JP2017155209A - Manufacturing method of nitride phosphor, nitride phosphor and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a nitride phosphor less in change of chromaticity even under high temperature and high humidity and excellent in durability, a nitride phosphor and a light-emitting device.SOLUTION: There is provided a manufacturing method of a nitride phosphor having a composition containing at least one element selected from a group consisting of Ca, Sr, Ba and Mg, at least one element selected from a group consisting of Li, Na and K, at least one element selected from a group consisting of Eu, Ce, Tb and Mn, Al and N, including preparing a burned product having the composition, and contacting the burned product with a fluorine-containing material for a heat treatment at a temperature of 200°C to 500°C. There is provided a nitride phosphor having a layer of a compound containing fluorine on a surface of a phosphor core having the composition.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for manufacturing a nitride phosphor, a nitride phosphor, and a light emitting device.

  A light emitting device formed by combining a light emitting diode (hereinafter referred to as “LED”) and a phosphor is actively used for a backlight of a lighting device, a liquid crystal display device, and the like. It is out. For example, when a light emitting device is used in a liquid crystal display device, it is desired to use a phosphor having a narrow half-value width in order to increase the color reproduction range.

As such a phosphor, there is a nitride phosphor that emits red light and has a composition represented by SrLiAl ₃ N ₄ : Eu (hereinafter sometimes referred to as “SLAN phosphor”). And Non-Patent Document 1 (Philipp Pust et al. “Narrow-band red-emitting Sr [LiAl ₃ N ₄ ]: Eu ²⁺ as a next-generation LED-phosphor material” Nature Materials, NMAT4012, VOL13 September 2014) A SLAN phosphor having a narrow half-value width of 70 nm or less and an emission peak wavelength near 650 nm is disclosed.

In SLAN phosphor, for example, in Non-Patent Document 1, a raw material powder containing lithium aluminum hydride (LiAlH ₄ ), aluminum nitride (AlN), strontium hydride (SrH ₂ ), and europium fluoride (EuF ₃ ) is used. Weigh and mix at a stoichiometric ratio such that Eu is 0.4 mol%, and then put into a crucible, and calcinate under atmospheric pressure of a mixed gas atmosphere of hydrogen and nitrogen at a temperature of 1000 ° C. and a calcination time of 2 hours. It is manufactured by.

Special table 2015-526532 gazette

Philipp Pust et al. “Narrow-band red-emitting Sr [LiAl3N4]: Eu2 + as a next-generation LED-phosphor material” Nature Materials, NMAT4012, VOL13 September 2014

However, it is known that the SLAN phosphor easily deteriorates due to oxygen, heat, moisture, etc., and further improvement in durability of a light emitting device using such a SLAN phosphor has been demanded.
Therefore, an object of one embodiment of the present invention is to provide a nitride phosphor manufacturing method, a nitride phosphor, and a light-emitting device that can be a light-emitting device with excellent durability.

Specific means for solving the above problems are as follows, and the present invention includes the following embodiments.
The first embodiment of the present invention includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and at least one element selected from the group consisting of Li, Na and K; A method for producing a nitride phosphor having a composition containing at least one element selected from the group consisting of Eu, Ce, Tb, and Mn, Al, and N, and preparing a fired product having the composition And a fired product and a fluorine-containing substance are brought into contact with each other and heat-treated at a temperature of 200 ° C. or higher and 500 ° C. or lower.

  In a second embodiment of the present invention, at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and at least one element selected from the group consisting of Li, Na and K, A compound containing fluorine on the surface of the phosphor core having a composition containing at least one element selected from the group consisting of Eu, Ce, Tb and Mn, Al and N, and optionally containing Si. This is a nitride phosphor having the following layers.

  The third embodiment of the present invention is a light emitting device including the nitride phosphor and an excitation light source.

  According to one embodiment of the present invention, it is possible to provide a nitride phosphor manufacturing method, a nitride phosphor, and a light emitting device that are excellent in durability.

FIG. 1 is a schematic cross-sectional view illustrating an example of a light emitting device. FIG. 2 is a diagram comparing the X-ray diffraction patterns of the nitride phosphors of Examples and Comparative Examples of the present invention and the compounds of Reference Examples (SrF ₂ , LiSrAlF ₆ ). FIG. 3 is a diagram showing an emission spectrum showing the relative emission intensity with respect to the wavelength of the nitride phosphors of the examples and comparative examples of the present invention. 4 is an SEM photograph of a secondary electron image of the nitride phosphor according to Example 1. FIG. FIG. 5 is an SEM photograph of a secondary electron image of the nitride phosphor according to Comparative Example 1. 6 is an SEM photograph of a secondary electron image of the nitride phosphor according to Example 5. FIG. FIG. 7 is a SEM photograph of the backscattered electron image of the nitride phosphor according to Example 5. FIG. 8 is an SEM photograph of a secondary electron image of the nitride phosphor according to Comparative Example 3. FIG. 9 is an SEM photograph of a reflected electron image of a cross section of the nitride phosphor according to Comparative Example 3.

  Hereinafter, the method for manufacturing a nitride phosphor, the nitride phosphor, and the light emitting device according to the present disclosure will be described. However, the embodiment described below exemplifies a method for manufacturing a nitride phosphor for embodying the technical idea of the present invention, and the present invention includes the following method for manufacturing a nitride phosphor. It is not limited to. The relationship between the color name and the chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Moreover, content of each component in a composition means the total amount of the said some substance which exists in a composition, unless there is particular notice, when the substance applicable to each component exists in a composition in multiple numbers.

(Nitride phosphor manufacturing method)
The method for manufacturing a nitride phosphor according to an embodiment of the present invention includes at least one element selected from the group consisting of Ca, Sr, Ba, and Mg, and at least selected from the group consisting of Li, Na, and K. A method for producing a nitride phosphor having a composition containing one element, at least one element selected from the group consisting of Eu, Ce, Tb, and Mn, Al, and N, wherein Preparing a fired product having a temperature of 200 ° C. to 500 ° C., and bringing the fired product into contact with the fluorine-containing material.

[Process for preparing fired products]
The fired product prepared in the manufacturing method of the present embodiment includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and at least one type selected from the group consisting of Li, Na and K. There is no particular limitation as long as it has a composition including an element, at least one element selected from the group consisting of Eu, Ce, Tb, and Mn, Al, and N. The composition of the fired product may contain Si in a part of Al, may contain O due to oxidation of the surface, and part of N may be replaced by O.

The fired product preferably has a composition represented by the following general formula (I). Further, in the composition represented by the following general formula (I), a part of N may be replaced with O due to surface oxidation.
_{^{M a v M b w M c}} x Al 3-y Si y N z (I)
(In the formula, M ^a is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M ^b is at least one type selected from the group consisting of Li, Na and K. M ^c is at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and v, w, x, y and z are 0.80 ≦ v ≦ 1. 05, 0.80 ≦ w ≦ 1.05, 0.001 <x ≦ 0.1, 0 ≦ y ≦ 0.5, 3.0 ≦ z ≦ 5.0.)

In formula (I), M ^a preferably contains at least one of Ca and Sr from the viewpoint of obtaining high emission intensity. If M ^a contains at least one of Ca and Sr, the total molar ratio of Ca and Sr contained in the ^{M a} is, for example, 85 mol% or more, preferably at least 90 mol%.
The M ^b, from the viewpoint of stability of the crystal structure, preferably contains at least Li. If M ^b contains Li, the molar ratio of Li contained in the ^{M b} is, for example, 80 mol% or more, preferably at least 90 mol%.

  V, w, x, y and z in the formula (I) are not particularly limited as long as they satisfy the numerical ranges. v is preferably from 0.80 to 1.05, more preferably from 0.90 to 1.03, from the viewpoint of the stability of the crystal structure. x is an activation amount of at least one element selected from the group consisting of Eu, Ce, Tb, and Mn, and may be appropriately selected so that desired characteristics can be achieved. More preferably, x satisfies 0.001 <x ≦ 0.020, and more preferably satisfies 0.002 ≦ x ≦ 0.015.

The fired product includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg (M ^a element) and at least one element selected from the group consisting of Li, Na and K (M ^b Element), at least one element selected from the group consisting of Eu, Ce, Tb, and Mn ( ^Mc element), Al, and N, and optionally including Si. The raw material mixture obtained by mixing the raw materials can be obtained, for example, by firing in an atmosphere containing nitrogen gas having a temperature of 1000 ° C. to 1300 ° C. and a pressure of 0.2 MPa to 200 MPa.
By firing the raw material mixture at a predetermined temperature in a pressurized atmosphere containing nitrogen gas, a fired product used for a nitride phosphor having a desired composition and excellent emission intensity can be efficiently produced.

  The raw material mixture used for the fired product includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg, at least one element selected from the group consisting of Li, Na and K, and Eu. If it is possible to obtain a fired product having a composition containing at least one element selected from the group consisting of Ce, Tb and Mn, Al and N, and optionally containing Si, The material contained is not particularly limited. For example, the raw material mixture includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg, at least one element selected from the group consisting of Li, Na and K, and Eu, Ce, Selected from the group consisting of a single element of a metal element comprising a composition containing at least one element selected from the group consisting of Tb and Mn, Al and N, and including Si, if necessary, and those metal compounds Can be included. Examples of such metal compounds include hydrides, nitrides, fluorides, oxides, carbonates, chlorides, and the like, and are composed of hydrides, nitrides, and fluorides from the viewpoint of improving the light emission characteristics. It is preferably at least one selected from the group. When the raw material mixture contains an oxide, carbonate, chloride, or the like as a metal compound, the content thereof is preferably 5% by mass or less, more preferably 1% by mass or less in the raw material mixture. When these contents exceed a predetermined value, defects tend to occur in the crystal, and there is a possibility that the emission intensity is lowered and the half width of the emission spectrum is increased.

  The raw material mixture includes a metal compound containing a metal element selected from the group consisting of Ca, Sr, Ba and Mg, a metal compound containing a metal element selected from the group consisting of Li, Na and K, a metal compound containing Al, and It is preferable to contain at least one metal compound selected from the group consisting of metal compounds containing Eu. Moreover, the raw material mixture may contain the metal compound containing Si as needed.

Ca, Sr, metal compounds containing a metal element selected from the group consisting of Ba and Mg (M ^a element in the formula (I)) (hereinafter, also referred to as "first metal compound") Specific examples of, SrN ₂ , SrN, Sr ₃ N ₂ , SrH ₂ , SrF ₂ , Ca ₃ N ₂ , CaH ₂ , CaF _{2 and the} like, and at least one selected from the group consisting of these is preferable.

  The first metal compound preferably contains at least one of Ca and Sr. When the first metal compound contains Sr, a part of Sr may be substituted with Ca, Mg, Ba or the like. When the first metal compound contains Ca, a part of Ca may be substituted with Sr, Mg, Ba or the like. Thereby, the emission peak wavelength of the nitride phosphor can be adjusted. When the first metal compound contains Ca, it may further contain Li, Na, K, B, Al, or the like.

  The first metal compound is preferably a simple substance, but compounds such as an imide compound and an amide compound can also be used. The first metal compound may be used alone or in combination of two or more.

Li, metal compounds containing (M ^b element in the formula (I)) metallic element selected from the group consisting of Na and K (hereinafter, also referred to as "second metal compound") preferably contains at least Li More preferably, it is at least one of a nitride and a hydride of Li. When the second metal compound contains Li, a part of Li may be substituted with Na, K, or the like, and may contain other metal elements constituting the nitride phosphor.
Specific examples of the second metal compound containing Li include Li ₃ N, LiN ₃ , LiH, LiAlH _{4 and the} like, and at least one selected from the group consisting of these is preferable. The second metal compound may be used alone or in combination of two or more.

The metal compound containing Al (hereinafter also referred to as “third metal compound”) may be a metal compound containing substantially only Al as a metal element, and a part of Al is a group 13 element of Ga and It may be a metal compound substituted with a metal element selected from the group consisting of In and the fourth-period transition elements V, Cr, Co, etc., and constitutes a nitride phosphor such as Li in addition to Al It may be a metal compound containing other metal elements.
Specific examples of the third metal compound include AlN, AlH ₃ , AlF ₃ , and LiAlH _4, and at least one selected from the group consisting of these is preferable.
The third metal compound may be used alone or in combination of two or more.
When Si is included in a part of Al in the composition of the fired product, it is preferable to use a metal compound containing Si as a metal element. Examples of the metal compound containing Si include SiO ₂ , Si ₃ N ₄ , SiC, SiCl _{4 and the} like, and at least one selected from the group consisting of these can be used. The metal compound containing Si may be used alone or in combination of two or more.

Eu, Ce, metallic element selected from the group consisting of Tb and Mn metal compound containing (formula (M ^c elements in I)) (hereinafter, also referred to as "fourth metal compounds"), Eu as an activator , Ce, Tb and Mn.
When the fourth metal compound is Eu, a part of Eu is substituted with Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc. Also good. By substituting a part of Eu with another element, the other element is considered to act as a co-activator, for example. The light emission characteristics can be adjusted by co-activating the nitride phosphor. When using a mixture containing Eu as a nitride phosphor, the compounding ratio can be changed as desired. Europium mainly has bivalent and trivalent energy levels, but the fired product used for the nitride phosphor according to the present embodiment uses at least Eu ²⁺ as an activator.

Specific examples of the fourth metal compound include Eu ₂ O ₃ , EuN, EuF _{3 and the} like, and it is preferable to use at least one selected from the group consisting of these. The fired product used in the manufacturing method of the present embodiment contains divalent Eu as the center of light emission, but divalent Eu is easily oxidized, and a raw material mixture is formed using a metal compound containing trivalent Eu. Can do.

  In addition to the metal element simple substance and the metal compound, the raw material mixture may contain other metal elements other than those as required. Other metal elements can usually constitute the raw material mixture as oxides, hydroxides, etc., but are not limited thereto, simple metals, nitrides, imides, amides, other inorganic salts, etc. It may also be in a state of being previously contained in the raw material mixture described above.

  The raw material mixture may contain a flux. Since the raw material mixture contains a flux, the reaction between the raw materials is further promoted, and furthermore, the solid phase reaction proceeds more uniformly, so that the particle size is large, and it is used to obtain a nitride phosphor having excellent light emission characteristics. A fired product can be produced. This is considered to be because, for example, the heat treatment for obtaining the fired product is performed at 1000 ° C. or more and 1300 ° C. or less, and this temperature is substantially the same as the liquid phase formation temperature of a halide or the like as a flux. As the halide, rare earth metals, alkaline earth metals, alkali metal chlorides, fluorides, and the like can be used. As a flux, it can also add as a compound which becomes the target object composition of the baked product which can obtain the element ratio of a cation. Moreover, a flux can also be added in the form which adds a flux further to the raw material mixture which mixed each raw material so that it may become the target composition of the baked product obtained.

  When the raw material mixture contains a flux, the component of the flux promotes the reactivity between the raw materials in the raw material mixture, but if it is too much, it will lead to a decrease in the emission intensity of the phosphor using the obtained fired product, so its content Is, for example, preferably 10% by mass or less, more preferably 5% by mass or less in the raw material mixture.

Next, the manufacturing method of the baked product having the composition of Sr _0.993 Eu _0.007 LiAl ₃ N ₄ as the design composition among the baked products having the composition represented by the general formula (I) will be specifically described. However, the manufacturing method of the baked product used for the nitride phosphor is not limited to this.

As a metal compound constituting the raw material mixture, powders of SrN _u (equivalent to u = 2/3, a mixture of Sr ₂ N and SrN), LiAlH ₄ , AlN, EuF ₃ were used, and these were used as Sr: Li: Eu: Al. Are weighed in a glove box in an inert atmosphere so that the ratio is 0.9925: 1.2,000: 0.0075: 3.0000, and then mixed to obtain a raw material mixture. Here, Li is likely to be scattered during firing, so it is blended more than the target composition. In addition, this embodiment is not limited to this composition ratio. When using a metal compound containing fluorine as a raw material, the content of fluorine in the fired product is preferably 5% by mass or less. This is because if the fluorine content is larger than 5% by mass, pulverization is required after calcination, and the pulverization deteriorates the particle shape of the baked product.

  The raw material mixture is fired in a nitrogen atmosphere. For the firing, for example, a gas pressure electric furnace can be used. The firing temperature can be in the range of 1000 ° C. to 1400 ° C., preferably 1000 ° C. to 1300 ° C., more preferably 1100 ° C. to 1300 ° C. This is because if the firing temperature is low, the target phosphor compound is difficult to be formed, and if the firing temperature is high, the phosphor compound is decomposed and the light emission characteristics are impaired.

In addition, firing is performed in two stages (multi-stage firing) in which the first stage firing is performed at 800 ° C. or more and 1000 ° C. or less, and the temperature is gradually raised and the second stage firing is performed at 1000 ° C. or more and 1400 ° C. or less. You can also For firing the raw material mixture, a carbon material such as graphite, a boron nitride (BN) material, an alumina (Al ₂ O ₃ ), a crucible made of W, Mo material, a boat, or the like can be used.

  The firing atmosphere may be an atmosphere containing nitrogen gas, and may be an atmosphere containing at least one selected from the group consisting of hydrogen, argon, carbon dioxide, carbon monoxide, ammonia and the like in addition to nitrogen gas. . The ratio of nitrogen gas in the firing atmosphere is preferably 70% by volume or more, and more preferably 80% by volume or more.

  Firing is performed in a pressurized atmosphere of 0.2 MPa to 200 MPa. The target nitride phosphor is easily decomposed as the temperature becomes higher. However, by using a pressurized atmosphere, decomposition can be suppressed and more excellent light emission characteristics can be achieved. The pressurized atmosphere is preferably 0.2 MPa or more and 1.0 MPa or less, more preferably 0.8 MPa or more and 1.0 MPa or less as a gauge pressure. By increasing the pressure of the atmospheric gas during firing, decomposition of the phosphor compound during firing can be suppressed, and a phosphor having high characteristics can be obtained.

  The firing time may be appropriately selected according to the firing temperature, gas pressure, and the like. The firing time is, for example, 0.5 hours or more and 20 hours or less, and preferably 1 hour or more and 10 hours or less.

By firing, a fired product having a composition represented by Sr _0.993 Eu _0.007 LiAl ₃ N ₄ can be obtained. However, this composition is a theoretical composition estimated from the blending ratio of the raw material mixture, and the coefficients of each element and components such as F that are partly scattered during firing are excluded from the composition formula. As described above, the actual composition contains a certain amount of oxygen due to oxygen derived from raw materials and the like and oxidation generated in the process. Moreover, a certain amount of fluorine is contained by using a fluoride effective as a flux component as a raw material. Since decomposition, scattering, and the like occur during firing, the composition of the charge may have less Sr, Eu, Li than the theoretical composition when the charge composition ratio of Al is 3. Moreover, the composition of the target baked product can be changed by changing the blending ratio of each raw material.

  Moreover, the manufacturing method of a baked product is not limited to the manufacturing method mentioned above. For example, each elemental metal element is weighed to a predetermined composition ratio and then melted to form an alloy, and then the alloy is pulverized and then subjected to a gas pressure sintering furnace in a nitrogen gas atmosphere, hot isotropy, etc. You may manufacture the baked material used as the target composition by the HIP furnace etc. using the pressurization method (Hot Isostatic Pressing: HIP).

  The fired product preferably has a structure with high crystallinity at least in part. For example, a glass body (amorphous) has an irregular structure and low crystallinity. Therefore, if the reaction conditions in the production process cannot be controlled so as to be strictly uniform, chromaticity unevenness tends to occur. The fired product used in the method according to the present embodiment is preferably a powder or a granule having a structure with high crystallinity at least partially. A fired product having a structure with high crystallinity at least in part tends to be easily manufactured and processed. In addition, a nitride phosphor manufactured using a fired product having a structure with high crystallinity at least in part is easy to uniformly disperse in a resin. Can be easily prepared. Specifically, the fired product used for the nitride phosphor has a structure in which, for example, 50% by mass or more, more preferably 80% by mass or more has crystallinity. This indicates the ratio of the crystal phase having the light emitting property of the nitride phosphor manufactured using the fired product. If the fired product has a crystal phase of 50% by mass or more, light emission that can withstand practical use is obtained. Since the obtained nitride fluorescent substance can be manufactured, it is preferable. Therefore, it is possible to produce a nitride phosphor that has a higher emission intensity as the crystal phase of the fired product increases. Thereby, the light emission luminance of the nitride phosphor can be further increased and can be easily processed.

[Step of heat-treating the fired product]
The method for manufacturing a nitride phosphor according to an embodiment of the present invention includes bringing the fired product and a fluorine-containing material into contact with each other and performing a heat treatment at 200 ° C. or more and 500 ° C. or less. The fired product mainly constitutes a phosphor core of a nitride phosphor.

  The nitride phosphor manufactured by the method according to the present embodiment contains fluorine on or near the surface of the fired product by bringing the fired product into contact with the fluorine-containing material and performing a heat treatment at 200 ° C. or more and 500 ° C. or less. It is presumed that a compound is formed and this fluorine-containing compound is a protective film. By using such a nitride phosphor, it is possible to manufacture a light-emitting device that has little change in chromaticity and excellent durability even in an environment where the temperature and humidity are relatively high.

The fluorine-containing substance is not particularly limited as long as it contains fluorine, and examples thereof include fluorine gas (F ₂ ) and a fluorine compound. Examples of the fluorine compound include CF ₄ , CHF ₃ , NH ₄ HF ₂ , NH ₄ F, SiF ₄ , KrF ₂ , XeF ₂ , and NF ₃ .
The fluorine-containing material is at least one selected from the group consisting of F ₂ , CHF ₃ , CF ₄ , NH ₄ F ₂ , NH ₄ F, SiF ₄ , KrF ₂ , XeF ₂ , XeF ₄ , and NF _3. It is preferable.
More preferably, the fluorine-containing substance is fluorine gas (F ₂ ) or ammonium fluoride (NH ₄ F).

  The temperature of the environment in which the fired product is brought into contact with the fluorine-containing substance in a solid or liquid state at room temperature may be a temperature lower than the heat treatment temperature from room temperature (20 ° C. ± 5 ° C.), or may be a heat treatment temperature. Specifically, the temperature may be 20 ° C. or higher and lower than 200 ° C., or 20 ° C. or higher and 500 ° C. or lower. When the temperature of the environment in which the fired product is brought into contact with the fluorine-containing material in a solid state at room temperature is 20 ° C. or more and less than 200 ° C., the fired product is contacted with the fluorine-containing material, and then heat treatment is performed at 200 ° C. or more and 500 ° C. or less. To do.

  When the fluorine-containing material is in a solid state or a liquid state at room temperature, a fluorine-containing material of 1% by mass to 10% by mass with respect to 100% by mass of the total amount of the calcined product and the fluorine-containing material is calcined It is preferable to make it contact. The fluorine-containing material to be brought into contact with the fired product is preferably 2% by mass or more and 8% by mass or less, more preferably 3% by mass or more and 7% by mass or less with respect to 100% by mass of the total amount of the calcined product and the fluorine-containing material. It is. Thereby, it is estimated that the layer of the compound containing fluorine is easily formed on or near the surface of the fired product. In the nitride phosphor of this embodiment, this layer functions as a protective film, so that when the light emitting device is provided, the inside of the nitride phosphor is less affected by the external environment and improves the durability of the light emitting device. can do.

When the fluorine-containing substance is a gas, the fired product may be placed in contact with the atmosphere containing the fluorine-containing substance. When the fluorine-containing material is a gas, the fired product is placed in an atmosphere containing the fluorine-containing material, and the fired product is heat treated at 200 ° C. or more and 500 ° C. or less in the atmosphere containing the fluorine-containing material. Fluorine-containing material is a F _{2 (fluorine} gas), when heat-treating the calcined product at 200 ° C. or higher 500 ° C. or less in an atmosphere containing F ₂ is F ₂ concentration in the atmosphere is preferably 2 vol% or more It is 25 volume% or less, More preferably, it is 5 volume% or more and 20 volume% or less. If the F ₂ concentration in the atmosphere is not more than a predetermined amount, the desired durability may not be obtained. On the other hand, if the F ₂ concentration is a predetermined amount or more, the emission intensity may be greatly reduced by fluorination of the phosphor matrix.

  The heat treatment is preferably performed in an inert gas atmosphere. The inert gas atmosphere means an atmosphere containing argon, helium, nitrogen or the like as a main component in the atmosphere. The inert gas atmosphere may contain oxygen as an unavoidable impurity. Here, an inert gas atmosphere is used if the concentration of oxygen contained in the atmosphere is 15% by volume or less. The concentration of oxygen in the inert gas atmosphere is preferably 10% by volume or less, more preferably 5% by volume or less, and still more preferably 1% by volume or less. This is because if the oxygen concentration is a predetermined value or more, the phosphor particles may be excessively oxidized. When the fluorine-containing substance is a gas, the heat treatment is preferably performed in an atmosphere containing an inert gas and a fluorine-containing substance in consideration of safety, rather than in an atmosphere containing the fluorine-containing substance alone.

The temperature at which the fired product and the fluorine-containing substance are heat-treated is 200 ° C. or more and 500 ° C. or less. The temperature for the heat treatment is more preferably 250 ° C. or higher and 450 ° C. or lower, still more preferably 250 ° C. or higher and 400 ° C. or lower, and still more preferably 250 ° C. or higher and 350 ° C. or lower.
When the heat treatment temperature is lower than the predetermined temperature, a compound containing fluorine is hardly formed on the surface of the fired product or in the vicinity of the surface, and a durable nitride phosphor cannot be manufactured. On the other hand, if the heat treatment temperature exceeds a predetermined temperature, it is considered that the crystal structure of the fired product is easily destroyed, so that a highly durable nitride phosphor cannot be manufactured.

  The time for performing the heat treatment is not particularly limited, but is preferably 1 hour or longer and 10 hours or shorter, more preferably 2 hours or longer and 8 hours or shorter. If the time for performing the heat treatment is 1 hour or more and 10 hours or less, the layer of the compound containing fluorine is formed on or near the surface of the fired product by contacting the fired product with the fluorine-containing substance and performing the heat treatment. It is presumed that this layer functions as a protective film, so that durability when a light emitting device is obtained can be improved.

[Post-processing process]
The method for manufacturing a nitride phosphor according to the present embodiment may include a post-processing step of performing a crushing process, a pulverizing process, a classification process, and the like of the obtained nitride phosphor after the heat treatment.

(Nitride phosphor)
The nitride phosphor according to the embodiment of the present invention includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and at least one type selected from the group consisting of Li, Na and K. On the surface of the phosphor core having a composition containing an element, at least one element selected from the group consisting of Eu, Ce, Tb and Mn, Al and N, and optionally containing Si. It has a layer of a compound containing fluorine. The nitride phosphor of this embodiment may contain Si in a part of Al, may contain O due to oxidation of the surface, a part of N may be replaced by O, and one of N The part may be replaced with F, and a part of N may be replaced with both O and F.
The nitride phosphor of the present embodiment is preferably manufactured by the manufacturing method according to the embodiment of the present invention. The nitride phosphor of the present embodiment has the above-mentioned composition, preferably a contact between a fired product having a composition represented by the general formula (I) and a fluorine-containing substance, and a temperature of 200 ° C. or more and 500 ° C. or less. As a result of the heat treatment, a compound layer containing fluorine is formed on the surface of the fired product or a portion close to the surface. The fluorine-containing compound layer serves as a protective film, and the inside of the nitride phosphor is hardly affected by the external environment. The nitride phosphor of this embodiment forms a crystal structure of the nitride phosphor with carbon dioxide, moisture, etc. even in an environment where the temperature and humidity are relatively high due to the fluorine-containing compound layer present on the surface. It becomes difficult to react with the element to be performed, and is excellent in durability. Therefore, the light emitting device using the nitride phosphor according to the embodiment of the present invention is excellent in durability even in an environment where the temperature and humidity are relatively high, and can reduce the change in chromaticity.

The nitride phosphor of the present embodiment has a phosphor core having a composition represented by the following general formula (I) and a fluorine-containing compound layer not represented by the following general formula (I). Have. In the composition represented by the following general formula (I), a part of N may be replaced by O, a part of N may be replaced by F, or a part of N may be O due to surface oxidation. And F may be replaced.
_{^{M a v M b w M c}} x Al 3-y Si y N z (I)
(In the formula, M ^a is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M ^b is at least one type selected from the group consisting of Li, Na and K. M ^c is at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and v, w, x, y and z are 0.80 ≦ v ≦ 1. 05, 0.80 ≦ w ≦ 1.05, 0.001 <x ≦ 0.1, 0 ≦ y ≦ 0.5, 3.0 ≦ z ≦ 5.0.)

In formula (I), M ^a preferably contains at least one of Ca and Sr from the viewpoint of obtaining high emission intensity. If M ^a contains at least one of Ca and Sr, the total molar ratio of Ca and Sr contained in the ^{M a} is, for example, 85 mol% or more, preferably 90 mol%.
The M ^b, from the viewpoint of crystal structure stability, preferably contains at least Li. If M ^b contains Li, the molar ratio of Li contained in the ^{M b} is, for example, 80 mol% or more, preferably 90 mol%.

  V, w, x, y and z in the formula (I) are not particularly limited as long as they satisfy the numerical ranges. From the viewpoint of crystal structure stability, v is preferably 0.80 or more and 1.05 or less, and more preferably 0.90 or more and 1.03 or less. x is an activation amount of at least one element selected from the group consisting of Eu, Ce, Tb, and Mn, and may be appropriately selected so that desired characteristics can be achieved. x preferably satisfies 0.001 <x ≦ 0.020, and more preferably satisfies 0.002 ≦ x ≦ 0.015.

In the nitride phosphor of the present embodiment, the content of fluorine (F) in the nitride phosphor is preferably 1.0% by mass to 10.0% by mass, more preferably 2.0% by mass to 8%. 0.0 mass% or less, more preferably 2.5 mass% or more and less than 7.5 mass%.
In the nitride phosphor of this embodiment, a layer of a compound containing fluorine exists on the surface of the phosphor core or a portion close to the surface. The nitride phosphor of the present embodiment has not only fluorine in the compound layer containing fluorine present on or near the surface of the nitride phosphor, but also fluorine in the crystal structure of the nitride phosphor core. There is a possibility that there exists. The fluorine existing in the crystal structure of the nitride phosphor core is, for example, from oxygen mixed by oxidation of the nitride phosphor and Ca, Sr, Ba and Mg contained in the crystal structure of the nitride phosphor. with at least one element (M ^a element) and Al element selected from the group consisting, sometimes constituting M ^a element, and Al, and oxygen (O), in a compound containing a fluorine (F).

The nitride phosphor of the present embodiment has a fluorine-containing compound layer on the surface of the phosphor core or a portion close to the surface. The fluorine-containing compound layer includes the first layer and the first layer. It is preferable to have the 2nd layer from which a composition differs.
The nitride phosphor of the present embodiment has the above composition, preferably a fired product having a composition represented by the general formula (I) and a fluorine-containing substance are brought into contact with each other, and are 200 ° C. or more and 500 ° C. or less. By performing heat treatment at a temperature, a layer of a compound containing fluorine is formed on or near the surface of the fired product.
In the nitride phosphor of the present embodiment, the first layer and the second layer, which are layers of fluorine-containing compounds, are embedded in an epoxy resin, as will be described in Examples below. After the epoxy resin is cured, the nitride phosphor is cut so as to expose a cross section, and the cross section can be confirmed by observing with a scanning electron microscope (SEM). As shown in FIG. 7 described in the examples described later, in the SEM photograph of the reflected electron image of the cross section of the nitride phosphor, the phosphor core and the surface of the phosphor core constituting the nitride phosphor Separately, two layers having a contrast difference in contrast can be confirmed.

In the nitride phosphor of the present embodiment, the first layer of the fluorine-containing compound layer includes at least one element selected from the group consisting of Ca, Sr, Ba, and Mg, and fluorine. This layer preferably contains at least one element selected from the group consisting of Ca, Sr, Ba and Mg, Al and fluorine.
In the nitride phosphor of the present embodiment, the mechanism by which the first layer and the second layer are formed is not clear, but has the above composition, preferably the composition represented by the general formula (I). From the group consisting of Ca, Sr, Ba, and Mg constituting the skeleton of the crystal structure of the nitride phosphor by bringing the fired product into contact with the fluorine-containing substance and heat-treating it at a temperature of 200 ° C. or more and 500 ° C. or less. It is considered that the first layer containing a stable fluoride is formed on the surface of the nitride phosphor by reacting at least one element selected with fluorine. Further, by the heat treatment, the state of oxidation of the surface of the nitride phosphor and the state of the crystal structure constituting the nitride phosphor, for example, the firing that constitutes the nitride phosphor depending on the presence and amount of lattice defects, etc. Fluorine in the fluorine-containing material brought into contact with the substance reacts in the crystal structure of the nitride phosphor, and contains at least one element selected from the group consisting of Ca, Sr, Ba and Mg, Al and fluorine It is believed that a second layer is formed.
The second layer is an element constituting the crystal structure of the nitride phosphor in addition to at least one element selected from the group consisting of Ca, Sr, Ba and Mg, Al and fluorine (F). Nitrogen (N) may be included.

The nitride phosphor of the present embodiment preferably has the first layer on the surface and the second layer on the inner side of the first layer.
The nitride phosphor of the present embodiment has the above composition, preferably a fired product having a composition represented by the general formula (I) and a fluorine-containing substance are brought into contact with each other, and are 200 ° C. or more and 500 ° C. or less. By performing heat treatment at a temperature, a first layer containing fluoride is formed on the surface side, and a second layer is formed inside the first layer.
The nitride phosphor of the present embodiment is at least one selected from the group consisting of Ca, Sr, Ba, and Mg that forms a skeleton of the crystal structure of the nitride phosphor on the surface side that is an interface in contact with air. It is preferable to have the 1st layer containing the fluoride which has a stable structure containing these elements and fluorine. The nitride phosphor of this embodiment is excellent in durability even in an environment where the temperature and humidity are relatively high because the first layer containing a fluoride having a stable structure is formed on the surface.
The nitride phosphor of the present embodiment has a second layer having a composition different from that of the first layer on the inner side of the first layer formed on the surface side, and the second layer is nitrided Preferably, the phosphor is formed of a compound containing Al and fluorine, at least one element selected from the group consisting of Ca, Sr, Ba, and Mg that forms the skeleton of the crystalline structure of the phosphor. The nitride phosphor of the present embodiment has a second layer inside the first layer, and this second layer has a composition that also includes Al constituting the crystal structure of the nitride phosphor. By including the compound, the second layer becomes a bonding layer between the first layer containing fluoride on the surface and the crystal structure constituting the nitride phosphor, and the first layer on the surface of the nitride phosphor. Are considered to be more firmly coupled.
The nitride phosphor of the present embodiment has a stable first layer on the surface side, and the inside of the nitride phosphor is externally provided by having the second layer inside the first layer. It is less affected by the environment and has excellent durability even in environments with relatively high temperatures and humidity.

For example, when the nitride phosphor of the present embodiment is manufactured using a fired product having a composition of Sr _0.993 Eu _0.007 LiAl ₃ N ₄ as a design composition, the layer of the compound containing fluorine is It is preferably formed of a compound containing Sr element, which is an element constituting the crystal structure of the nitride phosphor, and fluorine.
Further, when a fired product having a composition of Sr _0.993 Eu _0.007 LiAl ₃ N ₄ is used as a design composition, the nitride phosphor of the present embodiment has an Sr element and fluorine ( F) and a compound containing Sr element, fluorine (F), and Al element constituting the crystal structure of the nitride phosphor as the second layer. It is preferable. The second layer may contain a compound containing N element constituting the crystal structure of the nitride phosphor in addition to Sr element, Al element, and F element.

The thickness of the fluorine-containing compound layer of the phosphor according to this embodiment is preferably 0.05 μm or more and 0.8 μm or less, and more preferably 0.05 μm or more and 0.6 μm or less.
In the case where the fluorine-containing compound layer of the nitride phosphor has the first layer and the second layer, the total thickness of the first layer and the second layer is 0.05 μm or more and 0.0. It is preferable that it is 8 micrometers or less.
When the thickness of the fluorine-containing compound layer of the nitride phosphor is less than 0.05 μm, the thickness is small, so even if a fluorine-containing compound layer exists, the function as a protective film is small. In addition, it is easily affected by the external environment such as temperature and humidity, and the durability may be lower than that of a nitride phosphor having a fluorine-containing compound layer thickness of 0.05 μm or more.
When the thickness of the fluorine-containing compound layer of the nitride phosphor according to the present embodiment exceeds 0.8 μm, the thickness of the fluorine-containing compound layer increases, and light reflection and the like increase. When a phosphor is used for a light emitting device, a desired light emission intensity may not be obtained.
In the nitride phosphor according to the present embodiment, the thickness of the fluorine-containing compound layer is determined by embedding the nitride phosphor in an epoxy resin and curing the epoxy resin, as described in the examples described later. Cutting is performed so that the cross section of the phosphor is exposed, the cross section is observed using a scanning electron microscope (SEM), and the thickness of the compound layer containing fluorine can be measured from the obtained image. . As shown in FIG. 7 described in Examples described later, in the SEM photograph of the reflected electron image of the cross section of the nitride phosphor, the compound layer containing fluorine has an average thickness of about 0.1 μm.
In the nitride phosphor according to this embodiment, the average thickness of the fluorine-containing compound layer is 0.05 μm or more and 0.3 μm or less.

  The nitride phosphor of the present embodiment absorbs light in the wavelength range of 400 nm to 570 nm, which is a short wavelength side region from ultraviolet to visible light, and emits fluorescence having an emission peak wavelength in the wavelength range of 630 nm to 670 nm. It is preferable that

  The emission spectrum of the nitride phosphor has an emission peak wavelength in the range of 630 nm to 670 nm, preferably in the range of 640 nm to 660 nm. The half width of the emission spectrum is, for example, 65 nm or less, and preferably 60 nm or less. The lower limit of the full width at half maximum is, for example, 45 nm or more.

In the nitride phosphor of the present embodiment, europium (Eu), Ce, Tb, or Group 7 Mn, which is a rare earth, becomes the emission center. However, the emission center of the nitride phosphor of the present embodiment is not limited to Eu, Ce, Tb, or Mn. For example, when Eu is included, other rare earth metals or alkaline earth metals are included in part of Eu. It is also possible to use a material co-activated with Eu. For example, Eu ^2+, which is a divalent rare earth ion, exists stably by selecting an appropriate base material and emits light.

  The average particle diameter of the nitride phosphor of the present embodiment is, for example, 4.0 μm or more, preferably 4.5 μm or more, and more preferably 5.0 μm or more from the viewpoint of light emission intensity. Moreover, an average particle diameter is 20 micrometers or less, for example, and 18 micrometers or less are preferable. The average particle size of the nitride phosphor of the present embodiment is an average particle size including a layer of a compound containing fluorine.

  By setting the average particle size to a predetermined value or more, the absorption rate and emission intensity of excitation light to the nitride phosphor tend to be higher. Thus, the luminous efficiency of a light-emitting device becomes high by containing the nitride fluorescent substance excellent in the light emission characteristic in the light-emitting device mentioned later. Moreover, workability | operativity in the manufacturing process of a light-emitting device can be improved by making an average particle diameter below a predetermined value.

  In this specification, the average particle size of the nitride phosphor and the average particle size of the other phosphors are the volume average particle size, laser diffraction type particle size distribution measuring device (product name: MASTER SIZER (master sizer) 2000, MALVERN ( It is a particle diameter (median diameter) measured by Malvern).

(Light emitting device)
Next, a light emitting device using the nitride phosphor of the present embodiment as a component of the wavelength conversion member will be described.
A light-emitting device according to an embodiment of the present invention includes a nitride phosphor according to an embodiment of the present invention and an excitation light source.

  The excitation light source used in the light emitting device according to this embodiment is preferably an excitation light source that emits light in a wavelength range of 400 nm or more and 570 nm or less. By using an excitation light source in the wavelength range, a phosphor with high emission intensity can be provided. In particular, it is more preferable to use an excitation light source having a main emission peak wavelength in the range of 420 nm to 500 nm, and it is more preferable to use an excitation light source having a main emission peak wavelength in the range of 420 nm to 460 nm. By using the light emitting element having the emission peak wavelength as the excitation light source, it is possible to configure a light emitting device that emits mixed light of light from the light emitting element and fluorescence from the phosphor.

The half width of the emission spectrum of the light emitting element can be set to 30 nm or less, for example.
A semiconductor light emitting element is preferably used as the light emitting element. By using a semiconductor light emitting element as a light source, it is possible to obtain a stable light emitting device with high efficiency, high output linearity with respect to input, and strong against mechanical shock.
As the semiconductor light emitting element, for example, a semiconductor light emitting element using a nitride semiconductor (In _X Al _Y Ga _1- XYN, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) can be used.

  The light emitting device includes at least the nitride phosphor according to the present embodiment. The nitride phosphor has a composition represented by the formula (I), is excited by light in a wavelength range of 400 nm to 570 nm, has an emission peak wavelength in a wavelength range of 630 nm to 670 nm, and has a reflectance at 650 nm. The reflectance ratio at 460 nm is preferably 2 or more. The details of the nitride phosphor are as described above, and the preferred forms are also the same. The light emitting device preferably includes a first phosphor containing the nitride phosphor and a second phosphor.

  For example, the first phosphor can be contained in a sealing member that covers the excitation light source to form a light emitting device. In the light emitting device in which the excitation light source is covered with the sealing member containing the first phosphor, a part of the light emitted from the excitation light source is absorbed by the first phosphor and emitted as red light. By using an excitation light source that emits light in a wavelength range of 400 nm or more and 570 nm or less, emitted light can be used more effectively.

  The content of the first phosphor contained in the light emitting device is not particularly limited and can be appropriately selected according to the color desired to be finally obtained. For example, the content of the first phosphor can be 1% by mass or more and 50% by mass or less with respect to the resin, and is preferably 2% by mass or more and 30% by mass or less.

  The light emitting device may include a second phosphor having an emission peak wavelength different from that of the first phosphor. For example, the light emitting device can have a wide color reproduction range and high color rendering by appropriately including a light emitting element that emits blue light, and a first phosphor and a second phosphor that are excited by the light emitting element. .

Examples of the second phosphor include phosphors having a composition represented by any of the following formulas (IIa) to (IIi), and a composition represented by a formula selected from the group consisting of these: It is preferable to include at least one of phosphors having the same. For example, it is more preferable to include at least one phosphor having a composition represented by the formula (IIc), (IIe) or (IIi) in that a wide color reproduction range can be obtained. Moreover, it is more preferable that at least 1 sort (s) of the fluorescent substance which has a composition shown by Formula (IIa), (IId), (IIf) or (IIg) is included at the point from which a high color rendering property is acquired.
(Y, Gd, Tb, Lu) ₃ (Al, Ga) ₅ O ₁₂ : Ce (IIa)
(Ba, Sr, Ca) ₂ SiO ₄ : Eu (IIb)
Si _6-p Al _p O _p N _8-p : Eu (0 <p ≦ 4.2) (IIc)
(Ca, Sr) ₈ MgSi ₄ O ₁₆ (Cl, F, Br) ₂ : Eu (IId)
(Ba, Sr, Ca) Ga ₂ S ₄ : Eu (IIe)
(Ba, Sr, Ca) ₂ Si ₅ N ₈ : Eu (IIf)
(Sr, Ca) AlSiN ₃ : Eu (IIg)
_{K 2 (Si, Ge, Ti} ) F 6: Mn (IIh)
(Ba, Sr) MgAl ₁₀ O ₁₇ : Mn (IIi)

  The average particle diameter of the second phosphor is preferably 2 μm or more and 35 μm or less, and more preferably 5 μm or more and 30 μm or less. The emission intensity can be increased by setting the average particle size to a predetermined value or more. By setting the average particle size to a predetermined value or less, workability in the manufacturing process of the light emitting device can be improved.

  The content of the second phosphor can be, for example, from 1% by mass to 200% by mass with respect to the resin, and is preferably from 2% by mass to 180% by mass.

  The content ratio of the first phosphor and the second phosphor (first phosphor / second phosphor) can be, for example, 0.01 or more and 5.00 or less as a mass ratio. 05 or more and 3.00 or less are preferable.

  The first phosphor and the second phosphor (hereinafter, also simply referred to as “phosphor”) can form a sealing member that covers the light emitting element together with the resin. Examples of the resin constituting the sealing member include thermosetting resins such as silicone resins, epoxy resins, epoxy-modified silicone resins, and modified silicone resins.

  The total content of the phosphor in the sealing material can be, for example, 5% by mass to 300% by mass with respect to the resin, preferably 10% by mass to 250% by mass, and more preferably 15% by mass to 230% by mass. % Or less is more preferable, and 15% by mass or more and 200% by mass or less is more preferable. When the phosphor content in the sealing material is within the above range, the light emitted from the light emitting element can be wavelength-converted efficiently by the phosphor.

  The sealing member may further include a filler, a light diffusing material, and the like in addition to the resin and the phosphor. For example, by including a light diffusing material, the directivity from the light emitting element can be relaxed and the viewing angle can be increased. Examples of the filler include silica, titanium oxide, zinc oxide, zirconium oxide, and alumina. When a sealing member contains a filler, the content can be suitably selected according to the objective etc. The filler content can be, for example, 1% by mass or more and 20% by mass or less based on the resin.

  An example of the light emitting device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device according to this embodiment. This light-emitting device is an example of a surface-mounted light-emitting device.

  The light emitting device 100 includes a package having a recess formed by the lead electrodes 20 and 30 and the molded body 40, the light emitting element 10, and a fluorescent member 50 that covers the light emitting element 10. The light emitting element 10 is disposed in the recess of the package and is electrically connected to the pair of positive and negative lead electrodes 20, 30 provided in the molded body 40 by the conductive wire 60. The fluorescent member 50 is filled in the concave portion, covers the light emitting element 10, and seals the concave portion of the package. The fluorescent member 50 includes, for example, a phosphor 70 that converts the wavelength of light from the light emitting element 10 and a resin. Further, the phosphor 70 includes a first phosphor 71 and a second phosphor 72. A part of the pair of positive and negative lead electrodes 20 and 30 is exposed on the outer surface of the package. The light emitting device 100 emits light upon receiving power supply from the outside via the lead electrodes 20 and 30.

  The fluorescent member 50 includes a resin and a phosphor and is formed so as to cover the light emitting element 10 placed in the recess of the light emitting device 100.

  Hereinafter, the present invention will be specifically described by way of examples.

(Production of fired product)
A phosphor having a composition containing Sr, Li, Eu, Al, and N was manufactured.
Specifically, ^M _a v of the general formula _{^{(I) M b w M c}} x Al 3-y Si y N as the phosphor having a composition represented by _z, ^{M a} is Sr, ^{M b} is Li, M ^c was Eu, and SrN _u (equivalent to u = 2/3, a mixture of Sr ₂ N and SrN), SrF ₂ , LiAlH ₄ , AlN, and EuF ₃ were used as raw materials. In this example, y in the general formula (I) is 0. In a glove box in an inert gas atmosphere so that the molar ratio of the above-mentioned raw materials as the charged amount ratio is Sr: Li: Eu: Al = 0.9925: 1.2,000: 0.0075: 3.0000 After weighing, mixing was performed to obtain a raw material mixture. Wherein the weight ratio of SrN _u and SrF ₂ is 94: I was 6. In addition, Li (lithium) is likely to be scattered during firing, so it was blended more than the theoretical value. The crucible is filled with the raw material mixture, the gas pressure is 0.92 MPa (absolute pressure is 1.02 MPa), the temperature is 1100 ° C., and the heat treatment is performed for 3 hours in a nitrogen gas atmosphere, and Sr _0.9925 LiEu ₀ A fired product having a composition represented by _0.075 Al ₃ N ₄ was obtained. Thereafter, this fired product was dispersed and classified to obtain fired product 1.

Example 1
The fired product 1 contains fluorine gas (F ₂ ) and nitrogen gas (N ₂ ), has an atmosphere of fluorine gas concentration of 20% by volume, and nitrogen gas concentration of 80% by volume or more. Heat treatment was performed for 8 hours to obtain a nitride phosphor powder of Example 1.

(Comparative Example 1)
The fired product 1 was used as the nitride phosphor of Comparative Example 1.

(Example 2)
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the temperature was 250 ° C.

(Example 3)
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the fluorine gas concentration was 10% by volume.

Example 4
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the fluorine gas concentration was changed to 5% by volume.

(Example 5)
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the temperature was 350 ° C.

(Comparative Example 2)
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the temperature was 30 ° C.

(Comparative Example 3)
A nitride phosphor powder was obtained under the same conditions as in Example 1 except that the temperature was 150 ° C.

(Example 6)
The phosphor obtained in Comparative Example 2 was heat-treated in the atmosphere at a temperature of 300 ° C. and a treatment time of 10 hours to obtain a nitride phosphor powder.

(Example 7)
The phosphor obtained in Comparative Example 3 was heat-treated in the atmosphere at a temperature of 300 ° C. and a treatment time of 10 hours to obtain a nitride phosphor powder.

(Example 8)
Ammonium fluoride is added so that ammonium fluoride (NH ₄ F) is 5% by mass with respect to 100% by mass of the total amount of the fired product 1 and ammonium fluoride, and nitrogen gas (N ₂ ) is 90% by volume or more. Heat treatment was carried out in an atmosphere including a temperature of 200 ° C. and a treatment time of 2 hours to obtain a nitride phosphor powder.

Example 9
A nitride phosphor powder was obtained under the same conditions as in Example 8 except that the temperature was 300 ° C.

(Example 10)
A nitride phosphor powder was obtained under the same conditions as in Example 9 except that the atmosphere was air.

(Comparative Example 4)
A nitride phosphor powder was obtained under the same conditions as in Example 8 except that the temperature was 150 ° C.

<Evaluation>
(X-ray diffraction spectrum)
About the obtained nitride fluorescent substance, the X-ray-diffraction spectrum (XRD) was measured. The measurement was performed using CuKα rays using a sample horizontal multipurpose X-ray diffractometer (product name: Ultimate IV, Rigaku Corporation). An example of the obtained XRD pattern is shown in FIG. FIG. 2 shows the XRD patterns of the nitride phosphors of Comparative Examples 1 to 3, Example 1 and Example 5 in order from the top. As reference examples, the XRD patterns of the compounds represented by SrF ₂ and LiSrAlF ₆ are shown. Show.

(Luminescent characteristics)
The emission characteristics of the obtained nitride phosphor were measured. The emission characteristics of the nitride phosphor were measured with a spectrofluorometer (product name: QE-2000, manufactured by Otsuka Electronics Co., Ltd.) at a wavelength of excitation light of 450 nm. The energy (relative emission intensity:%) of the obtained emission spectrum was determined. The results are shown in Table 1. The relative light emission intensity was calculated with the nitride phosphor of Comparative Example 1 as 100%. The emission peak wavelength was 650 to 660 nm in each of Comparative Examples 1 to 4 and Examples 1 to 10. FIG. 3 shows emission spectra of relative emission intensities with respect to the wavelengths of the nitride phosphors of Comparative Example 1, Examples 1, 3 to 5, and 7.

(Composition analysis)
The obtained nitride phosphor was subjected to composition analysis by ICP emission analysis using an inductively coupled plasma emission analyzer (manufactured by Perkin Elmer (Perkin Elmer)). When the content of fluorine (F) is less than 1.0% by mass, a quantitative analysis is performed using an ion chromatograph (ICS-1500 manufactured by DIONEX) by ion chromatography, and the content of fluorine (F) is In the case of 1.0% by mass or more, quantitative analysis was performed using a double beam spectrophotometer (HITACHI U-2900) by the UV-VIS method. The content of fluorine element in the nitride phosphor was determined, and the results are shown in Table 1.

(Storage test)
A light emitting device was manufactured using the obtained nitride phosphor. A nitride material having a main wavelength of 451 nm is a sealing material dispersed in a silicone resin, using the nitride phosphor of each of the examples and comparative examples as a first phosphor and β sialon as a green phosphor as a second phosphor. A surface-mounted light-emitting device having a chromaticity (x, y) = (0.25, 0.22) vicinity was manufactured by sealing the semiconductor light-emitting element. The light emitting device was stored at a temperature of 85 ° C. and a relative humidity of 85% for 100 hours, and then the chromaticity x was measured and obtained as a change amount (absolute value) with respect to the chromaticity x before the storage test.

(SEM image-secondary electron image)
SEM photographs of secondary electron images of the nitride phosphors of Comparative Examples 1 and 3 and the nitride phosphors of Examples 1 and 5 were obtained using a scanning electron microscope (SEM). 4 is an SEM photograph of the nitride phosphor of Example 1, FIG. 5 is an SEM photograph of the nitride phosphor of Comparative Example 1, and FIG. 6 is an SEM of the nitride phosphor of Example 5. FIG. 8 is a SEM photograph of the nitride phosphor of Comparative Example 3.

(SEM image-reflected electron image)
The obtained nitride phosphor was embedded in an epoxy resin, and after the resin was cured, the nitride phosphor was cut so that a cross section of the nitride phosphor was exposed, the surface was polished with sandpaper, and then a cross section polisher (CP The surface was finished and a scanning electron microscope (SEM) was used to obtain SEM photographs of reflected electron images of cross sections of the nitride phosphors of Example 5 and Comparative Example 3. FIG. 7 is a SEM photograph of the reflected electron image of the cross section of the nitride phosphor of Example 5, and FIG. 9 is a SEM photograph of the reflected electron image of the cross section of the nitride phosphor of Comparative Example 3.

(Average particle size)
About the obtained nitride fluorescent substance, the volume average particle diameter (median diameter) measured with the laser diffraction type particle size distribution measuring apparatus (Product name: MASTER SIZER (master sizer) 2000, MALVERN (Malvern) company make) average particle diameter It was.

  Table 1 shows contact conditions and heat treatment conditions between the fired products of Examples and Comparative Examples and fluorine-containing materials. In Table 1, Comparative Examples 2 and 3, Examples 1 to 5, Comparative Example 4, and Examples 8 and 9 have common contact conditions and heat treatment conditions. In Examples 6 and 7, both the contact condition between the fired product and the fluorine-containing substance and another additional heat treatment were performed, and the conditions are shown in Table 1.

  Examples 1 to 5 are cases where the fired product was brought into contact with fluorine gas and heat-treated in an inert gas atmosphere containing fluorine gas. In Examples 6 and 7, the fired product and fluorine gas were brought into contact with each other and additionally heat-treated in the atmosphere. Examples 8 to 10 are cases where they were brought into contact with ammonium fluoride in a solid state at room temperature and then heat-treated in the atmosphere. In any of these Examples, as shown in Table 1, it was confirmed that the change in chromaticity x after storage was less in the above environment than in Comparative Examples 1 to 4, and the durability was improved.

As shown in the X-ray diffraction spectrum of FIG. 2, the compounds of Comparative Examples 1 to 3 and Examples 1 and 5 are all represented by Sr _0.9925 LiEu _0.075 Al ₃ N ₄ of Comparative Example 1. It was confirmed that it was a compound. In Example 1 and Example 5, when 2θ is in the vicinity of 25 ° to 27 °, the same peak as the peak represented by the compound represented by SrF ₂ or LiSrAlF ₆ appears, and from this result, fluorine element is included. It can be confirmed. In the light emitting device of the example, it is considered that the fluorine-containing compound layer formed on or near the surface of the fired product constituting the phosphor core of the nitride phosphor functions as a protective film. The change in chromaticity x is small and the durability is excellent.

  As shown in FIG. 3, the emission spectra of the relative emission intensities with respect to the wavelengths of the nitride phosphors of Examples 1, 3 to 5, and 7 have substantially the same emission intensity as that of the nitride phosphor of Comparative Example 1. In addition, since the peak shape of the emission spectrum of the example is almost the same as that of Comparative Example 1, the crystal structure is not changed by the heat treatment, and the crystal structure is presumed to be stable.

  The SEM photograph of the secondary electron image of the nitride phosphor of Example 1 shown in FIG. 4 and the SEM photograph of the secondary electron image of the nitride phosphor of Comparative Example 1 shown in FIG. 5 are two SEMs. It can be confirmed that there is no difference in the appearance of the nitride phosphor shown in the photograph.

The SEM photograph of the secondary electron image of the nitride phosphor of Example 5 shown in FIG. 6 has little difference in appearance from the SEM photograph of the nitride phosphor of Example 1 shown in FIG.
As shown in the backscattered electron image of the nitride phosphor of Example 5 shown in FIG. 7, a layer containing a compound containing fluorine is formed on the surface of the nitride phosphor of Example 5. .
In the SEM photograph of the cross section of the nitride phosphor shown in FIG. 7, there is a difference in contrast between the surface of the phosphor core 3 constituting the nitride phosphor and the vicinity of the surface, in addition to the phosphor core 3. One layer can be confirmed. As a result of the composition analysis, the first layer 1 formed on the surface of the nitride phosphor is a layer formed of a compound containing Sr and F that form the crystal structure of the nitride phosphor, The second layer 2 existing inside the one layer 1 was a layer containing a compound containing Sr and Al contained in the crystal structure of the nitride phosphor and F. The compound constituting the second layer 2 contained N in addition to Sr, Al, and F.
The nitride phosphor shown in FIG. 7 functions as a protective film by the first layer 1 and the second layer 2 containing a compound containing fluorine, and the nitride phosphor is nitrided near the surface of the nitride phosphor. Alkaline earth metal elements (for example, elements selected from the group consisting of Ca, Sr, Ba and Mg) or alkali metal elements (for example, elements selected from the group consisting of Li, Na and K) constituting the phosphor ) Is difficult to react with carbon dioxide, moisture, etc., and the durability is considered to be improved.

  When the total thickness of the first layer 1 and the second layer 2 is determined from the SEM photograph of the electron reflection image of the cross section of the nitride phosphor shown in FIG. 7, the average thickness of the compound layer containing fluorine is 0. The thickness of the thinnest layer is about 0.05 μm, and the thickness of the thickest layer is about 0.6 μm to 0.7 μm.

As shown in Table 1, the nitride phosphor of Comparative Example 1 contains 0.6% by mass of fluorine element due to the influence of the fluorine compound contained in the raw material, but the fired product and the fluorine-containing material are brought into contact with each other. In addition, since no heat treatment was performed, the change in chromaticity x after storage in an environment where the temperature was 85 ° C. and the relative humidity was 85% was larger than that of the example, and the durability was not improved.
In the nitride phosphor of Comparative Example 2, the fired product and the fluorine-containing substance are brought into contact with each other, but since the heat treatment is not performed, a compound layer containing fluorine is not formed on or near the surface of the fired product. It is conceivable that the change in chromaticity x after storage in the above environment is larger than that in the example.
The nitride phosphors of Comparative Examples 3 and 4 are subjected to heat treatment by bringing the fired product into contact with the fluorine-containing material. However, since the temperature of the heat treatment is 150 ° C., which is lower than that of the example, protection of the compound containing fluorine It is considered that the film is not sufficiently formed. In the nitride phosphor of Comparative Example 3, it was confirmed by the reflected electron image of the cross section that a layer containing fluorine was not formed as will be described later.

The SEM photograph of the secondary electron image of the nitride phosphor of Comparative Example 3 shown in FIG. 8 is the SEM photograph of the nitride phosphor of Example 1 shown in FIG. 4, and the nitride of Comparative Example 1 shown in FIG. There is little difference in appearance from the SEM photograph of the product phosphor and the SEM photograph of the nitride phosphor of Example 5 shown in FIG.
However, as shown in the reflected electron image of the cross section of the nitride phosphor of Comparative Example 3 shown in FIG. 9, the surface of the nitride phosphor of Comparative Example 3 is close to or near the surface of the phosphor core 3. A layer containing a compound containing fluorine cannot be confirmed.
In Comparative Example 3 shown in FIG. 9, a nitride phosphor particle is different from the phosphor core 3 and includes elements constituting the nitride phosphor, for example, Sr and fluorine (F). Compound 5 was formed.
Further, as shown in FIG. 9, the nitride phosphor may contain an aluminum nitride compound 4 in addition to the phosphor core 3.
In FIG. 9, reference numeral 6 denotes a second compound having a structure different from that of the phosphor core 3 and containing Sr and fluorine (F) as a result of the composition analysis, and further containing Al and oxygen (O).

  From the results shown in Table 1, the nitride phosphor according to this embodiment maintains a high light emission intensity, and changes in chromaticity are suppressed even after storage in the above environment. Thus, since the nitride phosphor manufactured by the method according to the present embodiment is excellent in durability, a highly reliable light-emitting device can be provided by using this nitride phosphor.

  A highly durable nitride phosphor can be obtained by the manufacturing method of the present disclosure. The nitride phosphor of the present embodiment can be used for a light emitting device, and the light emitting device of the present embodiment can be suitably used as a light source for illumination. In particular, it can be suitably used for an illumination light source, an LED display, a backlight source for liquid crystal, a traffic light, an illumination switch, various sensors, various indicators, and the like that have extremely excellent light emission characteristics using a light emitting diode as an excitation light source.

  1: first layer, 2: second layer, 3: phosphor core, 4: AlN compound, 5: first compound, 6: second compound, 10: light emitting device, 40: molded product, 50: sealing member, 71: first phosphor, 72: second phosphor, 100: light emitting device.

Claims (14)

A group consisting of at least one element selected from the group consisting of Ca, Sr, Ba and Mg, at least one element selected from the group consisting of Li, Na and K, and Eu, Ce, Tb and Mn A method for producing a nitride phosphor having a composition containing at least one element selected from Al, Al, and N,
Preparing a fired product having the composition,
A method for producing a nitride phosphor, comprising: bringing the fired product into contact with a fluorine-containing substance and performing a heat treatment at a temperature of 200 ° C. to 500 ° C. The fluorine-containing material is at least one selected from the group consisting of F ₂ , CHF ₃ , CF ₄ , NH ₄ HF ₂ , NH ₄ F, SiF ₄ , KrF ₂ , XeF ₂ , XeF ₄ and NF _3. The method for producing a nitride phosphor according to claim 1.   The method for producing a nitride phosphor according to claim 1 or 2, wherein the heat treatment is performed in an inert gas atmosphere.   The method for producing a nitride phosphor according to claim 3, wherein the fluorine-containing substance is a gas, and the heat treatment is performed in an atmosphere containing the inert gas and the fluorine-containing substance.   The manufacturing method of the nitride fluorescent substance as described in any one of Claims 1-4 whose said fluorine-containing substance is fluorine gas.   The manufacturing method of the nitride fluorescent substance as described in any one of Claims 1-3 whose said fluorine-containing substance is ammonium fluoride. The method for producing a nitride phosphor according to any one of claims 1 to 6, wherein the fired product has a composition represented by the following general formula (I).
^{_{M a v M b w M c}} x Al 3-y Si y N z (I)
(In the formula, M ^a is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M ^b is at least one type selected from the group consisting of Li, Na and K. M ^c is at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and v, w, x, y and z are 0.80 ≦ v ≦ 1. 05, 0.80 ≦ w ≦ 1.05, 0.001 <x ≦ 0.1, 0 ≦ y ≦ 0.5, 3.0 ≦ z ≦ 5.0.)   A group consisting of at least one element selected from the group consisting of Ca, Sr, Ba and Mg, at least one element selected from the group consisting of Li, Na and K, and Eu, Ce, Tb and Mn A nitride phosphor having a layer of a compound containing fluorine on the surface of a phosphor core containing a composition containing at least one element selected from Al, N, and optionally containing Si. The nitride phosphor according to claim 8, wherein the phosphor core has a composition represented by the following general formula (I).
^{_{M a v M b w M c}} x Al 3-y Si y N z (I)
(In the formula, M ^a is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M ^b is at least one type selected from the group consisting of Li, Na and K. M ^c is at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and v, w, x, y and z are 0.80 ≦ v ≦ 1. 05, 0.80 ≦ w ≦ 1.05, 0.001 <x ≦ 0.1, 0 ≦ y ≦ 0.5, 3.0 ≦ z ≦ 5.0.)   The nitride phosphor according to claim 8 or 9, wherein the fluorine-containing compound layer has a first layer and a second layer having a composition different from that of the first layer.   The first layer includes at least one element selected from the group consisting of Ca, Sr, Ba and Mg and fluorine, and the second layer is selected from the group consisting of Ca, Sr, Ba and Mg The nitride phosphor according to claim 10, comprising at least one element selected from the group consisting of Al and fluorine.   The nitride phosphor according to claim 10 or 11, which has the first layer on the surface and the second layer on the inner side of the first layer.   13. The nitride phosphor according to claim 8, wherein the fluorine-containing compound layer has a thickness of 0.05 μm or more and 0.8 μm or less.   A light emitting device comprising the nitride phosphor according to claim 8 and an excitation light source.