JP2021172669A - Phosphor and light emitting device including the same - Google Patents

Abstract

To provide a phosphor that prevents a decrease in emission brightness due to brightness saturation under a high-power light source and has excellent emission properties in a long wavelength region.SOLUTION: A phosphor comprises a material having garnet-type crystal structure represented by the following formula (1) Y3-x-zAxCezAl5-yLiyO12 (1). A is one of Yb, Eu, and La. In the formula (1), x, y and z represent a composition ratio of A, a composition ratio of Zn, and a composition ratio of Ce, respectively, and x, y, and z satisfy the relations of x≤2.7, 2.5≤y≤x+1.8 and 0<z≤0.15.SELECTED DRAWING: None

Description

The present invention relates to a phosphor that absorbs blue excitation light and emits red 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 in size, consuming less power, and capable of stably emitting high-intensity light, and instead of lighting fixtures such as incandescent lamps, Lighting fixtures using a light emitting device composed of an LED that emits white light are often 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 the composition formula of _{Y 3} Al ₅ O _{12: Ce is known.}

In the light emitting device having the above configuration, by applying a Ce-activated YAG phosphor to the element of the blue LED, white light is realized by mixing the blue light of the LED and the yellow light emitted from the Ce-activated YAG phosphor. .. However, in this configuration, the color is pale due to the emission characteristics of the Ce-activated YAG phosphor. Lighting for displays in stores, lighting for medical sites, etc. are required to have a slightly reddish warm white color, and are not suitable for emitting warm white light. Therefore, there is a demand for a red phosphor that absorbs blue light and fluoresces in red. This is the same requirement not only for LEDs but also for light sources using laser diodes (LDs) used in projectors and the like.

As a general red phosphor, for example, in Patent Document 1, in addition to the blue LED and the Ce-activated YAG-based phosphor, an Eu-activated nitride phosphor represented by the composition formula of _{Ca 2} Si ₅ N _{7: Eu is further added.} A light emitting device capable of emitting a warm reddish white color by combining them is disclosed.

Since the phosphor shown in Patent Document 1 has a peak wavelength of 600 nm or more, it exhibits a high color rendering index (Ra) at a color temperature in the light bulb color region of 3,250 K or less due to such a configuration, and is particularly red. It is possible to make a light emitting device that emits white light showing an excellent value in the special color rendering index (R9) indicating the appearance of.

Japanese Unexamined Patent Publication No. 2003-321675

However, the phosphor of Patent Document 1 has the following problems. For example, when a high-power excitation light source such as a blue LD is applied as an excitation light source to realize a high-luminance and high-color-developing light source, Eu with a short emission lifetime is activated as the emission center in the phosphor described in Patent Document 1. Therefore, under a high-power light source, the emission brightness cannot be increased due to the luminance saturation, and it is difficult to increase the output. Luminance saturation is a phenomenon in which the emission brightness from a phosphor is not proportional to the output of a light source, and it is known that the longer the emission lifetime of a emitting element, the more likely it is that brightness saturation will occur. In the case of the above-mentioned Ce-activated YAG-based phosphor, the emission lifetime of Ce is longer than that of Eu, so that brightness saturation is less likely to occur. Further, the matrix phase in which Eu of Patent Document 1 is activated is a nitride phosphor, and the management of the production process thereof, particularly the firing process for performing the synthesis reaction, is complicated and the cost tends to be high. For example, when Si ₃ N ₄ is used as a raw material, it is thermally decomposed at a high temperature, so that a furnace with a high pressure environment is required at the time of firing. In addition, during firing, it may be performed in an atmosphere such as ammonia, which may be a dangerous process. On the other hand, if it is an oxide phosphor, a high-pressure environment is not required, and it can be synthesized in the atmosphere depending on the material used. However, since the emission peak wavelength of a normal Ce-activated YAG phosphor exists in the vicinity of about 550 nm, it cannot be used as it is.

The present invention solves such a conventional problem, and it is possible to exhibit high color rendering properties with little decrease in emission brightness due to brightness saturation under a high output light source, and to have an emission peak wavelength of 600 nm or more and 700 nm or less. It is an object of the present invention to provide an oxide phosphor in which Ce is activated.

The phosphor according to the present disclosure is
The following composition formula (1)
Y _3-x-z A _x Ce _z Al _5-y Li _y O ₁₂ ... (1)
Including a material having a garnet-type crystal structure represented by
A is one of Yb, Eu, and La,
X, y, and z in the formula (1) are the composition ratio of A, the composition ratio of Li, and the composition ratio of Ce, respectively.
x and y satisfy x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8 at the same time.
z is characterized in that it is in the range of 0 <z ≦ 0.15.

Further, the light emitting device according to the present invention is
The above-mentioned phosphor and a light source having an emission peak wavelength of 400 nm or more and 500 nm or less.
It is characterized by having.

According to the phosphor according to the present invention, since its emission peak wavelength is 600 nm or more and 700 nm or less, it exhibits high color rendering properties in a long wavelength region in the visible light region. Further, since Ce is used, there is little decrease in emission brightness due to brightness saturation under irradiation with a high-power light source. Therefore, for example, in combination with a blue light source having a emission peak wavelength of 450 nm, a light emitting device having high brightness and high color rendering can be obtained. Further, since an oxide is used as the parent phase for activating Ce, it is possible to provide a phosphor having a reduced production cost without adopting a complicated process.

It is a schematic diagram of the crystal structure of the fluorescent substance mother crystal which concerns on Embodiment 1. FIG. It is a figure which shows the composition range which becomes the emission peak wavelength of 600 nm or more in Embodiment 1. FIG. It is a schematic diagram of the LED light emitting device which concerns on Embodiment 1. FIG. It is a schematic diagram of the LD light emitting device which concerns on Embodiment 1. FIG. It is a figure which shows the composition range which becomes the emission peak wavelength 600 nm or more in Embodiment 2. It is a figure which shows the composition range which becomes the emission peak wavelength 600 nm or more in Embodiment 3. Table 1 shows a list of x, y, and z values and emission peak wavelengths in the composition formulas (2) of Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-4. Table 2 shows a list of x, y, and z values and emission peak wavelengths of the composition formulas (3) of Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-4. Table 3 shows a list of x, y, and z values and emission peak wavelengths of the composition formulas (4) of Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-3.

The phosphor according to the first aspect has the following composition formula (1).
Y _3-x-z A _x Ce _z Al _5-y Li _y O ₁₂ ... (1)
Including a material having a garnet-type crystal structure represented by
A is one of Yb, Eu, and La,
X, y, and z in the formula (1) are the composition ratio of A, the composition ratio of Zn, and the composition ratio of Ce, respectively.
x, y, and z are x ≦ 2.7, 2.5 ≦ y ≦ x + 1.8, and
The range is 0 <z ≦ 0.15.

In the first aspect, the phosphor according to the second aspect is Yb.
The x and y may be 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8.

In the first aspect, the phosphor according to the third aspect is Eu.
The x and y may be 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8.

In the first aspect, the phosphor according to the fourth aspect is La.
The x and y may be x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8.

The light emitting device according to the fifth aspect includes the phosphor according to any one of the first to fourth aspects and the phosphor.
A light source having an emission peak wavelength of 400 nm or more and 500 nm or less,
It has.

Hereinafter, the phosphor and the light emitting device according to each embodiment of the present disclosure will be described with reference to the drawings. The components common to each figure are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

First, the features of the phosphor of the present invention common to each embodiment will be described.

The optical properties of the phosphor are determined by the type of mother crystal and emission center. _{For example, Y 3} Al ₅ O ₁₂ : Ce, which is generally known as a yellow phosphor, is a crystal having a garnet structure belonging to a cubic system as a mother crystal, and its emission center is Ce. FIG. 1 shows a schematic diagram of this garnet-type crystal 1. Among the sites constituting the garnet-type crystal 1, oxygen ions of O site 4 are coordinated to cations entering Y site 2 and Al site 3, and octahedral coordination and Al site 3 are coordinated at Y site 2. There are two types of coordination, octahedral coordination and tetrahedral coordination. Also in this embodiment, the mother crystal is a Y ₃ Al ₅ O ₁₂ type crystal having a garnet structure, a part of Y site 2 in FIG. 1 is replaced with Ce, and Y site 2 and Al site 3 are formed. It is a phosphor in which a part is replaced with another element. It should be noted that Ce, which is the center of light emission, is not shown because the amount added as a whole is very small and does not exist in all crystal lattices. By substituting a part of Y site 2 and Al site 3, the crystal field around Ce, which is the center of light emission, changes. Then, the 5d orbital of Ce is split, the band gap of Ce becomes smaller, and the emission wavelength shifts to the longer wavelength side.

The common elements in each of these embodiments can be represented by the following composition formula (1).
That is, the phosphor of the present disclosure is
Y _3-x-z A _x Ce _z Al _5-y Li _y O ₁₂ ... (1)
Contains a material having a garnet-type crystal structure represented by the composition formula (1) of
A is one of Yb, Eu, and La,
x ≦ 2.7, 2.5 ≦ y ≦ x + 1.8 and
It is characterized in that 0 <z ≦ 0.15.

In the above, x ≦ 2.7 is because the maximum possible composition ratio of Y site 2 as a garnet structure is 3, so when the composition ratio of A that replaces Y site 2 exceeds 2.7, This is because the crystals are considered to be unstable.
Further, y ≧ 2.5 means that when the composition ratio of Si substituting Al site 3 is less than 2.5, the influence of the crystal field on Ce, which is the luminescent element shown above, becomes small and the emission peak. This is because the influence on the wavelength is also small.
Further, 0 <z ≦ 0.15 means that Ce must be included in order to obtain light emission, so that the value of z is larger than 0. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. As long as the phosphor can emit light, the maximum value of z is not particularly limited. However, if the value of z becomes too large, the emission intensity is lowered due to the concentration quenching. Therefore, by setting the value of z to 0.15 or less, it is possible to suppress a decrease in emission intensity. The value of z is preferably 0.1 or less from the viewpoint of increasing the emission intensity.

(Embodiment 1)
<Fluorescent material>
The phosphor according to the first embodiment has the following composition formula (2).
Y _3-x-z Yb _x Ce _z Al _5-y Li _y O ₁₂ ... (2)
Including a material having a garnet-type crystal structure represented by
X, y, and z in the formula (2) are the composition ratio of Yb, the composition ratio of Li, and the composition ratio of Ce, respectively.
x and y simultaneously satisfy 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8.
z is in the range of 0 <z ≦ 0.15.

In the composition formula (2), since it is necessary to include Ce in order to obtain light emission, the value of z is larger than 0. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. As long as the phosphor can emit light, the maximum value of z is not particularly limited. However, if the value of z becomes too large, the emission intensity is lowered due to the concentration quenching. Therefore, by setting the value of z to 0.15 or less, it is possible to suppress a decrease in emission intensity. The value of z is preferably 0.1 or less from the viewpoint of increasing the emission intensity.

According to the phosphor according to the first embodiment, it has a garnet-type crystal structure represented by the above composition formula (2), and its emission peak wavelength is 600 nm or more and 700 nm or less, so that it has a length in the visible light region. Shows high color rendering properties in the wavelength range. Further, since Ce is used, there is little decrease in emission brightness due to brightness saturation under irradiation with a high-power light source.

<Manufacturing method of phosphor>
Hereinafter, a method for producing a fluorescent material according to the first embodiment will be described.
(1) As raw materials, yttrium (Y), ytterbium (Yb), cerium (Ce), aluminum (Al) and lithium (Li), as raw materials, yttrium oxide, ytterbium oxide, cerium oxide, aluminum oxide, and lithium oxide Prepare. The raw material is not limited to these oxides, but can be a metal salt compound such as a carbonate.
(2) Weigh a predetermined amount of the powder of the raw material and mix it sufficiently. The mixing method may be wet mixing in a solution or dry mixing of dry powder. Industrially used ball mills, medium stirring mills, planetary mills, vibration mills, jet mills, stirrers and the like can be used. _{Barium fluoride (BaF 2} ) and strontium fluoride (SrF ₂ ) can also be mixed as a flux equivalent to 0.1% by weight to 10% by weight of the mixed powder. The effect of the flux is that it melts during firing and is used to promote the diffusion of each raw material and enhance the reactivity.

(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for firing. For example, a mixed powder is placed in an alumina crucible and heated at 1200 ° C. or higher and 1700 ° C. or lower for 2 hours or more and 12 hours or less together with the alumina crucible.
(4) After firing, the fluorophore material powder can be obtained through steps such as cooling, crushing, and flux cleaning with an acid.
From the above, a fluorescent substance can be obtained.

<Evaluation of light emission characteristics>
The emission spectra of Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-4 are measured using a spectrofluorometer using an integrating sphere. The synthesized phosphor is placed at a predetermined position in the integrating sphere, the powder is irradiated with blue light emitted from a blue LED light source attached to the measuring device, and the emission spectrum is measured to obtain an emission peak wavelength.

(criterion)
In the emission spectrum, those having an emission peak wavelength of 600 nm or more and 700 nm or less are regarded as having excellent emission characteristics in the long wavelength region, and those having an emission peak wavelength of 620 nm or more and 700 nm or less are particularly excellent in emission characteristics. Those having an excellent emission peak wavelength of less than 600 nm are evaluated as ⊚, and those having an emission peak wavelength of less than 600 nm are evaluated as x as having insufficient emission characteristics in the long wavelength region.

Table 1 of FIG. 7 shows a list of x, y, z values and emission peak wavelengths of the composition formulas (2) of Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-4. show.

As shown in Table 1 of FIG. 7, by adjusting the composition ratio of Yb and Li, the emission peak wavelength of Examples 1-1 to 1-11 becomes 600 nm or more, and all the judgments are ⊚ or 〇. Become. This is because by substituting the Y site with Yb and the Al site with Li, the influence as a crystal field that can be given to the luminescent ion Ce has changed as compared with the _{Y 3} Al ₅ O _{12 crystal which is the mother crystal.} It is believed that there is.

The emission peak wavelength of Comparative Examples 1-1 to 1-4 is less than 600 nm, and the determination is x.

FIG. 2 is a diagram showing the relationship between the Yb composition ratio and the Li composition ratio at which the emission peak wavelength is 600 nm or more in the first embodiment. The horizontal axis is the Yb composition ratio, which corresponds to x in the composition formula (2). The vertical axis represents the Li composition ratio, which corresponds to y in the composition formula (2). The part ● represents a place where the emission peak wavelength in Examples 1-1 to 1-11 is 600 nm or more. Part X represents a portion where the emission peak wavelength in Comparative Examples 1-1 to 1-4 is less than 600 nm.

As shown in FIG. 2, there is a boundary in which the emission peak wavelength is 600 nm or more in the relationship between the Yb composition ratio x and the Li composition ratio y. When the approximate lines along this boundary are obtained, it can be seen that x ≦ 2.7, y ≧ 2.5, y ≦ x + 1.8, and x ≧ 1.2, respectively. That is, if the Yb composition ratio x and the Li composition ratio y exist inside the solid line portion surrounded by the approximate line in FIG. 2, the emission peak wavelength is 600 nm or more. That is, the composition formula (2)
Y _3-x-z Yb _x Ce _z Al _5-y Li _y O ₁₂ ... (2)
Including a material having a garnet-type crystal structure represented by, x, y and z in the formula (2) are the composition ratio of Yb, the composition ratio of Ce and the composition ratio of Li, respectively, and x and y are the composition ratios of Li. If 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8 are satisfied at the same time, and z is in the range of 0 <z ≦ 0.15, the emission peak wavelength is 600 nm or more.

Here, the values of z in Table 1 and FIG. 2 in FIG. 7 are all fixed at 0.09. Since Ce is an element that is the center of light emission, it has a large effect on the emission brightness, but it has a small effect on the emission peak wavelength. Therefore, if the range is 0 <z ≦ 0.15, z = 0.09 is not satisfied. The same result can be obtained.

<Light emitting device>
<LED light emitting device>
FIG. 3 is a schematic view of an example of the LED light emitting device 10 according to the first embodiment of the present disclosure. The LED light emitting device 10 including the phosphor 18 represented by the composition formula (2) and the LED chip 11 as a light source will be described below. FIG. 3 is a schematic schematic diagram showing an embodiment of the LED light emitting device 10. As shown in FIG. 3, the LED light emitting device 10 is fixed on the support 12 via solder 13 so that the LED chip 11 does not come into contact with the support 12. Further, the LED chip 11 is electrically connected to the electrode 15 arranged on the support 12 by the bonding wire 14. Further, the LED chip 11 is covered with an LED wavelength conversion member 16, and the LED wavelength conversion member 16 includes an LED encapsulant 17, a red phosphor 18, a yellow phosphor 19, and a green phosphor 20.

As the LED chip 11, for example, one that emits light in the ultraviolet to yellow region is used, and one having a peak in the emission spectrum at a wavelength of 400 nm or more and 500 nm or less is used. Specifically, as the LED chip 11, a blue LED chip or the like is used.

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

Silicone resin is used for the LED encapsulant 17 in the LED wavelength conversion member 16. The silicone resin may contain, for example, dimethyl silicone having high discoloration resistance. Further, methylphenyl silicone or the like having high heat resistance can also be used as the silicone resin. The silicone resin may be a homopolymer having a main skeleton with a siloxane bond defined by one kind of chemical formula. Further, it may be a copolymer containing a structural unit having a siloxane bond defined by two or more kinds of chemical formulas, or an alloy of two or more kinds of silicone polymers.

The phosphor in the LED wavelength conversion member 16 converts the light emitted from the LED chip 11 into light having a longer wavelength. The phosphor contained in the LED wavelength conversion member 16 is composed of a mixture of a red phosphor 18 and at least one of a yellow phosphor 19 or a green phosphor 20. As the red phosphor 18, the phosphor according to the first embodiment can be used. As the yellow phosphor 19, for example, Y ₃ Al ₅ O ₁₂ : Ce, α-SiAlON: Eu, or the like can be used. Further, as the green phosphor 20, Ca ₃ SiO _{4 Cl2} : Eu, β-SiAlON: Eu and the like can be used. In particular, FIG. 3 describes a case where the LED wavelength conversion member 16 is configured by mixing three types of the red phosphor 18, the yellow phosphor 19, and the green phosphor 20. The mixing ratio of the three 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. The three types of phosphors, the red phosphor 18, the yellow phosphor 19, and the green phosphor 20, are, for example, LED encapsulants at a ratio of 3 parts by weight or more and 70 parts by weight or less with respect to 100 parts by weight of the encapsulant. It is included in 17. If the content is less than 3 parts by weight, fluorescence having sufficient intensity cannot be obtained, so that it may not be possible to realize the LED light emitting device 10 that emits light having a desired wavelength. The weight ratio of the three 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 red phosphor 18 and a phosphor of another color, the LED light emitting device 10 can be configured as an LED light emitting device 10 that emits a color other than white.

The yellow phosphor 19 and the green phosphor 20 other than the red phosphor 18 according to the first embodiment can be produced according to a known method.

<LD light emitting device>
FIG. 4 is a schematic view of an example of the light emitting device 30 according to the first embodiment of the present disclosure. The LD light emitting device 30 including the phosphor 18 of the composition formula (2) and the LD element 31 as a light source will be described below. FIG. 4 is a schematic schematic diagram showing an embodiment of the LD light emitting device 30. 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. Further, the LD wavelength conversion member 33 includes a binder 34, a red phosphor 18, a yellow phosphor 19, and a green phosphor 20, which are the same as those in FIG.

The LD element 31 can emit light having a light power density higher than that of the LED. Therefore, a high output light emitting device can be configured by using the LD element 31. 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. Further, 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 light 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. ..

As the LD element 31, for example, one that emits light in the ultraviolet to yellow region is used, and one that has a peak in the emission spectrum at a wavelength of 400 nm or more and 500 nm or less is used. For example, an LD element that emits blue-purple light and an LD element that emits blue light can be used. In the first embodiment, a case where the LD element 31 emits blue light will be described.

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

The phosphor in the LD wavelength conversion member 33 converts the light emitted from the LD element 31 into light having a longer wavelength. The phosphor of the LD wavelength conversion member 33 is composed of a mixture of a red phosphor 18 and at least one of a yellow phosphor 19 or a green phosphor 20. As the red phosphor 18, the phosphor of the first embodiment is used. As the yellow phosphor 19 and the green phosphor 20, those exemplified in FIG. 3 can be used. In particular, FIG. 4 describes a case where the LD wavelength conversion member 33 is configured by mixing three types of the red phosphor 18, the yellow phosphor 19, and the green phosphor 20. The mixing ratio of the three 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.

The blue light emitted from the LD element 31 passes through the incident optical system 32, and is red light, yellow light, and green light by the red phosphor 18, the yellow phosphor 19, and the green phosphor 20 in the LD wavelength conversion member 33, respectively. Is converted to. The blue light emitted from the LD element 31 that was not absorbed by the above three types of phosphors, and the red light, yellow light, and green light converted by the red phosphor 18, the yellow phosphor 19, and the green phosphor 20, respectively. Is mixed to obtain white light.

As described above, according to the light emitting devices of FIGS. 3 and 4, since the phosphor according to the first embodiment is used, high color rendering property and color reproducibility can be realized when configured as a white light emitting device.

(Embodiment 2)
<Fluorescent material>
The phosphor according to the second embodiment has the following composition formula (3).
Y _3-x-z Eu _x Ce _z Al _5-y Li _y O ₁₂ ... (3)
Including a material having a garnet-type crystal structure represented by
X, y, and z in the formula (3) are the composition ratio of Eu, the composition ratio of Li, and the composition ratio of Ce, respectively.
x and y simultaneously satisfy 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8.
z is in the range of 0 <z ≦ 0.15.

Also in the second embodiment, the mother crystal is a Y ₃ Al ₅ O ₁₂ type crystal having a garnet structure, and is a phosphor in which a part of Y sites 2 and Al sites 3 in FIG. 1 is replaced. That is, the Y site is replaced by Eu and Ce, and the Al site is replaced by Li.

In the composition formula (3), since it is necessary to include Ce in order to obtain light emission, the value of z is larger than 0. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. As long as the phosphor can emit light, the maximum value of z is not particularly limited. However, if the value of z becomes too large, the emission intensity is lowered due to the concentration quenching. Therefore, by setting the value of z to 0.15 or less, it is possible to suppress a decrease in emission intensity. The value of z is preferably 0.1 or less from the viewpoint of increasing the emission intensity.

<Manufacturing method of phosphor>
Hereinafter, a method for producing a fluorescent material according to the second embodiment will be described.
(1) As raw materials, yttrium (Y), europium (Eu), cerium (Ce), aluminum (Al) and lithium (Li), as raw materials, yttrium oxide, europium oxide, cerium oxide, aluminum oxide, and lithium oxide. Prepare. The raw material is not limited to these oxides, but can be a metal salt compound such as a carbonate.
(2) Weigh a predetermined amount of the powder of the raw material and mix it sufficiently. The mixing method may be wet mixing in a solution or dry mixing of dry powder. Industrially used ball mills, medium stirring mills, planetary mills, vibration mills, jet mills, stirrers and the like can be used. _{Barium fluoride (BaF 2} ) and strontium fluoride (SrF ₂ ) can also be mixed as a flux equivalent to 0.1% by weight to 10% by weight of the mixed powder. The effect of the flux is that it melts during firing and is used to promote the diffusion of each raw material and enhance the reactivity.

(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for firing. For example, a mixed powder is placed in an alumina crucible and heated at 1200 ° C. or higher and 1700 ° C. or lower for 2 hours or more and 12 hours or less together with the alumina crucible.
(4) After firing, the fluorophore material powder can be obtained through steps such as cooling, crushing, and flux cleaning with an acid.
From the above, a fluorescent substance can be obtained.

<Evaluation of light emission characteristics>
The emission spectra of Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-4 are measured using a spectrofluorometer using an integrating sphere. The synthesized phosphor is placed at a predetermined position in the integrating sphere, the powder is irradiated with blue light emitted from a blue LED light source attached to the measuring device, and the emission spectrum is measured to obtain an emission peak wavelength.

(criterion)
In the emission spectrum, those having an emission peak wavelength of 600 nm or more and 700 nm or less are regarded as having excellent emission characteristics in the long wavelength region, and those having an emission peak wavelength of 620 nm or more and 700 nm or less are particularly excellent in emission characteristics. Those having an excellent emission peak wavelength of less than 600 nm are evaluated as ⊚, and those having an emission peak wavelength of less than 600 nm are evaluated as x as having insufficient emission characteristics in the long wavelength region.

Table 2 of FIG. 8 shows a list of x, y, z values and emission peak wavelengths of the composition formula (3) of Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-4. show.

As shown in Table 2 of FIG. 8, by adjusting the composition ratio of Eu and Li, the emission peak wavelength of Examples 2-1 to 2-11 becomes 600 nm or more, and all the judgments are ⊚ or 〇. Become. This is because by substituting the Y site with Eu and the Al site with Li, the influence as a crystal field that can be given to the luminescent ion Ce has changed as compared with the _{Y 3} Al ₅ O _{12 crystal which is the mother crystal.} It is believed that there is.

The emission peak wavelength of Comparative Examples 2-1 to 2-4 is less than 600 nm, and the determination is x.

FIG. 5 is a diagram showing the relationship between the Eu composition ratio and the Li composition ratio at which the emission peak wavelength is 600 nm or more in the second embodiment. The horizontal axis is the Eu composition ratio, which corresponds to x in the composition formula (3). The vertical axis represents the Li composition ratio, which corresponds to y in the composition formula (3). The part ● represents a place where the emission peak wavelength in Examples 2-1 to 2-11 is 600 nm or more. Part X represents a portion where the emission peak wavelength in Comparative Examples 2-1 to 2-4 is less than 600 nm.

As shown in FIG. 5, there is a boundary in which the emission peak wavelength is 600 nm or more in the relationship between the Eu composition ratio x and the Li composition ratio y. When the approximate lines along this boundary are obtained, it can be seen that x ≦ 2.7, y ≧ 2.5, y ≦ x + 1.8, and x ≧ 1.2, respectively. That is, if the Eu composition ratio x and the Li composition ratio y exist inside the solid line portion surrounded by the approximate line in FIG. 5, the emission peak wavelength is 600 nm or more. That is, the composition formula (3)
Y _3-x-z Eu _x Ce _z Al _5-y Li _y O ₁₂ ... (3)
Including a material having a garnet-type crystal structure represented by, x, y and z in the formula (3) are the composition ratio of Eu, the composition ratio of Ce and the composition ratio of Li, respectively, and x and y are If 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8 are satisfied at the same time, and z is in the range of 0 <z ≦ 0.15, the emission peak wavelength is 600 nm or more.

Here, the values of z in Table 2 and FIG. 5 in FIG. 8 are all fixed at 0.09. Since Ce is an element that is the center of light emission, it has a large effect on the emission brightness, but it has a small effect on the emission peak wavelength. Therefore, if the range is 0 <z ≦ 0.15, z = 0.09 is not satisfied. The same result can be obtained.

<Light emitting device>
Since the light emitting device according to the second embodiment has the same configuration as the light emitting devices 10 and 30 according to the first embodiment shown in FIGS. 3 and 4 except for the red phosphor, the description thereof will be omitted. However, as the red phosphor 18, the phosphor shown in the second embodiment is used.

(Embodiment 3)
<Fluorescent material>
The phosphor according to the third embodiment is
The following composition formula (4)
Y _3-x-z La _x Ce _z Al _5-y Li _y O ₁₂ ... (4)
Including a material having a garnet-type crystal structure represented by
X, y, and z in the formula (4) are the composition ratio of La, the composition ratio of Li, and the composition ratio of Ce, respectively.
x and y satisfy x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8 at the same time.
z is in the range of 0 <z ≦ 0.15.

Also in the third embodiment, the mother crystal is a Y ₃ Al ₅ O ₁₂ type crystal having a garnet structure, and is a phosphor in which a part of Y sites 2 and Al sites 3 in FIG. 1 is replaced. That is, the Y site is replaced with La and Ce, and the Al site is replaced with Li.

In the composition formula (4), since it is necessary to include Ce in order to obtain light emission, the value of z is larger than 0. The value of z is preferably 0.0001 or more, more preferably 0.003 or more, from the viewpoint of increasing the emission intensity. As long as the phosphor can emit light, the maximum value of z is not particularly limited. However, if the value of z becomes too large, the emission intensity is lowered due to the concentration quenching. Therefore, by setting the value of z to 0.15 or less, it is possible to suppress a decrease in emission intensity. The value of z is preferably 0.1 or less from the viewpoint of increasing the emission intensity.

<Manufacturing method of phosphor>
Hereinafter, a method for producing a fluorescent material according to the third embodiment will be described.
(1) As raw materials, yttrium (Y), lantern (La), cerium (Ce), aluminum (Al) and lithium (Li), as raw materials, yttrium oxide, lanthanum oxide, cerium oxide, aluminum oxide, and lithium oxide. Prepare. The raw material is not limited to these oxides, but can be a metal salt compound such as a carbonate.
(2) Weigh a predetermined amount of the powder of the raw material and mix it sufficiently. The mixing method may be wet mixing in a solution or dry mixing of dry powder. Industrially used ball mills, medium stirring mills, planetary mills, vibration mills, jet mills, stirrers and the like can be used. _{Barium fluoride (BaF 2} ) and strontium fluoride (SrF ₂ ) can also be mixed as a flux equivalent to 0.1% by weight to 10% by weight of the mixed powder. The effect of the flux is that it melts during firing and is used to promote the diffusion of each raw material and enhance the reactivity.

(3) Next, the mixed powder prepared as described above is fired. An electric furnace can be used for firing. For example, a mixed powder is placed in an alumina crucible and heated at 1200 ° C. or higher and 1700 ° C. or lower for 2 hours or more and 12 hours or less together with the alumina crucible.
(4) After firing, the fluorophore material powder can be obtained through steps such as cooling, crushing, and flux cleaning with an acid.
From the above, a fluorescent substance can be obtained.

<Evaluation of light emission characteristics>
The emission spectra of Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-3 are measured using a spectrofluorometer using an integrating sphere. The synthesized phosphor is placed at a predetermined position in the integrating sphere, the powder is irradiated with blue light emitted from a blue LED light source attached to the measuring device, and the emission spectrum is measured to obtain an emission peak wavelength.

(criterion)
In the emission spectrum, those having an emission peak wavelength of 600 nm or more and 700 nm or less are regarded as having excellent emission characteristics in the long wavelength region, and those having an emission peak wavelength of 620 nm or more and 700 nm or less are particularly excellent in emission characteristics. Those having an excellent emission peak wavelength of less than 600 nm are evaluated as ⊚, and those having an emission peak wavelength of less than 600 nm are evaluated as x as having insufficient emission characteristics in the long wavelength region.

Table 3 of FIG. 9 shows a list of x, y, z values and emission peak wavelengths of the composition formula (4) of Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-3. show.

As shown in Table 3 of FIG. 9, by adjusting the composition ratio of La and Li, the emission peak wavelength of Examples 3-1 to 3-11 becomes 600 nm or more, and all the judgments are ⊚ or 〇. Become. This is because by substituting the Y site with Eu and the Al site with Li, the influence as a crystal field that can be given to the luminescent ion Ce has changed as compared with the _{Y 3} Al ₅ O _{12 crystal which is the mother crystal.} It is believed that there is.

The emission peak wavelength of Comparative Examples 3-1 to 3-4 is less than 600 nm, and the determination is x.

FIG. 6 is a diagram showing the relationship between the La composition ratio and the Li composition ratio at which the emission peak wavelength is 600 nm or more in the second embodiment. The horizontal axis is the La composition ratio, which corresponds to x in the composition formula (4). The vertical axis represents the Li composition ratio, which corresponds to y in the composition formula (4). The part ● represents a place where the emission peak wavelength in Examples 3-1 to 3-12 is 600 nm or more. Part X represents a portion where the emission peak wavelength in Comparative Examples 3-1 to 3-3 is less than 600 nm.

As shown in FIG. 6, there is a boundary in which the emission peak wavelength is 600 nm or more in the relationship between the La composition ratio x and the Li composition ratio y. When the approximate lines along this boundary are obtained, it can be seen that x ≦ 2.7, y ≧ 2.5, and y ≦ x + 1.8, respectively. That is, if the La composition ratio x and the Li composition ratio y exist inside the solid line portion surrounded by the approximate line in FIG. 6, the emission peak wavelength is 600 nm or more. That is, the composition formula (4)
Y _3-x-z La _x Ce _z Al _5-y Li _y O ₁₂ ... (4)
Including a material having a garnet-type crystal structure represented by, x, y and z in the formula (4) are the composition ratio of La, the composition ratio of Ce and the composition ratio of Li, respectively, and x and y are If x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8 are satisfied at the same time and z is in the range of 0 <z ≦ 0.15, the emission peak wavelength is 600 nm or more.

Here, the values of z in Table 3 and FIG. 6 in FIG. 9 are all fixed at 0.09. Since Ce is an element that is the center of light emission, it has a large effect on the emission brightness, but it has a small effect on the emission peak wavelength. Therefore, if the range is 0 <z ≦ 0.15, z = 0.09 is not satisfied. The same result can be obtained.

<Light emitting device>
The light emitting device according to the third embodiment has the same configuration as the light emitting devices 10 and 30 according to the first embodiment shown in FIGS. 3 and 4 except for the red phosphor, and thus the description thereof will be omitted. However, as the red phosphor 18, the phosphor shown in the third embodiment is used.

It should be noted that the present disclosure includes appropriately combining any of the various embodiments and / or examples described above, and the respective embodiments and / or embodiments. The effects of the examples can be achieved.

The phosphor according to the present invention is a red phosphor having an emission peak wavelength in the range of 600 nm or more and 700 nm or less, having a large amount of emission in a long wavelength region, and capable of suppressing a decrease in emission rate under irradiation with a high-power light source. When this phosphor is applied to a light source that emits blue light, a light emitting device having excellent color rendering properties can be configured, and it can be suitably used as a light source for illumination or the like.

1 Garnet type crystal 2 Y site 3 Al site 4 O site 10 LED light emitting device 11 LED chip 12 Support 13 Solder 14 Bonding wire 15 Electrode 16 LED wavelength conversion member 17 LED encapsulant 18 Red phosphor 19 Yellow phosphor 20 Green Fluorescent material 30 LD light emitting device 31 LD element 32 Incident optical system 33 LD wavelength conversion member 34 Binder

Claims (5)

The following composition formula (1)
Y _3-x-z A _x Ce _z Al _5-y Li _y O ₁₂ ... (1)
Including a material having a garnet-type crystal structure represented by
A is one of Yb, Eu, and La,
X, y, and z in the formula (1) are the composition ratio of A, the composition ratio of Zn, and the composition ratio of Ce, respectively.
x, y, and z are x ≦ 2.7, 2.5 ≦ y ≦ x + 1.8, and
In the range of 0 <z ≦ 0.15,
Fluorescent material. The A is Yb,
The phosphor according to claim 1, wherein x and y are 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8. The A is Eu,
The phosphor according to claim 1, wherein x and y are 1.2 ≦ x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8. The A is La,
The phosphor according to claim 1, wherein x and y are x ≦ 2.7 and 2.5 ≦ y ≦ x + 1.8. The fluorescent substance according to any one of claims 1 to 4,
A light source having an emission peak wavelength of 400 nm or more and 500 nm or less,
Is equipped with a light emitting device.

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