CN109699179B

CN109699179B - Phosphor, light-emitting device, illumination device, and image display device

Info

Publication number: CN109699179B
Application number: CN201780053292.7A
Authority: CN
Inventors: 吉村文孝; 山根久典
Original assignee: Tohoku University NUC; Mitsubishi Chemical Corp
Current assignee: Tohoku University NUC; Mitsubishi Chemical Corp
Priority date: 2016-09-26
Filing date: 2017-09-25
Publication date: 2022-03-29
Anticipated expiration: 2037-09-25
Also published as: WO2018056447A1; JPWO2018056447A1; TWI808946B; CN109699179A; JP6985704B2; TW201817853A

Abstract

The present invention provides a phosphor characterized by comprising the following formula [2]]The crystalline phases shown. M_mAl_aO_xSi_bN_d[2](the above formula [2]]Wherein M represents an activating element, M is more than 0 and less than or equal to 0.04, a + b is 3, a is more than 0 and less than or equal to 0.08, d is more than or equal to 3.6 and less than or equal to 4.2, and x is less than or equal to a. ).

Description

Phosphor, light-emitting device, illumination device, and image display device

Technical Field

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

Background

In recent years, due to the trend of energy saving, there has been an increasing demand for illumination and backlight using LEDs. The LED used here is a white light-emitting LED in which a phosphor is disposed on an LED chip that emits light of blue or near ultraviolet wavelength.

As this type of white light emitting LED, in recent years, a white light emitting LED using a nitride phosphor that emits red light and a phosphor that emits green light on a blue LED chip using blue light from the blue LED chip as excitation light is used.

In particular, in the display application, the visibility of green to the human eye is particularly high among 3 colors of blue, green and red, and the luminance of the entire display is greatly contributed, so that it is particularly important to develop a green phosphor having excellent emission characteristics compared with the other 2 colors.

As a phosphor emitting green light, for example, Sr is disclosed_2.7Si₁₃Al₃O₂N₂₁: a phosphor represented by a composition formula of eu0.3 (patent document 1); from Si_6-zAl_zO_zN_8-zA phosphor represented by a composition formula of (0 < z < 4.2) (patent document 2); and containing Eu dissolved in beta-type Si₃N₄A sialon crystal phosphor having a crystal structure (patent document 3).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2012/124480

Patent document 2: japanese patent laid-open publication No. 2005-255895

Patent document 3: international publication No. 2006/101095

Disclosure of Invention

Although various phosphors have been developed as described above, phosphors having excellent emission characteristics have been desired.

In view of the above problems, the present invention provides a novel phosphor having a crystal structure different from that of conventional phosphors, having good emission characteristics, and being capable of being effectively used for LED applications.

The present inventors have intensively studied a new fluorescent material in view of the above-mentioned problems, and as a result, have found a new fluorescent material which is different from the conventional fluorescent materials and can be effectively used for LED applications, and have completed the present invention.

The present invention is as follows.

[1] A phosphor is characterized by containing a crystal phase represented by the following formula [2 ].

M_mAl_aO_xSi_bN_d [2]

(in the above formula [2], M represents an activating element, M is 0 < m.ltoreq.0.04, a + b is 3, a is 0 < a.ltoreq.0.08, d is 3.6. ltoreq.4.2, and x is a)

[2] A phosphor is characterized by containing a crystal phase represented by the following formula [1 ].

M_mAl_aSi_bN_d [1]

(in the above formula [1], M represents an activating element, 0 < m.ltoreq.0.04, a + b.ltoreq.3, 0 < a.ltoreq.0.08, 3.6. ltoreq. d.ltoreq.4.2)

[3]According to the above [1]Or [2]]The phosphor, wherein the formula [1]]Or [2]]Wherein the M element is Eu, and the phosphor is Eu solid-dissolved in beta-type Si₃N₄Crystal structure of sialon crystal.

[4] The phosphor according to any one of the above [1] to [3], characterized by having an emission peak wavelength in a range of 500nm or more and 560nm or less by irradiation with excitation light having a wavelength of 300nm or more and 460nm or less.

[5] A light-emitting device comprising a first light-emitting body and a second light-emitting body which emits visible light by being irradiated with light from the first light-emitting body, wherein the second light-emitting body contains the phosphor according to any one of the above [1] to [4 ].

[6] An illumination device, characterized by comprising the light-emitting device according to [5] above 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, and thus can be effectively used for LED applications.

Therefore, a light-emitting device using the novel phosphor of the present invention has excellent color rendering properties. Further, an illumination device and an image display device including the light-emitting device of the present invention have high quality.

Drawings

Fig. 1 is an image (photograph in place of the drawing) of the phosphor obtained in example 1, which was obtained by a scanning electron microscope.

FIG. 2 is a graph showing the excitation/emission spectrum of the phosphor obtained in example 1. The broken line indicates the excitation spectrum and the solid line indicates the emission spectrum.

FIG. 3 is a diagram showing the powder X-ray diffraction (XRD) patterns of the phosphors obtained in examples 3, 4, 5 and 7.

FIG. 4 is a graph showing the emission spectra of the phosphors obtained in examples 2, 3, 5 and 7.

FIG. 5 is a graph showing the emission spectra of the phosphors obtained in examples 4 and 8.

Detailed Description

The present invention will be described below by showing embodiments and examples, but the present invention is not limited to the embodiments, examples, and the like described below, and can be carried out by arbitrarily changing the embodiments without departing from the scope of the present invention.

In the present specification, the numerical range expressed by "to" means a range including the numerical values described before and after "to" as the lower limit value and the upper limit value. In the composition formula of the phosphor in the present specification, the division of each composition formula is represented by a dash (,). When a plurality of elements are listed with a comma (,) being separated, it means that one or two or more of the listed elements may be contained in any combination and composition. For example, "(Ca, Sr, Ba) Al₂O₄: eu "is a composition formula that generally represents all of the following: "CaAl₂O₄：Eu”、“SrAl₂O₄：Eu”、“BaAl₂O₄：Eu”、“Ca_1-xSr_xAl₂O₄：Eu”、“Sr_1-xBa_xAl₂O₄：Eu”、“Ca_1-xBa_xAl₂O₄：Eu”、“Ca_1-x-ySr_xBa_yAl₂O₄: eu' (wherein, 0 < x < <inthe formula)1，0＜y＜1，0＜x+y＜1)。

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

[ phosphor ]

The phosphor according to the first embodiment of the present invention contains a crystal phase represented by the following formula [1 ].

M_mAl_aSi_bN_d [1]

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

Further, Eu may be partially substituted with at least one element selected from Ce, Pr, Sm, Tb, and Yb, and Ce is more preferable from the viewpoint of emission quantum efficiency.

That is, M is more preferably Eu and/or Ce, and is more preferably Eu.

The ratio of Eu to the total active elements is preferably 50 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more.

Al represents aluminum. Al may be partially substituted with other chemically similar 3-valent elements such as boron (B), gallium (Ga), indium (In), scandium (Sc), yttrium (Y), lanthanum (La), gadolinium (Gd), lutetium (Lu), and the like.

Si represents silicon. Si may be partially replaced by other chemically similar 4-valent elements such as germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), hafnium (Hf), and the like.

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

Oxygen is an element that is inevitably mixed into the phosphor of the present embodiment, considering the case of mixing as an impurity in the raw metal, the case of introducing during the manufacturing process such as the pulverization step and the nitriding step, and the like.

In addition, when a halogen atom is contained, the halogen atom may be contained in the phosphor particularly when a halide is used as a flux, in consideration of mixing of impurities in the metal as a raw material, introduction of the halogen atom in a manufacturing process such as a pulverization step and a nitriding step, and the like.

M represents the content of the activating element M, and is usually 0 < m.ltoreq.0.04, with the lower limit value being preferably 0.0001, more preferably 0.0005, further preferably 0.001, further preferably 0.005, and the upper limit value being preferably 0.02, further preferably 0.01, and particularly preferably 0.005.

a represents the content of Al, and is usually 0 < a.ltoreq.0.08, with the lower limit value being preferably 0.0001, more preferably 0.001, still more preferably 0.005, and the upper limit value being preferably 0.06, more preferably 0.04.

b represents the content of Si element.

The correlation between a and b satisfies a + b of 3.

d represents the content of N, and is usually 3.6. ltoreq. d.ltoreq.4.2, the lower limit thereof is preferably 3.8, more preferably 3.9, particularly preferably 3.95, and the upper limit thereof is preferably 4.1, more preferably 4.05.

If any of the contents is within the above range, it is preferable that the phosphor obtained has good emission characteristics, particularly good emission luminance.

The phosphor of the present embodiment can maintain its crystal structure by replacing the Si-N portion in the crystal structure with Al-O even when oxygen is mixed therein. When Al is more than Si, the charge compensation relationship can be maintained and O can be placed at the N site.

On the other hand, the phosphor of the present embodiment is characterized by containing no oxygen or a very small amount of oxygen in the composition. In the present specification, the absence of oxygen in the composition is the same as or less than the detection limit of oxygen in the elemental analysis of a phosphor powder by an EPMA or oxyhydrogen analyzer described later. When the oxygen content of the phosphor of the present embodiment is less than that of Al, although it is not yet determined how to compensate the charge balance, it is considered that a part of Al and Eu are substituted in pairs or defects are introduced, and thus the balance may be locally maintained.

In this case, Al/Eu is preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.2 or more, still more preferably 0.5 or more, and particularly preferably 1.0 or more.

Another embodiment of the phosphor of the present embodiment is a phosphor characterized by containing a crystal phase represented by the following formula [2 ].

M_mAl_aO_xSi_bN_d [2]

In the formula, the values of the M element, Al, Si, N and M, a, b and d are considered to be the same as those in the formula [1 ].

x represents the content of oxygen (O), and the range is not particularly limited, but x < a is preferable. That is, the content of O is preferably less than that of Al. 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 as described above. x is preferably 0.05 or less, more preferably 0.04 or less, even more preferably 0.03 or less, even more preferably 0.01 or less, and particularly preferably O is the detection limit or less, and oxygen is not contained in the composition formula (that is, x is 0), according to elemental analysis using an EPMA or oxynitrides analyzer. Therefore, x is preferably 0 or more, and the case where x is 0 corresponds to the above formula [1 ].

x/a is preferably 1.0 or less, more preferably 0.8 or less, further preferably 0.6 or less, further preferably 0.4 or less, and particularly preferably 0.2 or less, and in particular, similarly to the above, oxygen is preferably not more than the detection limit and oxygen is not contained in the composition formula (that is, x is 0 and x/a is 0) in the elemental analysis using the EPMA and oxynitrogen analyzer.

Further, if the introduction of defects that may be generated due to the fact that the content of O is less than that of Al is excessive, the defects may become quenching sites (killers sites) and degrade the light emission characteristics. Therefore, x + d is preferably 3.6 or more, more preferably 3.7 or more, further preferably 3.8 or more, further preferably 3.9 or more, and particularly preferably 3.95 or more.

{ physical Properties of phosphor }

[ Crystal Structure ]

The crystal structure of the phosphor of the present embodiment is preferably such that Eu is solid-dissolved in Si having a beta-type₃N₄Crystal structure of sialon crystal. As Si₃N₄The crystal structure is generally known as α -type and β -type, but the phosphor of the present embodiment is preferably β -type because it provides an emission peak having a desired emission wavelength and half-peak width.

[ lattice constant ]

The lattice constant of the phosphor of the present embodiment varies depending on the kind of the element constituting the crystal, but is within the following range.

The lattice constant of the a-axis (lattice constant La) is usually

The lower limit value of (1) is preferably

More preferably

Further preferred is

In addition, the upper limit value is preferably

More preferably

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 generally

In the range ofThe limit value is preferably

More preferably

In addition, the upper limit value is preferably

More preferably

Further preferred is

In addition, if either is within the above range, the phosphor of the present embodiment is stably produced, and the production of the impurity phase is suppressed, so that the obtained phosphor has good emission luminance.

[ unit cell volume ]

The unit cell volume (V) of the phosphor of the present embodiment calculated from the lattice constant is preferably

Above, more preferably

The above is more preferable

The above, in addition, are preferably

Hereinafter, more preferred is

Hereinafter, it is more preferable that

The following.

If the unit cell volume is too large or too small, the skeleton structure is unstable and impurities having other structures are by-produced, which tends to decrease the emission intensity and the color purity.

[ space group ]

The crystal system in the phosphor of the present embodiment is a Hexagonal system (Hexagonal).

The SPACE GROUP in the phosphor of the present embodiment is not particularly limited as long as the repetition period of the above length is represented by a statistically considered average structure in a range that can be distinguished by single crystal X-ray diffraction, and is preferably 173 (P6) based on "International Tables for Crystallography (Third, reviewed edition) and Volume a SPACE-GROUP SYMMETRY" (P6)₃) Or No.176 (P6)₃/m)。

The lattice constant and the space group can be determined by a conventional method. The lattice constant can be obtained by performing Rietveld (Rietveld) analysis on the results of X-ray diffraction and neutron beam diffraction, and can be obtained by electron beam diffraction in the case of a space group.

[ luminescent colors ]

The phosphor of the present embodiment can be excited with light having a wavelength of from 300nm to 500nm in the near-ultraviolet region to the blue region by adjusting the chemical composition or the like to form desired luminescent colors such as blue, cyan, green, yellow-green, yellow, orange, red, and the like.

[ luminescence spectrum ]

The phosphor of the present embodiment preferably has the following characteristics when measured in an emission spectrum when excited with light having a wavelength of 300nm to 460nm (particularly, a wavelength of 400nm or 450 nm).

The peak wavelength in the emission spectrum of the phosphor of the present embodiment is usually 500nm or more, preferably 510nm or more, and more preferably 520nm or more. The particle size is usually 560nm or less, preferably 550nm or less, and more preferably 545nm or less.

When the amount is within the above range, the obtained phosphor exhibits a favorable green color, and therefore, the phosphor is preferable.

[ half-Width of luminescence Spectrum ]

The half-width of the emission peak in the emission spectrum of the phosphor of the present embodiment is usually 70nm or less, preferably 60nm or less, and is usually 25nm or more, preferably 30nm or more.

Within the above range, the resin composition can be used for an image display device such as a liquid crystal display.

In order to expand the color reproduction range of the image display device without lowering the color purity, the half-width of the emission peak is preferably 50nm or less, more preferably 48nm or less, still more preferably 45nm or less, and particularly preferably 43nm or less.

[ intensity ratio in luminescence spectrum ]

In the image display device described above, when the phosphor of the present embodiment is used to expand the color reproduction range without lowering the color purity, the peak ratio of the emission spectrum is preferably in the following range in addition to the above-described range of the half-value width.

When the intensity at 512nm and the intensity at 525nm in the emission spectrum are P1 and P2, respectively, 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 0.7 or more, yet more preferably 0.9 or more, particularly preferably 1.1 or more, particularly preferably 1.3 or more, and usually 3.0 or less, preferably 2.5 or less.

When the phosphor of the present embodiment is excited with light having a wavelength of 400nm, for example, a GaN-based LED can be used. Further, for example, measurement of the emission spectrum of the phosphor of the present embodiment and calculation of the emission peak wavelength, peak relative intensity and peak half width thereof can be performed using a 150W xenon lamp as an excitation light source and a fluorescence measuring apparatus (manufactured by japan spectrophotometers) equipped with a multichannel CCD detector C7041 (manufactured by Hamamatsu Photonics corporation) as a spectrum measuring apparatus.

[ CIE chromaticity coordinates ]

The phosphor of the present embodiment has a value of x in CIE chromaticity coordinate of usually 0.240 or more, preferably 0.250 or more, more preferably 0.260 or more, usually 0.420 or less, preferably 0.400 or less, more preferably 0.380 or less, further preferably 0.360 or less, and further preferably 0.340 or less. The y value of the CIE chromaticity coordinate of the phosphor of the present embodiment is usually 0.575 or more, preferably 0.580 or more, more preferably 0.620 or more, further preferably 0.640 or more, usually 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 expanded without reducing the color purity when the device is used in the image display device such as a liquid crystal display.

[ temperature characteristics (light emission intensity maintenance ratio) ]

The phosphor of the present embodiment is also excellent in temperature characteristics. Specifically, when light having a wavelength of 450nm is irradiated, the ratio of the emission peak intensity value in the emission spectrum at 150 ℃ to the emission peak intensity value in the emission spectrum at 25 ℃ is usually 50% or more, preferably 60% or more, and particularly preferably 70% or more.

In addition, since the emission intensity of a general phosphor decreases with an increase in temperature, it is difficult to consider that the ratio exceeds 100%, but may exceed 100% for some reason. However, if the amount exceeds 100%, color shift tends to occur due to temperature change.

In the measurement of the temperature characteristics, the measurement may be carried out by a conventional method, and examples thereof include the method described in japanese patent application laid-open No. 2008-138156.

[ excitation wavelength ]

The phosphor of the present embodiment has an excitation peak in a wavelength range of usually 300nm or more, preferably 320nm or more, more preferably 400nm or more, and usually 480nm or less, preferably 470nm or less, more preferably 460nm or less. That is, the excitation is performed with light in the near ultraviolet to blue region.

< method for producing phosphor >

The raw materials for obtaining the phosphor of the present embodiment, the method for producing the phosphor, and the like are as follows.

The method for producing the phosphor of the present embodiment is not particularly limited, and can be produced, for example, by the following steps: a raw material of an element M (hereinafter, appropriately referred to as an "M source"), a raw material of an element Al (hereinafter, appropriately referred to as an "Al source"), and a raw material of an element Si (hereinafter, appropriately referred to as an "Si source") are mixed so as to be in a stoichiometric ratio of the formula [1] (mixing step), and the obtained mixture is fired (firing step).

Hereinafter, for example, the raw material of element Eu may be referred to as "Eu source" or the like.

[ phosphor raw Material ]

Examples of the phosphor raw material (i.e., M source, Al source, and Si source) used for producing the phosphor of the present embodiment include metals, alloys, imide compounds, nitrogen oxides, nitrides, oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates, halides, and the like of each of the M element, Al element, and Si element. The compound may be appropriately selected from these compounds in consideration of reactivity to the complex nitrogen oxide, low generation amount of NOx, SOx, and the like at the time of firing, and the like.

(M source)

Specific examples of the Eu source among the M sources include Eu₂O₃、Eu₂(SO₄)₃、Eu₂(C₂O₄)₃·10H₂O、EuCl₂、EuCl₃、Eu(NO₃)₃·6H₂O, EuN, EuNH, etc. Among them, Eu is preferred₂O₃EuN, etc., and particularly preferred is EuN.

Specific examples of the raw materials of other activating elements such as Sm source, Tm source, Yb source, etc. include compounds obtained by replacing Eu with Sm, Tm, Yb, etc. respectively, among the compounds listed as specific examples of Eu source.

(Al source)

Specific examples of the Al source include AlN and Al₂O₃、Al(OH)₃、AlOOH、Al(NO₃)₃And the like. Of these, AlN and Al are preferable₂O₃AlN is particularly preferred. Further, AlN preferably has a small particle size from the viewpoint of reactivity, and is preferable from the viewpoint of luminous efficiencyFrom the viewpoint of (1), high purity is preferred.

The amount of oxygen contained in the Al metal or AlN is usually 100ppm or less, more preferably 50ppm or less, and still more preferably 20ppm or less.

Specific examples of the raw material of the other 3-valent element include compounds obtained by substituting Al with B, Ga, In, Sc, Y, La, Gd, Lu, and the like, among the compounds listed as specific examples of the Al source. In addition, the Al source may use simple Al.

(Si source)

Specific examples of the Si source include SiO₂Alpha type Si₃N₄Beta type Si₃N₄Preferably alpha-type Si₃N₄Beta type Si₃N₄. In addition, SiO can also be used₂The compound of (1). Specific examples of such a compound include SiO₂、H₄SiO₄、Si(OCOCH₃)₄And the like. In addition, as alpha-type Si₃N₄The particle size is preferably small in view of reactivity, and the purity is preferably high in view of luminous efficiency. Further, the content ratio of carbon as an impurity is preferably small.

In order to reduce the oxygen content in the product, it is preferable to use a Si source having a smaller oxygen content. Si metal may be used, or Si with a small oxygen content may be used₃N₄. Alpha type Si₃N₄Beta type Si₃N₄The oxygen content in (A) is usually 100ppm or less, preferably 80ppm or less, more preferably 60ppm or less, further preferably 40ppm or less, particularly preferably 20ppm or less. More preferably, the alpha-Si is more rich in oxygen under the conditions of 1.0MPa or less and 1600 ℃ or more₃N₄Heat treatment is carried out to form beta-type Si with low oxygen content₃N₄And then used.

Specific examples of the raw material of the other 4-valent element include compounds obtained by substituting Ge, Ti, Zr, Hf, etc. for Si in each of the compounds listed as the specific examples of the Si source. Further, the Si source may use elemental Si.

The M source, Al source, and Si source may be used alone or in combination of two or more kinds at any ratio.

[ mixing Process ]

The phosphor of the present embodiment can be obtained by weighing phosphor raw materials so as to obtain a target composition, sufficiently mixing the raw materials using a ball mill or the like, filling the mixture into a crucible, firing the mixture at a predetermined temperature under an atmosphere, and pulverizing and washing the fired product.

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 ball milling.

As the wet mixing method, for example, the following methods are used: a solvent or a dispersion medium such as water is added to the phosphor raw material, and the mixture is mixed with a pestle using a mortar to form a solution or a slurry, and then dried by spray drying, heat drying, natural drying, or the like.

[ firing Process ]

The obtained mixture is charged into 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 for such firing is not particularly limited as long as the effects of the present embodiment are not impaired, and examples thereof include crucibles such as boron nitride crucibles.

The firing temperature may vary depending on other conditions such as pressure, but the firing temperature may be usually 1700 ℃ or higher and 2150 ℃ or lower. The maximum temperature in the firing step is usually 1700 ℃ or higher, preferably 1750 ℃ or higher, and usually 2150 ℃ or lower, preferably 2100 ℃ or lower.

If the firing temperature is too high, nitrogen tends to scatter and defects tend to be formed in the matrix crystal, 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.

When the amount of oxygen mixed into the crystal structure is further reduced, it is preferable to carry out the firing at the maximum reaching temperature of 1800 ℃ or higher, more preferably 1900 ℃ or higher, and particularly preferably 2000 ℃ or higher.

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

When firing is performed under a pressure of 10MPa or less in the firing step, the maximum temperature at the time of firing is usually 1800 ℃ or more, preferably 1900 ℃ or more, and usually 2150 ℃ or less, more preferably 2100 ℃ or less.

By firing at the above temperature, a crystal phase with a small oxygen content can be obtained. If the firing temperature is less than 1800 ℃, the solid-phase reaction does not proceed, and therefore, there is a case where only an impurity phase or an unreacted phase appears, and it is difficult to obtain the target phase as a main phase.

Even if a very small amount of the target crystal phase is obtained, the element that becomes the emission center in the crystal, particularly Eu element, may not be diffused, and the quantum efficiency may be lowered. Further, if the firing temperature is too high, the elements constituting the target phosphor crystal are easily volatilized, and there is a high possibility that lattice defects are formed or other phases are generated as impurities by decomposition.

The temperature rise rate in the firing step is usually 2 ℃/min or more, preferably 5 ℃/min or more, more preferably 10 ℃/min or more, and usually 30 ℃/min or less, preferably 25 ℃/min or less. If the temperature increase rate is lower than this range, the firing time may become longer. If the temperature rise rate exceeds this range, the firing equipment, the container, and the like may be damaged.

The firing atmosphere in the firing step is arbitrary as long as the phosphor of the present embodiment is obtained, but a nitrogen-containing atmosphere is preferable. Specifically, a nitrogen atmosphere containing hydrogen, and the like can be mentioned, and among them, a nitrogen atmosphere is preferable. The oxygen content in the firing atmosphere is usually 10ppm or less, preferably 5ppm or less.

The firing time varies depending on the temperature, pressure, and the like at the time of firing, but is usually 10 minutes or more, preferably 30 minutes or more, and is usually 72 hours or less, preferably 12 hours or less. If the firing time is too short, the growth of crystal grains and growth of crystal grains cannot be promoted, and thus a phosphor having good characteristics cannot be obtained, and if the firing time is too long, volatilization of constituent elements is promoted, and therefore, defects are induced in the crystal structure due to atomic deficiency, and a phosphor having good characteristics cannot be obtained in some cases.

The firing step may be repeated as many times as necessary. In this case, the firing conditions may be the same in the first firing and the second firing, or may be different.

When a phosphor having high internal quantum efficiency is obtained by firing a phosphor in which atoms are uniformly diffused during the production of the phosphor, repeated firing is effective.

In addition, in the case of producing the phosphor of the present embodiment, in the above firing step, it is preferable to use, for example, Li₃N、Na₃N、Mg₃N₂、Ca₃N₂、Sr₃N₂、Ba₃N₂Etc. as a flux (crystal growth assistant).

In the case of producing a phosphor using flux, constituent elements of the flux such as Li, Na, Mg, Ca, Sr, Ba, and the like may be mixed into the phosphor.

The flux in the present embodiment preferably has an effect of reducing the proportion of oxygen in the obtained phosphor in addition to the above-described effect as a crystal growth assisting agent. In addition to the effect of growing crystals, the phosphor having a narrow half-value width of the emission spectrum can be produced by reducing the proportion of oxygen in the phosphor.

In addition, in order to reduce the proportion of oxygen in the obtained phosphor, Si metal, Al metal, or the like may be used as an additive substance.

In order to reduce the proportion of oxygen in the crystal phase, it is preferable to use a member that adsorbs oxygen contained in constituent elements such as SiO generated during firing for the purpose of trapping the gas. A member made of C (carbon) is particularly preferable, and C felt or C cube is preferably arranged in the vicinity of the BN crucible.

[ post-treatment Process ]

The resultant fired product is subjected to crushing, pulverization and/or classification to obtain a powder having a predetermined size. Here, with D₅₀The treatment is preferably carried out so as to be about 30 μm or less.

Specific examples of the treatment include a method in which the composition is subjected to a sieve classification treatment with a mesh size of about 45 μm, and the powder passing through the sieve is transferred to the next step; a method of pulverizing the composition into a predetermined particle size using a general pulverizer such as a ball mill, a vibration mill, or a jet mill. In the latter method, excessive pulverization not only generates fine particles that easily scatter light, but also may cause crystal defects on the particle surface, resulting in a decrease in light emission efficiency.

Further, a step of cleaning the phosphor (fired material) may be provided as necessary. After the washing step, the phosphor is dried until the adhered moisture disappears, and is used. Further, in order to loosen the aggregation, dispersion and classification treatment may be performed as necessary.

The phosphor of the present embodiment may be formed by a so-called alloying method in which the constituent metal elements are alloyed in advance and nitrided.

{ phosphor-containing composition }

The phosphor of the first embodiment of the present invention may also be used in a mixture with a liquid medium. In particular, when the phosphor according to the first embodiment of the present invention is used in applications such as a light-emitting device, it is preferably used in a form in which it is dispersed in a liquid medium. The composition obtained by dispersing the phosphor according to the first embodiment of the present invention in a liquid medium is appropriately referred to as "a phosphor-containing composition according to an embodiment of the present invention" or the like as an embodiment of the present invention.

[ phosphor ]

The kind of the phosphor of the first embodiment of the present invention contained in the phosphor-containing composition of the present embodiment is not limited, and can be arbitrarily selected from the above phosphors. The phosphor of the first embodiment of the present invention contained in the phosphor-containing composition of the present embodiment may be one kind, or two or more kinds may be used in combination at an arbitrary combination and ratio. In addition, the composition containing a phosphor according to 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 target range. For example, any inorganic material and/or organic material may be used as long as the phosphor of the first embodiment of the present invention exhibits a liquid state under the desired use conditions, and the phosphor is appropriately dispersed without causing an undesirable reaction, and examples thereof include a silicone resin, an epoxy resin, a polyimide silicone resin, and the like.

[ content of liquid Medium and phosphor ]

The content ratio of the phosphor and the liquid medium in the phosphor-containing composition of the present embodiment is arbitrary as long as the effects of the present embodiment are not significantly impaired, and the liquid medium is usually 50% by weight or more, preferably 75% by weight or more, usually 99% by weight or less, and preferably 95% by weight or less, relative to the entire phosphor-containing composition of the present embodiment.

[ other ingredients ]

In addition, the composition containing a phosphor according to the present embodiment may contain other components in addition to the phosphor and the liquid medium, as long as the effects of the present embodiment are not significantly impaired. In addition, only one kind of the other component may be used, or two or more kinds may be used in combination in an arbitrary 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-emitting body containing the phosphor of the first embodiment of the present invention. Here, the phosphor according to the first embodiment of the present invention may be used alone, or two or more kinds may be used in combination and ratio as desired.

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

Further, as the excitation source, an excitation source having a light emission peak in a wavelength range of less than 420nm may also be used.

Hereinafter, a description will be given of a light-emitting device in which the phosphor of the first embodiment of the present invention has an emission peak in a wavelength range of 500nm to 560nm inclusive and the first light-emitting body has an emission peak in a wavelength range of 300nm to 460nm inclusive is used, but the present invention is not limited to these.

In the above case, the light-emitting device of the present embodiment can be, for example, the following.

That is, the following manner is possible: a phosphor having an emission peak in a wavelength range of 300nm or more and 460nm or less is used as the first phosphor, at least one phosphor having an emission peak in a wavelength range of 500nm or more and 560nm or less (the phosphor of the first embodiment of the present invention) is used as the first phosphor of the second light-emitting body, and a phosphor having an emission peak in a wavelength range of 580nm or more and 680nm or less (the red phosphor) is used as the second phosphor of the second light-emitting body.

(Red phosphor)

As the red phosphor in the above embodiment, for example, the following phosphor is preferably used.

Examples of the Mn-activated fluoride phosphor include K₂(Si，Ti)F₆：Mn、K₂Si_1-xNa_xAl_xF₆：Mn(0＜x＜1)；

Examples of the sulfide phosphor include (Sr, Ca) S: eu (CAS fluorophor), La₂O₂S: eu (LOS phosphor);

examples of the garnet-based phosphor include (Y, Lu, Gd, Tb)₃Mg₂AlSi₂O₁₂：Ce；

Examples of the nanoparticles include CdSe;

examples of the nitride or oxynitride phosphor include: (Sr, Ca) AlSiN₃: eu (S/CASN phosphor) and (CaAlSiN)₃)_1-x·(SiO₂N₂)_x: eu (CASON fluorophor), (La, Ca)₃(Al，Si)₆N₁₁: eu (LSN phosphor), (Ca, Sr, Ba)₂Si₅(N，O)₈: eu (258) phosphor, and (Sr, Ca) Al_1+xSi_4-xO_xN_7-x: eu (1147 phosphor), M_x(Si，Al)₁₂(O, N) 16: eu (M is Ca, Sr, etc.) (alpha-sialon phosphor), Li (Sr, Ba) Al₃N₄: eu (x is more than 0 and less than 1).

In particular, when the red phosphor of the above embodiment is used as an image display device having a wide color reproduction range, the half-peak width of the emission spectrum of the red phosphor is usually 90nm or less, preferably 70nm or less, more preferably 50nm or less, further preferably 30nm or less, and usually 5nm or more, more preferably 10nm or more. Among the above phosphors, Mn-activated fluoride phosphor and SrLiAl are preferably used₃N₄: a Eu phosphor.

(yellow phosphor)

In the above embodiment, a phosphor (yellow phosphor) having a light emission peak in a range of 550 to 580nm may be used as necessary.

As the yellow phosphor, for example, the following phosphors are preferably used.

Examples of the garnet-based phosphor include (Y, Gd, Lu, Tb, La)₃(Al，Ga)₅O₁₂：(Ce，Eu，Nd)；

Examples of the orthosilicate include (Ba, Sr, Ca, Mg)₂SiO₄：(Eu，Ce)；

Examples of the (oxy) nitride phosphor include (Ba, Ca, Mg) Si₂O₂N₂: eu (SION-based phosphor), (Li, Ca)₂(Si，Al)₁₂(O，N)₁₆: (Ce, Eu) (alpha-sialon phosphor), (Ca, Sr) AlSi₄(O，N)₇: (Ce, Eu) (1147 phosphor), (La, Ca, Y)₃(Al，Si)₆N₁₁: ce (LSN phosphor), and the like.

Among the above phosphors, garnet phosphors are preferable, and among them, Y is most preferable₃Al₅O₁₂: a YAG phosphor represented by Ce.

(Green phosphor)

In the above embodiment, the green phosphor may contain a phosphor other than the phosphor according to the first embodiment of the present invention, and for example, the following phosphor is preferably used.

Examples of the garnet-based phosphor include (Y, Gd, Lu, Tb, La)₃(Al，Ga)₅O₁₂：(Ce，Eu，Nd)、Ca₃(Sc，Mg)₂Si₃O₁₂: (Ce, Eu) (CSMS phosphor);

examples of the silicate-based phosphor include (Ba, Sr, Ca, Mg)₃SiO₁₀：(Eu，Ce)、(Ba，Sr，Ca，Mg)₂SiO₄: (Ce, Eu) (BSS phosphor);

examples of the oxide phosphor include (Ca, Sr, Ba, Mg) (Sc, Zn)₂O₄: (Ce, Eu) (CASO phosphor);

examples of the (oxy) nitride phosphor include (Ba, Sr, Ca, Mg) Si₂O₂N₂：(Eu，Ce)、Si_6- _zAl_zO_zN_8-z: (Eu, Ce) (beta-sialon phosphor) (z 0 < 1), (Ba, Sr, Ca, Mg, La)₃(Si，Al)₆O₁₂N₂: (Eu, Ce) (BSON phosphor);

examples of the aluminate phosphor include (Ba, Sr, Ca, Mg)₂Al₁₀O₁₇: (Eu, Mn) (GBAM based phosphor), and the like.

[ constitution 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 of the first embodiment of the present invention is used as the second light emitting body.

An example of an embodiment of the device configuration and the light-emitting device is disclosed in japanese patent application laid-open No. 2007-291352.

In addition, the form of the light-emitting device includes a shell type, a cup type, a chip on board, a remote phosphor (remote phosphor), and the like.

{ use of light-emitting device }

The light-emitting device according to the second embodiment of the present invention can be used in various fields where a light-emitting device is generally used, but is particularly suitable as a light source for an illumination device or an image display device, in view of a wide color reproduction range and high color rendering properties.

[ Lighting device ]

A third embodiment of the present invention is a lighting 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 described above may be used by being appropriately incorporated into a known lighting device. For example, a surface-emitting illumination device in which a plurality of light-emitting devices are arranged on the bottom surface of a holding case is given.

[ image display apparatus ]

A fourth embodiment of the present invention is an image display device including the light-emitting device according to the second embodiment of the present invention as a light source.

In the case where the light-emitting device of 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 together with a color filter. For example, when a color image display device using color liquid crystal display elements is used as the image display device, the image display device can be formed by using the light emitting device as a backlight and combining a shutter using liquid crystal with color filters having red, green, and blue pixels.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the invention does not depart from the gist thereof.

< method of measurement >

[ luminescence characteristics ]

The sample was loaded on a copper sample holder, and the excitation luminescence spectrum and the luminescence spectrum were measured using a fluorescence spectrophotometer FP-6500 (manufactured by JASCO corporation). In the measurement, the slit width of the light receiving side spectrometer was set to 1 nm. Further, the emission peak wavelength (hereinafter, sometimes referred to as "peak wavelength") and the half-peak width of the emission peak are read from the obtained emission spectrum.

[ chromaticity coordinates ]

From the data of the wavelength region of 460nm to 800nm of the emission spectrum obtained by the above-mentioned method, the chromaticity coordinates of the x and y color system (CIE1931 color system) were calculated as the chromaticity coordinates CIEx and CIEy in the XYZ color system prescribed in JIS Z8701 by the method in accordance with JIS Z8724.

[ elemental analysis Using 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 several crystals were selected by observation with a Scanning Electron Microscope (SEM), each element was analyzed with an electron probe microanalyzer (wavelength dispersive X-ray analysis apparatus: EPMA) JXA-8200 (manufactured by JEOL). The detection limit of oxygen in this apparatus was 100 ppm.

[ elemental analysis by ICP ]

The quantitative analysis of Si, Al, Eu and Mg may be replaced by the following ICP elemental analysis, in addition to the EPMA elemental analysis.

After melting a sample with an alkali, an acid was added to dissolve the sample, and the obtained sample solution was diluted as appropriate and quantified with an inductively coupled plasma emission spectrometer iCAP7600Duo (manufactured by Thermo Fisher Scientific). The measurement conditions were as follows.

RF power: 1200W

Atomizer gas flow: 0.60L/min

Flow rate of cooling gas: 12L/min

Auxiliary gas: 1.0L/min

[ O, N quantitation ]

Quantitative analysis was carried out by a pulse oven heating extraction-NIR (O) detection method/TCD (N) detection method in an inert gas atmosphere in an oxy-nitrogen-hydrogen analyzer (TCH 600 manufactured by LECO Co.). In addition, the limit of detection of oxygen of the present apparatus was 0.2 wt%, and about 0.1g of the sample was measured in examples and comparative examples.

[ powder X-ray diffraction measurement ]

Powder X-ray diffraction the powder X-ray diffraction was precisely measured by a powder X-ray diffraction apparatus D2PHASER (manufactured by BRUKER). The measurement conditions were as follows.

Using CuK alpha bulb

X-ray output of 30KV and 10mA

Scanning range 2 theta is 5-65 deg

Read width of 0.025 °

[ refinement of lattice constant ]

From the powder X-ray diffraction measurement data of each example, a peak derived from a crystal structure classified into (P63/m) (intrinsic Tables for Crystallography, No.176) in the space group was extracted, and the peak was refined using TOPAS 4 software for data processing (Bruker corporation), thereby obtaining a lattice constant.

{ production of phosphor }

[ examples 1 to 7]

Using EuN, Si₃N₄AlN was used as a phosphor raw material, and a phosphor was prepared as follows.

The raw materials were weighed by an electronic balance so as to be each weight shown in table 1 below, put into an alumina mortar, and pulverized and mixed until uniform. Further, 1.00g of Mg was added to the mixed powder₃N₂(manufactured by SHELLAC corporation) was further pulverized and mixed as a flux. These operations were performed in a glove box filled with Ar gas.

[ Table 1]

TABLE 1

About 0.5g of the raw material mixed powder was weighed out and directly charged in a boron nitride crucible. The crucible was placed in a vacuum pressure firing furnace (Shimadzu Mectem Co., Ltd.). Then, the pressure was reduced to 8X 10^-3After Pa or less, the mixture was vacuum-heated from room temperature to 800 ℃ at a temperature-raising rate of 20 ℃/min. After reaching 800 ℃, nitrogen gas was maintained and introduced at the temperature for 5 minutes until the furnace pressure became 0.85 MPa. After introducing nitrogen gas, the temperature was further raised to 1600 ℃ while keeping the furnace pressure at 0.85MPa, and the temperature was maintained for 1 hour. Further heating to 1950 deg.C, and maintaining for 4 hr after 1950 deg.C is reached. After firing, the resultant was cooled to 1200 ℃ and then cooled. Then, the resultant was crushed to obtain phosphors of examples 3 to 7. In addition, in examples 1 to 2, the product was crushed, and green crystals were selected, thereby obtaining the phosphors of examples 1 to 2.

The results of SEM observation of the phosphor of example 1 are shown in fig. 1. The single crystal of example 1 was selected by SEM observation, and elemental analysis (EPMA measurement) was performed to examine the constituent elements and their proportions. The elements detected in EPMA are Eu, Al, Si, N, and magnesium and oxygen are below the detection limit. Results of quantitative analysis, Eu: al: atomic ratio of Si 0.016 (1): 0.048(1): 2.95(2). The numbers in parentheses indicate standard deviations. It was confirmed that the oxygen mixed during firing was substantially zero.

Next, the single crystal structure analysis of example 1 was performed. As a result of taking into consideration the fundamental reflection obtained by single crystal X-ray diffraction, the phosphor of example 1 had a hexagonal crystal system in crystal system and an index of lattice constant of hexagonal system

α is 90 °, β is 90 °, and γ is 120 °. In addition, the phosphor of example 1 had a cell volume of

Fig. 2 shows the excitation and emission spectra of the phosphor of example 1. Excitation spectroscopy monitored 540nm luminescence. The emission spectrum is a measurement result when the sample is excited at 450 nm. It was confirmed that the phosphor of example 1 exhibited an emission spectrum having an emission peak wavelength of 540nm and a half-width of 70nm, and exhibited green emission.

The phosphors of examples 2 and 3 were analyzed for EPMA composition by selecting single crystals of examples 2 and 3 through SEM observation. The elements detected in EPMA were Eu, Al, Si, and N in the same manner as in example 1, and magnesium and oxygen were not more than the detection limit. In addition, as a result of the quantitative analysis, Eu: al: the atomic ratio of Si was 0.008(1) in example 2: 0.039(1): 2.96(2), 0.006(1) in example 3: 0.030(1): 2.97(2). The numbers in parentheses indicate standard deviations. It was confirmed that the oxygen mixed during firing was substantially zero.

The phosphor of example 4 was subjected to composition analysis by ICP and O/N analysis by an oxynitridic hydrogen analyzer. As a result, oxygen was below the detection limit, Eu: al: the atomic ratio of Si is 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. 3. Table 2 shows the lattice constants and the unit cell volumes of the phosphors of examples 2 to 7, which were refined from the obtained powder X-ray diffraction pattern. In examples 2 to 7, phosphors having the same structure as in example 1 were obtained substantially in a single phase.

[ Table 2]

TABLE 2

It is understood that the phosphor obtained by the first embodiment of the present invention has a high luminous efficiency by changing the Eu: al: ratio of Si, a-axis from

Change to

c axis from

Change to

At the same time, the unit cell volume is also increased

Change to

FIG. 4 shows emission spectra of the phosphors of examples 2, 3, 5 and 7 when excited by light having a wavelength of 450 nm. In addition, the emission peak wavelength, half-width and chromaticity read from the emission spectrum when the phosphor of examples 2 to 7 was excited with light having a wavelength of 450nm are shown in Table 3.

[ Table 3]

TABLE 3

It is clarified that the phosphor obtained by the first embodiment of the present invention is obtained by changing the Eu: al: the ratio of Si enables the emission peak wavelength in the emission spectrum to be changed from 513nm to 540nm and the half-width to be changed from 40nm to 76 nm. That is, by using an arbitrary composition, light emission from cyan to yellow can be obtained.

[ example 8]

Using Eu₂O₃、Si₃N₄、AlN、Al₂O₃As a phosphor raw material, a phosphor was prepared as follows.

As Si₃N₄For alpha-type Si, a nitrogen atmosphere at a pressure of 0.92MPa is used₃N₄(manufactured by UK Kagaku K.K.: SN-E10) was subjected to heat treatment at 1950 ℃ for 12 hours to obtain a mixtureSi of beta type₃N₄。

The raw materials were weighed with an electronic balance so as to be each weight shown in table 4 below, put into an alumina mortar, and pulverized and mixed in the air until uniform. In example 8, magnesium nitride was not used.

About 2.0g of the raw material mixed powder was weighed out and directly charged in a boron nitride crucible. The crucible was placed in a vacuum pressure firing furnace (Shimadzu Mectem Co., Ltd.). Then, the pressure was reduced to 8X 10^-3After Pa or less, the mixture was vacuum-heated from room temperature to 800 ℃ at a temperature-raising rate of 20 ℃/min. After reaching 800 ℃, nitrogen gas was maintained and introduced at the temperature for 5 minutes until the furnace pressure became 0.85 MPa. After introducing nitrogen gas, the temperature was further raised to 1600 ℃ while keeping the furnace pressure at 0.85MPa, and the temperature was maintained for 1 hour. Further heating was carried out to 2000 ℃ and the temperature was maintained at 2000 ℃ for 4 hours. After firing, the resultant was cooled to 1200 ℃ and then cooled. Then, the resultant was crushed to obtain a phosphor of example 8.

Example 8 was a single phase of β -SiAlON.

[ Table 4]

TABLE 4

Composition analysis by ICP and O/N analysis by an oxygen nitrogen hydrogen analyzer were carried out for example 8. As a result, oxygen was detected, and Eu: al: si: and (2) O: the atomic ratio of N is 0.003: 0.05: 2.95: 0.04: 3.91.

FIG. 5 shows emission spectra of the phosphors of examples 4 and 8 when excited by light having a wavelength of 450 nm. In addition, the emission peak wavelength, half-peak width and chromaticity read from the emission spectrum when the phosphor of example 4 and example 8 was excited with light having a wavelength of 450nm are shown in table 5.

It was found that the emission peak wavelength was shortened and the half-value width was narrowed by reducing oxygen in the crystal structure.

[ Table 5]

TABLE 5

Claims

1. A phosphor comprising a crystal phase represented by the following formula [2],

M_mAl_aO_xSi_bN_d [2]

in the formula [2], M represents an activating element, M is more than 0 and less than or equal to 0.04, a + b is 3, a is more than 0 and less than or equal to 0.08, d is more than or equal to 3.6 and less than or equal to 4.2, and x/a is less than or equal to 0.4.

2. A phosphor comprising a crystal phase represented by the following formula [1],

M_mAl_aSi_bN_d [1]

in the formula [1], M represents an activating element, M is 0 < m.ltoreq.0.04, a + b is 3, a is 0 < a.ltoreq.0.08, and d is 3.6. ltoreq.4.2.

3. The phosphor according to claim 1 or 2, wherein the formula [1]]Or [2]]Wherein the M element is Eu, and the phosphor is Eu solid-dissolved in beta-type Si₃N₄Crystal structure of sialon crystal.

4. The phosphor according to claim 1 or 2, which has an emission peak wavelength in a range of 500nm or more and 560nm or less by irradiation with excitation light having a wavelength of 300nm or more and 460nm or less.

5. The phosphor according to claim 3, wherein the phosphor has an emission peak wavelength in a range of 500nm to 560nm by irradiation with excitation light having a wavelength of 300nm to 460 nm.

6. A light-emitting device comprising a first light-emitting element and a second light-emitting element which emits visible light by being irradiated with light from the first light-emitting element, wherein the second light-emitting element comprises the phosphor according to any one of claims 1 to 5.

7. An illumination device comprising the light-emitting device according to claim 6 as a light source.

8. An image display device comprising the light-emitting device according to claim 6 as a light source.