JP2016191011A - Phosphor, light emitting device, lighting device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel blue to bluish green phosphor that is useful for white light emitting LED applications.SOLUTION: Provided is a phosphor including a crystalline phase that has a composition represented by the following formula [1], and which is characterized in that the space group of the phosphor is Pnnm. MSrAlSiNO[1]. (In the above formula [1], M represents an activating element, and m, a, b, c, d and e are each independently a value satisfying the following formula: 0<m≤0.2, m+a=1, 0≤b≤0.5, 5.5≤c≤6.6, 7.5≤d≤8.8, 0≤e≤0.5.).SELECTED DRAWING: Figure 1

Description

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

In recent years, various light emitting diodes and laser diodes have been developed as semiconductor light emitting devices (LEDs). In particular, LED chips using nitride semiconductors have been developed as LED chips that can emit light efficiently on the short wavelength side from the ultraviolet region to the visible light region.
On the LED chip, a phosphor that absorbs a part of the primary light from the LED chip and emits light is disposed, and an LED that emits various emission colors including white has been developed.

A typical example of the white LED is an LED in which a blue light emitting LED chip and a yellow phosphor (for example, yttrium, aluminum, garnet phosphor: YAG phosphor) are combined. However, since the LED emits white light with two colors of blue light emission and yellow light emission, the light emission is bluish light, the color rendering property is not sufficient, and further improvement has been demanded.
In order to improve the color rendering, it is conceivable to obtain white light closer to natural light by mixing the three primary colors of light, blue, green, and red. As this configuration, for example, a combination of an LED chip that emits primary light from the ultraviolet region to the visible light region and a phosphor that emits red, blue, and green light when excited by the primary light can be given.

Among LED chips, chips having an emission peak from 380 nm to 430 nm have been developed in recent years. Therefore, a white LED in which this LED chip is combined with red, blue and green phosphors has been developed.
Various blue to blue-green phosphors used in this white LED have been developed. For example, in Patent Document 1, Eu ²⁺ activated barium magnesium aluminate phosphor or Eu ²⁺ activated alkaline earth chlorophosphate is used. It is disclosed to use a phosphor based on phosphor.
In Non-Patent Document 1, a nitride phosphor represented by a composition formula of SrSi ₆ N ₈ : Eu ²⁺ has been developed.

JP 2013-12711 A

Journal of Materials Science 2008, 43, 5659-5661

As described above, various blue to blue-green phosphors have been developed, and further, blue to blue-green phosphors having improved emission characteristics are desired.
In view of the above problems, the present invention provides a novel blue to blue-green phosphor useful for white light emitting LED applications.
In addition, the present invention provides a light-emitting device including a novel blue to blue-green phosphor, and an illumination device and an image display device including the light-emitting device.

In light of the above-mentioned problems, the present inventors diligently studied new phosphors. As a result, new blue to blue-green phosphors having a crystal structure different from conventional phosphors and effectively used for LED applications. The present invention has been completed.
The present invention is as follows.
<1>
A phosphor including a crystal phase having a composition represented by the following formula [1], wherein a space group of the phosphor is Pnnm.
_{M m Sr a Al b Si c} N d O e [1]
(In the above formula [1],
M represents an activation element,
m, a, b, c, d, and e are values that satisfy the following formulas independently.
0 <m ≦ 0.2
m + a = 1
0 ≦ b ≦ 0.5
5.5 ≦ c ≦ 6.6
7.5 ≦ d ≦ 8.8
0 ≦ e ≦ 0.5)
<2>
<1> The phosphor according to <1>, wherein the phosphor has an emission peak wavelength in a range of 430 nm to 480 nm by irradiating excitation light having a wavelength of 300 nm to 420 nm.
<3>
A first illuminant, and a second illuminant that emits visible light when irradiated with light from the first illuminant, wherein the second illuminant is the fluorescence according to <1> or <2>. A light-emitting device comprising a body.
<4>
An illumination device comprising the light-emitting device according to <3> as a light source.
<5>
An image display device comprising the light-emitting device according to <3> as a light source.

The blue to blue-green phosphor of the present invention has a crystal structure different from that of conventional phosphors, and is useful for white light emitting LED applications.
In addition, the light-emitting device including the novel blue to blue-green phosphor of the present invention, and the illumination device and the image display device including the light-emitting device are of high quality.

It is an image by the scanning electron microscope of the fluorescent substance obtained in Example 1 (drawing substitute photograph). It is a figure which shows the powder X-ray-diffraction (XRD) pattern of the fluorescent substance obtained in Example 1, and the powder X-ray-diffraction (XRD) pattern obtained by simulation. FIG. 3 is a diagram showing excitation / emission spectra of the phosphor obtained in Example 1.

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

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

<About phosphor>
[Regarding Formula [1]]
The phosphor according to the first embodiment of the present invention is a phosphor including a crystal phase having a composition represented by the following formula [1], and the space group of the phosphor is Pnnm.
_{M m Sr a Al b Si c} N d O e [1]
(In the above formula [1],
M represents an activation element,
m, a, b, c, d, and e are values that satisfy the following formulas independently.
0 <m ≦ 0.2
m + a = 1
0 ≦ b ≦ 0.5
5.5 ≦ c ≦ 6.6
7.5 ≦ d ≦ 8.8
0 ≦ e ≦ 0.5)

  In the formula [1], the activation element M is 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), or one or more elements selected from the group consisting of ytterbium (Yb). M preferably contains at least Eu, and more preferably Eu.

Further, all or part of Eu may be substituted with at least one element selected from the group consisting of Ce, Pr, Sm, Tb, and Yb, and Ce is more preferable in terms of emission quantum efficiency.
That is, M is more preferably Eu and / or Ce, and more preferably Eu.
The ratio of Eu with respect to the entire activation element is preferably 50 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more.

  In the formula [1], Sr represents strontium. Sr may be partially substituted with other divalent elements such as magnesium (Mg), calcium (Ca), barium (Ba), and zinc (Zn). In this case, Mg or Ca is preferable.

  In formula [1], Al represents aluminum. Al is another 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.

  In formula [1], Si represents silicon. Si may be partially substituted with other tetravalent elements such as germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), hafnium (Hf), and the like.

  In formula [1], N represents a nitrogen element. N only needs to contain a nitrogen element as a main component, and may contain a halogen element (fluorine (F), chlorine (Cl)) or the like within a range not affecting the characteristics of the obtained phosphor.

  In formula [1], O represents an oxygen element. O may contain other elements, such as halogen elements, within a range that does not affect the properties of the obtained phosphor.

  When a halogen element is included, it may be mixed as an impurity in the raw material metal or introduced during a manufacturing process such as a pulverization process or a nitriding process. Especially, when a halide is used as a flux, May be included.

  m represents the content of the activator element M, the range is usually 0 <m ≦ 0.2, the lower limit is preferably 0.001, more preferably 0.01, and the upper limit is , Preferably 0.15, more preferably 0.1, particularly preferably 0.08.

a represents the content of Sr.
The relationship between m and a is usually
m + a = 1
Satisfied.

  b represents the content of Al, the range is usually 0 ≦ b ≦ 0.5, and the lower limit is preferably 0.05, more preferably 0.1, still more preferably 0.2, The upper limit is preferably 0.4, and more preferably 0.3.

  c represents the content of Si, the range is usually 5.5 ≦ b ≦ 6.6, the lower limit is preferably 5.6, more preferably 5.7, and the upper limit is preferably Is 6.3, more preferably 6, even more preferably 5.8.

  d represents the content of N, the range is usually 7.5 ≦ c ≦ 8.8, the lower limit is preferably 7.7, and the upper limit is preferably 8.4, more preferably Is 8.

e represents the content of O, and the range thereof is usually 0 ≦ e ≦ 0.5, and the lower limit is preferably greater than 0, more preferably 0.05, still more preferably 0.1, particularly Preferably it is 0.2, and the upper limit is preferably 0.4, more preferably 0.3.
Any content is in the above-described range, which is preferable in terms of good emission characteristics of the obtained phosphor, particularly emission luminance.

<Physical properties of phosphor>
[Luminescent color]
The emission color of the phosphor of this embodiment is excited by light in the near ultraviolet region to blue region having a wavelength of 300 nm to 420 nm by adjusting the chemical composition and the like, and is blue, blue-green, green, yellow-green, yellow, orange , Red, etc., and a desired emission color can be obtained.

[Emission spectrum]
The phosphor of this embodiment preferably has the following characteristics when an emission spectrum is measured when excited with light of 300 nm or more and 420 nm or less.
The phosphor of this embodiment has a peak wavelength in the above-described emission spectrum of usually 430 nm or more, preferably 440 nm or more. Moreover, it is 480 nm or less normally, Preferably it is 470 nm or less.
It is preferable for the phosphor to be in the above-mentioned range since the obtained phosphor exhibits a good blue to blue-green color.

[Half width of emission spectrum]
In the phosphor of this embodiment, the half-value width of the emission peak in the above-described emission spectrum is preferably 50 nm or less, more preferably 45 nm or less, still more preferably 40 nm or less, and usually 20 nm or more.
By setting it within the above range, when used in an image display device such as a liquid crystal display, the color reproduction range of the image display device can be widened without reducing the color purity.

  In order to excite the phosphor of this embodiment with light having a wavelength of 300 nm or more and 420 nm or less, for example, a GaN-based LED can be used. In addition, the measurement of the emission spectrum of the phosphor of this embodiment and the calculation of the emission peak wavelength, peak relative intensity and peak half width are, for example, a 150 W xenon lamp as an excitation light source and a multichannel CCD detector as a spectrum measurement device. It can be performed using a fluorescence measuring apparatus (manufactured by JASCO Corporation) equipped with C7041 (manufactured by Hamamatsu Photonics).

[Excitation wavelength]
The phosphor of this embodiment usually has an excitation peak in a wavelength range of 300 nm or more, preferably 330 nm or more, more preferably 360 nm or more, and usually 420 nm or less, preferably 400 nm or less. That is, it is excited by light in the near ultraviolet to blue region.

[Crystal system and space group]
The crystal system in the phosphor of the present embodiment is orthorhombic.
In addition, the space group in the phosphor of the present embodiment is not particularly limited as long as the average structure indicates a repetition period of the above length, but “International Tables for
No. 58 (Pnnm) based on Crystallography (Third, revised edition), Volume A SPACE-GROUP SYMMETRY.
Here, the lattice constant and the space group can be obtained according to a conventional method. If it is a lattice constant, the results of X-ray diffraction and neutron diffraction can be obtained by Rietveld analysis, and if it is a space group, it can be obtained by electron beam diffraction.

[Lattice constant]
The lattice constant of the phosphor of this embodiment is as follows.
The a-axis is usually 4.59 mm or more, preferably 4.68 mm or more, more preferably 4.78 mm or more, and usually 5.07 mm or less, preferably 4.97 mm or less, more preferably 4.88 mm or less.
The b-axis is usually 8.84 mm or more, preferably 9.02 mm or more, more preferably 9.21 mm or more, and usually 9.77 mm or less, preferably 9.58 mm or less, more preferably 9.40 mm or less. .
The c-axis is usually 7.48 mm or more, preferably 7.64 mm or more, more preferably 7.80 mm or more, and usually 8.27 mm or less, preferably 8.11 mm or less, more preferably 7.96 mm or less.

[Unit cell volume]
In the phosphor of the present embodiment, the unit cell volume calculated from the lattice constant (V) is preferably 325.49A ³ or more, more preferably 339.64A ³ or more, more preferably 350.26A ³ or more, further, preferably 382.10A ³ or less, more preferably 367.95A ³ or less, further preferably 357.33A ³ or less.
Within the above range, it is preferable in that the skeleton structure is stabilized and an impurity phase having a different structure is not easily generated, and the emission luminance of the obtained phosphor is good.

<Method for producing phosphor>
The raw materials, the phosphor production method, and the like for obtaining the phosphor of this embodiment are as follows.
The method for producing the phosphor of the present embodiment is not particularly limited. For example, the raw material of the element M as an activator (hereinafter referred to as “M source” as appropriate) and the raw material of the element Sr (hereinafter referred to as “Sr source” as appropriate). ) And a raw material of elemental Al (hereinafter referred to as “Al source” as appropriate) and a raw material of elemental Si (hereinafter referred to as “Si source” as appropriate) (mixing step), and the resulting mixture is fired (firing). Step).
The raw materials are blended so as to have a composition represented by the formula [1].
Hereinafter, for example, the raw material of the element Eu may be referred to as “Eu source”, and the raw material of the element Sm may be referred to as “Sm source”.

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

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

(Sr source)
Specific examples of the Sr source include SrO, Sr (OH) ₂ .8H ₂ O, SrCO ₃ , Sr (NO ₃ ) ₂ , SrSO ₄ , Sr (C ₂ O ₄ ) · H ₂ O, Sr (OCOCH ₃ ). _{2 · 0.5H 2 O, SrCl 2} , Sr 3 N 2, SrNH and the like. Among these, SrO, SrCO ₃ , Sr ₂ N, and Sr ₃ N ₂ are preferable, and Sr ₂ N and Sr ₃ N ₂ are particularly preferable. Further, those having a small particle size from the viewpoint of reactivity and high purity from the viewpoint of light emission efficiency are preferable.
Specific examples of other divalent element materials include compounds in which Sr is replaced with Mg, Ca, Ba, Zn, or the like in each of the compounds listed as specific examples of the Sr source.

(Al source)
Specific examples of the Al source include AlN, Al ₂ O ₃ , Al (OH) ₃ , AlOOH, Al (NO ₃ ) _{3 and the} like. Among these, AlN and Al ₂ O ₃ are preferable, and AlN is particularly preferable. Moreover, as AlN, the thing with a small particle size from a reactive point and a high purity from the point of luminous efficiency is preferable.
Specific examples of other trivalent element materials include compounds in which Al is replaced with B, Ga, In, Sc, Y, La, Gd, Lu, etc. in each of the compounds listed as specific examples of the Al source. Can be mentioned.

(Si source)
As a specific example of the Si source, it is preferable to use SiO ₂ or Si ₃ N ₄ . It is also possible to use a compound as a SiO _2. Specific examples of such a compound include SiO ₂ , H ₄ SiO ₄ , Si (OCOCH ₃ ) _{4 and the} like. Further, Si ₃ N ₄ is preferably one having a small particle diameter and high purity in terms of light emission efficiency from the viewpoint of reactivity. Furthermore, the thing with few content rates of the carbon element which is an impurity is preferable.
Specific examples of other raw materials for tetravalent elements include compounds in which Si is replaced by Ge, Ti, Zr, Hf, etc. in the respective compounds listed as specific examples of the Si source.

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

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

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

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

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

  The pressure during the firing step varies depending on the firing temperature and the like, but is usually 0.2 MPa or more, preferably 0.4 MPa or more, and is usually 200 MPa or less, preferably 190 MPa or less.

The firing time varies depending on the firing temperature, pressure, etc., but is usually 10 minutes or longer, preferably 30 minutes or longer, and usually 72 hours or shorter, preferably 12 hours or shorter.
Within the above range, grain formation and grain growth can be favorably promoted, volatilization of constituent elements is suppressed, and defects are induced in the crystal structure due to atomic deficiency, resulting in good characteristics. It is preferable in that a certain phosphor is easily obtained.
In addition, you may repeat a baking process in multiple times as needed. In that case, the firing conditions may be the same or different between the first firing and the second firing.

In the case of producing the phosphor of the present embodiment, during the sintering step, for _example, it is preferable to use _{Mg 3 N 2, Li 3 N} , Na 3 N and the like as flux (crystal growth supplements).

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

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

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

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

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

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

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

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

  As the phosphor according to the first embodiment of the present invention, for example, a phosphor that emits fluorescence in a blue to blue-green region under light irradiation from an excitation light source is used. Specifically, when constituting a light emitting device, the blue or blue-green phosphor in the first embodiment of the present invention preferably has a light emission peak in a wavelength range of 430 nm or more and 480 nm or less.

In this case, the light emitting device according to the second embodiment of the present invention can be, for example, the following aspect (a) or (b).
(A) A semiconductor light emitting device having an emission peak in a wavelength range of 300 nm or more and 420 nm or less is used as the first light emitter, and the first phosphor of the second light emitter is used in the first embodiment of the present invention. An embodiment in which such a phosphor is used and a second phosphor having a light emission peak in a wavelength region of 550 nm or more and 600 nm or less (yellow phosphor) is used as the second phosphor of the second light emitter.
(B) A semiconductor light emitting device having a light emission peak in a wavelength range of 300 nm or more and 420 nm or less is used as the first light emitter, and the first phosphor of the second light emitter is used in the first embodiment of the present invention. Using such a phosphor, a second phosphor having a light emission peak in a wavelength region greater than 500 nm and less than 550 nm (green phosphor) is used as the second phosphor of the second light emitter. The aspect using the thing (red fluorescent substance) which has a light emission peak in a wavelength range larger than 600 nm and 700 nm or less as a 3rd fluorescent substance.

(Yellow phosphor)
As yellow fluorescent substance in said aspect, the following fluorescent substance is used suitably, for example.
Examples of the garnet phosphor include (Y, Gd, Lu, Tb, La) ₃ (Al, Ga) ₅ O ₁₂ : (Ce, Eu, Nd),
Examples of the orthosilicate include (Ba, Sr, Ca, Mg) ₂ SiO ₄ : (Eu, Ce),
Examples of (acid) nitride phosphors include (Ba, Ca, Mg) Si ₂ O ₂ N ₂ : Eu (SION phosphor), (Li, Ca) ₂ (Si, Al) ₁₂ (O, N ₁₆ : (Ce, Eu) (α-sialon phosphor), (Ca, Sr) AlSi ₄ (O, N) ₇ : (Ce, Eu) (1147 phosphor)
Etc.
The phosphor is preferably a garnet phosphor, and most preferably a YAG phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce.

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

(Red phosphor)
As a red fluorescent substance in said aspect, the following fluorescent substance is used suitably, for example.
Examples of the Mn-activated fluoride phosphor include K ₂ (Si, Ti) F ₆ : Mn, K ₂ Si _1-x Na _x Al _x F ₆ : Mn (0 <x <1),
Examples of sulfide phosphors include (Sr, Ca) S: Eu (CAS phosphor), La ₂ O ₂ S: Eu (LOS phosphor),
Examples of the garnet phosphor include (Y, Lu, Gd, Tb) ₃ Mg ₂ AlSi ₂ O ₁₂ : Ce,
Examples of nanoparticles include CdSe,
Examples of the nitride or oxynitride phosphor include (Sr, Ca) AlSiN ₃ : Eu (S / CASN phosphor), (CaAlSiN ₃ ) _1-x · (SiO ₂ N ₂ ) _x : Eu (CASON fluorescence). Body), (La, Ca) ₃ (Al, Si) ₆ N ₁₁ : Eu (LSN phosphor), (Ca, Sr, Ba) ₂ Si ₅ (N, O) ₈ : Eu (258 phosphor), ( _{Sr, Ca) Al 1 + x} Si 4-x O x N 7-x: Eu (1147 _{phosphors), M x (Si, Al} ) 12 (O, N) 16: Eu (M is, Ca, Sr, etc.) ( α sialon phosphor), Li (Sr, Ba) Al ₃ N ₄ : Eu (where x is 0 <x <1)
Etc.

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

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

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

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

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

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

[Elemental analysis]
In order to examine the composition of the phosphor obtained in the first embodiment of the present invention, the following elemental analysis was performed. Energy dispersive X-ray spectroscopy was used to analyze the constituent metal elements (Sr, Al, Si, Eu). Specifically, several plate-like crystals were selected by SEM observation, and each metal element was analyzed using an energy dispersive X-ray analyzer EMAX ENERGY (EMAX x-act detector specification) manufactured by Horiba.

[Powder X-ray diffraction measurement]
Powder X-ray diffraction was precisely measured with a powder X-ray diffractometer D2 PHASER (manufactured by BRUKER). The measurement conditions are as follows.
Using CuKα tube X-ray output = 30 KV, 10 mA
Scanning range 2θ = 5 ° -80 °
Reading width = 0.025 °

[Crystal structure analysis]
X-ray diffraction data of single crystal particles was measured with a single crystal X-ray diffractometer (Rigaku, R-AXIS RAPID-II) equipped with an imaging plate and a graphite monochromator and using Mo Kα as an X-ray source. RAPID-AUTO was used to collect data and refine the lattice constant, and NUMABS was used to correct X-ray shape absorption. The crystal structure parameters were refined for the F ² data using SHELXL-97. In addition, VESTA was used for drawing the crystal structure.

[Lattice constant refinement]
For the lattice constant, a peak due to the crystal structure of Example 1 is extracted from the powder X-ray diffraction measurement data of each example, and the lattice constant obtained by single crystal structure analysis is used as an initial value for data processing software (TOPAS4). It was obtained by refining using.

[Example 1]
Using Sr ₃ N ₂ (manufactured by Shellac), EuN (manufactured by Shellac), Si ₃ N ₄ (manufactured by Ube Industries), and AlN (manufactured by Tokuyama) as phosphor raw materials, phosphors are prepared as follows. did.

The raw materials were weighed with an electronic balance so as to have each weight (g) shown in Table 1, placed in an alumina mortar, and ground and mixed until uniform. Further, 0.14 g of Mg ₃ N ₂ (manufactured by Shellac Co.) was added to this mixed powder, and further pulverized and mixed. These operations were performed in a glove box filled with Ar gas.

About 0.5 g of the obtained raw material mixed powder was weighed and filled into a boron nitride crucible as it was. This crucible was placed in a vacuum pressure firing furnace (manufactured by Shimadzu Mectem Co.). Next, the pressure was reduced to 8 × 10 ⁻³ Pa or less, and then vacuum heating was performed from room temperature to 800 ° C. When the temperature reached 800 ° C., high-purity nitrogen gas (99.9995%) was introduced for 5 minutes until the pressure inside the furnace reached 0.85 MPa. After the introduction of the high purity nitrogen gas, the temperature inside the furnace was kept at 0.85 MPa, and the temperature was further raised to 1600 ° C. and kept for 1 hour. Furthermore, it heated to 2080 degreeC, and when it reached 2080 degreeC, it hold | maintained for 4 hours. After firing, it was cooled to 1200 ° C. and then allowed to cool. Blue crystals were extracted from the obtained product to obtain the phosphor of Example 1.
The results of observation with a scanning electron microscope of the phosphor of Example 1 are shown in FIG. It was confirmed that all the crystals were as shown in FIG.

Further, the result of powder X-ray diffraction measurement (XRD) of the phosphor of Example 1 is shown in FIG. It was confirmed that the XRD pattern of the phosphor of Example 1 was not a PDF but a novel phosphor.
Table 2 shows the results of elemental analysis (EPMA measurement) of this crystal.

As shown in Table 2, no elemental magnesium was detected. Therefore, the mixing of magnesium element into the crystal phase is considered to be substantially zero.
Based on the above results, the composition formula of the phosphor of Example 1 was changed to Sr _0.99 Eu _0.01 Si _5.73 Al _0.27 N _7.73 O _0.27 , and the single crystal structure analysis was performed. Then, the lattice constant, the space group, and the coordinates of each atom (Table 3) were determined as follows.

<Crystal structure analysis>
As a result of considering the basic reflection obtained by the single crystal X-ray diffraction of Example 1, a simple lattice (P lattice, lattice constant a = 4.8270 (4) Å, b = 9.3039 (8) Å, c = 7.879 (6) Å, α = 90.000 °, β = 90.000 °, γ = 90.000 °). The numbers in parentheses after the above lattice constants represent standard deviations.

Moreover, as a result of examining the reflection point of the obtained basic reflection based on the extinction rule, the space group in which the crystal structure model could be obtained using the present crystal was Pnnm. The crystal system in the phosphor of Example 1 was orthorhombic.
As for Si and Al and N and O, the Si / Al site is assumed to be 0.955 / 0.045, and the N / O site is 0.966 / 0.034 based on the result of composition analysis. And this atomic coordinates. Eu is assumed to partially substitute the Sr site in the crystal structure.
Furthermore, an X-ray diffraction pattern was simulated based on the coordinates obtained by structural analysis. The powder X-ray diffraction (XRD) pattern obtained by the simulation is shown in FIG. In view of the composition ratio calculated from the composition analysis result and the electron density, the chemical composition of the phosphor according to the first embodiment of the present invention is changed to Sr _0.99 Eu _0.01 Si _5.73 Al _0.27 N _{7. .73} O _0.27 .

The lattice constant obtained by structural analysis of the phosphor single crystal of Example 1 is set as an initial value, and FIG.
Table 4 shows the results obtained by refining the lattice constant of the phosphor of Example 1 powdered from the XRD pattern. A value almost coincident with the lattice constant obtained by single crystal X-ray diffraction was obtained, and it was confirmed that there was little variation for each crystal. The number in parentheses after the lattice constant represents the standard deviation.

The excitation / emission spectrum of the phosphor of Example 1 is shown in FIG. The excitation spectrum monitors the emission at 450 nm, and the emission spectrum is a measurement result when excited at 400 nm.
The phosphor of Example 1 emitted blue-green light, and showed an emission spectrum having an emission peak wavelength of 450 nm and a half width of 33 nm.
The half width of 33 nm in the phosphor of Example 1 is smaller than the half width of 44 nm in the phosphor described in Non-Patent Document 1. Therefore, the light emitting device including the phosphor according to the first embodiment of the present invention has higher color rendering properties and higher quality.
Furthermore, the excitation spectrum in the phosphor of Example 1 has a wide wavelength range from 280 nm to 430 nm. Therefore, excitation by various excitation sources is possible, which is preferable in terms of wide application.

Claims (5)

A phosphor including a crystal phase having a composition represented by the following formula [1], wherein a space group of the phosphor is Pnnm.
_{M m Sr a Al b Si c} N d O e [1]
(In the above formula [1],
M represents an activation element,
m, a, b, c, d, and e are values that satisfy the following formulas independently.
0 <m ≦ 0.2
m + a = 1
0 ≦ b ≦ 0.5
5.5 ≦ c ≦ 6.6
7.5 ≦ d ≦ 8.8
0 ≦ e ≦ 0.5)   The phosphor according to claim 1, wherein the phosphor has an emission peak wavelength in a range of 430 nm to 480 nm by irradiating excitation light having a wavelength of 300 nm to 420 nm.   A first illuminant and a second illuminant that emits visible light when irradiated with light from the first illuminant, wherein the second illuminant comprises the phosphor according to claim 1 or 2. A light-emitting device comprising:   An illumination device comprising the light-emitting device according to claim 3 as a light source.   An image display device comprising the light-emitting device according to claim 3 as a light source.

Images