WO2024101352A1 - Phosphor and light-emitting device - Google Patents

Phosphor and light-emitting device Download PDF

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WO2024101352A1
WO2024101352A1 PCT/JP2023/040042 JP2023040042W WO2024101352A1 WO 2024101352 A1 WO2024101352 A1 WO 2024101352A1 JP 2023040042 W JP2023040042 W JP 2023040042W WO 2024101352 A1 WO2024101352 A1 WO 2024101352A1
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phosphor
light
phosphor powder
less
powder
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PCT/JP2023/040042
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French (fr)
Japanese (ja)
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秀幸 江本
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デンカ株式会社
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  • the present invention relates to a phosphor and a light-emitting device.
  • a phosphor is usually used as a wavelength conversion material for obtaining white light from blue light emitted from a blue LED.
  • white LEDs Light Emitting Diode
  • phosphors capable of converting blue light into light with a longer wavelength is ongoing.
  • Patent Document 1 describes a phosphor represented by the general formula M x (Si,Al) 2 (N,O) 3 ⁇ y (wherein M is Li and one or more alkaline earth metal elements, 0.52 ⁇ x ⁇ 0.9, 0.06 ⁇ y ⁇ 0.23), in which M is partly substituted with Ce element, the Si/Al atomic ratio is 1.5 or more and 6 or less, the O/N atomic ratio is 0 or more and 0.1 or less, 5 to 50 mol % of M is Li, and 0.5 to 10 mol % of M is Ce.
  • M is Li and one or more alkaline earth metal elements, 0.52 ⁇ x ⁇ 0.9, 0.06 ⁇ y ⁇ 0.23
  • M is partly substituted with Ce element
  • the Si/Al atomic ratio is 1.5 or more and 6 or less
  • the O/N atomic ratio is 0 or more and 0.1 or less
  • 5 to 50 mol % of M is Li
  • 0.5 to 10 mol % of M is Ce.
  • the phosphor powder includes a surface alteration portion in which a part of the surface of the phosphor particle is raised.
  • the phosphor powder according to 1., The surface altered portion includes a flat structure. 3.
  • the phosphor powder wherein the surface alteration portion includes an oxide or a hydroxide.
  • the phosphor powder according to any one of 1. to 3. A phosphor powder, wherein when the particle diameter at the point where the cumulative volume from the small particle side is 50% in a volume frequency particle size distribution of the phosphor powder measured by a laser diffraction scattering method is defined as D50 , the D50 is 8 ⁇ m or more and 25 ⁇ m or less. 5.
  • the phosphor powder according to any one of 1. to 4. The phosphor is a phosphor powder configured such that 2 mol % or more and 5 mol % or less of M is Ce. 6.
  • the phosphor powder according to any one of 1. to 8. A phosphor having a half-width of a fluorescence peak of 130 nm or more and 142 nm or less when irradiated with an excitation light of 455 nm.
  • a light emitting device comprising the phosphor powder according to any one of 1. to 9. and a light source.
  • the present invention provides phosphor powder with excellent fluorescent properties and a light-emitting device using the same.
  • 1 is a schematic cross-sectional view showing an example of the structure of a light-emitting device.
  • 1 shows an SEM photograph of the phosphor powder of Example 1.
  • 4 shows an SEM photograph of the phosphor powder of Example 2.
  • 4 shows an SEM photograph of the phosphor powder of Example 3.
  • 1 shows an SEM photograph of the phosphor powder of Comparative Example 1.
  • 1 shows an SEM photograph of the phosphor powder of Comparative Example 2.
  • 1 shows an SEM photograph of the phosphor powder of Comparative Example 3.
  • X to Y in the explanation of a numerical range means from X to Y, unless otherwise specified.
  • X to Y in the explanation of a numerical range means from X to Y, unless otherwise specified.
  • 1 to 5% by mass means "1% by mass to 5% by mass.”
  • the phosphor powder of this embodiment contains phosphor particles represented by the general formula Mx (Si,Al) 2 (N,O) 3 ⁇ y , where M is Li and one or more alkaline earth metal elements, 0.52 ⁇ x ⁇ 0.90, 0 ⁇ y ⁇ 0.36, and a portion of M is substituted with Ce element.
  • the phosphor powder of this embodiment also includes a surface alteration portion in which at least a portion of the surface of the phosphor particle is raised.
  • the surface of phosphor particles represented by the general formula Mx (Si,Al) 2 (N,O) 3 ⁇ y can be appropriately modified by annealing in which phosphor particles in an open system are heated in a reducing gas atmosphere at a temperature relatively lower than the firing temperature, although the detailed mechanism is unclear.
  • annealing can provide phosphor particles having a plurality of surface altered portions formed on the phosphor particle surface.
  • phosphor powder containing phosphor particles having such surface altered portions on the surface thereof can improve luminescence characteristics such as internal quantum efficiency and diffuse reflectance at 600 nm, leading to the completion of the present invention.
  • the surface altered portion on the surface of the phosphor particle of this embodiment differs from the phosphor fragments described above in at least one of the following points: shape, attachment mode, and composition.
  • SEM photographs of phosphor particles show that the surface-altered portion does not have a fractured surface on the particle surface like a crushed piece, and may include a flat structure.
  • the surface-altered portion may also have a structure that does not have a constricted portion between the surface of the phosphor particle and the surface.
  • the surface-altered portion is formed on the surface of the phosphor particles by annealing the phosphor represented by the general formula Mx (Si,Al) 2 (N,O) 3 ⁇ y .
  • Mx (Si,Al) 2 (N,O) 3 ⁇ y the phosphor represented by the general formula Mx (Si,Al) 2 (N,O) 3 ⁇ y .
  • the multiple surface-altered portions may include a group of particles that are attached to one part of the surface of the phosphor particle at a distance from each other, or may be connected to each other to form a coating layer so that no part of the surface is exposed. In either case, it is preferable that at least a part of the surface of the phosphor particle has an exposed surface.
  • the multiple surface-altered portions may form multiple streaky coating layers, but the phosphor particle may not have a streaky coating layer.
  • the phosphor powder of this embodiment can also be used in such high-temperature environments.
  • the phosphor powder of this embodiment differs from the phosphor described in Patent Document 1 at least in that it contains a surface altered portion attached to the surface of the phosphor particle.
  • the phosphor of this embodiment has superior fluorescent properties compared to the phosphor described in Patent Document 1, and for example, in terms of internal quantum efficiency, it efficiently converts blue light into long-wavelength light.
  • the skeletal structure of the phosphor crystal is composed of (Si,Al)-(N,O) 4 regular tetrahedrons bonded together, with the M element located in the gap.
  • the composition of the above general formula is valid in a wide range in which electrical neutrality is maintained by the overall parameters of the valence and amount of the M element, the Si/Al ratio, and the N/O ratio.
  • the crystal structure of the phosphor of this embodiment is usually based on CaAlSiN 3 crystals.
  • M element is a combination of Li element and alkaline earth metal element, and a part of it is replaced with Ce element which is the luminescence center.
  • Li element the average valence of M element can be widely controlled by combination with divalent alkaline earth element and trivalent Ce element.
  • the ionic radius of Li + is very small, and the crystal size can be changed greatly depending on the amount, and various fluorescent emission can be obtained.
  • the coefficient x of the M element in the above general formula is 0.52 to 0.90, preferably 0.60 to 0.90, more preferably 0.70 to 0.90.
  • the coefficient x exceeds 0.9, that is, when it approaches CaAlSiN3 crystal, the fluorescence intensity tends to decrease, and when the coefficient x is smaller than 0.52, a large amount of a different phase other than the target crystal phase is generated, so that the fluorescence intensity tends to decrease significantly.
  • the coefficient y of (N, O) in the above general formula is preferably 0 or more and 0.36 or less, more preferably 0 or more and 0.30 or less, and even more preferably 0 or more and 0.23 or less. This increases the fluorescence intensity.
  • the O/N atomic ratio (molar ratio) is 0 or more and 0.1 or less, preferably 0.01 or more and 0.08 or less, and more preferably 0.02 or more and 0.07 or less. If the O/N atomic ratio is too large, the amount of heterophase generated increases, the luminous efficiency decreases, and the covalent bonding of the crystal decreases, which tends to cause deterioration of temperature characteristics (decreased brightness at high temperatures).
  • the Si/Al atomic ratio (molar ratio) is usually determined by the average valence and amount of the M element and the O/N atomic ratio being within a certain range.
  • the Si/Al atomic ratio is 1.5 to 6, preferably 2 to 4, and more preferably 2.5 to 4.
  • the Li content in the phosphor is 5 to 50 mol %, preferably 15 to 49 mol %, and more preferably 25 to 48 mol % of the element M.
  • the effect of Li is easily exhibited at 5 mol % or more, but if it exceeds 50 mol %, the intended crystal structure of the phosphor cannot be maintained and a different phase is generated, which tends to reduce the luminous efficiency.
  • the "Li content” refers to the Li content in the final phosphor, not the amount based on the raw material blend.
  • the Li compounds used as raw materials have high vapor pressure and are easily volatilized, and when attempting to synthesize nitrides and oxynitrides at high temperatures, a considerable amount of them volatilize. In other words, the Li content based on the raw material blend is significantly different from the content in the final product, so it does not refer to the Li content in the phosphor.
  • the content of Ce which is the luminescent center of the phosphor, is too low, its contribution to luminescence tends to be small, and if it is too high, concentration quenching of the phosphor due to energy transfer between Ce 3+ tends to occur. Therefore, the content of Ce is 2 to 5 mol %, preferably 2.5 to 5 mol %, of the M element.
  • the alkaline earth metal element used as the M element in the above general formula may be any element, but when Ca is used, high fluorescence intensity is obtained and the crystal structure is stabilized over a wide composition range. Therefore, it is preferable that the M element is Ca. It may also be a combination of multiple alkaline earth metal elements, for example, some of the Ca elements may be replaced with Sr elements.
  • the crystal structure of the phosphor is an orthorhombic system, and may be the same structure as the CaAlSiN3 crystal described above.
  • the crystal phase present in the phosphor is preferably the above-mentioned single crystal phase.
  • the phosphor may contain a different phase as long as it does not significantly affect the fluorescent properties.
  • Examples of different phases that have a low effect on the fluorescent properties when excited by blue light include ⁇ -sialon, AlN, LiSi 2 N 3 , and LiAlSi 2 N 4 .
  • the amount of different phases is preferably such that the diffraction intensity of the other crystal phases is 40% or less of the strongest diffraction intensity of the above-mentioned crystal phase when evaluated by powder X-ray diffraction method.
  • the phosphor of this embodiment is excited by light in a wide wavelength range from ultraviolet to visible light. For example, when irradiated with blue light having a wavelength of 455 nm, it may emit orange fluorescent light with a peak wavelength of 580 to 610 nm and a broad fluorescence spectrum with a half-width of 130 to 142 nm. Such a phosphor is suitable for use in a wide range of light emitting devices.
  • the phosphor of this embodiment has excellent heat resistance and chemical stability, and exhibits little decrease in luminance due to temperature rise, similar to conventional nitride/oxynitride phosphors such as CaAlSiN3 . Such characteristics are particularly suitable for applications requiring durability.
  • the diffuse reflectance X1 of the phosphor of this embodiment for light with a wavelength of 700 nm is preferably 89% or more and 98% or less, more preferably 91% or more and 98% or less, and particularly preferably 92% or more and 98% or less.
  • X1 is within such a numerical range, the luminous intensity tends to be increased.
  • the diffuse reflectance X2 of the phosphor of this embodiment for light of the fluorescent peak wavelength is preferably 88% or more and 97% or less, more preferably 90% or more and 97% or less, and particularly preferably 91% or more and 97% or less.
  • X2 is within such a numerical range, the luminous intensity tends to be increased.
  • the difference between X2 and X1 is preferably 3.0% or less, more preferably 2.0% or less, and particularly preferably 0.1% to 1.8%. This further improves the properties of the phosphor.
  • the difference between X3 and X1 is preferably 0.1% to 1.4%, more preferably 0.1% to 1.0%, and particularly preferably 0.1% to 0.8%. This further improves the properties of the phosphor.
  • the volume-based cumulative 50% diameter D50 (so-called median diameter) of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 8 ⁇ m or more and 25 ⁇ m or less, more preferably 10 ⁇ m or more and 20 ⁇ m or less, and even more preferably 12 ⁇ m or more and 20 ⁇ m or less.
  • the volume-based cumulative 10% diameter D10 of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 2 ⁇ m or more and 15 ⁇ m or less, more preferably 5 ⁇ m or more and 12 ⁇ m or less.
  • a relatively large value of D10 corresponds to a relatively small amount of fine powder (too fine phosphor particles that tend to reduce the blue light conversion efficiency) in the phosphor. Therefore, a relatively large value of D10 tends to increase the blue light conversion efficiency.
  • the volume-based cumulative 90% diameter D90 of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 15 ⁇ m or more and 50 ⁇ m or less, more preferably 18 ⁇ m or more and 40 ⁇ m or less.
  • a D90 that is not too large corresponds to a small amount of coarse particles in the phosphor.
  • a phosphor with a D90 that is not too large is effective in reducing chromaticity variation of a light-emitting device.
  • the light absorptance A 700 of the phosphor of this embodiment at a wavelength of 700 nm is preferably 1% or more and 10% or less, more preferably 2% or more and 9% or less, and particularly preferably 3% or more and 9% or less, thereby improving the internal quantum efficiency.
  • the light absorptance A 600 of the phosphor of this embodiment at a wavelength of 600 nm is preferably 1% or more and 13% or less, more preferably 2% or more and 12% or less, and even more preferably 3% or more and 11% or less. It is considered that the fluorescent properties are further improved when A 600 is not too large.
  • the internal quantum efficiency value of the phosphor of this embodiment with respect to excitation light of 455 nm is preferably 80% or more.
  • the external quantum efficiency value of the phosphor of this embodiment with respect to excitation light of 455 nm is preferably 70% or more.
  • the phosphor of this embodiment can be manufactured, for example, by a series of steps including the following (1) to (4).
  • the manufacturing process of the phosphor preferably includes an annealing treatment step (4).
  • Step of Preparing Raw Material Mixture Powder In the step of preparing the raw material mixture powder, usually, appropriate raw material powders are mixed to obtain the raw material mixture powder.
  • the raw material powder nitrides of the constituent elements, i.e., silicon nitride, aluminum nitride, lithium nitride, cerium nitride, and nitrides of alkaline earth elements (e.g., calcium nitride) are preferably used.
  • nitride powders are unstable in air, and the particle surfaces are covered with an oxide layer, so that even when a nitride raw material is used, a certain amount of oxide is ultimately contained in the raw material.
  • a part of the nitride may be made into an oxide (including a compound that becomes an oxide by heat treatment).
  • An example of an oxide is cerium oxide.
  • lithium compounds tend to volatilize significantly when heated, and depending on the sintering conditions, most of the compound may volatilize. Therefore, it is preferable to determine the amount of lithium compound to be mixed in accordance with the sintering conditions, taking into account the amount of volatilization during the sintering process.
  • nitride raw material powders lithium nitride, cerium nitride, and nitrides of alkaline earth elements react violently with moisture in the air, so it is preferable to handle these in a glove box substituted with an inert atmosphere. From the viewpoint of operational efficiency, it is preferable to (i) first weigh out predetermined amounts of silicon nitride, aluminum nitride and various oxide raw material powders that can be handled in air, and thoroughly mix them in advance in air to prepare a premixed powder, and (ii) then mix the premixed powder with a substance that easily reacts with moisture, such as lithium nitride, in a glove box to prepare the raw material mixed powder.
  • Raw Material Mixture Preparation Step is filled into an appropriate container and heated using a firing furnace or the like.
  • the firing temperature is preferably 1600 to 2000° C., more preferably 1700 to 1900° C., from the viewpoints of sufficiently promoting the reaction and suppressing the volatilization of lithium.
  • the baking time is preferably from 2 to 24 hours, more preferably from 4 to 16 hours, from the viewpoint of sufficiently promoting the reaction and suppressing the volatilization of lithium.
  • the firing step is preferably carried out under a nitrogen atmosphere. It is also preferable to appropriately adjust the pressure of the firing atmosphere. Specifically, the pressure of the firing atmosphere is preferably 0.5 MPa ⁇ G or more. When the firing temperature is particularly 1800° C. or more, the phosphor tends to decompose, but by increasing the pressure of the firing atmosphere, the decomposition of the phosphor can be suppressed. In consideration of industrial productivity, the pressure of the firing atmosphere is preferably less than 1 MPa ⁇ G.
  • the container for filling the raw material mixture powder is preferably made of a material that is stable in a high-temperature nitrogen atmosphere and does not react with the raw material mixture powder or its reaction products.
  • the material of the container is preferably boron nitride.
  • annealing treatment a predetermined amount of phosphor is placed in a crucible, and the phosphor is heated in a baking furnace in an atmosphere of reducing gas containing hydrogen gas at a predetermined temperature for a predetermined time.
  • the annealing temperature is lower than the above-mentioned firing temperature, and is preferably about 700 to 1200° C.
  • the annealing time is appropriately set according to the annealing temperature.
  • the atmosphere during annealing is preferably one having reducing properties, for example, one containing about 4 volume % of hydrogen gas (reducing gas) in nitrogen gas (inert gas).
  • a crucible without a lid and to have a low loading of phosphor in the crucible, which allows for sufficient contact between the mixed gas atmosphere and the phosphor surface during the annealing process. It is preferable to use a dense crucible made of alumina, which can prevent the components contained in the furnace from reacting with the crucible, thereby preventing unintended changes in the atmospheric environment. Although the detailed mechanism is unclear, it is believed that the surface of such a phosphor can be appropriately modified by annealing treatment in which the phosphor is heated in an open system at a relatively low temperature in a reducing mixed gas atmosphere.
  • a light emitting device can be obtained by combining the phosphor of this embodiment with a light source.
  • the luminescent light source typically emits ultraviolet or visible light.
  • the luminescent light source is a blue LED
  • the blue light emitted from the luminescent light source hits the phosphor, and the blue light is converted into light with a longer wavelength. That is, the phosphor of the present embodiment can be used as a wavelength conversion material that converts blue light into light with a longer wavelength.
  • the light emitting device 100 includes a light emitting element 120 (light emitting source), a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, a bonding wire 170, a bonding wire 172, and a composite body 40.
  • the light-emitting element 120 is a semiconductor element that emits excitation light.
  • the semiconductor element can be either a light-emitting diode (LED) or a light-emitting element (LD) equipped with a resonator.
  • LED light-emitting diode
  • LD light-emitting element
  • As the light-emitting element 120 for example, an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used.
  • the light emitting element 120 is mounted in a predetermined region on the upper surface of the heat sink 130. By mounting the light emitting element 120 on the heat sink 130, it is possible to improve the heat dissipation properties of the light emitting element 120. Note that a packaging substrate may be used instead of the heat sink 130.
  • One electrode (not shown) disposed on the upper surface side of the light emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire.
  • the other electrode (not shown) formed on the upper surface of the light emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.
  • the case 140 has a generally funnel-shaped recess whose diameter gradually increases from the bottom surface upward.
  • the light-emitting element 120 is provided on the bottom surface of the recess.
  • the wall surface of the recess surrounding the light-emitting element 120 acts as a reflector.
  • the composite 40 is filled in the recess whose wall is formed by the case 140.
  • the composite 40 is a wavelength conversion member that converts the excitation light emitted from the light emitting element 120 into light with a longer wavelength.
  • the composite 40 is obtained by dispersing at least the phosphor of this embodiment in an encapsulant 30 such as a resin. In order to obtain white light of higher quality, the encapsulant 30 may contain not only the phosphor of this embodiment but also other phosphors.
  • the light emitting device 100 emits a mixed color of light from the light emitting element 120 and light emitted from the phosphor particles 1 that are excited by absorbing the light emitted from the light emitting element 120. It is preferable that the light emitting device 100 emits white light by mixing the light from the light emitting element 120 and the light generated from the phosphor particles 1.
  • FIG. 1 shows a surface-mounted light-emitting device as an example
  • the light-emitting device is not limited to the surface-mounted type, and may be a bullet type, a COB (chip-on-board) type, or a CSP (chip-scale package) type.
  • the light-emitting device can be used in image display devices such as displays, and lighting devices.
  • a liquid crystal display can be manufactured using the light-emitting device 100 as a backlight.
  • a lighting device can also be manufactured using one or more light-emitting devices 100 with appropriate wiring.
  • the raw material mixed powder was filled into a boron nitride container.
  • the container was placed in a furnace, and the raw material mixed powder was sintered at 1800°C for 8 hours under a N2 atmosphere of 0.72 MPa ⁇ G.
  • Examples 1 and 2 and Comparative Example 2 The phosphor powder obtained in Comparative Example 1 was subjected to an annealing treatment under the conditions shown in Table 1 to obtain a phosphor powder.
  • the annealing treatment was carried out by filling a predetermined sample amount of phosphor powder into an alumina crucible (without a lid) according to the conditions shown in Table 1, and heating the phosphor powder filled in the crucible at a predetermined maximum temperature (wherein the temperature was increased from room temperature to the maximum temperature at a rate of 3°C/min) for a predetermined time in a predetermined firing furnace under a predetermined atmosphere shown in Table 1.
  • the phosphor powder was cooled from the maximum temperature to 500°C at about 1.3°C/min, cooled from 500°C to 300°C at about 1.1/°Cmin, and cooled in the furnace after 300°C.
  • the amount of sample was increased and the heating temperature was set higher than in Example 1.
  • an atmosphere filled with N2 gas without containing H2 gas was used.
  • a mixed gas of N2 gas and a predetermined amount of H2 gas was introduced at atmospheric pressure flow to fill the atmosphere.
  • Example 3 The phosphor powder obtained in Comparative Example 3 was subjected to an annealing treatment under the conditions shown in Table 1 to obtain a phosphor powder.
  • Comparative Example 2 A ⁇ -type sialon phosphor powder (manufactured by Denka, grade name: GR-MW540K8SD) was subjected to annealing treatment under the conditions shown in Table 1 to obtain a ⁇ -type sialon phosphor powder (after annealing treatment).
  • composition of some of the phosphor powders was analyzed as follows. Amounts of Ca, Li, Ce, Si and Al: The phosphor powder was dissolved by an alkali fusion method, and then the amounts were measured using an ICP emission spectrometer (5110VDV manufactured by Agilent). Amounts of O and N: Measured with an oxygen/nitrogen analyzer (HORIBA, EMGA-920). Based on the measurement results, x, y, the Si/Al atomic ratio, the O/N atomic ratio, the Li ratio of M, and the Ce ratio of M in the general formula Mx (Si,Al) 2 ( N,O)3 ⁇ y were determined.
  • XRD powder X-ray diffraction
  • FIG. 2 shows the phosphor powder of Example 1
  • FIG. 3 shows the phosphor powder of Example 2
  • FIG. 5 shows the phosphor powder of Comparative Example 1
  • FIG. 6 shows the phosphor powder of Comparative Example 2
  • FIG. 2 shows the phosphor powder of Example 1
  • FIG. 3 shows the phosphor powder of Example 2
  • FIG. 5 shows the phosphor powder of Comparative Example 1
  • FIG. 6 shows the phosphor powder of Comparative Example 2
  • Comparative Examples 1 to 3 the SEM photographs above confirmed that most of the surface of the phosphor particles was exposed as a smooth surface, with fragments formed by crushing the phosphor adhering to the smooth surface. It was also confirmed that washing the phosphor powders of Comparative Examples 1 to 3 with water removed the above-mentioned fragments to a certain extent from the phosphor particle surface.
  • Example 1 to 3 the above SEM photographs confirmed that there were multiple raised parts on the surface of the phosphor particles. Unlike the above-mentioned crushed pieces, the raised parts did not have a crushed surface, and some of them had a flat structure. Furthermore, as a result of chemical composition analysis of the above phosphor powder, the oxygen element amount (wt%) was higher in Examples 1 and 2 than in Comparative Example 1, and higher in Example 3 than in Comparative Example 3. It was confirmed that even if the phosphor powders of Examples 1 to 3 were washed with water, the above-mentioned raised portions were hardly removed from the surfaces of the phosphor particles after washing with water. From these results, it was determined that the raised portions formed on part of the surfaces of the phosphor particles were surface altered parts formed by the surface of the phosphor being altered by the above-mentioned annealing treatment.
  • the diffuse reflectance was measured using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). During the measurement, baseline correction was performed using a standard reflector (Spectralon). The solid sample holder filled with the phosphor powder was attached to a predetermined position in the apparatus, and the diffuse reflectance spectrum was measured in the wavelength range of 500 to 850 nm, and the diffuse reflectance was determined for light with wavelengths of 600 nm, 700 nm, and 800 nm, as well as for light with the fluorescent peak wavelength of the phosphor powder (described below).
  • the particle size distribution was measured by a laser diffraction scattering method in accordance with JIS R 1629: 1997 using an LS13 320 (manufactured by Beckman Coulter, Inc.) Water was used as the measurement solvent. Specifically, a small amount of phosphor powder was added to an aqueous solution containing 0.05% by mass of sodium hexametaphosphate as a dispersant. A dispersion was then prepared by dispersing the powder using a horn-type ultrasonic homogenizer (output: 300 W, horn diameter: 26 mm). An appropriate amount of this dispersion was added to a measurement solvent to measure the particle size distribution. From the obtained cumulative volume frequency distribution curve, the 10% volume diameter (D 10 ), 50% volume diameter (D 50 ), and 90% volume diameter (D 90 ) were obtained.
  • the fluorescence spectrum of the phosphor powder was measured using a spectrofluorophotometer (Hitachi High-Tech Science Corporation, F-7000) corrected with Rhodamine B and a secondary standard light source. Specifically, the spectrum of the fluorescence emitted by exciting the phosphor powder with monochromatic light of a wavelength of 455 nm was measured, and the fluorescence peak wavelength (nm) and the half-width (nm) at the fluorescence peak were obtained.
  • the internal quantum efficiency and external quantum efficiency of each phosphor powder were determined using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.) according to the following procedure.
  • MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.
  • the phosphor powder was filled into the recess of the concave cell so that the surface was smooth.
  • This concave cell was attached to a predetermined position (sample part) in the integrating sphere.
  • Monochromatic light which was split into a wavelength of 455 nm from a light emission source (Xe lamp), was introduced into the integrating sphere using an optical fiber.
  • This monochromatic light (excitation light) was irradiated onto the phosphor powder filled in the recess of the concave cell, and the fluorescence spectrum was measured. From the obtained spectral data, the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated. The number of excitation reflected light photons was calculated in the wavelength range of 450 nm to 465 nm, and the number of fluorescence photons was calculated in the wavelength range of 465 nm to 800 nm.
  • the number of photons (Qex) of the excitation light was calculated in the wavelength range of 595 to 610 nm.
  • the number of excited reflected photons (Qref) of the sample was calculated in the same manner as in (1) except that the standard reflector was replaced with a measurement sample.
  • the measurement sample was a phosphor powder filled in the recess of a concave cell so that the surface was smooth.
  • the light absorptance A 600 at a wavelength of 600 nm was calculated using the formula (Qex-Qref)/Qex (3).
  • the number of photons (Qex) of the excitation light was calculated in the wavelength range of 695 to 710 nm.
  • the number of excited reflected photons (Qref) of the sample was calculated in the same manner as in (1) except that the standard reflector was replaced with a measurement sample.
  • the measurement sample was a phosphor powder filled in the recess of a concave cell so that the surface was smooth.
  • the light absorptance A 700 at a wavelength of 700 nm was calculated using the formula (Qex-Qref)/Qex (3).
  • the phosphor powders of Examples 1 to 3 represented by the general formula M x (Si,Al) 2 (N,O) 3 ⁇ y showed superior luminescence characteristics such as internal quantum efficiency and diffuse reflectance at 600 nm compared to Comparative Examples 1 to 3.
  • the internal quantum efficiency and the diffuse reflectance at 600 nm were significantly decreased compared to before the annealing treatment.

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Abstract

The phosphor powder according to the present invention contains particles of a phosphor that is represented by the general formula Mx (Si, Al)2 (N, O)3 ± y (where M is Li and one or more alkaline earth metal elements, 0.52 ≤ x ≤ 0.90, and 0 ≤ y ≤ 0.36) and in which part of M is substituted by Ce, wherein the phosphor powder contains a surface modified part in which a part of the surface of the phosphor particles protrudes.

Description

蛍光体、および発光装置Phosphor and light-emitting device
　本発明は、蛍光体、および発光装置に関する。 The present invention relates to a phosphor and a light-emitting device.
　白色ＬＥＤ（Ｌｉｇｈｔ　Ｅｍｉｔｔｉｎｇ　Ｄｉｏｄｅ）を製造するために、通常、蛍光体が用いられる。すなわち、青色ＬＥＤから発せられる青色光から白色光を得るための波長変換材料として、蛍光体が用いられる。
　照明用途での白色ＬＥＤの普及や、画像表示装置への白色ＬＥＤの適用検討などに伴い、青色光をより長波長の光に変換可能な蛍光体の開発が継続されている。 2. Description of the Related Art In order to manufacture a white LED (Light Emitting Diode), a phosphor is usually used as a wavelength conversion material for obtaining white light from blue light emitted from a blue LED.
Along with the widespread use of white LEDs for lighting purposes and the consideration of the application of white LEDs to image display devices, the development of phosphors capable of converting blue light into light with a longer wavelength is ongoing.
　このような蛍光体の１つとして、例えば、特許文献１には、一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙ（ただし、ＭはＬｉ及び一種以上のアルカリ土類金属元素であり、０．５２≦ｘ≦０．９、０．０６≦ｙ≦０．２３）で示され、Ｍの一部がＣｅ元素で置換されている蛍光体であって、Ｓｉ／Ａｌ原子比が１．５以上６以下であり、かつＯ／Ｎ原子比が０以上０．１以下であり、Ｍの５～５０ｍｏｌ％がＬｉであり、Ｍの０．５～１０ｍｏｌ％がＣｅである蛍光体が記載されている。 As one such phosphor, for example, Patent Document 1 describes a phosphor represented by the general formula M x (Si,Al) 2 (N,O) 3±y (wherein M is Li and one or more alkaline earth metal elements, 0.52≦x≦0.9, 0.06≦y≦0.23), in which M is partly substituted with Ce element, the Si/Al atomic ratio is 1.5 or more and 6 or less, the O/N atomic ratio is 0 or more and 0.1 or less, 5 to 50 mol % of M is Li, and 0.5 to 10 mol % of M is Ce.
特許第５９６９３９１号公報Patent No. 5969391
　しかしながら、本発明者が検討した結果、上記特許文献１に記載の蛍光体において、蛍光特性の点で改善の余地があることが判明した。 However, as a result of the inventor's investigations, it was found that there is room for improvement in terms of the fluorescent properties of the phosphor described in Patent Document 1.
　本発明者は、蛍光特性に優れた蛍光体粉末を提供することを目的の１つとして、今回、検討を行った。 The inventors conducted this study with the aim of providing a phosphor powder with excellent fluorescent properties.
　本発明者らは、検討の結果、以下に提供される発明を完成させた。 As a result of their investigations, the inventors have completed the invention provided below.
　本発明の一態様によれば、以下の蛍光体、および発光装置が提供される。
１．　一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙ（ただし、ＭはＬｉ及び一種以上のアルカリ土類金属元素であり、０．５２≦ｘ≦０．９０、０≦ｙ≦０．３６）で示され、Ｍの一部がＣｅ元素で置換されている蛍光体の粒子を含む蛍光体粉末であって、
　前記蛍光体の粒子の表面の一部が隆起している表面変質部を含む、蛍光体粉末。
２．　１．に記載の蛍光体粉末であって、
　前記表面変質部が、扁平状構造を含む、蛍光体粉末。
３．　１．又は２．に記載の蛍光体粉末であって、
　前記表面変質部が、酸化物または水酸化物を含む、蛍光体粉末。
４．　１．～３．のいずれか一つに記載の蛍光体粉末であって、
　レーザー回折散乱法で測定される当該蛍光体粉末の体積頻度粒度分布において、小粒子側からの累積体積が５０％となる点の粒子径をＤ５０としたとき、Ｄ５０が８μｍ以上２５μｍ以下である、蛍光体粉末。
５．　１．～４．のいずれか一つに記載の蛍光体粉末であって、
　前記蛍光体は、Ｍの２ｍｏｌ％以上５以下ｍｏｌ％がＣｅとなるように構成される、蛍光体粉末。
６．　１．～５．のいずれか一つに記載の蛍光体粉末であって、
　５００～８５０ｎｍの波長範囲で当該蛍光体の拡散反射率スペクトルを測定したとき、波長７００ｎｍの光に対する拡散反射率Ｘ１と、４５５ｎｍの励起光を照射したときの蛍光ピーク波長の光に対する拡散反射率Ｘ２と、の差分Ｘ１－Ｘ２が、３．０％以下である蛍光体。
７．　１．～６．のいずれか一つに記載の蛍光体粉末であって、
　４５５ｎｍの励起光を照射したときの蛍光ピーク波長の光に対する拡散反射率Ｘ２が、８８％以上９７％以下である蛍光体。
８．　１．～７．のいずれか一つに記載の蛍光体粉末であって、
　４５５ｎｍの励起光を照射したときの蛍光ピークの波長が、５８０ｎｍ以上６１０ｎｍ以下である、蛍光体。
９．　１．～８．のいずれか一つに記載の蛍光体粉末であって、
　４５５ｎｍの励起光を照射したときの蛍光ピークの半値幅が、１３０ｎｍ以上１４２ｎｍ以下である、蛍光体。
１０．　１．～９．のいずれか一つに記載の蛍光体粉末と発光光源とを備える発光装置。 According to one aspect of the present invention, there is provided the following phosphor and light emitting device.
1. A phosphor powder containing particles of a phosphor represented by the general formula Mx (Si,Al) 2 (N,O) 3±y (wherein M is Li and one or more alkaline earth metal elements, 0.52≦x≦0.90, 0≦y≦0.36), in which a part of M is substituted with a Ce element,
The phosphor powder includes a surface alteration portion in which a part of the surface of the phosphor particle is raised.
2. The phosphor powder according to 1.,
The surface altered portion includes a flat structure.
3. The phosphor powder according to 1. or 2.,
The phosphor powder, wherein the surface alteration portion includes an oxide or a hydroxide.
4. The phosphor powder according to any one of 1. to 3.,
A phosphor powder, wherein when the particle diameter at the point where the cumulative volume from the small particle side is 50% in a volume frequency particle size distribution of the phosphor powder measured by a laser diffraction scattering method is defined as D50 , the D50 is 8 μm or more and 25 μm or less.
5. The phosphor powder according to any one of 1. to 4.,
The phosphor is a phosphor powder configured such that 2 mol % or more and 5 mol % or less of M is Ce.
6. The phosphor powder according to any one of 1. to 5.,
A phosphor in which, when the diffuse reflectance spectrum of the phosphor is measured in the wavelength range of 500 to 850 nm, the difference X1-X2 between the diffuse reflectance X1 for light with a wavelength of 700 nm and the diffuse reflectance X2 for light with a fluorescence peak wavelength when irradiated with excitation light of 455 nm is 3.0% or less.
7. The phosphor powder according to any one of 1. to 6.,
A phosphor having a diffuse reflectance X2 of 88% or more and 97% or less for light having a fluorescence peak wavelength when irradiated with excitation light of 455 nm.
8. The phosphor powder according to any one of 1. to 7.,
A phosphor having a fluorescence peak wavelength of 580 nm or more and 610 nm or less when irradiated with 455 nm excitation light.
9. The phosphor powder according to any one of 1. to 8.,
A phosphor having a half-width of a fluorescence peak of 130 nm or more and 142 nm or less when irradiated with an excitation light of 455 nm.
10. A light emitting device comprising the phosphor powder according to any one of 1. to 9. and a light source.
　本発明によれば、蛍光特性に優れた蛍光体粉末、それを用いた発光装置が提供される。 The present invention provides phosphor powder with excellent fluorescent properties and a light-emitting device using the same.
発光装置の構造の一例を示す概略断面図である。1 is a schematic cross-sectional view showing an example of the structure of a light-emitting device. 実施例１の蛍光体粉末のＳＥＭ写真を示す。1 shows an SEM photograph of the phosphor powder of Example 1. 実施例２の蛍光体粉末のＳＥＭ写真を示す。4 shows an SEM photograph of the phosphor powder of Example 2. 実施例３の蛍光体粉末のＳＥＭ写真を示す。4 shows an SEM photograph of the phosphor powder of Example 3. 比施例１の蛍光体粉末のＳＥＭ写真を示す。1 shows an SEM photograph of the phosphor powder of Comparative Example 1. 比施例２の蛍光体粉末のＳＥＭ写真を示す。1 shows an SEM photograph of the phosphor powder of Comparative Example 2. 比施例３の蛍光体粉末のＳＥＭ写真を示す。1 shows an SEM photograph of the phosphor powder of Comparative Example 3.
　以下、本発明の実施の形態について、図面を用いて説明する。なお、すべての図面において、同様な構成要素には同様の符号を付し、適宜説明を省略する。また、図は概略図であり、実際の寸法比率とは一致していない。 Below, an embodiment of the present invention will be described with reference to the drawings. Note that in all drawings, similar components are given similar reference symbols and descriptions will be omitted where appropriate. Also, the drawings are schematic and do not correspond to the actual dimensional ratios.
　本明細書中、数値範囲の説明における「Ｘ～Ｙ」との表記は、特に断らない限り、Ｘ以上Ｙ以下のことを表す。例えば、「１～５質量％」とは「１質量％以上５質量％以下」を意味する。 In this specification, the notation "X to Y" in the explanation of a numerical range means from X to Y, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass to 5% by mass."
＜蛍光体＞
　本実施形態の蛍光体粉末は、一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙで表される蛍光体の粒子を含み、一般式中、ＭはＬｉ及び一種以上のアルカリ土類金属元素、０．５２≦ｘ≦０．９０、０≦ｙ≦０．３６でり、Ｍの一部はＣｅ元素で置換されている。 <Phosphor>
The phosphor powder of this embodiment contains phosphor particles represented by the general formula Mx (Si,Al) 2 (N,O) 3±y , where M is Li and one or more alkaline earth metal elements, 0.52≦x≦0.90, 0≦y≦0.36, and a portion of M is substituted with Ce element.
　また本実施形態の蛍光体粉末は、蛍光体の粒子の表面の少なくとも一部が隆起している表面変質部を含む。 The phosphor powder of this embodiment also includes a surface alteration portion in which at least a portion of the surface of the phosphor particle is raised.
　本発明者の知見によれば、還元性ガス雰囲気中、焼成温度よりも比較的低温にて、開放系にある蛍光体粒子を加熱するというアニール処理により、詳細なメカニズムは定かではないが、一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙで表される蛍光体粒子の表面を適切に改質できることが判明した。すなわち、かかるアニール処理により、蛍光体の粒子表面に表面変質部が複数形成された蛍光体粒子が得られる。
　このような表面変質部を表面に有する蛍光体粒子を含む蛍光体粉末は、内部量子効率や６００ｎｍにおける拡散反射率等の発光特性を向上できることが判明し、本発明が完成するに至った。 According to the findings of the present inventors, it has been found that the surface of phosphor particles represented by the general formula Mx (Si,Al) 2 (N,O) 3±y can be appropriately modified by annealing in which phosphor particles in an open system are heated in a reducing gas atmosphere at a temperature relatively lower than the firing temperature, although the detailed mechanism is unclear. In other words, such annealing can provide phosphor particles having a plurality of surface altered portions formed on the phosphor particle surface.
It has been found that phosphor powder containing phosphor particles having such surface altered portions on the surface thereof can improve luminescence characteristics such as internal quantum efficiency and diffuse reflectance at 600 nm, leading to the completion of the present invention.
　通常、蛍光体粉末の製造工程中の破砕処理により蛍光体の破砕片が形成されて、この破砕片が蛍光体粒子に付着することが知られている。しかしながら、アニール処理を実施しない場合、蛍光体粒子の表面に蛍光体の破砕片が付着するが、表面変質部は形成されないことが本発明者により確認された。 It is known that phosphor fragments are usually formed during the crushing process in the phosphor powder manufacturing process, and these fragments adhere to the phosphor particles. However, the inventors have confirmed that when the annealing process is not performed, phosphor fragments adhere to the surface of the phosphor particles, but no surface alteration is formed.
　本実施形態の蛍光体粒子の表面にある表面変質部は、上記の蛍光体の破砕片とは、形状、付着態様および組成の少なくとも１点以上の点で相違する。 The surface altered portion on the surface of the phosphor particle of this embodiment differs from the phosphor fragments described above in at least one of the following points: shape, attachment mode, and composition.
　蛍光体粒子のＳＥＭ写真により、表面変質部は、破砕片のように粒子表面に破砕面を有さず、扁平状構造を含んでもよい。また、表面変質部は、蛍光体粒子の表面と間にくびれ部分を有さない構造を有してもよい。 SEM photographs of phosphor particles show that the surface-altered portion does not have a fractured surface on the particle surface like a crushed piece, and may include a flat structure. The surface-altered portion may also have a structure that does not have a constricted portion between the surface of the phosphor particle and the surface.
　表面変質部の多くは、蛍光体粒子の水洗により表面から脱落しないで、表面に付着したままの状態となる。一方の破砕片の多くは、蛍光体粒子の水洗により表面から脱落する。表面変質部は、蛍光体粒子の表面に化学的および／または物理的に破砕片よりも強く付着する。 Most of the surface-altered parts do not fall off from the surface of the phosphor particles when they are washed with water, but remain attached to the surface. On the other hand, most of the crushed fragments fall off from the surface of the phosphor particles when they are washed with water. The surface-altered parts are chemically and/or physically more strongly attached to the surface of the phosphor particles than the crushed fragments.
　また、蛍光体粉末の化学組成分析の結果、上記アニール処理後の酸素含有量が、アニール処理前と比べて、高くなることが判明した。このような結果から、詳細なメカニズムは定かではないが、表面変質部は、蛍光体の粒子の表面が改質したものとして、蛍光体の酸化物または水酸化物を含むと考えられる。 In addition, chemical composition analysis of the phosphor powder revealed that the oxygen content after the annealing treatment was higher than before the annealing treatment. From these results, although the detailed mechanism is unclear, it is believed that the surface alteration area contains oxides or hydroxides of the phosphor as a modified surface of the phosphor particles.
　なお、表面変質部は、一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙで表される蛍光体をアニール処理することにより蛍光体粒子の表面に形成される。一方、結晶相がβ相のサイアロン蛍光体（いわゆるβ型サイアロン蛍光体）をアニール処理したとしても、その表面に表面変質部は形成されないことが確認されている。なお、β型サイアロン蛍光体の粒子表面には、付着するものがあるとしても、蛍光体の破砕片が挙げられる。 The surface-altered portion is formed on the surface of the phosphor particles by annealing the phosphor represented by the general formula Mx (Si,Al) 2 (N,O) 3±y . On the other hand, it has been confirmed that even if a sialon phosphor having a β-phase crystal phase (so-called β-type sialon phosphor) is annealed, no surface-altered portion is formed on the surface. If anything adheres to the particle surface of the β-type sialon phosphor, it is only crushed pieces of the phosphor.
　蛍光体粒子のＳＥＭ写真により、複数の表面変質部は、蛍光体粒子の一つの表面において、表面の一部に互いに離間して付着した状態である粒子群を含んでもよいが、表面の一部が露出しないように互いに連結して被覆層を形成してもよい。いずれの場合も、蛍光体粒子の表面の少なくとも一部には、表面が露出している部分を有することが好ましい。また、複数の表面変質部が複数の筋状の被覆層を形成してもよいが、蛍光体粒子が筋状の被覆層を有しないでもよい。 In SEM photographs of phosphor particles, the multiple surface-altered portions may include a group of particles that are attached to one part of the surface of the phosphor particle at a distance from each other, or may be connected to each other to form a coating layer so that no part of the surface is exposed. In either case, it is preferable that at least a part of the surface of the phosphor particle has an exposed surface. In addition, the multiple surface-altered portions may form multiple streaky coating layers, but the phosphor particle may not have a streaky coating layer.
　近年、発光装置において高出力化・低背化が進められており、蛍光体が実装される発光装置中の動作環境は、ますます高温となる傾向にある。
　本実施形態の蛍光体粉末は、このような高温環境での使用にも用いることができる。 In recent years, light emitting devices have been developed to have higher output and lower height, and the operating environment within the light emitting device in which phosphors are mounted tends to become increasingly hot.
The phosphor powder of this embodiment can also be used in such high-temperature environments.
　本実施形態の蛍光体粉末は、少なくとも、蛍光体粒子の表面に付着した表面変質部を含む点でおいて、特許文献１に記載された蛍光体と相違する。本実施形態の蛍光体は、特許文献１に記載された蛍光体に比べて、蛍光特性に優れており、例えば、内部量子効率の点で、青色光を効率よく長波長の光に変換する。 The phosphor powder of this embodiment differs from the phosphor described in Patent Document 1 at least in that it contains a surface altered portion attached to the surface of the phosphor particle. The phosphor of this embodiment has superior fluorescent properties compared to the phosphor described in Patent Document 1, and for example, in terms of internal quantum efficiency, it efficiently converts blue light into long-wavelength light.
　本実施形態の蛍光体に関する説明を続ける。 　We will continue with the explanation of the phosphor of this embodiment.
（結晶構造、化学組成など）
　蛍光体結晶の骨格構造は、（Ｓｉ，Ａｌ）－（Ｎ，Ｏ）４正四面体が結合することにより構成されており、その間隙にＭ元素が位置するものである。上記一般式の組成は、Ｍ元素の価数と量、Ｓｉ／Ａｌ比、Ｎ／Ｏ比のパラメータの全体により電気的中性が保たれる幅広い範囲で成立する。上記一般式で示される代表的な蛍光体として、Ｍ元素がＣａでｘ＝１、更にＳｉ／Ａｌ＝１、Ｏ／Ｎ＝０となるＣａＡｌＳｉＮ３がある。ＣａＡｌＳｉＮ３のＣａの一部がＥｕで置換された場合には赤色蛍光体に、Ｃｅで置換された場合には黄～橙色蛍光体になる。 (Crystal structure, chemical composition, etc.)
The skeletal structure of the phosphor crystal is composed of (Si,Al)-(N,O) 4 regular tetrahedrons bonded together, with the M element located in the gap. The composition of the above general formula is valid in a wide range in which electrical neutrality is maintained by the overall parameters of the valence and amount of the M element, the Si/Al ratio, and the N/O ratio. A representative phosphor represented by the above general formula is CaAlSiN 3 , in which the M element is Ca and x=1, Si/Al=1, and O/N=0. When part of the Ca in CaAlSiN 3 is replaced with Eu, it becomes a red phosphor, and when it is replaced with Ce, it becomes a yellow to orange phosphor.
　本実施形態の蛍光体の結晶構造は、通常、ＣａＡｌＳｉＮ３結晶をベースとしたものである。この蛍光体の特徴の１つは、Ｃｅ付活でも非常に高い発光効率が得られるように構成元素、組成を大きく変えた点にある。
　上記一般式において、Ｍ元素はＬｉ元素とアルカリ土類金属元素の組み合わせであり、その一部が発光中心となるＣｅ元素で置換されている。Ｌｉ元素を用いることにより、二価のアルカリ土類元素及び三価のＣｅ元素との組み合わせにより、Ｍ元素の平均価数を幅広く制御できる。また、Ｌｉ＋のイオン半径は非常に小さく、その量により結晶サイズを大きく変化させることができ、多様な蛍光発光が得られる。
　上記一般式におけるＭ元素の係数ｘは、０．５２以上０．９０以下、好ましくは０．６０以上０．９０以下、より好ましくは０．７０以上０．９０以下である。係数ｘが０．９を越える、つまりＣａＡｌＳｉＮ３結晶に近づくと蛍光強度が低下する傾向にあり、係数ｘが０．５２よりも小さいと、目的とする結晶相以外の異相が多量に生成するために蛍光強度が著しく低下する傾向がある。 The crystal structure of the phosphor of this embodiment is usually based on CaAlSiN 3 crystals. One of the features of this phosphor is that the constituent elements and composition have been significantly changed so that very high luminous efficiency can be obtained even with Ce activation.
In the above general formula, M element is a combination of Li element and alkaline earth metal element, and a part of it is replaced with Ce element which is the luminescence center. By using Li element, the average valence of M element can be widely controlled by combination with divalent alkaline earth element and trivalent Ce element. In addition, the ionic radius of Li + is very small, and the crystal size can be changed greatly depending on the amount, and various fluorescent emission can be obtained.
The coefficient x of the M element in the above general formula is 0.52 to 0.90, preferably 0.60 to 0.90, more preferably 0.70 to 0.90. When the coefficient x exceeds 0.9, that is, when it approaches CaAlSiN3 crystal, the fluorescence intensity tends to decrease, and when the coefficient x is smaller than 0.52, a large amount of a different phase other than the target crystal phase is generated, so that the fluorescence intensity tends to decrease significantly.
　上記一般式における（Ｎ，Ｏ）の係数ｙは、０以上０．３６以下が好ましく、０以上０．３０以下がより好ましく、０以上０．２３以下がさらに好ましい。これにより、蛍光強度を高められる。 The coefficient y of (N, O) in the above general formula is preferably 0 or more and 0.36 or less, more preferably 0 or more and 0.30 or less, and even more preferably 0 or more and 0.23 or less. This increases the fluorescence intensity.
　本実施形態において、Ｏ／Ｎ原子比（モル比）は、０以上０．１以下、好ましくは０．０１以上０．０８以下、さらに好ましくは０．０２以上０．０７以下である。Ｏ／Ｎ原子比があまりに大きいと異相生成量が増大し、発光効率が低下するとともに、結晶の共有結合性が低下し、温度特性の悪化（高温での輝度低下）を引き起こす傾向にある。 In this embodiment, the O/N atomic ratio (molar ratio) is 0 or more and 0.1 or less, preferably 0.01 or more and 0.08 or less, and more preferably 0.02 or more and 0.07 or less. If the O/N atomic ratio is too large, the amount of heterophase generated increases, the luminous efficiency decreases, and the covalent bonding of the crystal decreases, which tends to cause deterioration of temperature characteristics (decreased brightness at high temperatures).
　Ｓｉ／Ａｌ原子比（モル比）に関しては、通常、Ｍ元素の平均価数や量、および、Ｏ／Ｎ原子比を所定の範囲とすると必然的に決められる。Ｓｉ／Ａｌ原子比は１．５以上６以下、好ましくは２以上４以下、より好ましくは２．５以上４以下である。 The Si/Al atomic ratio (molar ratio) is usually determined by the average valence and amount of the M element and the O/N atomic ratio being within a certain range. The Si/Al atomic ratio is 1.5 to 6, preferably 2 to 4, and more preferably 2.5 to 4.
　蛍光体中のＬｉ含有量は、Ｍ元素の５～５０ｍｏｌ％、好ましくは１５～４９ｍｏｌ％、さらに好ましくは２５～４８ｍｏｌ％である。Ｌｉの効果は５ｍｏｌ％以上で発揮されやすいが、５０ｍｏｌ％を越えると目的とする蛍光体の結晶構造が維持できず異相を生成してしまい、発光効率が低下しやすい。
　念のため述べておくと、「Ｌｉ含有量」とは、最終的に得られる蛍光体中のＬｉ含有量であり、原料配合ベースの量ではない。原料に使用するＬｉ化合物は蒸気圧が高く揮発しやすく、高温で窒化物・酸窒化物を合成しようとした場合、相当な量が揮発する。つまり、原料配合ベースのＬｉ量は最終生成物中の含有量とは大きく乖離しているので、蛍光体中のＬｉ含有量を意味しない。 The Li content in the phosphor is 5 to 50 mol %, preferably 15 to 49 mol %, and more preferably 25 to 48 mol % of the element M. The effect of Li is easily exhibited at 5 mol % or more, but if it exceeds 50 mol %, the intended crystal structure of the phosphor cannot be maintained and a different phase is generated, which tends to reduce the luminous efficiency.
Just to be clear, the "Li content" refers to the Li content in the final phosphor, not the amount based on the raw material blend. The Li compounds used as raw materials have high vapor pressure and are easily volatilized, and when attempting to synthesize nitrides and oxynitrides at high temperatures, a considerable amount of them volatilize. In other words, the Li content based on the raw material blend is significantly different from the content in the final product, so it does not refer to the Li content in the phosphor.
　蛍光体の発光中心であるＣｅの含有量は、あまりに少ないと発光への寄与が小さくなる傾向にあり、あまりに多いとＣｅ３＋間のエネルギー伝達による蛍光体の濃度消光が起こる傾向にある。よって、Ｃｅの含有量は、Ｍ元素の２～５ｍｏｌ％、好ましくは２．５～５ｍｏｌ％である。 If the content of Ce, which is the luminescent center of the phosphor, is too low, its contribution to luminescence tends to be small, and if it is too high, concentration quenching of the phosphor due to energy transfer between Ce 3+ tends to occur. Therefore, the content of Ce is 2 to 5 mol %, preferably 2.5 to 5 mol %, of the M element.
　上記一般式におけるＭ元素として用いられるアルカリ土類金属元素は、いずれの元素でも構わないが、Ｃａを用いた場合に、高い蛍光強度が得られ、幅広い組成範囲で結晶構造が安定化する。よって、Ｍ元素はＣａであることが好ましい。複数のアルカリ土類金属元素の組み合わせであってもよく、例えばＣａ元素の一部がＳｒ元素に置き換わってもよい。 The alkaline earth metal element used as the M element in the above general formula may be any element, but when Ca is used, high fluorescence intensity is obtained and the crystal structure is stabilized over a wide composition range. Therefore, it is preferable that the M element is Ca. It may also be a combination of multiple alkaline earth metal elements, for example, some of the Ca elements may be replaced with Sr elements.
　蛍光体の結晶構造は、斜方晶系であり、前述したＣａＡｌＳｉＮ３結晶と同一の構造であってよい。ＣａＡｌＳｉＮ３結晶の格子定数は、一例として、ａ＝０．９８００７ｎｍ、ｂ＝０．５６４９７ｎｍ、ｃ＝０．５０６２７ｎｍである。本実施形態において、格子定数は、通常、ａ＝０．９３５００～０．９６５００ｎｍ、ｂ＝０．５５０００～０．５７０００ｎｍ、ｃ＝０．４８０００～０．５００００ｎｍであり、ＣａＡｌＳｉＮ３結晶に比べ、いずれも小さい値となる。この格子定数の範囲は、前述した構成元素及び組成を反映したものである。 The crystal structure of the phosphor is an orthorhombic system, and may be the same structure as the CaAlSiN3 crystal described above. The lattice constants of the CaAlSiN3 crystal are, for example, a = 0.98007 nm, b = 0.56497 nm, and c = 0.50627 nm. In this embodiment, the lattice constants are usually a = 0.93500 to 0.96500 nm, b = 0.55000 to 0.57000 nm, and c = 0.48000 to 0.50000 nm, all of which are smaller than those of the CaAlSiN3 crystal. This range of lattice constants reflects the aforementioned constituent elements and composition.
　蛍光体中に存在する結晶相は、上記の結晶単相が好ましい。ただし、蛍光特性に大きい影響がない限り、蛍光体は異相を含んでいても構わない。青色光励起の場合に蛍光特性への影響が低い異相としては、αサイアロン、ＡｌＮ、ＬｉＳｉ２Ｎ３、ＬｉＡｌＳｉ２Ｎ４などが挙げられる。異相の量は、粉末Ｘ線回折法で評価した際の上記結晶相の最強回折線強度に対する他の結晶相の回折線強度が４０％以下であるような量であることが好ましい。 The crystal phase present in the phosphor is preferably the above-mentioned single crystal phase. However, the phosphor may contain a different phase as long as it does not significantly affect the fluorescent properties. Examples of different phases that have a low effect on the fluorescent properties when excited by blue light include α-sialon, AlN, LiSi 2 N 3 , and LiAlSi 2 N 4 . The amount of different phases is preferably such that the diffraction intensity of the other crystal phases is 40% or less of the strongest diffraction intensity of the above-mentioned crystal phase when evaluated by powder X-ray diffraction method.
　本実施形態の蛍光体は、紫外～可視光の幅広い波長域の光で励起される。例えば波長４５５ｎｍの青色光が照射された場合に、ピーク波長が５８０～６１０ｎｍの橙色で、蛍光スペクトルの半値幅が１３０～１４２ｎｍのブロードな蛍光発光を示すことがある。
　このような蛍光体は、幅広い発光装置用蛍光体として好適である。また、本実施形態の蛍光体は、ＣａＡｌＳｉＮ３を代表とする従来の窒化物・酸窒化物系蛍光体と同様に、耐熱性、耐化学的安定性に優れ、また温度上昇による輝度低下が小さい特性を有する。このような特性は、特に耐久性が要求される用途に好適である。 The phosphor of this embodiment is excited by light in a wide wavelength range from ultraviolet to visible light. For example, when irradiated with blue light having a wavelength of 455 nm, it may emit orange fluorescent light with a peak wavelength of 580 to 610 nm and a broad fluorescence spectrum with a half-width of 130 to 142 nm.
Such a phosphor is suitable for use in a wide range of light emitting devices. The phosphor of this embodiment has excellent heat resistance and chemical stability, and exhibits little decrease in luminance due to temperature rise, similar to conventional nitride/oxynitride phosphors such as CaAlSiN3 . Such characteristics are particularly suitable for applications requiring durability.
（拡散反射率）
　別観点として、本実施形態の蛍光体の、波長７００ｎｍの光に対する拡散反射率Ｘ１は、好ましくは８９％以上９８％以下、より好ましくは９１％以上９８％以下、特に好ましくは９２％以上９８％以下である。Ｘ１がこのような数値範囲内にあることで、発光強度がより高まる傾向がある。 (Diffuse Reflectance)
From another perspective, the diffuse reflectance X1 of the phosphor of this embodiment for light with a wavelength of 700 nm is preferably 89% or more and 98% or less, more preferably 91% or more and 98% or less, and particularly preferably 92% or more and 98% or less. When X1 is within such a numerical range, the luminous intensity tends to be increased.
　さらに別観点として、本実施形態の蛍光体の、蛍光ピーク波長の光に対する拡散反射率Ｘ２は、好ましくは８８％以上９７％以下、より好ましくは９０％以上９７％以下、特に好ましくは９１％以上９７％以下である。Ｘ２がこのような数値範囲内にあることで、発光強度がより高まる傾向がある。 From another perspective, the diffuse reflectance X2 of the phosphor of this embodiment for light of the fluorescent peak wavelength is preferably 88% or more and 97% or less, more preferably 90% or more and 97% or less, and particularly preferably 91% or more and 97% or less. When X2 is within such a numerical range, the luminous intensity tends to be increased.
　さらに別観点として、Ｘ２とＸ１の差（Ｘ２－Ｘ１）は、好ましくは３．０％以下、さらに好ましくは２．０％以下、特に好ましくは０．１％以上１．８％以下である。これにより、蛍光体の特性がさらに向上する。 From another perspective, the difference between X2 and X1 (X2-X1) is preferably 3.0% or less, more preferably 2.0% or less, and particularly preferably 0.1% to 1.8%. This further improves the properties of the phosphor.
　さらに別観点として、波長８００ｎｍの光に対する拡散反射率をＸ３としたとき、Ｘ３とＸ１の差（Ｘ３－Ｘ１）は、好ましくは０．１％以上１．４％、さらに好ましくは０．１％以上１．０％以下、特に好ましくは０．１％以上０．８％以下である。これにより、蛍光体の特性がさらに向上する。 From another perspective, when the diffuse reflectance for light with a wavelength of 800 nm is X3, the difference between X3 and X1 (X3-X1) is preferably 0.1% to 1.4%, more preferably 0.1% to 1.0%, and particularly preferably 0.1% to 0.8%. This further improves the properties of the phosphor.
（粒径分布）
　本実施形態の蛍光体に含まれる粒子（蛍光体粒子）の粒径分布を適切に設計することで、量子効率をより高めたり、諸性能のバランスを高めたりすることができる場合がある。
　具体的には、本実施形態の蛍光体の、レーザー回折散乱法で測定される体積基準累積５０％径Ｄ５０（いわゆるメジアン径）は、好ましくは８μｍ以上２５μｍ以下、より好ましくは１０μｍ以上２０μｍ以下、さらに好ましくは１２μｍ以上２０μｍ以下である。 (Particle Size Distribution)
By appropriately designing the particle size distribution of the particles (phosphor particles) contained in the phosphor of this embodiment, it may be possible to further increase the quantum efficiency and improve the balance of various performances.
Specifically, the volume-based cumulative 50% diameter D50 (so-called median diameter) of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 8 μm or more and 25 μm or less, more preferably 10 μm or more and 20 μm or less, and even more preferably 12 μm or more and 20 μm or less.
　別観点として、本実施形態の蛍光体の、レーザー回折散乱法で測定される体積基準累積１０％径Ｄ１０は、好ましくは２μｍ以上１５μｍ以下、より好ましくは５μｍ以上１２μｍ以下である。Ｄ１０が比較的大きな値であることは、蛍光体中の微粉（青色光の変換効率を下げる傾向がある、微細すぎる蛍光体粒子）の量が比較的少ないことに対応する。よって、Ｄ１０がある程度大きな値であることにより、青色光の変換効率がより高まる傾向がある。 From another perspective, the volume-based cumulative 10% diameter D10 of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 2 μm or more and 15 μm or less, more preferably 5 μm or more and 12 μm or less. A relatively large value of D10 corresponds to a relatively small amount of fine powder (too fine phosphor particles that tend to reduce the blue light conversion efficiency) in the phosphor. Therefore, a relatively large value of D10 tends to increase the blue light conversion efficiency.
　さらに別観点として、本実施形態の蛍光体の、レーザー回折散乱法で測定される体積基準累積９０％径Ｄ９０は、好ましくは１５μｍ以上５０μｍ以下、より好ましくは１８μｍ以上４０μｍ以下である。Ｄ９０が大きすぎないということは、蛍光体中の粗大粒子の量が少ないことに対応する。Ｄ９０が大きすぎない蛍光体は、発光装置の色度バラツキの低減に有効である。
（光吸収率）
　別観点として、本実施形態の蛍光体の、波長７００ｎｍにおける光吸収率Ａ７００は、好ましくは１％以上１０％以下、さらに好ましくは２％以上９％以下、特に好ましくは３％以上９％以下である。これにより、内部量子効率を高められる。 From another viewpoint, the volume-based cumulative 90% diameter D90 of the phosphor of this embodiment measured by a laser diffraction scattering method is preferably 15 μm or more and 50 μm or less, more preferably 18 μm or more and 40 μm or less. A D90 that is not too large corresponds to a small amount of coarse particles in the phosphor. A phosphor with a D90 that is not too large is effective in reducing chromaticity variation of a light-emitting device.
(Light Absorption Rate)
From another perspective, the light absorptance A 700 of the phosphor of this embodiment at a wavelength of 700 nm is preferably 1% or more and 10% or less, more preferably 2% or more and 9% or less, and particularly preferably 3% or more and 9% or less, thereby improving the internal quantum efficiency.
　さらに別観点として、本実施形態の蛍光体の、波長６００ｎｍにおける光吸収率Ａ６００の値は、好ましくは１％以上１３％以下、より好ましくは２％以上１２％以下、さらに好ましくは３％以上１１％以下である。Ａ６００が大きすぎないことで、蛍光特性がより一層向上すると考えられる。 From another viewpoint, the light absorptance A 600 of the phosphor of this embodiment at a wavelength of 600 nm is preferably 1% or more and 13% or less, more preferably 2% or more and 12% or less, and even more preferably 3% or more and 11% or less. It is considered that the fluorescent properties are further improved when A 600 is not too large.
　別観点として、本実施形態の蛍光体の、４５５ｎｍの励起光に対する内部量子効率の値は、好ましくは８０％以上である。
　さらに別観点として、本実施形態の蛍光体の、４５５ｎｍの励起光に対する外部量子効率の値は、好ましくは７０％以上である。 From another perspective, the internal quantum efficiency value of the phosphor of this embodiment with respect to excitation light of 455 nm is preferably 80% or more.
From another viewpoint, the external quantum efficiency value of the phosphor of this embodiment with respect to excitation light of 455 nm is preferably 70% or more.
（製造方法）
　本実施形態の蛍光体は、例えば、以下の（１）～（４）を含む一連の工程により製造可能である。蛍光体表面における表面変質部の形成を適切に調整する観点で、蛍光体の製造工程は、（４）アニール処理工程を含むことが好ましい。
（１）原料混合粉の調製工程
（２）焼成工程
（３）焼成物の粉砕工程
（４）アニール処理工程 (Production method)
The phosphor of this embodiment can be manufactured, for example, by a series of steps including the following (1) to (4). From the viewpoint of appropriately controlling the formation of the surface-altered portion on the phosphor surface, the manufacturing process of the phosphor preferably includes an annealing treatment step (4).
(1) Preparation of raw material powder mixture (2) Firing (3) Crushing the fired product (4) Annealing
　以下、（１）～（４）について具体的に説明する。 The following provides a detailed explanation of (1) to (4).
（１）原料混合粉の調製工程
　原料混合粉の調製工程においては、通常、適当な原料粉末を混合して、原料混合粉を得る。
　原料粉末としては、構成元素の窒化物、即ち窒化ケイ素、窒化アルミニウム、窒化リチウム、窒化セリウム、アルカリ土類元素の窒化物（例えば窒化カルシウム）などが好適に使用される。一般的に、窒化物粉末は空気中では不安定であり、粒子表面が酸化物層で覆われており、窒化物原料を使用した場合でも、結果的に、ある程度の酸化物が原料に含まれている。蛍光体のＯ／Ｎ比を制御する場合、これらを考慮するとともに、酸素が不足する場合は、窒化物の一部を酸化物（加熱処理により酸化物になる化合物を含む）としてもよい。酸化物の例としては、酸化セリウムなどを挙げることができる。 (1) Step of Preparing Raw Material Mixture Powder In the step of preparing the raw material mixture powder, usually, appropriate raw material powders are mixed to obtain the raw material mixture powder.
As the raw material powder, nitrides of the constituent elements, i.e., silicon nitride, aluminum nitride, lithium nitride, cerium nitride, and nitrides of alkaline earth elements (e.g., calcium nitride) are preferably used. In general, nitride powders are unstable in air, and the particle surfaces are covered with an oxide layer, so that even when a nitride raw material is used, a certain amount of oxide is ultimately contained in the raw material. When controlling the O/N ratio of the phosphor, these factors should be taken into consideration, and if there is a shortage of oxygen, a part of the nitride may be made into an oxide (including a compound that becomes an oxide by heat treatment). An example of an oxide is cerium oxide.
　原料粉末のうち、リチウム化合物は加熱による揮発が顕著であり、焼成条件によってはほとんどが揮発してしまうことがある。そこで、リチウム化合物の配合量は、焼成条件に応じて、焼成過程の揮発量を考慮して決めることが好ましい。 Among the raw material powders, lithium compounds tend to volatilize significantly when heated, and depending on the sintering conditions, most of the compound may volatilize. Therefore, it is preferable to determine the amount of lithium compound to be mixed in accordance with the sintering conditions, taking into account the amount of volatilization during the sintering process.
　窒化物原料粉末のうち、窒化リチウム、窒化セリウム、アルカリ土類元素の窒化物は、空気中の水分と激しく反応する。よって、これらの取り扱いは不活性雰囲気で置換されたグローブボックス内で行うことが好ましい。
　作業の効率性の観点から、（ｉ）まず、空気中で取り扱い可能な窒化ケイ素、窒化アルミニウム及び各種酸化物原料粉末を所定量秤量し、予め空気中で十分に混合して予備混合粉を調製し、（ｉｉ）その後、グローブボックス内で、予備混合粉と、窒化リチウム等の水分と反応しやすい物質とを混合して、原料混合粉を調製することが好ましい。 Among the nitride raw material powders, lithium nitride, cerium nitride, and nitrides of alkaline earth elements react violently with moisture in the air, so it is preferable to handle these in a glove box substituted with an inert atmosphere.
From the viewpoint of operational efficiency, it is preferable to (i) first weigh out predetermined amounts of silicon nitride, aluminum nitride and various oxide raw material powders that can be handled in air, and thoroughly mix them in advance in air to prepare a premixed powder, and (ii) then mix the premixed powder with a substance that easily reacts with moisture, such as lithium nitride, in a glove box to prepare the raw material mixed powder.
（２）焼成工程
　焼成工程では、（１）原料混合粉の調製工程で調製した原料混合粉を、適当な容器に充填して、焼成炉などを用いて加熱する。 (2) Firing Step In the firing step, the raw material mixed powder prepared in (1) Raw Material Mixture Preparation Step is filled into an appropriate container and heated using a firing furnace or the like.
　焼成の温度は、反応を十分に進める観点と、リチウムの揮発を抑える観点から、１６００～２０００℃が好ましく、１７００～１９００℃がより好ましい。
　焼成時間は、反応を十分に進める観点と、リチウムの揮発を抑える観点から、２～２４時間が好ましく、４～１６時間がより好ましい。 The firing temperature is preferably 1600 to 2000° C., more preferably 1700 to 1900° C., from the viewpoints of sufficiently promoting the reaction and suppressing the volatilization of lithium.
The baking time is preferably from 2 to 24 hours, more preferably from 4 to 16 hours, from the viewpoint of sufficiently promoting the reaction and suppressing the volatilization of lithium.
　焼成工程は、窒素雰囲気下で行われることが好ましい。また、焼成雰囲気の圧力を適切に調整することが好ましい。具体的には、焼成雰囲気の圧力は、０．５ＭＰａ・Ｇ以上が好ましい。焼成温度が特に１８００℃以上である場合、蛍光体が分解しやすい傾向があるが、焼成雰囲気の圧力が高いことで、蛍光体の分解を抑制することができる。
　ちなみに、工業的生産性を考慮すると、焼成雰囲気の圧力は１ＭＰａ・Ｇ未満が好ましい。 The firing step is preferably carried out under a nitrogen atmosphere. It is also preferable to appropriately adjust the pressure of the firing atmosphere. Specifically, the pressure of the firing atmosphere is preferably 0.5 MPa·G or more. When the firing temperature is particularly 1800° C. or more, the phosphor tends to decompose, but by increasing the pressure of the firing atmosphere, the decomposition of the phosphor can be suppressed.
In consideration of industrial productivity, the pressure of the firing atmosphere is preferably less than 1 MPa·G.
　原料混合粉を充填する容器は、高温の窒素雰囲気下において安定で、原料混合粉やその反応生成物と反応しない材質で構成されることが好ましい。容器の材質は、好ましくは窒化ホウ素である。 The container for filling the raw material mixture powder is preferably made of a material that is stable in a high-temperature nitrogen atmosphere and does not react with the raw material mixture powder or its reaction products. The material of the container is preferably boron nitride.
（３）焼成物の粉砕工程
　（２）で得られる焼成物は、通常、塊状であるため、機械的に力を加えることである程度小さいサイズに粉砕することが好ましい。
　粉砕には、クラッシャー、乳鉢、ボールミル、振動ミル、ジェットミル、スタンプミル等の各種装置を用いることができる。これら装置のうち２つ以上を組み合わせて粉砕してもよい。後掲の実施例においては、まずスタンプミルを用いて焼成物の粗粉砕物を得、その後、その粗粉砕物を、ジェットミルを用いてより細かく粉砕している。詳細は不明であるが、このような粉砕を行うことにより、拡散反射率Ｘ１が８８％以上９９．９％以下である蛍光体を得やすい。 (3) Crushing step of the fired product Since the fired product obtained in (2) is usually in the form of lumps, it is preferable to crush it into relatively small sizes by applying a mechanical force.
For the pulverization, various devices such as a crusher, a mortar, a ball mill, a vibration mill, a jet mill, a stamp mill, etc. may be used. Two or more of these devices may be combined for pulverization. In the examples shown below, a coarsely pulverized product of the fired material is first obtained using a stamp mill, and then the coarsely pulverized product is further pulverized using a jet mill. Although the details are unclear, such pulverization makes it easy to obtain a phosphor having a diffuse reflectance X1 of 88% or more and 99.9% or less.
（４）アニール処理
　アニール処理では、所定量の蛍光体を坩堝に充填し、水素ガスを含む還元性ガス雰囲気下、焼成炉内で、所定温度で所定時間、蛍光体を加熱する。
　具体的には、アニール温度は、上記の焼成温度よりも低く、７００～１２００℃程度が好ましい。アニール時間は、アニール温度に応じて適宜設定する。
　アニール時の雰囲気は、還元性を有するものであり、例えば、窒素ガス（不活性ガス）中に４体積％程度の水素ガス（還元性ガス）を含むものが好ましい。
　蓋なしの坩堝を使用し、坩堝中の蛍光体の充填量が少ないことが好ましい。アニール処理中、混合ガス雰囲気と蛍光体の表面とを十分に接触させることが可能となる。
　アルミナ製の緻密質な坩堝を使用することが好ましい。炉内に含まれる成分と坩堝とが反応し、雰囲気環境が意図せずに変化することを抑制できる。
　詳細なメカニズムは定かではないが、還元性混合ガス雰囲気中、比較的低温にて、開放系にある蛍光体を加熱するというアニール処理により、かかる蛍光体の表面を適切に改質できると考えられる。 (4) Annealing Treatment In the annealing treatment, a predetermined amount of phosphor is placed in a crucible, and the phosphor is heated in a baking furnace in an atmosphere of reducing gas containing hydrogen gas at a predetermined temperature for a predetermined time.
Specifically, the annealing temperature is lower than the above-mentioned firing temperature, and is preferably about 700 to 1200° C. The annealing time is appropriately set according to the annealing temperature.
The atmosphere during annealing is preferably one having reducing properties, for example, one containing about 4 volume % of hydrogen gas (reducing gas) in nitrogen gas (inert gas).
It is preferable to use a crucible without a lid and to have a low loading of phosphor in the crucible, which allows for sufficient contact between the mixed gas atmosphere and the phosphor surface during the annealing process.
It is preferable to use a dense crucible made of alumina, which can prevent the components contained in the furnace from reacting with the crucible, thereby preventing unintended changes in the atmospheric environment.
Although the detailed mechanism is unclear, it is believed that the surface of such a phosphor can be appropriately modified by annealing treatment in which the phosphor is heated in an open system at a relatively low temperature in a reducing mixed gas atmosphere.
＜発光装置、画像表示装置および照明装置＞
　本実施形態の蛍光体と、発光光源とを組み合わせることで、発光装置を得ることができる。
　発光光源は、典型的には紫外線又は可視光を発光する。例えば、発光光源が青色ＬＥＤである場合、発光光源から発せられる青色光が蛍光体に当たり、そして青色光はより長波長の光に変換される。すなわち、本実施形態の蛍光体は、青色光をより長波長の光に変換する波長変換材料として使用可能である。 <Light-emitting device, image display device, and lighting device>
A light emitting device can be obtained by combining the phosphor of this embodiment with a light source.
The luminescent light source typically emits ultraviolet or visible light. For example, when the luminescent light source is a blue LED, the blue light emitted from the luminescent light source hits the phosphor, and the blue light is converted into light with a longer wavelength. That is, the phosphor of the present embodiment can be used as a wavelength conversion material that converts blue light into light with a longer wavelength.
　発光装置の具体的構成の一例を、図１を参照しつつ説明する。
　図１は、発光装置の構造の一例を示す概略断面図である。図１に示されるように、発光装置１００は、発光素子１２０（発光光源）、ヒートシンク１３０、ケース１４０、第１リードフレーム１５０、第２リードフレーム１６０、ボンディングワイヤ１７０、ボンディングワイヤ１７２および複合体４０を備える。 An example of a specific configuration of the light emitting device will be described with reference to FIG.
1 is a schematic cross-sectional view showing an example of the structure of a light emitting device. As shown in Fig. 1, the light emitting device 100 includes a light emitting element 120 (light emitting source), a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, a bonding wire 170, a bonding wire 172, and a composite body 40.
　発光素子１２０は、励起光を発する半導体素子である。半導体素子には、発光ダイオード（ＬＥＤ）および、共振器を備える発光素子（ＬＤ）のいずれも使用できる。発光素子１２０としては、たとえば、近紫外から青色光に相当する３００ｎｍ以上５００ｎｍ以下の波長の光を発生するＬＥＤチップを使用することができる。 The light-emitting element 120 is a semiconductor element that emits excitation light. The semiconductor element can be either a light-emitting diode (LED) or a light-emitting element (LD) equipped with a resonator. As the light-emitting element 120, for example, an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used.
　発光素子１２０はヒートシンク１３０上面の所定領域に実装されている。ヒートシンク１３０上に発光素子１２０を実装することにより、発光素子１２０の放熱性を高めることができる。なお、ヒートシンク１３０に代えて、パッケージ用基板を用いてもよい。
　発光素子１２０の上面側に配設された一方の電極（図示せず）が、金線などのボンディングワイヤ１７０を介して第１リードフレーム１５０の表面と接続されている。また、発光素子１２０の上面に形成されている他方の電極（図示せず）は、金線などのボンディングワイヤ１７２を介して第２リードフレーム１６０の表面と接続されている。 The light emitting element 120 is mounted in a predetermined region on the upper surface of the heat sink 130. By mounting the light emitting element 120 on the heat sink 130, it is possible to improve the heat dissipation properties of the light emitting element 120. Note that a packaging substrate may be used instead of the heat sink 130.
One electrode (not shown) disposed on the upper surface side of the light emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. The other electrode (not shown) formed on the upper surface of the light emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.
　ケース１４０には、底面から上方に向かって孔径が徐々に拡大する略漏斗形状の凹部が形成されている。発光素子１２０は、上記凹部の底面に設けられている。発光素子１２０を取り囲む凹部の壁面は反射板の役目を担う。 The case 140 has a generally funnel-shaped recess whose diameter gradually increases from the bottom surface upward. The light-emitting element 120 is provided on the bottom surface of the recess. The wall surface of the recess surrounding the light-emitting element 120 acts as a reflector.
　複合体４０は、ケース１４０によって壁面が形成される上記凹部に充填されている。複合体４０は、発光素子１２０から発せられる励起光をより長波長の光に変換する波長変換部材である。
　複合体４０は、樹脂などの封止材３０中に、少なくとも本実施形態の蛍光体が分散したものである。より品質の高い白色光を得るため、封止材３０は、本実施形態の蛍光体だけでなく、その他の蛍光体を含んでもよい。
　発光装置１００は、発光素子１２０の光と、発光素子１２０から発せられる光を吸収して励起される蛍光体粒子１から発せられる光との混合色を発する。発光装置１００は、発光素子１２０の光と蛍光体粒子１から発生する光との混色により白色を発光することが好ましい。 The composite 40 is filled in the recess whose wall is formed by the case 140. The composite 40 is a wavelength conversion member that converts the excitation light emitted from the light emitting element 120 into light with a longer wavelength.
The composite 40 is obtained by dispersing at least the phosphor of this embodiment in an encapsulant 30 such as a resin. In order to obtain white light of higher quality, the encapsulant 30 may contain not only the phosphor of this embodiment but also other phosphors.
The light emitting device 100 emits a mixed color of light from the light emitting element 120 and light emitted from the phosphor particles 1 that are excited by absorbing the light emitted from the light emitting element 120. It is preferable that the light emitting device 100 emits white light by mixing the light from the light emitting element 120 and the light generated from the phosphor particles 1.
　ちなみに、図１では、表面実装型の発光装置が例示されているが、発光装置は表面実装型に限定されず、砲弾型やＣＯＢ（チップオンボード）型、ＣＳＰ（チップスケールパッケージ）型であってもよい。 Incidentally, while FIG. 1 shows a surface-mounted light-emitting device as an example, the light-emitting device is not limited to the surface-mounted type, and may be a bullet type, a COB (chip-on-board) type, or a CSP (chip-scale package) type.
　発光装置の使い道としては、ディスプレイなどの画像表示装置や、照明装置が挙げられる。例えば、発光装置１００をバックライトとして用いて、液晶ディスプレイを製造することができる。また、発光装置１００を１つまたは複数個用いて、適切な配線を施すなどすることで、照明装置を製造することもできる。 The light-emitting device can be used in image display devices such as displays, and lighting devices. For example, a liquid crystal display can be manufactured using the light-emitting device 100 as a backlight. A lighting device can also be manufactured using one or more light-emitting devices 100 with appropriate wiring.
　以上、本発明の実施形態について述べたが、これらは本発明の例示であり、上記以外の様々な構成を採用することができる。また、本発明は上述の実施形態に限定されるものではなく、本発明の目的を達成できる範囲での変形、改良等は本発明に含まれる。 The above describes the embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention.
　以下、本発明について実施例を参照して詳細に説明するが、本発明は、これらの実施例の記載に何ら限定されるものではない。
＜蛍光体粉末の製造＞
（比較例１）
（１）原料混合粉の調製
　まず、予備混合を行った。具体的には、表１に記載の原料のうち、Ｓｉ３Ｎ４（宇部興産社製、Ｅ１０グレード）、ＡｌＮ（トクヤマ社製、Ｅグレード）およびＣｅＯ２（信越化学工業社製、Ｃグレード）を、小型Ｖ型混合機を用いて３０分間混合（ドライブレンド）し、その後、目開き１５０μｍのナイロン製の篩で通篩した。これにより予備混合粉を得た。
　次に、窒素雰囲気のグローブボックス内で、予備混合粉に、表１に記載の原料の残り（Ｃａ３Ｎ２（太平洋セメント社製のＣａ３Ｎ２）およびＬｉ３Ｎ（Ｍａｔｅｒｉｏｎ社製のＬｉ３Ｎ））を加え、十分にドライブレンドし、その後、目開き５００μｍの篩で通篩した。これにより原料混合粉を得た。 The present invention will be described in detail below with reference to examples, but the present invention is not limited to the description of these examples.
<Production of phosphor powder>
(Comparative Example 1)
(1) Preparation of raw material mixed powder First, premixing was performed. Specifically, among the raw materials shown in Table 1, Si 3 N 4 (Ube Industries, E10 grade), AlN (Tokuyama, E grade), and CeO 2 (Shin-Etsu Chemical, C grade) were mixed (dry blended) for 30 minutes using a small V-type mixer, and then sieved through a nylon sieve with 150 μm openings. This produced a premixed powder.
Next, in a glove box with a nitrogen atmosphere, the remaining raw materials listed in Table 1 ( Ca3N2 ( Ca3N2 manufactured by Taiheiyo Cement Corporation) and Li3N ( Li3N manufactured by Materion Corporation)) were added to the premixed powder, thoroughly dry-blended, and then sieved through a sieve with 500 μm openings. This produced a raw material mixed powder.
（２）焼成
　原料混合粉を窒化ホウ素製の容器に充填した。この容器を炉に入れ、原料混合粉を、０．７２ＭＰａ・ＧのＮ２雰囲気下、１８００℃で８時間焼成した。 (2) Sintering The raw material mixed powder was filled into a boron nitride container. The container was placed in a furnace, and the raw material mixed powder was sintered at 1800°C for 8 hours under a N2 atmosphere of 0.72 MPa·G.
（３）焼成物の粉砕
　（２）で得られた焼成物を、スタンプミルを用いて粉砕した。スタンプミルによる粉砕は、目開き２５０μｍの振動篩の通過率が９０％を超えるまで繰り返した。
　スタンプミルによる粉砕を経た焼成物を、さらに、ジェットミル（日本ニューマチック工業製、ＰＪＭ－８０ＳＰ）を用いて粉砕した。粉砕条件は、試料供給速度：５０ｇ／ｍｉｎ、粉砕エア圧：０．３ＭＰａとした。
　以上により、蛍光体粉末を得た。 (3) Pulverization of the fired product The fired product obtained in (2) was pulverized using a stamp mill. The pulverization using the stamp mill was repeated until the passing rate of the fired product through a vibrating sieve with an opening of 250 μm exceeded 90%.
The fired product that had been pulverized by the stamp mill was further pulverized by a jet mill (PJM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) under the following pulverization conditions: sample supply rate: 50 g/min, pulverization air pressure: 0.3 MPa.
In this manner, a phosphor powder was obtained.
（実施例１、２および比較例２）
　比較例１で得られた蛍光体粉末に、表１に記載の条件のアニール処理を施して、蛍光体粉末を得た。
　かかるアニール処理は、表１に記載の条件に従って、所定サンプル量の蛍光体粉末をアルミナ製坩堝（蓋なし）に充填し、表１に記載の所定雰囲気下、所定焼成炉内で、所定の最大温度（ただし、室温から最大温度まで昇温速度３℃／ｍｉｎで昇温）で所定時間、坩堝に充填した蛍光体粉末を加熱した。加熱後、最大温度から５００℃まで約１．３℃／ｍｉｎで冷却、５００℃から３００℃まで約１．１／℃ｍｉｎで冷却、３００℃以降は炉内で冷却した。
　なお、実施例２のアニール処理には、実施例１と比べて、サンプル量を増大させ、加熱温度を高く設定した。比較例２のアニール処理には、Ｈ２ガスを含まず、Ｎ２ガスが充填した雰囲気を採用した。実施例１～３では、Ｎ２ガスに対して所定量のＨ２ガスを混合した混合ガスを大気圧フローにて導入し、雰囲気に充填させた。 (Examples 1 and 2 and Comparative Example 2)
The phosphor powder obtained in Comparative Example 1 was subjected to an annealing treatment under the conditions shown in Table 1 to obtain a phosphor powder.
The annealing treatment was carried out by filling a predetermined sample amount of phosphor powder into an alumina crucible (without a lid) according to the conditions shown in Table 1, and heating the phosphor powder filled in the crucible at a predetermined maximum temperature (wherein the temperature was increased from room temperature to the maximum temperature at a rate of 3°C/min) for a predetermined time in a predetermined firing furnace under a predetermined atmosphere shown in Table 1. After heating, the phosphor powder was cooled from the maximum temperature to 500°C at about 1.3°C/min, cooled from 500°C to 300°C at about 1.1/°Cmin, and cooled in the furnace after 300°C.
In the annealing treatment of Example 2, the amount of sample was increased and the heating temperature was set higher than in Example 1. In the annealing treatment of Comparative Example 2, an atmosphere filled with N2 gas without containing H2 gas was used. In Examples 1 to 3, a mixed gas of N2 gas and a predetermined amount of H2 gas was introduced at atmospheric pressure flow to fill the atmosphere.
（実施例３）
　比較例３で得られた蛍光体粉末に、表１に記載の条件のアニール処理を施して、蛍光体粉末を得た。 Example 3
The phosphor powder obtained in Comparative Example 3 was subjected to an annealing treatment under the conditions shown in Table 1 to obtain a phosphor powder.
（比較例２）
　β型サイアロン蛍光体粉末（デンカ社製、グレード名：ＧＲ－ＭＷ５４０Ｋ８ＳＤ）に、表１に記載の条件のアニール処理を施して、β型サイアロンの蛍光体粉末（アニール処理後）を得た。 (Comparative Example 2)
A β-type sialon phosphor powder (manufactured by Denka, grade name: GR-MW540K8SD) was subjected to annealing treatment under the conditions shown in Table 1 to obtain a β-type sialon phosphor powder (after annealing treatment).
＜化学組成／結晶構造の確認＞
　一部の蛍光体粉末ついて、以下のように組成を分析した。
　Ｃａ、Ｌｉ、Ｃｅ、ＳｉおよびＡｌの量：アルカリ融解法により蛍光体粉末を溶解させ、その後、ＩＣＰ発光分光分析装置（Ａｇｉｌｅｎｔ社製５１１０ＶＤＶ）により測定した。
　ＯおよびＮの量：酸素窒素分析装置（ＨＯＲＩＢＡ社製、ＥＭＧＡ－９２０）により測定した。
　測定結果に基づき、一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙにおけるｘ、ｙ、Ｓｉ／Ａｌ原子比、Ｏ／Ｎ原子比、ＭのＬｉ比率、および、ＭのＣｅ比率を求めた。 <Confirmation of chemical composition/crystal structure>
The composition of some of the phosphor powders was analyzed as follows.
Amounts of Ca, Li, Ce, Si and Al: The phosphor powder was dissolved by an alkali fusion method, and then the amounts were measured using an ICP emission spectrometer (5110VDV manufactured by Agilent).
Amounts of O and N: Measured with an oxygen/nitrogen analyzer (HORIBA, EMGA-920).
Based on the measurement results, x, y, the Si/Al atomic ratio, the O/N atomic ratio, the Li ratio of M, and the Ce ratio of M in the general formula Mx (Si,Al) 2 ( N,O)3±y were determined.
　実施例１～３の蛍光体に対しては、Ｘ線回折装置（株式会社リガク社製ＵｌｔｉｍａＩＶ－Ｎ）を用い、Ｃｕ－Ｋα線による粉末Ｘ線回折（ＸＲＤ）測定を行った。得られたＸＲＤパターンの解析から、斜方晶系で格子定数ａ＝０．９４８６ｎｍ、ｂ＝０．５５８６ｎｍ、ｃ＝０．４９３３ｎｍの結晶を主相の存在が確認された。 The phosphors of Examples 1 to 3 were subjected to powder X-ray diffraction (XRD) measurement using Cu-Kα radiation using an X-ray diffractometer (Ultima IV-N manufactured by Rigaku Corporation). Analysis of the obtained XRD pattern confirmed the presence of a main phase of crystals in the orthorhombic system with lattice constants a = 0.9486 nm, b = 0.5586 nm, and c = 0.4933 nm.
＜ＳＥＭ写真＞
　得られた実施例１～３、および比較例１～３の蛍光体粉末の表面について、走査電子顕微鏡（電子線の加速電圧：３ｋＶ、倍率：２０００及び５０００倍）を用いてＳＥＭ写真を撮影した。
　図２は実施例１、図３は実施例２、図４は実施例３の蛍光体粉末を示す。
　図５は比施例１、図６は比施例２、図７は比施例３の蛍光体粉末を示す。 <SEM photo>
The surfaces of the obtained phosphor powders of Examples 1 to 3 and Comparative Examples 1 to 3 were photographed with SEM photographs using a scanning electron microscope (electron beam accelerating voltage: 3 kV, magnifications: 2000 and 5000 times).
FIG. 2 shows the phosphor powder of Example 1, FIG. 3 shows the phosphor powder of Example 2, and FIG.
5 shows the phosphor powder of Comparative Example 1, FIG. 6 shows the phosphor powder of Comparative Example 2, and FIG.
　比較例１～３では、上記のＳＥＭ写真により、蛍光体粒子の表面の大部分に平滑面が露出しており、その平滑面上に蛍光体が破砕して形成された破砕片が付着しているのが確認された。また、比較例１～３の蛍光体粉末を水洗することにより、上記の破砕片が蛍光体粒子表面からある程度除去されることが確認された。 In Comparative Examples 1 to 3, the SEM photographs above confirmed that most of the surface of the phosphor particles was exposed as a smooth surface, with fragments formed by crushing the phosphor adhering to the smooth surface. It was also confirmed that washing the phosphor powders of Comparative Examples 1 to 3 with water removed the above-mentioned fragments to a certain extent from the phosphor particle surface.
　一方、実施例１～３では、上記のＳＥＭ写真により、蛍光体粒子の表面に、複数の隆起部分が存在することが確認された。隆起部分には、上記の破砕片とは異なり破砕面がなく、扁平構造を有するものがいくつか確認された。
　また、上記の蛍光体粉末の化学組成分析の結果、酸素元素量（重量％）において、実施例１～２が比較例１よりも高く、実施例３が比較例３よりも高い結果を示した。実施例１～３の蛍光体粉末を水洗しても、上記隆起部分は、水洗後の蛍光体粒子の表面からほとんど除去されないことが確認された。このような結果から、蛍光体粒子の表面の一部に形成された隆起部分は、上記のアニール処理により蛍光体の表面が変質して形成された表面変質部であると判断した。 On the other hand, in Examples 1 to 3, the above SEM photographs confirmed that there were multiple raised parts on the surface of the phosphor particles. Unlike the above-mentioned crushed pieces, the raised parts did not have a crushed surface, and some of them had a flat structure.
Furthermore, as a result of chemical composition analysis of the above phosphor powder, the oxygen element amount (wt%) was higher in Examples 1 and 2 than in Comparative Example 1, and higher in Example 3 than in Comparative Example 3. It was confirmed that even if the phosphor powders of Examples 1 to 3 were washed with water, the above-mentioned raised portions were hardly removed from the surfaces of the phosphor particles after washing with water. From these results, it was determined that the raised portions formed on part of the surfaces of the phosphor particles were surface altered parts formed by the surface of the phosphor being altered by the above-mentioned annealing treatment.
＜拡散反射率の測定＞
　拡散反射率は、日本分光社製紫外可視分光光度計（Ｖ－５５０）に積分球装置（ＩＳＶ－４６９）を取り付けた装置を用いて測定した。測定に際しては、標準反射板（スペクトラロン）でベースライン補正を行った。
　蛍光体粉末を充填した固体試料ホルダーを装置内の所定の位置に取り付けて、５００～８５０ｎｍの波長範囲で拡散反射スペクトルを測定し、波長６００ｎｍの光、波長７００ｎｍの光、波長８００ｎｍの光、および、蛍光体粉末の蛍光ピーク波長の光（後述）に対する拡散反射率を求めた。 <Measurement of diffuse reflectance>
The diffuse reflectance was measured using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). During the measurement, baseline correction was performed using a standard reflector (Spectralon).
The solid sample holder filled with the phosphor powder was attached to a predetermined position in the apparatus, and the diffuse reflectance spectrum was measured in the wavelength range of 500 to 850 nm, and the diffuse reflectance was determined for light with wavelengths of 600 nm, 700 nm, and 800 nm, as well as for light with the fluorescent peak wavelength of the phosphor powder (described below).
＜粒径分布の測定＞
　粒径分布は、ＬＳ１３　３２０（ベックマン・コールター株式会社製）を用い、ＪＩＳ　Ｒ　１６２９：１９９７に準拠したレーザー回折散乱法により測定した。測定溶媒には水を使用した。
　具体的な手順として、まず、分散剤としてヘキサメタリン酸ナトリウムを０．０５質量％加えた水溶液に少量の蛍光体粉末を投入した。次に、ホーン式の超音波ホモジナイザー（出力３００Ｗ、ホーン径２６ｍｍ）で分散処理を行って分散液を作製した。この分散液を測定溶媒に適量添加して粒径分布を測定した。得られた累積体積頻度分布曲線から、１０％体積径（Ｄ１０）、５０％体積径（Ｄ５０）および９０％体積径（Ｄ９０）を求めた。 <Measurement of particle size distribution>
The particle size distribution was measured by a laser diffraction scattering method in accordance with JIS R 1629: 1997 using an LS13 320 (manufactured by Beckman Coulter, Inc.) Water was used as the measurement solvent.
Specifically, a small amount of phosphor powder was added to an aqueous solution containing 0.05% by mass of sodium hexametaphosphate as a dispersant. A dispersion was then prepared by dispersing the powder using a horn-type ultrasonic homogenizer (output: 300 W, horn diameter: 26 mm). An appropriate amount of this dispersion was added to a measurement solvent to measure the particle size distribution. From the obtained cumulative volume frequency distribution curve, the 10% volume diameter (D 10 ), 50% volume diameter (D 50 ), and 90% volume diameter (D 90 ) were obtained.
＜蛍光スペクトルの測定＞
　ローダミンＢと副標準光源で補正を行った分光蛍光光度計（日立ハイテクサイエンス社製、Ｆ－７０００）を用いて、蛍光体粉末の蛍光スペクトルを測定した。具体的には、波長４５５ｎｍの単色光で蛍光体粉末を励起させることにより発せられる蛍光のスペクトルを測定し、蛍光ピーク波長（ｎｍ）および蛍光ピークにおける半値幅（ｎｍ）を求めた。 <Measurement of fluorescence spectrum>
The fluorescence spectrum of the phosphor powder was measured using a spectrofluorophotometer (Hitachi High-Tech Science Corporation, F-7000) corrected with Rhodamine B and a secondary standard light source. Specifically, the spectrum of the fluorescence emitted by exciting the phosphor powder with monochromatic light of a wavelength of 455 nm was measured, and the fluorescence peak wavelength (nm) and the half-width (nm) at the fluorescence peak were obtained.
＜内部量子効率および外部量子効率の測定＞
　分光光度計（大塚電子株式会社製ＭＣＰＤ－７０００）を用い、各蛍光体粉末の内部量子効率および外部量子効率を、以下の手順で求めた。
（１）蛍光体粉末を、凹型セルの窪み部分に、表面が平滑になるように充填した。この凹型セルを、積分球内の所定の位置（試料部）に取り付けた。この積分球に、発光光源（Ｘｅランプ）から４５５ｎｍの波長に分光した単色光を、光ファイバーを用いて導入した。この単色光（励起光）を、凹型セルの窪み部分に充填された蛍光体粉末に照射し、蛍光スペクトルを測定した。得られたスペクトルデータから、励起反射光フォトン数（Ｑｒｅｆ）及び蛍光フォトン数（Ｑｅｍ）を算出した。励起反射光フォトン数は４５０ｎｍ以上４６５ｎｍ以下の波長範囲で蛍光フォトン数は、４６５ｎｍ以上８００ｎｍ以下の範囲で算出した。
（２）また、試料部に、凹型セルの代わりに、反射率が９９％の標準反射板（Ｌａｂｓｐｈｅｒｅ社製スペクトラロン）を取り付けて、波長４５５ｎｍの励起光のスペクトルを測定した。そして、４５０ｎｍ以上４６５ｎｍ以下の波長範囲のスペクトルから励起光フォトン数（Ｑｅｘ）を算出した。
（３）上記（１）および（２）で求めたＱｒｅｆ、ＱｅｍおよびＱｅｘから、以下式に基づき内部量子効率および外部量子効率を算出した。
内部量子効率＝（Ｑｅｍ／（Ｑｅｘ－Ｑｒｅｆ））×１００
外部量子効率＝（Ｑｅｍ／Ｑｅｘ）×１００ <Measurement of internal quantum efficiency and external quantum efficiency>
The internal quantum efficiency and external quantum efficiency of each phosphor powder were determined using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.) according to the following procedure.
(1) The phosphor powder was filled into the recess of the concave cell so that the surface was smooth. This concave cell was attached to a predetermined position (sample part) in the integrating sphere. Monochromatic light, which was split into a wavelength of 455 nm from a light emission source (Xe lamp), was introduced into the integrating sphere using an optical fiber. This monochromatic light (excitation light) was irradiated onto the phosphor powder filled in the recess of the concave cell, and the fluorescence spectrum was measured. From the obtained spectral data, the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated. The number of excitation reflected light photons was calculated in the wavelength range of 450 nm to 465 nm, and the number of fluorescence photons was calculated in the wavelength range of 465 nm to 800 nm.
(2) In addition, instead of the concave cell, a standard reflector with a reflectance of 99% (Spectralon manufactured by Labsphere) was attached to the sample section to measure the spectrum of excitation light with a wavelength of 455 nm. The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 nm to 465 nm.
(3) The internal quantum efficiency and the external quantum efficiency were calculated from Qref, Qem, and Qex obtained in (1) and (2) above according to the following formula.
Internal quantum efficiency = (Qem / (Qex - Qref)) x 100
External quantum efficiency = (Qem/Qex) x 100
＜波長６００ｎｍにおける光吸収率の測定＞
　積分球を備える分光光度計（大塚電子株式会社製ＭＣＰＤ－７０００）を用い、各蛍光体粉末の波長６００ｎｍにおける光吸収率を、以下の手順で求めた。
（１）積分球内の所定の位置（試料部）に、反射率が９９％の標準反射板（Ｌａｂｓｐｈｅｒｅ社製スペクトラロン）を取り付けて、発光光源（Ｘｅランプ）から６００ｎｍの波長に分光した単色光を標準反射板に照射した。そして、波長５９５～６１０ｎｍの範囲で励起光のフォトン数（Ｑｅｘ）を算出した。
（２）標準反射板を測定サンプルに替えた以外は（１）と同様にして、サンプルの励起反射フォトン数（Ｑｒｅｆ）を算出した。測定サンプルとしては、蛍光体粉末を、凹型セルの窪み部分に、表面が平滑になるように充填したものを用いた。
（３）式（Ｑｅｘ－Ｑｒｅｆ）／Ｑｅｘにより、波長６００ｎｍにおける光吸収率Ａ６００を算出した。 <Measurement of light absorptance at a wavelength of 600 nm>
Using a spectrophotometer equipped with an integrating sphere (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.), the light absorptance of each phosphor powder at a wavelength of 600 nm was determined according to the following procedure.
(1) A standard reflector (Spectralon, manufactured by Labsphere) with a reflectance of 99% was attached to a predetermined position (sample portion) in the integrating sphere, and monochromatic light separated to a wavelength of 600 nm from a light emission source (Xe lamp) was irradiated onto the standard reflector. Then, the number of photons (Qex) of the excitation light was calculated in the wavelength range of 595 to 610 nm.
(2) The number of excited reflected photons (Qref) of the sample was calculated in the same manner as in (1) except that the standard reflector was replaced with a measurement sample. The measurement sample was a phosphor powder filled in the recess of a concave cell so that the surface was smooth.
The light absorptance A 600 at a wavelength of 600 nm was calculated using the formula (Qex-Qref)/Qex (3).
＜波長７００ｎｍにおける光吸収率の測定＞
　積分球を備える分光光度計（大塚電子株式会社製ＭＣＰＤ－７０００）を用い、各蛍光体粉末の波長７００ｎｍにおける光吸収率を、以下の手順で求めた。
（１）積分球内の所定の位置（試料部）に、反射率が９９％の標準反射板（Ｌａｂｓｐｈｅｒｅ社製スペクトラロン）を取り付けて、発光光源（Ｘｅランプ）から７００ｎｍの波長に分光した単色光を標準反射板に照射した。そして、波長６９５～７１０ｎｍの範囲で励起光のフォトン数（Ｑｅｘ）を算出した。
（２）標準反射板を測定サンプルに替えた以外は（１）と同様にして、サンプルの励起反射フォトン数（Ｑｒｅｆ）を算出した。測定サンプルとしては、蛍光体粉末を、凹型セルの窪み部分に、表面が平滑になるように充填したものを用いた。
（３）式（Ｑｅｘ－Ｑｒｅｆ）／Ｑｅｘにより、波長７００ｎｍにおける光吸収率Ａ７００を算出した。 <Measurement of light absorptance at a wavelength of 700 nm>
Using a spectrophotometer equipped with an integrating sphere (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.), the light absorptance of each phosphor powder at a wavelength of 700 nm was determined according to the following procedure.
(1) A standard reflector (Spectralon, manufactured by Labsphere) with a reflectance of 99% was attached to a predetermined position (sample portion) in the integrating sphere, and monochromatic light having a wavelength of 700 nm was irradiated onto the standard reflector from a light emission source (Xe lamp). Then, the number of photons (Qex) of the excitation light was calculated in the wavelength range of 695 to 710 nm.
(2) The number of excited reflected photons (Qref) of the sample was calculated in the same manner as in (1) except that the standard reflector was replaced with a measurement sample. The measurement sample was a phosphor powder filled in the recess of a concave cell so that the surface was smooth.
The light absorptance A 700 at a wavelength of 700 nm was calculated using the formula (Qex-Qref)/Qex (3).
　各種情報をまとめて表１に示す。 Various pieces of information are summarized in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示されるとおり、実施例１～３の一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙで表される蛍光体粉末は、比較例１～３と比べて、内部量子効率や６００ｎｍにおける拡散反射率等の発光特性が優れる結果を示した。
　なお、比較例３のβ型サイアロンの蛍光体は、実施例１と同様のアニール処理を施すと、アニール処理前と比べて、内部量子効率や６００ｎｍにおける拡散反射率が大きく低下する結果を示した。 As shown in Table 1, the phosphor powders of Examples 1 to 3 represented by the general formula M x (Si,Al) 2 (N,O) 3±y showed superior luminescence characteristics such as internal quantum efficiency and diffuse reflectance at 600 nm compared to Comparative Examples 1 to 3.
Incidentally, when the β-sialon phosphor of Comparative Example 3 was subjected to the same annealing treatment as in Example 1, the internal quantum efficiency and the diffuse reflectance at 600 nm were significantly decreased compared to before the annealing treatment.
　この出願は、２０２２年１１月１１日に出願された日本出願特願２０２２－１８１２６０号を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2022-181260, filed on November 11, 2022, the entire disclosure of which is incorporated herein by reference.
１　蛍光体粒子
３０　封止材
４０　複合体
１００　発光装置
１２０　発光素子
１３０　ヒートシンク
１４０　ケース
１５０　第１リードフレーム
１６０　第２リードフレーム
１７０　ボンディングワイヤ
１７２　ボンディングワイヤ
　 Reference Signs List 1 Phosphor particle 30 Sealant 40 Composite 100 Light emitting device 120 Light emitting element 130 Heat sink 140 Case 150 First lead frame 160 Second lead frame 170 Bonding wire 172 Bonding wire

Claims (10)

  1. 　一般式Ｍｘ（Ｓｉ，Ａｌ）２（Ｎ，Ｏ）３±ｙ（ただし、ＭはＬｉ及び一種以上のアルカリ土類金属元素であり、０．５２≦ｘ≦０．９０、０≦ｙ≦０．３６）で示され、Ｍの一部がＣｅ元素で置換されている蛍光体の粒子を含む蛍光体粉末であって、
    　前記蛍光体の粒子の表面の一部が隆起している表面変質部を含む、蛍光体粉末。     A phosphor powder containing particles of a phosphor represented by a general formula Mx (Si,Al) 2 (N,O) 3±y (wherein M is Li and one or more alkaline earth metal elements, 0.52≦x≦0.90, 0≦y≦0.36), in which a part of M is substituted with a Ce element,
    The phosphor powder includes a surface alteration portion in which a part of the surface of the phosphor particle is raised.
  2. 　請求項１に記載の蛍光体粉末であって、
    　前記表面変質部が、扁平状構造を含む、蛍光体粉末。     The phosphor powder according to claim 1 ,
    The surface altered portion includes a flat structure.
  3. 　請求項１又は２に記載の蛍光体粉末であって、
    　前記表面変質部が、酸化物または水酸化物を含む、蛍光体粉末。     The phosphor powder according to claim 1 or 2,
    The phosphor powder, wherein the surface alteration portion includes an oxide or a hydroxide.
  4. 　請求項１又は２に記載の蛍光体粉末であって、
    　レーザー回折散乱法で測定される当該蛍光体粉末の体積頻度粒度分布において、小粒子側からの累積体積が５０％となる点の粒子径をＤ５０としたとき、Ｄ５０が８μｍ以上２５μｍ以下である、蛍光体粉末。     The phosphor powder according to claim 1 or 2,
    A phosphor powder, wherein when the particle diameter at the point where the cumulative volume from the small particle side is 50% in a volume frequency particle size distribution of the phosphor powder measured by a laser diffraction scattering method is defined as D50 , the D50 is 8 μm or more and 25 μm or less.
  5. 　請求項１又は２に記載の蛍光体粉末であって、
    　前記蛍光体は、Ｍの２ｍｏｌ％以上５以下ｍｏｌ％がＣｅとなるように構成される、蛍光体粉末。     The phosphor powder according to claim 1 or 2,
    The phosphor is a phosphor powder configured such that 2 mol % or more and 5 mol % or less of M is Ce.
  6. 　請求項１又は２に記載の蛍光体であって、
    　５００～８５０ｎｍの波長範囲で当該蛍光体の拡散反射率スペクトルを測定したとき、波長７００ｎｍの光に対する拡散反射率Ｘ１と、４５５ｎｍの励起光を照射したときの蛍光ピーク波長の光に対する拡散反射率Ｘ２と、の差分Ｘ１－Ｘ２が、３．０％以下である蛍光体。     The phosphor according to claim 1 or 2,
    A phosphor in which, when the diffuse reflectance spectrum of the phosphor is measured in the wavelength range of 500 to 850 nm, the difference X1-X2 between the diffuse reflectance X1 for light with a wavelength of 700 nm and the diffuse reflectance X2 for light with a fluorescence peak wavelength when irradiated with excitation light of 455 nm is 3.0% or less.
  7. 　請求項１又は２に記載の蛍光体であって、
    　４５５ｎｍの励起光を照射したときの蛍光ピーク波長の光に対する拡散反射率Ｘ２が、８８％以上９７％以下である蛍光体。     The phosphor according to claim 1 or 2,
    A phosphor having a diffuse reflectance X2 of 88% or more and 97% or less for light having a fluorescence peak wavelength when irradiated with excitation light of 455 nm.
  8. 　請求項１又は２に記載の蛍光体であって、
    　４５５ｎｍの励起光を照射したときの蛍光ピークの波長が、５８０ｎｍ以上６１０ｎｍ以下である、蛍光体。     The phosphor according to claim 1 or 2,
    A phosphor having a fluorescence peak wavelength of 580 nm or more and 610 nm or less when irradiated with 455 nm excitation light.
  9. 　請求項１又は２に記載の蛍光体であって、
    　４５５ｎｍの励起光を照射したときの蛍光ピークの半値幅が、１３０ｎｍ以上１４２ｎｍ以下である、蛍光体。     The phosphor according to claim 1 or 2,
    A phosphor having a half-width of a fluorescence peak of 130 nm or more and 142 nm or less when irradiated with an excitation light of 455 nm.
  10. 　請求項１又は２に記載の蛍光体粉末と発光光源とを備える発光装置。 A light emitting device comprising the phosphor powder according to claim 1 or 2 and a light source.
PCT/JP2023/040042 2022-11-11 2023-11-07 Phosphor and light-emitting device WO2024101352A1 (en)

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