WO2019021756A1

WO2019021756A1 - Phosphor and production method therefor, phosphor sheet, and illumination device

Info

Publication number: WO2019021756A1
Application number: PCT/JP2018/025116
Authority: WO
Inventors: 和弘八木橋
Original assignee: デクセリアルズ株式会社
Priority date: 2017-07-26
Filing date: 2018-07-02
Publication date: 2019-01-31
Also published as: JP2019026673A; JP6871098B2; TW201910490A

Abstract

Provided is a phosphor which is represented by general formula (1) and which contains at least a fluorescent substance that satisfies conditions (1)-(3). General formula (1): (BaySr1-y)1-xGa2S4:Eux (in general formula (1), 0.025≤x≤0.20 and 0.15≤y≤0.49 are satisfied). Condition (1): The maximum peak of the diffraction intensity in an XRD pattern is a diffraction peak that appears at a diffraction angle 2θ=23.7° to 24.1° and is attributed to the (422) plane of SrGa2S4. Condition (2): The second highest peak of the diffraction intensity appears at a diffraction angle 2θ=38.1° to 38.5° and is attributed to the (444) plane of SrGa2S4. Condition (3): Diffraction peaks having a relative intensity of 5-20% of the maximum peak of the diffraction intensity appear at a diffraction angle 2θ=30.0° to 30.4°.

Description

Phosphor, method for manufacturing the same, phosphor sheet, and lighting device

The present invention relates to a phosphor, a method of manufacturing the same, a phosphor sheet, and a lighting device.

Conventionally, pseudo white LEDs using a yellow phosphor YAG: Ce have been used in low-priced TVs and displays. In this method, the color purity of green and red is reduced because it does not match the characteristics of the red and green color filters.

On the other hand, in recent years, a wide color gamut is required for liquid crystal TVs and displays. However, in the above method, the color gamut is narrowed because the color purity of green and red is reduced. In order to expand the color gamut (widening of the color gamut), a three-wavelength white LED using a green light emitting phosphor and a red light emitting phosphor matching the transmission characteristics of the color filter instead of the yellow phosphor is advantageous. is there.

As a green light emitting phosphor, SrGa ₂ S ₄ : Eu phosphor is known. Since SrGa ₂ S ₄ : Eu phosphors are excited by light in the near ultraviolet to blue region, they are attracting attention as green light emitting phosphors for exciting blue LEDs.
SrGa ₂ S _4: in connection with Eu phosphor, for example, SrGa the purpose of improving internal quantum efficiency ₂ S _4: Eu phosphor, or _MGa 2 _S 4: Eu phosphor (M = Ba, Sr and / or Ca) has been proposed (see, for example, Patent Documents 1 and 2).

In order to realize a three-wavelength white LED with a wide color gamut, a green light emitting phosphor having high color purity is required while having high luminance, and thus green color having high color purity while having high luminance. There is a need for light emitting phosphors.

Patent No. 4343267 Patent No. 4708507

An object of the present invention is to solve the above-mentioned problems in the prior art and to achieve the following objects. That is, the present invention provides a green light emitting phosphor having high color purity while having high luminance, a method for producing the same, a phosphor sheet having the phosphor, and a lighting device having the phosphor sheet. With the goal.

The means for solving the problems are as follows. That is,
<1> A phosphor comprising at least a phosphor represented by the following general formula (1) and satisfying the following conditions (1) to (3).
(Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ : Eu _x ... general formula (1)
However, in the general formula (1), 0.025 ≦ x ≦ 0.20 and 0.15 ≦ y ≦ 0.49.
Condition (1): The diffraction intensity maximum peak of the XRD pattern is a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ appearing at the diffraction angle 2θ = 23.7 to 24.1 °.
Condition (2): The second peak of the diffraction intensity is a diffraction peak belonging to the (444) plane of SrGa ₂ S ₄ which appears at the diffraction angle 2θ = 38.1 to 38.5 °.
Condition (3): A diffraction peak having a relative intensity of 5 to 20% relative to the diffraction intensity maximum peak is present at a diffraction angle 2θ of 30.0 to 30.4 °.
<2> The phosphor according to <1>, wherein y value of the fluorescent substance based on CIE 1931 color system is 0.687 or more.
<3> The phosphor according to any one of <1> to <2>, wherein the internal quantum efficiency of the phosphor is 0.64 or more.
<4> A phosphor sheet comprising a phosphor layer containing the phosphor according to any one of <1> to <3> and a red phosphor.
<5> A lighting device comprising the phosphor sheet according to <4>.
<6> A method for producing a phosphor, wherein the phosphor according to any one of <1> to <3> is produced,
A barium sulfide, a strontium compound, and a europium compound are dissolved, and a first liquid containing a powdered gallium compound is mixed with a second liquid containing sulfite to form barium sulfite, strontium sulfite, and europium sulfite. It is a method for producing a phosphor, including a precipitation and precipitation step of obtaining a precipitate which is a mixture of the contained precipitate and the powdered gallium compound.
<7> The method for producing a phosphor according to <6>, further including a firing step of firing the precipitate in an atmosphere containing hydrogen sulfide.

According to the present invention, the above problems in the prior art can be solved, the above object can be achieved, and a phosphor emitting green light with high color purity while having high luminance, a method for producing the same, and the phosphor And a lighting device having the phosphor sheet.

FIG. 1 is a schematic cross-sectional view showing a configuration example of a phosphor sheet end. FIG. 2 is a schematic cross-sectional view showing an edge light type illumination device. FIG. 3 is a schematic cross-sectional view showing a direct type illumination device. FIG. 4 is a graph showing the relationship between the emission peak wavelengths of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4 and the emission peak intensity. FIG. 5 is a graph showing CIEx, y of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4. FIG. 6 is an X-ray diffraction pattern of the phosphors of Examples 1, 4, 5, 7 and Comparative Examples 1 to 4.

(Phosphor)
The phosphor of the present invention contains at least a fluorescent substance, and further contains other components such as a coating layer, if necessary.

<Fluorescent substance>
The fluorescent material is represented by the following general formula (1).
(Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ : Eu _x ... general formula (1)
However, in the general formula (1), 0.025 ≦ x ≦ 0.20 and 0.15 ≦ y ≦ 0.49.

The fluorescent material satisfies the following conditions (1) to (3).
Condition (1): The diffraction intensity maximum peak of the XRD pattern is a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ appearing at the diffraction angle 2θ = 23.7 to 24.1 °.
Condition (2): The second peak of the diffraction intensity is a diffraction peak belonging to the (444) plane of SrGa ₂ S ₄ which appears at the diffraction angle 2θ = 38.1 to 38.5 °.
Condition (3): A diffraction peak having a relative intensity of 5 to 20% relative to the diffraction intensity maximum peak is present at a diffraction angle 2θ of 30.0 to 30.4 °.

In the phosphor, the Ga / (Eu + Ba + Sr) ratio (element ratio) is preferably 1.80 to 2.50, and more preferably 1.90 to 2.30.

Examples of the emission peak wavelength of the fluorescent substance include 529 nm to 535 nm.

Examples of the emission peak intensity (ratio to YAG) of the fluorescent substance include, for example, 2.46 to 3.64.

The sample absorption rate of the fluorescent substance may be, for example, 64% to 82%.

As x based on the CIE 1931 color system of the fluorescent substance, 0.271 or less is preferable.
Examples of the x value based on the CIE 1931 color system of the fluorescent substance include 0.210 to 0.271, and 0.235 to 0.271.

The y value of the fluorescent substance based on the CIE 1931 color system is preferably 0.687 or more.
Examples of the y value based on the CIE 1931 color system of the fluorescent substance include, for example, 0.687 to 0.710, and also, 0.687 to 0.695.

The internal quantum efficiency of the fluorescent substance is preferably 0.64 (64%) or more.
The internal quantum efficiency of the fluorescent substance may be, for example, 0.64 (64%) to 0.80 (80%).

The external quantum efficiency of the fluorescent substance is preferably 0.40 (40%) or more.
Examples of the external quantum efficiency of the fluorescent substance include 0.40 (40%) to 0.65 (65%).

Examples of the luminance (ratio to YAG) of the fluorescent substance include 124% to 187%.

The full width at half maximum of the fluorescent material may be, for example, 48 nm to 50 nm.

Each of the above characteristics can be measured, for example, by the following method.

[Measurement of luminescence (PL) spectrum]
The emission peak wavelength, emission peak intensity, and emission half width in the PL spectrum are measured using an integrating sphere option of a spectrofluorimeter FP-6500 (manufactured by JASCO Corporation). The emission peak intensity is shown as a relative value based on PL spectrum data of a general YAG phosphor P46-Y3 material manufactured by Kasei Optronics.

[Calculation of various conversion efficiencies]
As the conversion efficiency of the phosphor, the efficiency of absorbing excitation light (absorptivity), the efficiency of converting absorbed excitation light into fluorescence (internal quantum efficiency), and the efficiency of converting excitation light as a product thereof into fluorescence (external Calculate quantum efficiency). The luminescence characteristics are measured using an integrating sphere option of a spectrofluorimeter FP-6500 (manufactured by JASCO Corporation). The phosphor powder is filled in a dedicated cell, and blue excitation light with a wavelength of 450 nm is irradiated to measure the fluorescence spectrum. The quantum efficiency is calculated using the result from the quantum efficiency calculation software attached to the spectrofluorimeter.

[Evaluation of crystallinity]
The crystallinity is evaluated by X-ray diffraction measurement. The position (2θ) and half width of the diffraction peak in the X-ray diffraction (XRD) pattern of the CuKα ray are measured using a powder X-ray diffractometer (X'Pert PRO manufactured by PANalytical). Perform fitting with the peak search function of the attached analysis software, and analyze the characteristics of the XRD pattern of the phosphor.

<Covering layer>
As a further preferable aspect of the fluorescent substance of this invention, the fluorescent substance by which the surface of the said fluorescent substance was coat | covered with the fluorine resin as a coating layer is mentioned.
By improving the moisture resistance and the water resistance of the fluorescent material, it is possible to prevent the hydrolysis reaction by water and the like and to prevent the deterioration of the light emission characteristics.
In order to improve the moisture resistance and water resistance of the fluorescent substance, it is preferable to coat the surface of the fluorescent substance with a fluorine-based resin. By doing so, deterioration of the fluorescent substance due to hydrolysis and the like can be prevented, and deterioration of light emission characteristics such as light emission peak intensity can be suppressed.

Physical property values such as emission peak wavelength, full width at half maximum, emission peak intensity, internal quantum efficiency, external quantum efficiency and the like differ depending on the composition of the fluorescent substance and the crystal structure.
However, when the phosphor of the present invention is produced by the production method of the present invention described later, it has a novel crystal structure and becomes a green-emitting phosphor having high color purity while having high luminance.

(Method of manufacturing phosphor)
The method for producing a phosphor of the present invention at least includes a precipitation and precipitation step, and further, if necessary, other steps such as a firing step and a coating step.
The method of producing the phosphor is a method of producing the phosphor of the present invention.

<Precipitation precipitation process>
There is no particular limitation on the precipitation precipitation step, as long as it is a step of mixing a first liquid and a second liquid to obtain a precipitate, and can be appropriately selected according to the purpose.

<< First liquid >>
The first liquid dissolves a barium compound, a strontium compound, and a europium compound, and contains a powdered gallium compound.

Examples of a method of obtaining the first liquid include a method of dissolving a barium compound, a strontium compound, and a europium compound in water and mixing powder of a gallium compound therein.

Examples of the barium compound include barium nitrate [Ba (NO ₃ ) ₂ ], barium oxide [BaO], barium bromide [BaBr ₂ .xH ₂ O], barium chloride [BaCl ₂ .xH ₂ O], and barium acetate. [Ba (CH ₃ COO) ₂ ], barium iodide [BaI ₂ .xH ₂ O], barium hydroxide [Ba (OH) ₂ ], barium sulfide [BaS] or the like can be used.

Examples of the strontium compound include strontium nitrate [Sr (NO ₃ ) ₂ ], strontium oxide [SrO], strontium bromide [SrBr ₂ .xH ₂ O], strontium chloride [SrCl ₂ .xH ₂ O], strontium carbonate [SrCO ₃ ], Strontium borate [SrC ₂ O ₄ · H ₂ O], Strontium fluoride [SrF ₂ ], Strontium iodide [SrI ₂ · xH ₂ O], Strontium sulfate [SrSO ₄ ], Strontium hydroxide [Sr (OH) ₂ · x H ₂ O], strontium sulfide [SrS] or the like can be used.

As the europium compound, for example, europium nitrate _{_{[Eu (NO 3) 3 ·}} xH 2 O], oxalate europium _{_{_{_{[Eu 2 (C 2 O 4}}}} ) 3 · xH 2 O], europium carbonate _[Eu 2 _(CO 3) ₃ · x H ₂ O], europium sulfate [Eu ₂ (SO ₄ ) ₃ ], europium chloride [EuCl ₃ · x H ₂ O], europium fluoride [EuF ₃ ], europium hydride [EuH _x ], europium sulfide [EuS ], tri -i- propoxy europium _{_{[Eu (O-i-C}} 3 H 7) 3], europium acetate _{[Eu (O-CO-CH} 3) 3] , or the like can be used.

Examples of the powdery gallium compound include gallium oxide [Ga ₂ O ₃ ], gallium sulfate [Ga ₂ (SO ₄ ) ₃ .xH ₂ O], gallium nitrate [Ga (NO ₃ ) ₃ .xH ₂ O], and odor Gallium fluoride [GaBr ₃ ], gallium chloride [GaCl ₃ ], gallium iodide [GaI ₃ ], gallium sulfide (II) [GaS], gallium sulfide (III) [Ga ₂ S ₃ ], gallium oxyhydroxide [GaOOH] Etc. can be used.

There is no restriction | limiting in particular as content of Ba, Sr, Eu, and Ga in the said 1st liquid, According to the objective, it can select suitably.

<< Second liquid >>
The second liquid contains sulfite.
As a method of obtaining the said 2nd liquid, the method of dissolving a sulfite in water is mentioned, for example.
There is no restriction | limiting in particular as content of the sulfite in the said 2nd liquid, According to the objective, it can select suitably.

As said sulfite, ammonium sulfite, sodium sulfite, potassium sulfite etc. are mentioned, for example.

There is no restriction | limiting in particular as a mixing ratio of the said 1st liquid and the said 2nd liquid, According to the objective, it can select suitably, For example, Eu, Ba, and Sr in the said 1st liquid The mixing may be performed such that the molar amount of sulfite is 1.00 times to 1.50 times the total molar amount.

<< Precipitation >>
The precipitate is a mixture of the precipitate and the powdered gallium compound.
The precipitate contains barium sulfite, strontium sulfite and europium sulfite.
In the first liquid, the barium compound, the strontium compound, and the europium compound are dissolved and uniform, so that barium sulfite, strontium sulfite, and europium sulfite are uniformly mixed even in the precipitate. .
Furthermore, in the precipitate, the powdered gallium compound, barium sulfite, strontium sulfite and europium sulfite are uniformly mixed.

In addition, it is preferable to wash | clean the said precipitate, before using for the baking process mentioned later. There is no restriction | limiting in particular as conditions for washing | cleaning, According to the objective, it can select suitably, For example, washing | cleaning with water is mentioned until it becomes 0.1 mS / cm or less in conductivity.

<Firing process>
If it is a process which bakes the said precipitate under the atmosphere containing hydrogen sulfide as said baking process, there is no restriction | limiting in particular, According to the objective, it can select suitably.
As a firing temperature in the firing step, for example, 900 ° C. to 950 ° C. may be mentioned.
The firing time in the firing step may be, for example, 1 hour to 5 hours.
There is no restriction | limiting in particular as a ratio of hydrogen sulfide in the atmosphere in the said baking process, According to the objective, it can select suitably, For example, the amount of 0.1 L / min-0.5 L / min of hydrogen sulfide is baked It is possible to supply in the atmosphere.

The fluorescent substance in the phosphor of the present invention can be obtained by the firing step.

<Coating process>
The covering step is not particularly limited as long as it is a step of covering the surface of the fluorescent material obtained by the firing step with a covering layer, and can be appropriately selected according to the purpose.
The coating step can be performed, for example, by coating a fluorine-based resin in a non-water-based atmosphere.

For example, using a fluorine-based resin solution containing a fluorine-based resin in a solvent containing fluorine such as hydrofluoroethers such as ethoxy nonafluorobutane, the fluorescent material obtained above is mixed with the fluorine-based resin solution, Mix with a mix rotor etc. Next, the powder is collected by suction filtration, and the powder is dried at a temperature of about 80 ° C. to 100 ° C. for 0.5 hour to 1.5 hours. Thereby, the fluorescent substance which has the coating layer by a fluorine resin on the surface can be obtained.

(Phosphor sheet)
The phosphor sheet of the present invention has at least a phosphor layer, and optionally, other members such as a water vapor barrier film.

<Phosphor layer>
The phosphor layer contains at least the phosphor of the present invention and a red phosphor, and further contains other components such as a resin as required.
The phosphor layer is formed, for example, by dispersing the phosphor of the present invention and the red phosphor in the layered resin.

<< Red Phosphor >>
There is no restriction | limiting in particular as said red fluorescent substance, According to the objective, it can select suitably, For example, it is from sulfide type fluorescent substance, oxide type fluorescent substance, nitride type fluorescent substance, fluoride type fluorescent substance, etc. Depending on the type of phosphor, absorption band, light emission band, etc., one or more kinds can be used in combination.

Specific examples of the red phosphor include (ME: Eu) S, (M: Sm) _x (Si, Al) ₁₂ (O, N) ₁₆ , ME ₂ Si ₅ N ₈ : Eu, (ME: Eu) SiN ₂ , (ME: Eu) AlSiN ₃ , (ME: Eu) ₃ SiO ₅ , (Ca: Eu) SiN ₂ , (Ca: Eu) AlSiN ₃ , Y ₂ O ₃ : Eu, YVO ₄ : Eu, Y ( P, V) O ₄ : Eu, 3.5 MgO · 0.5 MgF ₂ · Ge ₂ : Mn, CaSiO ₃ : Pb, Mn, Mg _{6 As} O ₁₁ : Mn, (Sr, Mg) ₃ (PO ₄ ) ₃ : Sn And La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, and the like. Among these red phosphors, CaS: Eu or (Ba, Sr) ₃ SiO ₅ : Eu capable of realizing a wide color gamut is preferably used. Here, "ME" means at least one type of atom selected from the group consisting of Ca, Sr and Ba, and "M" is at least one type selected from the group consisting of Li, Mg and Ca It means an atom. Moreover, the front of ":" shows a mother body, and after ":" shows an activator.

<< Resin >>
As said resin, the polyolefin copolymer, the hardened | cured material of photocurable (meth) acrylic resin, etc. are mentioned, for example.

As said polyolefin copolymer, a styrene-type copolymer or its hydrogenated substance can be mentioned. As such a styrene-based copolymer or a hydrogenated product thereof, a styrene-ethylene-butylene-styrene block copolymer or a hydrogenated product thereof, a styrene-ethylene-propylene block copolymer or a hydrogenated product thereof is preferably mentioned. be able to. Among these, hydrogenated products of styrene-ethylene-butylene-styrene block copolymer can be particularly preferably used from the viewpoint of transparency and gas barrier properties. By containing such a polyolefin copolymer, excellent light resistance and low water absorption can be obtained.

Examples of the photocurable (meth) acrylic resin include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate and the like, and among these, the heat resistance after photocuring From these, urethane (meth) acrylate can be preferably used. By containing such a photocurable (meth) acrylic resin, excellent light resistance and low water absorption can be obtained.

<Steam vapor barrier film>
Examples of the water vapor barrier film include a gas barrier film in which a metal oxide thin film such as aluminum oxide, magnesium oxide or silicon oxide is formed on the surface of a plastic substrate such as PET (polyethylene terephthalate) or a film. Moreover, you may use the thing of multilayer structures, such as PET / SiOx / PET.

Here, an example of the phosphor sheet will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a configuration example of a phosphor sheet end. In the phosphor sheet, the phosphor layer 11 is sandwiched between the first water vapor barrier film 12 and the second water vapor barrier film 13.

The phosphor layer 11 contains the above-mentioned phosphor of the present invention which emits green fluorescence and a red phosphor which emits red fluorescence of a wavelength of 620 to 660 nm by irradiation of blue excitation light, and the irradiated blue light is converted to white light. Convert.

In addition, as phosphors for emitting green light other than the phosphors of the present invention, Zn ₂ SiO ₄ : Mn, Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Y, Gd) Al ₃ (BO ₃ ) ₄ : Tb ^{3 +} , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, CaSc ₂ O ₄ : Ce, Ba ₃ Si ₆ O ₁₂ N ₂ : Eu, β-Sialon: Eu ²⁺ etc. from 1 type or 2 or more types in combination It is also good.

The phosphor layer 11 is formed by depositing a resin composition containing the powder-like phosphor of the present invention and a red phosphor.

Further, in the phosphor sheet of FIG. 1, the cover member 14 has an end portion of the first water vapor barrier film 12 and an end portion of the second water vapor barrier film 13 having a water vapor transmission rate of 1 g / m ² / day or less. Is preferably sealed.

As the cover member 14, it is possible to use a pressure-sensitive adhesive tape in which a pressure-sensitive adhesive 142 is applied to a substrate 141 having a water vapor transmission rate of 1 g / m ² / day or less. As the base material 141, metal foil such as aluminum foil or the like and the water

vapor barrier films

12, 13 can be used. Although aluminum foil may use either glossy white aluminum or non-lustrous black aluminum, it is preferable to use white aluminum when a good color tone at the end of the phosphor sheet is required. Further, the width W of the cover member 14 to be attached onto the water vapor barrier film is preferably 1 mm to 10 mm, and more preferably 1 mm to 5 mm from the viewpoint of water vapor barrier properties and strength. According to the cover member 14 having such a configuration, it is possible to prevent water vapor from entering the phosphor layer from the end of the water vapor barrier film, and to prevent deterioration of the phosphor in the phosphor layer. .

(Lighting device)
The lighting device of the present invention comprises the phosphor sheet of the present invention.
An example of the lighting device of the present invention will be described with reference to the drawings.
FIG. 2 is a schematic cross-sectional view showing an edge light type illumination device. As shown in FIG. 2, the illumination device diffuses blue light of the blue LED 31 and the blue LED 31 incident from the side, and a light guide plate 32 that emits uniform light on the surface, and phosphor that obtains white light from blue light A so-called "edge light type backlight" including the sheet 33 and the optical film 34 is configured.

The blue LED 31 constitutes a so-called "LED package" having an InGaN-based LED chip as a blue light emitting element. The light guide plate 32 uniformly emits light from the end face of a transparent substrate such as an acrylic plate. The phosphor sheet 33 is, for example, a phosphor sheet shown in FIG. The powder of the phosphor contained in the phosphor sheet 33 has an average particle diameter of several μm to several tens of μm. Thereby, the light scattering effect of the phosphor sheet 33 can be improved. The optical film 34 is made of, for example, a reflective polarizing film, a diffusion film, or the like for improving the visibility of the liquid crystal display device.

Further, FIG. 3 is a schematic cross-sectional view showing a direct type illumination device. As shown in FIG. 3, the lighting device includes a substrate 42 on which blue LEDs 41 are two-dimensionally arranged, a diffusion plate 43 for diffusing the blue light of the blue LEDs 41, and a distance from the substrate 42. A so-called "direct-type backlight" is provided, which includes a phosphor sheet 33 for obtaining the light intensity and an optical film 34.

The blue LED 41 constitutes a so-called "LED package" having, for example, an InGaN-based LED chip as a blue light emitting element. The substrate 42 is made of a glass cloth base material using a resin such as phenol, epoxy, polyimide, etc. On the substrate 42, blue LEDs 41 are equally spaced at a predetermined pitch, and two corresponding to the entire surface of the phosphor sheet 33. Placed in a dimension. In addition, the mounting surface of the blue LED 41 on the substrate 42 may be subjected to a reflection process as necessary. The substrate 42 and the phosphor sheet 33 are spaced apart by about 10 to 50 mm, and the illumination device constitutes a so-called "remote phosphor structure". The gap between the substrate 42 and the phosphor sheet 33 is held by a plurality of support columns and reflectors, and the support columns and reflectors are provided so as to surround the space formed by the substrate 42 and the phosphor sheet 33 in four directions. . The diffusion plate 43 diffuses the emitted light from the blue LED 41 in such a wide range that the shape of the light source can not be seen, and has a total light transmittance of, for example, 20% or more and 80% or less.

The present invention is not limited to the above-described embodiment, and it goes without saying that various updates can be added without departing from the scope of the present invention. For example, although the example which applied the illuminating device to the back light source for display apparatuses was shown in above-mentioned embodiment, you may apply to the light source for illumination. When applied to a light source for illumination, the optical film 34 is often unnecessary. The phosphor-containing resin may have not only a flat sheet shape but also a three-dimensional shape such as a cup shape.

Hereinafter, the present invention will be more specifically described by way of Examples and Comparative Examples, but the present invention is not limited thereto. In Examples, measurement of emission spectrum, calculation of various conversion efficiencies, and evaluation of crystallinity were performed as follows.

[Measurement of luminescence (PL) spectrum]
The emission peak wavelength, emission peak intensity, and emission half width in the PL spectrum were measured using an integrating sphere option of a spectrofluorimeter FP-6500 (manufactured by JASCO Corporation). The emission peak intensity was shown as a relative value based on PL spectrum data of a general YAG phosphor P46-Y3 material manufactured by Kasei Optronics.

[Calculation of various conversion efficiencies]
As the conversion efficiency of the phosphor, the efficiency of absorbing excitation light (absorptivity), the efficiency of converting absorbed excitation light into fluorescence (internal quantum efficiency), and the efficiency of converting excitation light as a product thereof into fluorescence (external Quantum efficiency was calculated. The luminescence characteristics were measured using an integrating sphere option of a spectrofluorimeter FP-6500 (manufactured by JASCO Corporation). The phosphor powder was filled in a dedicated cell, and blue excitation light with a wavelength of 450 nm was irradiated to measure the fluorescence spectrum. The quantum efficiency was calculated using the result from the quantum efficiency calculation software attached to the spectrofluorimeter.

[Evaluation of crystallinity]
Evaluation of crystallinity was performed by measurement of X-ray diffraction. The position (2θ) and half width of the diffraction peak in the X-ray diffraction (XRD) pattern of the CuKα ray were measured using a powder X-ray diffractometer (X'Pert PRO manufactured by PANalytical). Fitting was performed using the peak search function of the attached analysis software to analyze the characteristics of the XRD pattern of the phosphor.

Example 1
First, Ga ₂ O ₃ (purity 6N), Ba (NO ₃ ) ₂ (purity 3N), Sr (NO ₃ ) ₂ (purity 3N), and Eu (NO ₃ ) ₃ · nH ₂ O (purity 3N, n = 6.06) as well as ammonium sulfite monohydrate were prepared.
Then, as shown in Table 1, the composition formula _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x = 0.025, and y = 0.15 The weight values of the respective raw materials were calculated so that the composition ratio (Eu concentration: 2.5 mol%, Ba substitution ratio: 15%) was 0.1 molar amount. For Example 1, europium compounds _{_{_{(Eu (NO 3) 3 ·}}} nH 2 O) 1.115g, barium compound _{_{(Ba (NO 3) 2)}} 3.822g, and strontium compounds _{_{(Sr (NO 3) 2)}} 17 It is .539g.
A europium compound, a barium compound and a strontium compound were added to 300 ml of pure water, and the mixture was sufficiently stirred until the unsolved portion disappeared, to obtain a mixed solution containing Eu, Ba and Sr. Next, 18.744 g of a powdery gallium compound (powdery Ga ₂ O ₃ ) was added so that the molar amount of Ga was 2.0 times the sum of the molar amounts of Eu, Ba, and Sr. The mixture was sufficiently stirred to prepare a mixed solution of nitrate and gallium oxide powder.
Next, 15.4 g of ammonium sulfite having a number of moles of 1.15 times the total number of moles of Eu, Ba, and Sr was dissolved in 100 ml of pure water to prepare a sulfite solution.
The sulfite solution was added dropwise to the above mixed solution of nitrate and gallium oxide powder to obtain a precipitate / precipitate. The precipitate / precipitate is a mixture of europium sulfite, barium and strontium powder and gallium oxide powder.
Then, the precipitates were washed with pure water, filtered, and dried at 120 ° C. for 15 hours until the conductivity became 0.1 mS / cm or less. Then, a powder mixture containing Eu, Ba, Ga, and Sr was obtained by passing a wire mesh with a nominal opening of 100 μm. This powder mixture is a mixture containing europium sulfite-barium-strontium powder [powder composed of (Ba, Sr, Eu) SO ₃ ] and gallium oxide.
The powder mixture was then fired in an electric furnace. The firing conditions were as follows. The temperature was raised to 925 ° C. in 1.5 hours, then held at 925 ° C. for 1.5 hours, and then allowed to cool to room temperature in 2 hours. Hydrogen sulfide was flowed through the electric furnace at a rate of 0.3 liter / minute during firing. After that, passing through a mesh with a nominal opening of 25 μm, phosphor particles consisting of (Ba _y Sr _1-y ) ₁ -xGa ₂ S ₄ : Eu _x (x = 0.025, y = 0.15) were obtained. .
The above sample preparation method is described as a wet method in Table 1.

(Examples 2 to 7 and Comparative Examples 1 to 3)
As shown in Table 1, the composition formula _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x values of the examples and comparative examples, shown in y value The weight values of the respective raw materials were calculated so as to be 0.1 molar amount by the composition ratio. Other than this, a wet method in the same manner as in Example 1, the Examples, and Comparative Examples _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: to obtain phosphor particles consisting of Eu _x.

(Comparative example 4)
First, Ga ₂ O ₃ (purity 6N), BaCO ₃ (purity 3N), SrCO ₃ (purity 3N), and Eu ₂ O ₃ (purity 3N) were prepared.
Then, as shown in Table 1, the composition formula _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x = 0.10, and y = 0.35 The weight value of each raw material was calculated so as to be 0.05 molar amount at a composition ratio (Eu concentration: 10 mol%, Ba substitution ratio: 35%). In the case of Comparative Example 4, 0.8798 g of a europium compound (Eu ₂ O ₃ ), 4.318 g of a strontium compound (SrCO ₃ ), 3.108 g of a barium compound (BaCO ₃ ), and 9.372 g of a gallium compound (Ga ₂ O ₃ ) It is.
The europium compound, the strontium compound, the barium compound and the gallium compound were mixed in ethanol using a ball mill. After mixing was complete, the mixture was suction filtered and dried at 80 ° C. for 12 hours. Then, a powder mixture containing Eu, Sr, Ba, and Ga was obtained by passing a wire mesh having a nominal opening of 100 μm.
Next, the powder mixture was put in an alumina baking boat and baked in an electric furnace. The firing conditions were as follows. The temperature was raised to 925 ° C. in 1.5 hours, then held at 925 ° C. for 1.5 hours, and then allowed to cool to room temperature in 2 hours. Hydrogen sulfide was flowed through the electric furnace at a rate of 0.3 liter / minute during firing. After that, passing through a mesh with a nominal opening of 25 μm, phosphor particles consisting of (Ba _y Sr _{1 -y} ) ₁ -xGa ₂ S ₄ : Eu _x (x = 0.10, y = 0.35) were obtained. . The above-mentioned trial production method is described in Table 1 as a dry method.

In summary, prepared in Examples 1-7, the composition region of the phosphor, the composition ratio _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x It can be represented in the range of 0.025 to 0.20 and y = 0.15 to 0.49.

(Light emission evaluation result)
In Table 2, as the evaluation results of the light emission characteristics of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4, x of light emission peak wavelength, peak intensity, sample absorptivity, internal quantum efficiency, external quantum efficiency, CLE chromaticity x The y value, the luminance, and the full width at half maximum (FWHM) of light emission are shown.

As a result of measuring the PL spectrum for Example 1, an emission peak appears at a wavelength of 534 nm, the emission peak intensity is 2.50 (YAG ratio), the luminance is 141.1% (YAG ratio), and the emission half width is 49 nm. there were. Moreover, it was a CIEx, y chromaticity point (0.267, 0.688). In addition, as a result of calculating the conversion efficiency, the absorptivity was 64.2%, the internal quantum efficiency was 69.9%, and the external quantum efficiency was 44.9%.

Similarly, the evaluation results of the light emission characteristics of Examples 2 to 7 are also shown in Table 2.
The emission peak wavelength was 529 to 535 nm, the emission peak intensity was 2.46 to 3.64 (YAG ratio), the luminance was 124.7 to 187.0% (YAG ratio), and the emission half width was 48 to 50 nm. In addition, the CIEx, y chromaticity point showed coordinates in the range of (0.235, 0.695) to (0.271, 0.687). In addition, as a result of calculating the conversion efficiency, the absorptivity is 66.4 to 81.8%, the internal quantum efficiency is 64.6 to 79.0%, and the external quantum efficiency is 43.4 to 64.6%. .

Similarly, the evaluation results of the light emission characteristics of Comparative Examples 1 to 4 are also shown in Table 2.
The emission peak wavelength was 528 to 538 nm, the emission peak intensity was 1.25 to 3.43 (YAG ratio), the luminance was 68.1 to 192.7% (YAG ratio), and the emission half width was 48 to 54 nm. In addition, the CIEx, y chromaticity points became discrete coordinate positions in the range of CIEx value of 0.231 to 0.288 and CIEy value of 0.672 to 0.686. In addition, as a result of calculating the conversion efficiency, the absorptivity was 62.6 to 80.1%, the internal quantum efficiency was 37.6 to 75.3%, and the external quantum efficiency was 24.9 to 60.3%. .

When the evaluation results of the light emission characteristics of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4 are combined in light of the input composition ratio of Table 1, the peak wavelength becomes shorter as the Ba substitution ratio increases, and the Eu concentration As you increase the wavelength, you can see a rough trend that the wavelength becomes longer.
In addition, as shown in FIG. 4, when the emission peak wavelength is shortened, the emission peak intensity tends to decrease, and Examples 1 to 7 have relatively high emission intensity as compared with Comparative Examples 1 to 4. It can be said that the wavelength can be shortened while maintaining the The same tendency as that of the light emission peak intensity can be seen. Furthermore, in Examples 1 to 7, it can be seen that the internal quantum efficiency is high and the light emission characteristics are highly efficient as compared at the light emission wavelength of the same degree.

On the other hand, the CIEx, y chromaticity points are shown in FIG. 5 for Examples 1 to 7 and Comparative Examples 1 to 4. Examples 1 to 7 are indicated by “◆”, and Comparative examples 1 to 4 are indicated by “Δ”. Also, the Green chromaticity points (0.210, 0.710) of NTSC are indicated by "■". The chromaticity points of Examples 1 to 7 moved in the range of (0.271, 0.687) to (0.235, 0.695) almost on a single curve as the wavelength became shorter. Furthermore, since the CIE y values of Examples 1 to 7 are larger than Comparative Examples 1 to 4 and close to the Green chromaticity point of NTSC, it is understood that Examples 1 to 7 have higher green color purity.

Next, the crystallinity of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4 was evaluated by X-ray diffraction.
Table 3 shows the evaluation results of the crystallinity of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4. The X-ray diffraction patterns of Examples 1, 4, 5, 7 and Comparative Examples 1 to 4 are shown in FIG.
As a result of earnest analysis of the crystallinity evaluation results, it was found that the crystals of Examples 1 to 7 had unique crystal structures. Specifically, a diffraction peak appears at a diffraction angle 2θ of 30.0 to 30.4 °, and the relative intensity with respect to the maximum peak shows a certain range.
Looking at the X-ray diffraction pattern of Example 1 as shown in FIG. 6, the peak of the diffraction intensity maximum shows a diffraction peak belonging to the (422) plane of SrGaS ₂ S ₄ at the diffraction angle 2θ = 24.02 °. In the second peak of diffraction intensity, a diffraction peak belonging to the (444) plane appeared at a diffraction angle 2θ = 38.38 °. Further, at the diffraction angle 2θ = 30.0 to 30.40, a peak having a relative intensity of 8.8% with respect to the diffraction intensity maximum peak appeared at the position of 30.2 °.

Similarly, also in Examples 2 to 7 and Comparative Examples 1 to 4, the positions of peaks appearing at the diffraction intensity maximum and the second diffraction angle 2θ position, and the diffraction angle 2θ = 30.0 to 30.4 ° and the maximum peak The relative strengths to are summarized in Table 3.
In each of Examples 2 to 7, the peak of the diffraction intensity maximum appears a diffraction peak belonging to the (422) plane of SrGa ₂ S _{4 at} the diffraction angle 2θ = 23.82 to 23.96 °, and the _second diffraction intensity The diffraction peak belonging to the (444) plane appeared at the diffraction angle 2θ of 38.17 to 38.3 °. Further, at the diffraction angle 2θ of 30.0 to 30.4 °, a peak having a relative intensity of 7.7 to 14.8% with respect to the diffraction intensity maximum peak appeared at the position of 30.17 to 30.21 °. Among them, representative X-ray diffraction patterns of Examples 4, 5 and 7 are shown in FIG. 6, but the above-mentioned specific crystal structure can be confirmed.

On the other hand, in Comparative Example 1, the X-ray diffraction pattern is shown in FIG. 6, but the peak of the diffraction intensity maximum appears a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ at the diffraction angle 2θ of 24.06 °. The second peak of the diffraction intensity shows a diffraction peak belonging to the (444) plane at a diffraction angle 2θ of 38.42 °, but no peak appears at a diffraction angle 2θ of 30.0 to 30.4 ° . That is, Comparative Example 1 is the case of the composition ratio (Eu concentration: 10 mol%, Ba substitution ratio: 0%) where x = 0.10 and y = 0, and in this composition containing no Ba, the diffraction angle 2θ A distinctive diffraction peak of = 30.0-30.4 ° does not appear.

In Comparative Example 2, the X-ray diffraction pattern is shown in FIG. 6, but the peak of the diffraction intensity maximum appears at the diffraction angle 2θ = 34.36 °, and the second peak of the diffraction intensity appears at the diffraction angle 2θ = 17.00 °. It shows a structure different from the SrGa ₂ S ₄ structure, and no peak appears even at the diffraction angle 2θ of 30.0 to 30.4 °. That is, Comparative Example 2 is a case where the composition ratio (Eu concentration: 2.5 mo1%, Ba substitution ratio: 5%) in which x = 0.025, y = 0.05, and this composition having a small Ba substitution ratio In the above, the distinctive diffraction peak of the diffraction angle 2θ = 30.0 to 30.4 ° does not appear.

The X-ray diffraction pattern is shown in FIG. 6 in Comparative Example 3, but the peak at the maximum diffraction intensity is at the diffraction angle 2θ = 23.44 °, and the peak at the second diffraction intensity is at the diffraction angle 2θ = 31.82 It appears in ° and shows a structure different from the SrGa ₂ S ₄ structure. At the diffraction angle 2θ of 30.0 to 30.4 °, a peak having a relative intensity of 38.7% with respect to the diffraction intensity maximum peak appeared at the position of 30.15 °. That is, Comparative Example 3 is the case of the composition ratio (Eu concentration: 5 mol%, Ba substitution ratio: 55%) where x = 0.05 and y = 0.55, and in this composition, the second peak of the diffraction intensity Indicates a structure different from the SrGa ₂ S ₄ structure, and the Ba substitution ratio is too large, which suggests that the main structure is another structure in this composition.

In Comparative Example 4, the X-ray diffraction pattern is shown in FIG. 6, but the peak of the diffraction intensity maximum appears a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ at the diffraction angle 2θ of 24.06 °. In the second peak of intensity, a diffraction peak belonging to the (444) plane appears at a diffraction angle 2θ = 38.37 °, but no peak appears at a diffraction angle 2θ = 30.0 to 30.4 °. That is, Comparative Example 4 is the case of the composition ratio (Eu concentration: 10 mol%, Ba substitution ratio: 35%) where x = 0.10 and y = 0.35, and in this composition where the Ba substitution ratio is small, A distinctive diffraction peak of diffraction angle 2θ = 30.0 to 30.4 ° does not appear.

Summarizing the above results, the unique crystal structure found in Examples 1 to 7 can be defined under the following conditions.
The peak at the maximum diffraction intensity is a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ appearing at the diffraction angle 2θ = 23.7 to 24.1 °, and the _second peak of the diffraction intensity is the diffraction angle 2θ = It is a diffraction peak belonging to the (444) plane of SrGa ₂ S ₄ that appears in 38.1 to 38.5 °, and the relative intensity to the diffraction intensity maximum peak is 5 to 3 at a diffraction angle 2θ of 30.0 to 30.4 °. It is characterized by having a 20% diffraction peak.

Also seen in Examples 1-7, the specific crystal structure, composition formula _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x = 0.025 It is suggested to appear in the range of ̃0.20, y = 0.15 ̃0.49.

To summarize the above results, the phosphors produced in Examples 1 to 7 are
The composition formula _{_{_{(Ba y Sr 1-y)}}} 1-x Ga 2 S 4: in the phosphor represented by Eu _x,
It can be represented by a value in the range of x = 0.025 to 0.20, y = 0.15 to 0.49.

Furthermore, the unique crystal structure found in Examples 1-7 is defined under the following conditions.
The diffraction intensity maximum peak is a diffraction peak belonging to the (422) plane of SrGa ₂ S ₄ appearing at a diffraction angle 2θ of 23.7 ° to 24.1 °.
The second peak of the diffraction intensity is a diffraction peak belonging to the (444) plane of SrGa ₂ S ₄ which appears at a diffraction angle 2θ = 38.1 to 38.5 °.
A diffraction peak having a relative intensity of 5 to 20% relative to the diffraction intensity maximum peak at a diffraction angle 2θ of 30.0 to 30.4 °.

11 phosphor layer 12 first water vapor barrier film 13 second water vapor barrier film 14 cover member 141 substrate 142 adhesive

Claims

A phosphor comprising at least a phosphor represented by the following general formula (1) and satisfying the following conditions (1) to (3):
(Ba y Sr 1-y ) 1-x Ga 2 S 4 : Eu x ... general formula (1)
However, in the general formula (1), 0.025 ≦ x ≦ 0.20 and 0.15 ≦ y ≦ 0.49.
Condition (1): The diffraction intensity maximum peak of the XRD pattern is a diffraction peak belonging to the (422) plane of SrGa 2 S 4 appearing at the diffraction angle 2θ = 23.7 to 24.1 °.
Condition (2): The second peak of the diffraction intensity is a diffraction peak belonging to the (444) plane of SrGa 2 S 4 which appears at the diffraction angle 2θ = 38.1 to 38.5 °.
Condition (3): A diffraction peak having a relative intensity of 5 to 20% relative to the diffraction intensity maximum peak is present at a diffraction angle 2θ of 30.0 to 30.4 °.
The phosphor according to claim 1, wherein the y value of the fluorescent substance based on the CIE 1931 color system is 0.687 or more.
The phosphor according to any one of claims 1 to 2, wherein the internal quantum efficiency of the fluorescent substance is 0.64 or more.
A phosphor sheet comprising a phosphor layer containing the phosphor according to any one of claims 1 to 3 and a red phosphor.
A lighting device comprising the phosphor sheet according to claim 4.
A method for producing a phosphor, comprising the steps of: producing the phosphor according to any one of claims 1 to 3;
A barium sulfide, a strontium compound, and a europium compound are dissolved, and a first liquid containing a powdered gallium compound is mixed with a second liquid containing sulfite to form barium sulfite, strontium sulfite, and europium sulfite. A method for producing a phosphor, comprising a precipitation and precipitation step of obtaining a precipitate which is a mixture of the contained precipitate and the powdered gallium compound.
The method for producing a phosphor according to claim 6, further comprising a firing step of firing the precipitate under an atmosphere containing hydrogen sulfide.