JP6763387B2 - Fluorescent material, its manufacturing method, and light emitting device - Google Patents

Description

The present invention relates to a fluorescent substance and a method for producing the same and a light emitting device, and more particularly to a fluorescent substance exhibiting green light emission and a method for producing the same and a light emitting device.

Conventionally, a white light emitting diode (white LED) is widely used as a two-color mixed type in which a semiconductor light emitting element that emits blue light and a yellow phosphor are combined to obtain white light by mixing blue and yellow. ing. However, the white light emitted by this two-color mixed type white LED has a problem of poor color rendering properties. Therefore, as another configuration, a semiconductor light emitting element that emits blue light and two types of phosphors, green and red, are combined, and the light from the semiconductor light emitting element excites each phosphor to produce blue. , A three-color mixed type white LED that obtains white light by mixing green and red is being developed.

As a phosphor that emits green light, green phosphors having various compositions have been developed. For example, Patent Document 1 and Non-Patent Document 1, as the green phosphor used for the LED or the _{like, Sr 5-y-z-} a M y Si 23-x Al 3 + x O x + 2a N 37-x-2a: Eu z A fluorescent substance having a _Cez1 composition is described, and in particular, an example of Patent Document 1 describes a fluorescent substance having an Sr _4.9 Al ₅ Si ₂₁ O ₂ N ₃₅ : Eu _0.1 composition.

Further, for example, Patent Document 2 includes a crystal of the Sr ₃ Si ₁₃ Al ₃ O ₂ N ₂₁ genus activated with Eu, which defines the ratio of the oxygen concentration in the outer region to the oxygen concentration in the inner region in the crystal. Described are phosphors that contain particles and exhibit emission with emission peaks between wavelengths of 490-580 nm when excited by light with a wavelength of 250-500 nm.

Japanese Patent Publication No. 2011-505451 Japanese Unexamined Patent Publication No. 2013-43937

Chemistry-A European Journal 2009, 15, 5311-5319

However, the green phosphors described in Patent Document 1 and Non-Patent Document 1 have a problem that the emission characteristics are not sufficient and the emission intensity is particularly low. Further, as described in Non-Patent Document 1, orange to red phosphors such as SrAlSi ₄ N ₇ and Sr ₂ Si ₅ N ₈ are generated as heterogeneous phases, and therefore need to be mechanically removed. Have a problem. Further, although the phosphor described in Patent Document 2 has high stability of emission intensity with respect to heat, further improvement is expected in the emission characteristics of the phosphor itself.

Further, it is known that if the particle size of the white LED phosphor is too large, it becomes difficult to uniformly disperse it in the resin and the color tone varies, and it is necessary to control it within a predetermined particle size range. Further, if pulverization and classification are performed in order to reduce the particle size, fine particles are generated and cause a decrease in brightness. Therefore, it is necessary to control the particle size to a predetermined size without requiring a pulverization step.

The present invention has been made in view of the above problems, and is a phosphor having a predetermined particle size, suppressing the formation of different phases, and having superior emission characteristics, particularly emission intensity, and production thereof. It is an object of the present invention to provide a method as well as a light emitting device.

In order to achieve the above object, the present inventors have conducted diligent research, and as a result, a green phosphor activated with europium and / or cerium contains a specific amount of boron to obtain a predetermined particle size. It was found that the generation of different phases can be suppressed and the emission intensity can be significantly improved, and the present invention has been made.

That is, the present invention relates to a fluorescent substance containing a crystal phase represented by the composition of the following formula (1), further containing 100 to 2500 ppm of boron.
_{Sr a M1 b Al c Si d} N e O f: Eu x1 Ce y1 ··· (1)
(Here, M1 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, 2 ≦ a ≦ 8, 0 ≦ b ≦ 3, 2 ≦ c ≦ 7, 10 ≦ d ≦ 25, 15 ≦ e ≦ 37, 0 ≦ f ≦ 3, 0 <x1 + y1 ≦ 0.6)

Further, the present invention is a phosphor having a crystal phase having at least an Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure, and is a phosphor having a Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure in an X-ray diffraction pattern. 021) When the diffraction peak intensity derived from the plane is A and the diffraction peak intensity derived from the (221) plane of the phosphor having the SrAlSi ₄ N ₇ structure is B, B / A <0.03. Regarding the characteristic phosphor.

The present invention also relates to a phosphor containing a crystal phase represented by the composition of the following formula (2).
_{Sr g M2 h B i Al j} Si k N l O m: Eu x2 Ce y2 ··· (2)
(Here, M2 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, and 2 ≦ g ≦ 8, 0 ≦ h ≦ 3, 0.02 ≦ i ≦ 0.8, 2 ≦ j ≦ 7, 10 ≦ k ≦ 25, 15 ≦ l ≦ 37, 0 ≦ m ≦ 3, 0 <x2 + y2 ≦ 0.6)

Further, the present invention comprises a step of mixing an Sr-containing compound, an Al-containing compound, a Si-containing compound, an Eu-containing compound and / or a Ce-containing compound, and a B-containing compound to obtain a raw material mixture, and the raw material mixture is an inert gas. A method for producing a phosphor, which comprises a step of firing in an atmosphere or a reducing gas atmosphere, wherein the amount of the B-containing compound added is 250 to 10,000 ppm of the raw material mixture. Regarding the manufacturing method of.

Further, the present invention relates to a light emitting device including the above-mentioned phosphor and a light source that irradiates the phosphor with excitation light to emit light.

According to the present invention, it is possible to provide a phosphor, a method for producing the same, and a light emitting device, which are controlled to a predetermined particle size, suppress the formation of different phases, and have more excellent light emitting characteristics, particularly light emitting intensity than conventional ones. ..

It is a figure which shows the X-ray diffraction (XRD) pattern of the phosphor obtained in Example 5 and Comparative Example 1. FIG. It is a figure which shows the emission spectrum of the phosphor obtained in Example 5 and Comparative Example 1. 6 is a scanning electron micrograph of the phosphors obtained in Example 5 and Comparative Example 1. It is a figure which shows the B concentration depth profile of the phosphor obtained in Example 5.

1. 1. Fluorescent material The fluorescent material of the present invention contains a crystal phase represented by the composition of the following formula (1).
_{Sr a M1 b Al c Si d} N e O f: Eu x1 Ce y1 ··· (1)
(Here, M1 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, 2 ≦ a ≦ 8, 0 ≦ b ≦ 3, 2 ≦ c ≦ 7, 10 ≦ d ≦ 25, 15 ≦ e ≦ 37, 0 ≦ f ≦ 3, 0 <x1 + y1 ≦ 0.6)

That is, the fluorescent substance of the present invention is a fluorescent substance activated by europium (Eu) and / or cerium (Ce), and when excited by light having a wavelength of 330 to 500 nm, it peaks between 500 and 560 nm. It is a green fluorescent substance having.

In the phosphor of the present invention, europium (Eu) and / or cerium (Ce) are activators and have the property of emitting light as luminescent atoms in the phosphor. The molar ratio of europium in the phosphor, that is, the value of x1 is in the range of 0 ≦ x1 ≦ 0.3, preferably in the range of 0.001 ≦ x1 ≦ 0.25, preferably 0.1 ≦ x1 ≦. The range of 0.15 is more preferable. When the value of x1 exceeds 0.3, the luminescent atoms become high in concentration and come close to each other to cancel the luminescence, so that the luminescence intensity tends to be weakened. The molar ratio of cerium in the phosphor, that is, the value of y1 is in the range of 0 ≦ y1 ≦ 0.3, preferably in the range of 0 ≦ y1 ≦ 0.1, and 0 ≦ y1 ≦ 0. The range of 0001 is more preferable. The value of x1 + y1 is in the range of 0 <x1 + y1 ≦ 0.6, preferably in the range of 0.001 ≦ x1 + y1 ≦ 0.25, and more preferably in the range of 0.1 ≦ x1 + y1 ≦ 0.15. The present invention includes the case where the composition does not contain Eu, that is, the case where the value of x1 is 0, or the case where the composition does not contain Ce, that is, the case where the value of y1 is 0, but at least Eu or It needs to have a composition containing any element of Ce, that is, a composition of x1 + y1> 0.

Further, in the phosphor of the present invention, the molar ratio of strontium (Sr) in the phosphor is within the range of 2 ≦ a ≦ 8, preferably within the range of 4 ≦ a ≦ 8, and 4.5 ≦ a ≦. The range of 6 is more preferable, and the range of 4.75 ≦ a ≦ 5.25 is more preferable. When the value of a is within the range of 2 ≦ a ≦ 8, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, M1 is one or more metal elements selected from the group consisting of calcium (Ca), barium (Ba) and magnesium (Mg), and the value of b is 0 ≦ b. The range of ≦ 3 is preferable. In the present invention, the case where the composition does not contain any of Ca, Ba and Mg, that is, the case where the value of b is 0 is also included.

Further, in the phosphor of the present invention, the molar ratio of aluminum (Al) in the phosphor is within the range of 2 ≦ c ≦ 7, preferably within the range of 3 ≦ c ≦ 7, and 4 ≦ c ≦ 6. Within the range is preferred. When the value of c is within the range of 2 ≦ c ≦ 7, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of silicon (Si) in the phosphor is within the range of 10 ≦ d ≦ 25, preferably within the range of 15 ≦ d ≦ 25, and 19.5 ≦ d ≦. The range of 22.5 is more preferable, and the range of 20.5 ≦ d ≦ 21.5 is more preferable. When the value of d is within the range of 10 ≦ d ≦ 25, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of nitrogen (N) in the phosphor is in the range of 15 ≦ e ≦ 37, preferably in the range of 32 ≦ e ≦ 37, and 34 ≦ e ≦ 36. The range is more preferable, and the range of 34.5 ≦ e ≦ 35.5 is more preferable. When the value of e is within the range of 15 ≦ e ≦ 37, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of oxygen (O) in the phosphor is in the range of 0 ≦ f ≦ 3, preferably in the range of 0.1 ≦ f ≦ 2.3. When the value of f is within the range of 0 ≦ f ≦ 3, a high-intensity green phosphor having a narrow half-value width can be obtained.

Here, the phosphor of the present invention is further characterized by containing boron. The content of boron with respect to the entire phosphor is 100 to 2500 ppm, preferably 200 to 1500 ppm, and more preferably 300 to 1500 ppm. If the boron content is less than 100 ppm, the emission intensity does not improve, and if it is more than 2500 ppm, the emission intensity becomes low. The boron content can be measured using an inductively coupled plasma atomic emission spectroscopic analysis (ICP-AES) apparatus.

Further, in the phosphor of the present invention, the element concentration of boron on the outermost surface of the phosphor is preferably 20000 to 100,000 ppm, more preferably 30,000 to 60,000 ppm. In the present invention, the elemental concentration of boron on the outermost surface of the phosphor is defined as the elemental concentration of boron measured at a depth of several nm from the outside, from which photoelectrons can be extracted when the outermost surface of the phosphor is irradiated with X-rays. be able to. The elemental concentration of boron on the outermost surface of the phosphor can be measured using an X-ray photoelectron spectroscopy (XPS) apparatus.

The composition of the phosphor particles is often different between the vicinity of the particle surface and the inside of the particles, and composition fluctuation is confirmed. In the present invention, a depth region of 100 nm (outside to 100 nm) from the outermost surface of the phosphor is defined as the surface of the phosphor, and a depth region beyond the surface of the phosphor (more than 100 nm from the outside) is defined as the inside of the phosphor. be able to. No change in composition is observed inside the phosphor.
In the phosphor of the present invention, it is preferable that the element concentration of boron on the outermost surface of the phosphor is higher than the element concentration of boron inside the phosphor. When the elemental concentration of boron on the outermost surface of the phosphor is higher than the elemental concentration of boron inside the phosphor, a high-intensity green phosphor having a narrow half-value width can be obtained. Specifically, the elemental concentration of boron on the outermost surface of the phosphor preferably has a difference of about 5 to 8 times the elemental concentration of boron existing inside 200 nm from the outermost surface of the phosphor. The elemental concentration of boron existing inside 200 nm from the outermost surface of the phosphor is the number from the surface after etching, which allows photoelectrons to be taken out when the surface after etching is etched from the outermost surface of the phosphor to 200 nm and then the surface after etching is irradiated with X-rays. It can be defined as the elemental concentration of boron measured at a depth of nm and can be measured using an X-ray photoelectron spectroscopy (XPS) device.

Further, the phosphor of the present invention preferably has a half width of the emission spectrum of 70 nm or less. Here, the full width at half maximum is the wavelength width when the emission spectrum is measured when the vertical axis is the emission intensity and the horizontal axis is the wavelength, and when the emission intensity at the peak is I, it becomes I / 2. means. When the half width is relatively narrow as described above, high emission intensity can be obtained.

Further, the phosphor of the present invention determines the diffraction peak intensity derived from the (021) plane of the phosphor having the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure in the X-ray diffraction pattern measured by the X-ray diffraction (XRD) apparatus. When A is defined and the diffraction peak intensity derived from the (221) plane of the phosphor having the SrAlSi ₄ N ₇ structure is B, B / A <0.03 and B / A <0.01. It is preferable that B / A = 0. The Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure is a crystal structure having the same shape as ICSD Coll Code: 420168, and a part of Sr is one or more metals selected from the group consisting of Ca, Ba and Mg. The crystal structure of the phosphor substituted with an element is also included. The SrAlSi ₄ N ₇ structure is a crystal structure having the same shape as ICSD Coll Code: 163667, and a part of Sr is replaced with one or more metal elements selected from the group consisting of Ca, Ba and Mg. The crystal structure of the phosphor is also included. In the present invention, B / A <0.03 means that the amount of crystals having the SrAlSi ₄ N ₇ structure contained as an heterogeneous phase (impurity) in the phosphor of the present invention is small. Since the amount of crystals having the SrAlSi ₄ N ₇ structure is small, a high-intensity green phosphor having a narrow half-value width of the emission spectrum can be obtained.

The phosphor of the present invention is preferably D ₁₀ size measured by a laser diffraction / scattering particle size distribution analyzer is 20 to 30 [mu] m. When the diameter of D ₁₀ is 20 to 30 μm, the number of fine particles is small and the emission intensity is high. When the diameter of D ₁₀ exceeds 30 μm, it becomes difficult to uniformly disperse in the resin when using a light emitting device, specifically, a white light emitting LED, and the color tone tends to vary.

Further, in the phosphor of the present invention, it is preferable that the average value of the Heywood diameter (diameter corresponding to a circle) measured by a scanning electron micrograph is less than 32 μm. For example, the Heywood diameter can be calculated by reading a powder image using the image analysis type particle size distribution measurement software "Mac-View" manufactured by Mountech Co., Ltd. It is preferable that the average value of the Heywood diameter is less than 32 μm because a desired particle size can be obtained without requiring pulverization, particularly when used as a light emitting element of a white LED.

Further, the phosphor of the present invention contains a crystal phase represented by the composition of the following formula (2).
_{Sr g M2 h B i Al j} Si k N l O m: Eu x2 Ce y2 ··· (2)
(Here, M2 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, and 2 ≦ g ≦ 8, 0 ≦ h ≦ 3, 0.02 ≦ i ≦ 0.8, 2 ≦ j ≦ 7, 10 ≦ k ≦ 25, 15 ≦ l ≦ 37, 0 ≦ m ≦ 3, 0 <x2 + y2 ≦ 0.6)

The value of x2 is in the range of 0 ≦ x2 ≦ 0.3, preferably in the range of 0.001 ≦ x2 ≦ 0.25, and more preferably in the range of 0.1 ≦ x2 ≦ 0.15. When the value of x2 exceeds 0.3, the luminescent atoms become high in concentration and come close to each other to cancel the luminescence, so that the luminescence intensity tends to be weakened. The value of y2 is in the range of 0 ≦ y2 ≦ 0.3, preferably in the range of 0 ≦ y2 ≦ 0.1, and more preferably in the range of 0 ≦ y2 ≦ 0.0001. The value of x2 + y2 is in the range of 0 <x2 + y2 ≦ 0.6, preferably in the range of 0.001 ≦ x2 + y2 ≦ 0.25, and more preferably in the range of 0.1 ≦ x2 + y2 ≦ 0.15. The present invention includes the case where the composition does not contain Eu, that is, the case where the value of x2 is 0, or the case where the composition does not contain Ce, that is, the case where the value of y2 is 0, but at least Eu or It needs to have a composition containing any element of Ce, that is, a composition of x2 + y2> 0.

Further, in the phosphor of the present invention, the molar ratio of strontium (Sr) in the phosphor is within the range of 2 ≦ g ≦ 8, preferably within the range of 4 ≦ g ≦ 8, and 4.5 ≦ g ≦. The range of 6 is more preferable, and the range of 4.75 ≦ g ≦ 5.25 is more preferable. When the value of g is within the range of 2 ≦ g ≦ 8, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, M2 is one or more metal elements selected from the group consisting of calcium (Ca), barium (Ba) and magnesium (Mg), and the value of h is 0 ≦ h. The range of ≦ 3 is preferable. In the present invention, the case where the composition does not contain any of Ca, Ba and Mg, that is, the case where the value of h is 0 is also included.

Further, in the phosphor of the present invention, the molar ratio of boron (B) in the phosphor is within the range of 0.02 ≦ i ≦ 0.8 and within the range of 0.04 ≦ i ≦ 0.4. preferable. When the value of i is within the range of 0.04 ≦ i ≦ 0.4, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of aluminum (Al) in the phosphor is within the range of 2 ≦ j ≦ 7, preferably within the range of 3 ≦ j ≦ 7, and 4 ≦ j ≦ 6. Within the range is more preferred. When the value of j is within the range of 2 ≦ j ≦ 7, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of silicon (Si) in the phosphor is within the range of 10 ≦ k ≦ 25, preferably within the range of 15 ≦ k ≦ 25, and 19.5 ≦ k ≦. The range of 22.5 is more preferable, and the range of 20.5 ≦ k ≦ 21.5 is more preferable. When the value of k is within the range of 10 ≦ k ≦ 25, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of nitrogen (N) in the phosphor is in the range of 15 ≦ l ≦ 37, preferably in the range of 32 ≦ l ≦ 37, and 34 ≦ l ≦ 36. The range is more preferable, and the range of 34.5 ≦ l ≦ 35.5 is more preferable. When the value of l is within the range of 15 ≦ l ≦ 37, a high-intensity green phosphor having a narrow half-value width can be obtained.

Further, in the phosphor of the present invention, the molar ratio of oxygen (O) in the phosphor is in the range of 0 ≦ m ≦ 3, preferably in the range of 0.1 ≦ m ≦ 2.3. When the value of m is within the range of 0 ≦ m ≦ 3, a high-intensity green phosphor having a narrow half-value width can be obtained.

2. 2. Method for Producing Fluorescent Substance The phosphor of the present invention contains, for example, an Sr-containing compound, an Al-containing compound, a Si-containing compound, an Eu-containing compound and / or a Ce-containing compound, a B-containing compound, and, if necessary, M. A step of mixing a compound (where M is one or more metal elements selected from the group consisting of Ca, Ba and Mg) to obtain a raw material mixture (mixing step) and the raw material mixture in an inert gas-containing atmosphere. Or, it can be produced by a production method including a step of firing in a reducing gas atmosphere (firing step) and, if necessary, a crushing and classification step.

(1) Mixing step Each raw material-containing compound of Sr-containing compound, Al-containing compound, Si-containing compound, Eu-containing compound, Ce-containing compound, B-containing compound, and M-containing compound is a nitride, an oxynitride, an oxide, or an oxide. It is selected from precursor substances that become oxides by thermal decomposition.

Specific examples of the strontium (Sr) -containing compound are not particularly limited, but for example, one or more kinds selected from the group consisting of strontium nitride (Sr ₃ N ₂ ), strontium carbonate (SrCO ₃ ), and strontium oxide (SrO). Powders can be preferably used, and in particular, strontium nitride (Sr ₃ N ₂ ) powder can be preferably used.

Specific examples of the aluminum (Al) -containing compound are not particularly limited, but are selected from the group consisting of, for example, aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), and aluminum carbonate (Al ₂ (CO ₃ ) ₃ ). One or more kinds of powders can be preferably used, and in particular, aluminum nitride (AlN) powder can be preferably used.

Specific examples of the silicon (Si) -containing compound are not particularly limited, but for example, a group consisting of amorphous silicon nitride (Si ₃ N ₄ ), crystalline silicon nitride (Si ₃ N ₄ ), and silicon dioxide (SiO ₂ ). One or more types of powders selected from the above can be preferably used, and in particular, amorphous silicon nitride (Si ₃ N ₄ ) and crystalline silicon nitride (Si ₃ N ₄ ) powders can be preferably used.

Specific examples of the europium (Eu) -containing compound are not particularly limited, but for example, europium oxide (III) (Eu ₂ O ₃ ), europium oxide (II) (EuO), europium nitride (EuN), and metal europium (Eu). One or more kinds of powders selected from the group consisting of can be preferably used.

Specific examples of the cerium (Ce) -containing compound are not particularly limited, but for example, one or more powders selected from the group consisting of cerium nitride (CeN), cerium oxide (CeO ₂ ), and metallic cerium (Ce) are preferable. Can be used.

Further, the present invention is characterized in that, in addition to the above-mentioned raw material-containing compound, a B-containing compound is added in the range of 250 to 10000 ppm of the raw material mixture. By adding 250 to 10000 ppm of the B-containing compound, it is possible to contain 100 to 2500 ppm of boron in the obtained phosphor. Further, when the B-containing compound is not added, many crystals having an SrAlSi ₄ N ₇ structure are contained as heterogeneous phases (impurities) in the obtained phosphor, but by adding 250 to 10,000 ppm of the B-containing compound, SrAlSi ₄ N ₇ is added. It has been found that the amount of crystals in the structure can be reduced. The amount of the B-containing compound added is preferably 750 to 10000 ppm, more preferably 1000 to 5000 ppm.

Specific examples of the boron (B) -containing compound are not particularly limited, but are selected from the group consisting of, for example, boron nitride (BN), boron oxide (B ₂ O ₃ ), and boron hydroxide (B (OH) ₃ ). One or more powders can be preferably used.

Further, in the present invention, if necessary, an M-containing compound (where M is one or more metal elements selected from the group consisting of Ca, Ba and Mg) can be mixed.

Specific examples of the calcium (Ca) -containing compound in the M-containing compound are not particularly limited, but are selected from the group consisting of, for example, calcium nitride (Ca ₃ N ₂ ), calcium carbonate (CaCO ₃ ), and calcium oxide (CaO). One or more types of powder can be preferably used.

Specific examples of the barium (Ba) -containing compound in the M-containing compound are not particularly limited, but are selected from the group consisting of barium nitride (Ba ₃ N ₂ ), barium carbonate (BaCO ₃ ), and barium oxide (BaO), for example. One or more kinds of powders can be preferably used.

The specific example of the magnesium (Mg) -containing compound in the M-containing compound is not particularly limited, but is selected from the group consisting of magnesium nitride (Mg ₃ N ₂ ), magnesium carbonate (MgCO ₃ ), and magnesium oxide (Mg O), for example. One or more types of powder can be preferably used.

Each of these raw material-containing compounds may be used alone or in combination of two or more. The purity of each raw material-containing compound is preferably 99% by mass or more. Since the mixing ratio of the raw material-containing compound has almost the same composition ratio as that of the formula (1), the mixing ratio is adjusted so as to have a desired composition ratio. However, since the oxygen content and nitrogen content are not always constant, the target oxygen content and nitrogen content can be obtained by setting the mixing ratio of the raw material in consideration of the oxygen content and nitrogen content contained in the raw material. Can be adjusted.

Further, in firing, a Li-containing compound serving as a sintering aid can be added for the purpose of promoting sintering and producing at a lower temperature. Examples of the Li-containing compound used include lithium oxide, lithium carbonate, metallic lithium, and lithium nitride, and each of these powders may be used alone or in combination. The amount of the Li-containing compound added is preferably 0.01 to 0.5 mol as the Li element with respect to 1 mol of the fired product obtained in the firing step described later. The Li-containing compound is easily volatilized in the firing step and is hardly contained in the phosphor powder.

The method for mixing the raw material powder is not particularly limited, and a method known per se, for example, a dry mixing method, a method of wet mixing in an inert solvent that does not substantially react with each component of the raw material, and then a method of removing the solvent can be used. Can be adopted. As the mixing device, a V-type mixer, a locking mixer, a ball mill, a vibration mill, a medium stirring mill and the like are preferably used.

(2) Baking step Next, the raw material mixture is fired. The raw material mixture is preferably fired in an inert gas atmosphere or a reducing gas atmosphere. The inert gas atmosphere can consist of a rare gas such as nitrogen or argon or an inert gas such as a mixed gas thereof. Since the atmosphere is an inert gas, it is desirable that oxygen is not contained, but oxygen may be contained as an impurity in an amount of less than 0.1 vol%, more preferably less than 0.01 vol%. Further, the reducing gas atmosphere can be composed of a mixed gas of a rare gas such as nitrogen or argon and a hydrogen gas or carbon monoxide gas. Since it is a reducing gas atmosphere, it is desirable that oxygen is not contained, but oxygen may be contained as an impurity in an amount of less than 0.1 vol%, more preferably less than 0.01 vol%. The firing temperature is in the range of 1500 to 2000 ° C, more preferably 1600 to 1800 ° C. The firing time is generally in the range of 0.5 to 100 hours, preferably in the range of 0.5 to 20 hours. The firing pressure may be at least normal pressure and preferably less than 0.92 MPa. By changing the type of atmospheric gas, the oxygen concentration and nitrogen concentration in the atmospheric gas, the firing temperature, and the setting of the firing time, the oxygen amount and nitrogen amount of the target phosphor can be adjusted.

(3) Crushing and Classification Steps The phosphor obtained by firing can obtain a desired particle size when used as a light emitting element of a white LED, for example, without requiring crushing, but other than that, if necessary. , Grinded and, in some cases, classified into the desired particle size range. In this case, the pulverization method may be either wet pulverization or dry pulverization, and the classification method may be any operation method generally used for powder classification, such as a sieving operation or an operation using a fluid. May be used. Further, the phosphor obtained by firing may be subjected to an acid cleaning treatment or a baking treatment with a mineral acid such as hydrochloric acid or nitric acid, if necessary.

3. 3. Light emitting device The phosphor of the present invention can be used in various light emitting devices. The light emitting device of the present invention includes at least a phosphor of the present invention containing 100 to 2500 ppm of boron in the composition represented by the above formula (1) and a light source that irradiates the phosphor with excitation light to emit light. Specific examples of the light emitting device include a white light emitting diode (white LED), a fluorescent lamp, a fluorescent display tube (VFD), a cathode ray tube (CRT), a plasma display panel (PDP), a field emission display (FED), and the like. it can. Among them, the white LED includes a blue phosphor, a red phosphor, a phosphor (green phosphor) of the present invention, and a semiconductor light emitting element that emits ultraviolet light having a wavelength of, for example, 350 to 430 nm, and the ultraviolet light from the light emitting element. It is a light emitting device that excites a blue phosphor, a green phosphor, and a red phosphor to obtain white by mixing blue, red, and green. Further, as another configuration, a red phosphor, a phosphor (green phosphor) of the present invention, and a semiconductor element that emits blue light having a wavelength of 430 to 500 nm are provided, and the blue light from the light emitting element is a green phosphor, red. It can also be applied to a light emitting device that excites a phosphor to obtain white with a mixture of blue, red, and green.

Examples of blue-emitting phosphors include (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu, (Ba, Sr, Ca) MgAl ₁₀ O ₁₇ : Eu, (Ba, Sr, Mg, Ca) ₁₀ (PO). ₄ ) ₆ (Cl, F) ₂ : Eu and the like can be mentioned. Examples of red-emitting phosphors include (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu, Mn, Y ₂ O ₂ S: Eu, La ₂ O ₃ S: Eu, (Ca, Sr, Ba). ) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu, Eu ₂ W ₂ O ₉ , (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, Mn, CaTIO ₃ : Pr, Bi, (La, Eu) ₂ W ₃ O _{12 and the} like can be mentioned. Examples of the semiconductor light emitting device include an AlGaN-based semiconductor light emitting device.

Hereinafter, the present invention will be specifically described based on examples, but these do not limit the object of the present invention. First, each measurement method used in this example is shown.

(Identification of crystal phase)
The crystal phase was identified using an X-ray diffraction (XRD) apparatus (Ultima IV manufactured by Rigaku Co., Ltd.).

(Measurement of particle size distribution)
The particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring device (MT3300EX II manufactured by Nikkiso Co., Ltd.).

(Scanning electron micrograph, Heywood diameter)
Scanning electron microscope photographs were taken using a scanning electron microscope (JSM-6510 manufactured by JEOL Ltd.). In addition, a scanning electron micrograph was read using the image analysis type particle size distribution measurement software "Mac-View" (manufactured by Mountech Co., Ltd.), and the Heywood diameter was calculated.

(Fluorescence peak wavelength, emission intensity, half width of spectrum)
The fluorescence spectrum at an excitation wavelength of 450 nm was measured using a spectral fluorometer (FP-6500, manufactured by Nippon Spectroscopy Co., Ltd.), and the fluorescence peak wavelength, the emission intensity at that wavelength, and the half-value width of the spectrum were determined. The emission intensity is shown with the emission intensity at the peak wavelength of 522.0 nm of Comparative Example 1 as 100%.

(Boron content)
The boron content in the phosphor powder was quantitatively analyzed using an inductively coupled plasma atomic emission spectroscopic analysis (ICP-AES) apparatus (SPS3250UV, manufactured by SII Nanotechnology Co., Ltd.).

(Concentration of element on the outermost surface of boron phosphor, concentration of element inside)
Elements present on the outermost surface of the phosphor (outside to number) under the condition that the X-ray source: Al-Kα and the extraction angle: 45 ° from the surface by the X-ray photoelectron spectroscopy (XPS) device (PHI1800 manufactured by ULVAC-PHI, Inc.). The element concentration on the outermost surface of the phosphor of boron was estimated from the peak intensity of each element.

(Comparative Example 1)
Europium oxide (Eu ₂ O ₃ ) powder (purity: 99.9%), strontium nitride (Sr ₃ N ₂ ) powder (purity: 99%), amorphous silicon nitride (Si ₃ N ₄ ) powder (purity: 9) 99%), aluminum nitride (AlN) powder (purity: 99.9%), lithium carbonate (Li ₂ CO ₃ ) powder (purity: 99.9%) was nitrogen purged to the mixed composition shown in Table 1. Weighed in a glove box and mixed for 1 hour using a dry vibrating mill to give a mixed powder. The obtained mixed powder is put into a crucible made of silicon nitride, charged into a graphite resistance heating type electric furnace, and after raising the temperature to 1650 ° C. while maintaining normal pressure while circulating nitrogen in the electric furnace. , 1650 ° C. for 7 hours, further heated to 1730 ° C., and held at 1730 ° C. for 10 hours to obtain a baked product. The obtained sample was crushed in a silicon nitride mortar until it passed through a sieve having a mesh size of 32 μm. Table 2 shows the evaluation results obtained by measuring XRD, particle size distribution, fluorescence spectrum, ICP, and XPS (PHI1800) of the obtained powder. The XRD pattern is shown in FIG. 1, the emission spectrum is shown in FIG. 2, and the scanning electron micrograph is shown in FIG.

As a result of the XRD measurement, the XRD pattern shown in FIG. 1 was obtained. The synthetic powder had a mixed phase of Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure and Sr Al Si ₄ N ₇ structure. The intensity (A) of the diffraction peak derived from the surface (021) near 25.8 ° of the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure and the intensity (A) of the diffraction peak near 24.9 ° of the Sr AlSi ₄ N ₇ structure (221). The ratio (B / A) of the diffraction peak derived from the plane to the intensity (B) was 2.75. As a result of particle size distribution _{measurement, D 10} diameter was 13.8Myuemu. As a result of ICP and XPS measurement, boron was not detected. When excited at a wavelength of 450 nm, the emission spectrum shown in FIG. 2 was obtained. The peak wavelength was 522.0 nm, which was green, but the half width was as wide as 111.1 nm, and the light emission contained a red component. Further, from the scanning electron micrograph shown in FIG. 3, in Comparative Example 1, the primary particle diameter before pulverization was large, the average value of the Heywood diameter was 35.9 μm, and pulverization was performed when classifying with a sieve having an opening of 32 μm. There was an increase in crushed debris because it had to be done.

(Examples 1 to 6)
Examples 1 to 6 were carried out in the same manner as in Comparative Example 1 except that boron nitride (BN) powder (purity: 99%) was added as shown in Table 1. Table 2 shows the evaluation results of the synthetic powder. As a result of XRD measurement, the intensity (A) of the diffraction peak derived from the (021) plane of the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure near 25.8 ° and the 24.9 ° of the Sr AlSi ₄ N ₇ structure. The ratio (B / A) of the diffraction peak derived from the nearby (221) plane to the intensity (B) is less than 0.03, and in particular, in Examples 2 to 6, the B / A is 0 and Sr. A single phase having a ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure was obtained. As a result of particle size distribution _{measurement, D 10} diameter was 14.6～24.5Myuemu. FIG. 1 shows the XRD pattern of Example 5.

As a result of ICP measurement, the boron content increased with the amount of boron added and was 110 to 2300 ppm. As a result of XPS measurement, the element concentration of boron on the outermost surface of the phosphor was 14,000 to 92,000 ppm. Further, the emission peak wavelength when excited at a wavelength of 450 nm is green with a wavelength of 520.5 to 524.0 nm, and the relative emission intensity when Comparative Example 1 is 100% is 132.5 to 194.9%. It was. The full width at half maximum of the emission spectrum was 67.3 to 76.4 nm. FIG. 2 shows the emission spectrum of Example 5, and FIG. 3 shows a scanning electron micrograph of Example 5.

In Examples 1 to 6, since the boron content is in the range of 100 to 2500 ppm, the single phase of the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure has few fine particles, and the emission spectrum has a narrow half width and high brightness. A phosphor was obtained. Further, from the scanning electron micrograph of Example 5 shown in FIG. 3 before pulverization, Example 5 had a smaller primary particle diameter than Comparative Example 1, and the average value of the Heywood diameter at this time was 26.8 μm. It was confirmed that the particles had a uniform particle size with few fine particles because they did not need to be crushed when they were classified with a sieve having a mesh size of 32 μm.

Further, the element concentration of boron on the surface of the sample of Example 5 after being Ar-etched to a depth of 200 nm in terms of SiO ₂ using an X-ray photoelectron spectroscopy (XPS) apparatus (PHI5000 manufactured by ULVAC-PHI, Inc.) was determined. , X-ray source: Al-Kα, extraction angle: 45 ° from the surface. The results are shown in Table 3 and FIG. The elemental concentration of boron on the outermost surface of the phosphor by XPS is 55,000 ppm, which decreases toward the inside of the particles, and the elemental concentration of boron at a depth of 100 nm or more from the outermost surface of the phosphor (measured on the surface after etching). Then, it was asymptotic to about 9000 ppm.

(Comparative Examples 2 to 4)
Comparative Examples 2 to 4 were carried out in the same manner as in Example 1 except that the amount of boron nitride (BN) powder (purity: 99%) added was changed as shown in Table 1. Table 2 shows the evaluation results of the synthetic powder. As a result of the XRD measurement, the intensity (A) of the diffraction peak derived from the (021) plane near 25.8 ° of the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure and the 24.9 ° of the Sr AlSi ₄ N ₇ structure. The ratio (B / A) of the diffraction peak derived from the nearby (221) plane to the intensity (B) is 0.04 to 0.21, and the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure and the Sr Al Si ₄ It has been a mixed phase of N ₇ structure. The result of the particle size distribution _{measurement, D 10} diameter was 11.5～17.0Myuemu. As a result of ICP measurement, the boron content was 54 ppm in Comparative Example 2, 84 ppm in Comparative Example 3, and 3600 ppm in Comparative Example 4. As a result of XPS measurement, the element concentration of boron on the outermost surface of the phosphor of Comparative Example 2 was 8000 ppm, the element concentration of boron on the outermost surface of the phosphor of Comparative Example 3 was 12000 ppm, and the element concentration on the outermost surface of the boron phosphor of Comparative Example 4 was. The element concentration was 120,000 ppm. The emission peak wavelength was green with a wavelength of 523.0 to 524.0 nm, and the relative emission intensity was 113.4 to 120.1% when Comparative Example 1 was taken as 100%. The full width at half maximum of the emission spectrum was 78.5-90.9 nm.

In Comparative Examples 2 to 4, since the boron content was outside the range of 100 to 2500 ppm, a high-luminance phosphor having a narrow half-value width of the emission spectrum could not be obtained.

Claims (9)

A phosphor containing a crystal phase represented by the composition of the following formula (1).
In addition, it contains 100-2500 ppm boron and
A phosphor having an elemental concentration of boron on the outermost surface of the phosphor measured by an X-ray photoelectron spectroscopy (XPS) apparatus of 20000 to 100,000 ppm.
_{Sr a M1 b Al c Si d} N e O f: Eu x1 Ce y1 ··· (1)
(Here, M1 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, 2 ≦ a ≦ 8, 0 ≦ b ≦ 3, 2 ≦ c ≦ 7, 10 ≦ d ≦ 25, 15 ≦ e ≦ 37, 0 ≦ f ≦ 3, 0 <x1 + y1 ≦ 0.6) The phosphor according to claim 1, wherein 4 ≦ a ≦ 8, 3 ≦ c ≦ 7, 15 ≦ d ≦ 25, 32 ≦ e ≦ 37. The phosphor according to any one of claims 1 to 3, wherein the half width of the emission spectrum is 70 nm or less. It is a phosphor containing a crystal phase having at least an Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure, and the element concentration of boron on the outermost surface of the phosphor measured by an X-ray photoelectron spectroscopy (XPS) apparatus is 20000 to 100,000 ppm.
The diffraction peak intensity derived from the (021) plane of the phosphor having the Sr ₅ Al ₅ Si ₂₁ N ₃₅ O ₂ structure in the X-ray diffraction pattern is derived from the (221) plane of the phosphor having the Sr AlSi ₄ N ₇ structure. A phosphor characterized in that B / A <0.03 when the diffraction peak intensity is B. A phosphor containing a crystal phase represented by the composition of the following formula (2), wherein the element concentration of boron on the outermost surface of the phosphor measured by an X-ray photoelectron spectroscopy (XPS) apparatus is 20000 to 100,000 ppm.
_{Sr g M2 h B i Al j} Si k N l O m: Eu x2 Ce y2 ··· (2)
(Here, M2 is one or more metal elements selected from the group consisting of Ca, Ba and Mg, and 2 ≦ g ≦ 8, 0 ≦ h ≦ 3, 0.02 ≦ i ≦ 0.8, 2 ≦ j ≦ 7, 10 ≦ k ≦ 25, 15 ≦ l ≦ 37, 0 ≦ m ≦ 3, 0 <x2 + y2 ≦ 0.6) The phosphor according to claim 6, wherein 4 ≦ g ≦ 8, 3 ≦ j ≦ 7, 15 ≦ k ≦ 25, and 32 ≦ l ≦ 37. The method for producing a phosphor according to any one of claims 1 to 7, wherein an Sr-containing compound, an Al-containing compound, a Si-containing compound, an Eu-containing compound and / or a Ce-containing compound, and a B-containing compound are mixed. And the process of obtaining the raw material mixture,
A method for producing a phosphor, which comprises a step of calcining the raw material mixture in an inert gas atmosphere or a reducing gas atmosphere.
A method for producing a phosphor, wherein the amount of the B-containing compound added is 250 to 10000 ppm of the raw material mixture. The method for producing a phosphor according to claim 8, wherein the Sr-containing compound is Sr ₃ N ₂ , the Al-containing compound is Al N, and the Si-containing compound is Si ₃ N ₄ . A light emitting device comprising the phosphor according to any one of claims 1 to 7 and a light source that irradiates the phosphor with excitation light to emit light.