WO2018056447A1 - Phosphor, light-emitting device, illumination device, and image display device - Google Patents

Abstract

A phosphor characterized by including a crystal phase represented by formula [2]. [2]: M_mAl_aO_xSi_bN_d (In formula [2], M represents an activating element, 0 < m ≤ 0.04, a + b = 3, 0 < a ≤ 0.08, 3.6 ≤ d ≤ 4.2, and x < a)

Description

Phosphor, light emitting device, lighting device, and image display device

The present invention relates to a phosphor, a light emitting device, a lighting device, and an image display device.

In recent years, with the trend of energy saving, the demand for lighting and backlights using LEDs is increasing. The LED used here is a white light emitting LED in which a phosphor is arranged on an LED chip that emits light of blue or near ultraviolet wavelength.
As such a type of white light emitting LED, a LED using a nitride phosphor that emits red light using blue light from the blue LED chip as an excitation light and a phosphor that emits green light on a blue LED chip has recently been used. It has been.
Especially in display applications, among these three colors of blue, green and red, green has a particularly high visual sensitivity to human eyes and contributes greatly to the overall brightness of the display. Therefore, development of a green phosphor that is particularly important and excellent in light emission characteristics is desired.
Examples of phosphors that emit green light include phosphors represented by a composition formula of Sr _2.7 Si ₁₃ Al ₃ O ₂ N ₂₁ : Eu _0.3 (Patent Document 1), and Si _6-z Al _z O. _{z N 8-z (0 <} z <4.2) phosphor represented by the composition of (Patent Document 2), comprising a sialon crystal in which Eu is solid-solved in crystal having a _β-Si 3 _{N 4} crystal structure A phosphor (Patent Document 3) and the like are disclosed.

International Publication No. 2012/124480 JP 2005-255895 A International Publication No. 2006/101095

Various phosphors have been developed as described above, but phosphors having excellent light emission characteristics are demanded.
In view of the above problems, the present invention provides a novel phosphor that has a crystal structure different from that of conventional phosphors, has good light emission characteristics, and is effectively used in LED applications.

In view of the above-mentioned problems, the present inventors diligently studied new phosphors. As a result, they arrived at the present invention by conceiving a new phosphor that is effectively used for LED applications and different from conventional phosphors.
The present invention is as follows.
[1]
A phosphor comprising a crystal phase represented by the following formula [2].
_{M m Al a O x Si b} N d [2]
(In the above formula [2],
M represents an activation element,
0 <m ≦ 0.04
a + b = 3
0 <a ≦ 0.08
3.6 ≦ d ≦ 4.2
x <a)
[2]
A phosphor comprising a crystal phase represented by the following formula [1].
M _m Al _a Si _b N _d [1]
(In the above formula [1],
M represents an activation element,
0 <m ≦ 0.04
a + b = 3
0 <a ≦ 0.08
3.6 ≦ d ≦ 4.2)
[3]
In [1] or [2], the M element in the formula [1] or [2] is a sialon crystal in which Eu is dissolved in a crystal having a β-type Si ₃ N ₄ crystal structure. The phosphor described.
[4]
The fluorescence according to any one of [1] to [3], which has an emission peak wavelength in a range of 500 nm to 560 nm by irradiating excitation light having a wavelength of 300 nm to 460 nm. body.
[5]
A first illuminant and a second illuminant that emits visible light when irradiated with light from the first illuminant, wherein the second illuminant is any one of [1] to [4] A light emitting device comprising the phosphor described above.
[6]
An illumination device comprising the light-emitting device according to [5] as a light source.
[7]
An image display device comprising the light-emitting device according to [5] as a light source.

The novel phosphor of the present invention has a crystal structure different from that of conventional phosphors and is excellent in light emission characteristics, so that it is effectively used for LED applications.
Therefore, the light emitting device using the novel phosphor of the present invention is excellent in color rendering. Furthermore, the illumination device and the image display device including the light emitting device of the present invention are of high quality.

It is an image by the scanning electron microscope of the fluorescent substance obtained in Example 1 (drawing substitute photograph). FIG. 3 is a diagram showing excitation / emission spectra of the phosphor obtained in Example 1. The broken line represents the excitation spectrum, and the solid line represents the emission spectrum. It is a figure which shows the powder X-ray-diffraction (XRD) pattern of the fluorescent substance obtained in Example 3, 4, 5, 7. It is a figure which shows the emission spectrum of the fluorescent substance obtained in Example 2, 3, 5, 7. It is a figure which shows the emission spectrum of the fluorescent substance obtained in Example 4, 8.

Hereinafter, the present invention will be described with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and examples, and may be arbitrarily modified without departing from the gist of the present invention. Can be implemented.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Further, in the phosphor composition formula in this specification, each composition formula is delimited by a punctuation mark (,). In addition, when a plurality of elements are listed separated by commas (,), one or two or more of the listed elements may be included in any combination and composition. For example, the composition formula “(Ca, Sr, Ba) Al ₂ O ₄ : Eu” has “CaAl ₂ O ₄ : Eu”, “SrAl ₂ O ₄ : Eu”, and “BaAl ₂ O ₄ : Eu”. “Ca _1-x Sr _x Al ₂ O ₄ : Eu”, “Sr _1-x Ba _x Al ₂ O ₄ : Eu”, “Ca _1-x Ba _x Al ₂ O ₄ : Eu”, _{"Ca 1-x-y Sr x} Ba y Al 2 O 4: Eu " (. in the formula, 0 <x <1,0 <y <1,0 < a x + y <1) all the comprehensive It shall be shown in

The present invention includes the phosphor according to the first embodiment, the light emitting device according to the second embodiment, the illumination device according to the third embodiment, and the image display device according to the fourth embodiment.

[Phosphor]
The phosphor according to the first embodiment of the present invention includes a crystal phase represented by the following formula [1].
M _m Al _a Si _b N _d [1]
(In the above formula [1],
M represents an activation element,
0 <m ≦ 0.04
a + b = 3
0 <a ≦ 0.08
3.6 ≦ d ≦ 4.2)

M elements are europium (Eu), manganese (Mn), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium It represents one or more elements selected from the group consisting of (Er), thulium (Tm) and ytterbium (Yb). M preferably contains at least Eu, and more preferably Eu.

Further, a part of Eu may be substituted with at least one element selected from the group consisting of Ce, Pr, Sm, Tb, and Yb, and Ce is more preferable in terms of emission quantum efficiency.
That is, M is more preferably Eu and / or Ce, and more preferably Eu.

The ratio of Eu with respect to the entire activation element is preferably 50 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more.
Al represents aluminum. Al is another trivalent element that is chemically similar, for example, boron (B), gallium (Ga), indium (In), scandium (Sc), yttrium (Y), lanthanum (La), gadolinium (Gd ), Lutetium (Lu) or the like.

Si represents silicon. Si may be partially substituted with other chemically similar tetravalent elements such as germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), and hafnium (Hf). Good.

In the formula [1], N represents a nitrogen element. N may be partially substituted with other elements such as oxygen (O), halogen atoms (fluorine (F), chlorine (Cl), bromine (Br), iodine (I)) and the like.

In addition, when oxygen is mixed as an impurity in the raw material metal, it may be introduced during a manufacturing process such as a pulverization process or a nitriding process, and is inevitably mixed in the phosphor of this embodiment. It is.
In addition, when halogen atoms are included, it may be mixed as an impurity in the raw material metal or introduced during a manufacturing process such as a pulverization process or a nitriding process. In particular, when a halide is used as a flux, a phosphor May be included.
m represents the content of the activating element M, the range is usually 0 <m ≦ 0.04, and the lower limit is preferably 0.0001, more preferably 0.0005, and still more preferably 0.00. 001, more preferably 0.005, and the upper limit thereof is preferably 0.02, more preferably 0.01, and particularly preferably 0.005.

a represents the content of Al, the range is usually 0 <a ≦ 0.08, and the lower limit is preferably 0.0001, more preferably 0.001, and still more preferably 0.005. The upper limit is preferably 0.06, more preferably 0.04.
b represents the content of Si element.
The relationship between a and b is
a + b = 3
Meet.
d represents the content of N, and the range thereof is generally 3.6 ≦ d ≦ 4.2, and the lower limit is preferably 3.8, more preferably 3.9, and particularly preferably 3.95. The upper limit is preferably 4.1, more preferably 4.05.

Any content is in the above-described range, which is preferable in terms of good light emission characteristics of the obtained phosphor, particularly light emission luminance.

In the phosphor of this embodiment, even when oxygen is mixed, the crystal structure can be maintained by partially replacing Si—N in the crystal structure with Al—O. When Al is increased relative to Si, O can be introduced into the N site while maintaining the charge compensation relationship.

On the other hand, the phosphor of the present embodiment is characterized in that the composition contains no or very little oxygen. In this specification, the absence of oxygen contained in the composition means that oxygen is below the detection limit when the phosphor powder is subjected to elemental analysis using an EPMA or oxygen-nitrogen / hydrogen analyzer described later. It is synonymous with. Although it is not certain how the charge balance is compensated when the phosphor of this embodiment has a lower oxygen content than Al, some Al is paired with Eu and substituted, It may be possible to maintain a local balance by introducing defects.
In this case, Al / Eu is preferably 0.05 or more, more preferably 0.10 or more, further preferably 0.2 or more, still more preferably 0.5 or more, and particularly preferably 1.0 or more.

Another aspect of the phosphor of the present embodiment includes a phosphor characterized by including a crystal phase represented by the following formula [2].
_{M m Al a O x Si b} N d [2]
(In the above formula [2],
M represents an activation element,
0 <m ≦ 0.04
a + b = 3
0 <a ≦ 0.08
3.6 ≦ d ≦ 4.2
x <a)

In the formula, the values of M element, Al, Si, N, and m, a, b, and d are considered in the same manner as in formula [1].
x represents the content of oxygen (O), and the range thereof is not particularly limited, but it is preferable that x <a. That is, it is preferable that the content of O is smaller than that of Al. As described above, this means that a phosphor with reduced oxygen can be obtained by introducing Al into the crystal structure in a form other than Al—O. x is preferably 0.05 or less, more preferably 0.04 or less, further preferably 0.03 or less, still more preferably 0.01 or less, and particularly preferably an element using an EPMA or an oxygen-nitrogen / hydrogen analyzer. According to the analysis, O is below the detection limit and is not included in the composition formula (that is, x = 0). Therefore, x is preferably 0 or more, and the case of x = 0 corresponds to the above equation [1].
x / a is preferably 1.0 or less, more preferably 0.8 or less, still more preferably 0.6 or less, still more preferably 0.4 or less, particularly preferably 0.2 or less, and particularly preferably As described above, oxygen is below the detection limit by elemental analysis using EPMA or an oxygen-nitrogen-hydrogen analyzer, and is not included in the composition formula (ie, x / a = 0 because x = 0) That is.
In addition, if there are too many defects that can be generated due to a smaller amount of O than Al, a killer site may be formed and the light emission characteristics may be deteriorated. Therefore, x + d is preferably 3.6 or more, more preferably 3.7 or more, still more preferably 3.8 or more, still more preferably 3.9 or more, and particularly preferably 3.95 or more.

{Physical properties of phosphor}
[Crystal structure]
The crystal structure of the phosphor according to the present embodiment is preferably a crystal structure of a sialon crystal in which Eu is dissolved in a crystal having a β-type Si ₃ N ₄ crystal structure. As the Si ₃ N ₄ crystal structure, it is generally known that there are α-type and β-type, but the phosphor of this embodiment has a desired emission wavelength and half-value width due to being β-type. Since an emission peak is obtained, it is preferable.

[Lattice constant]
The lattice constant of the phosphor of this embodiment varies depending on the type of elements constituting the crystal, but is in the following range.
The a-axis lattice constant (lattice constant La) is usually in the range of 7.600 Å ≦ La ≦ 7.630 、, and the lower limit thereof is preferably 7.601 Å, more preferably 7.602 Å, and even more preferably 7.60 Å. The upper limit is preferably 603 Å, and more preferably 7.615 よ り.
The b-axis lattice constant (lattice constant Lb) is the same as the a-axis lattice constant.
The c-axis lattice constant (lattice constant Lc) is usually in the range of 2.90Å ≦ Lc ≦ 2.91Å, and the lower limit is preferably 2.903Å, more preferably 2.906Å, and the upper limit is It is preferably 2.909 mm, more preferably 2.908 mm, and even more preferably 2.907 mm.

In any case, if the value is within the above range, the phosphor according to the present embodiment is stably generated, and the generation of the impurity phase is suppressed, so that the emission luminance of the obtained phosphor is good.

[Unit cell volume]
In the phosphor of the present embodiment, the unit cell volume calculated from the lattice constant (V) is preferably, 145.30A ³ or more, more preferably 145.35A ³ or more, more preferably 145.40A ³ or more, preferably 146.50A ³ or less, more preferably 146.30A ³ or less, further preferably 146.10A ³ or less.
If the unit cell volume is too large or the unit cell volume is too small, the skeletal structure becomes unstable and impurities of another structure are produced as a by-product, which tends to cause a decrease in emission intensity and color purity.

[Space group]
The crystal system in the phosphor according to this embodiment is a hexagonal system.
The space group in the phosphor of the present embodiment is not particularly limited as long as the average structure statistically considered within a range that can be distinguished by single crystal X-ray diffraction shows a repetition period of the above length, but “International It is preferable to belong to No. 173 (P6 ₃ ) or No. 176 (P6 ₃ / m) based on “Tables for Crystallography (Third, Revised Edition), Volume A SPACE-GROUP SYMMETRY”.
Here, the lattice constant and the space group can be obtained according to a conventional method. If it is a lattice constant, the results of X-ray diffraction and neutron diffraction can be obtained by Rietveld analysis, and if it is a space group, it can be obtained by electron beam diffraction.

[Luminescent color]
The emission color of the phosphor of this embodiment is excited by light in the near ultraviolet region to the blue region having a wavelength of 300 nm to 500 nm by adjusting the chemical composition and the like, and is blue, blue green, green, yellow green, yellow, orange , Red, etc., and a desired emission color can be obtained.

[Emission spectrum]
The phosphor of this embodiment preferably has the following characteristics when an emission spectrum is measured when excited with light having a wavelength of 300 nm or more and 460 nm or less (in particular, a wavelength of 400 nm or 450 nm).
The phosphor of this embodiment has a peak wavelength in the above-described emission spectrum of usually 500 nm or more, preferably 510 nm or more, more preferably 520 nm or more. Moreover, it is 560 nm or less normally, Preferably it is 550 nm or less, More preferably, it is 545 nm or less.
It is preferable for it to be in the above-mentioned range since the obtained phosphor exhibits a good green color.

[Half width of emission spectrum]
In the phosphor of this embodiment, the half-value width of the emission peak in the above-mentioned emission spectrum is usually 70 nm or less, preferably 60 nm or less, and usually 25 nm or more, preferably 30 nm or more.
By being within the above range, it can be used for an image display device such as a liquid crystal display.
When used for widening the color reproduction range of the image display device without further reducing the color purity, the half-value width of the emission peak is preferably 50 nm or less, more preferably 48 nm or less, further preferably 45 nm or less, and 43 nm or less. Is particularly preferred.

[Intensity ratio in emission spectrum]
In the case of using the phosphor of the present embodiment in order to widen the color reproduction range without reducing the color purity in the image display device described above, the peak ratio of the emission spectrum is as follows in addition to the above-described half-value width range. It is good to be in the range.
When the intensity of 512 nm in the emission spectrum is P1, and the intensity of 525 nm is P2, the value of P1 / P2 is usually 0.1 or more, preferably 0.3 or more, more preferably 0.5 or more, and further preferably It is 0.7 or more, more preferably 0.9 or more, particularly preferably 1.1 or more, and particularly preferably 1.3 or more, usually 3.0 or less, preferably 2.5 or less.

In addition, in order to excite the phosphor of this embodiment with light having a wavelength of 400 nm, for example, a GaN-based LED can be used. The measurement of the emission spectrum of the phosphor of this embodiment and the calculation of the emission peak wavelength, peak relative intensity, and peak half width are, for example, a 150 W xenon lamp as an excitation light source and a multi-channel CCD detector as a spectrum measurement device. It can be performed using a fluorescence measuring apparatus (manufactured by JASCO Corporation) equipped with C7041 (manufactured by Hamamatsu Photonics).

[CIE chromaticity coordinates]
The x value of the CIE chromaticity coordinate of the phosphor of this embodiment is usually 0.240 or more, preferably 0.250 or more, more preferably 0.260 or more, and usually 0.420 or less, preferably 0.400. In the following, it is more preferably 0.380 or less, further preferably 0.360 or less, and still more preferably 0.340 or less. Further, the y value of the CIE chromaticity coordinates of the phosphor of the present embodiment is usually 0.575 or more, preferably 0.580 or more, more preferably 0.620 or more, and further preferably 0.640 or more. It is 0.700 or less, preferably 0.690 or less.
When the CIE chromaticity coordinates are in the above range, the color reproduction range of the image display device can be widened without reducing the color purity when used in an image display device such as a liquid crystal display.

[Temperature characteristics (light emission intensity retention rate)]
The phosphor of this embodiment is also excellent in temperature characteristics. Specifically, the ratio of the emission peak intensity value in the emission spectrum at 150 ° C. to the emission peak intensity value in the emission spectrum at 25 ° C. when irradiated with light having a wavelength of 450 nm is usually 50%. Or more, preferably 60% or more, particularly preferably 70% or more.
In addition, since the emission intensity of ordinary phosphors decreases with increasing temperature, it is unlikely that the ratio exceeds 100%, but it may exceed 100% for some reason. However, if it exceeds 100%, there is a tendency to cause a color shift due to a temperature change.
Incidentally, when measuring the temperature characteristics, a conventional method may be followed, for example, a method described in JP-A-2008-138156.

[Excitation wavelength]
The phosphor of this embodiment has an excitation peak in a wavelength range of usually 300 nm or more, preferably 320 nm or more, more preferably 400 nm or more, and usually 480 nm or less, preferably 470 nm or less, more preferably 460 nm or less. That is, it is excited by light in the near ultraviolet to blue region.

<Method for producing phosphor>
The raw materials, the phosphor production method, and the like for obtaining the phosphor of this embodiment are as follows.
The method for producing the phosphor of the present embodiment is not particularly limited. For example, the element M as an activator (hereinafter referred to as “M source”) and the element Al (hereinafter referred to as “Al source” as appropriate). ), A raw material of elemental Si (hereinafter referred to as “Si source” as appropriate) is mixed so as to have a stoichiometric ratio of the formula [1] (mixing step), and the resulting mixture is fired (firing step). Can be manufactured.
In the following, for example, the raw material of the element Eu may be referred to as “Eu source”.

[Phosphor material]
Phosphor raw materials (that is, M source, Al source, and Si source) used for manufacturing the phosphor of this embodiment include metals, alloys, imide compounds, and acids of each element of M element, Al element, and Si element. Examples thereof include nitrides, nitrides, oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates, and halides. From these compounds, the reactivity to the composite oxynitride and the low generation amount of NOx, SOx, etc. during firing may be selected as appropriate.

(M source)
Of the M sources, specific examples of Eu sources include Eu ₂ O ₃ , Eu ₂ (SO ₄ ) ₃ , Eu ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O, EuCl ₂ , EuCl ₃ , Eu (NO _{3 ) 3 · 6H 2 O, EuN} , EuNH and the like. Of these, Eu ₂ O ₃ , EuN and the like are preferable, and EuN is particularly preferable.
In addition, as specific examples of raw materials of other activating elements such as Sm source, Tm source, Yb source, etc., compounds in which Eu is replaced with Sm, Tm, Yb, etc. in the respective compounds listed as specific examples of Eu source Is mentioned.

(Al source)
Specific examples of the Al source include AlN, Al ₂ O ₃ , Al (OH) ₃ , AlOOH, Al (NO ₃ ) _{3 and the} like. Among these, AlN and Al ₂ O ₃ are preferable, and AlN is particularly preferable. Moreover, as AlN, the thing with a small particle size from a reactive point and a high purity from the point of luminous efficiency is preferable.
The amount of oxygen contained in Al metal or AlN is usually 100 ppm or less, more preferably 50 ppm or less, and still more preferably 20 ppm or less.
Specific examples of other trivalent element materials include compounds in which Al is replaced with B, Ga, In, Sc, Y, La, Gd, Lu, etc. in each of the compounds listed as specific examples of the Al source. Can be mentioned. The Al source may be single Al.

(Si source)
Specific examples of the Si source include SiO ₂ , α-type Si ₃ N ₄ , and β-type Si ₃ N ₄ , and α-type Si ₃ N ₄ and β-type Si ₃ N ₄ are preferable. It is also possible to use a compound as a SiO _2. Specific examples of such a compound include SiO ₂ , H ₄ SiO ₄ , Si (OCOCH ₃ ) _{4 and the} like. Further, α-type Si ₃ N ₄ is preferably one having a small particle diameter and high purity from the viewpoint of light emission efficiency from the viewpoint of reactivity. Furthermore, the thing with few content rates of the carbon element which is an impurity is preferable.
In order to reduce the oxygen content in the product, it is preferable to use a Si source having a lower oxygen content. Si metal may be used, or Si ₃ N ₄ having a low oxygen content may be used. The oxygen content in α-type Si ₃ N ₄ and β-type Si ₃ N ₄ is usually 100 ppm or less, preferably 80 ppm or less, more preferably 60 ppm or less, still more preferably 40 ppm or less, and particularly preferably 20 ppm or less. It is more preferable to use α-type Si ₃ N ₄ having a high oxygen content after performing heat treatment at 1.0 MPa or lower and 1600 ° C. or higher to obtain β-type Si ₃ N ₄ having a low oxygen content.
Specific examples of other raw materials for tetravalent elements include compounds in which Si is replaced by Ge, Ti, Zr, Hf, etc. in the respective compounds listed as specific examples of the Si source. The Si source may be single Si.

In addition, each of the above-described M source, Al source, and Si source may be used alone or in combination of two or more in any combination and ratio.

[Mixing process]
Weigh the phosphor materials so that the desired composition is obtained, mix them well using a ball mill, etc., fill them in a crucible, fire them under a predetermined temperature and atmosphere, and pulverize and wash the fired product. The phosphor of the aspect can be obtained.

The mixing method is not particularly limited, and may be either a dry mixing method or a wet mixing method.
Examples of the dry mixing method include a ball mill.
As the wet mixing method, for example, a solvent or dispersion medium such as water is added to the above-described phosphor raw material, mixed using a mortar and pestle, and in a solution or slurry state, spray drying, heat drying, Alternatively, it is a method of drying by natural drying or the like.

[Baking process]
The obtained mixture is filled in a heat-resistant container such as a crucible or a tray made of a material having low reactivity with each phosphor raw material. The material of the heat-resistant container used at the time of firing is not particularly limited as long as the effects of the present embodiment are not impaired, and examples thereof include a crucible such as boron nitride.

Although the firing temperature varies depending on other conditions such as pressure, the firing can be usually performed in a temperature range of 1700 ° C. or higher and 2150 ° C. or lower. The maximum temperature reached in the firing step is usually 1700 ° C. or higher, preferably 1750 ° C. or higher, and usually 2150 ° C. or lower, preferably 2100 ° C. or lower.
If the calcination temperature is too high, nitrogen will fly and tend to produce defects in the host crystal and color, while if it is too low, the progress of the solid phase reaction will tend to be slow, making it difficult to obtain the target phase as the main phase. .
In the case where oxygen mixed in the crystal structure is further reduced, the firing is preferably performed at a maximum attained temperature of 1800 ° C. or higher, more preferably 1900 ° C. or higher, and particularly preferably 2000 ° C. or higher.

Although it varies depending on the firing temperature or the like, it is usually 0.2 MPa or more, preferably 0.4 MPa or more, and is usually 200 MPa or less, preferably 190 MPa or less.

When firing at a pressure of 10 MPa or less in the firing step, the highest temperature reached during firing is usually 1800 ° C. or higher, preferably 1900 ° C. or higher, and usually 2150 ° C. or lower, more preferably 2100 ° C. or lower.
By baking at the above temperature, a crystal phase with a low oxygen content can be obtained. When the firing temperature is less than 1800 ° C., the solid phase reaction does not proceed, so that only the impurity phase or the unreacted phase appears, and it may be difficult to obtain the target phase as the main phase.

In addition, even if a very small target crystal phase is obtained, there is a possibility that the element that becomes the luminescence center, particularly the Eu element, is not diffused in the crystal and the quantum efficiency is lowered. If the firing temperature is too high, the elements constituting the target phosphor crystal are likely to volatilize, and there is a high possibility that another phase will be formed as an impurity by forming or decomposing lattice defects.

The heating rate in the firing step is usually 2 ° C./min or more, preferably 5 ° C./min or more, more preferably 10 ° C./min or more, and usually 30 ° C./min or less, preferably 25 ° C./min or less. It is. If the rate of temperature rise is below this range, the firing time may be long. In addition, if the rate of temperature rise exceeds this range, the firing device, container, etc. may be damaged.

The firing atmosphere in the firing step is arbitrary as long as the phosphor of this embodiment is obtained, but a nitrogen-containing atmosphere is preferable. Specific examples include a nitrogen atmosphere and a hydrogen-containing nitrogen atmosphere, and a nitrogen atmosphere is particularly preferable. The oxygen content in the firing atmosphere is usually 10 ppm or less, preferably 5 ppm or less.

Calcination time varies depending on the temperature and pressure at the time of calcination, but is usually 10 minutes or more, preferably 30 minutes or more, and usually 72 hours or less, preferably 12 hours or less. If the firing time is too short, grain formation and grain growth cannot be promoted, so that a phosphor with good characteristics cannot be obtained. If the firing time is too long, volatilization of the constituent elements is promoted, so atomic deficiency As a result, defects may be induced in the crystal structure and a phosphor having good characteristics may not be obtained.

In addition, you may repeat a baking process in multiple times as needed. In that case, the firing conditions may be the same or different between the first firing and the second firing.

When the phosphor is uniformly diffused when the phosphor is produced and the phosphor having a high internal quantum efficiency is fired or when obtaining a large particle of several μm, repeated firing is effective.

Moreover, when manufacturing the phosphor of the present embodiment, during the firing step, for example, Li ₃ N, Na ₃ N, Mg ₃ N ₂ , Ca ₃ N ₂ , Sr ₃ N ₂ , Ba ₃ N _{2 and the} like are fluxed. It is preferably used as (crystal growth aid).
When a phosphor is manufactured using a flux, constituent elements of the flux such as Li, Na, Mg, Ca, Sr, and Ba may be mixed into the phosphor.
The flux in this embodiment preferably has an effect of reducing the proportion of oxygen in the obtained phosphor in addition to the effect as the crystal growth aid. In addition to the effect of growing crystals, it is possible to produce a phosphor with a narrow half-width of the emission spectrum by reducing the proportion of oxygen in the phosphor.
In order to reduce the proportion of oxygen in the obtained phosphor, Si metal, Al metal, or the like may be used as a substance to be added.

Furthermore, in order to reduce the proportion of oxygen in the crystal phase, it is preferable to use a member that adsorbs the gas in order to trap a gas containing oxygen in a constituent element such as SiO generated during firing. In particular, a member made of C (carbon) is good, and a C-made felt or C-cube is preferably arranged in the vicinity of the BN crucible.

[Post-processing process]
The obtained fired product is pulverized, pulverized, and / or classified into a powder having a predetermined size. _Here, it is preferable to process as _{D 50} is less than about 30 [mu] m.
Specific examples of the treatment include a method of subjecting the synthesized product to sieve classification with an opening of about 45 μm, and passing the powder that has passed through the sieve to the next step, or the synthesized product to a general method such as a ball mill, a vibration mill, or a jet mill. The method of grind | pulverizing to a predetermined particle size using a grinder is mentioned. In the latter method, excessive pulverization not only generates fine particles that easily scatter light, but also generates crystal defects on the particle surface, which may cause a decrease in luminous efficiency.

Moreover, you may provide the process of wash | cleaning fluorescent substance (baked material) as needed. After the cleaning step, the phosphor is dried until it has no adhering moisture and is used. Further, if necessary, dispersion / classification treatment may be performed to loosen the aggregation.
Note that the phosphor of this embodiment may be formed by a so-called alloy method in which a constituent metal element is alloyed in advance and nitrided.

{Phosphor-containing composition}
The phosphor according to the first embodiment of the present invention can be used by mixing with a liquid medium. In particular, when the phosphor according to the first embodiment of the present invention is used for a light emitting device or the like, it is preferable to use the phosphor in a form dispersed in a liquid medium. What dispersed the fluorescent substance which concerns on 1st embodiment of this invention in the liquid medium as one embodiment of this invention is suitably with "the fluorescent substance containing composition which concerns on one embodiment of this invention", etc. Shall be called.

[Phosphor]
There is no restriction | limiting in the kind of fluorescent substance which concerns on the 1st embodiment of this invention contained in the fluorescent substance containing composition of this embodiment, It can select arbitrarily from what was mentioned above. Further, the phosphor according to the first embodiment of the present invention to be contained in the phosphor-containing composition of the present embodiment may be only one type, or two or more types may be used in combination in any combination and ratio. Also good. Furthermore, the phosphor-containing composition of the present embodiment may contain a phosphor other than the phosphor according to the first embodiment of the present invention as long as the effects of the present embodiment are not significantly impaired.

[Liquid medium]
The liquid medium used in the phosphor-containing composition of the present embodiment is not particularly limited as long as the performance of the phosphor is not impaired within the intended range. For example, any inorganic material and any material can be used as long as it exhibits liquid properties under the desired use conditions, suitably disperses the phosphor according to the first embodiment of the present invention, and does not cause an undesirable reaction. An organic material can be used, and examples thereof include a silicone resin, an epoxy resin, and a polyimide silicone resin.

[Content of liquid medium and phosphor]
The phosphor and the liquid medium content in the phosphor-containing composition of the present embodiment are arbitrary as long as the effects of the present embodiment are not significantly impaired, but for the liquid medium, the phosphor-containing composition of the present embodiment. The total amount is usually 50% by weight or more, preferably 75% by weight or more, and usually 99% by weight or less, preferably 95% by weight or less.

[Other ingredients]
In addition, you may make the fluorescent substance containing composition of this embodiment contain other components other than a fluorescent substance and a liquid medium, unless the effect of this embodiment is impaired remarkably. Moreover, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

{Light emitting device}
A second embodiment of the present invention is a light-emitting device including a first light emitter (excitation light source) and a second light emitter that emits visible light when irradiated with light from the first light emitter. The second luminous body contains the phosphor according to the first embodiment of the present invention. Here, any one of the phosphors according to the first embodiment of the present invention may be used alone, or two or more thereof may be used in any combination and ratio.

As the phosphor according to the first embodiment of the present invention, for example, a phosphor that emits green region fluorescence under irradiation of light from an excitation light source is used. Specifically, when constituting a light emitting device, the green phosphor in the first embodiment of the present invention preferably has an emission peak in a wavelength range of 500 nm or more and 560 nm or less.

As the excitation source, one having an emission peak in a wavelength range of less than 420 nm may be used.
Hereinafter, the phosphor according to the first embodiment of the present invention has a light emission peak in a wavelength range of 500 nm to 560 nm, and the first light emitter has a light emission peak in a wavelength range of 300 nm to 460 nm. Although the aspect of the light-emitting device when using is described, this embodiment is not limited thereto.

In the above case, the light-emitting device of this embodiment can be set as follows, for example.
That is, the first light emitter has a light emission peak in the wavelength range of 300 nm to 460 nm, and the first phosphor of the second light emitter has a light emission peak in the wavelength range of 500 nm to 560 nm. A phosphor having an emission peak in the wavelength range of 580 nm to 680 nm as the second phosphor of the second phosphor using at least one phosphor (the phosphor according to the first embodiment of the present invention). An embodiment using (red phosphor) can be employed.

(Red phosphor)
As a red fluorescent substance in said aspect, the following fluorescent substance is used suitably, for example.
Examples of the Mn-activated fluoride phosphor include K ₂ (Si, Ti) F ₆ : Mn, K ₂ Si _1-x Na _x Al _x F ₆ : Mn (0 <x <1),
Examples of sulfide phosphors include (Sr, Ca) S: Eu (CAS phosphor), La ₂ O ₂ S: Eu (LOS phosphor),
Examples of the garnet phosphor include (Y, Lu, Gd, Tb) ₃ Mg ₂ AlSi ₂ O ₁₂ : Ce,
Examples of nanoparticles include CdSe,
Examples of the nitride or oxynitride phosphor include (Sr, Ca) AlSiN ₃ : Eu (S / CASN phosphor), (CaAlSiN ₃ ) _1-x · (SiO ₂ N ₂ ) _x : Eu (CASON fluorescence). Body), (La, Ca) ₃ (Al, Si) ₆ N ₁₁ : Eu (LSN phosphor), (Ca, Sr, Ba) ₂ Si ₅ (N, O) ₈ : Eu (258 phosphor), ( Sr, Ca) Al _{1 + x} Si _4-x O _x N _7-x : Eu (1147 phosphor), M _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu (M is Ca, Sr, etc.) ( α-sialon phosphor), Li (Sr, Ba) Al ₃ N ₄ : Eu (where x is 0 <x <1)
Etc.
In particular, when used as an image display device having a wide color reproduction range, the half-value width of the emission spectrum of the red phosphor in the above embodiment is usually 90 nm or less, preferably 70 nm or less, more preferably 50 nm or less, and still more preferably. Is 30 nm or less, usually 5 nm or more, more preferably 10 nm or more. Among the above phosphors, it is preferable to use a Mn-activated fluoride phosphor or a SrLiAl ₃ N ₄ : Eu phosphor.

(Yellow phosphor)
In the above embodiment, if necessary, a phosphor having a light emission peak in the range of 550 to 580 nm (yellow phosphor) may be used.
For example, the following phosphors are preferably used as the yellow phosphor.
Examples of the garnet phosphor include (Y, Gd, Lu, Tb, La) ₃ (Al, Ga) ₅ O ₁₂ : (Ce, Eu, Nd),
Examples of the orthosilicate include (Ba, Sr, Ca, Mg) ₂ SiO ₄ : (Eu, Ce),
Examples of (acid) nitride phosphors include (Ba, Ca, Mg) Si ₂ O ₂ N ₂ : Eu (SION phosphor), (Li, Ca) ₂ (Si, Al) ₁₂ (O, N ₁₆ : (Ce, Eu) (α-sialon phosphor), (Ca, Sr) AlSi ₄ (O, N) ₇ : (Ce, Eu) (1147 phosphor), (La, Ca, Y) ₃ ( Al, Si) ₆ N ₁₁ : Ce (LSN phosphor)
Etc.
The phosphor is preferably a garnet phosphor, and most preferably a YAG phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce.

(Green phosphor)
In the above aspect, the green phosphor may include a phosphor other than the phosphor according to the first embodiment of the present invention. For example, the following phosphors are preferably used.
Examples of the garnet phosphor include (Y, Gd, Lu, Tb, La) ₃ (Al, Ga) ₅ O ₁₂ : (Ce, Eu, Nd), Ca ₃ (Sc, Mg) ₂ Si ₃ O _12. : (Ce, Eu) (CSMS phosphor),
Examples of the silicate phosphor include (Ba, Sr, Ca, Mg) ₃ SiO ₁₀ : (Eu, Ce), (Ba, Sr, Ca, Mg) ₂ SiO ₄ : (Ce, Eu) (BSS phosphor). ),
As the oxide phosphor, for example, (Ca, Sr, Ba, Mg) (Sc, Zn) ₂ O ₄ : (Ce, Eu) (CASO phosphor),
Examples of (acid) nitride phosphors include (Ba, Sr, Ca, Mg) Si ₂ O ₂ N ₂ : (Eu, Ce), Si _6-z Al _z O _z N _8-z : (Eu, Ce) (β-sialon phosphor) (0 <z ≦ 1), (Ba, Sr, Ca, Mg, La) ₃ (Si, Al) ₆ O ₁₂ N ₂ : (Eu, Ce) (BSON phosphor) ,
Examples of the aluminate phosphor include (Ba, Sr, Ca, Mg) ₂ Al ₁₀ O ₁₇ : (Eu, Mn) (GBAM phosphor).

[Configuration of light emitting device]
The light emitting device of this embodiment has a first light emitter (excitation light source) and uses at least the phosphor according to the first embodiment of the present invention as the second light emitter, The configuration is not limited, and a known device configuration can be arbitrarily employed.
Examples of the device configuration and the light emitting device include those described in Japanese Patent Application Laid-Open No. 2007-291352.
In addition, examples of the form of the light emitting device include a shell type, a cup type, a chip on board, a remote phosphor, and the like.

{Use of light emitting device}
The use of the light-emitting device according to the second embodiment of the present invention is not particularly limited and can be used in various fields where a normal light-emitting device is used, but has a wide color reproduction range and color rendering properties. In particular, it is particularly preferably used as a light source for illumination devices and image display devices.

[Lighting device]
A third embodiment of the present invention is an illumination device including the light emitting device according to the second embodiment of the present invention as a light source.
When the light-emitting device according to the second embodiment of the present invention is applied to a lighting device, the light-emitting device as described above may be appropriately incorporated into a known lighting device. For example, a surface emitting illumination device in which a large number of light emitting devices are arranged on the bottom surface of the holding case can be used.

[Image display device]
According to a fourth embodiment of the present invention, there is provided an image display device comprising the light emitting device according to the second embodiment of the present invention as a light source.
When the light emitting device according to the second embodiment of the present invention is used as a light source of an image display device, the specific configuration of the image display device is not limited, but it is preferably used with a color filter. For example, when the image display device is a color image display device using color liquid crystal display elements, the light emitting device is used as a backlight, a light shutter using liquid crystal, and a color filter having red, green, and blue pixels; By combining these, an image display device can be formed.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof.

<Measurement method>
[Luminescent characteristics]
The sample was packed in a copper sample holder, and the excitation emission spectrum and emission spectrum were measured using a fluorescence spectrophotometer FP-6500 (manufactured by JASCO). During the measurement, the slit width of the light-receiving side spectroscope was set to 1 nm and the measurement was performed. The emission peak wavelength (hereinafter sometimes referred to as “peak wavelength”) and the half width of the emission peak were read from the obtained emission spectrum.

[Chromaticity coordinates]
The chromaticity coordinates of the x, y color system (CIE 1931 color system) are obtained from the data in the wavelength region of 460 nm to 800 nm of the emission spectrum obtained by the above method, according to JIS Z8724. The chromaticity coordinates CIEx and CIEy in the prescribed XYZ color system were calculated.

[Elemental analysis by EPMA]
In order to examine the elements of the phosphor obtained in the first embodiment of the present invention, the following elemental analysis was performed. After selecting several crystals by observation with a scanning electron microscope (SEM), each element is analyzed using an electron probe microanalyzer (wavelength dispersive X-ray analyzer: EPMA) JXA-8200 (manufactured by JEOL). Carried out. In addition, the detection limit value of oxygen in this apparatus is 100 ppm.

[Elemental analysis by ICP]
The quantitative determination of Si, Al, Eu, and Mg may be replaced by the following ICP elemental analysis in addition to the EPMA elemental analysis.
The sample was melted with an alkali, dissolved by adding an acid, the obtained sample solution was appropriately diluted, and quantified with an inductively coupled plasma emission spectrometer iCAP7600 Duo (manufactured by Thermo Fisher Scientific). The measurement conditions are as follows.
RF power: 1200W
Nebulizer egas flow rate: 0.60 L / min
Coolant gas flow rate: 12L / min
Auxiliary gas: 1.0 L / min

[O, N quantification]
Quantification was performed with an oxygen-nitrogen-hydrogen analyzer (TCH600, manufactured by LECO) under an inert gas atmosphere using an impulse furnace heating extraction-NIR (O) detection method / TCD (N) detection method. The detection limit value of oxygen in this apparatus is 0.2% by weight, and about 0.1 g of sample was measured in the examples and comparative examples.

[Powder X-ray diffraction measurement]
Powder X-ray diffraction was precisely measured with a powder X-ray diffractometer D2 PHASER (manufactured by BRUKER). The measurement conditions are as follows.
Using CuKα tube X-ray output = 30 KV, 10 mA
Scanning range 2θ = 5 ° ~ 65 °
Reading width = 0.025 °

[Lattice constant refinement]
For the lattice constant, from the powder X-ray diffraction measurement data of each example, a peak due to a crystal structure in which the space group is classified as (P6 ₃ / m) (International Tables for Crystallography, No. 176) is extracted. It was determined by refining using the processing software TOPAS 4 (manufactured by Bruker).

{Manufacture of phosphor}
[Examples 1 to 7]
Using EuN, Si ₃ N ₄ , and AlN as phosphor materials, phosphors were prepared as follows.
The raw materials were weighed with an electronic balance so as to have the weights shown in Table 1 below, placed in an alumina mortar, and ground and mixed until uniform. Further, 1.00 g of Mg ₃ N ₂ (manufactured by Shellac Co.) was added as a flux to this mixed powder, and further pulverized and mixed. These operations were performed in a glove box filled with Ar gas.

About 0.5 g of the obtained raw material mixed powder was weighed and filled into a boron nitride crucible as it was. This crucible was placed in a vacuum pressure firing furnace (manufactured by Shimadzu Mectem Co.). Next, the pressure was reduced to 8 × 10 ⁻³ Pa or less, and then vacuum heating was performed from room temperature to 800 ° C. at a temperature rising rate of 20 ° C./min. When the temperature reached 800 ° C., nitrogen gas was introduced for 5 minutes while maintaining that temperature until the pressure in the furnace reached 0.85 MPa. After the introduction of nitrogen gas, the temperature in the furnace was further maintained at 0.85 MPa, and the temperature was further increased to 1600 ° C. and maintained for 1 hour. Furthermore, it heated to 1950 degreeC, and when it reached 1950 degreeC, it maintained for 4 hours. After firing, it was cooled to 1200 ° C. and then allowed to cool. Thereafter, the product was crushed to obtain phosphors of Examples 3 to 7. For Examples 1 and 2, after pulverizing the product, green crystals were selected to obtain phosphors of Examples 1 and 2.

The result of SEM observation of the phosphor of Example 1 is shown in FIG. In addition, the single crystal of Example 1 was selected from SEM observation, and elemental analysis (EPMA measurement) was performed in order to examine the constituent elements and their ratios. Elements detected in EPMA were Eu, Al, Si, and N, and magnesium and oxygen were below the detection limit. As a result of quantitative analysis, the atomic ratio of Eu: Al: Si was 0.016 (1): 0.048 (1): 2.95 (2). Numbers in parentheses represent standard deviation. It was confirmed that the mixing of oxygen during firing was almost zero.

Next, the single crystal structure analysis of Example 1 was implemented. As a result of the basic reflection obtained by single crystal X-ray diffraction, the crystal system of the phosphor of Example 1 is a hexagonal system, and the lattice constants are a = 7.6265 (4) Å, b = 7. .6265 (4) Å, c = 2.9075 (2) Å, α = 90 °, β = 90 °, γ = 120 °. Further, the unit cell volume of the phosphor of Example 1 was 146.454 ³ .

The excitation / emission spectrum of the phosphor of Example 1 is shown in FIG. The excitation spectrum is obtained by monitoring emission at 540 nm. The emission spectrum is a measurement result when excited at 450 nm. The phosphor of Example 1 showed an emission spectrum with an emission peak wavelength of 540 nm and a half width of 70 nm, and was confirmed to show green emission.

For the phosphors of Examples 2 and 3, single crystals of Examples 2 and 3 were selected from SEM observation, and EPMA composition analysis was performed. Elements detected in EPMA were Eu, Al, Si, and N as in Example 1, and magnesium and oxygen were below the detection limit. As a result of quantitative analysis, the atomic ratio of Eu: Al: Si was 0.008 (1): 0.039 (1): 2.96 (2) in Example 2, and was 0.8 in Example 3. 006 (1): 0.030 (1): 2.97 (2). Numbers in parentheses represent standard deviation. It was confirmed that the mixing of oxygen during firing was almost zero.

The phosphor of Example 4 was subjected to composition analysis by ICP and O / N analysis by an oxygen nitrogen hydrogen analyzer. As a result, oxygen was below the detection limit, and the atomic ratio of Eu: Al: Si was 0.003: 0.04: 2.96.
The powder X-ray diffraction patterns of the phosphors of Examples 3, 4, 5, and 7 are shown in FIG. Table 2 shows the lattice constants and unit cell volumes of the phosphors of Examples 2 to 7 refined from the obtained powder X-ray diffraction pattern. In Examples 2 to 7, phosphors having a structure similar to that of Example 1 were obtained in a substantially single phase.

The phosphor obtained according to the first embodiment of the present invention can change the ratio of Eu: Al: Si in the crystal to change the a-axis from 7.604 to 7.6265 and the c-axis from 2.906 to vary from 2.908A, accordingly, the unit cell volume was also found to vary from 145.53A ³ to 146.454Å ^3.
The emission spectra of the phosphors of Examples 2, 3, 5, and 7 when excited with light having a wavelength of 450 nm are shown in FIG. In addition, Table 3 shows the emission peak wavelength, the half width, and the chromaticity read from the emission spectrum when excited with light having a wavelength of 450 nm for the phosphors of Examples 2 to 7.

The phosphor obtained by the first embodiment of the present invention changes the Eu: Al: Si ratio in the crystal to change the emission peak wavelength in the emission spectrum from 513 nm to 540 nm, and the half width from 40 nm. It became clear that it was possible to change to 76 nm. That is, light emission of blue green to yellow green can be obtained by using an arbitrary composition.

[Example 8]
A phosphor was prepared as follows using Eu ₂ O ₃ , Si ₃ N ₄ , AlN, and Al ₂ O ₃ as phosphor materials.
As Si ₃ N ₄ , α-type Si ₃ N ₄ (manufactured by Ube Industries, Ltd .: SN-E10) was heat-treated at 1950 ° C. for 12 hours in a nitrogen atmosphere at a pressure of 0.92 MPa to make all β-type Si ₃ N ₄ It was used.
The raw materials were weighed with an electronic balance so as to have the respective weights shown in Table 4 below, placed in an alumina mortar, and ground and mixed until uniform in the air. In Example 8, magnesium nitride was not used.
About 2.0 g of the obtained raw material mixed powder was weighed and filled in a boron nitride crucible as it was. This crucible was placed in a vacuum pressure firing furnace (manufactured by Shimadzu Mectem Co.). Next, the pressure was reduced to 8 × 10 ⁻³ Pa or less, and then vacuum heating was performed from room temperature to 800 ° C. at a temperature rising rate of 20 ° C./min. When the temperature reached 800 ° C., nitrogen gas was introduced for 5 minutes while maintaining that temperature until the pressure in the furnace reached 0.85 MPa. After the introduction of nitrogen gas, the temperature in the furnace was further maintained at 0.85 MPa, and the temperature was further increased to 1600 ° C. and maintained for 1 hour. Furthermore, it heated to 2000 degreeC, and when it reached 2000 degreeC, it maintained for 4 hours. After firing, it was cooled to 1200 ° C. and then allowed to cool. Thereafter, the product was crushed to obtain the phosphor of Example 8.
Example 8 was all β-SiAlON single phase.

The composition analysis by ICP of Example 8 and the O / N analysis by an oxygen nitrogen hydrogen analyzer were performed. As a result, oxygen was detected, and the atomic ratio of Eu: Al: Si: O: N was 0.003: 0.05: 2.95: 0.04: 3.91.
The emission spectra of the phosphors of Example 4 and Example 8 when excited with light having a wavelength of 450 nm are shown in FIG. Table 5 shows the emission peak wavelength, half-value width, and chromaticity read from the emission spectrum when excited with light having a wavelength of 450 nm for the phosphors of Example 4 and Example 8.
It has been clarified that by reducing oxygen in the crystal structure, the emission peak wavelength is shortened and the half width is narrowed.

Claims (7)

1. A phosphor comprising a crystal phase represented by the following formula [2].
   _{M m Al a O x Si b} N d [2]
   (In the above formula [2],
   M represents an activation element,
   0 <m ≦ 0.04
   a + b = 3
   0 <a ≦ 0.08
   3.6 ≦ d ≦ 4.2
   x <a)
2. A phosphor comprising a crystal phase represented by the following formula [1].
   M _m Al _a Si _b N _d [1]
   (In the above formula [1],
   M represents an activation element,
   0 <m ≦ 0.04
   a + b = 3
   0 <a ≦ 0.08
   3.6 ≦ d ≦ 4.2)
3. The M element in the formula [1] or [2] is Eu, and is a crystal structure of a sialon crystal in which Eu is dissolved in a crystal having a β-type Si ₃ N ₄ crystal structure. Phosphor.
4. The fluorescence according to any one of claims 1 to 3, which has an emission peak wavelength in a range of 500 nm to 560 nm by irradiating excitation light having a wavelength of 300 nm to 460 nm. body.
5. A first light emitter and a second light emitter that emits visible light when irradiated with light from the first light emitter, the second light emitter according to any one of claims 1 to 4. A light emitting device comprising the phosphor described above.
6. An illumination device comprising the light-emitting device according to claim 5 as a light source.
7. An image display device comprising the light emitting device according to claim 5 as a light source.

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