JP7071683B2 - Nitride phosphor manufacturing method - Google Patents

Description

The present disclosure relates to a method for producing a nitride fluorophore.

Emission that can emit light of various hues by the principle of light color mixing by combining a light source and a wavelength conversion member that is excited by the light from this light source and can emit light with a hue different from that of the light source. The device is being developed. In particular, light emitting devices formed by combining light emitting diodes (hereinafter referred to as "LEDs") and phosphors have been actively applied to lighting devices, backlights of liquid crystal display devices, etc., and are widely used. Is progressing. For example, in a white light emitting device, a liquid crystal display device is formed by combining a phosphor that emits light at a short wavelength such as blue-green, green, or yellow-green and a phosphor that emits light at a long wavelength such as orange or red. It is possible to improve the color reproduction range and the color playability of the lighting device.

As a fluorescent substance having little decrease in brightness even with high-energy excitation, a fluorescent substance having an inorganic crystal whose crystal structure contains nitrogen, such as a sialone fluorescent substance, an oxynitride fluorescent substance, and a nitride fluorescent substance, has been proposed. .. Among these, as an example of the nitride fluorescent substance, a red fluorescent substance (hereinafter referred to as "CASN fluorescent substance") activated by Eu ²⁺ using CaAlSiN ₃ as a parent crystal and a part of Ca of the CASN fluorescent substance are used as Sr. Substituted (Sr, Ca) AlSiN ₃ : Eu (hereinafter referred to as “SCASSN fluorophore”) is known. The CASN fluorophore and SCASN fluorophore have emission peak wavelengths in a wide range of 610 to 680 nm. The half-value width of these emission spectra is relatively narrow at 75 to 95 nm, but when used as a light-emitting device for a liquid crystal display device, further improvement in the color reproduction range is desired, and a phosphor having a narrower half-value width is desired. It is rare.

In recent years, SrLiAl ₃ N ₄ : Eu (hereinafter referred to as "SLAN phosphor") has been proposed as a new nitride phosphor having a narrow half-value width of 70 nm or less. The emission peak wavelength of this compound is around 650 nm (see, for example, Patent Document 1 and Non-Patent Document 1). This SLAN phosphor is a raw material powder containing, for example, lithium aluminum hydride (LiAlH ₄ ), aluminum nitride (AlN) and europium fluoride (EuF ₃ ), measured in a chemical ratio such that Eu = 0.4 mol%. After mixing, the mixture is placed in a tungsten lure and fired in a high-frequency heating furnace at 1000 ° C. for 2 hours under an atmospheric pressure of a mixed gas atmosphere of hydrogen and nitrogen.

International Publication No. 2013/175336

Nature Materials, NMAT4012, 2014

However, in the SLAN phosphor obtained by the above manufacturing method, there is room for improvement in the internal quantum efficiency, and a fluorescent material having higher luminous efficiency is desired.
Therefore, an object of the embodiment according to the present disclosure is to provide a nitride phosphor having excellent luminous efficiency.

Specific means for solving the above problems are as follows, and the present disclosure includes the following aspects.
The first aspect has the composition represented by the following formula (I), is excited by light in the wavelength range of 400 nm or more and 570 nm or less, has an emission peak wavelength in the range of 630 nm or more and 670 nm or less, and has a reflectance at 650 nm. It is a nitride phosphor having a ratio of 2 or more to the reflectance at 460 nm.
M ^a _w M ^b _x Eu _y Al ₃ 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. Yes, w, x, y and z are 0.8 ≦ w <1.0, 0.5 ≦ x <1.0, 0.001 <y ≦ 0.1, z = (2/3) w +, respectively. Satisfy (1/3) x + (2/3) y + 3.

The second aspect is a method for producing a nitride phosphor having a composition represented by the following formula (I), wherein the raw material mixture has 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. A method for producing a nitride fluorophore, which comprises treating in an atmosphere containing nitrogen gas.
M ^a _w M ^b _x Eu _y Al ₃ 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. Yes, w, x, y and z are 0.8 ≦ w <1.0, 0.5 ≦ x <1.0, 0.001 <y ≦ 0.1, z = (2/3) w +, respectively. Satisfy (1/3) x + (2/3) y + 3.

According to one embodiment of the present disclosure, it is possible to provide a nitride fluorescent substance having excellent luminous efficiency.

It is a schematic sectional drawing which shows an example of the light emitting device which concerns on this embodiment. 5 is an X-ray diffraction pattern of the nitride phosphor according to Comparative Example 1 and Examples 1 and 2. 6 is an emission spectrum showing the relative emission intensity with respect to the wavelength of the nitride phosphors according to Comparative Examples 1 and 2 and Examples 1, 2 and 3. 6 is a reflection spectrum showing the reflectance with respect to the wavelength of the nitride phosphors according to Comparative Examples 1 and 2 and Examples 1, 2 and 3. This is an example of an SEM image of the nitride phosphor according to Comparative Example 1. This is an example of an SEM image of the nitride phosphor according to Comparative Example 2. It is an example of the SEM image of the nitride phosphor which concerns on Example 1. It is an example of the SEM image of the nitride phosphor which concerns on Example 2. It is an emission spectrum which shows the relative emission intensity with respect to the wavelength about the light emitting apparatus which concerns on Example A and Comparative Example A. It is an emission spectrum which shows the relative emission intensity with respect to the wavelength about the light emitting apparatus which concerns on Example B and Comparative Example B.

Hereinafter, the nitride fluorescent substance according to the present disclosure, a method for producing the same, and a light emitting device will be described based on the embodiments and examples. However, the embodiments shown below exemplify a nitride fluorescent substance or the like for embodying the technical idea of the present invention, and the present invention specifies the nitride fluorescent substance or the like to the following. do not. 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.

(Nitride phosphor)
The nitride phosphor according to the present embodiment has a composition represented by the following formula (I), is excited by light having a wavelength range of 400 nm or more and 570 nm or less, and has an emission peak wavelength in the range of 630 nm or more and 670 nm or less. The ratio of the reflectance at 650 nm to the reflectance at 460 nm is 2 or more.
M ^a _w M ^b _x Eu _y Al ₃ 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. Yes, w, x, y and z are 0.8 ≦ w <1.0, 0.5 ≦ x <1.0, 0.001 <y ≦ 0.1, z = (2/3) w +, respectively. Satisfy (1/3) x + (2/3) y + 3.

When the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) of the reflectance (R ⁶⁵⁰ ) at 650 nm to the reflectance (R ⁴⁶⁰ ) at 460 nm is 2 or more, excellent luminous efficiency can be achieved. The reflectance ratio is preferably 2.2 or more, more preferably 2.5 or more. The upper limit of the reflectance ratio is not particularly limited, and is, for example, 10 or less, preferably 9 or less.

The reflectance of the nitride phosphor at 460 nm is not particularly limited as long as the reflectance ratio is satisfied, and is, for example, 35% or less, preferably 30% or less. The lower limit of the reflectance at 460 nm is not particularly limited, and is, for example, 5% or more, preferably 10% or more. The reflectance at 650 nm is, for example, 60% or more, preferably 65% or more. The upper limit of the reflectance at 650 nm is not particularly limited, and is, for example, 100% or less, preferably 95% or less.

The nitride phosphor has an average reflectance ratio (R ^640-670 ) to an average reflectance (R ^450-470 ) in the wavelength range of 450 nm or more and 470 nm or less in the wavelength range of 640 nm or more and 660 nm or less ^{. 660} / R ^450-470 ) is preferably 2 or more, more preferably 2.2 or more, and even more preferably 2.5 or more. The upper limit of the average reflectance ratio is not particularly limited, and is, for example, 10 or less, preferably 9 or less. When the average reflectance ratio is in the above range, more excellent luminous efficiency tends to be achieved.

The average reflectance of the nitride phosphor in the wavelength range of 450 nm or more and 470 nm or less is, for example, 35% or less, preferably 30% or less. The lower limit of the average reflectance in the wavelength range of 450 nm or more and 470 nm or less is not particularly limited, and is, for example, 5% or more, preferably 10% or more. The average reflectance in the wavelength range of 640 nm or more and 660 nm or less is, for example, 60% or more, preferably 65% or more. The upper limit of the average reflectance in the wavelength range of 640 nm or more and 660 nm or less is not particularly limited, and is, for example, 100% or less, preferably 95% or less.

Here, the average reflectance is calculated as an arithmetic mean value of the measured reflectance by measuring the reflectance at each wavelength at intervals of 1 nm including both ends in the wavelength range for calculating the average value.

In formula (I), Ma preferably contains at least one of Ca and ^Sr from the viewpoint of 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%.

The x, y, z and w in the formula (I) are not particularly limited as long as the above relational expressions are satisfied. Among them, x is preferably 0.7 or more and less than 1.0, and more preferably 0.8 or more and less than 1.0 from the viewpoint of crystal structure stability. Further, y is an activation amount of Eu, and may be appropriately selected so as to achieve a desired characteristic. For example, y preferably satisfies 0.002 ≦ y ≦ 0.020, and more preferably 0.005 ≦ y ≦ 0.015.

The nitride phosphor 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. By using an excitation light source in the wavelength range, it is possible to provide a phosphor having high luminous efficiency. In particular, it is 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 more preferable to use an excitation light source having a main emission peak wavelength at 420 nm or more and 460 nm or less.
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 not particularly limited, and is, for example, 45 nm or more.

Europium (Eu), which is a rare earth element, is the center of emission of the nitride phosphor. However, the emission center in this embodiment is not limited to europium, and a part thereof may be replaced with another rare earth metal or alkaline earth metal and co-activated with Eu. Eu ²⁺ , which is a divalent rare earth ion, exists stably if an appropriate mother body is selected, and has an effect of emitting light.

The average particle size of the nitride phosphor is not particularly limited and can be appropriately selected depending on the purpose and the like. From the viewpoint of luminous efficiency, the average particle size of the nitride phosphor 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 larger the average particle size, the higher the absorption rate and luminous efficiency of the excitation light tend to be. As described above, by including the nitride phosphor having excellent optical characteristics in the light emitting device described later, the luminous efficiency of the light emitting device is further improved.
Further, it is preferable that the nitride fluorescent substance frequently contains fluorescent particle particles having the above average particle size value. That is, it is preferable that the particle size distribution is distributed in a narrow range. By using a phosphor having a small variation in particle size distribution, a light emitting device having better color tone can be obtained by suppressing color unevenness.

In the present specification, the average particle size of the nitride fluorescent substance and other fluorescent substances is a numerical value called Fisher Sub Sieve Sizer's No., and is measured by using an air permeation method. Will be done. Specifically, in an environment with a temperature of 25 ° C and a humidity of 70%, a sample of 1 cm and ³ minutes is measured, packed in a dedicated tubular container, dried air at a constant pressure is flowed, and the specific surface area is read from the differential pressure. , It is a value converted into an average particle size.

The nitride fluorophore preferably has a structure having high crystallinity at least in part. For example, the vitreous (amorphous) has an irregular structure and low crystallinity, so if the reaction conditions in the production process cannot be controlled to be strictly uniform, the component ratio in the phosphor will not be constant. , Tends to cause uneven chromaticity, etc. On the other hand, the nitride phosphor according to the present embodiment tends to be easy to manufacture and process because it is a powder or a granular material having a structure having a high crystallinity at least partially. Further, since the nitride phosphor can be easily dispersed uniformly in an organic medium, it is possible to easily prepare a luminescent plastic, a polymer thin film material, and the like. Specifically, the nitride phosphor has a structure in which, for example, 50% by weight or more, more preferably 80% by weight or more, has crystallinity. This indicates the ratio of the crystal phase having luminescence, and it is preferable to have a crystal phase of 50% by weight or more because luminescence that can withstand practical use can be obtained. Therefore, the more crystal phases there are, the better the luminous efficiency. As a result, the emission brightness can be further increased and processing can be facilitated.

(Manufacturing method of nitride phosphor)
The production method of the present embodiment is a method for producing a nitride phosphor having a composition represented by the following formula (I), in which a raw material mixture is prepared at a temperature of 1000 ° C. or higher and 1300 ° C. or lower and a pressure of 0.2 MPa or higher and 200 MPa. A method for producing a nitride phosphor, which comprises treating in an atmosphere containing the following nitrogen gas.
M ^a _w M ^b _x Eu _y Al ₃ 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. Yes, w, x, y and z are 0.8 ≦ w <1.0, 0.5 ≦ x <1.0, 0.001 <y ≦ 0.1, z = (2/3) w +, respectively. Satisfy (1/3) x + (2/3) y + 3.

By heat-treating the raw material mixture at a predetermined temperature under a pressurized atmosphere containing nitrogen gas, a nitride phosphor having a desired composition and excellent luminous efficiency can be efficiently produced. Further, the produced nitride phosphor tends to have a reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) of 2 or more to a reflectance at 460 nm, and an average reflectance ratio (R ^640-660 /). R ^450-470 ) tends to be 2 or more, and better light emission efficiency can be achieved. Further, a nitride phosphor having an average particle size of 4.0 μm or more can be easily and efficiently produced.
The manufacturing method of the present embodiment can be applied to the above-described method for manufacturing a nitride phosphor according to the present embodiment. That is, the nitride phosphor produced by the production method of the present embodiment can be provided with the aspect of the nitride phosphor.

The composition of the raw material mixture used in the method for producing a nitride phosphor is not particularly limited as long as the composition represented by the formula (I) can be achieved. The raw material mixture can contain, for example, at least one selected from the group consisting of simple substances of metal elements constituting the composition represented by the formula (I) and metal compounds thereof. Examples of the metal compound include hydrides, nitrides, fluorides, oxides, carbonates, chlorides and the like, and are selected from the group consisting of hydrides, nitrides and fluorides from the viewpoint of light emission characteristics. It is preferable that the amount is at least one. 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.
Among them, the raw material mixture is 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, and a metal compound containing Al. And Eu, it is preferable to contain at least one metal compound selected from the group consisting of metal compounds including Eu.

Specifically, as a metal compound containing a metal element selected from the group consisting of Ca, Sr, Ba and Mg (hereinafter, also referred to as “first metal compound”), SrN ₂ , SrN, Sr ₃ N ₂ , SrH ₂ , SrF ₂ , Ca ₃ N ₂ , CaH ₂ , CaF ₂ , 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 selected from the group consisting of Li, Na and K (hereinafter, also referred to as “second metal compound”) preferably contains at least Li, and at least the nitride and hydride of Li. It is more preferable that it is one kind. 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 may be Ga and Ga of a group III element. It may be a metal compound substituted with a metal element selected from the group consisting of In and V, Cr, Co, etc., and may contain other metal elements constituting a nitride phosphor such as Li in addition to Al. It may be a metal compound.
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.

The metal compound containing Eu (hereinafter, also referred to as “fourth metal compound”) contains Eu as an activator, but a part of Eu is Sc, Y, La, Ce, Pr, Nd, Sm, Gd, It may be substituted with Tb, Dy, Ho, Er, Tm, Yb, Lu or the like. 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 color tone can be changed and 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 nitride fluorophore of 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 at least one selected from the group consisting of these is preferable. The nitride fluorophore according to 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 can be used to form a raw material mixture. can.

The raw material mixture may contain other metal elements, if necessary, in addition to the above-mentioned elemental metal elements and metal compounds. 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 compound in advance.

In addition, the nitride fluorophore according to the present embodiment may contain a small amount of oxygen in its composition. Oxygen is derived from various oxides used as raw material compounds; trace oxides contained in nitrides, metals, etc.; oxides produced by oxidation of raw material compounds during heat treatment; deposits on the nitride phosphor after formation. And so on.
In general, by controlling the molar ratio of oxygen in the nitride phosphor composition, it is possible to change the crystal structure of the phosphor and shift the emission peak wavelength of the phosphor. However, on the other hand, from the viewpoint of luminous efficiency, it is preferable that the amount of oxygen contained in the nitride phosphor is small. When the nitride phosphor contains an oxygen atom, the content thereof is, for example, 6% by mass or less.

The raw material mixture may contain a flux such as a halide. When the raw material mixture contains a flux, the reaction between the raw materials is further promoted, and further, the solid phase reaction proceeds more uniformly, so that a phosphor having a large particle size and excellent emission characteristics can be obtained. It is considered that this is because, for example, the heat treatment in the production method 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, the element ratio of cations can be added as a compound having a target composition, or the flux can be added in the form of being added after each raw material is added to the target composition.
When the raw material mixture contains a flux, the content thereof is, for example, 10% by mass or less, preferably 5% by mass or less in the raw material mixture. The content thereof is, for example, 2% by mass or more.

Next, among the nitride phosphors having the composition represented by the formula (I), a method for producing Sr _0.993 Eu _0.007 LiAl ₃ N ₄ as a design composition will be specifically described. The manufacturing method of is not limited to this.

As the metal compound constituting the raw material mixture, powders of SrN _x (equivalent to x = _2/3 ), Li 3N, AlN, and EuF ₃ were used, and the powders were used as Sr: Eu: Li: Al = 0.993: 0. The raw material mixture is obtained by weighing and mixing in a glove box having an inert atmosphere so as to be 007: 1.17: 3. Here, Li is easily scattered during firing, so it is blended in a larger amount than the theoretical value. The present embodiment is not limited to this composition ratio.

The above raw material mixture is heat treated in a nitrogen atmosphere. For the heat treatment, for example, a gas pressurized electric furnace can be used. The heat treatment temperature can be carried out 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. Further, as the heat treatment, a two-step firing (multi-step firing) is used in which the first step heat treatment is performed at 800 ° C. or higher and 1000 ° C. or lower, and the temperature is gradually raised to perform the second step heat treatment at 1000 ° C. or higher and 1400 ° C. or lower. You can also do it. For the heat treatment of 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 heat treatment 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 heat treatment atmosphere is preferably 70% by volume or more, more preferably 80% by volume or more.
The heat treatment 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.

The heat treatment time may be appropriately selected according to the heat treatment temperature, gas pressure, and the like. The heat treatment time is, for example, 1 to 10 hours, preferably 2 to 4 hours.

By the above heat treatment, a phosphor represented by Sr _0.993 Eu _0.007 LiAl ₃ N ₄ can be obtained. However, the composition of this nitride phosphor is a theoretical composition estimated from the blending ratio of the raw material mixture, and the coefficients of each element and scattered components such as F are excluded from the description. Since the actually synthesized composition contains oxygen derived from raw materials and the like, decomposition, scattering, etc. occur during heat treatment, the theoretical composition of the charged material is Sr, Eu, and Li when Al = 3. It may be less. Further, the composition of the target nitride phosphor can be changed by changing the blending ratio of each raw material.

Further, another manufacturing method other than the above is also possible. Specifically, a nitride phosphor may be produced by forming a raw material mixture using a hydride as a part of the above raw materials, and the metal alone of each element is weighed so as to have a predetermined composition ratio. After melting to form an alloy, the alloy is crushed and the alloy is nitrided in a gas pressure sintering furnace, HIP furnace, etc. in a nitrogen gas atmosphere to produce a nitride phosphor having a target composition. May be good.

By the above manufacturing method, it is possible to obtain the desired nitride phosphor. Further, Eu is a rare earth element, and a part of Eu may be replaced with various rare earth elements. In addition to Eu, rare earth elements such as La, Ce, Gd, Tb, Dy, Ho, Er, Tm, and Lu may be used. It is also possible to use a nitride phosphor containing the above. As described above, a desired nitride fluorophore can be obtained.

A specific example of the data of the emission characteristics of the nitride phosphor according to the present embodiment will be described later, but the nitride phosphor according to the present embodiment can be obtained by aiming at a specific composition while adopting specific synthetic conditions. It was confirmed that better emission characteristics could be achieved.

(Light emitting device)
Next, a light emitting device using the above-mentioned nitride phosphor as a component of the wavelength conversion member will be described. The light emitting device of the present embodiment includes a first phosphor containing the nitride phosphor and an excitation light source that emits light in a wavelength range of 400 nm or more and 570 nm or less.

A light emitting element can be used as the excitation light source. The light emitting element emits light in a wavelength range of 400 nm or more and 570 nm or less. The emission peak wavelength of the light emitting element is preferably in the wavelength range of 420 nm or more and 460 nm or less. By using a light emitting element having a emission peak wavelength in this range as an excitation light source, it is possible to construct a light emitting device that emits a mixed color light of light from the light emitting element and fluorescence from a phosphor. Further, since the light radiated from the light emitting element to the outside can be effectively used, the loss of the light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be obtained.

The half width of the emission spectrum of the emission element is not particularly limited. The full width at half maximum 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 that emits light in blue, green, or the like using a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1). Can be used.

The first phosphor contained in the light emitting device includes the above-mentioned nitride phosphor. 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 to the reflectance at 460 nm is 2 or more. The details of the nitride fluorophore are as described above, and the preferred embodiment is also the same. The first fluorophore is a red-emitting phosphor containing at least one of the nitride phosphors.

The first phosphor can be contained in, for example, a sealing resin 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 resin 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. Therefore, the loss of light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be provided.
The content of the first phosphor contained in the light emitting device is not particularly limited and can be appropriately selected depending on the excitation light source and the like. For example, the content of the first phosphor can be 1 to 50 parts by mass with respect to 100 parts by mass of the sealing resin, and is preferably 2 to 30 parts by mass.

The light emitting device may include a second phosphor having a emission peak wavelength different from that of the first phosphor. For example, in a light emitting device, by using a light emitting element that emits blue light and a first phosphor and a second phosphor excited by the light emitting element, white light having excellent color reproduction range and color rendering property can be obtained. Can be done.

As the second fluorescent substance, for example, a fluorescent substance having a composition represented by any of the following formulas (IIa) to (IIh) 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 the fluorescent substance having, and more preferably to contain at least one kind of the fluorescent substance having the composition represented by the formula (IIc) or (IIe).
(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)
In the composition formula (IIc), p preferably satisfies 0.01 <p <2.
The light emitting device may contain the second phosphor alone or in combination of two or more.

The average particle size of the second phosphor is not particularly limited and can be appropriately selected depending on the purpose and the like. 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, from the viewpoint of luminous efficiency.

The content of the second phosphor can be appropriately selected depending on the purpose and the like. For example, the content of the second phosphor can be 1 to 200 parts by weight with respect to 100 parts by weight of the sealing resin, and is preferably 2 to 180 parts by weight.

The content ratio of the first phosphor to the second phosphor is not particularly limited as long as the desired emission characteristics can be obtained, and can be appropriately selected depending on the intended purpose and the like. For example, the content ratio of the first fluorescent substance to the second fluorescent substance (first fluorescent substance / second fluorescent substance) can be 0.01 to 5 on a weight basis, and 0.05 to 3 is set. preferable.

It is preferable that the first fluorescent substance and the second fluorescent substance (hereinafter, also simply referred to as “fluorescent material”) form a sealing material for coating the light emitting element together with the sealing resin. Examples of the sealing resin constituting the sealing material include thermosetting resins such as epoxy resin, silicone resin, epoxy-modified silicone resin, and modified silicone resin.
The total content of the fluorescent substance in the encapsulating material is not particularly limited and can be appropriately selected depending on the purpose and the like. The total content of the phosphor can be, for example, 5 to 300 parts by mass, preferably 10 to 250 parts by mass, more preferably 15 to 230 parts by mass, and 15 to 200 parts by mass with respect to 100 parts by mass of the sealing resin. Parts by mass are more preferred. When the content of the phosphor in the encapsulating material is within the above range, the light emitting element can be sufficiently covered, and the light emitted from the light emitting element can be efficiently wavelength-converted by the phosphor, more efficiently. It can emit light.

The sealing material may further contain a filler, a light diffusing material, and the like in addition to the sealing resin and the phosphor. Examples of the filler include silica, titanium oxide, zinc oxide, zirconium oxide, alumina and the like.
When the sealing material 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 to 20 parts by mass with respect to 100 parts by mass of the sealing resin.

The type of the light emitting device is not particularly limited, and can be appropriately selected from the commonly used types. Examples of the type of light emitting device include a cannonball type and a surface mount type. Generally, the cannonball type refers to a cannonball-shaped shape of the resin constituting the outer surface. Further, the surface mount type refers to a type formed by filling a concave storage portion with a light emitting element and a resin as a light source. Further, as a type of light emitting device, a light emitting device as a light source is mounted on a flat plate-shaped mounting substrate, and a light emitting device in which a sealing resin containing a phosphor is formed in a lens shape or the like so as to cover the light emitting element or the like. Can also be mentioned.

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 40 having a recess, a light emitting element 10, and a sealing member 50 that covers the light emitting element 10. The light emitting element 10 is arranged in a recess formed in the package 40, and is electrically connected to a pair of positive and negative lead electrodes 20 and 30 arranged in the package 40 by a conductive wire 60. The sealing member 50 is filled in the recess and covers the light emitting element 10. The sealing member 50 further contains, for example, a sealing resin which is a thermosetting resin, and a first phosphor 71 and a second phosphor 72 that wavelength-convert the light from the light emitting element 10. A part of the positive and negative lead electrodes 20 and 30 is exposed on the outer surface of the package 40. The light emitting device 100 emits light by receiving electric power from the outside through these lead electrodes 20 and 30.

The sealing member 50 is formed by being filled with a translucent resin or glass so as to cover the light emitting element 10 placed in the recess of the light emitting device 100. Considering the ease of manufacture, the material of the sealing member is preferably a translucent resin. As the translucent resin, it is preferable to use a silicone resin composition, but an insulating resin composition such as an epoxy resin composition or an acrylic resin composition can also be used. Further, although the sealing member 50 contains the first fluorescent substance 71 and the second fluorescent substance 72, other materials may be further added as appropriate. 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.

The sealing member 50 functions not only as a member for protecting the light emitting element 10, the first phosphor 71 and the second phosphor 72 from the external environment, but also as a wavelength conversion member. In FIG. 1, the first phosphor 71 and the first phosphor 72 are partially unevenly distributed in the sealing member 50. By arranging the first phosphor 71 and the first phosphor 72 close to the light emitting element 10 in this way, the light from the light emitting element 10 can be efficiently wavelength-converted, and the luminous efficiency is excellent. It can be a luminous device. The arrangement of the sealing member 50 including the first phosphor 71 and the first phosphor 72 and the light emitting element 10 is not limited to the form in which they are arranged close to each other, and the first fluorescence Considering the influence of heat on the body 71 and the first phosphor 72, the light emitting element 10 and the first phosphor 71 and the first phosphor 72 are arranged at a distance in the sealing member 50. You can also do it. Further, by mixing the first fluorescent substance 71 and the first fluorescent substance 72 in the entire sealing member 50 at a substantially uniform ratio, it is possible to obtain light in which color unevenness is further suppressed.

Examples of applications of the light emitting device include, but are not limited to, lighting equipment, a backlight of a liquid crystal display, a display device such as a radar, and the like.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples.

(Example 1)
As a phosphor having a composition represented by M ^a _w M ^b _x Eu _y Al ₃ Nz, M ^a ₌ Sr, M ^b = Li, SrN _x (equivalent to x = 2/3), LiAlH ₄ , AlN, Gloves with an inert atmosphere using EuF ₃ as each raw material so that the molar ratio of the charged amount ratio is Sr: Li: Eu: Al = 0.993: 1.1: 0.007: 3. The raw material mixture was obtained by weighing and mixing in the box. Here, Li 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 1000 ° C., and the heat treatment was performed for 3 hours. A powder of the material phosphor was obtained.

(Example 2)
The nitride phosphor powder of Example 2 was obtained under the same conditions as in Example 1 except that the heat treatment temperature was changed to 1100 ° C.

(Example 3)
The nitride phosphor powder of Example 3 was obtained under the same conditions as in Example 1 except that the heat treatment temperature was changed to 1200 ° C.

(Example 4)
The nitride fluorophore powder of Example 4 was obtained under the same conditions as in Example 1 except that the heat treatment temperature was changed to 1300 ° C.

(Example 5)
In Example 1, the nitride phosphor powder of Example 5 was obtained under the same conditions as in Example 1 except that the amount of Li charged was increased and changed from 1.1 to 1.2.

(Example 6)
In Example 3, the nitride phosphor powder of Example 6 was obtained under the same conditions as in Example 3 except that the amount of Li charged was increased and changed from 1.1 to 1.2.

(Comparative Example 1)
The gas atmosphere is a mixed gas atmosphere of nitrogen (N ₂ ) / hydrogen (H ₂ ) = 9/1, the gas pressure is atmospheric pressure (gauge pressure 1.0 kPa, absolute pressure 0.10 MPa), and the temperature is 1000 ° C. The powder of the nitride phosphor of Comparative Example 1 was obtained under the same conditions as in Example 1 except that the heat treatment was carried out for 3 hours.

(Comparative Example 2)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 2 was obtained under the same conditions as in Comparative Example 1 except that the heat treatment temperature was changed to 1100 ° C.

(Comparative Example 3)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 3 was obtained under the same conditions as in Comparative Example 1 except that the heat treatment temperature was changed to 1200 ° C.

(Comparative Example 4)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 4 was obtained under the same conditions as in Comparative Example 1 except that the heat treatment temperature was changed to 1300 ° C.

(Comparative Example 5)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 5 was obtained under the same conditions as in Comparative Example 1 except that the gas atmosphere was changed to a nitrogen gas atmosphere.

(Comparative Example 6)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 6 was obtained under the same conditions as in Comparative Example 1 except that the gas atmosphere was changed to a nitrogen gas atmosphere and the heat treatment temperature was changed to 1100 ° C.

(Comparative Example 7)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 7 was obtained under the same conditions as in Comparative Example 1 except that the gas atmosphere was changed to a nitrogen gas atmosphere and the heat treatment temperature was changed to 1200 ° C.

(Comparative Example 8)
In Comparative Example 1, the nitride phosphor powder of Comparative Example 8 was obtained under the same conditions as in Comparative Example 1 except that the gas atmosphere was changed to a nitrogen gas atmosphere and the heat treatment temperature was changed to 1300 ° C.

<Evaluation>
(X-ray diffraction spectrum)
The X-ray diffraction spectrum (XRD) of the obtained nitride phosphor was measured. The measurement was carried out using Ultima IV manufactured by Rigaku and using CuKα ray. An example of the obtained XRD pattern is shown in FIG.
As shown in FIG. 2, it was confirmed that the compounds of Comparative Example 1, Example 1 and Example 2 were compounds represented by _SrLiAl 3N ₄ in composition.
In addition, in FIG. 2, in order from the bottom, the compound (SLAN) represented by _SrLiAl 3N ₄ shown for reference, the nitride fluorescent substance of Comparative Example 1, the nitride fluorescent substance of Example 1 and Example 2 The XRD pattern of the nitride phosphor is shown.

(Composition analysis)
For the obtained nitride phosphor, the composition ratio of each element of Sr, Li, Eu and Al was determined by ICP emission spectrometry. Table 1 shows the results of calculating the chemical composition ratio of each element from the Li amount ratio and Eu amount ratio at the time of charging and the obtained analytical values. The composition ratio of each element by composition analysis was determined with Al as the reference value 3.

(Average particle size)
The average particle size of the obtained nitride phosphor was measured. The average particle size of the obtained powder is F.I. S. S. S. No. (Fisher Sub Sieve Sizer's No.), which refers to the average particle size obtained by the air permeation method. Specifically, in an environment with a temperature of 25 ° C and a humidity of 70%, a sample of 1 cm and ³ minutes is measured, packed in a dedicated tubular container, dried air at a constant pressure is flowed, and the specific surface area is read from the differential pressure. , Converted to average particle size. The results are shown in Table 2.

(Light emission characteristics)
The emission characteristics of the obtained nitride phosphor were measured. The emission characteristics of the powder were measured with a spectrofluorometer: F-4500 (manufactured by Hitachi High-Technologies Corporation) with the wavelength of the excitation light set to 460 nm. The relative emission intensity (relative Ip:%), peak wavelength (λp: nm), and full width at half maximum (FWHM: nm) were obtained from the obtained emission spectrum. The results are shown in Table 2. The relative emission intensity was determined based on the nitride phosphor of Comparative Example 1.
Further, FIG. 3 shows the emission spectra of the nitride phosphors obtained in Comparative Examples 1 and 2 and Examples 1 to 3 as representatives of other Examples and Comparative Examples. The emission spectrum of FIG. 3 shows the relative emission intensity with respect to the wavelength.

(Reflectance)
The reflection spectrum of the obtained nitride phosphor was measured. The reflection spectrum was measured using a spectrofluorometer: F-4500 in the same manner as the emission characteristics. CaHPO ₄ was used as the standard of reflectance.
The reflectance was measured at 1 nm intervals in the measurement range. The average reflectance in the wavelength range of 450 nm or more and 470 nm or less was calculated as an arithmetic mean value by measuring the reflectance at 21 points of 450 nm or more and 470 nm or less. The average reflectance of 640 nm or more and 660 nm or less was calculated in the same manner.
The ratio of the reflectance at 650 nm to the reflectance at 460 nm (R ⁶⁵⁰ / R ⁴⁶⁰ ) and the ratio of the average reflectance at 640 nm or more and 660 nm or less (R ^640-660 / R ^450-470 ) to the average reflectance at 450 nm or more and 470 nm or less. I asked for each.
FIG. 4 shows the reflection spectra of the nitride phosphors obtained in Comparative Examples 1 and 2 and Examples 1 to 3 as representatives of other Examples and Comparative Examples.

The composition ratios shown in Table 1 are obtained with Al as the reference value 3. Looking at the results of the composition analysis, it can be seen that Li is less than the amount of the charged elements. Further, when the temperature becomes high, the amount of decrease in Li becomes large. On the other hand, in the examples, Sr and Li have numerical values close to the theoretical composition of SrLiAl ₃ N ₄ . Comparing the comparative example and the example, it can be seen that the decrease in Li is suppressed in the example in which the gas pressure (gauge pressure) is high. It can also be seen that Sr also tends to decrease in the comparative example, but the decrease is suppressed in the examples.

Table 2 shows the average particle size and light emission characteristics. It can be seen that the phosphors of Examples 1 to 6 have higher relative emission intensities than those of Comparative Examples 1 to 8 and are excellent in emission characteristics. The emission peak wavelength is 652 nm to 654 nm, and the half width is 55 nm to 61 nm. Further, the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) of the reflectance at 650 nm to the reflectance at 460 nm of Examples 1 to 6 is 2 or more, which is higher than that of Comparative Examples 1 to 8. The average reflectance ratio (R ^640-660 / R ^450-470 ) of the average reflectance of 40 nm or more and 660 nm or less (R ^640-660 ) to the average reflectance of 450 nm or more and 470 nm or less (R ^450-470 ) is also 2 or more. It has become.
As for the reflectance at 460 nm, the reflectance of Comparative Examples 1 to 4, 7 and 8 is larger than 35%, whereas the reflectance of Examples 1 to 6 is 35% or less, and the emission spectrum emits light near 460 nm. It can be seen that when it is used in a light emitting device provided with an excitation light source having a peak, it has high absorption of excitation light and has characteristics such as a particle size suitable for use.
The reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) is considered to indicate the ratio of the absorption of the excitation light in the nitride phosphor to the absorption at the emission wavelength. For example, if the nitride phosphor absorbs a large amount of light at the emission wavelength, even if the excitation light is absorbed and emitted, the amount of light emitted to the outside of the nitride phosphor is reduced. That is, when the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) is large, it is shown that the absorption of the excitation light is large and the absorption at the emission wavelength is small, which is an index of the luminous efficiency. The reason why the emission intensity becomes high and the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) becomes large is that the composition deviation is suppressed by increasing the high pressure during the heat treatment, and the crystal shape approaches a more ideal crystal shape. It is thought that it is influencing.
The average particle size of the phosphor particles of Examples 1 to 6 is 4 μm or more, which is larger than the average particle size of Comparative Examples 3, 4, 7, and 8. In particular, the average particle size of the phosphor particles of Examples 2 to 6 is larger than 4.5 μm, which is larger than the average particle size of Comparative Examples 1 to 8. As a result, it is considered that the relative emission intensity is further improved.

(Examples 7 to 10, Comparative Example 9)
In Example 2, the nitride phosphors of Examples 7 to 10 and Comparative Example 9 were set under the same conditions as in Example 2 except that the Li amount ratio and the Eu amount ratio at the time of charging were changed as shown in Table 3. Powders were obtained respectively. The Eu amount ratio was adjusted so that the total value with the Sr amount ratio would be 1 when Al was 3.
The obtained nitride phosphor powders of Examples 7 to 10 and Comparative Example 9 were evaluated in the same manner as described above. The composition ratios from the composition analysis are shown in Table 3, and the evaluation results of the emission characteristics are shown in Table 4.

As shown in Table 3, the Eu amount ratio obtained from the composition analysis was almost the same as the charged Eu amount ratio. The Li amount ratio and the Sr amount ratio obtained from the composition analysis were smaller than the charged amount ratio, and the Sr amount ratio was 0.900 to 0.958 and the Li amount ratio was 0.838 to 0.930.
As shown in Table 4, even in the nitride phosphors of Examples 7 to 9 in which the Eu amount ratio is changed, the relative emission intensity tends to be as high as that of Example 2, and the reflectance ratio (R ⁶⁵⁰ / R) tends to be as high as that of Example 2. It can be seen that ⁴⁶⁰ ) is also equal to or higher than that of Example 2. Further, although the nitride phosphor of Example 10 having an Eu amount ratio of 0.05, which is higher than that of Examples 2 and 7 to 9, the relative emission intensity is lower than that of Examples 2 and 7 to 9. , It can be seen that the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) is equivalent to that of Example 2 and higher than that of Comparative Example 9. On the other hand, the nitride phosphor of Comparative Example 9 having an Eu amount ratio of 0.001 lower than that of Examples 2 and 7 to 10 has a lower relative emission intensity than that of Examples 2 and 7 to 10 and reflects. The rate ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) is low.

(Example 11)
In Example 2, the nitride phosphor powder of Example 11 was obtained under the same conditions as in Example 2 except that a part of Sr was changed to Ca and the Eu amount ratio was further changed.
In Example 11, the raw material mixture was blended so that Sr: Ca: Li: Eu: Al = 0.891: 0.1: 1.2: 0.009: 3.0.
The obtained nitride fluorophore powder of Example 11 was evaluated in the same manner as described above. The composition ratios from the composition analysis are shown in Table 5, and the evaluation results of the emission characteristics are shown in Table 6.

(Example 12)
In Example 2, the nitride phosphor powder of Example 12 was obtained under the same conditions as in Example 2 except that a part of Sr was changed to Ba.
In Example 12, the raw material mixture was blended so as to have Sr: Ba: Li: Eu: Al = 0.893: 0.1: 1.1: 0.007: 3.0.
The obtained nitride fluorophore powder of Example 12 was evaluated in the same manner as described above. The composition ratios from the composition analysis are shown in Table 5, and the evaluation results of the emission characteristics are shown in Table 6.

As shown in the composition ratios from the composition analysis in Table 5, it can be seen that the nitride phosphors of Examples 11 and 12 contain Ca and Ba in addition to Sr. Further, as shown in Table 6, regarding the emission characteristics of the nitride phosphors of Examples 11 and 12, the relative emission intensity and the reflectance ratio (R ⁶⁵⁰ / R ⁴⁶⁰ ) are higher than those of the comparative examples as in the other examples. It can be seen that the light emission characteristics are high and excellent.

(Example A)
The light emitting device according to Example A has an LED having a light emitting peak wavelength of 453 nm, a nitride phosphor of Example 2 as a first phosphor, and β-sialon fluorescence having a light emitting peak wavelength of 544 nm as a second phosphor. It was prepared by a conventional method in combination with a body (Si _6-p Al _{p Op} N _8-p : Eu, 0 <p ≦ 4.2). The chromaticity of the mixed color emission of the light emitting device combining the blue LED and each phosphor was adjusted to the vicinity of x = 0.25 and y = 0.20 in the chromaticity coordinates (x, y).

(Comparative Example A)
The light emitting device according to Comparative Example A was produced by a usual method in the same manner as in Example A, except that the nitride phosphor of Comparative Example 2 was used as the first phosphor. Further, as in Example A, the chromaticity of the mixed color emission of the light emitting device was adjusted to the vicinity of the chromaticity coordinates.

Table 7 shows the chromaticity coordinates and the luminous flux ratio of the light emitting device according to Example A and Comparative Example A. The emission spectrum is shown in FIG. The emission spectrum of FIG. 9 shows the relative emission intensity with respect to the wavelength. The luminous flux of the light emitting device was measured using an integral total luminous flux measuring device, and is shown in the table below as a luminous flux ratio based on Comparative Example A.

As shown in Table 7, the luminous flux ratio of the light emitting device of Example A using the nitride phosphor of Example 2 is about 20% higher than that of Comparative Example A using the nitride phosphor of Comparative Example 2. rice field. As shown in FIG. 9, the emission spectrum had substantially the same spectral shape regardless of which nitride phosphor was used, but the relative emission intensity of Example A was higher than that of Comparative Example A.

(Example B)
The light emitting device according to Example B includes an LED having a emission peak wavelength of 455 nm, a nitride phosphor of Example 2 as the first phosphor, and Y ₃ (Al, Ga) ₅ O ₁₂ as the second phosphor. : Prepared by a usual method in combination with a fluorescent substance having a composition of Ce. The chromaticity of the mixed color emission of the light emitting device combining the blue LED and each phosphor was adjusted to the vicinity of x = 0.34 and y = 0.35 in the chromaticity coordinates (x, y).

(Comparative Example B)
The light emitting device according to Comparative Example B was produced by a usual method in the same manner as in Example B, except that the nitride phosphor of Comparative Example 2 was used as the first phosphor. Further, as in Example B, the chromaticity of the mixed color emission of the light emitting device was adjusted to the vicinity of the chromaticity coordinates.

Table 8 shows the chromaticity coordinates and the luminous flux ratio of the light emitting device according to Example B and Comparative Example B. The emission spectrum is shown in FIG. The emission spectrum of FIG. 10 shows the relative emission intensity with respect to the wavelength. The luminous flux of the light emitting device was measured using an integral total luminous flux measuring device, and is shown in the table below as a luminous flux ratio based on Comparative Example B.

As shown in Table 8, the luminous flux ratio of the light emitting device of Example B using the nitride phosphor of Example 2 is about 3% higher than that of Comparative Example B using the nitride phosphor of Comparative Example 2. rice field. Regarding the average color rendering index Ra, Example B was higher than Comparative Example B. As shown in FIG. 10, the emission spectrum had substantially the same spectral shape regardless of which phosphor was used, but the relative emission intensity of Example B was larger than that of Comparative Example B.

Since the nitride phosphor of the present embodiment has excellent luminous efficiency, it is possible to provide a light emitting device having a large luminous flux by using this nitride phosphor.

The light emitting device using the nitride phosphor of the present disclosure can be suitably used as a light source for lighting or the like. In particular, it can be suitably used for a light source for lighting, an LED display, a backlight source for liquid crystal, a signal device, a lighting switch, various sensors, various indicators, etc., which use a light emitting diode as an excitation light source and have extremely excellent light emission characteristics.

10: light emitting element, 50: sealing member, 71: first phosphor, 72: second phosphor, 100: light emitting device

Claims (13)

An element ^{Ma containing at least one selected from the group consisting of Ca, Sr, Ba and Mg, an element M b containing} at least one selected from the group consisting of Li, Na and K, Eu and Al. And N, including
With Al as 3, the element ^{Ma is contained in a molar ratio of 0.8 or more and less than 1, the element M b is} contained in a molar ratio of 0.5 or more, and Eu is contained in a molar ratio of 0.001 or more and 0.1 or less. A method for producing a nitride phosphor having ^a composition and having a theoretical composition represented by Ma M b ^Al 3 _N 4 _: Eu.
A raw material mixture in which the metal compound containing the element M ^b in the composition is mixed with Al as 3 so that the molar ratio of the element M ^b is 1.1 or more and 1.2 or less is prepared, and the temperature is 1000 ° C. or more. A method for producing a nitride phosphor, which comprises heat-treating the raw material mixture in an atmosphere containing nitrogen gas, which is 1400 ° C. or lower and the pressure is 0.2 MPa or more and 1.0 MPa or less as a gauge pressure. The nitride according to claim 1, wherein the raw material mixture contains at least one metal compound selected from the group consisting of hydrides, nitrides and fluorides, which comprises metal elements constituting the composition of the nitride phosphor. A method for producing a material phosphor. The method for producing a nitride phosphor according to claim 1 or 2, wherein the pressure is 0.8 MPa or more and 1.0 MPa or less as a gauge pressure. The nitride phosphor according to any one of claims 1 to 3, wherein the raw material mixture contains a nitride of the element ^{Ma, an aluminum hydride compound containing the element M b ,} aluminum nitride and europium fluoride. Production method. The method for producing a nitride phosphor according to any one of claims 1 to 4, wherein the temperature at which the raw material mixture is heat-treated is 1100 ° C. or higher and 1300 ° C. or lower. The method for producing a nitride fluorescent substance according to any one of claims 1 to 5, wherein the average particle size of the nitride fluorescent substance is 4.0 μm or more and 20 μm or less. The nitride according to any one of claims 1 to 6, wherein the nitride phosphor has an emission peak wavelength in the range of 630 nm or more and 670 nm or less when excited by light having a wavelength range of 400 nm or more and 570 nm or less. A method for producing a phosphor. The method for producing a nitride phosphor according to any one of claims 1 to 7, wherein the nitride phosphor has a ratio of a reflectance at 650 nm to a reflectance at 460 nm of 2 or more. The method for producing a nitride fluorescent substance according to any one of claims 1 to 8, wherein the nitride fluorescent substance has a reflectance of 30% or less at 460 nm. In the nitride phosphor, the element Ma contains at least one of Ca and Sr in ^a total molar ratio of 85 mol% or more of the element ^Ma , and the element M ^b contains Li as 80 of the element M ^b . The method for producing a nitride phosphor according to any one of claims 1 to 9, which has a composition containing a molar ratio of mol% or more. The nitride phosphor according to any one of claims 1 to 10 , wherein the raw material mixture contains a flux which is a compound selected from a rare earth metal, an alkaline earth metal and an alkali metal chloride or fluoride. Method. The method for producing a nitride phosphor according to claim 11 , wherein the content of the flux in the raw material mixture is 2% by mass or more and 10% by mass or less. The method for producing a nitride fluorescent substance according to any one of claims 1 to 12, wherein the nitride fluorescent substance has a composition represented by the following formula (I).
M ^a _w M ^b _x Eu _y Al ₃ 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 element selected from the group consisting of Li, Na and K, and w, x, y and z are 0.8 ≦ w <1.0, 0.5 ≦ x and 0.001 respectively. <y ≦ 0.1, z = (2/3) w + (1/3) x + (2/3) y + 3. )

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