JP7748119B2 - Phosphor, its manufacturing method, and light-emitting device - Google Patents

Description

The present invention relates to a phosphor containing Eu in a crystal represented by Na ₅ Al ₃ F ₁₄ or a crystal having the same crystal structure as Na 5 Al 3 F 14, a method for producing the phosphor, and a light-emitting device.

Phosphors are used in vacuum fluorescent displays (VFDs (Vacuum-Fluorescent Displays)), field emission displays (FEDs (Field Emission Displays) or SEDs (Surface-Conduction Electron-Emitter Displays)), plasma display panels (PDPs (Plasma Display Panels)), cathode ray tubes (CRTs (Cathode-Ray Tubes)), liquid crystal display backlights, and white light-emitting diodes (LEDs (Light-Emitting Diodes)). In any of these applications, it is necessary to supply energy to the phosphor to excite it in order to make it emit light. Phosphors are excited by a high-energy excitation source such as vacuum ultraviolet light, ultraviolet light, an electron beam, or blue light, and emit visible light such as blue light, green light, yellow light, orange light, or red light.

Many phosphors have been reported to date (see, for example, Patent Documents 1 to 6). Patent Document 1 discloses an orange-emitting sialon phosphor containing an alkaline earth element. As another example, Patent Document 2 discloses a green phosphor in which β-sialon is activated with Eu ²⁺ . Patent Document 3 discloses that in this phosphor, the emission wavelength shifts to a shorter wavelength by changing the oxygen content while maintaining the crystal structure. Furthermore, as an example of an oxynitride phosphor, Patent Document 4 discloses a blue phosphor in which a JEM phase (LaAl(Si _6-z Al _z )N _10-z O _z ) host crystal is activated with Ce. In this phosphor, it is known that by substituting a portion of La with Ca while maintaining the crystal structure, the excitation wavelength and the emission wavelength shift to a longer wavelength. Furthermore, according to Patent Document 5, as another example of an oxynitride phosphor, a blue phosphor is known in which La-N crystal La ₃ Si ₈ N ₁₁ O ₄ is used as a host crystal and activated with Ce.

Na ₅ Al ₃ F ₁₄ is a crystal known as chiolite, and according to Patent Document 6, phosphors doped with Mn ⁴⁺ are known as red phosphors. Chiolite itself is almost colorless and transparent, and is said to be snow-white. It has a glassy luster and a specific gravity of 2.998.

In this way, the emitted color of a phosphor is determined by the combination of the host crystal and the metal ions (activator ions) dissolved in it. Furthermore, the combination of host crystal and activator ions determines the luminescence characteristics such as the emission spectrum and excitation spectrum, as well as chemical and thermal stability, so if the host crystal or activator ions are different, they are considered to be different phosphors. Furthermore, materials with the same chemical composition but different crystal structures are considered to be different phosphors, as the luminescence characteristics and stability differ due to the different host crystals.

Japanese Patent Application Laid-Open No. 2002-363554 Japanese Patent Application Laid-Open No. 2005-255895 International Publication No. 2007/066733 International Publication No. 2005/019376 Japanese Patent Application Laid-Open No. 2005-112922 Japanese Patent Application Laid-Open No. 2019-215451

In embodiments of the present invention, a novel phosphor with specific emission characteristics can be provided. It can have emission characteristics (emission color, excitation characteristics, emission spectrum) that differ from those of conventional phosphors. In particular, an inorganic phosphor that emits light in the purple region from 380 nm to 410 nm and has an emission spectrum with a half-width of 40 nm or less, and a method for manufacturing the same, can be provided. In embodiments of the present invention, a light-emitting device with excellent durability using such a phosphor can be provided.

Under these circumstances, the present inventors conducted detailed research on _phosphors based on fluorine- _containing crystals and found that inorganic materials using _Na5Al3F14 crystal (hereinafter referred to as the present crystal) and a crystal having the same crystal structure as _Na5Al3F14 crystal (hereinafter referred to as the present identical crystal) as a host crystal and doped with _Eu emit high-intensity fluorescence. _They also found that certain compositions exhibit purple light emission. Furthermore, they found that the use of this phosphor allows the production of colored or white light-emitting diode devices containing spectral components with narrow half-widths, as well as lighting fixtures and image display devices using such devices.

In an embodiment of the present invention, the phosphor comprises an inorganic compound containing at least sodium (Na), aluminum (Al), _fluorine (F), and europium (Eu), and the _inorganic compound may contain at least Eu in a _Na5Al3F14 crystal or a crystal having the same crystal structure _{as Na5Al3F14 .}
The phosphor may also be a phosphor containing an inorganic compound containing at least sodium (Na), aluminum (Al), fluorine (F), and europium (Eu), the inorganic compound being Na ₅ Al ₃ F ₁₄ crystal containing at least Eu, or a crystal having the same crystal structure as the Na ₅ Al ₃ F ₁₄ crystal.
The inorganic compound may further contain oxygen.
When the ratio of the number of Al atoms to the number of Eu atoms contained in the inorganic compound is expressed as Al:Eu=3:x, the value of x may satisfy the range of 0.0125≦x≦0.1.
The value of x may satisfy the range of 0.025≦x≦0.05.
The inorganic compound may be represented by (Na, Eu, □) ₅ Al ₃ (O, F) ₁₄ (where □ represents an atomic deficiency).
The inorganic compound may further contain magnesium (Mg), and may have a composition represented by (Na,Eu) ₅ (Al,Mg) ₃ F ₁₄ .
The inorganic compound may have a composition of Na _5-x Eu _x Al ₃ F _14+x (where 0.025≦x≦0.05).
The inorganic compound may have a composition of Na _5-2x Eu _x Al ₃ F ₁₄ (where 0.025≦x≦0.05).
Any of the above phosphors may emit fluorescence having a peak in the wavelength range of 380 nm or more and 410 nm or less when irradiated with light in the wavelength range of 250 nm or more and less than 380 nm.
Any of the above phosphors may emit fluorescence having a spectral shape with a half width of 20 nm to 40 nm when irradiated with light in a wavelength range of 250 nm to less than 380 nm.
In an embodiment of the present invention, any of the above-described methods for manufacturing a phosphor may include mixing raw materials containing at least sodium fluoride, europium fluoride, and aluminum fluoride, and reacting the raw materials at a temperature in the range of 500°C to 1200°C.
In an embodiment of the present invention, the light-emitting device includes at least a luminescent source and a phosphor, the luminescent source emitting light in a wavelength range of 250 nm or more and less than 380 nm, and the phosphor may include any of the above phosphors.
In any of the above light-emitting devices, the phosphor may further include a blue phosphor having a peak emission wavelength in the range of 440 nm or more and 500 nm or less, a green phosphor having a peak emission wavelength in the range of 500 nm or more and 580 nm or less, and a red phosphor having a peak emission wavelength in the range of 600 nm or more and 700 nm or less.

In an embodiment of the present invention, the phosphor may contain this crystal or the same crystal as the present crystal as a main component. It exhibits higher luminescence brightness than conventional oxide phosphors and oxynitride phosphors, and in certain compositions is excellent as a purple phosphor. It may also be characterized by a narrow half-width of the emission spectrum. Even when exposed to an excitation source, this phosphor is resistant to a decrease in luminance, providing a useful phosphor that can be suitably used in light-emitting devices such as white light-emitting diodes, lighting fixtures, backlight sources for liquid crystal displays, infrared emitting lighting, infrared light sources for inspection, etc.

1 shows a schematic diagram of the crystal structure of Na ₅ Al ₃ F ₁₄ crystal. 1 shows a schematic diagram of the powder X-ray pattern (CuKα ₁ ) of Example 3. 1 shows a schematic diagram of the powder X-ray pattern (CuKα ₁ ) of Example 7. FIG. 1 shows the excitation and emission spectra of the product of Example 1. FIG. 10 is a schematic diagram showing a lighting fixture (bullet-shaped LED lighting fixture) according to Example 9. FIG. 10 is a schematic diagram showing a lighting fixture (board-mounted LED lighting fixture) according to Example 10.

The present invention will be explained in detail below in the examples.
In an embodiment of the present invention, the phosphor contains an inorganic compound containing at least sodium (Na), aluminum (Al), fluorine (F), and europium (Eu ₎ . Such an inorganic compound contains at least _Eu in a _Na5Al3F14 crystal (the present crystal) or a crystal having the same crystal structure as _Na5Al3F14 (the present _crystal ) _. Specifically, the inorganic compound uses the present crystal or the present crystal as a host crystal, and Eu2 ⁺ is contained in the host crystal. The inventors have discovered that a combination of the present crystal or the present crystal with Eu2 ⁺ results in a phosphor that emits purple fluorescence due to the influence of a crystal field. To the best of the inventors' knowledge, the combination of the present crystal or the present crystal with Eu2 ⁺ is a phosphor combination that has not been reported prior to the filing of the present application.

As mentioned above, _{the Na5Al3F14} crystal is known as thiolite. Chiolite is a substance that belongs to the _tetragonal crystal system, the P4/mnc space group (number 128 in the International Tables for Crystallography), and is characterized by lattice constants (a = 7.014 Å, b = 7.014 Å, c = 10.402 Å). In an embodiment of the present invention, this crystal (see, for example, FIG. 1 ) and this identical crystal can be identified by X-ray diffraction or neutron diffraction. This identical crystal is a crystal in which the lattice constants and atomic positions have changed due to the substitution of constituent elements with other elements in _{the Na5Al3F14} crystal _. However, the crystal structure, the sites occupied by the atoms, and the atomic positions given by their coordinates do not change so significantly that the chemical bonds between the framework atoms are broken.

In this specification, when the ten major diffraction peaks (2θ) with the strongest diffraction intensity among the X-ray diffraction results measured for the target substance match the diffraction data obtained from calculations (ICDD04-010-1794), the target substance is identified as this crystal or this identical crystal.

The inorganic compound may contain oxygen (O). In this case, the present crystal or the present identical crystal further contains oxygen (O), and part of the F in the crystal is substituted with oxygen, which makes it easier to maintain charge neutral when Na in the crystal is substituted with Eu ²⁺ , thereby stabilizing the crystal and increasing the luminescence intensity.

The concentration of Eu ²⁺ added to the crystal affects the luminescence characteristics. When the ratio of the number of Al and Eu atoms contained in the inorganic compound is expressed as Al:Eu = 3:x, a phosphor with an Eu content (x) of 0.0125≦x≦0.1 has high luminescence intensity. If it is less than 0.0125, the amount of Eu is too small, which may result in a decrease in luminescence intensity. Furthermore, if it exceeds 0.1, the distance between Eu atoms contained in the crystal becomes short, which may lead to energy dissipation due to concentration quenching, resulting in a decrease in luminescence intensity. More preferably, x satisfies the range of 0.025≦x≦0.05. This increases the luminescence intensity.

The inorganic compound is preferably represented by (Na, Eu, □) ₅ Al ₃ (O, F) ₁₄ (where □ represents an atomic deficiency). In the examples of the present invention, Na and Eu are always included. Phosphors containing such inorganic compounds tend to maintain charge neutrality, stabilizing the crystal structure and increasing the luminescence intensity. When Eu is added to Na ₅ Al ₃ F ₁₄ crystals, Eu tends to occupy the Na site in the crystal. Since Na tends to be monovalent and Eu tends to be divalent, a composition in which two Na atoms are substituted with one Eu atom can be selected to match the overall charge. Alternatively, the charges can be matched by substituting one Eu atom for one Na atom and simultaneously substituting one F atom for one oxygen atom.

The inorganic compound may further contain magnesium (Mg) and be represented by (Na _, Eu) ₅ (Al,Mg) _3F14 . Here, in the embodiments of the present invention, Na and Eu are always included (0<Na<5 and 0<Eu<5). Phosphors containing such inorganic compounds tend to maintain charge neutrality, stabilizing the crystal structure and increasing the luminescence intensity. When Eu and Mg are added to _Na5Al3F14 crystal, Eu tends to occupy the Na site in the crystal, and Mg tends to occupy the Al site in the crystal. _Na tends to be monovalent, _Eu tends to be divalent, Al tends to be trivalent, and Mg tends to be divalent. By substituting one Na atom with one Eu atom and simultaneously substituting one Al atom with one Mg, the charges can be matched.

The inorganic compound is preferably represented by Na _5-x Eu _x Al ₃ F _14+x (where 0.025≦x≦0.05). Phosphors containing such inorganic compounds tend to maintain charge neutrality, stabilizing the crystal structure and increasing the luminescence intensity. When Eu is added to Na ₅ Al ₃ F ₁₄ crystals, Eu tends to occupy the Na site in the crystal. Na tends to be monovalent, while Eu tends to be divalent. By substituting one Na atom with one Eu atom and simultaneously inserting one F atom between the crystal lattices, the charges can be combined.

The inorganic compound preferably has a composition of Na _5-2x Eu _x Al ₃ F ₁₄ (where 0.025≦x≦0.05). Phosphors containing such inorganic compounds tend to maintain charge neutrality, stabilizing the crystal structure and increasing luminescence intensity. In this case, two Na atoms in the Na ₅ Al ₃ F ₁₄ crystal are replaced with one Eu atom, leaving one atomic deficiency at the Na position, maintaining charge neutrality. If the value of x is less than 0.025, the amount of Eu responsible for luminescence is small, which may result in low luminescence intensity. If the value of x is greater than 0.05, the luminescence intensity may be low due to concentration quenching. For example, in FIG. 1, Eu may occupy some of the Na sites. Furthermore, O may occupy some of the F sites.

In an embodiment of the present invention, the phosphor has a specific composition, which allows it to have a peak (maximum value of the peak) in the wavelength range of 380 nm or more and 410 nm or less when irradiated with light in the wavelength range of 250 nm or more and less than 380 nm. In an embodiment of the present invention, the phosphor more preferably has a peak in the wavelength range of 385 nm or more and 400 nm or less when irradiated with light in the wavelength range of 250 nm or more and less than 380 nm. A typical peak is 393 nm. This allows for a spectrum suitable for purple light emission applications.

In addition, in an embodiment of the present invention, the phosphor has a specific composition, and thereby preferably emits fluorescence with a spectral shape having a half-width in the range of 20 nm to 40 nm. In an embodiment of the present invention, the phosphor more preferably emits fluorescence with a spectral shape having a half-width in the range of 25 nm to 35 nm.

In this embodiment of the present invention, the method for producing the phosphor does not need to be particularly specified, but it can be obtained, for example, by mixing raw materials containing sodium fluoride, europium fluoride, and aluminum fluoride and firing them at a temperature in the range of 500°C to 1200°C. If the temperature is lower than 500°C, the reaction may not proceed sufficiently. If the temperature exceeds 1200°C, the raw material powder and the compound may decompose. The firing atmosphere may be air, nitrogen, nitrogen-hydrogen, argon, etc. The firing time varies depending on the firing temperature, but is usually preferably around 1 hour to 96 hours.

The average particle size of the phosphor powder is preferably 50 nm or more and 200 μm or less in volumetric median diameter (d50), as this results in high luminescence intensity. The volumetric average particle size can be measured, for example, using a microtrack or laser scattering method. The average particle size of the phosphor powder synthesized by firing can be adjusted to 50 nm or more and 200 μm or less by using one or more methods selected from pulverization, classification, and acid treatment.

When firing to synthesize phosphors, adding an inorganic substance that forms a liquid phase at temperatures below the firing temperature can act as a flux, promoting reaction and grain growth and resulting in stable crystals, which can improve luminescence intensity.

Furthermore, washing with a solvent after firing can reduce the content of inorganic substances that form a liquid phase at temperatures below the firing temperature, which can increase the luminescence intensity of the phosphor.

In the embodiments of the present invention, when a phosphor is used in applications such as a light-emitting device, it is preferable to use it in a form in which it is dispersed in a liquid medium. In the embodiments of the present invention, it may also be used as a phosphor mixture containing a phosphor. In the embodiments of the present invention, a phosphor dispersed in a medium is referred to as a phosphor-containing composition.

In the embodiments of the present invention, any medium that can be used in the phosphor-containing composition can be selected depending on the purpose, etc., as long as it can suitably disperse the phosphor as in the embodiments of the present invention and does not cause undesirable reactions, etc. Examples of media include glass, silicone resin, epoxy resin, polyvinyl resin, polyethylene resin, polypropylene resin, polyester resin, etc. These media may be used alone, or two or more may be used in any combination and ratio.

In embodiments of the present invention, a light-emitting device can be constructed by combining a phosphor with a light source (excitation source). Light sources include light-emitting diodes (LEDs), laser diodes (LDs), organic electroluminescent (EL) elements, and fluorescent lamps. In embodiments of the present invention, LEDs can be manufactured using phosphors by known methods such as those described in Japanese Patent Application Laid-Open Nos. 5-152609, 7-99345, and Japanese Patent Publication No. 2927279. In this case, the light emitter or light source used emits light in the wavelength range of 250 nm or more and less than 380 nm. These LEDs include those made of semiconductors such as GaN, InGaN, and AlN, and by adjusting their composition, they can become light sources that emit light of a specified wavelength.

In an embodiment of the present invention, as one form of light-emitting device, in addition to the phosphors in the embodiments of the present invention, a blue phosphor having a peak emission wavelength in the range of 440 nm to 500 nm, a green phosphor having a peak emission wavelength in the range of 500 nm to 580 nm, and a red phosphor having a peak emission wavelength in the range of 600 nm to 700 nm can be included. This allows the embodiment of the present invention to produce a light-emitting device that contains blue, green, and red color components in addition to the light emitted from the phosphors (purple).

In an embodiment of the present invention, as one form of light-emitting device, in addition to the phosphors in the embodiments of the present invention, a blue phosphor having a peak emission wavelength in the range of greater than 410 nm and less than 500 nm, a green phosphor having a peak emission wavelength in the range of greater than 500 nm and less than 580 nm, and an orange to red phosphor having a peak emission wavelength in the range of greater than 580 nm and less than 700 nm can be included. This allows the embodiment of the present invention to produce a light-emitting device that contains blue, green, and orange to red color components in addition to the light emitted from the phosphor (purple).

Examples of such blue phosphors include AlN:(Eu, _Si ), _BaMgAl10O17 : _{Eu , SrSi9Al19ON31 :} Eu, _{LaSi9Al19N32 :} Eu, α-sialon:Ce, and JEM:Ce.

Examples of such green phosphors include β-sialon:Eu, (Ba, Sr, Ca, Mg) ₂ SiO ₄ :Eu, and (Ca, Sr, Ba)Si ₂ O ₂ N ₂ :Eu.

Such red phosphors include _CaAlSiN3 :Eu, (Ca, _Sr ) _AlSiN3 : _Eu , _Ca2Si5N8 :Eu, _{and Sr2Si5N8 :} Eu.

The present invention will be explained in more detail using the specific examples shown below. These examples are provided solely as an aid to facilitate understanding of the present invention. The present invention is not limited to these examples.

[Raw materials used in synthesis]
The raw material powders used in the synthesis were sodium fluoride (manufactured by Sigma-Aldrich Japan G.K., model number 201154), europium fluoride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number 053-05171), europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd., model number EU-03-129), aluminum fluoride (manufactured by Kojundo Chemical Laboratory Co., Ltd., model number ALH17PB), aluminum oxide (manufactured by Taimei Chemical Industry Co., Ltd., model number TM-DAR), and magnesium fluoride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., model number 137-09101).

[Phosphor Examples: Examples 1 to 8]
In Examples 1 to 8, raw material powders were mixed so that the ratio of metal atoms satisfied the composition shown in Table 1, and phosphors were synthesized.

Specifically, in Examples 1 to 4, sodium fluoride powder, europium fluoride powder, and aluminum fluoride powder were weighed and mixed in air so that the ratio Na:Eu:Al = 5-2x:x:3 (x = 0.05, 0.0125, 0.025, 0.1), respectively. The mixed powder was loaded onto an alumina boat and fired at 700°C for 4 hours in a mixed gas stream containing 5% by volume of hydrogen gas and the remainder being nitrogen.

In Example 5, the synthesis was carried out in the same manner as in Examples 1 to 4, except that sodium fluoride powder, aluminum fluoride powder, and europium oxide powder were weighed out so that the ratio of Na:Eu:Al was 4.975:0.025:3.

In Example 6, the synthesis was carried out in the same manner as in Examples 1 to 4, except that sodium fluoride powder, europium fluoride powder, aluminum fluoride powder, and aluminum oxide powder were weighed out so that the ratio of Na:Eu:Al was 4.975:0.025:3.

Here, aluminum oxide was used to offset the excess positive charge (0.025) generated by Eu doping. The amounts of aluminum fluoride powder and aluminum oxide powder were set as follows: 0.01667 (≒0.025/1.5) of Al (calculated as AlO1.5) in aluminum oxide (Al ₂ O ₃ ), and 2.98333 (=3-0.01667) of aluminum fluoride (AlF ₃ ) as the remaining Al component, for a total Al amount of 3.

In Example 7, the synthesis was carried out in the same manner as in Examples 1 to 4, except that sodium fluoride powder, europium fluoride powder, aluminum fluoride powder, and magnesium fluoride powder were weighed out so that the ratio of Na:Eu:Al:Mg was 4.975:0.025:2.975:0.025.

In Example 8, the synthesis was carried out in the same manner as in Examples 1 to 4, except that sodium fluoride powder, europium fluoride powder, and aluminum fluoride powder were weighed out so that the ratio of Na:Eu:Al was 4.975:0.025:3.

The product phases of the products of Examples 1 to 8 were identified using powder X-ray diffraction. The results are shown in Table 2. The emission spectra of the products of Examples 1 to 8 were measured using a spectrofluorometer (FP8600, manufactured by JASCO Corporation). The results are shown in FIG. 4 and Table 3.
The above results will be summarized.

The powder X-ray diffraction patterns of the products of Examples 1 to 8 were in good agreement with the crystal pattern of Na ₅ Al ₃ F ₁₄ crystal (ICDD04-010-1794). For example, the powder X-ray diffraction patterns of Examples 3 and 7 are shown in FIGS. 2 and 3, respectively. From this, it was found that the product phases of the products of Examples 1 to 8 had the same crystal structure as Na ₅ Al ₃ F ₁₄ crystal or Na ₅ Al ₃ F ₁₄ crystal, as shown in Table 2. Here, a host crystal consisting of Na, Al, F, and Eu is considered to be Na ₅ Al ₃ F ₁₄ crystal, and a host crystal consisting of Na, Al, F, Eu, and other elements is considered to be a crystal having the same crystal structure as Na ₅ Al ₃ F ₁₄ crystal. However, in Examples 1 to 4, it is believed that the inclusion of Eu makes some of the Na sites vacant. On the other hand, in Examples 5 to 7, in addition to Na, Al, F, and Eu, O and/or Mg are thought to be present to constitute the host crystal. For example, the X-ray diffraction patterns of Examples 3 and 7 appear almost identical, but the elements contained in Example 3 are limited to Na, Al, F, and Eu, while Example 7 further contains O and/or Mg. Furthermore, in Example 8, the inclusion of Eu is thought to cause some F to penetrate between lattices, and the F that has penetrated between lattices is treated as the same crystal structure. When F exceeds 14, charge neutrality is maintained. In this way, Na ₅ Al ₃ F ₁₄ crystals can be distinguished from crystal structures identical to Na ₅ Al ₃ F ₁₄ crystals. It was confirmed that the compositions of the products of Examples 1 to 8 matched the design compositions shown in Table 1. Specifically, Example 1 was _{Na4.9Eu0.05Al3F14} , _{Example 2 was Na4.975Eu0.0125Al3F14} , _{Example 3} was _{Na4.95Eu0.025Al3F14 , Example 4 was Na4.8Eu0.1Al3F14 , and Example 8 was Na4.975Eu0.025Al3F14.025 .}

Figure 4 shows the excitation spectrum and emission spectrum of the product of Example 1.

Figure 4 shows that the product of Example 1 is efficiently excited by light having a wavelength range of 250 nm or more and less than 380 nm, emits near-ultraviolet light with a peak at 393 nm, and functions as a phosphor. It was also confirmed that the phosphor of Example 1 emits fluorescence with a spectral shape having a half-width of 20 nm or more and 40 nm or less.

Furthermore, the emission peak wavelength, emission intensity, and half-width of the peak wavelength were determined from the excitation and emission spectra. The results are shown in Table 3. The excitation wavelength used for the measurements was the wavelength with the highest emission intensity in the excitation spectrum. In Table 3, the emission intensities of the phosphors in Examples 2 to 8 are relative intensities to the emission intensity of the phosphor in Example 1.

It was found that the phosphors of Examples 1 to 4 in Table 3, regardless of the amount of Eu added, were all excited by light having a peak in the wavelength range of 250 nm or more and less than 380 nm, and emitted near-ultraviolet light having a peak in the wavelength range of 380 nm or more and 410 nm or less.

Furthermore, according to Table 3, the emission intensity increases as the amount of Eu added increases, and it was found that the emission intensity can be increased preferably when the amount of Eu added x is 0.0125 or more and 0.1 or less (0.25 atomic % or more and 2 atomic % or less relative to Na), and more preferably when the amount of Eu added x is 0.025 or more and 0.05 or less (0.5 atomic % or more and 1 atomic % or less relative to Na).

Furthermore, according to Table 3, the phosphors of Examples 6 to 8 are also excited by light having a peak in the wavelength range of 250 nm or more and less than 380 nm, and emit near-ultraviolet light having a peak in the wavelength range of 380 nm or more and 410 nm or less. It was also found that crystals having the same crystal structure as Na ₅ Al ₃ F ₁₄ crystals in which oxygen and magnesium are solid-solved are also effective as host crystals.

[Light-emitting device: Example 9]
FIG. 5 is a schematic diagram showing a lighting fixture (bullet-type LED lighting fixture) according to Example 9.

A bullet-shaped white light-emitting diode lamp (1) as shown in Figure 5 was fabricated. It has two lead wires (2, 3), one of which (2) has a recess and is fitted with an ultraviolet light-emitting diode element (4) with an emission peak at 300 nm. The lower electrode of the ultraviolet light-emitting diode element (4) is electrically connected to the bottom of the recess with conductive paste, and the upper electrode is electrically connected to the other lead wire (3) with a thin gold wire (5). Phosphor (7) is dispersed in resin and mounted near the light-emitting diode element (4). This first resin (6) with dispersed phosphor is transparent and covers the entire light-emitting diode element (4). The tip of the lead wire, including the recess, the light-emitting diode element, and the first resin with dispersed phosphor are sealed with a transparent second resin (8). The transparent second resin (8) is generally cylindrical, with its tip curved like a lens, which is commonly referred to as a bullet-shaped lamp.

In this example, the phosphor powder prepared in Example 1 was mixed with epoxy resin at a concentration of 35% by weight, and an appropriate amount of this was dropped using a dispenser to form a first resin (6) with the phosphor mixture (7) dispersed therein. The color of the resulting light-emitting device contained a purple luminescent component.

[Light-emitting device: Example 10]
FIG. 6 is a schematic diagram showing a lighting fixture (board-mounted LED lighting fixture) according to Example 10.

A chip-type light-emitting diode lamp (11) for substrate mounting, as shown in Figure 6, was fabricated. Two lead wires (12, 13) were fixed to a white alumina ceramic substrate (19) with high visible light reflectance. One end of each wire was located approximately in the center of the substrate, while the other end extended to the outside, forming an electrode to be soldered when mounted on an electrical substrate. An ultraviolet light-emitting diode element (14) with an emission peak wavelength of 320 nm was mounted and fixed to one end of one of the lead wires (12) so that it was in the center of the substrate. The lower electrode of the ultraviolet light-emitting diode element (14) was electrically connected to the lower lead wire with conductive paste, and the upper electrode was electrically connected to the other lead wire (13) with a thin gold wire (15).

A mixture of a first resin (16) and a phosphor powder ( ₁₇ ) prepared by mixing the phosphor prepared in Example 1, JEM:Ce blue phosphor, β-sialon:Eu, and CaAlSiN3:Eu in a mass ratio of 4:4:1:1 is mounted near the light-emitting diode element. The first resin with the dispersed phosphor is transparent and covers the entire light-emitting diode element (14). A wall member (20) having a central hole is fixed to the ceramic substrate. The wall member (20) has a central hole for receiving the light-emitting diode element (14) and the resin (16) with the dispersed phosphor (17), and the portion facing the center is sloped. This slope is a reflective surface for extracting light forward, and the curved shape of the slope is determined taking into account the direction of light reflection. At least the surface constituting the reflective surface is a white or metallic luster surface with high visible light reflectance. In this example, the wall member (20) was made of white silicone resin. The hole in the center of the wall member forms a recess in the final shape of the chip-type light-emitting diode lamp, and this recess is filled with a transparent second resin (18) so as to completely seal the light-emitting diode element (14) and the first resin (16) in which the phosphor (17) is dispersed. In this example, the same epoxy resin was used for the first resin (16) and the second resin (18). A white LED device containing a wide range of light components from 380 nm to 700 nm was obtained.

In embodiments of the present invention, the phosphor may have emission characteristics (emission color, excitation characteristics, emission spectrum) that differ from conventional phosphors. Even when combined with an LED excitation source, it can have high emission intensity and be chemically and thermally stable. Furthermore, since the phosphor's brightness decreases little when exposed to an excitation source, it is a phosphor that can be suitably used in colored or white LEDs, etc. It is expected that this phosphor will be widely used in the material design of various display devices in the future, contributing to industrial development.

REFERENCE SIGNS LIST 1 bullet-type light-emitting diode lamp 2, 3 lead wire 4 light-emitting diode element 5 gold thin wire 6, 8 resin 7 phosphor 11 chip-type white light-emitting diode lamp for substrate mounting 12, 13 lead wire 14 light-emitting diode element 15 bonding wire 16, 18 resin 17 phosphor 19 alumina ceramic substrate 20 side member

Claims (6)

Contains an inorganic compound containing at least sodium (Na), aluminum (Al), fluorine (F), and europium (Eu),
the inorganic compound includes Na ₅ Al ₃ F ₁₄ crystals containing at least Eu;
The inorganic compound is a phosphor having a composition of Na _5-2x Eu _x Al ₃ F ₁₄ (where 0.025≦x≦0.05). The phosphor described in claim 1, which emits fluorescence having a peak in the wavelength range of 380 nm to 410 nm when irradiated with light in the wavelength range of 250 nm to less than 380 nm. 2. The phosphor according to claim 1, which emits fluorescence having a spectral shape with a half- width of 20 nm to 40 nm when irradiated with light having a wavelength in the range of 250 nm to less than 380 nm. 4. The method for producing a phosphor according to claim 1 , comprising mixing raw materials containing at least sodium fluoride, europium fluoride, and aluminum fluoride, and reacting the mixture at a temperature in the range of 500°C to 1200°C. A light-emitting device comprising at least a light-emitting source and a phosphor,
the light emitting source emits light in a wavelength range of 250 nm or more and less than 380 nm,
A light-emitting device, wherein the phosphor comprises the phosphor according to any one of claims 1 to 3 . 6. The light-emitting device according to claim 5, wherein the phosphor further comprises a blue phosphor having a peak emission wavelength in the range of 440 nm to 500 nm, a green phosphor having a peak emission wavelength in the range of 500 nm to 580 nm, and a red phosphor having a peak emission wavelength in the range of 600 nm to 700 nm.