JP6985704B2 - Fluorescent material, light emitting device, lighting device and image display device - Google Patents

Description

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

In recent years, due to the trend of energy saving, the demand for lighting and backlights using LEDs has been increasing. The LED used here is a white light emitting LED in which a phosphor is arranged on an LED chip that emits light having a blue or near-ultraviolet wavelength.
As such types of white light emitting LEDs, those using a nitride phosphor that emits red light as excitation light and a phosphor that emits green light on a blue LED chip have been used in recent years. Has been done.
In particular, in display applications, among these three colors of blue, green and red, green has particularly high luminosity factor for the human eye and greatly contributes to the overall brightness of the display, so it is compared with the other two colors. Therefore, it is particularly important to develop a green phosphor having excellent emission characteristics.
Examples of the phosphor that emits green light include a phosphor (Patent Document 1) represented by the composition formula of _{Sr 2.7} Si ₁₃ Al ₃ O ₂ N ₂₁ : Eu _{0.3 , and Si 6-z} Al _z O. Includes a phosphor (Patent Document 2) represented by a composition of _z N _8-z (0 <z <4.2), and a sialon crystal in which Eu is solid-dissolved in a crystal having _{a β-type Si 3} N _{4 crystal structure.} Fluorescent materials (Patent Document 3) and the like are disclosed.

International Publication No. 2012/12480 Japanese Unexamined Patent Publication No. 2005-255895 International Publication No. 2006/101095

As described above, various fluorescent materials have been developed, but a fluorescent material having excellent emission characteristics is required.
In view of the above problems, the present invention provides a novel phosphor having a crystal structure different from that of a conventional phosphor, having good emission characteristics, and being effectively used in LED applications.

In view of the above problems, the present inventors have diligently studied a new search for a fluorescent substance, and have arrived at a novel fluorescent substance different from the conventional fluorescent substance, which is effectively used for LED applications, and arrived at the present invention.
The present invention is as follows.
[1]
A fluorescent substance 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 active element and represents an active element.
0 <m ≤ 0.04
a + b = 3
0 <a ≤ 0.08
3.6 ≤ d ≤ 4.2
x <a)
[2]
A fluorescent substance 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 active element and represents an active 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 Eu, which is a crystal structure of a sialon crystal in which Eu is solid-dissolved in a crystal having _{a β-type Si 3} N _{4 crystal structure.} The described phosphor.
[4]
The fluorescence according to any one of [1] to [3], which has an emission peak wavelength in the range of 500 nm or more and 560 nm or less by irradiating with excitation light having a wavelength of 300 nm or more and 460 nm or less. body.
[5]
A first light emitting body and a second light emitting body that emits visible light by irradiation of light from the first light emitting body are provided, and the second light emitting body is one of [1] to [4]. A light emitting device comprising the above-mentioned fluorescent substance.
[6]
A lighting 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 the conventional phosphor 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 has excellent color rendering properties. Further, the lighting device and the image display device including the light emitting device of the present invention are of high quality.

It is an image of the phosphor obtained in Example 1 by a scanning electron microscope (photograph substitute for drawing). It is a figure which shows the excitation / emission spectrum of the fluorescent substance obtained in Example 1. FIG. The dashed 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 Examples 3, 4, 5 and 7. It is a figure which shows the emission spectrum of the fluorescent substance obtained in Examples 2, 3, 5 and 7. It is a figure which shows the emission spectrum of the fluorescent substance obtained in Examples 4 and 8.

Hereinafter, the present invention will be described with reference to embodiments and examples, but the present invention is not limited to the following embodiments and examples, and can be arbitrarily modified without departing from the gist of the present invention. Can be carried out.
In addition, the numerical range represented by using "~" in this specification means the range including the numerical values before and after "~" as the lower limit value and the upper limit value. Further, in the composition formula of the fluorescent substance in the present specification, the delimiter of each composition formula is represented by a comma (,). Further, when a plurality of elements are listed separated by a comma (,), it is indicated that one or more of the listed elements may be contained in any combination and composition. For example, the composition formula "(Ca, Sr, Ba) Al ₂ O ₄ : Eu" is "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", and "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 as shown in.

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

[Fluorescent material]
The fluorescent substance according to the first embodiment of the present invention contains 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 active element and represents an active element.
0 <m ≤ 0.04
a + b = 3
0 <a ≤ 0.08
3.6 ≤ d ≤ 4.2)

The M elements are europium (Eu), manganese (Mn), cerium (Ce), placeodim (Pr), neodym (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), formium (Ho), and erbium. Represents one or more elements selected from the group consisting of (Er), thulium (Tm) and itterbium (Yb). M preferably contains at least Eu, more preferably Eu.

Further, Eu may be partially 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 to the total active 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 chemically similar trivalent element such as boron (B), gallium (Ga), indium (In), scandium (Sc), yttrium (Y), lanthanum (La), gadolinium (Gd). ), Lutetium (Lu), etc. may be partially substituted.

Si represents silicon. Even if Si is partially substituted with other chemically similar tetravalent elements such as germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), hafnium (Hf) and the like. good.

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

It should be noted that oxygen may be mixed as an impurity in the raw metal, or may be introduced during a manufacturing process such as a pulverization step or a nitriding step, and is inevitably mixed in the phosphor of the present embodiment. Is.
Further, when a halogen atom is contained, it may be mixed as an impurity in the raw metal, or may be introduced during a manufacturing process such as a pulverization step or a nitriding step. In particular, when a halide is used as a flux, a phosphor is used. It may be included in it.
m represents the content of the activating element M, the range of which is usually 0 <m ≦ 0.04, and the lower limit is preferably 0.0001, more preferably 0.0005, still more preferably 0. 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 of which is usually 0 <a≤0.08, and the lower limit is preferably 0.0001, more preferably 0.001, and even more preferably 0.005. The upper limit is preferably 0.06, more preferably 0.04.
b represents the content of Si element.
The mutual relationship between a and b is
a + b = 3
Meet.
d represents the content of N, the range of which is usually 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.

When the content of any of them is in the above range, it is preferable that the emission characteristics of the obtained phosphor, particularly the emission brightness, are good.

The phosphor of the present embodiment can maintain its crystal structure by partially substituting Al—O for Si—N in the crystal structure even when oxygen is mixed. When the amount of Al is increased with respect to Si, O can be added to the N site while maintaining the charge compensation relationship.

On the other hand, the fluorescent substance of the present embodiment is characterized by having no or extremely little oxygen contained in the composition. In the present specification, the absence of oxygen contained in the composition means that the oxygen is below the detection limit when the powder of the phosphor is elementally analyzed by an EPMA or an oxygen-nitrogen hydrogen analyzer described later. Is synonymous with. It is not clear how the phosphor of this embodiment compensates for the charge balance when the oxygen content is lower than that of Al, but some Al is replaced with Eu in pairs. It is possible that the balance is maintained locally 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, further preferably 0.5 or more, and particularly preferably 1.0 or more.

As another embodiment of the fluorescent substance of this embodiment, there is a fluorescent substance characterized by containing 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 active element and represents an active 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, d can be considered in the same manner as in the formula [1].
x represents the content of oxygen (O), and the range thereof is not particularly limited, but x <a is preferable. That is, it is preferable that the content of O is smaller than that of Al. This means that, as described above, by introducing Al into the crystal structure in a form other than Al—O, it is possible to obtain a phosphor having reduced oxygen. x is preferably 0.05 or less, more preferably 0.04 or less, still more 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. By analysis, O is below the detection limit and is not included in the composition formula (ie, 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 much more preferably. Similarly to the 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 (that is, x / a = 0 because x = 0). That is.
Further, if too many defects are introduced due to the content of O being lower than that of Al, killer sites 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.

{About the physical characteristics of the fluorescent substance}
[Crystal structure]
The crystal structure of the phosphor of the present embodiment is preferably a crystal structure of a sialon crystal in which Eu is solid-dissolved in a crystal having _{a β-type Si 3} N _{4 crystal structure.} The Si ₃ N ₄ crystal structure, generally that there are α-type and β-type are known, in the phosphor of the present embodiment, by a β-type, having the desired emission wavelength and FWHM It is preferable because an emission peak can be obtained.

[Lattice constant]
The lattice constant of the phosphor of the present embodiment varies depending on the type of the element constituting the crystal, but is in the following range.
The lattice constant (lattice constant La) of the a-axis is usually in the range of 7.600 Å ≤ La ≤ 7.630 Å, and its lower limit is preferably 7.601 Å, more preferably 7.602 Å, and even more preferably 7. The upper limit is 603 Å, preferably 7.620 Å, and more preferably 7.615 Å.
The lattice constant of the b-axis (lattice constant Lb) is the same as the lattice constant of the a-axis.
The lattice constant of the c-axis (lattice constant Lc) is usually in the range of 2.90 Å ≤ Lc ≤ 2.91 Å, the lower limit is preferably 2.903 Å, more preferably 2.906 Å, and the upper limit is. It is preferably 2.909 Å, more preferably 2.908 Å, and even more preferably 2.907 Å.

In any case, when it is within the above range, the phosphor according to this embodiment is stably generated and the generation of the impurity phase is suppressed, so that the emission brightness 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, 145.30Å ³ or more, more preferably 145.35Å ³ or more, more preferably 145.40Å ³ or more, preferably 146.50Å ³ or less, more preferably 146.30Å ³ or less, further preferably 146.10Å 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 by-produced, which tends to cause a decrease in emission intensity and a decrease in 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 in a range distinguishable by single crystal X-ray diffraction shows the repetition period of the above length, but "International". It is preferable that it belongs to _{No. 173 (P6 3} ) or No. 176 (P6 ₃ / m) based on "Tables for Crystallography (Third, reproduced edition), Volume A SPACE-GROUP-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.

[Emission color]
The emission color of the phosphor of the present embodiment is excited by light in the near-ultraviolet region to the blue region such as 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, and orange. , Red, etc., can be a desired emission color.

[Emission spectrum]
The phosphor of this embodiment preferably has the following characteristics when the emission spectrum when excited with light having a wavelength of 300 nm or more and 460 nm or less (particularly, a wavelength of 400 nm or 450 nm) is measured.
The phosphor of the present embodiment has a peak wavelength of usually 500 nm or more, preferably 510 nm or more, more preferably 520 nm or more in the above-mentioned emission spectrum. Further, it is usually 560 nm or less, preferably 550 nm or less, and more preferably 545 nm or less.
When it is within the above range, the obtained fluorescent substance exhibits a good green color, which is preferable.

[Half width of emission spectrum]
In the phosphor of the present embodiment, the half width of the emission peak in the above emission spectrum is usually 70 nm or less, preferably 60 nm or less, and usually 25 nm or more, preferably 30 nm or more.
Within the above range, it can be used in an image display device such as a liquid crystal display.
When used to widen the color reproduction range of an image display device without further reducing the color purity, the half width of the emission peak is preferably 50 nm or less, more preferably 48 nm or less, further preferably 45 nm or less, and even more preferably 43 nm or less. Is particularly preferable.

[Intensity ratio in emission spectrum]
When the phosphor of this embodiment is used in order to widen the color reproduction range without lowering the color purity in the above-mentioned image display device, in addition to the above-mentioned half-value width range, the peak ratio of the emission spectrum is as follows. It should be in the range of.
When the intensity at 512 nm in the emission spectrum is P1 and the intensity at 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, still more preferably. It is 0.7 or more, more preferably 0.9 or more, particularly preferably 1.1 or more, remarkably preferably 1.3 or more, and usually 3.0 or less, preferably 2.5 or less.

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. Further, for the measurement of the emission spectrum of the phosphor of the present embodiment and the calculation of the emission peak wavelength, peak relative intensity and peak half price width thereof, for example, a 150 W xenon lamp as an excitation light source and a multi-channel CCD detector as a spectrum measurement device are used. This can be performed using a fluorescence measuring device (manufactured by Nippon Spectroscopy) equipped with C7041 (manufactured by Hamamatsu Photonics).

[CIE chromaticity coordinates]
The x value of the CIE chromaticity coordinates of the phosphor of the present 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. Below, it is more preferably 0.380 or less, still more preferably 0.360 or less, 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, still more preferably 0.640 or more, and usually. 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 deteriorating the color purity when used in an image display device such as a liquid crystal display.

[Temperature characteristics (light emission intensity maintenance rate)]
The fluorescent material of this embodiment is also excellent in temperature characteristics. Specifically, the ratio of the emission peak intensity value in the emission spectrum diagram at 150 ° C. to the emission peak intensity value in the emission spectrum diagram at 25 ° C. when irradiated with light having a wavelength of 450 nm is usually 50%. The above is preferably 60% or more, and particularly preferably 70% or more.
Further, since the emission intensity of a normal phosphor 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%, color shift tends to occur due to a temperature change.
When measuring the above temperature characteristics, a conventional method may be followed, and examples thereof include the method described in JP-A-2008-138156.

[Excitation wavelength]
The fluorophore of the present embodiment usually has an excitation peak in a wavelength range of 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 blue region from near-ultraviolet rays.

<Manufacturing method of phosphor>
The raw materials, the fluorescent substance manufacturing method, and the like for obtaining the fluorescent substance of this embodiment are as follows.
The method for producing the phosphor of the present embodiment is not particularly limited, and is, for example, a raw material for the element M, which is an active element (hereinafter, appropriately referred to as “M source”), and a raw material for the element Al (hereinafter, appropriately referred to as “Al source”). ), The raw material of the elemental Si (hereinafter, appropriately referred to as "Si source") is mixed so as to have the chemical quantitative ratio of the formula [1] (mixing step), and the obtained mixture is calcined (firing step). Can be manufactured.
Further, in the following, for example, the raw material of the element Eu may be referred to as "Eu source".

[Fluorescent material]
The phosphor raw materials (that is, M source, Al source and Si source) used in the production of the phosphor of the present 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, halides and the like. From these compounds, it may be appropriately selected in consideration of the reactivity to the composite oxynitride, the low amount of NOx, SOx and the like generated at the time of firing, and the like.

(M source)
Among the M sources, specific examples of the Eu source include Eu ₂ O ₃ , Eu ₂ (SO ₄ ) ₃ , Eu ₂ (C ₂ O ₄ ) ₃・ 10H ₂ O, EuCl ₂ , EuCl ₃ , and Eu (NO _{3). ) 3 · 6H 2 O, EuN} , EuNH and the like. Among them, Eu ₂ O ₃ , EuN and the like are preferable, and EuN is particularly preferable.
Further, as specific examples of raw materials for other active elements such as Sm source, Tm source, and Yb source, in each compound mentioned as a specific example of Eu source, Eu is replaced with Sm, Tm, Yb, etc., respectively. Can be 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. Of these, AlN and Al ₂ O ₃ are preferable, and AlN is particularly preferable. Further, as AlN, those having a small particle size from the viewpoint of reactivity and high purity from the viewpoint of luminous efficiency are preferable.
The amount of oxygen contained in Al metal or AlN is usually 100 ppm or less, more preferably 50 ppm or less, still more preferably 20 ppm or less.
As a specific example of the raw material of the other trivalent element, in each of the compounds mentioned as a specific example of the Al source, a compound in which Al is replaced with B, Ga, In, Sc, Y, La, Gd, Lu or the like is used. Can be mentioned. As the Al source, a single Al may be used.

(Si source)
Specific examples of the Si source include SiO ₂ , α-type Si ₃ N ₄ , β-type Si ₃ N ₄ , and α-type Si ₃ N ₄ and β-type Si ₃ N ₄ are preferable. Further, _{a compound that becomes SiO 2} can also be used. Specific examples of such a compound include SiO ₂ , H ₄ SiO ₄ , Si (OCOCH ₃ ) _{4, and the} like. From the viewpoint of reactivity as α-type Si ₃ N _4, small particle size, high purity from the standpoint of emission efficiency it is preferred. Further, it is preferable that the content ratio of the carbon element which is an impurity is small.
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 of 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 heat-treat α-type Si 3} N ₄ having a high oxygen content at 1.0 MPa or less and 1600 ° C. or higher to obtain β-type Si ₃ N _{4 having a low oxygen content.}
Specific examples of raw materials for other tetravalent elements include compounds in which Si is replaced with Ge, Ti, Zr, Hf, or the like in each of the compounds mentioned as specific examples of the Si source. As the Si source, a single Si may be used.

As the above-mentioned M source, Al source and Si source, only one type may be used, or two or more types may be used in any combination and ratio.

[Mixing process]
The fluorophore raw material is weighed so that the desired composition can be obtained, sufficiently mixed using a ball mill or the like, filled in a crucible, fired at a predetermined temperature and atmosphere, and the fired product is crushed and washed. The fluorophore of the embodiment 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 and the like.
As a wet mixing method, for example, a solvent such as water or a dispersion medium is added to the above-mentioned phosphor raw material, and the mixture is mixed using a mortar and a pestle to prepare a solution or a slurry, and then spray-dried or heat-dried. 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 fluorescent material. The material of the heat-resistant container used at the time of firing is not particularly limited as long as the effect of the present embodiment is not impaired, and examples thereof include a crucible such as boron nitride.

The firing temperature varies depending on other conditions such as pressure, but usually firing can be 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 tends to fly off and cause defects in the matrix crystal to be colored, and if it is too low, the progress of the solid phase reaction tends to be slow, and it may be difficult to obtain the target phase as the main phase. ..
In order to further reduce oxygen mixed in the crystal structure, it is preferable to calcinate at a maximum 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 and the like, it is usually 0.2 MPa or more, preferably 0.4 MPa or more, and 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 maximum 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 firing at the above temperature, it is possible to obtain a crystalline phase having a low oxygen content. If the calcination 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.

Further, even if a very small amount of the desired crystal phase is obtained, the element that is the center of light emission, particularly the Eu element, may not be diffused in the crystal and the quantum efficiency may be lowered. Further, if the firing temperature is too high, the elements constituting the target phosphor crystal tend to volatilize, and there is a high possibility that lattice defects are formed or decomposed to generate another phase as an impurity.

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. Is. If the heating rate is below this range, the firing time may be long. Further, if the temperature rising rate exceeds this range, the firing device, the container, etc. may be damaged.

The firing atmosphere in the firing step is arbitrary as long as the phosphor of the present embodiment can be obtained, but a nitrogen-containing atmosphere is preferable. Specific examples thereof 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.

The firing time varies depending on the temperature and pressure at the time of firing, 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, and if the firing time is too long, volatilization of the constituent elements is promoted, resulting in atomic defects. In some cases, defects are induced in the crystal structure and a phosphor having good characteristics cannot be obtained.

The firing step may be repeated a plurality of times, if necessary. In that case, the firing conditions may be the same or different between the first firing and the second firing.

Repeated firing is effective when the atoms are uniformly diffused during the formation of the phosphor and the phosphor having high internal quantum efficiency is fired or when large particles of several μm are obtained.

Further, in the case of producing the fluorescent substance of the present embodiment, 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 during the firing step. It is preferable to use it as a (crystal growth aid).
When a phosphor is produced using a flux, constituent elements of the flux such as Li, Na, Mg, Ca, Sr, and Ba may be mixed in the phosphor.
It is preferable that the flux in this embodiment has an effect of reducing the ratio of oxygen in the obtained phosphor in addition to the effect as the above-mentioned crystal growth assisting agent. By reducing the proportion of oxygen in the phosphor in addition to the effect of growing crystals, it becomes possible to produce a phosphor having a narrow half-value width of the emission spectrum.
In addition, in order to reduce the ratio of oxygen in the obtained phosphor, Si metal, Al metal and the like may be used as the substance to be added.

Further, in order to reduce the ratio of oxygen in the crystal phase, it is preferable to use a member that adsorbs the gas for the purpose of trapping the gas containing oxygen in the constituent elements such as SiO generated at the time of firing. In particular, a member made of C (carbon) is preferable, and a felt made of C or a C cube may be arranged in the vicinity of the BN crucible.

[Post-treatment process]
The obtained fired product is crushed, crushed and / or classified into a powder having a predetermined size. Here, it is _{advisable to process so that D 50} is about 30 μm or less.
As a specific example of the treatment, a method of classifying the compound into a sieve having an opening of about 45 μm and passing the powder through the sieve to the next step, or a general method of pulverizing the compound to a ball mill, a vibration mill, a jet mill, or the like. Examples thereof include a method of crushing to a predetermined particle size using a crusher. In the latter method, excessive pulverization not only produces fine particles that easily scatter light, but also creates crystal defects on the surface of the particles, which may cause a decrease in luminous efficiency.

Further, if necessary, a step of cleaning the phosphor (fired product) may be provided. After the washing step, the phosphor is dried until the attached moisture disappears and is used. Further, if necessary, dispersion / classification treatment may be performed to loosen the agglomeration.
The phosphor of the present embodiment may be formed by a so-called alloying method in which a constituent metal element is alloyed in advance and the constituent metal element is nitrided to form the phosphor.

{Fluorescent compound-containing composition}
The fluorescent substance according to the first embodiment of the present invention can also 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 an application such as a light emitting device, it is preferable to use the phosphor in a form dispersed in a liquid medium. A liquid medium in which the fluorescent substance according to the first embodiment of the present invention is dispersed is appropriately referred to as "a fluorescent substance-containing composition according to an embodiment of the present invention" as one embodiment of the present invention. I will call it.

[Fluorescent material]
There is no limitation on the type of the fluorescent substance according to the first embodiment of the present invention contained in the fluorescent substance-containing composition of the present embodiment, and any of the above-mentioned ones can be selected. Further, the fluorescent substance according to the first embodiment of the present invention to be contained in the fluorescent substance-containing composition of the present embodiment may be only one kind, and two or more kinds may be used in combination in any combination and ratio. May be good. Further, the fluorescent substance-containing composition of the present embodiment may contain a fluorescent substance other than the fluorescent substance according to the first embodiment of the present invention as long as the effect of the present embodiment is not significantly impaired.

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

[Liquid medium and fluorophore content]
The content of the fluorescent substance and the liquid medium in the fluorescent substance-containing composition of the present embodiment is arbitrary as long as the effect of the present embodiment is not significantly impaired, but for the liquid medium, the fluorescent substance-containing composition of the present embodiment is used. It 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, based on the whole.

[Other ingredients]
The fluorescent substance-containing composition of the present embodiment may contain other components in addition to the fluorescent substance and the liquid medium as long as the effects of the present embodiment are not significantly impaired. Further, as the other components, only one kind may be used, or two or more kinds may be used in any combination and ratio.

{Light emitting device}
A second embodiment of the present invention is a light emitting device including a first light emitting body (excitation light source) and a second light emitting body that emits visible light by irradiation of light from the first light emitting body. , The second light emitter contains the phosphor according to the first embodiment of the present invention. Here, as the fluorescent substance according to the first embodiment of the present invention, any one type may be used alone, or two or more types may be used in combination in any combination and ratio.

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

As the excitation source, a source 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 an emission peak in a wavelength range of 500 nm or more and 560 nm or less, and the first emitter has an emission peak in a wavelength range of 300 nm or more and 460 nm or less. However, the present embodiment is not limited to these.

In the above case, the light emitting device of this embodiment can be, for example, the following aspect.
That is, as the first light emitter, one having an emission peak in the wavelength range of 300 nm or more and 460 nm or less is used, and as the first phosphor of the second light emitter, one having an emission peak in the wavelength range of 500 nm or more and 560 nm or less is used. A fluorescent substance having an emission peak in the wavelength range of 580 nm or more and 680 nm or less as the second fluorescent substance of the second light emitter using at least one kind of fluorescent substance (the fluorescent substance according to the first embodiment of the present invention). (Red fluorescent substance) can be used.

(Red fluorescent substance)
As the red fluorescent substance in the above embodiment, for example, the following fluorescent substance is preferably used.
Examples of the active fluoride phosphor with Mn include K ₂ (Si, Ti) F ₆ : Mn, K ₂ Si _1-x Na _x Al _x F ₆ : Mn (0 <x <1),
The sulfide phosphor, for example, (Sr, Ca) S: Eu (CAS _{phosphor), La 2 O 2 S:} Eu (LOS phosphor),
Examples of the garnet-based 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 above is 0 <x <1)
And so on.
Above all, when used as an image display device having a wide color reproduction range, the half 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, still more preferable. Is 30 nm or less, usually 5 nm or more, more preferably 10 nm or more. Among the above-mentioned phosphor, Mn-activated fluoride phosphors, SrLiAl ₃ N _4: it is preferable to use a Eu phosphor.

(Yellow phosphor)
In the above embodiment, a fluorescent substance (yellow fluorescent substance) having an emission peak in the range of 550 to 580 nm may be used, if necessary.
As the yellow fluorescent substance, for example, the following fluorescent substances are preferably used.
Examples of the garnet-based 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), and so on.
Examples of the (acid) nitride phosphor 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)
And so on.
In the above phosphor, a garnet-based phosphor is _{preferable,, Y 3 Al 5 O 12:} YAG -based phosphor represented by Ce is most preferred.

(Green fluorophore)
In the above aspect, the green fluorescent substance may contain a fluorescent substance other than the fluorescent substance according to the first embodiment of the present invention, and for example, the following fluorescent substance is preferably used.
Examples of the garnet-based 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 fluorophore),
Examples of the silicate-based phosphor include (Ba, Sr, Ca, Mg) ₃ SiO ₁₀ : (Eu, Ce), (Ba, Sr, Ca, Mg) ₂ SiO ₄ : (Ce, Eu) (BSS phosphor). ),
Examples of the oxide phosphor include (Ca, Sr, Ba, Mg) (Sc, Zn) ₂ O ₄ : (Ce, Eu) (CASO phosphor), and the like.
Examples of the (acid) nitride phosphor 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). 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-based phosphor) and the like.

[Configuration of light emitting device]
The light emitting device of the present embodiment has a first light emitting body (excitation light source), and at least the phosphor according to the first embodiment of the present invention is used as the second light emitting body. The configuration is not limited, and a known device configuration can be arbitrarily adopted.
Examples of the device configuration and the embodiment of the light emitting device include those described in JP-A-2007-291352.
In addition, as the form of the light emitting device, a cannonball type, a cup type, a chip-on-board, a remote phosphor, and the like can be mentioned.

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

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

[Image display device]
A fourth embodiment of the present invention is an image display device including a light emitting device according to a 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 the image display device, the specific configuration of the image display device is not limited, but it is preferably used together with the color filter. For example, when the image display device is a color image display device using a color liquid crystal display element, the light emitting device is used as a backlight, an optical shutter using a liquid crystal display, and a color filter having red, green, and blue pixels. An image display device can be formed by combining the above.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as it does not deviate from the gist thereof.

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

[Saturation coordinates]
The chromaticity coordinates of the x and y color systems (CIE 1931 color system) are based on the data in the wavelength region of 460 nm to 800 nm of the emission spectrum obtained by the above method, in accordance with JIS Z8724, in JIS Z8701. It was calculated as the chromaticity coordinates CIEx and CIEy in the specified XYZ color system.

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

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

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

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

{Manufacturing of fluorescent material}
[Examples 1 to 7]
As phosphor materials, _EuN, using _Si 3 N 4, AlN, was prepared following as phosphor.
The above raw materials were weighed with an electronic balance so as to have each weight shown in Table 1 below, placed in an alumina mortar, and pulverized and mixed until uniform. _{Further, 1.00 g of Mg 3} N ₂ (manufactured by Shellac) was added to this mixed powder as a flux, and further pulverization and mixing were carried out. These operations were performed in a glove box filled with Ar gas.

About 0.5 g of the obtained mixed raw material 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., Ltd.). Then, 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 heating rate of 20 ° C./min. When the temperature reached 800 ° C., the temperature was maintained and nitrogen gas was introduced for 5 minutes until the pressure in the furnace reached 0.85 MPa. After the introduction of the nitrogen gas, the pressure inside the furnace was maintained at 0.85 MPa, the temperature was further raised to 1600 ° C., and the temperature was maintained for 1 hour. Further, it was heated to 1950 ° C., and when it reached 1950 ° C., it was maintained for 4 hours. After firing, it was cooled to 1200 ° C. and then allowed to cool. Then, the product was crushed to obtain the fluorophore of Examples 3-7. For Examples 1 and 2, after crushing the product, green crystals were selected to obtain the fluorescent substances of Examples 1 and 2.

The result of SEM observation about the fluorescent substance 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 carried out to investigate the constituent elements and their ratios. The 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). The numbers in parentheses represent the 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 carried out. As a result of considering 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 and b = 7. It was indexed as .6265 (4) Å, c = 2.9075 (2) Å, α = 90 °, β = 90 °, γ = 120 °. The unit cell volume of the phosphor of Example 1 was 146.454 Å ³ .

Further, the excitation / emission spectra of the phosphor of Example 1 are shown in FIG. The excitation spectrum is a monitor of emission at 540 nm. The emission spectrum is a measurement result when excited at 450 nm. It was confirmed that 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 exhibited green emission.

For the fluorescent substances of Examples 2 and 3, single crystals of Examples 2 and 3 were selected from SEM observation, and EPMA composition analysis was performed. The 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 0. It was 006 (1): 0.030 (1): 2.97 (2). The numbers in parentheses represent the standard deviation. It was confirmed that the mixing of oxygen during firing was almost zero.

The fluorescent material 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 pattern of the phosphor of Examples 3, 4, 5, and 7 is shown in FIG. Table 2 shows the lattice constants and unit lattice volumes of the phosphors of Examples 2 to 7 refined from the obtained powder X-ray diffraction pattern. In Examples 2 to 7, a fluorescent substance having the same structure as that of Example 1 was obtained in almost a single phase.

The phosphor obtained by the first embodiment of the present invention has an a-axis from 7.604 Å to 7.6265 Å and a c-axis from 2.906 Å by changing the ratio of Eu: Al: Si in the crystal. It was found that the unit cell volume ^{changed from 145.53 Å 3} to 146.454 Å ^{3 with the change to 2.908 Å.}
The emission spectra of the phosphors of Examples 2, 3, 5, and 7 when excited by light having a wavelength of 450 nm are shown in FIG. Table 3 shows the emission peak wavelength, full width at half maximum, and 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 has an emission peak wavelength of 513 nm to 540 nm and a half width of 40 nm in the emission spectrum by changing the ratio of Eu: Al: Si in the crystal. It became clear that it was possible to change the wavelength up to 76 nm. That is, it is possible to obtain light emission from blue-green to yellow-green by using an arbitrary composition.

[Example 8]
_{Using Eu 2} O ₃ , Si ₃ N ₄ , Al N, and Al ₂ O ₃ as a raw material for the phosphor, a phosphor was prepared as follows.
As Si ₃ N ₄ , α-type Si ₃ N ₄ (manufactured by Ube Industries: 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 above raw materials were weighed with an electronic balance so as to have each weight shown in Table 4 below, placed in an alumina mortar, and pulverized and mixed until uniform in the atmosphere. Magnesium nitride was not used in Example 8.
About 2.0 g of the obtained mixed raw material 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., Ltd.). Then, 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 heating rate of 20 ° C./min. When the temperature reached 800 ° C., the temperature was maintained and nitrogen gas was introduced for 5 minutes until the pressure in the furnace reached 0.85 MPa. After the introduction of the nitrogen gas, the pressure inside the furnace was maintained at 0.85 MPa, the temperature was further raised to 1600 ° C., and the temperature was maintained for 1 hour. Further, it was heated to 2000 ° C., and when it reached 2000 ° C., it was maintained for 4 hours. After firing, it was cooled to 1200 ° C. and then allowed to cool. Then, the product was crushed to obtain the fluorophore 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 the oxygen nitrogen hydrogen analyzer were carried out. As a result, oxygen was detected, and the atomic ratio of Eu: Al: Si: О: N was 0.003: 0.05: 2.95: 0.04: 3.91.
The emission spectra of the phosphors of Examples 4 and 8 when excited by light having a wavelength of 450 nm are shown in FIG. Table 5 shows the emission peak wavelength, full width at half maximum, and chromaticity read from the emission spectrum when excited with light having a wavelength of 450 nm for the phosphors of Examples 4 and 8.
It was clarified that by reducing the oxygen in the crystal structure, the emission peak wavelength was shortened and the half width was also narrowed.

Claims (7)

A fluorescent substance 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 active element and represents an active element.
0 <m ≤ 0.04
a + b = 3
0 <a ≤ 0.08
3.6 ≤ d ≤ 4.2
x <a) A fluorescent substance 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 active element and represents an active element.
0 <m ≤ 0.04
a + b = 3
0 <a ≤ 0.08
3.6 ≤ d ≤ 4.2) M element in the formula [1] or [2] is Eu, Eu crystal having a β-type Si ₃ N ₄ crystal structure is a crystal structure of the solid solution sialon crystal, according to claim 1 or 2 Phosphorus. The fluorescence according to any one of claims 1 to 3, wherein the fluorescence peak wavelength is in the range of 500 nm or more and 560 nm or less by irradiating with excitation light having a wavelength of 300 nm or more and 460 nm or less. body. A first illuminant and a second illuminant that emits visible light by irradiation of light from the first illuminant are provided, and the second illuminant is according to any one of claims 1 to 4. A light emitting device comprising the above-mentioned fluorescent substance. A lighting device comprising the light emitting device according to claim 5 as a light source. An image display device comprising the light emitting device according to claim 5 as a light source.

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