JP7025673B2 - Nitride phosphor manufacturing method and nitride phosphor - Google Patents

Description

The present invention relates to a method for producing a nitride fluorophore and a nitride fluorophore.

Light emitting diodes (hereinafter referred to as "LEDs") and light emitting devices formed by combining phosphors are widely used in lighting devices, backlights of liquid crystal display devices, etc., and are becoming more widespread. I'm 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 (hereinafter, may be referred to as “SLAN phosphor”) that emits red light and has a composition represented by SrLiAl ₃ N ₄ : Eu. For example, Patent Document 1 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) Disclosed is an SLAN phosphor having a narrow half-price width of 70 nm or less and an emission peak wavelength of around 650 nm.

This SLAN phosphor is, 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 ). After weighing and mixing at a chemical quantitative ratio such that Eu is 0.4 mol%, put it in a rutsubo and bake it under atmospheric pressure in a mixed gas atmosphere of hydrogen and nitrogen at a temperature of 1000 ° C. and a firing time of 2 hours. It is manufactured by.

Japanese Patent Publication No. 2015-526532

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 is easily deteriorated by oxygen, heat, moisture and the like, and further improvement in the durability of the light emitting device using such an SLAN phosphor has been required.
Therefore, one embodiment of the present invention aims to provide a method for producing a nitride phosphor that can be a light emitting device having excellent durability, and a nitride phosphor.

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 comprises 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 a calcined product having the above composition is prepared. A method for producing a nitride phosphor, which comprises contacting the fired product with a fluorine-containing substance and heat-treating at a temperature of 200 ° C. or higher and 500 ° C. or lower.

A second embodiment of the present invention comprises 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 a 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 Si. It is a nitride phosphor having a layer of.

A 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 method for producing a nitride fluorescent substance having excellent durability and a nitride fluorescent substance.

FIG. 1 is a schematic cross-sectional view showing 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 with the compounds of Reference Examples (SrF ₂ , LiSrAlF ₆ ). FIG. 3 is a diagram showing emission spectra showing relative emission intensities with respect to wavelength for the nitride phosphors of Examples and Comparative Examples of the present invention. FIG. 4 is an SEM photograph of a secondary electron image of the nitride phosphor according to Example 1. FIG. 5 is an SEM photograph of a secondary electron image of the nitride phosphor according to Comparative Example 1. FIG. 6 is an SEM photograph of a secondary electron image of the nitride phosphor according to Example 5. FIG. 7 is an SEM photograph of a reflected electron image of a cross section 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, a method for producing a nitride phosphor according to the present disclosure, a nitride phosphor, and an embodiment of a light emitting device will be described. However, the embodiments shown below exemplify a method for producing a nitride fluorescent substance for embodying the technical idea of the present invention, and the present invention is the following method for producing a nitride fluorescent substance. Not limited to. The relationship between the color name and the chromaticity coordinate, the relationship between the wavelength range of light and the color name of monochromatic light, etc., follow JIS Z8110. Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.

(Manufacturing method of nitride phosphor)
The method for producing a nitride phosphor according to the embodiment of the present invention comprises at least one element selected from the group consisting of Ca, Sr, Ba and Mg and at least one 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, and Al and N. This includes preparing a fired product having the above, bringing the fired product into contact with a fluorine-containing substance, and heat-treating at a temperature of 200 ° C. or higher and 500 ° C. or lower.

[Process to prepare fired product]
The calcined product prepared in the production method of the present embodiment is at least one element selected from the group consisting of Ca, Sr, Ba and Mg and at least one selected from the group consisting of Li, Na and K. The composition is not particularly limited as long as it has a composition containing 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, O may be contained by oxidation of the surface, and a part of N may be replaced with 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 by oxidation of the surface.
M ^a _v M ^b _w M ^c _x Al _3-y Si _y N _z (I)
(In the formula, ^{Ma is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M b is} at least one element selected from the group consisting of Li, Na and K. It is an element, Mc 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 the formula (I), Ma preferably contains at least one of Ca and ^Sr from the viewpoint of obtaining high emission intensity. When Ma contains at least one of Ca and ^Sr , the total molar ratio of Ca and ^Sr contained in Ma is, for example, 85 mol% or more, preferably 90 mol% or more.
Further, M ^b preferably contains at least Li from the viewpoint of stability of the crystal structure. When M ^b contains Li, the molar ratio of Li contained in M ^b is, for example, 80 mol% or more, preferably 90 mol% or more.

V, w, x, y and z in the formula (I) are not particularly limited as long as they satisfy the above numerical range. From the viewpoint of the stability of the crystal structure, 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 the activation amount of at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and may be appropriately selected so as to achieve desired properties. It is more preferable that x satisfies 0.001 <x ≦ 0.020, and further preferably 0.002 ≦ x ≦ 0.015.

The fired product is at least one element (Ma element) selected from the group consisting of Ca, Sr, Ba and Mg and at least one element (M ^{b )} selected from the group consisting of Li, Na and K. Elements), at least one element ( ^Mc element) selected from the group consisting of Eu, Ce, Tb and Mn, Al and N, and Si as necessary. It can be obtained by mixing the raw materials and firing the obtained raw material mixture in an atmosphere containing nitrogen gas having a temperature of 1000 ° C. or higher and 1300 ° C. or lower and a pressure of 0.2 MPa or higher and 200 MPa or lower.
By firing the raw material mixture at a predetermined temperature in a pressurized atmosphere containing nitrogen gas, it is possible to efficiently produce a fired product used for a nitride phosphor having a desired composition and excellent emission intensity.

The raw material mixture used in the fired product is 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, and Al and N, and if necessary, a calcined product having a composition containing Si can be obtained as a raw material mixture thereof. The materials contained are not particularly limited. For example, the raw material mixture comprises 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 at least one element selected from the group consisting of Tb and Mn, a simple substance of a metal element constituting a composition containing Al and N, and optionally Si, and a metal compound thereof. Can include at least one of the following. Examples of such a metal compound include hydrides, nitrides, fluorides, oxides, carbonates, chlorides and the like, and are composed of hydrides, nitrides and fluorides from the viewpoint of improving light emission characteristics. It is preferably at least one selected from the group. When the raw material mixture contains oxides, carbonates, chlorides and the like as the metal compound, the content thereof is preferably 5% by mass or less, and more preferably 1% by mass or less in the raw material mixture. If these contents exceed a predetermined value, defects tend to occur in the crystal, which may reduce the emission intensity or increase the half width of the emission spectrum.

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 a metal compound containing Al. It preferably contains at least one metal compound selected from the group consisting of metal compounds containing Eu. Further, the raw material mixture may contain a metal compound containing Si, if necessary.

Specifically, as a metal compound containing a metal element (Ma element in the formula (I)) selected from the group consisting of Ca, Sr, Ba and Mg (hereinafter, also referred to as “first metal compound”), ^SrN ₂ , _{SrN , Sr3N2} , _SrH2 , _SrF2 , _Ca3N2 , _CaH2 , _CaF2 and the like can be mentioned, 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 and the like.

As the first metal compound, it is preferable to use a simple substance, but a compound such as an imide compound or an amide compound can also be used. The first metal compound may be used alone or in combination of two or more.

The metal compound containing a metal element (M ^b element in the formula (I)) selected from the group consisting of Li, Na and K (hereinafter, also referred to as “second metal compound”) preferably contains at least Li. , Li nitrides and hydrides are more preferred. When the second metal compound contains Li, a part of Li may be substituted with Na, K or the like, or may contain other metal elements constituting the nitride phosphor.
Specific examples of the _{second metal compound containing Li include Li 3N, 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 Ga and a group 13 element Ga and It may be a metal compound substituted with a metal element selected from the group consisting of In and the transition elements V, Cr and Co of the fourth period, 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 , LiAlH ₄ , and the like, 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 contained 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 _{3N 4, SiC, SiCl 4 , and} at least one selected from the group consisting of these. The metal compound containing Si may be used alone or in combination of two or more.

A metal compound containing a metal element ( ^Mc element in the formula (I)) selected from the group consisting of Eu, Ce, Tb and Mn (hereinafter, also referred to as “fourth metal compound”) is Eu as an activator. , Ce, Tb and Mn.
When the fourth metal compound is Eu, a part of Eu is replaced with Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like. May be good. By substituting a part of Eu with another element, the other element is considered to act as a co-activator, for example. By co-activating the nitride phosphor, the emission characteristics can be adjusted. When the mixture requiring Eu is used as the nitride phosphor, the compounding ratio can be changed if desired. Europium mainly has divalent and trivalent energy levels, but the calcined 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 calcined product used in the production method of the present embodiment contains divalent Eu as the center of light emission, but the divalent Eu is easily oxidized, and a metal compound containing trivalent Eu is used to form a raw material mixture. Can be done.

The raw material mixture may contain other metal elements, if necessary, in addition to the simple substance of the metal element and the metal compound. Other metal elements can usually form a raw material mixture as oxides, hydroxides, etc., but are not limited thereto, and are not limited to these, such as elemental metals, nitrides, imides, amides, and other inorganic salts. It may be in a state of being contained in the above-mentioned raw material mixture in advance.

The raw material mixture may contain a flux. When the raw material mixture contains flux, the reaction between the raw materials is promoted more, and further, the solid phase reaction proceeds more uniformly, so that the particle size is large and it is used to obtain a nitride phosphor having better emission characteristics. A fired product can be produced. It is considered that this is because, for example, the heat treatment for obtaining the fired product is performed at 1000 ° C. or higher and 1300 ° C. or lower, and this temperature is substantially the same as the formation temperature of the liquid phase such as a halide which is a flux. As the halide, rare earth metal, alkaline earth metal, alkali metal chloride, fluoride and the like can be used. As the flux, it can also be added as a compound having a target composition of a calcined product capable of obtaining an elemental ratio of cations. Further, the flux can be added in the form of further adding the flux to the raw material mixture in which each raw material is mixed so as to have the target composition of the obtained fired product.

When the raw material mixture contains 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 leads to a decrease in the emission intensity of the phosphor using the obtained calcined product. Is preferably, for example, 10% by mass or less, more preferably 5% by mass or less in the raw material mixture.

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

As the metal compound constituting the raw material mixture, SrNu (equivalent to _u = _2/3 , a mixture of Sr2N and SrN), _LiAlH4 , AlN, and _EuF3 powders are used, and they are used as Sr: Li: Eu: Al. After weighing in a glove box in an inert atmosphere so that the ratio of is 0.9925: 1.2000: 0.0075: 3.000, the mixture is mixed to obtain a raw material mixture. Here, Li is easily scattered during firing, so it is blended in a larger amount than the target composition. The present embodiment is not limited to this composition ratio. When a metal compound containing fluorine is used as a raw material, it is preferable that the content of fluorine in the fired product is finally 5% by mass or less. This is because if the fluorine content is larger than 5% by mass, pulverization is required after firing, and the pulverization deteriorates the particle shape of the fired product.

The raw material mixture is calcined in a nitrogen atmosphere. For firing, for example, a gas-pressurized electric furnace can be used. The firing temperature can be in the range of 1000 ° C. or higher and 1400 ° C. or lower, but is preferably 1000 ° C. or higher and 1300 ° C. or lower, and more preferably 1100 ° C. or higher and 1300 ° C. or lower. This is because when the firing temperature is low, it is difficult to form the target fluorescent compound, and when the firing temperature is high, the fluorescent compound is decomposed and the light emission characteristics are impaired.

Further, in the firing, a two-step firing (multi-step firing) is performed in which the first-stage firing is performed at 800 ° C. or higher and 1000 ° C. or lower, and the temperature is gradually raised to perform the second-step firing at 1000 ° C. or higher and 1400 ° C. or lower. You can also do it. 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 such as W or 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, more preferably 80% by volume or more.

Firing is performed in a pressurized atmosphere of 0.2 MPa or more and 200 MPa or less. The target nitride phosphor is more likely to decompose as the temperature rises, but by creating a pressurized atmosphere, decomposition can be suppressed and better light emission characteristics can be achieved. The gauge pressure of the pressurized atmosphere is preferably 0.2 MPa or more and 1.0 MPa or less, and more preferably 0.8 MPa or more and 1.0 MPa or less. By increasing the pressure of the atmospheric gas during firing, decomposition of the phosphor compound during firing is suppressed, and a fluorescent substance 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, 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, which are partially scattered during firing, are excluded from the composition formula. As described above, the actual composition contains oxygen derived from raw materials and a certain amount of oxygen due to oxidation generated in the process. In addition, by using fluoride, which is also effective as a flux component, as a raw material, a certain amount of fluorine is contained. Since decomposition, scattering, and the like occur during firing, Sr, Eu, and Li may be less than the theoretical composition when the charging composition ratio of Al is 3. Further, the composition of the target fired product can be changed by changing the blending ratio of each raw material.

Further, the method for producing the fired product is not limited to the above-mentioned production method. For example, elemental metals of each element are weighed to a predetermined composition ratio and then melted to form an alloy, and then the alloy is crushed, and a gas pressure sintering furnace, hot isostatic pressing, etc. are performed in a nitrogen gas atmosphere. A fired product having a target composition may be produced by a HIP furnace or the like using a hot isostatic pressing method (HIP).

The fired product preferably has a structure with high crystallinity at least in part. For example, since the vitreous body (amorphous body) has an irregular structure and low crystallinity, uneven chromaticity tends to occur if the reaction conditions in the production process cannot be controlled to be strictly uniform. The fired product used in the method according to the present embodiment is preferably a powder or a granular material having a structure with high crystallinity at least in part. A fired product having a structure with high crystallinity at least in part tends to be easy to manufacture and process. Further, since it is easy to uniformly disperse the nitride phosphor produced by using a fired product having a highly crystalline structure at least partially in the resin, a luminescent plastic, a polymer thin film material, etc. 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 crystalline phase having luminescence of the nitride phosphor produced by using the calcined product, and if the calcined product has a crystal phase of 50% by mass or more, the luminescence that can withstand practical use is emitted. It is preferable because the obtained nitride phosphor can be produced. Therefore, it is possible to produce a nitride fluorescent substance having an excellent emission intensity as the number of crystal phases of the fired product increases. As a result, the emission brightness of the nitride phosphor can be further increased, and processing can be facilitated.

[Step of heat-treating the fired product]
The method for producing a nitride phosphor according to an embodiment of the present invention includes contacting the fired product with a fluorine-containing substance and heat-treating at 200 ° C. or higher and 500 ° C. or lower. The fired product mainly constitutes a phosphor core of a nitride phosphor.

The nitride phosphor produced by the method according to the present embodiment contains fluorine on or near the surface of the fired product by contacting the fired product with a fluorine-containing substance and heat-treating at 200 ° C. or higher and 500 ° C. or lower. It is presumed that a compound is formed and this fluorine-containing compound serves as a protective film. By using such a nitride phosphor, it is possible to manufacture a light emitting device having excellent durability with little change in chromaticity even in an environment where the temperature and humidity are relatively high.

The fluorine-containing substance is not particularly limited as long as it is a substance containing 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 , NF ₃ and the like.
The fluorine-containing substance 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 . Is preferable.
The fluorine-containing substance is more preferably 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 state or a 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 in contact with the fluorine-containing substance in a solid state at room temperature is 20 ° C or higher and lower than 200 ° C, the fired product is brought into contact with the fluorine-containing substance and then heat-treated at 200 ° C or higher and 500 ° C or lower. To do.

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

When the fluorine-containing substance is a gas, the fired product may be placed in an atmosphere containing the fluorine-containing substance and brought into contact with the fired product. When the fluorine-containing substance is a gas, the fired product is placed in an atmosphere containing the fluorine-containing substance, and the fired product is heat-treated at 200 ° C. or higher and 500 ° C. or lower in the atmosphere containing the fluorine-containing substance. When the fluorine-containing substance is F ₂ (fluorine gas) and the fired product is heat-treated at 200 ° C. or higher and 500 ° C. or lower in an atmosphere containing F ₂ , the F ₂ concentration in the atmosphere is preferably 2% by volume or more. It is 25% by volume or less, more preferably 5% by volume or more and 20% by volume or less. If the F ₂ concentration in the atmosphere is less 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 significantly lowered due to the fluorination of the mother body of the phosphor.

The heat treatment is preferably carried out in an atmosphere of an inert gas. The inert gas atmosphere means an atmosphere containing argon, helium, nitrogen or the like as the main components of the atmosphere. The inert gas atmosphere may contain oxygen as an unavoidable impurity, but here, if the concentration of oxygen contained in the atmosphere is 15% by volume or less, the atmosphere is an inert gas atmosphere. The concentration of oxygen in the atmosphere of the inert gas is preferably 10% by volume or less, more preferably 5% by volume or less, still more preferably 1% by volume or less. This is because if the oxygen concentration is equal to or higher than a predetermined value, the particles of the phosphor may be overoxidized. When the fluorine-containing substance is a gas, it is preferable to perform the heat treatment in an atmosphere containing the inert gas and the fluorine-containing substance, in consideration of safety, rather than performing the heat treatment in the atmosphere of the fluorine-containing substance alone.

The temperature at which the fired product and the fluorine-containing substance are brought into contact with each other for heat treatment is 200 ° C. or higher and 500 ° C. or lower. The temperature for heat treatment is more preferably 250 ° C. or higher and 450 ° C. or lower, further preferably 250 ° C. or higher and 400 ° C. or lower, and even more preferably 250 ° C. or higher and 350 ° C. or lower.
If the temperature to be heat-treated is lower than a predetermined temperature, it is difficult to form a compound containing fluorine on or near the surface of the fired product, and a durable nitride phosphor cannot be produced. On the other hand, if the temperature to be heat-treated exceeds a predetermined temperature, it is considered that the crystal structure of the fired product is likely to be destroyed, so that it is not possible to produce a nitride phosphor having high durability.

The time for performing the heat treatment is not particularly limited, but is preferably 1 hour or more and 10 hours or less, and more preferably 2 hours or more and 8 hours or less. If the heat treatment time is 1 hour or more and 10 hours or less, the fired product and the fluorine-containing substance are brought into contact with each other for heat treatment to form a layer of a fluorine-containing compound on or near the surface of the fired product. It is presumed that this layer functions as a protective film, so that the durability of the light emitting device can be improved.

[Post-treatment process]
The method for producing a nitride fluorophore according to the present embodiment may include a post-treatment step of performing a crushing treatment, a pulverizing treatment, a classification treatment, 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 has at least one element selected from the group consisting of Ca, Sr, Ba and Mg and at least one selected from the group consisting of Li, Na and K. On the surface of a 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 Si. It has a layer of compounds containing fluorine. In the nitride phosphor of the present embodiment, Si may be contained in a part of Al, O may be contained by oxidation of the surface, and a part of N may be replaced with O, which is 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 fired product having a composition represented by the general formula (I) and a fluorine-containing substance are brought into contact with each other and have a temperature of 200 ° C. or higher and 500 ° C. or lower. By heat-treating with, a layer of a compound containing fluorine is formed on the surface or a portion close to the surface of the fired product. The layer of the compound containing fluorine serves as a protective film, and the inside of the nitride phosphor is less likely to be affected by the external environment. The nitride phosphor of the present 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 layer of the compound containing fluorine existing on the surface. It becomes difficult to react with the elements that form and has excellent durability. Therefore, the light emitting device using the nitride phosphor according to the embodiment of the present invention has excellent 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 surface of a phosphor core having a composition represented by the following general formula (I) and a layer of a compound containing fluorine not represented by the following general formula (I). Have in. In the composition represented by the following general formula (I), a part of N may be replaced with O, a part of N may be replaced with F, and a part of N may be replaced with 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, ^{Ma is at least one element selected from the group consisting of Ca, Sr, Ba and Mg, and M b is} at least one element selected from the group consisting of Li, Na and K. It is an element, Mc 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 the formula (I), Ma preferably contains at least one of Ca and ^Sr from the viewpoint of obtaining high emission intensity. When Ma contains at least one of Ca and ^Sr , the total molar ratio of Ca and ^Sr contained in Ma is, for example, 85 mol% or more, preferably 90 mol%.
Further, M ^b preferably contains at least Li from the viewpoint of crystal structure stability. When M ^b contains Li, the molar ratio of Li contained in 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 above numerical range. 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 the activation amount of at least one element selected from the group consisting of Eu, Ce, Tb and Mn, and may be appropriately selected so as to achieve desired properties. x preferably satisfies 0.001 <x ≦ 0.020, and more preferably 0.002 ≦ x ≦ 0.015.

The nitride phosphor of the present embodiment has a fluorine (F) content of preferably 1.0% by mass or more and 10.0% by mass or less, more preferably 2.0% by mass or more 8 in the nitride phosphor. It is 0.0% by mass or less, more preferably 2.5% by mass or more and less than 7.5% by mass.
In the nitride phosphor of the present embodiment, a layer of a compound containing fluorine is present on or near the surface of the phosphor core. In the nitride phosphor of the present embodiment, not only fluorine is present in the layer of the compound containing fluorine existing on or near the surface of the nitride phosphor, but also fluorine is present in the crystal structure of the nitride phosphor core. May exist. Fluorine present in the crystal structure of the nitride phosphor core is derived from, for example, oxygen mixed by the oxidation of the nitride phosphor and Ca, Sr, Ba and Mg contained in the crystal structure of the nitride phosphor. ^A compound containing at least one element (Ma element) and Al element selected from the above group, and ^a compound containing Ma element, Al, oxygen (O), and fluorine (F) may be formed.

The nitride phosphor of the present embodiment has a layer of a compound containing fluorine on the surface or a portion close to the surface of the phosphor core, and the layer of the compound containing fluorine includes the first layer and the first layer. It is preferable to have a second layer having a composition different from that of the above 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 to have a temperature of 200 ° C. or higher and 500 ° C. or lower. By heat-treating 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 the compound containing fluorine, are formed by embedding the nitride phosphor in an epoxy resin as described in Examples described later. After the epoxy resin is cured, it is cut so that the cross section of the nitride phosphor is exposed, and the cross section can be confirmed by observing the cross section using a scanning electron microscope (SEM). 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 phosphor core is located on or near the surface of the phosphor core constituting the nitride phosphor. Separately, two layers with different shades of contrast can be identified.

In the nitride phosphor of the present embodiment, the first layer of the layer of the compound containing fluorine contains at least one element selected from the group consisting of Ca, Sr, Ba and Mg and fluorine, and the second layer. The layer is preferably containing 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 contacting the fired product with the fluorine-containing substance and heat-treating at a temperature of 200 ° C. or higher and 500 ° C. or lower. It is believed that at least one selected element reacts with fluorine to form a stable fluoride-containing first layer on the surface of the nitride phosphor. 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 presence and amount of lattice defects and the like, are used to form the nitride phosphor. Fluorine in the fluorine-containing substance brought into contact with the object 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 contains at least one element selected from the group consisting of Ca, Sr, Ba and Mg, Al and fluorine (F), and elements constituting the crystal structure of the nitride phosphor. Nitrogen (N) may be contained.

The nitride fluorophore of the present embodiment preferably has the first layer on the surface and the second layer inside 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 to have a temperature of 200 ° C. or higher and 500 ° C. or lower. By heat treatment at 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 which forms the skeleton of the crystal structure of the nitride phosphor on the surface side which is the interface in contact with air. It is preferable to have a first layer containing a fluoride having a stable structure containing the elements of the above and fluorine. The nitride phosphor of the present embodiment has excellent durability even in an environment where the temperature and humidity are relatively high because the first layer containing fluoride having a stable structure is formed on the surface.
Further, the nitride phosphor of the present embodiment has a second layer having a composition different from that of the first layer inside the first layer formed on the surface side, and this second layer is nitrided. It is preferably formed from a compound containing at least one element selected from the group consisting of Ca, Sr, Ba and Mg forming the skeleton of the crystal structure of the fluorescent substance and Al and fluorine. The nitride phosphor of the present embodiment has a second layer inside the first layer, and the second layer has a composition including Al constituting the crystal structure of the nitride phosphor. By containing 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 becomes the first layer on the surface of the nitride phosphor. Is thought to be more tightly coupled.
The nitride phosphor of the present embodiment has a stable first layer on the surface side, and by having a second layer inside the first layer, the inside of the nitride phosphor is external. It is less susceptible to the influence of the environment and has excellent durability even in an environment where the temperature and humidity are relatively high.

For example, when the nitride phosphor of the present embodiment is produced using a calcined product having the composition of Sr _0.993 Eu _{0.007 LiAl} 3N ₄ as the design composition, the layer of the compound containing fluorine is formed. 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 calcined product having a composition of Sr _0.993 Eu _{0.007 LiAl} 3N ₄ is used as the design composition, the nitride phosphor of the present embodiment has Sr element and fluorine (Sr element and fluorine) as the first layer. It is preferably formed of a compound containing F), and the second layer is formed of a compound containing an Sr element, fluorine (F), and an Al element constituting the crystal structure of the nitride phosphor. Is preferable. The second layer may contain a compound containing Sr element, Al element, F element and N element constituting the crystal structure of the nitride phosphor.

The thickness of the fluorine-containing compound layer of the phosphor according to the present 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.
When the layer of the compound containing fluorine of the nitride phosphor has a first layer and a second layer, the total thickness of the first layer and the second layer is 0.05 μm or more. It is preferably 8 μm or less.
When the thickness of the layer of the compound containing fluorine of the nitride phosphor is less than 0.05 μm, the thickness is small, so that the function as a protective film is small even when the layer of the compound containing fluorine is present. It is easily affected by the external environment such as temperature and humidity, and its durability may be lower than that of a nitride phosphor having a layer thickness of a compound containing fluorine of 0.05 μm or more.
When the thickness of the layer of the compound containing fluorine of the nitride phosphor according to the present embodiment exceeds 0.8 μm, the thickness of the layer of the compound containing fluorine becomes large, light reflection and the like become large, and the nitride When a phosphor is used in a light emitting device, the desired light emitting intensity may not be obtained.
In the nitride phosphor according to the present embodiment, the thickness of the layer of the compound containing fluorine is determined by embedding the nitride phosphor in the epoxy resin and curing the epoxy resin as described in Examples described later. The cross section of the phosphor is cut so as to be exposed, the cross section is observed using a scanning electron microscope (SEM), and the dimension of the thickness of the layer of the compound 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 backscattered electron image of the cross section of the nitride phosphor, the layer of the compound containing fluorine has an average thickness of about 0.1 μm.
In the nitride phosphor according to the present embodiment, the average thickness of the layer of the compound containing fluorine is 0.05 μm or more and 0.3 μm or less.

The nitride phosphor of the present embodiment absorbs light in a wavelength range of 400 nm or more and 570 nm or less, which is a region on the short wavelength side of visible light from ultraviolet rays, and emits fluorescence having a emission peak wavelength in a wavelength range of 630 nm or more and 670 nm or less. It is preferably emitted.

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

In the nitride phosphor of the present embodiment, the rare earths europium (Eu), Ce, Tb, or Group 7 Mn is the center of light emission. 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 contained, other rare earth metals or alkaline earth metals are part of Eu. It can also be used by replacing it with Eu and co-activating it with Eu. For example, Eu ²⁺ , which is a divalent rare earth ion, exists stably and emits light by selecting an appropriate mother body.

From the viewpoint of emission intensity, the average particle size 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. The average particle size is, for example, 20 μm or less, preferably 18 μm or less. 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 the excitation light to the nitride phosphor tend to be higher. As described above, by including the nitride phosphor having excellent light emitting characteristics in the light emitting device described later, the light emitting efficiency of the light emitting device is increased. Further, 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.

In the present specification, the average particle size of the nitride phosphor and the average particle size of other phosphors are the volume average particle size, the laser diffraction type particle size distribution measuring device (product name: MASTER SIZER 2000, MALVERN). It is a particle size (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.
The light emitting device according to the embodiment of the present invention includes the nitride phosphor according to the embodiment of the present invention and an excitation light source.

The excitation light source used in the light emitting device according to the present 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, it is possible to provide a phosphor having high emission intensity. In particular, it is more preferable to use an excitation light source having a main emission peak wavelength at 420 nm or more and 500 nm or less, and it is further preferable to use an excitation light source having a main emission peak wavelength at 420 nm or more and 460 nm or less. By using the light emitting element having the emission peak wavelength as an excitation light source, it is possible to configure a light emitting device that emits a mixed color light of the light from the light emitting element and the fluorescence from the phosphor.

The half width of the emission spectrum of the light emitting element can be, for example, 30 nm or less.
It is preferable to use a semiconductor light emitting device as the light emitting device. By using a semiconductor light emitting device as a light source, it is possible to obtain a stable light emitting device having high efficiency, high output linearity with respect to input, and resistance to mechanical impact.
As the semiconductor light emitting device, for example, a semiconductor light emitting device using a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 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 or more and 570 nm or less, has an emission peak wavelength in a wavelength range of 630 nm or more and 670 nm or less, and has a reflectance at 650 nm. The reflectance ratio at 460 nm is preferably 2 or more. The details of the nitride fluorophore are as described above, and the preferred form is also the same. The light emitting device preferably includes a first phosphor containing the nitride phosphor and a second phosphor.

The first phosphor can be contained in, for example, a sealing member covering an excitation light source to form a light emitting device. In a light emitting device in which the excitation light source is covered with a 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, the 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 depending on the color or the like finally desired. 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 a 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 properties by appropriately providing a light emitting element that emits blue light and a first phosphor and a second phosphor excited by the light emitting element. ..

As the second fluorescent substance, for example, a fluorescent substance having a composition represented by any of the following formulas (IIa) to (IIi) can be mentioned, and a composition represented by a formula selected from the group consisting of these can be mentioned. It is preferable to contain at least one kind of fluorescent substance having. For example, it is more preferable to contain at least one fluorescent substance having the composition represented by the formula (IIc), (IIe) or (IIi) in that a wide color reproduction range can be obtained. Further, it is more preferable to contain at least one fluorescent substance having the composition represented by the formula (IIa), (IId), (IIf) or (IIg) in terms of obtaining high color rendering properties.
(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 Op} 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 size 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, 1% by mass or more and 200% by mass or less with respect to the resin, and is preferably 2% by mass or more and 180% by mass or less.

The content ratio of the first fluorescent substance to the second fluorescent substance (first fluorescent substance / second fluorescent substance) can be, for example, 0.01 or more and 5.00 or less as a mass ratio, and 0. It is preferably 05 or more and 3.00 or less.

The first fluorescent substance and the second fluorescent substance (hereinafter, also simply referred to as “fluorescent material”) 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 resin, epoxy resin, epoxy-modified silicone resin, and modified silicone resin.

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

The sealing member may further contain 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 the sealing member contains a filler, the content thereof can be appropriately selected depending on the purpose and the like. The content of the filler can be, for example, 1% by mass or more and 20% by mass or less with respect to 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 the present embodiment. This light emitting device is an example of a surface mount type light emitting device.

The light emitting device 100 includes a package having recesses formed by the lead electrodes 20 and 30 and the molded body 40, a light emitting element 10, and a fluorescent member 50 that covers the light emitting element 10. The light emitting element 10 is arranged in the recess of the package, and is electrically connected to the pair of positive and negative lead electrodes 20 and 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 for wavelength-converting the light from the light emitting element 10 and a resin. Further, the fluorophore 70 includes a first fluorophore 71 and a second fluorophore 72. A part of the positive and negative lead electrodes 20 and 30 is exposed on the outer surface of the package. The light emitting device 100 emits light by receiving electric power from the outside through these lead electrodes 20 and 30.

The fluorescent member 50 contains 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 with reference to Examples.

(Making a fired product)
A fluorescent material having a composition containing Sr, Li, Eu, Al, and N was produced.
Specifically, as a phosphor having a composition represented by the general formula (I) M ^a _v M ^b _w M ^c _x Al _3-y S _y N _z , ^{Ma is Sr, M b is} Li, M. ^c was Eu, and SrNu (equivalent to _u = _2/3 , a mixture of Sr2N and SrN), _SrF2 , _LiAlH4 , AlN, and EuF ₃ were used as raw materials. In this example, y in the general formula (I) is 0. In the glove box with an inert gas atmosphere, the molar ratio of the above-mentioned raw materials as the charging amount ratio is Sr: Li: Eu: Al = 0.9925: 1.2000: 0.0075: 3.000. After weighing, the mixture was mixed to obtain a raw material mixture. Here, the mass ratio of _SrNu and _SrF2 was set to 94: 6. In addition, Li (lithium) is easily scattered during firing, so a larger amount than the theoretical value was added. The raw material mixture was filled in the _rutsubo , and the gas pressure was 0.92 MPa (absolute pressure 1.02 MPa) as the gauge pressure in a nitrogen gas atmosphere, the temperature was 1100 ° C., and the heat treatment was performed for ₃ hours. A fired product having a composition represented by _.0075 Al ₃ N ₄ was obtained. Then, this fired product was dispersed and classified to obtain a fired product 1.

(Example 1)
The fired product 1 contains fluorine gas (F ₂ ) and nitrogen gas (N ₂ ), and the temperature is 300 ° C. and the treatment time is set in an atmosphere where the fluorine gas concentration is 20% by volume and the nitrogen gas concentration is 80% by volume or more. The heat treatment was carried out for 8 hours to obtain a powder of the nitride phosphor of Example 1.

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

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

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

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

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

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

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

(Example 6)
The fluorophore 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 fluorophore 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 calcined product 1 and ammonium fluoride, and nitrogen gas (N ₂ ) is 90% by volume or more. Heat treatment was performed in the containing atmosphere at a temperature of 200 ° C. and a treatment time of 2 hours to obtain a nitride phosphor powder.

(Example 9)
A nitride fluorophore powder was obtained under the same conditions as in Example 8 except that the temperature was set to 300 ° C.

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

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

<Evaluation>
(X-ray diffraction spectrum)
The X-ray diffraction spectrum (XRD) of the obtained nitride phosphor was measured. The measurement was performed using a sample horizontal multipurpose X-ray diffractometer (product name: UltimaIV, Rigaku Co., Ltd.) and CuKα rays. 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, Examples 1 and 5, in order from the top, and as a reference example, the XRD patterns of the compounds represented by SrF ₂ and LiSrAlF ₆ are shown. show.

(Light emission 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.) with the wavelength of the excitation light set to 450 nm. The energy (relative emission intensity:%) of the obtained emission spectrum was determined. The results are shown in Table 1. The relative emission intensity was calculated with the nitride phosphor of Comparative Example 1 as 100%. The emission peak wavelength was 650 to 660 nm in both Comparative Examples 1 to 4 and Examples 1 to 10. Further, FIG. 3 shows the emission spectra of the 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 an ICP emission spectrometry method using an inductively coupled plasma emission spectrometer (manufactured by Perkin Elmer). When the content of fluorine (F) is less than 1.0% by mass, quantitative analysis is performed using an ion chromatograph (ICS-1500 manufactured by DIONEX) by an ion chromatography method, and the content of fluorine (F) is high. In the case of 1.0% by mass or more, quantitative analysis was performed by a UV-VIS method using a double beam spectrophotometer (U-2900 manufactured by HITACHI). The content of the fluorine element in the nitride phosphor was determined, and the results are shown in Table 1.

(Storage test)
Light emitting devices were manufactured using the obtained nitride phosphors. A sealing material dispersed in a silicone resin, with the nitride phosphors of the Examples and Comparative Examples as the first phosphor and β-sialon, which is a green phosphor, as the second phosphor, and a nitride having a main wavelength of 451 nm. A surface-mounted light emitting device having a chromaticity (x, y) = (0.25, 0.22) was manufactured by sealing the system semiconductor light emitting element. After storing this light emitting device at a temperature of 85 ° C. and a relative humidity of 85% for 100 hours, the chromaticity x was measured and determined as the amount of change (absolute value) with respect to the chromaticity x before the storage test.

(SEM image-secondary electron image)
Using a scanning electron microscope (SEM), 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. FIG. 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 photograph of the nitride phosphor of Example 5. It is a photograph, and FIG. 8 is an SEM photograph of the nitride phosphor of Comparative Example 3.

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

(Average particle size)
For the obtained nitride phosphor, the volume average particle size (median diameter) measured by a laser diffraction type particle size distribution measuring device (product name: MASTER SIDER 2000, manufactured by MALVERN) is the average particle size. And said.

Table 1 shows the contact conditions and heat treatment conditions between the fired product of Examples and Comparative Examples and the fluorine-containing substance. In Table 1, Comparative Examples 2 and 3, Examples 1 to 5, Comparative Example 4, and Examples 8 and 9 have the same 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 the additional heat treatment different from the contact condition were performed, and the conditions are described in Table 1.

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

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 _0.0075 Al ₃ N ₄ of Comparative Example 1 in composition. It was confirmed that it was a compound. In Examples 1 and 5, the same peaks as those shown by the compounds represented by SrF ₂ and LiSrAlF ₆ appear in the vicinity of 2θ of 25 ° to 27 °, and from this result, fluorine element is contained. It can be confirmed that there is. In the light emitting device of the embodiment, it is considered that the layer of the compound containing fluorine formed on or near the surface of the fired product constituting the phosphor core of the nitride phosphor functions as a protective film, and under the above environment. The change in chromaticity x is small, and the durability is excellent.

As shown in FIG. 3, the emission spectrum of the relative emission intensity with respect to the wavelength of the nitride phosphors of Examples 1, 3 to 5 and 7 has almost the same emission spectrum as the emission spectrum of the nitride phosphor of Comparative Example 1. Since the peak shape of the emission spectrum of the example was maintained and the peak shape of the emission spectrum of the example was almost the same as that of Comparative Example 1, it is presumed that the crystal structure did not change even by the heat treatment and the crystal structure was 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 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 cross section 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 and the vicinity of the surface of the phosphor core 3 constituting the nitride phosphor 3 in addition to the phosphor core 3. You can see two layers. 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, which form the crystal structure of the nitride phosphor, and is the first layer. The second layer 2 existing inside the first 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.
In the nitride phosphor shown in FIG. 7, the first layer 1 and the second layer 2 containing a compound containing fluorine function as a protective film, and the nitride phosphor is nitrided in the vicinity of the surface of the nitride phosphor. An alkaline earth metal element (for example, an element selected from the group consisting of Ca, Sr, Ba and Mg) or an alkali metal element (for example, an element selected from the group consisting of Li, Na and K) constituting a material phosphor. ) Is less likely to react with carbon dioxide, moisture, etc., and it is considered that the durability is improved.

When the total thickness of the first layer 1 and the second layer 2 is obtained 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 layers of the compound containing fluorine is 0. It is about 1 μm, the thickness of the layer of the thinnest part is about 0.05 μm, and the thickness of the layer of the thickest part 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 a fluorine element due to the influence of the fluorine compound contained in the raw material, but the calcined product and the fluorine-containing substance are brought into contact with each other. 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 large as compared with the examples, and the durability was not improved.
The nitride phosphor of Comparative Example 2 is in contact with the fired product and the fluorine-containing substance, but since it has not been heat-treated, a layer of the compound 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 under the above environment is larger than that in the examples.
The nitride phosphors of Comparative Examples 3 and 4 are heat-treated by contacting the fired product with a fluorine-containing substance, but the heat treatment temperature is 150 ° C., which is lower than that of the examples, so that the compound containing fluorine is protected. It is considered that the membrane is not sufficiently formed. In the nitride phosphor of Comparative Example 3, it was confirmed by the backscattered electron image of the cross section that the layer of the compound containing fluorine was not formed as 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 material phosphor and the SEM photograph of the nitride phosphor of Example 5 shown in FIG.
However, as shown in the backscattered 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 on 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, the first element containing the elements constituting the nitride phosphor, for example, Sr and fluorine (F), which are different from the phosphor core 3, are contained in the particles of the nitride phosphor. Compound 5 is formed.
Further, as shown in FIG. 9, the nitride phosphor may contain a compound 4 of aluminum nitride in addition to the phosphor core 3.
In FIG. 9, reference numeral 6 is a second compound having a structure different from that of the phosphor core 3, and as a result of composition analysis, contains Sr and fluorine (F), and further contains Al and oxygen (O).

From the results shown in Table 1, the nitride phosphor according to the present embodiment maintains high emission intensity, and the change in chromaticity is suppressed even after storage in the above environment. As described above, since the nitride phosphor produced by the method according to the present embodiment has excellent durability, it is possible to provide a highly reliable light emitting device by using this nitride phosphor.

A highly durable nitride phosphor can be obtained by the production 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 lighting or the like. In particular, it can be suitably used for lighting light sources, LED displays, liquid crystal backlight light sources, traffic lights, lighting switches, various sensors, various indicators, etc., which use a light emitting diode as an excitation light source and have extremely excellent light emission characteristics.

1: First layer, 2: Second layer, 3: Fluorescent core, 4: AlN-based compound, 5: First compound, 6: Second compound, 10: Light emitting element, 40: Molded body, 50: Sealing member, 71: First phosphor, 72: Second phosphor, 100: Light emitting device.

Claims (11)

A method for producing a nitride phosphor containing a phosphor core having a composition containing Sr, Li, Eu, Al, and N.
Preparing a fired product having the above composition and
A method for producing a nitride phosphor, which comprises contacting the fired product with a fluorine-containing substance in an atmosphere of an inert gas and heat-treating the fired product at a temperature of 200 ° C. or higher and 350 ° C. or lower. The fluorine-containing substance 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 fired product is brought into contact with the fluorine-containing substance at a temperature lower than the temperature of the heat treatment, and then the heat treatment is performed in an air atmosphere. The method for producing a nitride phosphor according to claim 3, wherein the temperature at which the fired product is brought into contact with the fluorine-containing substance is 20 ° C. or higher and lower than 200 ° C. The fluorine-containing substance is at least one selected from the group consisting of NH ₄ HF ₂ , HN ₄ F, KrF ₂ , XeF ₂ and XeF ₄ , and the total amount of the calcined product and the fluorine-containing substance is 100% by mass. The method for producing a nitride phosphor according to claim 1, wherein a fluorine-containing substance in a solid state of 1% by mass or more and 10% by mass or less is brought into contact with the fired product. The method for producing a nitride phosphor according to any one of claims 1 to 4, wherein the fluorine-containing substance is fluorine gas. The method for producing a nitride fluorescent substance according to claim 1 or 2, wherein the heat treatment is performed in an atmosphere of an inert gas. The nitride according to claim 1, 3, 4, 6 or 7, wherein the fluorine-containing substance is fluorine gas, and the atmosphere contains 2% by volume or more and 20% by volume or less of fluorine gas and 80% by volume or more of nitrogen gas. Method for producing a phosphor. The method for producing a nitride phosphor according to any one of claims 1 to 8, wherein the time for performing the heat treatment is 1 hour or more and 10 hours or less. A layer of a compound containing fluorine is provided on the surface of a phosphor core having a composition containing Sr, Li, Eu, Al, and N.
The layer of the compound containing fluorine has at least a first layer and a second layer having a composition different from that of the first layer.
The first layer contains Sr and fluorine and contains
The second layer contains Sr, Al, fluorine and nitrogen.
A nitride fluorophore having the first layer on the surface and the second layer inside the first layer. The nitride phosphor according to claim 10, wherein the thickness of the layer of the compound containing fluorine is 0.05 μm or more and 0.8 μm or less.

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