Rare earth aluminate phosphor, method for producing same, wavelength conversion member, light-emitting device, and projector

Abstract

Provided are: a rare-earth aluminate phosphor which is capable of constituting a wavelength conversion member having higher luminous efficiency; and a method for producing the rare-earth aluminate phosphor. A rare earth aluminate phosphor having a composition containing a first element (M1) containing at least one element selected from yttrium, lanthanum, lutetium, gadolinium, and terbium, cerium, aluminum, and oxygen atoms, and optionally containing or not containing a second element (M2) containing at least one element selected from gallium and scandium, and having a molar ratio of 1: 1 when the number of moles of oxygen atoms is 12. The total number of moles of the first element M1 and cerium is 2.9 to 3.1 inclusive, and the total number of moles of the aluminum and the second element M2 is 4.5 to 5.5 inclusive. The ratio of the reflectance at 280 nm to the reflectance at 380 nm of the rare earth aluminate phosphor is from 0.33 to 0.76 (inclusive).

Description

Technical Field

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

[0002] As phosphors used together with light emitting elements such as light emitting diodes (hereinafter also referred to as "LEDs") or semiconductor laser diodes (hereinafter also referred to as "LDs") in vehicle-mounted, general lighting light emitting devices, backlights for liquid crystal display devices, light source devices for projectors, etc., rare earth aluminate phosphors such as yttrium aluminum garnet phosphors containing rare earths such as yttrium (hereinafter also referred to as "YAG phosphors"), lutetium aluminum garnet phosphors containing lutetium (hereinafter also referred to as "LuAG phosphors") are known.

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

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-138168 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] An object of one aspect of the present invention is to provide a rare earth aluminate phosphor and a method for manufacturing the same, which can be made into a wavelength conversion member with higher luminous efficiency.

[0009] Means for Solving the Problems

[0010] The first aspect relates to a rare earth aluminate phosphor having the following composition: containing a first element M containing at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 , cerium (Ce), aluminum (Al), oxygen atoms (O), and optionally containing or not containing 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 first element M 1The total molar amount of [Element 1] and cerium is 2.9 or more and 3.1 or less, and the total molar amount of aluminum and the second element M 2 is 4.5 or more and 5.5 or less. 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.

[0011] The second aspect relates to a wavelength conversion member including a substrate and a wavelength conversion layer disposed on the substrate and containing a binder material and a rare earth aluminate phosphor of the first aspect. The third aspect relates to a light-emitting device including the wavelength conversion member of the second aspect and a light source that irradiates light to the wavelength conversion member. The fourth aspect relates to a projector including the light-emitting device of the third aspect, an image display system, and a projection optical system.

[0012] The fifth aspect relates to a method for manufacturing a rare earth aluminate phosphor. The manufacturing method includes preparing a first rare earth aluminate and 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. The first rare earth aluminate has the following composition: including a first element M containing at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb), 1 cerium (Ce), aluminum (Al), oxygen atoms (O), and optionally containing or not containing a second element M containing at least one selected from gallium (Ga) and scandium (Sc). 2 When the molar amount of oxygen atoms is 12, the total molar amount of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total molar amount of aluminum and the second element M 2 is 4.5 or more and 5.5 or less.

[0013] Advantages of the Invention

[0014] According to one aspect of the present disclosure, a phosphor and a method for manufacturing the same of a rare earth aluminate phosphor can be provided, and the phosphor can be formed into a wavelength conversion member with higher luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an example of the reflection spectrum of a rare earth aluminate phosphor.

[0016] Figure 2 is a graph showing the relationship between the relative luminous intensity and the reflectance of a rare earth aluminate phosphor.

[0017] Figure 3 is a graph showing the relationship between the luminous efficiency of a wavelength conversion member and the reflectance of a rare earth aluminate phosphor.

[0018] Figure 4 This is a schematic structural diagram showing an example of the structure of a light-emitting device.

[0019] Symbol Explanation

[0020] 200 Light-emitting device

[0021] 210 Light source

[0022] 250 Wavelength conversion member Detailed Embodiment

[0023] In this specification, the term "process" not only refers to an independent process, but also includes this term when it cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved. In addition, when there are multiple substances corresponding to each component in the composition, as long as there is no characteristic limitation, the content of each component in the composition represents the total amount of the multiple substances present in the composition. Further, the upper and lower limits of the numerical range described in this specification can be arbitrarily selected and combined from the numerical values exemplified as the numerical range. 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. are all based on JIS Z8110. The half-value width of a phosphor refers to the wavelength width (full width at half maximum; FWHM) of the emission spectrum of the phosphor at which the emission intensity reaches 50% of the maximum emission intensity. In this specification, rare earth aluminate phosphors refer to phosphors having a garnet crystal structure containing rare earth elements, and also include YAG-based phosphors and LuAG-based phosphors. Hereinafter, embodiments of the present invention will be described based on the drawings. However, the rare earth aluminate phosphors and their manufacturing methods exemplified in the following embodiments are used to embody 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.

[0024] Rare earth aluminate phosphor

[0025] The rare earth aluminate phosphor contains in its composition a first element M containing at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 , cerium (Ce), aluminum (Al), oxygen atoms (O), and optionally contains or does not contain a second element M containing at least one selected from gallium (Ga) and scandium (Sc) 2 . In the composition of the rare earth aluminate phosphor, when the number of moles of oxygen atoms is 12, the total number of moles of the first element M 1 and cerium can be 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 ratio of the reflectance at a wavelength of 280 nm to the reflectance at a wavelength of 380 nm in the reflection spectrum of the rare earth aluminate phosphor may be 0.33 or more and 0.76 or less.

[0026] The rare earth aluminate phosphor has a specific composition. By making the reflectance at a wavelength of 280 nm in the reflection spectrum within a specific range, excellent luminous efficiency is exhibited when, for example, a wavelength conversion member described later is fabricated. 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 becomes longer, and there is a tendency for the luminous efficiency of the wavelength conversion member to further increase. It is considered that this is affected by, for example, the valence change of Ce.

[0027] In the reflection spectrum of the rare earth aluminate phosphor, the reflectance R at a wavelength of 280 nm 280 relative to the reflectance R at a wavelength of 380 nm 380 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, there is a tendency for the luminous efficiency of the wavelength conversion member to increase at a high light power density. The reflectance of the rare earth aluminate phosphor is calculated from the reflection spectrum of the rare earth aluminate phosphor. Further, it can be adjusted according to the manufacturing method described later.

[0028] 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 380 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.

[0029] The fluorescence lifetime T of the rare earth aluminate phosphor at an excitation wavelength of 280 nm 280 relative to the fluorescence lifetime T at an excitation wavelength of 442 nm 442 The ratio (T 280 / T 442) It can be, for example, 1.35 or more, preferably 1.4 or more, greater than 1.51, can be 1.52 or more, 1.53 or more, 1.6 or more, or 1.7 or more. Additionally, the fluorescence lifetime ratio can be 2.4 or less, or can be 2 or less. When the fluorescence lifetime ratio is within the above range, the luminous efficiency of the wavelength conversion member showing excellent luminous efficiency at high light power density tends to increase. Here, the fluorescence lifetime is measured by spectroscopically separating the light obtained by exciting the phosphor with a laser pulse having a given wavelength using a monochromator and measuring the number of photons over time, and is determined as the time when the number of photons reaches 1 / e of the peak number.

[0030] The fluorescence lifetime T of the rare earth aluminate phosphor at an excitation wavelength of 280 nm 280 can be, for example, 75 ns or more, preferably 80 ns or more, or can be 85 ns or more, and can 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 can be, for example, 45 ns or more, preferably 50 ns or more, or 55 ns or more, and can be, for example, 60 ns or less.

[0031] The first element M contained in the composition of the rare earth aluminate phosphor 1 , aluminum, oxygen atoms, and the second element M contained as needed 2 are all elements constituting the crystal structure of the garnet structure. Regarding the composition of the rare earth aluminate phosphor, the first element M 1 preferably contains at least one selected from Y, Lu, and Tb, and more preferably contains at least one of Y and Lu. In the composition of the rare earth aluminate phosphor, when the first element M 1 contains Y or Lu, the total molar ratio of Y and Lu to the total molar number of the first element M 1 can be, for example, 0.9 or more and 1.0 or less, preferably 0.95 or more, or can be 0.99 or more.

[0032] Regarding 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 can be, for example, 2.9 or more and 3.1 or less, preferably 2.95 or more, or can be 3.05 or less. Additionally, the molar ratio of cerium to the total molar number of the first element M 1 and cerium (Ce / (M 1 +Ce)) can be, for example, 0.002 or more and 0.018 or less, preferably 0.0025 or more, 0.003 or more, or can be 0.004 or more, can be 0.015 or less, 0.008 or less, or can be 0.006 or less.

[0033] Regarding the composition of the rare earth aluminate phosphor, the second element M may be optionally included or not included as needed. 2 . The second element M 2 may contain at least Ga. When the second element M 2 contains Ga, the molar ratio of Ga to the total molar amount 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 may be 0.99 or more.

[0034] Regarding the composition of the rare earth aluminate phosphor, when the molar amount of oxygen atoms is 12, the total molar amount 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 may be 5.25 or less. Further, the molar ratio of the second element M 2 to the total molar amount 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 may be 0.01 or less. The molar ratio of the second element M 2 to the total molar amount of aluminum and the second element M 2 is preferably 0.001 or more, 0.003 or more, or 0.006 or more.

[0035] The rare earth aluminate phosphor may have a composition represented by the following formula (1).

[0036] (M 1 (1-p) Ce p ) q (Al (1-r) M 2 r ) s O 12 (1)

[0037] In formula (1), M 1 may contain at least one selected from 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 satisfy 0.002 ≤ p ≤ 0.018, 2.9 ≤ q ≤ 3.1, 0 ≤ r ≤ 0.6, 4.5 ≤ s ≤ 5.5, and preferably satisfy 0.003 ≤ p ≤ 0.01, 2.95 ≤ q ≤ 3.05, 0 ≤ r ≤ 0.2, 4.75 ≤ s ≤ 5.25.

[0038] The number average particle diameter of the rare earth aluminate phosphor can be, for example, 10 μm or more and 60 μm or less, preferably 15 μm or more, or can be 20 μm or more, can be 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, there is a tendency for the luminous intensity to increase. The number average particle diameter of the rare earth aluminate phosphor is measured by, for example, the Fisher Sub-Sieve Sizer (FSSS) method.

[0039] From the viewpoint of improving brightness, the particle size distribution of the rare earth aluminate phosphor can show, for example, a unimodal particle size distribution, preferably a unimodal particle size distribution with a narrow distribution width. Specifically, in the particle size distribution based on volume, if the particle size corresponding to the cumulative volume of 10% from the small particle size side is set as D 10 and the particle size corresponding to the cumulative volume of 90% is set as D 90 , then the ratio of D 90 to D 10 (D 90 / D 10 ) can be, for example, 3.0 or less.

[0040] The emission peak wavelength of the rare earth aluminate phosphor can 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 is preferably 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. In addition, the full width at half maximum can be, for example, 80 nm or more and 150 nm or less, preferably 90 nm or more, or 95 nm or more, preferably can be 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. In addition, for the emission color of the rare earth aluminate phosphor in the chromaticity coordinates (x, y) of the CIE1931 chromaticity diagram, the value of x can be, for example, 0.29 or more and 0.35 or less, preferably 0.299 or more, or can be 0.338 or less. In addition, the value of y can be, for example, 0.52 or more and 0.62 or less, preferably 0.56 or more, or can be 0.60 or less. The chromaticity coordinates are measured at room temperature (e.g., 25 °C) at an excitation wavelength of 442 nm.

[0041] The ratio of the luminous intensity of the rare earth aluminate phosphor with a reflectance of 40% at a wavelength of 280 nm to the luminous intensity of the rare earth aluminate phosphor with a reflectance of 20% can be, for example, 1 or more and 1.1 or less, preferably 1.02 or more, or can be 1.04 or more.

[0042] Wavelength conversion member

[0043] 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 material and a rare earth aluminate phosphor. By including the rare earth aluminate phosphor in the wavelength conversion layer, excellent luminous efficiency can be achieved when the wavelength conversion member is formed.

[0044] The luminous efficiency of a light-emitting device composed of a light source, a wavelength conversion member, and an optical system (e.g., including a lens and a mirror) is evaluated by the total efficiency, which is the product of the fluorescence efficiency of the wavelength conversion member and the light collection efficiency of the optical system. That is, the total efficiency of the light-emitting device refers to the luminous efficiency of the entire light-emitting device. The fluorescence efficiency is equivalent to the wavelength conversion efficiency of the wavelength conversion member and is evaluated in the form of the ratio of the intensity of the light emitted from the wavelength conversion layer to the intensity of the incident light from the light source. In addition, the light collection efficiency is equivalent to the efficiency of the light emitted from the wavelength conversion member being collected into the optical system and is evaluated in the form of the ratio of the intensity of the light output from the optical system to the intensity of the light emitted from the wavelength conversion layer.

[0045] Here, the method for evaluating the luminous efficiency will be described with reference to the drawings. Figure 4 It is a schematic structural diagram showing an example of the light-emitting device. The light-emitting device 200 includes: a light source 210, a lens 222 that condenses the light emitted 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 output light in 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 material. The wavelength conversion layer 254 is disposed, for example, in a circular ring shape along the circumference of the substrate 252. The luminous efficiency of the light-emitting device 200 is calculated as follows: dividing the excitation output power (incident light intensity) measured by a power meter at position A by the fluorescence output power (emitted light intensity) measured by a power meter at position B. It should be noted that for the evaluation of the fluorescence efficiency, the surface temperature of the wavelength conversion layer 254 can be measured by an infrared thermography method to determine that the rise in the surface temperature is suppressed.

[0046] The substrate constituting the wavelength conversion member can have a disk shape or a polygonal plate shape, etc. The thickness of the substrate can be, for example, 0.1 mm or more and 1 mm or less, preferably 0.4 mm or more, or can be 0.6 mm or less.

[0047] The substrate may be, for example, a metal member including a metal material such as aluminum, iron, copper, silver, nickel, stainless steel, etc. Since the substrate is a metal member including a metal material, the light incident on the wavelength conversion member is wavelength-converted by the wavelength conversion layer and can be reflected to the same side as the incident surface. Further, since the heat dissipation of the phosphor becomes better, the fluorescence efficiency of the wavelength conversion member can be increased.

[0048] Alternatively, the substrate may be, for example, a light-transmissive member including a light-transmissive material such as glass, alumina, etc. Since the substrate is a light-transmissive member, the light incident on the wavelength conversion member can be wavelength-converted by the wavelength conversion layer and emitted to the opposite side of the incident surface. At least one of the main surface formed by the wavelength conversion layer of the light-transmissive member or another main surface opposite thereto may be roughened in advance by, for example, etching, laser processing, etc. Thereby, the uneven emission of the light-emitting surface of the wavelength conversion member can be suppressed.

[0049] At least a part of the surface of the substrate may be 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 including at least one selected from silver and aluminum. The reflective surface of the substrate may be formed by the material of the substrate itself. That is, the substrate itself is formed of a material including at least one selected from silver and aluminum, and at least a part of its surface is 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 including at least one of them, a resin including a metal oxide such as titanium oxide, etc. The specular reflectance of the reflective surface may be, for example, 80% or more, preferably 85% or more, or may be 90% or more. The upper limit of the specular reflectance may be, for example, 100% or less. By making the specular reflectance of the reflective surface 80% or more, there is a tendency to further increase the light extraction amount. It should be noted that the specular reflectance of the reflective surface of the substrate is measured using light with a wavelength of 450 nm.

[0050] The wavelength conversion layer disposed on the substrate may include a binder material and a rare earth aluminate phosphor. The binder material constituting the wavelength conversion layer may be an organic binder material or an inorganic binder material. The organic binder material may contain a cured product of a resin, preferably a cured product of a light-transmissive resin. Examples of the resin include thermosetting resins such as epoxy resin, silicone resin, epoxy-modified silicone resin, and modified silicone resin. By making the resin contain silicone resin, there is a tendency to have more excellent heat resistance, light resistance, etc. The silicone resin or modified silicone resin may include at least one selected from phenyl silicone resin, modified phenyl silicone resin, dialkyl silicone resin, and modified dialkyl silicone resin. Examples of the inorganic binder material include glass, ceramics, alumina, etc.

[0051] The content of the binder material in the wavelength conversion layer can 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, preferably less than 25% by mass, 23% by mass or less, or 20% by mass or less, relative to the total mass of the wavelength conversion layer.

[0052] In addition to the rare earth aluminate phosphor and the binder material, the wavelength conversion layer may further contain other components. Examples of other components include: fillers such as silica, barium titanate, titanium oxide, and alumina, light stabilizers, colorants, etc. When the wavelength conversion member contains other components, their contents can be appropriately selected according to the purpose, etc. For example, when a filler is included as other components, the content of the filler can be 0.01 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the binder material.

[0053] The mass ratio of the rare earth aluminate phosphor to the binder material contained in the wavelength conversion layer can be, for example, 0.5 or more and 7 or less, preferably 0.8 or more, or can be 1.0 or more, and preferably 6 or less.

[0054] The average thickness of the wavelength conversion layer can be, for example, 50 μm or more and 200 μm or less, preferably 60 μm or more, or 70 μm or more, and 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 of the light-emitting device has a tendency to be further improved. The thickness of the wavelength conversion layer is calculated by subtracting the arithmetic mean of the thickness of the substrate from the arithmetic mean of the total thickness of the wavelength conversion layer and the substrate. The arithmetic mean of the total thickness of the wavelength conversion layer and the substrate and the arithmetic mean of the thickness of the substrate are calculated from the measured values at any 6 positions.

[0055] The wavelength conversion layer can have a substantially uniform thickness. The coefficient of variation of the thickness of the wavelength conversion layer can 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 can 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.

[0056] In one aspect, the wavelength conversion member can include: a disk-shaped substrate having a reflective surface, and a wavelength conversion layer disposed in a circular ring along the circumference of the substrate on the reflective surface of the substrate.

[0057] Light-emitting device

[0058] 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 a mixed-color light of the light from the light source and the light from the wavelength conversion member, and the wavelength conversion member is irradiated with the light from the light source. By including a wavelength conversion member having a specific structure, the light-emitting device can achieve good overall efficiency. The details of the wavelength conversion member constituting the light-emitting device are as described above.

[0059] The light-emitting device according to one aspect may further include a motor that rotates the wavelength conversion member. The wavelength conversion member is fixed to the rotating shaft of the motor and is configured to be rotatable by the motor.

[0060] Examples of the light source that irradiates the wavelength conversion member with light include a light-emitting element. The light-emitting element may be a semiconductor light-emitting element, a light-emitting diode, or a laser diode. The light-emitting element constituting the light source may be a single type or a combination of two or more types. Further, the light-emitting element constituting the light source may be one or a plurality of light-emitting elements.

[0061] The light source may have an emission peak wavelength in a wavelength range of, for example, 400 nm or more and 500 nm or less. The emission peak wavelength of the light source is preferably in 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 30 nm or less, for example.

[0062] As the light power density irradiated onto the wavelength conversion member, the output power of the light source may be, for example, 50 mW / mm 2 or more and 1000 mW / mm 2 or less, preferably 300 W / mm 2 or more, or may be 600 W / mm 2 or more, 800 W / mm 2 or less, or may be 700 W / mm 2 or less.

[0063] The light-emitting device may be configured as, for example, a projector described later. A high-output projector can be configured by using a light-emitting device showing good overall efficiency. The light-emitting device can be used not only as a light source device for a projector, but also, for example, as a light source for general lighting devices such as ceiling lights, spotlight, stadium lighting, studio lighting and other special lighting devices, vehicle lighting devices such as headlamps, projection devices such as head-up display devices; a light-emitting device for use as a light source in endoscope lamps, digital cameras, cameras such as mobile phones and smartphones, liquid crystal display devices such as personal computer (PC) monitors, laptop computers, televisions, mobile terminals (PDX), smartphones, tablet computers, mobile phones, etc.

[0064] Projector

[0065] The projector includes: the above light-emitting device, an image display system, and a projection optical system. In the projector, the light from the light source and the mixed light of the light from the light source that has been wavelength-converted by the wavelength conversion member are irradiated onto 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.

[0066] 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. A liquid crystal display screen, a digital micromirror device (DMD), etc. can be used in the image display system. The projection optical system converts the light emitted from the wavelength conversion member into an image through the image display system and projects it to the outside. The projection optical system includes a plurality of lenses and can perform magnification, reduction, focal length adjustment, etc. In addition to the above components, the projector also has components such as lenses and dichroic mirrors. Additionally, according to the design of the projector, mirrors, dichroic mirrors, lenses, prisms, etc. can be further included. Method for manufacturing rare earth aluminate phosphor

[0067] The method for manufacturing a rare earth aluminate phosphor includes: a preparation step of preparing a first rare earth aluminate, in which the first rare earth aluminate has the following composition: containing a first element M including at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 , cerium (Ce), aluminum (Al), oxygen atoms (O), and optionally containing or not containing a second element M including at least one selected from gallium (Ga) and scandium (Sc) according to need 2 , when the molar number of oxygen atoms is 12, the total molar number of the first element M 1 and cerium is 2.9 or more and 3.1 or less, and the total molar number of aluminum and the second element M 2 is 4.5 or more and 5.5 or less; 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 can be the rare earth aluminate phosphor as the target.

[0068] The second rare earth aluminate phosphor contained in the first heat-treated product obtained by heat-treating the first rare earth aluminate at a specific heat treatment temperature in a reducing atmosphere can achieve excellent luminous efficiency when constituting the wavelength conversion member. For example, it can be considered in the following way. By performing heat treatment in an appropriate reducing atmosphere, not only trivalent cerium (Ce 3+ ) that contributes to luminescence is generated, but also tetravalent cerium (Ce 4+ ) that does not directly contribute to luminescence is appropriately generated. Under high-density excitation, a part of the excited electrons are dissipated as heat, but due to Ce4+ Due to the existence of 4+ , a part of the electrons are recaptured, and Ce 4+ changes to Ce 3+ , which becomes conducive to luminescence. That is to say, it can be considered that the luminescence efficiency can be improved by Ce 4+ capturing a part of the lost electrons.

[0069] In the preparation process, a first rare earth aluminate with a specific composition is prepared. The first rare earth aluminate can be prepared by assignment or the like, or a first rare earth aluminate with a desired composition can be prepared by a conventional method. The manufacturing method of the first rare earth aluminate will be described later.

[0070] In the first heat treatment process, the prepared first rare earth aluminate is subjected 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. 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. In addition, the first heat treatment can be heat treatment carried out in an atmosphere with a reduced oxygen concentration, or can be, for example, heat treatment carried out under reduced pressure. The heat treatment in the presence of a carbon source can be implemented by, for example, using a closed container containing the first rare earth aluminate and a carbon source and performing heat treatment on the closed container. At this time, the first rare earth aluminate can be accommodated in an open container different from the carbon source, or can be accommodated in the same container as the carbon source. In addition, the heat treatment in the presence of a carbon source can also be implemented as follows: The first container containing the first rare earth aluminate is placed on the carbon source, and heat treatment is performed on the closed container formed by covering the first container and the carbon source with a second container. The heat treatment in a reducing atmosphere can be carried out by performing heat treatment together with the carbon source.

[0071] 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 polyolefins, polyvinyl alcohol, phenolic resins, and polyamide resins. The reducing atmosphere in the first heat treatment can contain an inert gas. Examples of the inert gas include rare gases such as nitrogen and argon. In addition, the first heat treatment can also be implemented by performing heat treatment on a closed container containing the first rare earth aluminate and a carbon source in the atmosphere. The amount of the carbon source used can be, for example, 1% by mass or more and 70% by mass or less, preferably 3% by mass or more, or can be 50% by mass or less, relative to the mass of the first rare earth aluminate.

[0072] The atmosphere containing a reducing gas may also 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, etc. In addition, examples of the inert gas include rare gases such as nitrogen gas and argon gas. When the atmosphere for heat treatment contains a reducing gas and an inert gas, the content ratio 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.

[0073] The heat treatment temperature in the first heat treatment step may be, for example, a temperature of 900°C or more and less than 1300°C, preferably 950°C or more, 1000°C or more, or 1050°C or more, and may be 1250°C or less, 1200°C or less, or 1150°C or less. When the temperature of the first heat treatment is within the above range, there is a tendency to improve the wheel efficiency. 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 may be 26 hours or less. Here, the heat treatment time refers to the time from reaching a given temperature to starting to cool down, and the same applies hereinafter. The first heat treatment step can be carried out using, for example, a tube furnace, a high-frequency electric furnace, a metal furnace, an atmosphere furnace, a gas pressurized furnace, etc.

[0074] Before the first heat treatment step, the method for manufacturing a rare earth aluminate phosphor may further include a second heat treatment step of subjecting the first rare earth aluminate to a second heat treatment in the presence of oxygen. By the second heat treatment, the wheel efficiency can be further improved.

[0075] The atmosphere for the second heat treatment may contain oxygen and an inert gas. The oxygen content in the second heat treatment atmosphere 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 can be carried out, for example, under the atmosphere.

[0076] The temperature of the second heat treatment may be, for example, 900°C or more and 1400°C or less, preferably 1000°C or more, or may be 1350°C or less. In addition, 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 more and 400°C or less, preferably 100°C or more, or may be 300°C or less. The time of the second heat treatment may be, for example, 2 hours or more and 10 hours or less, preferably 4 hours or more, or may be 8 hours or less.

[0077] When the method for manufacturing a rare earth aluminate phosphor includes a second heat treatment step, it is possible to cool to a given temperature after the second heat treatment step and continuously perform the first heat treatment step. Alternatively, it is also possible to cool to around room temperature after the second heat treatment step and then heat up to a given temperature to perform the first heat treatment step in two stages.

[0078] The method for manufacturing 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. Through the dispersion treatment, the particle size of the obtained rare earth aluminate phosphor tends to become 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 using a bead mill, a jet mill, a ball mill, a roller 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. With respect to the mass of the first heat-treated product, the content of the liquid medium in the mixture can be, for example, 10% by mass or more and 400% by mass or less, preferably 50% by mass or more, or can be 200% by mass or less.

[0079] When using a bead mill in the wet dispersion, examples of the material of the beads used include: alumina, zirconia, etc. In addition, the particle size of the beads can be, for example, 1 mm or more and 10 mm or less. The temperature of the wet dispersion can be, for example, 5°C or more and 40°C or less. The time for the dispersion treatment can be, for example, 2 hours or more and 50 hours or less.

[0080] The method for manufacturing a rare earth aluminate phosphor may include solid-liquid separation, drying treatment, classification treatment, etc. after the dispersion step. The solid-liquid separation of the dispersion can be carried out by, for example, filtration, suction filtration, pressure filtration, centrifugation, decantation, etc., which are commonly used in industry. The solid component recovered by the solid-liquid separation can be dried using devices commonly used in industry, such as a vacuum dryer, a hot air heating dryer, a conical dryer, a rotary evaporator, etc. The drying temperature can be, for example, 50°C or more and 200°C or less, preferably 80°C or more and 130°C or less. The drying time can be, for example, 0.5 hours or more and 200 hours or less, preferably 1 hour or more and 20 hours or less.

[0081] The method for manufacturing 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 subjected to the acid treatment step may be the first heat-treated product after wet dispersion treatment or the first heat-treated product before wet dispersion treatment. The acidic liquid medium used in the acid treatment step may include, for example, an aqueous liquid medium and an acid component. Examples of the acid component include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and hydrofluoric acid; and organic acids such as formic acid and acetic acid. The acid component contained in the liquid medium may be a single type or a combination of two or more types. The acidic liquid medium may contain at least water, and in addition to water, water-soluble organic solvents such as alcohols may be contained as needed. The content of the acid component in the acidic liquid medium may be, for example, 0.1% by mass or more and 40% by mass or less, preferably 5% by mass or more and 10% by mass or less. The pH of the acidic liquid medium may be, for example, 1.0 or more and 3.0 or less, preferably 1.2 or more, or may be 2.5 or less. The amount of the acidic liquid medium used for contacting the first heat-treated product may be, for example, 1% by mass or more and 30% by mass or less, preferably 5% by mass or more, or may be 20% by mass or less, relative to the mass of the first heat-treated product.

[0082] 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 an appropriate container. Stirring can be performed as needed at this time. The contact temperature between the first heat-treated product and the acidic liquid medium may be, for example, 5°C or more and 40°C or less. The contact time may be, for example, 0.1 hour or more and 10 hours or less.

[0083] The method for manufacturing a rare earth aluminate phosphor may include solid-liquid separation, washing treatment, drying treatment, classification treatment, etc. after the acid treatment step.

[0084] The method for manufacturing a rare earth aluminate phosphor may further include a synthesis step of manufacturing a 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, a first rare earth aluminate having a desired composition can be synthesized.

[0085] The raw material mixture contains: a first element M 1 source containing at least one selected from yttrium, lanthanum, lutetium, gadolinium, and terbium, a cerium source, an aluminum source, and optionally further contains or does not contain a second element M 2 source containing at least one selected from gallium and scandium according to need. 1 source, a cerium source, an aluminum source, and optionally further contains or does not contain a second element M 2 2 source.

[0086] As the first element M 1 1 source, cerium source, aluminum source, and the second element M 2 2As the source, metal compounds, simple substances, alloys, etc. each containing their respective metal elements can be cited. As the metal compound, oxides, metal salts, etc. can be cited. As the metal salt, for example, oxalates, carbonates, halides, nitrates, sulfates, etc. can be cited. The metal compound used as the raw material may be in the form of a hydrate.

[0087] As the first element M 1 source, specifically, Y 2 O 3 , La 2 O 3 , Lu 2 O 3 , Gd 2 O 3 , Tb 4 O 7 and other oxides; 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. As the cerium source, specifically, CeO 2 and other oxides; CeCl 3 , Ce 2 (SO 4 )3 metal salts such as. As the aluminum source, specifically, Al 2 O 3 oxides such as, AlCl 3 , Al(NO 3 ) 3 , Al 2 (SO 4 ) 3 metal salts such as. As the second element M 2 source, specifically, Ga 2 O 3 , Sc 2 O 3 oxides such as; GaCl 3 , Ga(NO 3 ) 3 , ScCl 3 , Sc(NO 3 ) 3 metal salts such as.

[0088] For example, when the total molar amount of the first element M 1 and cerium is 3, the raw material mixture may have a composition in which the total molar amount of aluminum and the second element M 2 is 4.5 or more and 5.5 or less, preferably 4.75 or more, or may have a composition of 5.25 or less. Relative to the total molar amount of the first element M 1 and cerium, the raw material mixture may have a composition in which the molar ratio of cerium is 0.002 or more and 0.018 or less, preferably 0.003 or more, or 0.004 or more, and further preferably 0.015 or less, 0.008 or less, or 0.006 or less. Relative to the total molar amount of aluminum and the second element M 2 , the raw material mixture may have a composition in which the molar ratio of 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 further preferably 0.2 or less, 0.1 or less, 0.05 or less, 0.02 or less, or 0.01 or less.

[0089] The raw material mixture may further contain a specific compound containing at least one element selected from barium (Ba), strontium (Sr), calcium (Ca), magnesium (Mg), and manganese (Mn). These specific compounds are compounds that can function as a flux in the synthesis process. By containing a flux in the raw material mixture, there are cases where the reaction between the raw materials is promoted and the solid-phase reaction is more likely to proceed uniformly. It is considered that the heat treatment temperature of the raw material mixture is almost the same as or higher than the liquid-phase formation temperature of the compound used as the flux, thereby promoting the solid-phase reaction.

[0090] The specific compound may be, for example, a halide, preferably at least one of a fluoride and a chloride, more preferably a fluoride. The specific compound may be, for example, barium fluoride. Due to the use of barium fluoride, it is considered that the garnet crystal structure of the rare earth aluminate is more stabilized and the composition of the garnet crystal structure is more easily formed. 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 may be 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 further promoted, the solid-phase reaction proceeds more uniformly, and there is a tendency to easily obtain the first rare earth aluminate having the target composition.

[0091] The raw material mixture can be obtained by weighing each raw material to obtain the desired prepared composition and then mixing. As the mixing method, it can be, for example, pulverization and mixing using a dry pulverizer such as a ball mill, a vibration mill, a hammer mill, a roll mill, a jet mill, etc., or pulverization and mixing using a mortar and a pestle, etc., or mixing using a mixer such as a ribbon mixer, a Henschel mixer, a V-type blender, etc., or pulverization and mixing can be performed by using both a dry pulverizer and a mixer at the same time. In addition, the mixing can be dry mixing or wet mixing with the addition of a solvent or the like. The mixing is preferably dry mixing. Compared with wet mixing, dry mixing can further shorten the process time and has a tendency to be beneficial to improving productivity.

[0092] The heat treatment of the raw material mixture can be carried out by disposing the raw material mixture in a container such as a crucible or a boat. As the material of the container, the following can be cited: carbon materials such as graphite, boron nitride (BN), alumina (bauxite), tungsten (W), molybdenum (Mo), etc.

[0093] The temperature of the heat treatment of the raw material mixture may be, for example, 1400 °C or more and 1800 °C or less, preferably 1450 °C or more, 1500 °C or more, or 1600 °C or more, and preferably 1700 °C or less, 1650 °C or less. When the temperature of the heat treatment is within the above range, the stability of the crystal structure of the first rare earth aluminate has a tendency to be further improved. The heat treatment time may be, for example, 1 hour or more and 20 hours or less, preferably 3 hours or more, 5 hours or more, or 8 hours or more, and preferably 15 hours or less, or 12 hours or less. The heat treatment can be carried out using, for example, an electric furnace, a gas furnace, etc.

[0094] The atmosphere for heat treatment can be, for example, a reducing atmosphere. Regarding the reducing atmosphere, as described above. In a reducing atmosphere, the reactivity of the raw material mixture increases, and the desired first rare earth aluminate can be obtained by heat treatment under atmospheric pressure without pressurization. In addition, by heat-treating the raw material mixture in a reducing atmosphere, tetravalent Ce (Ce 4+ ) is reduced to trivalent Ce (Ce 3+ ), and the proportion of trivalent Ce contributing to luminescence becomes larger, and there is a tendency to obtain the first rare earth aluminate.

[0095] The synthesis process may include, as needed after heat treatment, crushing / grinding treatment, washing treatment, drying treatment, classification treatment, etc.

[0096] The invention of the present disclosure may include, for example, the following modes.

[0097] [1] A rare earth aluminate phosphor having the following composition:

[0098] The phosphor contains: a first element M containing at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 ,

[0099] cerium (Ce),

[0100] aluminum (Al),

[0101] oxygen atoms (O), and,

[0102] optionally contains or does not contain a second element M containing at least one selected from gallium (Ga) and scandium (Sc) 2 ,

[0103] wherein, 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.

[0104] In the reflection spectrum, the ratio of the reflectance at a wavelength of 280 nm to the reflectance at a wavelength of 380 nm of the phosphor is 0.33 or more and 0.76 or less.

[0105] [2] The rare earth aluminate phosphor according to [1], wherein

[0106] 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.

[0107] [3] The rare earth aluminate phosphor according to [1] or [2], having the following composition:

[0108] The molar number of cerium relative to the first element M 1 and the total molar number of cerium is 0.002 or more and 0.018 or less,

[0109] The second element M 2 The molar number of relative to the total molar number of aluminum and the second element M 2 is 0.6 or less.

[0110] [4] The rare earth aluminate phosphor according to any one of [1] to [3], which has a composition represented by the following formula (1):

[0111] (M 1 (1-p) Ce p ) q (Al (1-r) M 2 r ) s O 12 (1)

[0112] In formula (1), M 1 contains at least one selected from Y, La, Lu, Gd, and Tb, and M 2 contains at least one selected from Ga and Sc, and 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.

[0113] [5] The rare earth aluminate phosphor according to any one of [1] to [4], wherein

[0114] The number average particle diameter is 10 μm or more and 60 μm or less.

[0115] [6] The rare earth aluminate phosphor according to any one of [1] to [5], wherein

[0116] 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.

[0117] [7] A wavelength conversion member, which includes:

[0118] A substrate,

[0119] An adhesive material disposed on the substrate, and

[0120] A wavelength conversion layer that contains the rare earth aluminate phosphor according to any one of [1] to [6].

[0121] [8] The wavelength conversion member according to [7], wherein,

[0122] With respect to 100 parts by mass of the adhesive material, 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.

[0123] [9] The wavelength conversion member according to [7] or [8], wherein,

[0124] The average thickness of the wavelength conversion layer is 50 μm or more and 200 μm or less.

[0125]

[10] A light-emitting device, comprising:

[0126] The wavelength conversion member according to any one of [7] to [9], and

[0127] A light source that irradiates light onto the wavelength conversion member.

[0128]

[11] The light-emitting device according to

[10] , wherein,

[0129] The optical power density of the light irradiated by the light source onto the wavelength conversion member is 50 mW / mm 2 or more and 1000 mW / mm 2 or less.

[0130]

[12] A projector, comprising:

[0131] The light-emitting device according to

[10] or

[11] ,

[0132] An image display system, and

[0133] A projection optical system.

[0134]

[13] A method for manufacturing a rare earth aluminate phosphor, the method comprising:

[0135] Preparing a first rare earth aluminate, and

[0136] 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;

[0137] wherein, the first rare earth aluminate has the following composition:

[0138] The first rare earth aluminate contains: a first element M containing at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd), and terbium (Tb) 1 ,

[0139] cerium (Ce),

[0140] aluminum (Al),

[0141] oxygen atoms (O), and,

[0142] optionally includes or does not include a second element M containing at least one selected from gallium (Ga) and scandium (Sc) 2 ,

[0143] wherein, 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.

[0144]

[14] The manufacturing method according to

[13] , wherein,

[0145] the first heat treatment is performed in the presence of a carbon source.

[0146]

[15] The manufacturing method according to

[13] or

[14] , further comprising:

[0147] before performing the first heat treatment, a second heat treatment is performed on the first rare earth aluminate in the presence of oxygen.

[0148]

[16] The manufacturing method according to

[15] , wherein,

[0149] the temperature of the second heat treatment is higher than the temperature of the first heat treatment.

[0150]

[17] The manufacturing method according to any one of

[13] to

[16] , further comprising:

[0151] performing wet dispersion on the first heat-treated product.

[0152]

[18] The manufacturing method according to any one of

[13] to

[17] , further comprising:

[0153] bringing the first heat-treated product into contact with an acidic liquid medium.

[0154] Examples

[0155] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0156] Reference Example 1

[0157] Measure 1669.2 g (4.194 moles) of lutetium oxide (Lu 2 O 3 ), 1669.2 g (4.194 moles) of cerium oxide (CeO 2) 12.12 g (0.07046 mol), alumina (Al 2 O 3 ) 718.7 g (7.046 mol), barium fluoride (BaF 2 ) 144 g (0.8214 mol), gallium oxide (Ga 2 O 3 ) 12 g (0.06403 mol) were placed in a polyethylene container together with alumina balls and mixed by a ball mill for 4 hours to obtain a raw material mixture. The raw material mixture was filled into an alumina crucible and placed on a plate covered with activated carbon. A large alumina crucible was covered in such a way as to cover the alumina crucible filled with the raw material mixture. Heat treatment was carried out at 1625 °C for 10 hours using an electric furnace to obtain the first rare earth aluminate.

[0158] Example 1

[0159] 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. Then, the alumina crucible was placed on a plate covered with activated carbon, and a large alumina crucible was covered in such a way as to cover the alumina crucible filled with the first rare earth aluminate, and heat treatment was carried out at the first heat treatment temperature of 1100 °C for 6 hours to obtain the first heat-treated product.

[0160] The following wet dispersion treatment and acid treatment were carried out on the obtained first heat-treated product 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 dispersion treatment was carried out at room temperature (25 °C) for 15 hours. Coarse particles were removed by a sieve. Acid cleaning was carried out using hydrochloric acid, sedimentation classification was carried out, and fine particles were removed. Drying treatment was carried out to obtain the rare earth aluminate phosphor of Example 1.

[0161] The obtained first rare earth aluminate was analyzed by high-frequency inductively coupled plasma (ICP) emission analysis, and the first rare earth aluminate had the following composition.

[0162] Lu 2.986 Ce 0.014 Al 4.952 Ga 0.036 O 12

[0163] Example 2

[0164] Heat treatment in an air atmosphere was not carried out, and otherwise, the same operations as in Example 1 were carried out to obtain the rare earth aluminate phosphor of Example 2.

[0165] Example 3

[0166] The first heat treatment temperature was changed to 1000 °C, and otherwise, the operation was the same as in Example 2, and the rare earth aluminate phosphor of Example 3 was obtained.

[0167] Comparative Example 1

[0168] The first heat treatment temperature was changed to 1400 °C, and otherwise, the operation was the same as in Example 2, and the rare earth aluminate phosphor of Comparative Example 1 was obtained.

[0169] Comparative Example 2

[0170] The first heat treatment temperature was changed to 1300 °C, and otherwise, the operation was the same as in Example 2, and the rare earth aluminate phosphor of Comparative Example 2 was obtained.

[0171] Comparative Example 3

[0172] 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. The obtained heat-treated product was wet-dispersed and acid-treated, and otherwise, the operation was the same as in Example 1, and the rare earth aluminate phosphor of Comparative Example 3 was obtained.

[0173] Comparative Example 4

[0174] The heat treatment temperature was changed to 1300 °C, and otherwise, the operation was the same as in Comparative Example 3, and the rare earth aluminate phosphor of Comparative Example 4 was obtained.

[0175] Evaluation

[0176] For the rare earth aluminate phosphors obtained above, the following evaluations were carried out.

[0177] Number average particle diameter

[0178] 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.

[0179] Luminescence characteristics

[0180] For the obtained rare earth aluminate phosphors, using a quantum efficiency measurement system (QE-2000, manufactured by Otsuka Electronics Co., Ltd.), excitation light with a peak emission wavelength of 450 nm was irradiated, and the emission spectrum was measured. 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 peak emission wavelength, the peak emission wavelength (nm), and the full width at half maximum (FWHM) (nm) of the emission spectrum were obtained. Taking the emission intensity of the phosphor of the comparative example as 100%, the relative emission intensity (%) was calculated as the relative value of the emission intensity of each phosphor.

[0181] Reflection spectrum

[0182] For the rare earth aluminate phosphors obtained from Example 1 and Comparative Example 1, using a fluorescence spectrophotometer (F-4500, manufactured by Hitachi High-Technologies Corporation), at room temperature (25 ± 5 °C), light from an iodine tungsten lamp as an excitation source was irradiated onto each phosphor as a sample, and the wavelengths of the spectrometers on the excitation side and the phosphor side were scanned to measure the reflection spectrum of each phosphor. The reflection spectrum with a reflectance of 100% for calcium hydrogen phosphate (CaHPO 4 ) is shown in Figure 1 .

[0183] Reflectance

[0184] For the obtained rare earth aluminate phosphors, using a spectrofluorometer (F-4500, manufactured by Hitachi High-Technologies Corporation), at room temperature (25 ± 5 °C), light from an iodine tungsten lamp as an excitation source was irradiated onto each phosphor as a sample, and by scanning the wavelengths of the spectrometers on the excitation side and the phosphor side, the reflectance at a wavelength of 280 nm and the reflectance at a wavelength of 380 nm were measured. It should be noted that the reflectance of calcium hydrogen phosphate (CaHPO 4 ) as a reference was set to 100%.

[0185] 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 Figure 2 .

[0186] Fluorescence lifetime

[0187] Each phosphor was irradiated with excitation light having a peak emission wavelength of 280 nm or 442 nm, and using a small fluorescence lifetime device (Quantaurus-Tau, manufactured by Hamamatsu Photonics K.K.), the change over time in the fluorescence intensity of each phosphor was measured starting from when the irradiation of the excitation light was cut off. The fluorescence intensity at the time of cutting off the excitation light was set to 100%, and the time when the fluorescence intensity became 1 / e of that at the time of cutting off the excitation light was measured as the fluorescence lifetime. The results are shown in Table 1. A "-" in Table 1 indicates inapplicable or not measured.

[0188] [Table 1]

[0189]

[0190] Fabrication of wavelength conversion member

[0191] As the substrate, a disk-shaped substrate made of a metal containing aluminum, having a diameter of 65 mm and a thickness of 0.50 mm, was prepared. The specular reflectance of the reflective surface of the substrate for light at 450 nm was 98.2%.

[0192] 500 parts by mass of each of the above-obtained rare earth aluminate phosphors were respectively added to 100 parts by mass of dimethyl silicone resin, and the mixture was mixed using a vacuum degassing mixer to obtain a phosphor composition. The obtained phosphor composition was attached to the substrate by screen printing to form a phosphor composition layer. Thereafter, 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, and respective wavelength conversion members were obtained.

[0193] Relative luminous efficiency

[0194] For each of the obtained wavelength conversion members, the relative luminous efficiency (%) was determined as follows. Through a dichroic mirror, the wavelength conversion member was irradiated with laser light emitted from a laser diode having a wavelength of 450 nm at an intensity of 90 W, and the incident light was made to enter the wavelength conversion member such that the optical path of the incident light was Φ1 mm. The emission beam of the light emitted from the same surface as the surface on which the laser light was incident was separated by the 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 incident light by the intensity of the emitted 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 (%) of the luminous efficiency of the wavelength conversion members obtained using the rare earth aluminate phosphors of each Example and Comparative Example was determined. The results are shown in Table 2.

[0195] [Table 2]

[0196]

Claims

1. A rare earth aluminate phosphor, the phosphor having the following composition: The phosphor contains a first element M 1 , cerium (Ce), aluminum (Al) and oxygen atoms (O), The first element M 1 contains at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd) and terbium (Tb), The phosphor may or may not contain a second element M. 2 , the second element M 2 contains at least one selected from gallium (Ga) and scandium (Sc), Among them, when the number of moles of oxygen atoms is 12, the first element M 1 The total molar number of aluminum and the second element M is 2.9 or more and 3.1 or less. 2 The total number of moles is 4.5 or more and 5.5 or less, The phosphor has a ratio of a reflectivity at a wavelength of 280 nm to a reflectivity at a wavelength of 380 nm in a reflection spectrum of 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 rare earth aluminate phosphor according to claim 1, wherein the phosphor has the following composition: The molar number of cerium relative to the first element M 1 The ratio of the total molar number of cerium to that of cerium is 0.002 or more and 0.018 or less, The second element M 2 The number of moles relative to the aluminum and the second element M 2 The ratio of the total molar number of is 0.6 or less.

4. The rare earth aluminate phosphor according to claim 1, which has a composition represented by the following formula (1): (M 1 (1-p) What p ) q (Al (1-r) M 2 r ) s A 12 (1) In formula (1), M 1 Contains at least one selected from Y, La, Lu, Gd and Tb, M 2 It contains at least one selected from Ga and Sc, and 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, wherein The number average particle size is 10 μm or more and 60 μm or less.

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

7. A wavelength conversion component, comprising: substrate, a bonding material disposed on the substrate, and A wavelength conversion layer comprising 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 relative to 100 parts by mass of the binder.

9. The wavelength conversion member according to claim 7, wherein: The wavelength conversion layer has an average thickness of 50 μm or more and 200 μm or less.

10. A light emitting device, comprising: The wavelength conversion member according to any one of claims 7 to 9, and A light source irradiates light toward the wavelength conversion member.

11. The light emitting device according to claim 10, wherein: The light power density of the light source irradiating the wavelength conversion component is 50 mW / mm 2 Above and 1000mW / mm 2 the following.

12. A projector, comprising: The light emitting device according to claim 10, Image display system, and Projection optical system.

13. A method for producing a rare earth aluminate phosphor, the method comprising: preparing a first rare earth aluminate, and The first rare earth aluminate is subjected 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. Wherein, the first rare earth aluminate has the following composition: The first rare earth aluminate contains a first element M 1 , cerium (Ce), aluminum (Al) and oxygen atoms (O), The first element M 1 contains at least one selected from yttrium (Y), lanthanum (La), lutetium (Lu), gadolinium (Gd) and terbium (Tb), According to the need, the phosphor may or may not contain the second element M. 2 , the second element M 2 contains at least one selected from gallium (Ga) and scandium (Sc), Among them, when the number of moles of oxygen atoms is 12, the first element M 1 The total molar number of aluminum and the second element M is 2.9 or more and 3.1 or less. 2 The total molar number of is 4.5 or more and 5.5 or less.

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 comprising: Prior to the first heat treatment, the first rare earth aluminate is subjected to a second heat treatment in the presence of oxygen.

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 comprising: The first heat-treated product is wet dispersed.

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

Images