JP2022163451A - Phosphor and light-emitting device including the same - Google Patents

Abstract

To provide a phosphor that shows little decrease in luminance due to brightness saturation under a high-power light source and has excellent emission properties in a blue-green wavelength range.SOLUTION: A phosphor comprises a material having a garnet type crystal structure represented by the following formula (1) Lu3-x-zCezErxAl5-yAyO12 (1), where A is one of Ga, Mg, and Si, with 0<x≤2.85, 0.25≤y and 0<z≤0.12.SELECTED DRAWING: None

Description

The present invention relates to a phosphor that absorbs bluish excitation light and emits blue-green fluorescence, and a light-emitting device using this phosphor.

Semiconductor light-emitting elements such as light-emitting diodes (hereinafter referred to as LEDs) have the advantages of being small, consuming less power, and capable of stably emitting light with high luminance. BACKGROUND ART Many lighting fixtures using light-emitting devices composed of LEDs that emit white light are used. As an LED that emits white light, for example, a combination of a blue LED and a Ce-activated YAG-based yellow phosphor represented by a composition formula of Y ₃ Al ₅ O ₁₂ :Ce is known.

In the light-emitting device having the above configuration, a material obtained by mixing Ce-activated YAG phosphor and resin is applied to the element of the blue LED. realizing the light. However, this configuration has a problem that it develops a pale color due to the emission characteristics of the Ce-activated YAG phosphor and lacks color rendering properties. As a solution to this problem, in addition to blue LEDs and yellow phosphors, a technique is also used in which a plurality of green phosphors and red phosphors are combined to emit white light. With such a configuration, the short wavelengths are compensated for, and light emission containing more visible light components can be obtained.

On the other hand, in recent years, needs for color rendering properties have diversified depending on the application, and phosphors for more finely adjusting chromaticity are desired. One of them is a demand to improve the color rendering properties by adding a blue-green phosphor in addition to the yellow phosphor, the green phosphor, and the red phosphor. This applies not only to LED lighting, but also to light sources using laser diodes (LD) and phosphor wheels used in projectors and the like.

As a general blue-green phosphor, for example, Patent Document 1 discloses a phosphor capable of emitting light in the blue-green region with an emission wavelength of about 500 nm by combining a blue LED and an Eu-activated SiAlON phosphor. It is

JP-A-2005-112922

However, the phosphor of Patent Document 1 has the following problems.
For example, when applying a high-output excitation light source such as a blue LD as an excitation light source to realize a high-luminance, high-color-rendering light source, the phosphor described in Patent Document 1 activates Eu, which has a long emission life as the emission center. is doing. Therefore, under a high output light source, the emission luminance cannot be increased due to luminance saturation, and it is difficult to increase the output. Luminance saturation is a phenomenon in which the luminance of light emitted from a phosphor is not proportional to the output of a light source. In the above-mentioned Ce-activated YAG-based phosphor, luminance saturation is less likely to occur because Ce has a shorter emission life than Eu. In addition, the mother phase in which Eu is activated in Patent Document 1 is an oxynitride phosphor, and the process is complicated, such as the need for management of the manufacturing process, especially the baking process in which the synthesis reaction is performed, and a large manufacturing apparatus. Become. For example, when Si ₃ N ₄ is used as a raw material, it is thermally decomposed at a high temperature, so a furnace with a high-pressure environment is required during firing, making it difficult to ensure stable quality. In addition, firing may be performed in an atmosphere such as ammonia, which may be a dangerous process. On the other hand, oxide phosphors do not require a high-pressure environment and can be synthesized in the air, depending on the materials used. For these reasons, a new Ce-activated oxide phosphor having an emission peak in the blue-green region is desired.

The present invention is intended to solve such conventional problems. It is an object of the present invention to provide a Ce-activated oxide phosphor exhibiting below 525 nm.

The phosphor according to one aspect of the present disclosure has the following composition formula (1)
_{Lu3 -xzCezErxAl5- yAyO12 ( 1 )}
including a material having a garnet-type crystal structure represented by
A is any one of Ga, Mg, and Si;
0<x≦2.85, 0.25≦y and
0<z≦0.12.

Further, a light-emitting device according to the present invention includes the phosphor, a light source having an emission peak wavelength of 400 nm or more and 450 nm or less,
It has

Since the phosphor according to the present invention has an emission peak wavelength of 480 nm or more and less than 525 nm, it exhibits high color rendering properties in the blue-green wavelength region within the visible light region. In addition, since Ce is used as the luminescence central element, there is little luminance saturation under irradiation with a high-output light source. Therefore, in combination with a light source that emits blue light having an emission peak wavelength of 450 nm, for example, a light-emitting device with high luminance and high color rendering can be obtained. In addition, since an oxide is used for the mother phase that activates Ce, a phosphor with stable quality can be provided without adopting a complicated process.

1 is a schematic diagram of a crystal structure of a mother crystal of a phosphor according to Embodiment 1. FIG. 4 is a diagram showing a composition range in which the emission peak wavelength of the phosphor according to Embodiment 1 is 480 nm or more and less than 525 nm; FIG. 1 is a schematic cross-sectional view showing a cross-sectional configuration of an LED light emitting device according to Embodiment 1; FIG. 1 is a schematic cross-sectional view showing a cross-sectional configuration of an LD light emitting device according to Embodiment 1; FIG. 5 is a diagram showing a composition range in which the emission peak wavelength of the phosphor according to Embodiment 2 is 480 nm or more and less than 525 nm; FIG. FIG. 10 is a diagram showing a composition range in which the emission peak wavelength of the phosphor according to Embodiment 3 is 480 nm or more and less than 525 nm; A list of the values of x, y, and z in the composition formula (2) and the emission peak wavelength of the phosphor material powders of Examples 1-1 to 1-23 and Comparative Examples 1-1 to 1-3 Table 1 shows. A list of the values of x, y, and z in the composition formula (3) and the emission peak wavelength of the phosphor material powders of Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-5 Table 2 shows. A list of x, y, z values and emission peak wavelengths of composition formula (4) in the phosphor material powders of Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-5 Table 3 is shown.

The phosphor according to the first aspect has a garnet-type crystal structure represented by the following composition formula (1) Lu _3-xz Ce _z Er _x Al _5-y A _y O ₁₂ (1) A is one of Ga, Mg, Si, 0<x≦2.85, 0.25≦y, and 0<z≦0.12.

In the phosphor according to the second aspect, in the first aspect, A is Ga, 0.15 ≤ x ≤ 2.85, 0.25 ≤ y ≤ 4.75, and y ≥ -3.75 x + 3 0.06.

A phosphor according to a third aspect is the first aspect, wherein A is Mg, 0.15≦x≦2.85, 0.25≦y≦1.25, and y≦0.56x+0. 42 may be used.

In a phosphor according to a fourth aspect, in the first aspect, A may be Si, and 1.5≦x≦2.85 and 0.25≦y≦0.5.

A light-emitting device according to a fifth aspect includes the phosphor according to any one of the first to fourth aspects, and a light source having an emission peak wavelength of 400 nm or more and 450 nm or less.

Phosphors and manufacturing methods thereof according to embodiments of the present disclosure will be described below with reference to the drawings. In addition, the same code|symbol is attached|subjected about the component which is common in each figure, and those description is abbreviate|omitted suitably.
First, the features of the phosphor according to the present disclosure that are common to each embodiment will be described.

The optical properties of the phosphor are determined by the mother crystal and the type of luminescent center. For example, Lu ₃ Al ₅ O ₁₂ :Ce, which is generally known as a green phosphor, is a crystal with a garnet structure belonging to the cubic system as a mother crystal, and the luminescence center is Ce. FIG. 1 shows a schematic diagram of this garnet type crystal 1 . The cations entering Lu site 2 and Al site 3 are coordinated with oxygen ions at O site 4. Lu site 2 is dodecahedral coordination, and Al site 3 is octahedral coordination. There are two types: tetrahedral coordination. In Embodiment 1 as well, the mother crystal is a Lu ₃ Al ₅ O ₁₂ crystal having a garnet structure, part of the Lu site 2 in FIG. It is a phosphor in which the part is further substituted with another element. Ce, which serves as the luminescence center, is not shown in the figure because the amount of Ce added as a whole is very small and does not exist in all crystal lattices. By substituting the Lu site 2 and part of the Al site 3, the crystal field around Ce, which is the emission center, changes. Then, the bandgap of Ce increases as the crystal field around Ce changes, and the emission wavelength shifts to the shorter wavelength side.

A common element in each of these embodiments can be represented by the following compositional formula (1).
The phosphor according to the present disclosure is
_{Lu3 -xzCezErxAl5- yAyO12 ( 1 )}
including a material having a garnet-type crystal structure represented by
A is any one of Ga, Mg, and Si;
0<x≦2.85, 0.25≦y and
It is characterized by 0<z≦0.12.
The reason for 0<x is that when the composition ratio of Er substituting Lu site 2 is 0, the effect of the crystal field on Ce, which is the light-emitting element shown above, is reduced, and the effect on the emission peak wavelength is also reduced. It's for.
The reason for x≦2.85 is that if the composition ratio of Er substituting the Lu site 2 is larger than 2.85, it becomes thermally unstable. Specifically, the Lu ₃ Al ₅ O ₁₂ crystal is considered to be a phosphor in which the phenomenon of temperature quenching, in which the emission luminance decreases with temperature rise, is relatively unlikely to occur. is likely to occur.
The reason why 0.25≦y is that when the composition ratio of the element A substituting the Al site 3 is less than 0.25, the effect of the crystal field on Ce, which is the light-emitting element shown above, becomes small, and the light-emitting peak wavelength This is because the effect on the
Also, 0<z≦0.12 is because the value of z is greater than 0 because Ce must be included in order to obtain light emission. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. There is no particular limitation on the maximum value of z as long as the phosphor can emit light. However, when the value of z becomes too large, the emission intensity decreases due to concentration quenching. Therefore, by setting the value of z to 0.12 or less, it is possible to suppress the decrease in emission intensity. Also, the value of z is desirably 0.1 or less from the viewpoint of increasing the emission intensity.

(Embodiment 1)
<Phosphor>
The phosphor according to Embodiment 1 is
The following compositional formula (2)
_{Lu3 -xzCezErxAl5- yGayO12 ( 2 )}
including a material having a garnet-type crystal structure represented by
x, y, and z in formula (2) are the composition ratio of Er, the composition ratio of Ga, and the composition ratio of Ce, respectively;
x and y simultaneously satisfy 0.15 ≤ x ≤ 2.85, 0.25 ≤ y ≤ 4.75 and y ≥ -3.75 x + 3.06, and z is in the range of 0 < z ≤ 0.12 be.

In the compositional formula (2), the value of z is greater than 0 because Ce must be included in order to obtain light emission. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. There is no particular limitation on the maximum value of z as long as the phosphor can emit light. However, when the value of z becomes too large, the emission intensity decreases due to concentration quenching. Therefore, by setting the value of z to 0.12 or less, it is possible to suppress the decrease in emission intensity. Also, the value of z is desirably 0.1 or less from the viewpoint of increasing the emission intensity.

<Manufacturing method of phosphor>
A method for manufacturing the phosphor material according to Embodiment 1 will be described below.
(1) First, raw material powder is prepared. Lutetium (Lu), erbium (Er), cerium (Ce), aluminum (Al), and gallium (Ga) are prepared as raw materials, and lutetium oxide, erbium oxide, cerium oxide, aluminum oxide, and gallium oxide are prepared as raw materials. . Materials other than these oxides can also be metal salt compounds such as carbonates.
(2) Next, weigh out predetermined amounts of these raw material powders and mix them thoroughly. The mixing method may be wet mixing in solution or dry mixing of dry powders. For mixing, industrially used ball mills, medium stirring mills, planetary mills, vibrating mills, jet mills, stirrers and the like can be used. Barium fluoride (BaF ₂ ) or strontium fluoride (SrF ₂ ) can be mixed as a flux corresponding to 0.1 wt % to 10 wt % of the mixed powder. Flux melts during firing and has the effect of promoting diffusion of each raw material and increasing reactivity.
(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for sintering. For example, the mixed powder is placed in an alumina crucible and heated together with the alumina crucible at 1200° C. or higher and 1700° C. or lower for 1 hour or more and 12 hours or less. After sintering, the powder is cooled, pulverized, and subjected to flux cleaning with an acid to obtain powder of the phosphor material.

<Evaluation of light emission characteristics>
The emission spectra of the phosphor material powders of Examples 1-1 to 1-23 and Comparative Examples 1-1 to 1-3 are measured using a spectrofluorophotometer using an integrating sphere. By setting the synthesized phosphor material powder at a predetermined position in the integrating sphere, irradiating the phosphor material powder with blue light emitted from a blue LED light source attached to the measuring device, and measuring the emission spectrum, Obtain the emission peak wavelength.

(criterion)
In the emission spectrum, those with an emission peak wavelength of 480 nm or more and less than 525 nm are evaluated as having excellent emission characteristics in the blue-green region, and those with an emission peak wavelength of 525 nm or more are evaluated as having insufficient emission characteristics in the blue-green region. x as a thing.

A list of the values of x, y, and z in the composition formula (2) and the emission peak wavelength of the phosphor material powders of Examples 1-1 to 1-23 and Comparative Examples 1-1 to 1-3 It is shown in Table 1 of FIG.

As shown in Table 1 of FIG. 7, by adjusting the composition ratio of Er and Ga, the emission peak wavelengths of Examples 1-1 to 1-23 were 480 nm or more and less than 525 nm, and all judgments were good. becomes. This is because by substituting Er at Lu site 2 and Ga at Al site 3, the influence as a crystal field that can be exerted on Ce, which is a light-emitting ion, has changed compared to the Lu ₃ Al ₅ O ₁₂ crystal without substitution. It is considered to be
The emission peak wavelength of Comparative Examples 1-1 to 1-3 is 525 nm or more, and the judgment is x.

FIG. 2 is a diagram showing the relationship between the Er composition ratio and the Ga composition ratio at which the emission peak wavelength of the phosphor according to Embodiment 1 is 480 nm or more and less than 525 nm. The horizontal axis is the Er composition ratio, which corresponds to x in the composition formula (2). The vertical axis is the Ga composition ratio, which corresponds to y in the composition formula (2). ◯ represents the portions where the emission peak wavelength is 480 nm or more and less than 525 nm in Examples 1-1 to 1-23. The X portion represents the portion where the emission peak wavelength is 525 nm or more in Comparative Examples 1-1 to 1-3. As shown in FIG. 2, in the relationship between the Er composition ratio and the Ga composition ratio, there is a boundary where the emission peak wavelength of the phosphor is 480 nm or more and less than 525 nm. Obtaining an approximate straight line along this boundary reveals that x≧0.15, x≦2.85, y≧0.25, y≦4.75, and y≧−3.75x+3.06. . That is, if the Er composition ratio and the Ga composition ratio are within the solid line area surrounded by the approximate straight line in FIG. 2, the emission peak wavelength is 480 nm or more and less than 525 nm. That is, the compositional formula (2)
_{Lu3 -xzCezErxAl5- yGayO12 ( 2 )}
x, y, and z in formula (2) are the composition ratio of Er, the composition ratio of Ga, and the composition ratio of Ce, respectively, and x and y are If 0.15 ≤ x ≤ 2.85, 0.25 ≤ y ≤ 4.75 and y ≥ -3.75 x + 3.06 are satisfied at the same time, and z is in the range of 0 < z ≤ 0.12, the emission peak The wavelength is 480 nm or more and less than 525 nm.

Here, the values of z in Table 1 and FIG. 2 are all fixed at 0.09. Since Ce is an element that serves as an emission center, it has a large effect on the emission luminance, but has a small effect on the emission peak wavelength. Similar results are obtained.

<Light emitting device>
As an example of the light-emitting device of the present disclosure, FIG. 3 illustrates an LED light-emitting device including a phosphor represented by the compositional formula (2) and an LED element as a light source. 3 is a schematic cross-sectional view showing the cross-sectional configuration of the LED light emitting device according to Embodiment 1. FIG. As shown in FIG. 3, the LED light emitting device 10 has an LED element 11 fixed on a support 12 via solder 13 so that the emission surface does not come into contact with the support 12 . Furthermore, the LED element 11 is electrically connected to an electrode 15 arranged on the support 12 by a bonding wire 14 . Further, the LED element 11 is covered with an LED wavelength conversion member 16, and the LED wavelength conversion member 16 includes, in addition to the LED encapsulant 17 and the blue-green phosphor 18, a green phosphor 19, a yellow phosphor 20, A red phosphor 21 is included.

For the LED element 11, for example, one that emits light in the ultraviolet to blue region and has an emission spectrum peak at a wavelength of 400 nm or more and 450 nm or less is used.

In this embodiment, since the LED light-emitting device 10 has a surface-mountable structure, the support 12 is a substrate. For example, a substrate having high thermal conductivity can be used as the support 12 so that the heat generated by the LED element 11 can be efficiently radiated to the outside. For example, a ceramic substrate made of alumina, aluminum nitride, or the like can be used as the support 12 .

A silicone resin is used for the LED sealing body 17 in the LED wavelength conversion member 16 . The silicone resin contains, for example, dimethylsilicone, which is highly resistant to discoloration. Methylphenyl silicone or the like with high heat resistance can also be used as the silicone resin. The silicone resin may be a homopolymer having a main skeleton defined by one type of chemical formula with a siloxane bond. It may also be a copolymer containing structural units having siloxane bonds defined by two or more types of chemical formulas, or an alloy of two or more types of silicone polymers.

The phosphor in the LED wavelength conversion member 16 wavelength-converts the light emitted from the LED element 11 into light with a longer wavelength. The phosphors contained in the LED wavelength conversion member 16 include all of the green phosphor 19, the yellow phosphor 20, and the red phosphor 21 in addition to the blue-green phosphor 18 in this embodiment. At least one phosphor other than the body 18 may be mixed. As the blue-green phosphor 18, the phosphor of Embodiment 1 can be used. As the green phosphor 19, for example, Ca ₃ SiO _{4 Cl2} :Eu, β-SiAlON:Eu, or the like can be used. As the yellow phosphor 20, for example, Y ₃ Al ₅ O ₁₂ :Ce, α-SiAlON:Eu, or the like can be used. As the red phosphor 21, for example, CaAlSiN ₃ :Eu or the like can be used.

In particular, FIG. 3 describes a case where the LED wavelength conversion member 16 is formed by mixing four types of green phosphor 19, yellow phosphor 20, and red phosphor 21 in addition to the blue-green phosphor 18. . The mixing ratio of the four phosphors can be appropriately adjusted according to the desired color tone of white light, the emission intensity of each phosphor, and the like. In addition to the blue-green phosphor 18, the four phosphors of the green phosphor 19, the yellow phosphor 20, and the red phosphor 21 are, for example, 3 parts by weight or more and 70 parts by weight with respect to 100 parts by weight of the sealing body. It is contained in the LED sealing body 17 at the following ratios. If the content is less than 3 parts by weight, sufficient intensity of fluorescence cannot be obtained, and it may not be possible to realize the LED light emitting device 10 that emits light of a desired wavelength. The weight ratio of the four types of phosphors can be appropriately determined according to the desired color tone of white light and the emission intensity of each phosphor.

By combining the blue-green phosphor 18 with phosphors of other colors, the LED light-emitting device 10 can be configured to emit a color other than white.
Further, green phosphor 19, yellow phosphor 20 and red phosphor 21 other than blue-green phosphor 18 of Embodiment 1 can be manufactured according to a known method.

As an example of the light emitting device of the present disclosure, an LD light emitting device including a phosphor of composition formula (2) and an LD element as a light source will be described with reference to FIG. FIG. 4 is a schematic diagram showing one embodiment of the LD light emitting device. As shown in FIG. 4 , the LD light emitting device 30 includes an LD element 31 , an incident optical system 32 and an LD wavelength conversion member 33 . LD wavelength conversion member 33 includes binder 34 and green phosphor 19 , yellow phosphor 20 , and red phosphor 21 in addition to blue-green phosphor 18 similar to that in FIG. 3 .

<LD element>
The LD element 31 can emit light with a higher optical power density than an LED. Therefore, by using the LD element 31, a high-output light emitting device can be constructed. The optical power density of the LD element 31 is, for example, 0.5 W/mm ² or more from the viewpoint of increasing the output of the LD light emitting device 30 . Also, the optical power density may be 2 W/mm ² or more, 3 W/mm ² or more, or 10 W/mm ² or more. On the other hand, if the optical power density is too high, the amount of heat generated from the phosphor irradiated with light increases, which may adversely affect the LD light emitting device 30 . Therefore, the optical power density may be 150 W/mm ² or less, 100 W/mm ² or less, 50 W/mm ² or less, or 20 W/mm ² or less. .

For the LD element 31, for example, one that emits light in the ultraviolet to blue region and has an emission spectrum peak at a wavelength of 400 nm or more and 450 nm or less is used. For example, an LD element that emits blue-violet light and an LD element that emits blue light can be used. In this embodiment, a case where the LD element 31 emits blue light will be described.

<LD wavelength conversion member>
The binder 34 in the LD wavelength conversion member 33 is, for example, a medium such as resin, glass, or transparent crystal. The binder 34 may be made of a single material, or may be made of different materials depending on the location.

The phosphor in the LD wavelength conversion member 33 wavelength-converts the emitted light from the LD element 31 into light with a longer wavelength. The phosphor of the LD wavelength conversion member 33 includes all of the green phosphor 19, the yellow phosphor 20, and the red phosphor 21 in addition to the blue-green phosphor 18 in this embodiment. At least one of the other phosphors may be mixed. As the blue-green phosphor 18, the phosphor of Embodiment 1 can be used. As the green phosphor 19, the yellow phosphor 20 and the red phosphor 21, those illustrated in FIG. 3 can be used. In FIG. 4, in particular, the case where the LD wavelength conversion member 33 is configured by mixing four kinds of green phosphor 19, yellow phosphor 20, and red phosphor 21 in addition to the blue-green phosphor 18 will be described. . The mixing ratio of the four types of phosphors can be appropriately adjusted according to the desired color tone of white light, the emission intensity of each phosphor, and the like.

Blue light emitted from the LD element 31 passes through an incident optical system 32 and is converted into blue light by the blue-green phosphor 18, green phosphor 19, yellow phosphor 20, and red phosphor 21 in the LD wavelength conversion member 33, respectively. It is converted into green light, green light, yellow light, and red light. The blue light that is emitted from the LD element 31 and is not absorbed by the four types of phosphors is mixed with the blue-green light, green light, yellow light, and red light to produce white light.
As described above, according to the light emitting devices of FIGS. 3 and 4, high color rendering properties and color reproducibility can be achieved because the phosphor of Embodiment 1 is used.

(Embodiment 2)
<Phosphor>
The phosphor according to Embodiment 2 is
The following compositional formula (3)
Lu _3-xz Er _x Ce _z Al _5-y Mg _y O ₁₂ (3)
including a material having a garnet-type crystal structure represented by
x, y, and z in formula (3) are the composition ratio of Er, the composition ratio of Mg, and the composition ratio of Ce, respectively;
x and y simultaneously satisfy 0.15≦x≦2.85, 0.25≦y≦1.25 and y≦0.56x+0.42, and z is in the range of 0<z≦0.12 .

In Embodiment 2 as well, the host crystal is a Lu ₃ Al ₅ O ₁₂ crystal having a garnet structure, and the Lu site 2 and Al site 3 in FIG. 1 are partly replaced to form a phosphor. That is, the Lu site 2 is replaced with Er and Ce, and the Al site 3 is replaced with Mg.
In the compositional formula (3), the value of z is greater than 0 because Ce must be included in order to obtain light emission. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. There is no particular limitation on the maximum value of z as long as the phosphor can emit light. However, when the value of z becomes too large, the emission intensity decreases due to concentration quenching. Therefore, by setting the value of z to 0.12 or less, it is possible to suppress the decrease in emission intensity. Also, the value of z is desirably 0.1 or less from the viewpoint of increasing the emission intensity.

<Manufacturing method of phosphor>
A method for manufacturing the phosphor material according to Embodiment 2 will be described below.
(1) First, raw material powder is prepared. Lutetium (Lu), erbium (Er), cerium (Ce), aluminum (Al), and magnesium (Mg) are prepared as raw materials, and lutetium oxide, erbium oxide, cerium oxide, aluminum oxide, and magnesium oxide are prepared as raw materials. . Materials other than these oxides can also be metal salt compounds such as carbonates.
(2) Next, weigh out predetermined amounts of these raw material powders and mix them thoroughly. The mixing method may be wet mixing in solution or dry mixing of dry powders. For mixing, industrially used ball mills, medium stirring mills, planetary mills, vibrating mills, jet mills, stirrers and the like can be used. Barium fluoride (BaF ₂ ) or strontium fluoride (SrF ₂ ) can be mixed as a flux corresponding to 0.1 wt % to 10 wt % of the mixed powder. Flux melts during firing and has the effect of promoting diffusion of each raw material and increasing reactivity.
(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for sintering. For example, the mixed powder is placed in an alumina crucible and heated together with the alumina crucible at 1200° C. or higher and 1700° C. or lower for 1 hour or more and 12 hours or less. After sintering, the powder is cooled, pulverized, and subjected to flux cleaning with an acid to obtain powder of the phosphor material.

<Evaluation of light emission characteristics>
The emission spectra of the phosphor material powders of Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-5 are measured using a spectrofluorophotometer using an integrating sphere. By setting the synthesized phosphor material powder at a predetermined position in the integrating sphere, irradiating the phosphor material powder with blue light emitted from a blue LED light source attached to the measuring device, and measuring the emission spectrum, Obtain the emission peak wavelength.

(criterion)
In the emission spectrum, those with an emission peak wavelength of 480 nm or more and less than 525 nm are evaluated as having excellent emission characteristics in the blue-green region, and those with an emission peak wavelength of 525 nm or more are evaluated as having insufficient emission characteristics in the blue-green region. x as a thing.

A list of the values of x, y, and z in the composition formula (3) and the emission peak wavelength of the phosphor material powders of Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-5 It is shown in Table 2 of FIG.

As shown in Table 2 of FIG. 8, by adjusting the composition ratio of Er and Mg, the emission peak wavelength of the phosphor material powders of Examples 2-1 to 2-13 was 480 nm or more and less than 525 nm. Therefore, the judgment is all 0. This is because by substituting Er at Lu site 2 and Mg at Al site 3, the influence as a crystal field that can be exerted on Ce, which is a light-emitting ion, was changed compared to the Lu ₃ Al ₅ O ₁₂ crystal without substitution. It is considered to be
The emission peak wavelengths of the powders of the phosphor materials of Comparative Examples 2-1 to 2-5 are 525 nm or more, and the judgment is x.

FIG. 5 is a diagram showing the relationship between the Er composition ratio and the Mg composition ratio at which the emission peak wavelength of the phosphor according to Embodiment 2 is 480 nm or more and less than 525 nm. The horizontal axis is the Er composition ratio, which corresponds to x in the composition formula (3). The vertical axis is the Mg composition ratio and corresponds to y in the composition formula (3). ◯ represents the portions where the emission peak wavelength is 480 nm or more and less than 525 nm in Examples 2-1 to 2-13. The X portion represents the portion where the emission peak wavelength is 525 nm or more in Comparative Examples 2-1 to 2-5. As shown in FIG. 5, in the relationship between the Er composition ratio and the Mg composition ratio, there is a boundary where the emission peak wavelength of the phosphor is 480 nm or more and less than 525 nm. Obtaining approximate straight lines along these boundaries reveals that x≧0.15, x≦2.85, y≧0.25, y≦1.25, and y≦0.56x+0.42. That is, if the Er composition ratio and the Mg composition ratio are within the solid line region surrounded by the approximate straight line in FIG. 5, the emission peak wavelength is 480 nm or more and less than 525 nm. That is, the compositional formula (3)
_{Lu3 -xzCezErxAl5- yMgyO12 ( 3 )}
x, y and z in formula (3) are the composition ratio of Er, the composition ratio of Mg, and the composition ratio of Ce, respectively, and x and y are x and y simultaneously satisfy 0.15 ≤ x ≤ 2.85, 0.25 ≤ y ≤ 1.25 and y ≤ 0.56x + 0.42, and z is in the range of 0 < z ≤ 0.12 For example, the emission peak wavelength is 480 nm or more and less than 525 nm.

Here, the values of z in Table 2 of FIG. 8 and FIG. 5 are all fixed at 0.09. Since Ce is an element that serves as an emission center, it has a large effect on the emission luminance, but has a small effect on the emission peak wavelength. Similar results are obtained.

<Light emitting device>
The light-emitting device according to Embodiment 3 has the same configuration as that of the light-emitting device according to Embodiment 1 shown in FIGS. However, the phosphor shown in the second embodiment is used for the blue-green phosphor 18 .

(Embodiment 3)
<Phosphor>
The phosphor of Embodiment 3 is
The following compositional formula (4)
_{Lu3 -xzErxCezAl5- ySiyO12 ( 4 )}
including a material having a garnet-type crystal structure represented by
x, y, and z in formula (4) are the composition ratio of Er, the composition ratio of Si, and the composition ratio of Ce, respectively;
x and y simultaneously satisfy 1.5≤x≤2.85 and 0.25≤y≤0.5, and z is in the range of 0<z≤0.12.

In Embodiment 3 as well, the host crystal is a Lu ₃ Al ₅ O ₁₂ crystal having a garnet structure, and the Lu site 2 and Al site 3 in FIG. 1 are partly replaced to form a phosphor. That is, the Lu site 2 is replaced with Er and Ce, and the Al site 3 is replaced with Si.
In the compositional formula (4), the value of z is greater than 0 because Ce must be included in order to obtain light emission. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. There is no particular limitation on the maximum value of z as long as the phosphor can emit light. However, when the value of z becomes too large, the emission intensity decreases due to concentration quenching. Therefore, by setting the value of z to 0.12 or less, it is possible to suppress the decrease in emission intensity. Also, the value of z is desirably 0.1 or less from the viewpoint of increasing the emission intensity.

<Manufacturing method of phosphor>
A method for manufacturing the phosphor material according to Embodiment 3 will be described below.
(1) First, raw material powder is prepared. Raw materials include lutetium (Lu), erbium (Er), cerium (Ce), aluminum (Al), and silicon (Si). Raw materials include lutetium oxide, erbium oxide, cerium oxide, aluminum oxide, and silicon oxide. . Materials other than these oxides can also be metal salt compounds such as carbonates.
(2) Next, weigh out predetermined amounts of these raw material powders and mix them thoroughly. The mixing method may be wet mixing in solution or dry mixing of dry powders. For mixing, industrially used ball mills, medium stirring mills, planetary mills, vibrating mills, jet mills, stirrers and the like can be used. Barium fluoride (BaF ₂ ) or strontium fluoride (SrF ₂ ) can be mixed as a flux corresponding to 0.1 wt % to 10 wt % of the mixed powder. Flux is effective in that it melts during firing, promotes diffusion of each raw material, and increases reactivity.
(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for sintering. For example, the mixed powder is placed in an alumina crucible and heated together with the alumina crucible at 1200° C. or higher and 1700° C. or lower for 1 hour or more and 12 hours or less. After sintering, the powder is cooled, pulverized, and subjected to flux cleaning with an acid to obtain powder of the phosphor material.

<Evaluation of light emission characteristics>
The emission spectra of the phosphor material powders of Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-5 are measured using a spectrofluorophotometer using an integrating sphere. By setting the synthesized phosphor material powder at a predetermined position in the integrating sphere, irradiating the phosphor material powder with blue light emitted from a blue LED light source attached to the measuring device, and measuring the emission spectrum, Obtain the emission peak wavelength.

(criterion)
In the emission spectrum, those with an emission peak wavelength of 480 nm or more and less than 525 nm are evaluated as having excellent emission characteristics in the blue-green region, and those with an emission peak wavelength of 525 nm or more are evaluated as having insufficient emission characteristics in the blue-green region. x as a thing.
A list of x, y, z values and emission peak wavelengths of composition formula (4) in the phosphor material powders of Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-5 It is shown in Table 3 of FIG.

As shown in Table 3 of FIG. 9, by adjusting the composition ratio of Er and Si, the emission peak wavelengths of the phosphor material powders of Examples 3-1 to 3-6 were 480 nm or more and less than 525 nm. Therefore, the judgment is all 0. This is because by substituting Er at Lu site 2 and Si at Al site 3, the effect of the crystal field that can be exerted on Ce, which is a light-emitting ion, has changed compared to the Lu ₃ Al ₅ O ₁₂ crystal without substitution. It is considered to be
The emission peak wavelength of the powders of the phosphor materials of Comparative Examples 3-1 to 3-5 is 525 nm or more, and the judgment is x.

FIG. 6 is a diagram showing the relationship between the Er composition ratio and the Si composition ratio at which the emission peak wavelength of the phosphor according to Embodiment 2 is 480 nm or more and less than 525 nm. The horizontal axis is the Er composition ratio, which corresponds to x in the composition formula (4). The vertical axis is the Si composition ratio and corresponds to y in the composition formula (4). ◯ represents the portions where the emission peak wavelength is 480 nm or more and less than 525 nm in Examples 3-1 to 3-6. The X portion represents the portion where the emission peak wavelength is 525 nm or more in Comparative Examples 3-1 to 3-5. As shown in FIG. 6, in the relationship between the Er composition ratio and the Si composition ratio, there is a boundary where the emission peak wavelength of the phosphor is 480 nm or more and less than 525 nm. Obtaining approximate straight lines along these boundaries reveals that x≧1.5, x≦2.85, y≧0.25, and y≦0.5, respectively. In other words, if the Er composition ratio and the Si composition ratio are within the solid line region surrounded by the approximate straight line in FIG. 6, the emission peak wavelength is 480 nm or more and less than 525 nm. That is, the compositional formula (4)
_{Lu3 -xzErxCezAl5- ySiyO12 ( 4 )}
x, y, and z in formula (4) are the composition ratio of Er, the composition ratio of Si, and the composition ratio of Ce, respectively, and x and y are When 1.5≦x≦2.85 and 0.25≦y≦0.5 are simultaneously satisfied, and z is in the range of 0<z≦0.12, the emission peak wavelength is 480 nm or more and less than 525 nm.

Here, the values of z in Table 3 of FIG. 9 and FIG. 6 are all fixed at 0.09. Since Ce is an element that serves as an emission center, it has a large effect on the emission luminance, but has a small effect on the emission peak wavelength. Similar results are obtained.

<Light emitting device>
The light-emitting device according to Embodiment 3 has the same configuration as that of the light-emitting device according to Embodiment 1 shown in FIGS. However, for the blue-green phosphor 18, the phosphor shown in the third embodiment is used.

It should be noted that the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and each embodiment and / or The effects of the embodiment can be obtained.

The phosphor according to the present invention has an emission peak wavelength in the range of 480 nm or more and less than 525 nm, emits a large amount of light in the blue-green region, and is capable of suppressing a decrease in light emission rate under irradiation with a high-output light source. Therefore, when applied to a light source that emits blue light, a light emitting device having excellent color rendering properties can be constructed, and can be suitably used as a light source for illumination or the like.

1 Garnet type crystal 2 Lu site 3 Al site 4 O site 10 LED light emitting device 11 LED element 12 Support 13 Solder 14 Bonding wire 15 Electrode 16 LED wavelength conversion member 17 LED encapsulant 18 Blue green phosphor 19 Green phosphor 20 Yellow Phosphor 21 Red Phosphor 30 LD Light Emitting Device 31 LD Element 32 Incident Optical System 33 LD Wavelength Conversion Member 34 Binder

Claims (5)

The following compositional formula (1)
_{Lu3 -xzCezErxAl5- yAyO12 ( 1 )}
including a material having a garnet-type crystal structure represented by
A is any one of Ga, Mg, and Si;
0<x≦2.85, 0.25≦y and
A phosphor, wherein 0<z≦0.12. The A is Ga,
0.15≦x≦2.85, 0.25≦y≦4.75 and y≧−3.75x+3.06
is
The phosphor according to claim 1. The A is Mg,
0.15≤x≤2.85, 0.25≤y≤1.25 and y≤0.56x+0.42
is
The phosphor according to claim 1. The A is Si,
1.5≤x≤2.85 and 0.25≤y≤0.5
is
The phosphor according to claim 1. The phosphor according to any one of claims 1 to 4;
a light source having an emission peak wavelength of 400 nm or more and 450 nm or less;
A light emitting device.

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