm relative thereto. The relative intensity (I _IR = I ₂ / I ₁ ) of the maximum peak existing at ^-1 was used as an index.

The aforementioned maximum peak position (wave number) in the IR spectrum may vary depending on the phosphor composition and phosphor synthesis conditions. In the present embodiment, the peak position in the vicinity of 1220 cm ⁻¹ is an important factor, but this peak position can vary by ± 15 cm ⁻¹ under preferable conditions and ± 5 cm ⁻¹ under more preferable conditions. is there.
In order to perform measurement in a wide wave number range, it is preferable to use a TGS (DTGS) detector with high response linearity.

In the present embodiment, when the relative intensity I _IR value is 0.01 or less, when the phosphor is used in the light emitting device, the change in the emission intensity with time during continuous operation is small, that is, the emission intensity. A high retention rate was found. In the present embodiment, when the relative intensity I _IR value is in the above range, the detailed reason why the phosphor exhibits excellent characteristics has not been sufficiently elucidated. However, it is estimated as follows. When a phosphor based on a general fluoride is incorporated into a light emitting device and operated, the phosphor becomes hot during operation, and as a result, hydrolysis involving isolated OH groups contained in the phosphor occurs. It is estimated that a decrease in strength occurs. On the other hand, in the phosphor according to the embodiment, since the content of the isolated OH group is small, it is estimated that hydrolysis does not occur and the decrease in emission intensity is also small.

The relative intensity I _IR is preferably 0.01 or less, more preferably 0.005 or less, and still more preferably 0.002 or less. Most preferably, no peak exists in the range of 3570 to 3610 cm ⁻¹ , that is, I ₂ = I _IR = 0.

  The phosphor according to the embodiment can be manufactured by any method. For example, the phosphor can be manufactured by the method described below.

The phosphor having the composition represented by the general formula (A) dissolves a mixture of hexafluorosilicate (H ₂ SiF ₆ ), potassium hexafluoromanganate (K ₂ MnF ₆ ), sodium hexafluoromanganate and the like. It can be produced by a method such as a coprecipitation method in which a potassium-containing raw material is added to a hydrofluoric acid aqueous solution and reacted. Other methods include reacting Si source and Ti source with potassium permanganate in an aqueous hydrofluoric acid solution, or potassium in a solution in which hexafluorosilicic acid and potassium hexafluoromanganate (K ₂ MnF ₆ ) are dissolved. It is possible to synthesize by a method such as adding a source and reacting, or a poor solvent precipitation method. In any manufacturing method, the basic phosphor can be obtained through a drying process such as suction filtration after being synthesized in an aqueous solution using hydrofluoric acid.

  According to the study by the present inventors, water molecules adsorbed on isolated OH groups or the surface of the phosphor are unavoidable even in the phosphor after drying treatment such as suction filtration. It was found that it was included. Although it is possible to reduce the amount of water contained in isolated OH groups and phosphors to some extent by selecting synthesis methods and optimizing synthesis parameters, it is possible to completely remove isolated OH groups and water molecules only by examining the synthesis method. It is not easy to remove. Therefore, in order to remove the above-mentioned isolated OH groups and water molecules, after the synthesis of the basic phosphor described above, the drying treatment is performed as necessary, and then the dehydration treatment inside the phosphor particles is performed. OH groups and water molecules can be removed. The dehydration treatment inside the phosphor particles is preferably performed at a temperature range of 200 ° C. or more and 800 ° C. or less, a pressure range of 0.0003 atmospheres or more and 8 atmospheres or less, and a treatment time of 1 minute or more and 24 hours or less. More preferably, they are 200 degreeC or more and 750 degrees C or less, 0.01 atmospheres or more and 6 atmospheres or less, 5 minutes or more and 10 hours or less. Further, the atmosphere for performing the dehydration treatment inside the phosphor particles can be carried out in a nitrogen, argon, helium, fluorine atmosphere or the like.

However, if an excessive dehydration treatment is performed inside the phosphor particles in order to remove isolated OH groups and water molecules and lower the _IIR value, it is considered that a part of the phosphor is denatured or oxidized. For the reason of avoiding denaturation or oxidation, conventionally, the phosphor formed in an aqueous medium is generally not heated until it is dehydrated by actively heating or depressurizing. In the embodiment, in order to avoid such modification or oxidation of the phosphor, it is possible to control by adjusting the temperature, pressure, and atmosphere in the dehydration step inside the phosphor particles after synthesis.

（式中、ｗ_iは以下の一般式（Ｃ）で表され；

式中、ｌ_ｉは前記八面体の６つのケイ素（またはマンガン）−フッ素間結合のうち、ｉ（ｉ＝１，２，３，４，５，６）番目の結合の結合長であり、ｌ_ａｖは以下の一般式（Ｄ）で表され；

式中、ｌ_ｍｉｎは前記八面体中の６つのケイ素（またはマンガン）−フッ素間結合長の中の最小値を示すものである）
なお、解析対象とする粉末Ｘ線回折プロファイルは実測値であり、測定される結晶は、前記一般式（Ａ）で表される主相のほかに、異相や不純物も含むことがある。これらの含有量は相対的に少ないので、一般的には無視し得るが、測定された粉末Ｘ線回折プロファイルが、既知である主相とは明らかに異なる形状を有する場合には、主相に対応しないプロファイル形状（ピーク）を除外して解析することができる。 FIG. 4 shows the relationship between the effective coordination number ECoN of the phosphor and the internal quantum efficiency. Here, the effective coordination number ECoN is a physical quantity representing the distortion of the coordination polyhedron. For example, when the crystal structure is a perfect octahedron, there is no distortion and ECoN is 6. ECoN decreases when the crystal structure is distorted, and takes a smaller value as the strain increases. Here, specifically, ECoN is a powder X-ray diffraction profile with respect to a crystal structure having an octahedral structure centered on a site occupied by silicon or manganese and having a fluorine site as a vertex. When the average crystal structure is determined by Rietveld analysis under the conditions set as the crystal structure having face-centered symmetry with the space group of P1, it is defined by the following general formula (B).

Wherein w _i is represented by the following general formula (C);

In the formula, l _i is the bond length of the i-th (i = 1, 2, 3, 4, 5, 6) bond among the six silicon (or manganese) -fluorine bonds of the octahedron, _av is represented by the following general formula (D);

In the formula, l _min represents the minimum value among the six silicon (or manganese) -fluorine bond lengths in the octahedron)
Note that the powder X-ray diffraction profile to be analyzed is an actual measurement value, and the crystal to be measured may contain a different phase or impurities in addition to the main phase represented by the general formula (A). Since these contents are relatively small, they are generally negligible, but if the measured powder X-ray diffraction profile has a shape that is clearly different from the known main phase, Analysis can be performed by excluding incompatible profile shapes (peaks).

式中
Ｅ（λ）：蛍光体へ照射した励起光源の全スペクトル（フォトン数換算）
Ｒ（λ）：蛍光体の励起光源反射光スペクトル（フォトン数換算）
Ｐ（λ）：蛍光体の発光スペクトル（フォトン数換算）
である。 Further, the absorption rate of the phosphor and the internal quantum efficiency η ′ are calculated by the following equations.

In the formula, E (λ): the entire spectrum of the excitation light source irradiated to the phosphor (photon number conversion)
R (λ): Excitation light source reflected light spectrum of phosphor (photon number conversion)
P (λ): emission spectrum of phosphor (in terms of photon number)
It is.

  The absorption rate and internal quantum efficiency of the phosphor can be measured by, for example, a C9920-02G type absolute PL quantum yield measuring apparatus (trade name, manufactured by Hamamatsu Photonics Co., Ltd.). As the excitation light for measuring the matrix coloring, a peak wavelength near 650 nm and a half width of 5 to 10 nm can be used. Further, blue light having a peak wavelength of around 440 to 470 nm and a half width of 5 to 15 nm can be used as excitation light when measuring the internal quantum efficiency.

  In order to use the phosphor according to the embodiment for a light emitting device or the like, the internal quantum efficiency is preferably 70% or more. FIG. 4 shows that the internal quantum efficiency increases as ECoN increases. In order to achieve an internal quantum efficiency of 70% or higher, ECoN is preferably 5.6 or higher, more preferably 5.8 or higher. Further, the maximum value of ECoN is 6.0 by definition. In addition, FIG. 4 shows that the higher the ECoN of the phosphor represented by the general formula (A), the higher the quantum efficiency. Therefore, it is preferable that ECoN is high. In order to achieve such high ECoN, various methods can be taken. As one of the methods for achieving high ECoN, it is preferable to optimize the dehydration conditions inside the phosphor particles.

  Moreover, the phosphor according to the embodiment can be classified according to the coating method to the light emitting device to be used. In ordinary white LEDs using excitation light having an emission peak in the blue region, it is generally preferable to use phosphor particles classified to 1 to 50 μm. If the particle size of the phosphor after classification is excessively small, the emission intensity may decrease. On the other hand, if the particle size is excessively large, the phosphor may be clogged in the phosphor layer coating device when it is applied to the LED, resulting in a decrease in work efficiency and yield, and color unevenness of the completed light emitting device.

  The phosphor according to the embodiment can be excited by an excitation light source having an emission peak in the ultraviolet to blue region. When this phosphor is used in a light emitting device, it is desirable to use a light emitting element having an emission peak in a wavelength region of 440 nm or more and 470 nm or less from the excitation spectrum of the phosphor as an excitation light source. Use of a light emitting element having a light emission peak outside the above wavelength range is not preferable from the viewpoint of light emission efficiency. As the light emitting element, a solid light source element such as an LED chip or a laser diode can be used.

  The phosphor according to the embodiment is a phosphor that emits red light. Therefore, when blue light is used as the excitation light source, a white light emitting device can be obtained by using it in combination with a green light emitting phosphor and a yellow light emitting phosphor. When ultraviolet light is used as the excitation light source, a white light emitting device can be obtained by using a combination of a blue light emitting phosphor, a green light emitting phosphor, and a yellow light emitting phosphor. The type of phosphor to be used can be arbitrarily selected according to the purpose of the light emitting device. For example, when providing a white light emitting device for lighting use with a low color temperature, by combining the phosphor according to the embodiment and the yellow light emitting phosphor, a light emitting device having both efficiency and color rendering can be provided.

It can be said that the green light emitting phosphor and the yellow light emitting phosphor are phosphors having a main emission peak in a wavelength region of 520 nm or more and 570 nm or less. Examples of such phosphors include silicate phosphors such as (Sr, Ca, Ba) ₂ SiO ₄ : Eu, Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Aluminate phosphors such as Ce, (Ca, Sr, Ba) Ga ₂ S ₄ : Sulfide phosphors such as Eu, (Ca, Sr, Ba) Si ₂ O ₂ Examples include alkaline earth oxynitride phosphors such as N ₂ : Eu, Eu-activated (Ca, Sr) -αSiAlON, βSiAlON, and the like. The main emission peak is a wavelength at which the peak intensity of the emission spectrum is maximized, and the emission peak of the exemplified phosphor has been reported in the literature so far. Note that a change in emission peak of about 10 nm may be observed due to the addition of a small amount of elements or a slight compositional change during the preparation of the phosphor, and such a phosphor is also included in the phosphors exemplified above. Shall.

  It can be said that the blue light-emitting phosphor has a main emission peak in a wavelength region of 440 nm to 500 nm. For example, halophosphate phosphors such as (Sr, Ca, Ba, Mg) 5 (PO4) 3 (Cl, Br): Eu, (Sr, Ca, Ba, Mg) 5 (PO4) 3Cl: Eu, 2SrO · Examples thereof include phosphate phosphors such as 0.84P2O5 · 0.16B2O3: Eu, and alkaline earth metal aluminate phosphors such as BaMgAl10O17: Eu.

In addition, in the light emitting device using the phosphor according to the embodiment, an orange light emitting phosphor and a red light emitting phosphor other than the above can be used depending on the application.
As the orange-emitting phosphor and red-emitting phosphor, silicate phosphors such as (Sr, Ca, Ba) ₂ SiO ₄ : Eu, tungstate phosphors such as Li (Eu, Sm) W ₂ O ₈ , ( La, Gd, Y) ₂ O ₂ S: oxysulfide phosphors such as Eu, (Ca, Sr, Ba) S: sulfide phosphors such as Eu, (Sr, Ba, Ca) ₂ Si ₅ N ₈ : Examples thereof include nitride phosphors such as Eu and (Sr, Ca) AlSiN ₃ : Eu. By using these phosphors in combination with the phosphors according to the embodiments, not only the efficiency but also the color rendering properties for illumination applications and the color gamut for backlight applications can be further improved. However, when the number of phosphors used is too large, reabsorption / light emission phenomenon and scattering phenomenon in which the phosphors absorb and emit light occur, and the light emission efficiency of the light emitting device decreases.

  FIG. 5 shows a cross section of the light emitting device according to the embodiment. The light-emitting device illustrated includes a lead 100, a lead 101 and a stem 102, a semiconductor light-emitting element 103, a reflective surface 104, and a phosphor layer 105. A semiconductor light emitting element 103 is mounted with Ag paste or the like at the bottom center. As the semiconductor light emitting element 103, an element that emits ultraviolet light or an element that emits light in the visible region can be used. For example, it is possible to use semiconductor light emitting diodes such as GaAs and GaN. The arrangement of the lead 100 and the lead 101 can be changed as appropriate. A phosphor layer 105 is disposed in the recess of the light emitting device. The phosphor layer 105 can be formed by dispersing the phosphor according to the embodiment in a resin layer made of, for example, a silicone resin at a ratio of 5 wt% to 80 wt%.

  As the semiconductor light emitting element 103, a flip chip type having an n-type electrode and a p-type electrode on the same surface can be used. In this case, problems caused by the wires such as wire breakage and peeling and light absorption by the wires are solved, and a highly reliable and high-luminance semiconductor light-emitting device can be obtained. In addition, an n-type substrate may be used for the semiconductor light emitting element 103 to have the following configuration. Specifically, an n-type electrode is formed on the back surface of the n-type substrate, a p-type electrode is formed on the upper surface of the semiconductor layer on the substrate, and the n-type electrode or the p-type electrode is mounted on a lead. The p-type electrode or the n-type electrode can be connected to the other lead by a wire. The size of the semiconductor light emitting element 103 and the dimensions and shape of the recesses can be changed as appropriate.

FIG. 6 shows an example of a bullet-type light emitting device. The semiconductor light emitting element 201 is mounted on the lead 200 ′ via the mount material 202 and covered with the pre-dip material 204. The lead 200 is connected to the semiconductor light emitting element 201 by a bonding wire 203 and is encapsulated with a casting material 205. The pre-dip material 204 contains the phosphor according to the embodiment.
As described above, the light emitting device according to the embodiment, for example, the white LED is not only suitable for general illumination, but also as a light emitting device used in combination with a color filter, for example, a light source for a liquid crystal backlight. Specifically, it can also be used as a red light emitting material for an inorganic electroluminescent device using a liquid crystal backlight source or a blue light emitting layer.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further in detail, this invention is not limited to a following example, unless the meaning is exceeded.

[Example 1, Comparative Example 1]
After KMnO ₄ powder and KF powder were dissolved in an HF aqueous solution, K ₂ MnF ₆ was synthesized by gradually dropping the H ₂ O ₂ aqueous solution and causing sufficient reaction in the HF aqueous solution. The synthesized K ₂ MnF ₆ was suction filtered to obtain K ₂ MnF ₆ powder. Further, to dissolve the SiO ₂ powder in HF _solution, to adjust the H 2 SiF ₆ solution. Furthermore, KF powder was dissolved in HF aqueous solution to prepare KF aqueous solution. The synthesized K ₂ MnF ₆ powder was dissolved in the adjusted H ₂ SiF ₆ solution to prepare a reaction solution. K ₂ SiF ₆ : Mn was synthesized by dropping a preliminarily prepared KF aqueous solution into the prepared reaction solution and allowing the reaction solution to sufficiently react. Synthesized K ₂ SiF ₆ : Mn was suction filtered to obtain a phosphor powder (Comparative Example 1). The composition analysis of the synthesized phosphor was K _2.03 (Si _0.98 , Mn _0.02 ) F ₆ . Further, in order to completely remove isolated OH groups and water molecules from the synthesized phosphor, a dehydration treatment inside the phosphor particles was performed (Example 1).

The IR spectra of Example 1 and Comparative Example 1 were measured. The intensity I _{IR of the} maximum peak existing in the range of 3570 to 3610 cm ⁻¹ with respect to the intensity of the maximum peak existing in the range of 1200 to 1240 cm ⁻¹ in the infrared absorption spectrum of Example 1 and Comparative Example 1, the internal quantum efficiency is It was as shown in Table 1.
For the IR spectrum measurement, a VERTEX70V FT-IR spectrometer (trade name, manufactured by Bruker Optics) was used. The detection limit of I _IR by this apparatus is 0.001, and when it is below the detection limit, Table 3 describes it as 0.001 or less. Moreover, after pulverizing these samples in a mortar, powder X-ray diffraction measurement was performed using SmartLab (trade name, manufactured by Rigaku). The measurement used the concentration method and swept 2θ in the range of 5-140 degrees. The obtained powder X-ray diffraction profile is defined as a crystal structure having face-centered symmetry, in which the atomic coordinates shown in Table 1 are the initial structure, the crystal system is monoclinic, and the space group is P1. Rietveld analysis was performed using PDXL II (trade name, manufactured by Rigaku) to refine the average structure. At this time, the a-axis length, b-axis length and c-axis length of the average crystal structure were 8.1419 mm, and α, β and γ were 90.000 °. The R factor representing the convergence of the analysis was Rwp of 5.39 and S of 1.40.

Table 1 corresponds to the fractional coordinates of an ideal octahedral structure crystal. That is, the coordinates of each element of the unit cell can be obtained by expanding the partial coordinates in Table 1 according to the symmetry of the space group as belonging to the space group P1. From the results in Table 1, the effective coordination number ECoN in the octahedral crystal structure centered on the Si / Mn site and having six F sites as vertices was calculated based on the above formula. At this time, the value of the effective coordination number ECoN was 6.

Similarly, Table 2 shows the atomic coordinates of the crystal according to Example 1 obtained after analysis of the powder X-ray diffraction profile. The a-axis length, b-axis length, and c-axis length of the average crystal structure at this time are 8.1130 (7) Å, 8.152 (2) お よ び, and 8.142 (2) Å, respectively, α, β and γ were 90.10 (3) °, 90.14 (3) °, and 90.06 (3) °. From the results in Table 2, the effective coordination number ECoN of the octahedron centered on the Si / Mn site and having six F sites as vertices was calculated based on the above formula. The results are as shown in Table 3.

  The phosphors of Example 1 and Comparative Example 1 were mixed with a resin and sealed on a GaN-based LED light-emitting element to obtain a light-emitting device. For each light-emitting device, current was injected into each LED, and the light-emitting device was continuously lit. The behavior of the emission intensity of the phosphors of Example 1 and Comparative Example 1 was observed. The emission intensity maintenance rates after 500 hours and 1000 hours were as shown in Table 3. From this result, it can be understood that in the phosphor according to the embodiment, a decrease in emission intensity when the light emitting device is used is suppressed.

Next, phosphors were synthesized by the same method as in Comparative Example 1, and the phosphors of Examples 2 to 6 with different drying conditions were synthesized. Table 3 shows I _IR , ECoN and internal quantum efficiency in the phosphor. Table 3 shows the emission intensity maintenance rates of the light emitting devices in which the phosphors of Examples 2 to 6 were mixed with the resin and sealed on the GaN LED light emitting elements.

これらの結果より、Ｉ_ＩＲが０．０１以下であり、かつＥＣｏＮが０．５６以上である場合には、内部量子効率が実用上十分に高く、同時に発光強度維持率も高いことがわかる。

From these results, it is understood that when the I _IR is 0.01 or less and the ECoN is 0.56 or more, the internal quantum efficiency is practically sufficiently high and the emission intensity maintenance rate is also high.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 100 and 101 ... Lead, 102 ... Stem, 103 ... Semiconductor light emitting element, 104 ... Reflecting surface, 105 ... Phosphor layer, 200 and 200 '... Lead, 201 ... Semiconductor light emitting element, 202 ... Mounting material, 203 ... Bonding wire, 204 ... Pre-dip material, 205 ... Casting material

Claims (9)

The following general formula (A):
_{(K 1-p / k,} M p / k) a (Si 1-x-y, Ti x, Mn y) F b (A)
(here,
M is at least one selected from the group consisting of Na and Ca,
k is a number indicating the valence of M and is 1 or 2,
1.5 ≦ a ≦ 2.5,
5.0 ≦ b ≦ 6.5,
0 ≦ p / k ≦ 0.1,
0 ≦ x ≦ 0.3, and 0 <y ≦ 0.06
Is)
A phosphor represented by
In the infrared absorption spectrum, the maximum peak ratio _I IR ₌ I 2 / _{I 1} of the intensity _{I 2} of the present in the range of 3570～3610Cm ^-1 to the intensity _{I 1} of the maximum peak present in the range of 1200～1240Cm ^-1 A powder X-ray diffraction profile of a crystal structure having an octahedral structure centered on a site occupied by silicon or manganese and having a fluorine site at the top is a monoclinic crystal system. When the average crystal structure is determined by Rietveld analysis under the conditions set with the crystal structure having face-center symmetry and the space group is P1, the effective coordination number ECoN defined by the following general formula (B) ;

Wherein w _i is represented by the following general formula (C);

In the formula, l _i is the bond length of the i-th (i = 1, 2, 3, 4, 5, 6) bond among the six silicon (or manganese) -fluorine bonds of the octahedron, _av is represented by the following general formula (D);

In the formula, l _min represents the minimum value among the six silicon (or manganese) -fluorine bond lengths in the octahedron)
The phosphor is characterized by having a 5.6 or more and 6.0 or less. The phosphor according to claim 1, wherein the I _IR is 0 or more and 0.005 or less.   The phosphor according to claim 1 or 2, wherein in the general formula (A), p / k = 0 and x = 0.   The phosphor according to claim 1, wherein an internal quantum efficiency η ′ of the phosphor is 70% or more.   A light emitting device comprising: a light emitting element that emits light having a peak in a wavelength region of 440 nm or more and 470 nm or less; and a phosphor layer that includes the phosphor according to claim 1. apparatus.   The apparatus according to claim 5, wherein the phosphor layer further includes a phosphor having an emission peak in a wavelength region of 520 nm or more and 570 nm or less. It is the manufacturing method of the fluorescent substance as described in any one of Claims 1-4, Comprising: The following processes (A) (i) Si containing raw material and Ti containing raw material are combined with potassium permanganate and sodium permanganate. (Ii) a potassium-containing raw material in a hydrofluoric acid aqueous solution in which a mixture of hexafluorosilicic acid and potassium hexafluoromanganate or sodium hexafluoromanganate is dissolved. Step (B) synthesized by a coprecipitation method or a poor solvent precipitation method in which a sodium-containing raw material is added and reacted with the phosphor synthesized at (A) in an inert gas at 200 ° C. to 800 ° C. A method comprising a step of internal dehydration.   The method for producing a phosphor according to claim 7, wherein the step of dehydrating the inside of the phosphor is performed at 0.0003 atm or more and 8 atm or less.   The method for producing a phosphor according to claim 7 or 8, wherein the inert gas is nitrogen, argon, or helium gas.

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