JP4343267B1 - Green phosphor - Google Patents

Abstract

A green phosphor capable of increasing the internal quantum efficiency is provided.
A green phosphor containing a host crystal containing Sr, Ga and S and an emission center, and in the XRD pattern, the diffraction angle 2θ = the diffraction intensity of the maximum peak appearing at a diffraction angle 2θ = 21 to 27 °. A green phosphor characterized in that the ratio of the diffraction intensity of the maximum peak appearing at 14 to 20 ° is 0.4 or more.
[Selection] Figure 1

Description

  The present invention relates to a green phosphor. Specifically, it can be excited by a blue LED or a near-ultraviolet LED, used as an illumination phosphor, a liquid crystal backlight, FED (field emission display), PDP (plasma display), EL (electroluminescence), etc. The present invention relates to a green phosphor that can be used as a display phosphor.

  The current mainstream of light sources for illumination is fluorescent lamps and incandescent lamps, but those using LEDs (light-emitting diodes) as light sources consume less power and have longer lifespans than those of fluorescent lamps. It is not hot, so it is excellent in terms of safety and does not contain harmful substances such as mercury and is also excellent in terms of the environment. It is expected to become the mainstream of lighting light sources in the near future.

The current white LED is composed of a combination of a blue LED and YAG: Ce (yellow), but it is inferior in color rendering that exhibits a natural color development property. Even if it was illuminated with, it had a problem that it could not reproduce the color illuminated by natural light. Therefore, as a method for improving the color rendering properties of such current white LEDs, a combination of a near-ultraviolet LED and three types of phosphors of red, green and blue, or a blue LED and two types of phosphors of red and green, As a green phosphor used for this purpose, SrGa ₂ S ₄ : Eu is disclosed (see Patent Documents 1, 2, and 3).

JP 2002-060747 A JP 2007-056267 A JP 2007-214579 A

Conventionally disclosed green phosphors composed of SrGa ₂ S ₄ : Eu have had to further increase the luminous efficiency. In order to increase the luminous efficiency, it is said that it is important to use a phosphor having a high external quantum efficiency (= internal quantum efficiency × absorption rate). However, for example, as described above, when white light is obtained by combining a near-ultraviolet LED, a blue LED, and a phosphor including a green phosphor, the phosphor absorbs the light emitted from the LED and the light of this LED. In order to obtain white light in combination with emitted light, it is necessary to appropriately transmit the light emitted by the LED. Therefore, in such applications, it is necessary to increase the external quantum efficiency by increasing the internal quantum efficiency of the phosphor, or to increase the emission intensity of the phosphor.

  Therefore, the present invention intends to provide a green phosphor having a higher internal quantum efficiency.

  The present invention is a green phosphor containing a host crystal containing Sr, Ga and S and an emission center, and in an XRD pattern using CuKα rays, a maximum peak appearing at a diffraction angle 2θ = 21 to 27 °. A green phosphor is proposed in which the ratio of the diffraction intensity of the maximum peak appearing at a diffraction angle 2θ = 14 to 20 ° with respect to the diffraction intensity is 0.4 or more.

  In the XRD pattern, the ratio of the maximum peak diffraction intensity appearing at the diffraction angle 2θ = 14 to 20 ° to the maximum peak diffraction intensity appearing at the diffraction angle 2θ = 21 to 27 ° in the XRD pattern is significantly high. And, for example, a combination of a near-ultraviolet LED or a blue LED as an excitation source and a phosphor containing the green phosphor of the present invention provides a white light emitting device or device. When configured, the internal quantum efficiency is high, so the light emission efficiency is high, and more sufficient white light can be obtained. In addition, even when a limited amount of green phosphor is combined with an LED having limited characteristics, a sufficient amount of light emission can be obtained.

Horizontal axis: Ratio of diffraction intensity of maximum peak appearing at 2θ = 14 to 20 ° to diffraction intensity of maximum peak appearing at 2θ = 21 to 27 ° (400) / (422), vertical axis: internal quantum efficiency (%) It is the figure which plotted the value of the fluorescent substance powder obtained in Example 1-12 and Comparative Example 1-6 on the coordinate which consists of. Moreover, the dotted line shown in the figure is a value calculated from the diffraction intensity shown in the standard sample (00-025-0895) of the International Diffraction Data Center (ICDD) ((400) / (422) = 0.54). It is. Horizontal axis: ratio of diffraction intensity of maximum peak appearing at 2θ = 32 to 37 ° to diffraction intensity of maximum peak appearing at 2θ = 36 to 42 ° (642) / (444), vertical axis: internal quantum efficiency (%) It is the figure which plotted the value of the fluorescent substance powder obtained in Example 1-12 and Comparative Example 1-6 on the coordinate which consists of. Moreover, the dotted line shown in the figure is a value calculated from the diffraction intensity shown in the standard sample (00-025-0895) of the International Diffraction Data Center (ICDD) ((642) / (444) = 2.2) It is. Horizontal axis: Ratio of diffraction intensity of maximum peak appearing at 2θ = 21 to 27 ° to diffraction intensity of maximum peak appearing at 2θ = 27 to 34 ° (422) / (062), vertical axis: Internal quantum efficiency (%) It is the figure which plotted the value of the fluorescent substance powder obtained in Example 1-12 and Comparative Example 1-6 on the coordinate which consists of. Moreover, the dotted line shown in the figure is a value calculated from the diffraction intensity shown in the standard sample (00-025-0895) of the International Diffraction Data Center (ICDD) ((422) / (062) = 2.6). It is. A SrS-Ga ₂ S ₃ phase diagram. 10 is an XRD pattern of Example 7. FIG. 10 is an XRD pattern of Comparative Example 3.

BEST MODE FOR CARRYING OUT THE INVENTION

  Embodiments of the present invention will be described in detail below, but the scope of the present invention is not limited to the embodiments described below.

The green phosphor according to the present embodiment (hereinafter referred to as “the present green phosphor”) is a green phosphor obtained by doping a host crystal containing Sr, Ga and S with Eu ²⁺ as the emission center. Is a phosphor containing a crystal represented by the general formula SrGa ₂ S ₄ : Eu ²⁺ .

At this time, it is preferable that the emission center (luminescent ion) of the green phosphor is one containing divalent Eu ²⁺ , in particular, only divalent Eu ²⁺ . The emission wavelength (color) of Eu ²⁺ strongly depends on the mother crystal and is known to exhibit various wavelengths depending on the mother crystal. A spectrum can be obtained.
The concentration of Eu ²⁺ is preferably 0.1 to 10 mol% of the concentration of Sr in the mother crystal, preferably 0.5 to 7 mol%, and more preferably 1 to 5 mol%.
It should be noted that the same effect can be expected even if an ion other than Eu ²⁺ , for example, one or more ions selected from the group consisting of rare earth ions and transition metal ions is used as the luminescent center (luminescent ion). Can do. Examples of rare earth ions include ions such as Sc, Tb, Er, and Ce. Examples of transition metal ions include ions such as Mn, Cu, Ag, Cr, and Ti.

The green phosphor may be a single phase of SrGa ₂ S ₄ : Eu ²⁺ or may contain an impurity phase. That is, in the SrS-Ga ₂ S ₃ system phase diagram (see FIG. 4), the liquid was cooled after reaching “liquid phase + SrGa ₂ S ₄ ”, and in particular, “liquid phase + SrGa ₂ S in the region of 50 mol% or more of Ga ₂ S _{3. Since} it is preferably cooled after reaching ₄ ", it may contain an impurity phase formed by cooling the liquid phase component.

Further, according to the stoichiometric composition represented by SrGa ₂ S ₄ , it contains Ga at a ratio of 2.00 mol with respect to 1.0 mol of Sr. As described above, the green phosphor is composed of SrGa ₂ S _4. : It may be a single phase of Eu ^{2+ or} may contain an impurity phase, and in particular, one that has been cooled after reaching “liquid phase + SrGa ₂ S ₄ ” in a region of 50 mol% or more of Ga ₂ S ₃ Since it is preferable, this green phosphor includes a case where Ga is excessively contained by a predetermined amount rather than the stoichiometric composition represented by SrGa ₂ S ₄ . Under the present circumstances, it is preferable to contain Ga excessively so that the molar ratio (Ga / Sr) of Ga content with respect to Sr content may be set to 2.02-3.02. In particular, the lower limit value is 2.02 or more, particularly preferably 2.21 or more, and the upper limit value is preferably 2.72 or less, particularly preferably 2.45 or less.
However, it is not necessarily limited to what contains Ga more excessively than the stoichiometric composition shown by SrGa ₂ S ₄ . This is because, as will be described later, there is a method for obtaining the green phosphor other than containing Ga excessively.

(Characteristics by X-ray diffraction)
This green phosphor has a diffraction angle 2θ = 14 to 20 with respect to the maximum peak diffraction intensity appearing at a diffraction angle 2θ = 21 to 27 ° in an XRD pattern using CuKα rays measured by an X-ray diffractometer (XRD). It is important that the ratio (400) / (422) of the diffraction intensity of the maximum peak appearing at ° is 0.4 or more.
Note that the maximum peak appearing at 2θ = 21 to 27 ° is assumed to be a diffraction peak of (422) plane in consideration of ICDD 00-025-0895, and the maximum peak appearing at 2θ = 14 to 20 ° is ICDD 00-025 If -0895 is taken into account, it is assumed that the diffraction peak is on the (400) plane, and therefore this ratio is also expressed as (400) / (422) in this specification.
It has been found that if (400) / (422) is 0.4 or more, the internal quantum efficiency is increased.
From this viewpoint, (400) / (422) of the green phosphor is preferably 0.4 or more and 3 or less, and the lower limit value is preferably 0.45 or more, particularly 0.6 or more. Is preferred. On the other hand, the upper limit is preferably 2.8 or less, and particularly preferably 2.5 or less.

The ratio (642) / (444) of the maximum peak diffraction intensity appearing at the diffraction angle 2θ = 32 to 37 ° to the maximum peak diffraction intensity appearing at the diffraction angle 2θ = 36 to 42 ° is 0.7 or more. Is preferred.
The maximum peak appearing at 2θ = 36 to 42 ° is assumed to be a diffraction peak of (444) plane in consideration of ICDD 00-025-0895, and the maximum peak appearing at 2θ = 32 to 37 ° is ICDD 00-025. When -0895 is taken into account, it is assumed that the diffraction peak is on the (642) plane. Therefore, in this specification, the ratio is also expressed as (642) / (444).
It has been found that if (642) / (444) is 0.7 or more, the internal quantum efficiency is increased.
From this point of view, (642) / (444) of the green phosphor is preferably 0.7 or more and 15.0 or less, and the lower limit is 1.0 or more, particularly 1.5 or more. The upper limit is preferably 12.0 or less, and particularly preferably 10.0 or less.

The ratio (422) / (062) of the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 21 to 27 ° to the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 27 to 34 ° is 2.6 or more. Is preferred.
The maximum peak appearing at 2θ = 27 to 34 ° is assumed to be a diffraction peak of (062) plane in consideration of ICDD 00-025-0895, and the maximum peak appearing at 2θ = 21 to 27 ° is ICDD 00-025 Since -0895 is considered to be a diffraction peak of (422) plane, in this specification, the ratio is also expressed as (422) / (062).
It has been found that if (422) / (062) is 2.6 or more, the internal quantum efficiency is increased.
From this viewpoint, (422) / (062) of the green phosphor is preferably 2.6 or more and 8.0 or less, more preferably a lower limit value of 2.8 or more, and particularly preferably 3.0 or more. The upper limit is 7.0 or less, particularly 6.5 or less.

(Features of this green phosphor)
The green phosphor is excited by light having a wavelength in the near ultraviolet region to the blue region (about 300 nm to 510 nm) and emits green light.

With regard to the emission spectrum of the present green phosphor, it has an emission peak in the region of wavelengths of 502 nm ± 30 nm to 557 nm ± 30 nm by photoexcitation at a wavelength of about 300 nm to 510 nm.
In addition, if this green fluorescent substance is the same composition, even if it excites with any wavelength of the near ultraviolet region-blue region wavelength (about 300 nm-510 nm), the point that the width and position of the emission spectrum do not change. There is one feature.

  Speaking of CIE chromaticity coordinates, this green phosphor is expressed by x = 0.05 to 0.40 and y = 0.50 to 0.80 by substituting a part of Sr with Ca and Ba. Green light, especially x = 0.15 to 0.35, y = 0.60 to 0.75, especially x = 0.25 to 0.33, y = 0.65 to 0.73 The indicated green light can be emitted.

(Production method)
Next, an example of a preferable method for producing the green phosphor will be described. However, it is not limited to the manufacturing method demonstrated below.

  In this green phosphor, raw materials such as Sr raw material, Ga raw material, S raw material and Eu raw material are weighed and mixed, fired at 900 to 1400 ° C. in a reducing atmosphere, and crushed with a stamp mill or a rough machine. It can be obtained by classifying with a sieve or the like, annealing as necessary, preferably by further precipitating in a non-aqueous organic solvent such as ethanol or water, and drying the supernatant.

  In such a production method, in order to obtain the above-described characteristics by X-ray diffraction, for example, Ga is added in excess of the stoichiometric composition, the firing temperature is adjusted, the flux is blended and fired, or annealing is performed. The method of doing is conceivable.

Examples of the Sr material include strontium salts such as double oxides and carbonates in addition to the oxide of Sr. Examples of the Ga material include gallium salts such as Ga ₂ O ₃ .
Examples of the S raw material include SrS, S, BaS, SiS ₂ , Ce ₂ S ₃ , and H ₂ S gas.
Examples of the Eu raw material include europium compounds (Eu salts) such as EuF ₃ , Eu ₂ O ₃ and EuCl ₃ .

At this time, according to the stoichiometric composition represented by SrGa ₂ S ₄ , it is common to manufacture by mixing 2.00 mol of Ga with respect to 1.0 mol of Sr. In this case, Ga may be mixed and contained by a predetermined amount in excess of the stoichiometric composition represented by SrGa ₂ S ₄ . Specifically, the molar ratio of the Ga content to the Sr content (Ga / Sr) is 2.02 to 3.02, particularly 2.02 to 2.72, especially 2.21 to 2.45. It may be contained in excess of Ga to such an extent that
Thus, the characteristic by X-ray diffraction as described above can also be obtained by increasing the molar ratio (Ga / Sr) of the Ga content to the Sr content from 2.00.

Further, the above-mentioned characteristics by X-ray diffraction can be obtained also by adding a flux such as MgCl ₂ , CaCl ₂ , NaCl ₂ , NaCl, KCl, KI, SrF ₂ , EuF ₃ .

In order to improve color rendering properties, rare earth elements such as Pr and Sm may be added to the raw material as a color adjusting agent.
In order to improve excitation efficiency, one or more elements selected from rare earth elements such as Sc, La, Gd, and Lu may be added to the raw material as a sensitizer.
However, these addition amounts are preferably 5 mol% or less with respect to Sr. When the content of these elements exceeds 5 mol%, a large amount of heterogeneous phases are precipitated, and the luminance may be remarkably lowered.
Further, alkali metal elements, monovalent cation metals such as Ag ⁺ , and halogen ions such as Cl ⁻ , F ⁻ and I ⁻ may be added to the raw material as charge compensators. The amount added is preferably about the same as the content of aluminum group or rare earth group in terms of charge compensation effect and luminance.

Mixing of the raw materials may be performed either dry or wet.
In the case of dry mixing, the mixing method is not particularly limited. For example, zirconia balls may be used as a medium, mixed with a paint shaker or a ball mill, and dried as necessary to obtain a raw material mixture. .
In the case of wet mixing, the raw material is in a suspension state, and after mixing with a paint shaker or a ball mill using zirconia balls as the medium, the medium is separated with a sieve, and dried under reduced pressure, vacuum dried, or sprayed. Water may be removed from the suspension by an appropriate drying method such as drying to obtain a dry raw material mixture.

  Before firing, the raw material mixture obtained as described above may be pulverized, classified and dried as necessary. However, crushing, classification, and drying are not necessarily performed.

Firing is preferably performed at 1000 ° C. to 1400 ° C.
As the firing atmosphere at this time, a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide atmosphere containing carbon monoxide, an atmosphere of hydrogen sulfide, carbon disulfide, other inert gas or reducing gas, etc. are adopted. Of these, firing in a hydrogen sulfide atmosphere is preferable.
The characteristics by X-ray diffraction can also be adjusted by the firing temperature. For example, when less Ga is blended than the stoichiometric composition represented by SrGa ₂ S _4, it is preferable to fire at 1100 ° C. or higher, particularly 1150 ° C. or higher. In addition, when Ga is added in excess of the stoichiometric composition represented by SrGa ₂ S _4, it is preferably fired at 1000 ° C. or higher, particularly 1050 ° C. or higher.
The upper limit of the firing temperature is determined by the durability temperature of the firing furnace, the decomposition temperature of the product, etc., but in the method for producing the green phosphor, firing at 1000 to 1200 ° C. is particularly preferable. Moreover, although baking time is related with baking temperature, it is preferable to adjust suitably within the range of 2 hours-24 hours.

In the above firing, when the raw material mixture does not contain a sulfur raw material, it is preferably fired in an atmosphere of hydrogen sulfide or carbon disulfide. However, when the raw material mixture contains a sulfur raw material, it can be fired in an atmosphere of hydrogen sulfide, carbon disulfide, or an inert gas. In this case, hydrogen sulfide and carbon disulfide may become a sulfur compound, and also have a function of suppressing decomposition of the product.
On the other hand, when hydrogen sulfide or carbon disulfide is used in the firing atmosphere, these compounds are also sulfur compounds. For example, when BaS is used as a raw material component, a barium compound and a sulfur compound are used. .

In the production of the present green phosphor, it is preferable that after firing, it is crushed with a stamp mill, a rough machine, a paint shaker or the like, and then classified with a sieve or the like. When crushing, it is preferable to adjust the crushing time so that the particle size does not become too fine.
In the classification using a sieve or the like, it is preferable to classify so as to cut a particle size larger than 150 μm, particularly a particle size larger than 130 μm, especially a particle size larger than 110 μm. Further, it is preferable to classify so as to cut a particle size smaller than 2 μm, particularly smaller than 3 μm, especially smaller than 4 μm.

The characteristics by X-ray diffraction as described above can also be obtained by annealing after crushing as described above.
As the atmosphere for annealing, a nitrogen gas atmosphere containing a small amount of hydrogen gas, a carbon dioxide atmosphere containing carbon monoxide, an atmosphere of hydrogen sulfide, carbon disulfide, other inert gas or reducing gas, etc. are adopted. Among these, annealing in a hydrogen sulfide atmosphere is preferable.
As the annealing temperature, for example, when Ga is blended less than the stoichiometric composition represented by SrGa ₂ S _4, it is preferable to anneal at 1100 ° C. or more, particularly 1150 ° C. or more. Further, when Ga is added in excess of the stoichiometric composition represented by SrGa ₂ S _4, it is preferable to anneal at 1000 ° C. or higher, particularly 1050 ° C. or higher.
The upper limit of the annealing temperature is determined by the durability temperature of the furnace, the decomposition temperature of the product, etc., but in the method for producing the green phosphor, it is particularly preferable to anneal at 1000 to 1200 ° C. Moreover, although annealing time is related with annealing temperature, it is preferable to adjust suitably within the range of 1 hour-10 hours.

  Furthermore, it is preferable to put in a non-aqueous organic solvent such as ethanol or water, stir while applying ultrasonic vibration, and let stand, collect the precipitate except for the supernatant, and then dry. By this final solvent precipitation classification treatment, the internal quantum efficiency and the external quantum efficiency can be remarkably increased.

(Use)
The green phosphor can be combined with an excitation source to form a green light emitting element or device, and can be used for various applications. For example, in addition to general illumination, it can be used for special light sources, liquid crystal backlights, display devices such as EL, FED, and CRT display devices.

As an example of a green light emitting element or device that combines the green phosphor and an excitation source that can excite the green phosphor, for example, in the vicinity of a light emitter that generates light having a wavelength of 300 nm to 510 nm (that is, purple light to blue light), that is, The green phosphor can be configured at a position where the light emitted from the light emitter can be received. Specifically, a phosphor layer made of the green phosphor may be laminated on a light emitter layer made of a light emitter.
At this time, the phosphor layer is prepared by, for example, adding the powdery green phosphor together with a binder to an appropriate solvent, thoroughly mixing and dispersing uniformly, and applying the obtained coating liquid to the surface of the light emitting layer. What is necessary is just to make it apply | coat and dry and form a coating film (phosphor layer).
Alternatively, the phosphor layer can be formed by kneading the green phosphor into a glass composition or a resin composition and dispersing the green phosphor in the glass layer or the resin layer.
Furthermore, the green phosphor may be formed into a sheet shape, and this sheet may be laminated on the phosphor layer, or the green phosphor may be directly sputtered onto the phosphor layer to form a film. You may do it.

  Further, a white light emitting element or device can be configured by combining the green phosphor, the red phosphor, the blue phosphor as necessary, and an excitation source that can excite them, for example, for general illumination. In addition, it can be used for special light sources, liquid crystal backlights, display devices such as EL, FED, and CRT display devices.

As an example of a white light emitting element or device configured by combining the green phosphor, the red phosphor, the blue phosphor as necessary, and an excitation source capable of exciting these, for example, light having a wavelength of 300 nm to 510 nm The green phosphor is disposed in the vicinity of a light emitter that generates (i.e., purple light to blue light), i.e., a position where the light emitted from the light emitter can be received, and a red phosphor and, if necessary, a blue phosphor It can comprise by arrange | positioning.
Specifically, a phosphor layer made of the green phosphor, a phosphor layer made of a red phosphor, and a phosphor layer made of a blue phosphor if necessary. What is necessary is just to laminate | stack.
In addition, the powdery green phosphor, red phosphor and, if necessary, the blue phosphor are added to a suitable solvent together with a binder, mixed thoroughly and dispersed uniformly, and the resulting coating solution is What is necessary is just to make it apply | coat and dry on the surface of a light emitting layer, and to form a coating film (phosphor layer).
Further, the green phosphor, the red phosphor and, if necessary, the blue phosphor are kneaded into a glass composition or a resin composition so that the phosphor is dispersed in the glass layer or the resin layer. Layers can also be formed.
In addition, a phosphor layer formed by kneading the green phosphor and the red phosphor in a resin may be formed on an excitation source composed of a blue LED or a near ultraviolet LED.
Furthermore, the green phosphor, the red phosphor and, if necessary, the blue phosphor may be formed into a sheet shape, and this sheet may be laminated on the phosphor layer. The phosphor and the red phosphor may be directly sputtered onto the phosphor layer to form a film.

(Glossary of terms)
In the present invention, the “light emitting element” in the “green light emitting element or apparatus” or “white light emitting element or apparatus” is a light emitting element that emits a relatively small light and includes at least a phosphor and a light emitting source as its excitation source. A device is intended, and a “light-emitting device” is intended to mean a light-emitting device that emits a relatively large amount of light and includes at least a phosphor and a light-emitting source as its excitation source.
In the present invention, when “X to Y” (X and Y are arbitrary numbers) is described, it means “preferably greater than X” or “preferably greater than Y” with the meaning of “X to Y” unless otherwise specified. The meaning of “small” is also included.
Further, when “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), the intention of “preferably larger than X” or “preferably smaller than Y” Is included.

  Hereinafter, the present invention will be described based on examples. However, the present invention is not construed as being limited to these.

<XRD measurement>
The phosphor powder obtained in Example 1-12 and Comparative Example 1-6 was used as a sample for X-ray diffraction, and this sample was mounted on a holder and MXP18 (Bruker AXS Co., Ltd.) was used. Then, the angle and intensity of the diffraction line were measured under the following conditions.

(Tube) CuKα ray (Tube voltage) 40 kV
(Tube current) 150 mA
(Sampling interval) 0.02 °
(Scanning speed) 4.0 ° / min
(Starting angle) 5.02 °
(End angle) 80 °

<Measurement of absorption rate, internal quantum efficiency and external quantum efficiency>
For the phosphor powders obtained in Example 1-12 and Comparative Example 1-6, the absorptance, internal quantum efficiency, and external quantum efficiency were measured as follows.
A spectrofluorophotometer FP-6500 and an integrating sphere unit ISF-513 (manufactured by JASCO Corporation) were used and the calculation was performed according to a solid quantum efficiency calculation program. The spectrofluorometer was corrected using a sub-standard light source and rhodamine B.
Formulas for calculating the absorption rate, internal quantum efficiency, and external quantum efficiency of the SrGa ₂ S ₄ : Eu phosphor when the excitation light is 466 nm are shown below.

<Measurement of PL emission spectrum and CIE chromaticity coordinates>
About the phosphor powder obtained in Example 1-12 and Comparative Example 1-6, a PL (photoluminescence) spectrum was measured using a spectrofluorometer (manufactured by Hitachi, F-4500), and PL emission intensity was measured. Asked.
Moreover, the luminance emission color (CIE chromaticity coordinate xy value) was obtained from the PL emission spectrum.

Example 1
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 1.98, so as to be 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1130 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 2)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.00, so that it becomes 1.0 mol% with respect to Sr. EuS was mixed with MgCl ₂ as a flux so as to be 0.5 wt% with respect to SrGa ₂ S ₄ , and Φ ₃ mm zirconia balls were used as media and mixed for 100 minutes with a paint shaker. The resulting mixture was calcined at 1100 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 3)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.15, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 6 hours in a hydrogen sulfide atmosphere. Next, the fired product was crushed for 1 minute with a rakai machine (“ALM-360T” manufactured by Nissho Scientific Co., Ltd.), further annealed at 1100 ° C. for 4 hours in an argon atmosphere, and a mesh size of 140 mesh And a 440-mesh sieve were used to collect the mesh under the 140-mesh sieve and the top of the 440-mesh sieve to obtain phosphor powder (sample).

(Example 4)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.00, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 2 hours in a hydrogen sulfide atmosphere. Next, the fired product was crushed for 1 minute with a rakai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), further annealed at 1150 ° C. for 2 hours in an argon atmosphere, and a mesh size of 140 mesh And a 440-mesh sieve were used to collect the mesh under the 140-mesh sieve and the top of the 440-mesh sieve to obtain phosphor powder (sample).

(Example 5)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.00, so that it becomes 1.0 mol% with respect to Sr. EuS was blended with KI as a flux so as to be 0.5 wt% with respect to SrGa ₂ S ₄ , and Φ3 mm zirconia balls were used as media and mixed for 100 minutes with a paint shaker. The resulting mixture was calcined at 1180 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 6)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.21, so as to be 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 7)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 3.02, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1150 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichito Kagaku Co., Ltd.), and using a 140 mesh and 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 8)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.00, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1190 ° C. for 6 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

Example 9
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.72, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1050 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Example 10)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.45, and 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichito Kagaku Co., Ltd.), and using a 140 mesh and 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

Example 11
SrS, Ga ₂ S ₃ and EuS are used as starting materials, SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.45, and 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a rakai machine (“ALM-360T” manufactured by Nisto Kagaku Co., Ltd.), and further annealed at 1100 ° C. in a hydrogen sulfide atmosphere for 4 hours. Using a mesh and a 440 mesh sieve, the mesh was collected under the 140 mesh mesh and on the 440 mesh sieve to obtain phosphor powder (sample).

Example 12
SrS, Ga ₂ S ₃ and EuS are used as starting materials, SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.45, and 1.0 mol% with respect to Sr. EuS was blended, and zirconia balls with a diameter of 3 mm were used as media and mixed for 100 minutes with a paint shaker. The resulting mixture was fired at 1200 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was crushed for 1 minute with a rakai machine (“ALM-360T” manufactured by Nisto Kagaku Co., Ltd.), further annealed at 1150 ° C. for 6 hours in an argon atmosphere, and 140 mesh openings And a 440-mesh sieve were collected under a 140-mesh sieve and on a 440-mesh sieve. Furthermore, the powder collected in this manner was placed in a 99.5% ethanol solution (25 ° C.) and stirred, and ultrasonic waves (“W-113” manufactured by Honda Electronics Co., Ltd.) were applied in the order of 28 kHz, 45 kHz, and 100 kHz. After dispersing and allowing to stand for 30 seconds, only the sediment that had been removed except the supernatant was collected and dried for 10 minutes with a dryer (100 ° C.) to obtain a phosphor powder (sample).

(Comparative Example 1)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 1.95, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 2 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Comparative Example 2)
A phosphor powder (sample) was obtained in the same manner as in Comparative Example 1 except that SrS and Ga ₂ S ₃ were blended so that the atomic ratio of Ga / Sr was 2.00.

(Comparative Example 3)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, and SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 2.00, so that it becomes 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 1100 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a rakai machine (“ALM-360T” manufactured by Nisto Kagaku Co., Ltd.), and further annealed at 1050 ° C. for 2 hours in a hydrogen sulfide atmosphere. Using a mesh and a 440 mesh sieve, the mesh was collected under the 140 mesh mesh and on the 440 mesh sieve to obtain phosphor powder (sample).

(Comparative Example 4)
SrS, Ga ₂ S ₃ and EuS are used as starting materials, SrS and Ga ₂ S ₃ are blended so that the atomic ratio of Ga / Sr is 4.00, and 1.0 mol% with respect to Sr. EuS was blended in, and mixed with a paint shaker for 100 minutes using φ3 mm zirconia balls as media. The resulting mixture was calcined at 950 ° C. for 4 hours in a hydrogen sulfide atmosphere. Next, the fired product was pulverized for 1 minute with a raibai machine (“ALM-360T” manufactured by Nichido Kagaku Co., Ltd.), and using a 140 mesh mesh and a 440 mesh sieve, The top of the sieve having a mesh size of 440 mesh was collected under the sieve to obtain a phosphor powder (sample).

(Comparative Example 5)
A phosphor powder (sample) was obtained in the same manner as in Comparative Example 4 except that SrS and Ga ₂ S ₃ were blended so that the atomic ratio of Ga / Sr was 2.00.

(Comparative Example 6)
A phosphor powder (sample) was obtained in the same manner as in Comparative Example 4 except that SrS and Ga ₂ S ₃ were blended so that the atomic ratio of Ga / Sr was 2.30.

(Discussion)
When the excitation spectrum and the emission spectrum were measured for the phosphor powders obtained in Example 1-12 and Comparative Example 1-6, they were sufficiently excited and excited by light having a wavelength of 300 nm to 510 nm (that is, purple light to blue light). Since two peaks were observed in the spectrum, it was confirmed that the spectrum was more fully excited by near ultraviolet light and blue light.
In addition, the light emission peak position within a wavelength range of 502 nm ± 30 nm to 557 nm ± 30 nm is shown, and green light with a CIE chromaticity coordinate x = 0.05 to 0.40 and y = 0.50 to 0.80 is emitted. It was confirmed.

As a representative example of the XRD pattern of Example 1-12, the XRD pattern of Example 7 is shown in FIG. 5, and the XRD pattern of Comparative Example 3 is shown in FIG. 6 as a comparison.
Compared to the XRD pattern of Comparative Example 3 and the normal green phosphor (SrGa ₂ S ₄ ), the XRD pattern of the green phosphor (Example 1-12) has diffraction angles 2θ = 14 to 20 ° and 2θ = 32 It was found that the diffraction intensity of the maximum peak appearing at ˜37 ° is large, whereas the diffraction intensity of the maximum peak appearing at 2θ = 21 to 27 °, 27 to 34 ° and 36 to 42 ° is small.
Therefore, the ratio of the diffraction intensity of the maximum peak appearing at 2θ = 14-20 ° to the diffraction intensity of the maximum peak appearing at 2θ = 21-27 ° (400) / (422), and the maximum peak appearing at 2θ = 36-42 °. Ratio of diffraction intensity of maximum peak appearing at 2θ = 32 to 37 ° with respect to diffraction intensity (642) / (444), or appearing at 2θ = 21 to 27 ° with respect to diffraction intensity of maximum peak appearing at 2θ = 27 to 34 ° It is considered that the characteristics of the green phosphor can be shown by the ratio (422) / (062) of the diffraction intensity of the maximum peak.

1 that Example 1-12 has a significantly higher (400) / (422) and higher internal quantum efficiency than Comparative Example 1-6. It turned out that especially Examples 2-12 become internal quantum efficiency 71% or more, and especially Examples 7-12 become internal quantum efficiency 75% or more especially.
Further, in Example 2-12, (400) / (422) was found to be significantly higher than the standard sample (00-025-0895, SrGa ₂ S ₄ ) of the International Diffraction Data Center (ICDD). did.
From this viewpoint, (400) / (422) of the green phosphor is preferably 0.40 or more, particularly 0.45 or more, and more preferably 0.6 or more. Moreover, since it will be hard to melt | dissolve and become a powder when the upper limit exceeds 3, it is considered to be preferably 3 or less.

2 that Example 1-12 has higher internal quantum efficiency and (642) / (444) is significantly higher than Comparative Example 1-6.
From this viewpoint, (642) / (444) of the green phosphor is preferably 0.70 or more, particularly 1.0 or more, and more preferably 1.5 or more. Moreover, since it will be hard to melt | dissolve and become a powder when 10.0 is exceeded, it is thought that it is preferable that it is 10.0 or less.

From FIG. 3, it was found that Example 1-12 had significantly higher (422) / (062) and higher internal quantum efficiency than Comparative Example 1-6.
Moreover, none of the Examples 1-12, standard sample (00-025-0895, SrGa ₂ S ₄₎ of the International Center for Diffraction Data (ICDD) as compared with and found to be high (422) / (062) .
From this viewpoint, (422) / (062) of the present green phosphor is preferably 2.6 or more, particularly 2.8 or more, and particularly preferably 3.0 or more. Moreover, since it was hard to melt | dissolve and become a powder when an upper limit exceeds 8.0, it turned out that it is especially preferable that it is 8.0 or less.

Examining the test results so far, among the green phosphors, those cooled after reaching the “liquid phase + SrGa ₂ S ₄ ” in the SrS—Ga ₂ S ₃ phase diagram (see FIG. 4), In particular, it is considered preferable to be cooled after reaching “liquid phase + SrGa ₂ S ₄ ” in a region of 50 mol% or more of Ga ₂ S ₃ from the viewpoint of increasing the internal quantum efficiency.

Claims (6)

  A green phosphor containing a host crystal containing Sr, Ga and S and an emission center, and in the XRD pattern using CuKα rays, the diffraction intensity of the maximum peak appearing at a diffraction angle 2θ = 21 to 27 ° A green phosphor, wherein the ratio of the diffraction intensity of the maximum peak appearing at a diffraction angle 2θ = 14 to 20 ° is 0.4 or more.   The ratio of the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 32 to 37 ° to the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 36 to 42 ° is 0.7 or more. Green phosphor.   The ratio of the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 21 to 27 ° to the diffraction intensity of the maximum peak appearing at the diffraction angle 2θ = 27 to 34 ° is 2.6 or more. 2. The green phosphor according to 2. The green phosphor according to any one of claims 1 to 3, wherein Eu ²⁺ is contained as an emission center.   The green light emitting element thru | or apparatus provided with the excitation source and the green fluorescent substance in any one of Claims 1-3.   The white light emitting element thru | or apparatus provided with the excitation source, the green fluorescent substance in any one of Claims 1-3, and a red fluorescent substance.

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