Rare earth aluminate fluorescent body and method for producing the same, wave length conversion member, light-emitting device, and projector

Abstract

To provide a rare earth aluminate fluorescent body capable of constituting a wavelength conversion member having a high luminous efficiency and a method for producing the same.SOLUTION: A rare earth aluminate fluorescent body includes: a first element M1 including at least one selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium; cerium; aluminum; and an oxygen element, and may optionally include a second element M2 including at least one selected from gallium and scandium, where a total mole number of the first element M1 and cerium is 2.9 or more and 3.1 or less, and a total mole number of aluminum and the second element M2 is 4.5 or more and 5.5 or less when a mole number of the oxygen element is 12. The rare earth aluminate fluorescent body has a ratio of a reflectance of 280 nm to a reflectance of 380 nm of 0.33 or higher and 0.76 or lower.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rare earth aluminate phosphor, a method for producing the same, a wavelength conversion member, a light emitting device, and a projector.

Background Art

[0002] As a phosphor used in a light emitting device for vehicle-mounted use, general lighting use, a backlight of a liquid crystal display device, a light source device for a projector, etc., together with a light emitting element of a light emitting diode (hereinafter also referred to as "LED") or a semiconductor laser diode (hereinafter also referred to as "LD"), rare earth aluminate phosphors such as yttrium aluminum garnet-based phosphors containing rare earths such as yttrium (hereinafter also referred to as "YAG-based phosphors"), lutetium aluminum garnet-based phosphors containing lutetium (hereinafter also referred to as "LuAG-based phosphors") are known.

[0003] Among rare earth aluminate phosphors, rare earth aluminate phosphors activated with Ce are excited by irradiation with particle beams or electromagnetic waves such as electron beams, vacuum ultraviolet rays, and blue light, and emit light from yellow to green. Since the rare earth aluminate phosphor activated with Ce has short afterglow, a clear image can be obtained. The rare earth aluminate phosphor activated with Ce is used, for example, in a light source device for a projector as shown in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One aspect of the present disclosure aims to provide a rare earth aluminate phosphor capable of forming a wavelength conversion member with higher luminous efficiency and a method for manufacturing the same.

Means for Solving the Problems

[0006] The first aspect includes a first element M containing at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 and cerium (Ce), aluminum (Al), and oxygen atoms (O), and a second element M containing at least one selected from gallium (Ga) and scandium (Sc) 2 When the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, and in the reflection spectrum, the ratio of the reflectance at a wavelength of 280 nm to the reflectance at a wavelength of 380 nm is 0.33 or more and 0.76 or less. It is a rare earth aluminate phosphor.

[0007] The second aspect is a wavelength conversion member including a substrate and a wavelength conversion layer disposed on the substrate and containing a binder and the rare earth aluminate phosphor of the first aspect. The third aspect is a light emitting device including the wavelength conversion member of the second aspect and a light source that irradiates the wavelength conversion member with light. The fourth aspect is a projector including the light emitting device of the third aspect, an image display system, and a projection optical system.

[0008] The fifth aspect is a method for manufacturing a rare earth aluminate phosphor. The manufacturing method includes a first element M containing at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 and cerium (Ce), aluminum (Al), and oxygen atoms (O), and a second element M containing at least one selected from gallium (Ga) and scandium (Sc) 2may be included. When the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, preparing a first rare earth aluminate having such a composition, and subjecting the first rare earth aluminate to a first heat treatment at a temperature of 900°C or higher and lower than 1300°C in a reducing atmosphere to obtain a first heat-treated product.

Advantages of the Invention

[0009] According to one aspect of the present disclosure, it is possible to provide a rare earth aluminate phosphor capable of constituting a wavelength conversion member having higher luminous efficiency and a method for manufacturing the same.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved. In addition, the content of each component in the composition means the total amount of the plurality of substances corresponding to each component in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined with the numerical values exemplified as the numerical ranges. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color names of monochromatic light, etc. follow JIS Z8110. The half-value width of the phosphor means the wavelength width (full width at half maximum; FWHM) of the emission spectrum at which the emission intensity becomes 50% with respect to the maximum emission intensity in the emission spectrum of the phosphor. In this specification, the rare earth aluminate phosphor means a phosphor of aluminate having a garnet crystal structure containing rare earth elements, including YAG-based phosphors and LuAG-based phosphors. Hereinafter, embodiments of the present invention will be described based on the drawings. However, the embodiments shown below are examples of rare earth aluminate phosphors and their manufacturing methods for embodying the technical idea of the present invention, and the present invention is not limited to the rare earth aluminate phosphors and their manufacturing methods shown below.

[0012] Rare earth aluminate phosphor The rare earth aluminate phosphor contains at least one first element M selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) in its composition. 1 And contains cerium (Ce), aluminum (Al), oxygen atoms (O), and may contain at least one selected from gallium (Ga) and scandium (Sc) as required. The second element M 2 May be included. When the number of moles of oxygen atoms is 12, the composition of the rare earth aluminate phosphor may have a total number of moles of the first element M 1 And cerium of 2.9 or more and 3.1 or less, and aluminum and the second element M 2The total molar amount may be 4.5 or more and 5.5 or less. The rare earth aluminate phosphor may have a ratio of the reflectance at a wavelength of 280 nm to the reflectance at a wavelength of 380 nm in its reflection spectrum of 0.33 or more and 0.76 or less.

[0013] The rare earth aluminate phosphor has a specific composition, and by having the reflectance at a wavelength of 280 nm within a specific range in its reflection spectrum, it can exhibit excellent luminous efficiency when constituting, for example, a wavelength conversion member described later. Further, when excited at a short wavelength (for example, 250 nm or more and 300 nm or less, preferably around 280 nm), the fluorescence lifetime tends to be longer, and the luminous efficiency in the wavelength conversion member tends to be further improved. This can be considered, for example, as the influence of the valence change of Ce.

[0014] In the reflection spectrum of the rare earth aluminate phosphor, the reflectance R at a wavelength of 380 nm 380 with respect to the reflectance R at a wavelength of 280 nm 280 The ratio (R 280 / R 380 ) may preferably be 0.36 or more, 0.38 or more, 0.4 or more, 0.45 or more, 0.5 or more, or 0.55 or more, and may preferably be 0.7 or less, 0.66 or less, 0.61 or less, or less than 0.6. When the ratio of the reflectances is within the above range, the luminous efficiency of the wavelength conversion member tends to improve at a high optical power density. The reflectance of the rare earth aluminate phosphor is calculated from the reflection spectrum of the rare earth aluminate phosphor. Also, it can be adjusted by the manufacturing method described later.

[0015] The reflectance R of the rare earth aluminate phosphor at a wavelength of 280 nm 280 may be, for example, 20% or more and 55% or less, preferably 25% or more, 30% or more, or 40% or more, and may be 54% or less, 52% or less, or 50% or less. The reflectance R of the rare earth aluminate phosphor at a wavelength of 380 nm 380It may be, for example, 75% or more and 95% or less, preferably 80% or more, or 85% or more, and may be 92% or less, 90% or less, or 88% or less.

[0016] The rare earth aluminate phosphor has a fluorescence lifetime T at an excitation wavelength of 442 nm 442 with respect to the fluorescence lifetime T at an excitation wavelength of 280 nm 280 The ratio (T 280 / T 442 ) may be, for example, 1.35 or more, preferably 1.4 or more, greater than 1.51, 1.52 or more, 1.53 or more, 1.6 or more, or 1.7 or more. Also, the ratio of the fluorescence lifetimes may be 2.4 or less, or 2 or less. When the ratio of the fluorescence lifetimes is within the above range, the luminous efficiency of the wavelength conversion member, which exhibits excellent luminous efficiency at a high optical power density, tends to increase. Here, the fluorescence lifetime is measured as the time when the number of photons, obtained by exciting the phosphor with a laser pulse having a predetermined wavelength and spectrally analyzing the light with a monochromator, becomes 1 / e of the peak number of photons over time.

[0017] The fluorescence lifetime T of the rare earth aluminate phosphor at an excitation wavelength of 280 nm 280 may be, for example, 75 ns or more, preferably 80 ns or more, or 85 ns or more, and may be, for example, 110 ns or less. The fluorescence lifetime T of the rare earth aluminate phosphor at an excitation wavelength of 442 nm 442 may be, for example, 45 ns or more, preferably 50 ns or more, or 55 ns or more, and may be, for example, 60 ns or less.

[0018] The first element M contained in the composition of the rare earth aluminate phosphor 1 together with aluminum, oxygen atoms, and the second element M optionally contained 2 are elements that constitute the crystal structure of the garnet structure. In the composition of the rare earth aluminate phosphor, the first element M 1may preferably contain at least one selected from the group consisting of Y, Lu, and Tb, and more preferably may contain at least one of Y and Lu. In the composition of the rare earth aluminate phosphor, the first element M 1 when containing Y or Lu, the ratio of the total molar number of Y and Lu to the total molar number of the first element M 1 may be, for example, 0.9 or more and 1.0 or less, preferably 0.95 or more, or 0.99 or more.

[0019] In the composition of the rare earth aluminate phosphor, when the molar number of oxygen atoms is 12, the total molar number of the first element M 1 and cerium may be, for example, 2.9 or more and 3.1 or less, preferably 2.95 or more, or 3.05 or less. Also, the ratio of the molar number of cerium to the total molar number of the first element M 1 and cerium (Ce / (M 1 +Ce)) may be, for example, 0.002 or more and 0.018 or less, preferably 0.0025 or more, 0.003 or more, or 0.004 or more, and 0.015 or less, 0.008 or less, or 0.006 or less.

[0020] The composition of the rare earth aluminate phosphor may optionally contain a second element M 2 . The second element M 2 may contain at least Ga. When the second element M 2 contains Ga, the ratio of the molar number of Ga to the total molar number of the second element M 2 may be, for example, 0.9 or more and 1.0 or less, preferably 0.95 or more, or 0.99 or more.

[0021] In the composition of the rare earth aluminate phosphor, when the molar number of oxygen atoms is 12, the total molar number of aluminum and the second element M 2 may be, for example, 4.5 or more and 5.5 or less, preferably 4.75 or more, or 5.25 or less. Also, the ratio of the molar number of the second element M 2 to the total molar number of aluminum and the second element M 2 (M 2 / (Al + M 2 )) may be, for example, 0 or more and 0.6 or less, preferably 0.4 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.02 or less, or 0.01 or less. The ratio of the number of moles of the second element M 2 to the total number of moles of aluminum and the second element M 2 may preferably be 0.001 or more, 0.003 or more, or 0.006 or more.

[0022] The rare earth aluminate phosphor may have a composition represented by the following formula (1). (M 1 (1-p) Ce p ) q (Al (1-r) M 2 r ) s O 12 (1)

[0023] In formula (1), M 1 may contain at least one selected from the group consisting of Y, La, Lu, Gd, and Tb, and preferably may contain at least one of Y and Lu. M 2 may contain at least one selected from Ga and Sc, and preferably may contain at least Ga. p, q, r, and s may satisfy 0.002 ≤ p ≤ 0.018, 2.9 ≤ q ≤ 3.1, 0 ≤ r ≤ 0.6, 4.5 ≤ s ≤ 5.5, and preferably may satisfy 0.003 ≤ p ≤ 0.01, 2.95 ≤ q ≤ 3.05, 0 ≤ r ≤ 0.2, 4.75 ≤ s ≤ 5.25.

[0024] The rare earth aluminate phosphor may have a number average particle diameter of, for example, 10 μm or more and 60 μm or less, preferably 15 μm or more, or 20 μm or more, and 50 μm or less, or 40 μm or less. When the number average particle diameter of the rare earth aluminate phosphor is within the above range, the emission intensity tends to improve. The number average particle diameter of the rare earth aluminate phosphor is measured, for example, using the Fisher sub-sieve sizer (FSSS) method.

[0025] The particle size distribution of the rare earth aluminate phosphor may show a single-peak particle size distribution, preferably a single-peak particle size distribution with a narrow distribution width, from the viewpoint of, for example, improving luminance. Specifically, in the particle size distribution based on volume, the particle size corresponding to 10% volume cumulative from the smaller diameter side is D 10 , and the particle size corresponding to 90% volume cumulative is D 90 . Then, the ratio of D 10 to D 90 (D 90 / D 10 ) may be, for example, 3.0 or less.

[0026] The emission peak wavelength of the rare earth aluminate phosphor may be, for example, 450 nm or more and 580 nm or less, preferably 490 nm or more, 500 nm or more, 510 nm or more, or 520 nm or more. The upper limit of the emission peak wavelength may preferably be 575 nm or less, 570 nm or less, 560 nm or less, 550 nm or less, 540 nm or less, or 530 nm or less. Also, the full width at half maximum may be, for example, 80 nm or more and 150 nm or less, preferably 90 nm or more, or 95 nm or more, and preferably 140 nm or less, 130 nm or less, 125 nm or less, 110 nm or less, 105 nm or less, or 100 nm or less. Further, the emission color of the rare earth aluminate phosphor has a value of x in the chromaticity coordinates (x, y) in the chromaticity diagram of the CIE1931 color system may be, for example, 0.29 or more and 0.35 or less, preferably 0.299 or more, or 0.338 or less. Also, the value of y may be, for example, 0.52 or more and 0.62 or less, preferably 0.56 or more, or 0.60 or less. The chromaticity coordinates are measured at room temperature (for example, 25 °C) at an excitation wavelength of 442 nm.

[0027] The ratio of the emission intensity of a rare earth aluminate phosphor with a reflectance of 40% to the emission intensity of a rare earth aluminate phosphor with a reflectance of 20% at a wavelength of 280 nm may be, for example, 1 or more and 1.1 or less, preferably 1.02 or more, or 1.04 or more.

[0028] Wavelength conversion member The wavelength conversion member includes a substrate and a wavelength conversion layer disposed on the substrate. The wavelength conversion layer is composed of a binder and a rare earth aluminate phosphor. By including the rare earth aluminate phosphor described above in the wavelength conversion layer, excellent luminous efficiency can be achieved when the wavelength conversion member is configured.

[0029] The luminous efficiency of a light-emitting device composed of a light source, a wavelength conversion member, and an optical system including, for example, a lens and a mirror, is evaluated by the total efficiency which is the product of the fluorescence efficiency in the wavelength conversion member and the light collection efficiency in the optical system. That is, the total efficiency of the light-emitting device means the luminous efficiency of the entire light-emitting device. The fluorescence efficiency corresponds to the wavelength conversion efficiency of the wavelength conversion member and is evaluated as the ratio of the intensity of the emitted light from the wavelength conversion layer to the intensity of the incident light from the light source. Further, the light collection efficiency corresponds to the efficiency with which the emitted light from the wavelength conversion member is taken into the optical system and is evaluated as the ratio of the intensity of the light output from the optical system to the intensity of the emitted light from the wavelength conversion layer.

[0030] Here, with reference to the drawings, a method for evaluating luminous efficiency will be described. FIG. 4 is a schematic configuration diagram showing an example of a light-emitting device. The light-emitting device 200 includes a light source 210, a lens 222 that condenses the light from the light source 210 onto the wavelength conversion member 250, and a dichroic mirror 224 that reflects the output light from the wavelength conversion member 250 and directs the direction of the output light toward the emission direction 230. The wavelength conversion member 250 includes a disk-shaped substrate 252 and a wavelength conversion layer 254 containing a phosphor and a binder. The wavelength conversion layer 254 is disposed, for example, in an annular shape along the circumference of the substrate 252. The luminous efficiency of the light-emitting device 200 is calculated by dividing the fluorescence output (intensity of the emitted light) measured by a power meter at position B by the excitation output (intensity of the incident light) measured by a power meter at position A. In the evaluation of the fluorescence efficiency, it may be confirmed that the rise in the surface temperature is suppressed by measuring the surface temperature of the wavelength conversion layer 254 with an infrared thermograph.

[0031] The substrate constituting the wavelength conversion member may have a disk shape, or may have a shape such as a polygonal plate shape. The thickness of the substrate may be, for example, 0.1 mm or more and 1 mm or less, preferably 0.4 mm or more, or 0.6 mm or less.

[0032] The substrate may be a metal member containing a metal material such as aluminum, iron, copper, silver, nickel, stainless steel, etc. By the substrate being a metal member containing a metal material, the light incident on the wavelength conversion member can be wavelength-converted by the wavelength conversion layer and reflected to the same side as the incident surface. Furthermore, since the heat dissipation from the phosphor is better, the fluorescence efficiency of the wavelength conversion member can be increased.

[0033] Also, the substrate may be a translucent member containing a translucent material such as glass, aluminum oxide, etc. By the substrate being a translucent member, the light incident on the wavelength conversion member can be wavelength-converted by the wavelength conversion layer and emitted to the side opposite to the incident surface. At least one of the main surface on which the wavelength conversion layer of the translucent member is formed or the other main surface facing it may be roughened in advance, for example, by etching or laser processing. Thereby, the light emission unevenness on the light emitting surface of the wavelength conversion member can be suppressed.

[0034] The substrate may have at least a part of its surface serving as a reflective surface. The reflective surface may be formed in at least the region where the wavelength conversion layer is disposed. The reflective surface may be formed of a material containing at least one selected from the group consisting of, for example, silver and aluminum. The reflective surface of the substrate may be formed from the material of the substrate itself. That is, the substrate itself may be formed of a material containing at least one selected from the group consisting of, for example, silver and aluminum, and at least a part of its surface may serve as a reflective surface. Alternatively, the reflective surface may be formed by the surface of a reflective layer disposed on the substrate. Examples of the material for forming the reflective layer include silver, aluminum, an alloy containing at least one selected therefrom, a resin containing a metal oxide such as titanium oxide, and the like. The specular reflectance of the reflective surface may be, for example, 80% or more, preferably 85% or more, or 90% or more. The upper limit of the specular reflectance may be, for example, 100% or less. When the specular reflectance of the reflective surface is 80% or more, there is a tendency to increase the amount of light extraction. Note that the specular reflectance of the reflective surface of the substrate is measured using light with a wavelength of 450 nm.

[0035] The wavelength conversion layer disposed on the substrate may contain a binder and a rare earth aluminate phosphor. The binder constituting the wavelength conversion layer may be an organic binder or an inorganic binder. The organic binder may contain a cured product of a resin, and preferably may contain a cured product of a translucent resin. Examples of the resin include thermosetting resins such as epoxy resin, silicone resin, epoxy-modified silicone resin, and modified silicone resin. When the resin contains a silicone resin, there is a tendency to be more excellent in heat resistance, light resistance, and the like. The silicone resin or the modified silicone resin may contain at least one selected from the group consisting of phenyl silicone resin, modified phenyl silicone resin, dialkyl silicone resin, and modified dialkyl silicone resin. Examples of the inorganic binder include glass, ceramics, aluminum oxide, and the like.

[0036] The content of the binder in the wavelength conversion layer may be, for example, 10% by mass or more and 25% by mass or less, preferably 12% by mass or more, or 14% by mass or more, and also preferably less than 25% by mass, 23% by mass or less, or 20% by mass or less, based on the total mass of the wavelength conversion layer.

[0037] The wavelength conversion layer may further contain other components in addition to the rare earth aluminate phosphor and the binder. Examples of the other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, a light stabilizer, a colorant, and the like. When the wavelength conversion member contains other components, the content thereof can be appropriately selected according to the purpose and the like. For example, when the other component includes a filler, the content thereof can be 0.01 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder.

[0038] The mass ratio of the rare earth aluminate phosphor to the binder contained in the wavelength conversion layer may be, for example, 0.5 or more and 7 or less, preferably 0.8 or more, or 1.0 or more, and also preferably 6 or less.

[0039] The average thickness of the wavelength conversion layer may be, for example, 50 μm or more and 200 μm or less, preferably 60 μm or more, or 70 μm or more, and also preferably 190 μm or less, or 180 μm or less. When the average thickness of the wavelength conversion layer is within the above range, the total efficiency in the light emitting device tends to be further improved. The thickness of the wavelength conversion layer is calculated by subtracting the arithmetic average value of the thickness of the substrate from the arithmetic average value of the total thickness of the wavelength conversion layer and the substrate. The arithmetic average value of the total thickness of the wavelength conversion layer and the substrate and the arithmetic average value of the thickness of the substrate are calculated from the measured values at arbitrary six positions, respectively.

[0040] The wavelength conversion layer may have a substantially uniform thickness. The coefficient of variation of the thickness of the wavelength conversion layer may be, for example, 0.4 or less, preferably 0.3 or less. The lower limit value of the coefficient of variation of the thickness of the wavelength conversion layer may be, for example, 0.09 or more. The coefficient of variation of the thickness of the wavelength conversion layer is calculated by dividing the standard deviation of the thickness of the wavelength conversion layer by the average thickness of the wavelength conversion layer.

[0041] In one aspect, the wavelength conversion member may include a disc-shaped substrate having a reflective surface and a wavelength conversion layer disposed in an annular shape along the circumference of the substrate on the reflective surface of the substrate.

[0042] Light-emitting device The light-emitting device includes a wavelength conversion member and a light source that irradiates the wavelength conversion member with light. The light-emitting device is configured to emit mixed-color light of the light from the light source and the light from the wavelength conversion member irradiated with the light from the light source. By providing the light-emitting device with a wavelength conversion member having a specific configuration, good total efficiency can be achieved. The details of the wavelength conversion member constituting the light-emitting device are as described.

[0043] In one aspect, the light-emitting device may further include a motor that rotates the wavelength conversion member. The wavelength conversion member may be fixed to the rotation axis of the motor and rotatably disposed by the motor.

[0044] Examples of the light source that irradiates the wavelength conversion member with light include light-emitting elements and the like. The light-emitting element may be a semiconductor light-emitting element, and may be a light-emitting diode or a laser diode. The light-emitting elements constituting the light source may be a single type alone or a combination of two or more types. Further, the number of light-emitting elements constituting the light source may be one or a plurality.

[0045] The light source may have an emission peak wavelength, for example, within a wavelength range of 400 nm or more and 500 nm or less. The emission peak wavelength of the light source may preferably be within a wavelength range of 420 nm or more and 480 nm or less. The full width at half maximum of the light source may be, for example, 30 nm or less.

[0046] The output of the light source is, for example, as the optical power density irradiated on the wavelength conversion member, 50 mW / mm 2 or more and 1000 mW / mm 2 or less, and may preferably be 300 W / mm 2 or more, or 600 W / mm 2 or more, and may be 800 W / mm 2 or less, or 700 W / mm 2 or less.

[0047] The light-emitting device can constitute, for example, a projector described later. By using a light-emitting device that exhibits good total efficiency, a high-output projector can be configured. The light-emitting device can be used not only as a light source device for a projector, but also, for example, as a light-emitting device provided in a light source for general lighting devices such as ceiling lights, special lighting devices such as spotlights, stadium lighting, studio lighting, vehicle lighting devices such as headlamps, projection devices such as head-up displays, endoscope lights, imaging devices such as digital cameras, mobile phones, smartphones, light-emitting devices for liquid crystal display devices such as personal computer (PC) monitors, notebook personal computers, televisions, personal digital assistants (PDAs), smartphones, tablet PCs, mobile phones, etc.

[0048] Projector The projector includes the above-described light-emitting device, an image display system, and a projection optical system. In the projector, the mixed light of the light from the light source and the light whose wavelength has been converted by the wavelength conversion member from the light from the light source is irradiated on the image display system. The image display system converts the irradiated light into an image and projects it to the outside through the projection optical system.

[0049] The details of the light source and the wavelength conversion member that make up the projector are as described above. The image display system displays the image projected by the projector. For the image display system, a liquid crystal panel, a digital micromirror device (DMD), etc. can be used. The projection optical system projects the image converted by the image display system from the light emitted from the wavelength conversion member to the outside. The projection optical system consists of a plurality of lenses and can perform zooming, focusing adjustment, etc. The projector is composed of the above configuration and also includes lenses, dichroic mirrors, etc. Further, depending on the design of the projector, it may further include mirrors, dichroic mirrors, lenses, prisms, etc.

[0050] Method for manufacturing rare earth aluminate phosphor The method for manufacturing a rare earth aluminate phosphor includes a first element M containing at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 and cerium (Ce), aluminum (Al), and oxygen atoms (O), and optionally includes at least one selected from gallium (Ga) and scandium (Sc) as a second element M 2 which has a composition that may contain them, and when the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, a preparation step of preparing a first rare earth aluminate having such a composition, and a first heat treatment step of subjecting the first rare earth aluminate to a first heat treatment at a temperature of 900 °C or more and less than 1300 °C in a reducing atmosphere to obtain a first heat-treated product containing a second rare earth aluminate. The second rare earth aluminate may be the target rare earth aluminate phosphor.

[0051] The second rare earth aluminate phosphor contained in the first heat-treated product obtained by heat-treating the first rare earth aluminate in a reducing atmosphere at a specific heat treatment temperature can achieve excellent luminous efficiency when constituting a wavelength conversion member. This can be considered as follows, for example. By heat treatment in an appropriate reducing atmosphere, not only trivalent cerium (Ce 3+ ) that contributes to luminescence, but also tetravalent cerium (Ce 4+ ) that does not directly contribute to luminescence is moderately generated. Under high-density excitation, some of the excited electrons dissipate as heat, but due to the presence of Ce 4+ , some electrons are recaptured, and Ce 4+ changes to Ce 3+ and starts to contribute to luminescence. That is, it is considered that the luminous efficiency is improved by capturing some of the dissipated electrons with Ce 4+ .

[0052] In the preparation step, a first rare earth aluminate having a specific composition is prepared. The first rare earth aluminate may be prepared by transfer or the like, or may be prepared by manufacturing a first rare earth aluminate having a desired composition by a conventional method. The manufacturing method of the first rare earth aluminate will be described later.

[0053] In the first heat treatment step, the prepared first rare earth aluminate is heat-treated at a temperature of 900 °C or higher and less than 1300 °C in a reducing atmosphere to obtain a first heat-treated product. Examples of the first heat treatment in a reducing atmosphere include heat treatment in the presence of a carbon source, heat treatment in an atmosphere containing a reducing gas, etc. Further, the first heat treatment may be heat treatment in an atmosphere where the oxygen concentration is decreasing, for example, heat treatment under reduced pressure. The heat treatment in the presence of a carbon source can be carried out, for example, by using a sealed container containing the first rare earth aluminate and the carbon source and heat-treating the sealed container. At this time, the first rare earth aluminate may be contained in a separate open container from the carbon source, or may be contained in the same container as the carbon source. Further, the heat treatment in the presence of a carbon source may be carried out by arranging a first container containing the first rare earth aluminate on the carbon source and heat-treating a sealed container formed by covering the first container and the carbon source with a second container. By heat-treating together with the carbon source, heat treatment in a reducing atmosphere can be carried out.

[0054] Examples of the carbon source for forming a reducing atmosphere include carbonaceous materials such as activated carbon, carbon black, and carbon nanotubes; hydrocarbon compounds; polymers such as polyolefin, polyvinyl alcohol, phenol resin, and polyamide resin, etc. The reducing atmosphere in the first heat treatment may contain an inert gas. Examples of the inert gas include nitrogen gas and rare gases such as argon. Further, the first heat treatment may be carried out by heat-treating a sealed container containing the first rare earth aluminate and the carbon source in the atmosphere. The amount of the carbon source used may be, for example, 1 mass% or more and 70 mass% or less based on the mass of the first rare earth aluminate, preferably 3 mass% or more, or 50 mass% or less.

[0055] The atmosphere containing a reducing gas may be a mixed atmosphere of a reducing gas and an inert gas. Examples of the reducing gas include hydrogen gas, ammonia gas, carbon monoxide gas, hydrocarbon gas, and the like. Examples of the inert gas include nitrogen gas and rare gases such as argon. When the heat treatment atmosphere contains a reducing gas and an inert gas, the content of the reducing gas in the mixed atmosphere may be, for example, 1% by volume or more and 10% by volume or less, preferably 3% by volume or more and 4% by volume or less.

[0056] The heat treatment temperature in the first heat treatment step may be, for example, a temperature of 900 °C or higher and less than 1300 °C, preferably 950 °C or higher, 1000 °C or higher, or 1050 °C or higher, and may be 1250 °C or lower, 1200 °C or lower, or 1150 °C or lower. When the temperature of the first heat treatment is within the above range, the wheel efficiency tends to increase. The time of the first heat treatment may be, for example, 2 hours or more and 30 hours or less, preferably 4 hours or more, or 26 hours or less. Here, the heat treatment time means the time from reaching a predetermined temperature until the temperature starts to decrease, and the same applies hereinafter. The first heat treatment step can be carried out using, for example, a tubular furnace, a high-frequency furnace, a metal furnace, an atmosphere furnace, a gas pressurizing furnace, or the like.

[0057] The method for producing a rare earth aluminate phosphor may further include a second heat treatment step of second heat-treating the first rare earth aluminate in the presence of oxygen before the first heat treatment step. The wheel efficiency may be further improved by the second heat treatment.

[0058] The atmosphere of the second heat treatment may contain oxygen gas and an inert gas. The oxygen content in the atmosphere of the second heat treatment may be, for example, 10% by volume or more and 30% by volume or less, preferably 15% by volume or more, or 25% by volume or less. The second heat treatment step may be carried out, for example, under the atmosphere.

[0059] The temperature of the second heat treatment may be, for example, 900°C or higher and 1400°C or lower, preferably 1000°C or higher, or 1350°C or lower. Also, the temperature of the second heat treatment may be higher than the temperature of the first heat treatment. The difference between the temperature of the second heat treatment and the temperature of the first heat treatment may be, for example, 10°C or higher and 400°C or lower, preferably 100°C or higher, or 300°C or lower. The time of the second heat treatment may be, for example, 2 hours or longer and 10 hours or shorter, preferably 4 hours or longer, or 8 hours or shorter.

[0060] When the method for producing a rare earth aluminate phosphor includes a second heat treatment step, the first heat treatment step may be continuously performed after cooling to a predetermined temperature after the second heat treatment step. Also, after cooling to near room temperature after the second heat treatment step, the temperature may be raised to a predetermined temperature and the first heat treatment step may be performed in two stages.

[0061] The method for producing a rare earth aluminate phosphor may further include a dispersion step of wet-dispersing the first heat-treated product to obtain a dispersion-treated product. By performing the dispersion treatment, the particle size of the obtained rare earth aluminate phosphor tends to be more uniform. The wet dispersion of the first heat-treated product can be carried out, for example, by dispersing a mixture containing the first heat-treated product and a liquid medium with a bead mill, jet mill, ball mill, disk mill, etc. Examples of the liquid medium used for the dispersion treatment include water, alcohol solvents, ether solvents, ketone solvents such as acetone, and hydrocarbon solvents such as toluene. The content of the liquid medium in the mixture may be, for example, 10% by mass or more and 400% by mass or less based on the mass of the first heat-treated product, preferably 50% by mass or more, or 200% by mass or less.

[0062] When a bead mill is used for the wet dispersion, examples of the material of the beads used include alumina and zirconia. Also, the particle size of the beads may be, for example, 1 mm or more and 10 mm or less. The temperature in the wet dispersion may be, for example, 5°C or higher and 40°C or lower. The time of the dispersion treatment may be, for example, 2 hours or longer and 50 hours or shorter.

[0063] The method for producing a rare earth aluminate phosphor may include solid-liquid separation, drying treatment, classification treatment, etc. after the dispersion step. Solid-liquid separation of the dispersion can be carried out by industrially commonly used methods such as filtration, suction filtration, pressure filtration, centrifugation, decantation, etc. The solid content recovered by solid-liquid separation can be dried using industrially commonly used devices such as a vacuum dryer, a hot air heating dryer, a conical dryer, a rotary evaporator, etc. The drying temperature may be, for example, 50°C or higher and 200°C or lower, preferably 80°C or higher and 130°C or lower. The drying time may be, for example, 0.5 hours or longer and 200 hours or shorter, preferably 1 hour or longer and 20 hours or shorter.

[0064] The method for producing a rare earth aluminate phosphor may further include an acid treatment step of bringing an acidic liquid medium containing an acid component into contact with a first heat-treated product to obtain an acid-treated product. The first heat-treated product to be subjected to the acid treatment step may be the first heat-treated product after the wet dispersion treatment or the first heat-treated product before the wet dispersion treatment. The acidic liquid medium used in the acid treatment step may contain, for example, a liquid medium containing water and an acid component. Examples of the acid component include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid; and organic acids such as formic acid and acetic acid. The acid component contained in the liquid medium may be a single species or a combination of two or more species. The acidic liquid medium may contain at least water, and may contain a water-soluble organic solvent such as alcohol as needed in addition to water. The content of the acid component in the acidic liquid medium may be, for example, 0.1% by mass or higher and 40% by mass or lower, preferably 5% by mass or higher and 10% by mass or lower. The pH of the acidic liquid medium may be, for example, 1.0 or higher and 3.0 or lower, preferably 1.2 or higher or 2.5 or lower. The amount of the acidic liquid medium used for contact with the first heat-treated product may be, for example, 1% by mass or higher and 30% by mass or lower based on the mass of the first heat-treated product, preferably 5% by mass or higher or 20% by mass or lower.

[0065] The contact between the first heat-treated product and the acidic liquid medium can be carried out by mixing the first heat-treated product and the acidic liquid medium in a suitable container. At this time, stirring may be carried out as necessary. The contact temperature between the first heat-treated product and the acidic liquid medium may be, for example, 5°C or higher and 40°C or lower. The contact time may be, for example, 0.1 hour or longer and 10 hours or shorter.

[0066] The method for producing the rare earth aluminate phosphor may include solid-liquid separation, washing treatment, drying treatment, classification treatment, etc. after the acid treatment step.

[0067] The method for producing the rare earth aluminate phosphor may further include a synthesis step of producing the first rare earth aluminate. The synthesis step may include, for example, preparing a raw material mixture and heat-treating the raw material mixture. By heat-treating the raw material mixture having a desired composition, the first rare earth aluminate having the desired composition can be synthesized.

[0068] The raw material mixture includes a first element M including at least one selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium 1 source, a cerium source, and an aluminum source, and may further include a second element M including at least one selected from gallium and scandium as necessary 2 source.

[0069] The first element M constituting the raw material mixture 1 source, the cerium source, the aluminum source, and the second element M 2 sources may include metal compounds, simple substances, alloys, etc. containing the respective metal elements. Examples of the metal compounds include oxides and metal salts. Examples of the metal salts include oxalates, carbonates, halides, nitrates, sulfates, etc. The metal compounds used as raw materials may be in the form of hydrates.

[0070] Specific examples of the first element M 1 source include Y 2 O 3 and La 2 O 3, Lu 2 O 3 , Gd 2 O 3 , Tb 4 O 7 and other oxides such as YCl 3 , Y 2 (C 2 O 4 ) 3 , Y 2 (CO 3 ) 3 , Y(NO 3 ) 3 , Y 2 (SO 4 ) 3 , LaCl 3 , La 2 (C 2 O 4 ) 3 , La 2 (CO 3 ) 3 , La(NO 3 ) 3 , La 2 (SO 4 ) 3 , LuCl 3 , Lu 2 (C 2 O 4 ) 3 , Lu(NO 3 ) 3 , Lu 2 (SO 4 ) 3 , GdCl 3 , TbCl 3 and other metal salts such as. Specifically, as the cerium source, oxides such as CeO 2 and metal salts such as CeCl 3 , Ce 2 (SO 4 ) 3 are included. Specifically, as the aluminum source, oxides such as Al 2 O 3 and metal salts such as AlCl 3 , Al(NO 3 ) 3 , Al 2 (SO 4 ) 3 are included. As the source of the second element M 2 , specifically, Ga2 O 3 、 Sc 2 O 3 oxides such as, GaCl 3 、 Ga(NO 3 ) 3 、 ScCl 3 、 Sc(NO 3 ) 3 and other metal salts.

[0071] The raw material mixture, for example, when the total number of moles of the first element M 1 and cerium is 3, may have a composition in which the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, preferably 4.75 or more, or 5.25 or less. The raw material mixture may have a composition in which the ratio of the number of moles of cerium to the total number of moles of the first element M 1 and cerium is 0.002 or more and 0.018 or less, preferably 0.003 or more, or 0.004 or more, and also preferably 0.015 or less, 0.008 or less, or 0.006 or less. The raw material mixture may have a composition in which the ratio of the number of moles of the second element M 2 to the total number of moles of aluminum and the second element M 2 is 0 or more and 0.6 or less, preferably 0.001 or more, 0.003 or more, or 0.006 or more, and also preferably 0.2 or less, 0.1 or less, 0.05 or less, 0.02 or less, or 0.01 or less.

[0072] The raw material mixture may further contain a specific compound containing at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), magnesium (Mg), and manganese (Mn). Those specific compounds may be compounds that function as a flux in the synthesis process. By including a flux in the raw material mixture, the reaction between the raw materials may be promoted, and the solid-phase reaction may tend to proceed more uniformly. This is presumably because the temperature at which the raw material mixture is heat-treated is approximately the same as or higher than the liquid-phase formation temperature of the compound used as the flux, thus promoting the solid-phase reaction.

[0073] The specific compound may be, for example, a halide, preferably at least one of a fluoride and a chloride, and more preferably a fluoride. The specific compound may be, for example, barium fluoride. By using barium fluoride, it is considered that the garnet crystal structure of the rare earth aluminate is more stabilized and tends to form the composition of the garnet crystal structure. The content of the specific compound in the raw material mixture may be, for example, 0.5% by mass or more and 10% by mass or less, preferably 1.0% by mass or more and 8.0% by mass or less, or 1.5% by mass or more and 7.0% by mass or less. When the content of the specific compound is within the above range, the reaction between the raw materials is more promoted, the solid-phase reaction proceeds more uniformly, and the first rare earth aluminate having the desired composition is likely to be obtained.

[0074] The raw material mixture can be obtained by weighing each raw material so as to have a desired charged composition and then mixing them. As the mixing method, for example, it may be a pulverization mixing using a dry pulverizer such as a ball mill, a vibration mill, a hammer mill, a roll mill, a jet mill, etc., or a pulverization mixing using a mortar and a pestle, etc., or for example, a mixing using a mixer such as a ribbon blender, a Henschel mixer, a V-type blender, etc., or a pulverization mixing using both a dry pulverizer and a mixer. Further, the mixing may be a dry mixing or a wet mixing in which a solvent or the like is added. The mixing may preferably be a dry mixing. Dry mixing can shorten the process time compared to wet mixing and tends to lead to an improvement in productivity.

[0075] The heat treatment of the raw material mixture can be carried out by placing the raw material mixture in a container such as a crucible or a boat. Examples of the material of the container include carbon materials such as graphite, boron nitride (BN), aluminum oxide (alumina), tungsten (W), molybdenum (Mo), etc.

[0076] The temperature of the heat treatment of the raw material mixture may be, for example, 1400 °C or higher and 1800 °C or lower, preferably 1450 °C or higher, 1500 °C or higher, or 1600 °C or higher, and also preferably 1700 °C or lower, or 1650 °C or lower. When the heat treatment temperature is within the above range, the stability of the crystal structure of the first rare earth aluminate tends to be further improved. The heat treatment time may be, for example, 1 hour or longer and 20 hours or shorter, preferably 3 hours or longer, 5 hours or longer, or 8 hours or longer, and also preferably 15 hours or shorter, or 12 hours or shorter. The heat treatment can be carried out using, for example, an electric furnace, a gas furnace, etc.

[0077] The atmosphere of the heat treatment may be, for example, a reducing atmosphere. The reducing atmosphere is as described above. Under a reducing atmosphere, the reactivity of the raw material mixture is improved, and the desired first rare earth aluminate can be obtained by heat treatment under atmospheric pressure without pressurization. Also, by heat-treating the raw material mixture under a reducing atmosphere, tetravalent Ce (Ce 4+ ) becomes trivalent Ce (Ce 3+) is reduced to obtain a first rare earth aluminate in which the proportion of trivalent Ce contributing to luminescence tends to increase.

[0078] The synthesis process may include a crushing / pulverizing process, a washing process, a drying process, a classification process, etc. as necessary after the heat treatment.

[0079] The invention according to the present disclosure may include, for example, the following aspects. [1] A first element M including at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 and cerium (Ce), aluminum (Al), and an oxygen atom (O), and a second element M including at least one selected from gallium (Ga) and scandium (Sc) 2 may be included. When the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, and has a composition A rare earth aluminate phosphor in which the ratio of the reflectance at 280 nm to the reflectance at 380 nm is 0.33 or more and 0.76 or less.

[0080] [2] The rare earth aluminate phosphor according to [1], wherein the ratio of the fluorescence lifetime at an excitation wavelength of 280 nm to the fluorescence lifetime at an excitation wavelength of 442 nm is greater than 1.51.

[0081] [3] The ratio of the number of moles of cerium to the total number of moles of the first element M 1 is 0.002 or more and 0.018 or less, and the ratio of the number of moles of the second element M to the total number of moles of the aluminum and the second element M 2 is 0.6 or less, and the rare earth aluminate phosphor according to [1] or [2] having a composition. 2

[0082] [4] The rare earth aluminate phosphor according to any one of [1] to [3], having a composition represented by the following formula (1). (M 1 (1-p) Ce p ) q (Al (1-r) M 2 r ) s O 12 (1)

[0083] In formula (1), M 1 includes at least one selected from the group consisting of Y, La, Lu, Gd, and Tb. M 2 includes at least one selected from Ga and Sc. p, q, r, and s satisfy 0.002 ≤ p ≤ 0.018, 2.9 ≤ q ≤ 3.1, r ≤ 0.6, and 4.5 ≤ s ≤ 5.5.

[0084] [5] The rare earth aluminate phosphor according to any one of [1] to [4], having a number average particle diameter of 10 μm or more and 60 μm or less.

[0085] [6] The rare earth aluminate phosphor according to any one of [1] to [5], wherein the x value in the chromaticity coordinates of the CIE1931 color system of the emission color at an excitation wavelength of 450 nm is 0.29 or more and 0.35 or less.

[0086] [7] A wavelength conversion member including a substrate and a wavelength conversion layer disposed on the substrate and containing a binder and the rare earth aluminate phosphor according to any one of [1] to [6].

[0087] [8] The wavelength conversion member according to [7], wherein the wavelength conversion layer has a content of the rare earth aluminate phosphor of 50 parts by mass or more and 700 parts by mass or less with respect to 100 parts by mass of the binder.

[0088] [9] The wavelength conversion member according to [7] or [8], wherein the wavelength conversion layer has an average thickness of 50 μm or more and 200 μm or less.

[0089] A light-emitting device comprising: a wavelength conversion member according to any one of [7] to [9]; and a light source that irradiates the wavelength conversion member with light.

[0090]

[11] The light source has a light power density irradiated on the wavelength conversion member of 50 mW / mm 2 or more and 1000 mW / mm 2 or less. The light-emitting device according to

[10] .

[0091]

[12] A projector comprising: the light-emitting device according to

[10] or

[11] ; an image display system; and a projection optical system.

[0092]

[13] A first rare earth aluminate phosphor having a composition containing at least one kind selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) as a first element M 1 and cerium (Ce), aluminum (Al), and oxygen atoms (O), and optionally containing at least one kind selected from gallium (Ga) and scandium (Sc) as a second element M 2 and when the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, and preparing the first rare earth aluminate; performing a first heat treatment on the first rare earth aluminate at a temperature of 900 °C or more and less than 1300 °C in a reducing atmosphere to obtain a first heat-treated product. A method for producing a rare earth aluminate phosphor, comprising:

[0093]

[14] The method for production according to

[13] , wherein the first heat treatment is performed in the presence of a carbon source.

[0094]

[15] The method for production according to

[13] or

[14] , further comprising performing a second heat treatment on the first rare earth aluminate in the presence of oxygen before the first heat treatment.

[0095]

[16] The manufacturing method described in

[15] , wherein the temperature of the second heat treatment is higher than the temperature of the first heat treatment.

[0096]

[17] The manufacturing method according to any one of

[13] to

[16] , further comprising wet-dispersing the first heat-treated product.

[0097]

[18] The manufacturing method according to any one of

[13] to

[17] , further comprising bringing the first heat-treated product into contact with an acidic liquid medium.

Example

[0098] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0099] Reference Example 1 1669.2 g (4.194 mol) of lutetium oxide (Lu 2 O 3 ), 12.12 g (0.07046 mol) of cerium oxide (CeO 2 ), 718.7 g (7.046 mol) of aluminum oxide (Al 2 O 3 ), 144 g (0.8214 mol) of barium fluoride (BaF 2 ), and 12 g (0.06403 mol) of gallium oxide (Ga 2 O 3 ) were weighed, placed in a polyethylene container together with alumina balls, and ball-milled for 4 hours to obtain a raw material mixture. The raw material mixture was filled into an alumina crucible and placed on a board covered with activated carbon. A large alumina crucible was placed over the alumina crucible filled with the raw material mixture. By heat-treating at 1625 °C for 10 hours using an electric furnace, a first rare earth aluminate was obtained.

[0100] Example 1 The first rare earth aluminate obtained in Reference Example 1 was filled into an alumina crucible and heat-treated at 1300 °C for 6 hours in an air atmosphere. Next, the alumina crucible was placed on a board covered with activated carbon, and a large alumina crucible was placed over the alumina crucible filled with the first rare earth aluminate to cover it, and heat treatment was performed at a first heat treatment temperature of 1100 °C for 6 hours to obtain a first heat-treated product.

[0101] The obtained first heat-treated product was subjected to wet dispersion treatment and acid treatment as follows to obtain a rare earth aluminate phosphor. 100 g of the obtained first heat-treated product, 200 g of pure water, and 100 g of φ2 mm alumina beads were put into a polyethylene container and dispersed at room temperature (25 °C) for 15 hours. Coarse particles were removed by passing through a sieve. Acid washing was performed using hydrochloric acid, and sedimentation classification was performed to remove fine particles. Drying treatment was performed to obtain the rare earth aluminate phosphor of Example 1.

[0102] When the obtained first rare earth aluminate was analyzed by high-frequency inductively coupled plasma (ICP) emission spectrometry, it had the composition shown below. Lu 2.986 Ce 0.014 Al 4.952 Ga 0.036 O 12

[0103] Example 2 A rare earth aluminate phosphor of Example 2 was obtained in the same manner as in Example 1, except that heat treatment in an air atmosphere was not performed.

[0104] Example 3 A rare earth aluminate phosphor of Example 3 was obtained in the same manner as in Example 2, except that the first heat treatment temperature was changed to 1000 °C.

[0105] Comparative Example 1 A rare earth aluminate phosphor of Comparative Example 1 was obtained in the same manner as in Example 2, except that the first heat treatment temperature was changed to 1400 °C.

[0106] Comparative Example 2 A rare earth aluminate phosphor of Comparative Example 2 was obtained in the same manner as in Example 2, except that the first heat treatment temperature was changed to 1300°C.

[0107] Comparative Example 3 A rare earth aluminate phosphor of Comparative Example 3 was obtained in the same manner as in Example 1, except that the first rare earth aluminate obtained in Reference Example 1 was heat-treated at 1100°C for 6 hours in an air atmosphere to obtain a heat-treated product, and the obtained heat-treated product was subjected to wet dispersion treatment and acid treatment.

[0108] Comparative Example 4 A rare earth aluminate phosphor of Comparative Example 4 was obtained in the same manner as in Comparative Example 3, except that the heat treatment temperature was changed to 1300°C.

[0109] Evaluation The following evaluations were performed on the rare earth aluminate phosphors obtained above.

[0110] Number average particle diameter The number average particle diameter was measured by the FSSS method using a Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific). The results are shown in Table 1.

[0111] Luminescence characteristics Regarding the rare earth aluminate phosphors obtained above, using a quantum efficiency measurement system (QE-2000, manufactured by Otsuka Electronics Co., Ltd.), excitation light with a emission peak wavelength of 450 nm was irradiated to measure the emission spectrum. From the emission spectrum, the chromaticity coordinates (x, y) in the chromaticity coordinate system of the CIE (International Commission on Illumination) 1931 chromaticity diagram, the emission intensity at the emission peak wavelength, the emission peak wavelength (nm), and the full width at half maximum (FWHM) (nm) of the emission spectrum were determined. The relative emission intensity (%) was calculated as the relative value of the emission intensity of each phosphor with respect to 100% of the emission intensity of the phosphor of the comparative example.

[0112] Reflection spectrum For the rare earth aluminate phosphors of Example 1 and Comparative Example 1, using a spectrofluorometer (F-4500, manufactured by Hitachi High-Technologies Corporation), at room temperature (25 ± 5 °C), light from a halogen lamp serving as an excitation light source was irradiated onto each phosphor serving as a sample, and the reflection spectrum of each phosphor was measured by scanning while matching the wavelengths of the spectrometers on the excitation side and the phosphor side. The reflection spectrum with the reflectance of calcium hydrogen phosphate (CaHPO 4 ) set to 100% is shown in Fig. 1.

[0113] Reflectance For the rare earth aluminate phosphors obtained above, using a spectrofluorometer (F-4500, manufactured by Hitachi High-Technologies Corporation), at room temperature (25 ± 5 °C), light from a halogen lamp serving as an excitation light source was irradiated onto each phosphor serving as a sample, and the reflectance at a wavelength of 280 nm and the reflectance at a wavelength of 380 nm were measured by scanning while matching the wavelengths of the spectrometers on the excitation side and the phosphor side. Note that the reflectance of calcium hydrogen phosphate (CaHPO 4 ) was set to 100% as a reference.

[0114] The relationship between the reflectance at a wavelength of 280 nm and the relative emission intensity obtained by measuring the emission characteristics is shown in Fig. 2.

[0115] Fluorescence lifetime Each phosphor was irradiated with excitation light having an emission peak wavelength of 280 nm or 442 nm, and the change over time in the fluorescence intensity of each phosphor was measured using a small fluorescence lifetime device (Quantaurus-Tau, manufactured by Hamamatsu Photonics K.K.) from the time when the irradiation of the excitation light was blocked. Using the fluorescence intensity at the time of blocking the excitation light as 100%, the time when the fluorescence intensity became 1 / e of that at the time of blocking the excitation light was measured as the fluorescence lifetime. The results are shown in Table 1. "-" in Table 1 indicates that it does not apply or that it was not measured.

[0116]

Table 1

[0117] Fabrication of wavelength conversion member As a substrate, a disk-shaped substrate made of a metal containing aluminum, with a diameter of 65 mm and a thickness of 0.50 mm, was prepared. The specular reflectance of the substrate at 450 nm on the reflective surface was 98.2%.

[0118] 500 parts by mass of each of the rare earth aluminate phosphors obtained above was added to 100 parts by mass of a dimethyl silicone resin and mixed with a vacuum degassing mixer to obtain a phosphor composition. The obtained phosphor composition was applied onto the substrate by screen printing to form a phosphor composition layer. Then, a wavelength conversion layer was formed by heat treatment in an oven at 60 °C for 4 hours and then in an oven at 150 °C for 4 hours to obtain each wavelength conversion member.

[0119] Relative luminous efficiency For each of the obtained wavelength conversion members, the relative luminous efficiency (%) was determined as follows. Laser light from a laser diode with a wavelength of 450 nm was irradiated onto the wavelength conversion member through a dichroic mirror with an incident light beam diameter of Φ1 mm and an intensity of 90 W. The radiant flux of the light emitted from the same surface as the surface on which the laser light was incident was separated by a dichroic mirror, and the intensity of the emitted light was measured using an integrating sphere. The luminous efficiency was obtained by dividing the intensity of the emitted light by the intensity of the incident light. Taking the luminous efficiency of the wavelength conversion member obtained using the rare earth aluminate phosphor of Comparative Example 1 as a reference of 100%, the relative luminous efficiency (%) was determined for the luminous efficiency of the wavelength conversion members obtained using the rare earth aluminate phosphors of each Example and Comparative Example. The results are shown in Table 2.

[0120]

Table 2

Explanation of symbols

[0121] 200 Light emitting device 210 Light source 250 Wavelength conversion member

Claims

1. A first element M containing at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) １ And a second element M containing cerium (Ce), aluminum (Al), an oxygen atom (O), and containing at least one selected from gallium (Ga) and scandium (Sc) ２ May be included, and when the number of moles of oxygen atoms is 12, the first element M １ And the total number of moles of cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M ２ Has a composition in which the total number of moles is 4.5 or more and 5.5 or less A rare earth aluminate phosphor in which the ratio of the reflectance at a wavelength of 280 nm to the reflectance at a wavelength of 380 nm in the reflection spectrum is 0.33 or more and 0.76 or less.

2. The rare earth aluminate phosphor according to Claim 1, wherein the ratio of the fluorescence lifetime at an excitation wavelength of 280 nm to the fluorescence lifetime at an excitation wavelength of 442 nm is greater than 1.

51.

3. the first element M １ the ratio of the number of moles of cerium to the total number of moles of cerium and the first element M is 0.002 or more and 0.018 or less, The aluminum and the second element M ２ The molar ratio of the second element M to the total molar amount of ２ The rare earth aluminate phosphor according to claim 1, having a composition in which the molar ratio of M is 0.6 or less.

4. The rare earth aluminate phosphor according to Claim 1, having a composition represented by the following formula (1). (M １ （１－ｐ） Ce ｐ ) ｑ (Al （１－ｒ） M ２ ｒ ) ｓ O １２ (1) (In formula (1), M １ comprises at least one selected from the group consisting of Y, La, Lu, Gd, and Tb. M ２ comprises at least one selected from Ga and Sc. p, q, r, and s satisfy 0.002 ≤ p ≤ 0.018, 2.9 ≤ q ≤ 3.1, r ≤ 0.6, and 4.5 ≤ s ≤ 5.5.)

5. The rare earth aluminate phosphor according to Claim 1, having a number average particle diameter of 10 μm or more and 60 μm or less.

6. The rare earth aluminate phosphor according to Claim 1, wherein the x value in the chromaticity coordinates of the CIE1931 color system of the emission color at an excitation wavelength of 450 nm is 0.29 or more and 0.35 or less.

7. A wavelength conversion member including a substrate and a wavelength conversion layer disposed on the substrate and including a binder and the rare earth aluminate phosphor according to any one of Claims 1 to 6.

8. The wavelength conversion member according to Claim 7, wherein the content of the rare earth aluminate phosphor in the wavelength conversion layer is 50 parts by mass or more and 700 parts by mass or less with respect to 100 parts by mass of the binder.

9. The wavelength conversion member according to Claim 7, wherein the average thickness of the wavelength conversion layer is 50 μm or more and 200 μm or less.

10. A light emitting device including the wavelength conversion member according to any one of Claims 7 to 9 and a light source that irradiates the wavelength conversion member with light.

11. The light source has a light power density irradiated on the wavelength conversion member of 50 mW / mm ２ or more and 1000 mW / mm ２ or less, and the light-emitting device according to claim 10.

12. A projector including the light emitting device according to Claim 10, an image display system, and a projection optical system.

13. A first element M containing at least one selected from the group consisting of yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) １ A second element M containing cerium (Ce), aluminum (Al), an oxygen atom (O), and optionally at least one selected from gallium (Ga) and scandium (Sc) ２ When the number of moles of oxygen atoms is 12, the total number of moles of the first element M １ and cerium is 2.9 or more and 3.1 or less, and the total number of moles of aluminum and the second element M ２ is 4.5 or more and 5.5 or less, to prepare a first rare earth aluminate having a composition A method for manufacturing a rare earth aluminate phosphor, including subjecting the first rare earth aluminate to a first heat treatment at a temperature of 900°C or more and less than 1300°C in a reducing atmosphere to obtain a first heat treated product.

14. The manufacturing method according to Claim 13, wherein the first heat treatment is performed in the presence of a carbon source.

15. The manufacturing method according to Claim 13, further including subjecting the first rare earth aluminate to a second heat treatment in the presence of oxygen before the first heat treatment.

16. The manufacturing method according to Claim 15, wherein the temperature of the second heat treatment is higher than the temperature of the first heat treatment.

17. The manufacturing method according to Claim 13, further including wet-dispersing the first heat treated product.

18. The manufacturing method according to claim 13, further comprising bringing the first heat-treated product into contact with an acidic liquid medium.

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