JP7424530B2 - Light emitting device and phosphor - Google Patents

Description

The present invention relates to an infrared-emitting phosphor and a light-emitting device including a semiconductor light-emitting element and an infrared-emitting phosphor.

Infrared light emitting diodes made of GaAs-based compound semiconductors are known as light emitting devices that emit infrared light, and infrared light emitting diodes are widely used in areas such as sensors.
However, GaAs-based compound semiconductor light emitting diodes have problems such as poor temperature characteristics and low versatility. Furthermore, in infrared light emitting diodes made from GaAs-based compound semiconductors, subtle changes in manufacturing conditions cause fluctuations in the emission wavelength between products, and in order to obtain a predetermined emission wavelength, the yield of infrared light emitting diodes decreases. There was also the problem of high prices. Therefore, a better infrared light emitting device that can solve these problems has been desired. Therefore, attempts have been made to fabricate an infrared light-emitting device by combining a highly versatile GaN-based compound semiconductor light-emitting diode element and an infrared light-emitting phosphor.

Patent Document 1 is based on a GaN-based compound semiconductor blue light emitting diode element, a YAG:Ce,Er-based phosphor that absorbs blue light and emits yellow and infrared light, and a filter for blocking ultraviolet light or visible light. A light emitting device is disclosed.
Further, Patent Document 2 discloses an infrared light emitting LED using an infrared light emitting phosphor material on the light source. Specifically, it combines an infrared light-emitting phosphor material using yttrium gallium garnet (YGG) with Cr as a sensitizer and Nd, Yb, and Er as light-emitting ions, and an LED element that emits light at 660 nm. An example is shown.

On the other hand, Patent Document 3 describes an infrared luminescent material YAG:Fe, Er that has both magnetic properties and infrared luminescent properties as a luminescent compound used in a specific authentication system.

As another example of an infrared-emitting phosphor, Non-Patent Document 1 discloses that a phosphor using LaMgAl ₁₁ O ₁₉ as a host crystal and Cr ³⁺ activated emits light at 692 nm.
Non-Patent Document 2 discloses a fluorescent material that uses La ₃ GaGe ₅ O ₁₆ as a host crystal and activates Cr ³⁺ as a material that emits light at 700 nm.
Furthermore, as an example of another infrared-emitting phosphor, Non-Patent Document 3 describes that a phosphor using LaMgAl ₁₁ O ₁₉ as a host crystal and co-activating Cr ³⁺ and Nd ³⁺ emits light at 1060 nm and 1080 nm. Disclosed.
On the other hand, Non-Patent Document 4 discloses a fluorescent material that uses LaMgAl ₁₁ O ₁₉ as a host crystal and coactivates Tm ³⁺ and Dy ³⁺ as a material that emits visible light at 450 nm and 570 nm.
Furthermore, Non-Patent Document 5 discloses an infrared emitting material in which Cr ³⁺ and Tm ³⁺ are coactivated in germanium fluoride glass.

Japanese Patent Application Publication No. 2011-233586 Japanese Patent Application Publication No. 2012-531043 Special Publication No. 2013-508809

Materials Research Bulletin, 60: 397-400 (2014) Optical Materials Express, 6: 1247-1255 (2016) Materials Research Bulletin, 74: 9-14 (2016) J. Am. Ceram. Soc., 98(3): 788-794 (2015) AIP ADVANCES 4, 107145 (2014)

YAG:Ce,Er, which is an infrared-emitting phosphor disclosed in Patent Document 1, has an emission wavelength of around 1500 nm, so it receives light at a wavelength longer than the range that Si, which is the light-receiving element of the detector, can detect. There was also the problem that the detector could not detect it. Another problem with this phosphor is that it can only be excited with blue light. Furthermore, since a phosphor that strongly emits visible light is used, it is necessary to use means such as filters to create a light-emitting device that can only obtain infrared light, making the structure of the light-emitting device complicated. There was an issue.

The infrared emitting phosphor materials used in Patent Document 2 all emit light in a wavelength range of 1000 nm or more, and there was a problem in that they emitted light in a wavelength range in which the detection sensitivity of a Si detector was low. In addition, it only lists the types of transition metal elements and rare earth elements that are generally known in technical literature related to phosphors as sensitizers and luminescent ions, and which sensitizers and luminescent ions should be combined. It is completely unclear whether it is possible to obtain a phosphor with excitation and emission properties that meet the purpose.

The infrared light-emitting material described in Patent Document 3 has a problem in that the host lattice contains a very large amount of an element such as Fe, which also has magnetic properties, and the light-emitting properties are significantly deteriorated. Furthermore, since the emission of Er is around 1500 nm, as mentioned above, there is a problem that the wavelength is too long than the detection range of the detector and cannot be detected by the detector.

In the infrared emitting phosphors described in Non-Patent Documents 1 and 2, the emission wavelengths are 692 nm and 700 nm, so there was a problem that it was difficult to distinguish them from visible light. Conventionally known phosphors that use Cr ³⁺ as an activated ion are generally not affected by visible light emission, and there are no known ones that emit light in a wavelength range suitable for detection with a Si detector. First, it could not be said that it was a phosphor suitable for infrared light emitting devices.

In the infrared emitting phosphor described in Non-Patent Document 3, the emission wavelength is 1000 nm or more, so even if light is received at a wavelength longer than the range that Si, which is the light receiving element of the detector, can detect, it cannot be detected by the detector. There was a problem.

The luminescent material described in Non-Patent Document 4 has an emission wavelength of 450 nm and 570 nm, and is a luminescent material for white use that emits visible light upon ultraviolet excitation, so visible excitation cannot be performed in combination with a blue light emitting diode or the like. Furthermore, it cannot be used for infrared light emission.

In the infrared emitting material described in Non-Patent Document 5, the emission wavelength is 1500 nm or 1800 nm, so even if light is received at a wavelength longer than the range that Si, which is the light receiving element of the detector, can detect, it cannot be detected by the detector. There was a problem. Furthermore, since glass is used as the host, the behavior of activated ions within the crystal structure of a single crystal cannot be predicted. Therefore, when other single crystals are used as the host, the excitation characteristics and emission characteristics due to the combination of these activated ions cannot be predicted.

The present invention was made in view of these problems, and includes a novel infrared-emitting phosphor that emits light in a wavelength range where Si detectors are highly sensitive, and a semiconductor light-emitting material that emits light in an ultraviolet or visible wavelength range. An object of the present invention is to provide an infrared light emitting device including an element and the infrared light emitting phosphor.

As a result of intensive studies to solve the above problems, the present inventors have discovered that an infrared-emitting phosphor that emits infrared light in the wavelength range where Si detectors have high sensitivity, and that can be used as an ultraviolet, blue, green, or red semiconductor. The present invention was achieved by discovering an infrared-emitting phosphor that is also excited by light emitted from a light-emitting element, and discovering that this can solve the above problems.
That is, the gist of the present invention resides in the following [1] to [22].
[1] A light-emitting device including a semiconductor light-emitting element that emits ultraviolet light or visible light, and a phosphor that absorbs the ultraviolet light or visible light emitted from the semiconductor light-emitting element and emits light in the infrared region. A light-emitting device characterized in that a phosphor that emits light in an infrared region has an emission peak wavelength in a wavelength range of 700 to 1000 nm, and a waveform half width of the emission peak is less than 60 nm.
[2] The light emitting device according to [1], wherein the phosphor that emits light in the infrared region contains at least Tm or Cr as an activating element.
[3] The phosphor that emits light in the infrared region contains at least Tm as an activating element, and further contains at least one element selected from the group consisting of rare earth metal elements and transition metal elements, [1 ] or the light emitting device according to [2].
[4] The light emitting device according to [3], wherein the at least one element selected from the group consisting of rare earth metal elements and transition metal elements is at least one element among Cr, Mn, Sm, and Cu.
[5] The light emitting device according to [4], wherein at least one element selected from the group consisting of rare earth metal elements and transition metal elements is Cr.
[6] The minimum reflectance (%) in the wavelength range of 350 to 700 nm of the phosphor emitting light in the infrared region is lower than the minimum reflectance (%) in the wavelength range of 700 to 800 nm, and The light emitting device according to any one of [1] to [5], wherein the difference is 20% or more.
[7] The light emitting device according to any one of [1] to [6], wherein the emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting element is between 300 and 700 nm.
[8] It is characterized by containing a crystalline phase having a chemical composition represented by the following formula (1-2), absorbing ultraviolet light or visible light, and having an emission peak wavelength between 750 and 950 nm. and phosphor.
(M1 _a-b M2 _b ) ₃ (M3 _c-d M4 _d ) ₅ O ₁₂ ...(1-2)
However, M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements, and M2 represents the aforementioned rare earth metal elements, of which Tm is essential. Indicates one or more rare earth metal elements (excluding Sc) different from M1 as a metal element, and M3 is B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and M4 represents one or more metal elements selected from Hf, M4 represents one or more metal elements selected from Cr and Mn, O represents oxygen, and 0<a<1, 0<b≦0. 5, 0<c<1, 0<d≦0.5.
[9] The phosphor according to [8], wherein the crystal phase has a garnet structure.
[10] Contains a crystal phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm. and phosphor.
(A1 _1-a A2 _a ) ₂ (A3 _1-b A4 _b ) ₂ O ₆ ...(2-1)
However, A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than Tm and alkaline earth metal elements other than Mg, and A2 represents the rare earth metal element, which essentially includes Tm or Nd. A3 represents one or more metal elements selected from Mg, Co, and Zn, and A4 represents Cr, Mn, with Cr or Mn as essential. , Ni, Fe, and Cu; and one or more metal elements selected from B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, and Hf. , two or more metal elements, O represents oxygen, and 0<a≦0.5, 0<b≦0.75.
[11] The phosphor according to [10], wherein the crystal phase has a double perovskite structure.
[12] The phosphor according to [10] or [11], wherein in the formula (2-1), A4 is two or more metal elements containing Mn and Ge.
[13] It is characterized by containing a crystal phase having a chemical composition represented by the following formula (3-1), absorbing ultraviolet light or visible light, and having an emission peak wavelength between 750 and 1000 nm. and phosphor.
(D1 _1-a-b D2 _a D3 _b ) (D4 _1-a D5 _11+ac D6 _c ) O ₁₉ ...(3-1)
However, D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc), and D2 represents one or more metal elements selected from Ca, Sr, and Ba. , D3 represents one or more rare earth metal elements different from D1 as a rare earth metal element (excluding Sc), which requires Tm, and D4 represents one or more elements selected from Mg and Zn. D5 represents one or more metal elements selected from Al, Ga, In, and Sc; D6 represents one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu. O represents oxygen, and 0≦a≦0.99, 0<b≦0.2, and 0<c≦2.2.
[14] The phosphor according to [13], wherein the crystalline phase is a crystalline phase having a magnetoplumbite structure.
[15] The phosphor according to [13] or [14], wherein in formula (3-1), D6 contains at least Cr.
[16] It is characterized by containing a crystal phase having a chemical composition represented by the following formula (4-1), absorbing ultraviolet light or visible light, and having an emission peak wavelength between 700 and 1000 nm. and phosphor.
E1 ₅ (E2 _1-a E3 _a ) ₄ O ₁₅ ...(4-1)
However, E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of Ca, Sr, and Ba, and E2 represents Al, Ga, In, Sc, Y, Ti, Zr, Si, Represents one or more metal elements selected from Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W, and E3 is one or more metal elements different from E2 selected from transition metal elements. , O represents oxygen, and 0<a<0.2.
[17] The phosphor according to [16], wherein the crystal phase has a hexagonal perovskite structure.
[18] The phosphor according to [16] or [17], wherein in the formula (4-1), E2 contains at least Al.
[19] The phosphor according to any one of [16] to [18], wherein in the formula (4-1), E3 contains at least Cr.
[20] Contains a crystal phase with divalent samarium (Sm) and trivalent thulium (Tm) as activating elements in the host crystal, absorbs ultraviolet light or visible light, and has wavelengths from 800 to 1000 nm. A phosphor having an emission peak wavelength between 1 and 2.
[21] The host crystal is one or more metal elements selected from the group consisting of alkali metal elements and alkaline earth metal elements, and one or more metals selected from B, Al, Ga, Si, Ge, and P. and one or more elements selected from O, F, Cl, and Br, the phosphor according to [20].
[22] The phosphor according to [20] or [21], wherein the host crystal contains a crystal phase having a chemical composition represented by the following formula (5-1).
G1 _1-a G2 _a G3 _b O ₅ ...(5-1)
However, G1 represents one or more metal elements selected from alkaline earth metal elements, G2 represents two or more metal elements selected from rare earth metal elements, including Sm and Tm as essential elements, and G3 represents one or more metal elements selected from rare earth metal elements. , B, Al, Ga, Si, Ge and P, O represents oxygen, 0<a<0.2, 1.5<b<2.5 It is.

According to the present invention, a novel infrared-emitting phosphor emits light in a wavelength range where the detection sensitivity of a Si detector is high, specifically, the emission peak wavelength in the infrared region is between 700 and 1000 nm. A novel infrared-emitting phosphor having a waveform half width of an emission peak of less than 60 nm, and an infrared-emitting device comprising the infrared-emitting phosphor and a semiconductor light-emitting element that emits light in the wavelength range of ultraviolet light or visible light. can be provided. Further, it is possible to provide a light emitting device that can obtain only desired infrared light emission without using a complicated configuration such as a filter.
The infrared-emitting phosphor is a phosphor that emits light at a desired infrared wavelength and emits very little light at other wavelengths, so it is a phosphor with high luminous efficiency. In addition, the emission wavelength of an infrared-emitting phosphor is determined by the type of activating element and does not change, so when the infrared-emitting phosphor is used in a light-emitting device, there is no wavelength fluctuation between light-emitting devices. , an infrared light emitting device that emits light at a predetermined emission wavelength can be provided at low cost.

The emission spectra of the phosphors of Example 1-1 and Comparative Example 1-1 are shown. The excitation spectra of the phosphors of Example 1-1 and Comparative Example 1-1 are shown. The XRD pattern of the phosphor of Example 1-1 is shown. The emission spectrum of Example 1-2 is shown. The emission spectra of the phosphors of Example 2-1 and Comparative Example 2-1 are shown. The excitation spectra of the phosphors of Example 2-1 and Comparative Example 2-1 are shown. The XRD pattern of the phosphor of Example 2-1 is shown. The emission spectrum of the phosphor of Example 2-2 is shown. The excitation spectrum of the phosphor of Example 2-2 is shown. The XRD pattern of the phosphor of Example 2-2 is shown. The emission spectrum of the light emitting device of Example 2-3 is shown. The emission spectrum of the light emitting device of Example 2-4 is shown. The emission spectrum of the phosphor of Example 3-1 is shown. The excitation spectrum of the phosphor of Example 3-1 is shown. The XRD pattern of the phosphor of Example 3-1 is shown. The emission spectrum of the phosphor of Example 4-1 is shown. The excitation spectrum of the phosphor of Example 4-1 is shown. The XRD pattern of the phosphor of Example 4-1 is shown. The excitation spectrum (dotted line) and emission spectrum (solid line) of the phosphor of Example 5-1 are shown. The XRD pattern of the phosphor of Example 5-1 is shown.

Embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the content described below, and can be implemented with arbitrary changes within the scope of the gist thereof.
In addition, in this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as a lower limit value and an upper limit value. Furthermore, in the compositional formulas of phosphors in this specification, each compositional formula is separated by a comma (,). Furthermore, when a plurality of elements are listed separated by a comma (,), this indicates that one or more of the listed elements may be contained in any combination and composition.

{phosphor}
The phosphor according to the first embodiment of the present invention is an infrared phosphor that absorbs ultraviolet light or visible light emitted from a semiconductor light emitting device and emits light in the infrared region, and has an emission peak wavelength in the infrared region. It is characterized by a wavelength between 700 and 1000 nm. In this specification, the phosphor according to the first embodiment of the present invention may be referred to as an "infrared phosphor" or "infrared-emitting phosphor."
Here, the emission peak in the infrared region means the largest emission peak among the emission peaks in the wavelength range from 730 nm to 1000 nm. Therefore, the emission peak wavelength in the infrared region means the wavelength that produces the largest emission peak among the emission peaks in the wavelength range of 730 nm to 1000 nm.
Further, in this specification, ultraviolet light means light with a wavelength of less than 400 nm, and visible light means light with a wavelength of 400 nm to 700 nm.

[Emission spectrum]
The infrared phosphor according to the first embodiment preferably has the following characteristics when excited with light having a peak wavelength of 300 nm or more, 700 nm or less, or 650 nm or less and measuring the emission spectrum. Note that the peak wavelength refers to a wavelength that produces the largest emission peak among the emission peaks between wavelengths of 300 nm or more, 700 nm or less, or 650 nm or less.

The emission peak wavelength λp (nm) in the above-mentioned emission spectrum is usually 700 nm or more, preferably 730 nm or more, more preferably 750 nm or more, even more preferably 770 nm or more, still more preferably 780 nm or more, even more preferably 800 nm or more, and Usually 1000 nm or less, preferably 950 nm or less, more preferably 940 nm or less, even more preferably 930 nm or less, even more preferably 900 nm or less, even more preferably 880 nm or less, particularly preferably 870 nm or less, even more preferably 850 nm or less It is.
It is preferable that it is within the above range because it provides suitable infrared light emission.

Further, in the infrared phosphor according to the first embodiment, the half width of the waveform of the emission peak in the infrared region is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, even more preferably less than 60 nm. , even more preferably 50 nm or less, and more preferably 1 nm or more.
It is preferable that the half-width of the waveform of the light emission peak in the infrared region is within the above range because there is a tendency for high compatibility with the light receiving element that detects the infrared light emitted from the infrared phosphor. In addition, it is preferable because the emission intensity at a desired emission wavelength tends to be particularly high.

Note that in order to excite the above-mentioned infrared phosphor with light having a peak wavelength of 300 nm or more, 700 nm or less, or 650 nm or less, a xenon light source can be used, for example. Furthermore, the emission spectrum of the phosphor obtained in the first embodiment can be measured using, for example, a fluorescence spectrophotometer F-4500 or F-7000 (manufactured by Hitachi, Ltd.). The emission peak wavelength and the half-width of the waveform of the emission peak in the infrared region can be calculated from the obtained emission spectrum.
The half-width of the waveform of the luminescence peak in the infrared region may be determined by measuring the half-width of the waveform of the largest luminescence peak among the luminescence peaks in the wavelength range from 700 to 1000 nm. When observed overlapping with the maximum emission peak, the half-width is defined as the distance between the two wavelengths that are half the value of the largest emission peak. For example, in the emission spectrum of the phosphor of Example 1-1 in Figure 1-1, the peak having a peak top at 794 nm (the peak indicated by a black triangle) is the largest emission peak; The half-width was calculated by measuring the wavelength between 782.8 nm and 832.4 nm, which are the half-value (points indicated by black circles).

[Excitation spectrum]
The infrared phosphor according to the first embodiment usually has a wavelength of 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and usually 700 nm or less, preferably 650 nm or less, more preferably 600 nm or less, and even more preferably 550 nm or less. It has an excitation peak in the wavelength range of . That is, it is excited by light in the near ultraviolet to red or deep red region.

[Quantum efficiency/absorption efficiency]
The external quantum efficiency (η _o ) of the infrared phosphor according to the first embodiment is usually 3% or more, preferably 4% or more, more preferably 6% or more, still more preferably 25% or more, even more preferably It is 40% or more, even more preferably 50% or more. The higher the external quantum efficiency, the higher the luminous efficiency of the phosphor, which is preferable.
The internal quantum efficiency (η _i ) of the infrared phosphor according to the first embodiment is usually 5% or more, preferably 10% or more, more preferably 15% or more, still more preferably 20% or more, even more preferably It is 30% or more, even more preferably 50% or more, particularly preferably 70% or more, and even more preferably 90% or more. Internal quantum efficiency means the ratio of the number of photons emitted by an infrared phosphor to the number of photons of excitation light absorbed. Therefore, the higher the internal quantum efficiency, the higher the luminous efficiency and luminous intensity of the infrared phosphor, which is preferable.

The absorption efficiency of the infrared phosphor according to the first embodiment is usually 20% or more, preferably 25% or more, more preferably 30% or more, still more preferably 35% or more, and still more preferably 40% or more. It is even more preferably 50% or more, and particularly preferably 60% or more. The higher the absorption efficiency is, the higher the luminous efficiency of the phosphor is, and the less the amount of infrared phosphor used is, which is preferable.

[composition]
The composition of the infrared phosphor according to the first embodiment is not particularly limited as long as it has a desired emission peak wavelength. Note that the composition of the infrared phosphor can be confirmed by a generally known method. Examples include fluorescent X-ray analysis, high-frequency inductively coupled plasma (ICP) emission analysis, and X-ray photoelectron spectroscopy.
In order for the infrared phosphor according to the first embodiment to have an emission peak wavelength in the infrared region of 700 to 1000 nm, the infrared phosphor must contain an element selected from rare earth metal elements and transition metal elements as an activating element. More preferably, at least two elements selected from rare earth metal elements and transition metal elements are included. This is because when an infrared phosphor emits light using ultraviolet or visible light emitted from a semiconductor light emitting device as excitation light, it is difficult to increase the wavelength to a desired emission wavelength using only one type of activating element. It depends. Therefore, as the activating element, it is preferable to use a combination of an element that functions as a sensitizer and an element that functions as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light. Moreover, it is preferable that at least one element among Tm, Cr, and Sm is included as an activating element.
In addition, it is easy to obtain a phosphor with particularly high emission intensity at a desired emission wavelength by narrowing the half-width of the emission peak waveform, especially in the infrared region. It is preferable to appropriately combine the elements. Thereby, an infrared phosphor with high luminous efficiency can be obtained without losing excitation energy from the semiconductor light emitting device. Examples of elements that act as sensitizers include Ce, Eu, Cr, Mn, Cu, and Sm. Furthermore, examples of elements that act as light-emitting ions include Tm, Nd, Cr, and Sm. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is preferable that the activation element contains at least thulium (Tm) and further contains at least one element selected from rare earth metal elements and transition metal elements. . This is because Tm is preferable as an element that acts as a light-emitting ion.

Further, it is preferable that the activating element other than Tm is at least one element among Cr, Mn, Sm, and Cu. These elements absorb light ranging from ultraviolet light to visible light, and are particularly preferable as sensitizers for Tm to function as a light-emitting ion, and in combination with Tm, energy transfer is possible with high efficiency. Among these, the most preferred combination of activating elements is Tm and Cr.

[Crystal structure]
If an appropriate element is selected based on the above description, the infrared phosphor according to the first embodiment can be used regardless of the type/composition of the elements and crystal structure of the lattice crystal that constitutes the crystal phase of the infrared phosphor. First, it can be adjusted to have a desired emission peak wavelength.
The infrared phosphor according to the first embodiment can have various crystal structures as a crystal phase, such as a perovskite structure, a double perovskite structure, a hexagonal perovskite structure, a garnet structure, and a magnetoplumbite structure. Examples include structure.

[Reflectance]
From the viewpoint of wavelength conversion efficiency, the minimum reflectance (%) in the wavelength range of 350 to 700 nm of the phosphor that emits in the infrared region according to the first embodiment is the minimum reflectance (%) in the wavelength range of 700 to 800 nm. The difference between the two minimum reflectances is usually 20% or more, preferably 30% or more, and more preferably 50% or more. Moreover, it is usually smaller than 90%.

[Preferred embodiment 1-1]
The infrared phosphor according to the first embodiment contains a crystal phase having a chemical composition represented by the following formula (1-1), absorbs ultraviolet light or visible light, and has a wavelength of 750 to 950 nm. Examples include phosphors characterized by having an emission peak wavelength between 1 and 2. The crystalline phase is preferably a crystalline phase having a garnet structure.
(M1 _a-b M2 _b ) ₃ (M3 _c-d M4 _d ) ₅ O ₁₂ ...(1-1)
however,
M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 represents one or more rare earth metal elements (excluding Sc) different from M1 as the rare earth metal element,
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr, Mn, Fe, Ni, and Cu,
O represents oxygen;
0<a<1, 0<b≦0.5, 0<c<1, 0<d≦0.5.

M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding thulium (Tm) and scandium (Sc)) and alkaline earth metal elements.
Examples of rare earth metal elements include yttrium (Y) and lanthanum (La), but for reasons of low raw material cost, it is preferable that at least Y is included, and it is more preferable that 50 mol% or more of M1 is Y. , it is more preferable that 80 mol% or more of M1 is Y.
Examples of alkaline earth metal elements include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).
Note that M1 may be partially substituted with another element within a range that does not impair the effect as an infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

M2 represents one or more rare earth metal elements (excluding scandium (Sc)) that are different from M1 as the rare earth metal element. Such rare earth metal elements include cerium (Ce), europium (Eu), and thulium (Tm), and are not particularly limited as long as they are elements different from M1, but at least Tm is included because it emits infrared light. It is preferable that Tm accounts for 10 mol% or more of M2, and even more preferably that Tm accounts for 50 mol% or more of M2.

M3 is boron (B), aluminum (Al), gallium (Ga), indium (In), scandium (Sc), silicon (Si), germanium (Ge), titanium (Ti), tin (Sn), zirconium ( Zr) and hafnium (Hf). In order to easily activate the sensitizer, it is preferable that at least Al or Ga is included, more preferably 10 mol % or more of M3 is Al and/or Ga, and even more preferably Al or Ga.

M4 represents one or more metal elements selected from chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), and copper (Cu). Since it easily absorbs ultraviolet light and visible light, it preferably contains at least Cr or Mn, preferably 10 mol% or more of M4 is Cr and/or Mn, and more preferably Cr or Mn. Further, it is preferable that the content of a metal element having magnetic properties such as Fe is 50 mol % or less.

O represents oxygen, and may be partially substituted with another element within a range that does not impair the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), and nitrogen (N).

a represents the content of M1, and the range is usually 0<a<1, the lower limit is preferably 0.7 or more, more preferably 0.8 or more, and the upper limit is preferably 0. It is .999 or less, more preferably 0.990 or less.
b represents the content of M2, and its range is usually 0<b≦0.5, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably is 0.3 or less, more preferably 0.2 or less.
c indicates the content of M3, and the range is usually 0<c<1, the lower limit is preferably 0.7 or more, more preferably 0.8 or more, and the upper limit is preferably 0. It is .999 or less, more preferably 0.990 or less.
d indicates the content of M4, and its range is usually 0<d≦0.5, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably is 0.3 or less, more preferably 0.2 or less.

[Preferred embodiment 1-2]
Another preferred embodiment of the infrared phosphor according to the first embodiment is that it contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and absorbs wavelengths of Examples include phosphors characterized by having an emission peak wavelength between 750 and 950 nm. The crystalline phase is preferably a crystalline phase having a garnet structure.
(M1 _a-b M2 _b ) ₃ (M3 _c-d M4 _d ) ₅ O ₁₂ ...(1-2)
however,
M1 represents one or more metal elements selected from the group consisting of rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 represents one or more rare earth metal elements different from M1 as the rare earth metal element (excluding Sc), which requires Tm;
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr and Mn,
O represents oxygen;
0<a<1, 0<b≦0.5, 0<c<1, 0<d≦0.5.

In this embodiment, the explanation of the above "preferred embodiment 1-1" is used, except for the explanation of M2 and M4 below.
M2 represents one or more rare earth metal elements (excluding scandium (Sc)) that are different from M1 as the rare earth metal element, which essentially includes thulium (Tm).
Such rare earth metal elements include cerium (Ce) and europium (Eu), and are not particularly limited as long as they are elements different from M1, but Tm is essential because it emits infrared light, and 10 mol% of M2 More preferably, Tm accounts for 50 mol% or more of M2.
M4 represents one or more metal elements selected from chromium (Cr) and manganese (Mn). Since it easily absorbs ultraviolet light and visible light, it preferably contains at least Cr or Mn, preferably 10 mol% or more of M4 is Cr and/or Mn, and more preferably Cr or Mn. Further, it is preferable that the content of a metal element having magnetic properties such as iron (Fe) is 50 mol % or less.

[Preferred embodiment 1-3]
In the phosphor according to the preferred embodiment 1-2, M2 in the formula (1-2) is more preferably Tm. That is, it has a chemical composition represented by the following formula (1-3), contains a crystal phase having a garnet structure, absorbs ultraviolet light or visible light, and has an emission peak wavelength between 750 and 950 nm. It is a Tm ³⁺ activated infrared phosphor characterized by having the following properties.
(M1 _a-b M2 _b ) ₃ (M3 _c-d M4 _d ) ₅ O ₁₂ ...(1-3)
however,
M1 represents one or more metal elements selected from rare earth metal elements (excluding Tm and Sc) and alkaline earth metal elements,
M2 indicates Tm,
M3 represents one or more metal elements selected from B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and Hf,
M4 represents one or more metal elements selected from Cr and Mn,
O represents oxygen;
0<a<1, 0<b≦0.5, 0<c<1, 0<d≦0.5.

In this embodiment, the explanation of the above "preferred embodiment 1-1" is used, except for the explanation of M2 and M4 below.
M2 indicates Tm. By having Tm as an activating element, it is possible to obtain a high-quality infrared phosphor that has an emission peak in the wavelength range of 750 to 950 nm.
M4 represents one or more metal elements selected from chromium (Cr) and manganese (Mn). It is more preferable that 10 mol % or more of M4 is Cr, and even more preferable that it is Cr. Cr and Mn have strong absorption in ultraviolet light or visible light, and are particularly preferable as sensitizers for Tm to function as a light-emitting ion, and when combined with Tm, energy transfer is possible with high efficiency.

[Preferred embodiment 2-1]
Another preferred embodiment of the infrared phosphor according to the first embodiment is that it contains a crystalline phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and absorbs wavelengths of Examples include phosphors characterized by having an emission peak wavelength between 750 and 950 nm. Preferably, the crystal phase has a double perovskite structure.
(A1 _1-a A2 _a ) ₂ (A3 _1-b A4 _b ) ₂ O ₆ ...(2-1)
however,
A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than Tm and alkaline earth metal elements other than Mg,
A2 represents one or more metal elements different from A1 as the rare earth metal element, which essentially includes Tm or Nd;
A3 represents one or more metal elements selected from Mg, Co, and Zn,
A4 is one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu, with Cr or Mn being essential, and B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, and one or more metal elements selected from Hf,
O represents oxygen;
0<a≦0.5, 0<b≦0.75.

A1 represents one or more metal elements selected from the group consisting of rare earth metal elements other than thulium (Tm) and alkaline earth metal elements other than magnesium (Mg).
Examples of rare earth metal elements other than thulium (Tm) include scandium (Sc), yttrium (Y), and lanthanum (La), but for reasons of low raw material costs, it is preferable to include at least La, and 50% of A1 It is more preferable that mol % or more is La, it is even more preferable that 80 mol % or more of A1 is La, and it is particularly preferable that A1 is La.
Examples of alkaline earth metal elements other than Mg include calcium (Ca), strontium (Sr), and barium (Ba).
Note that A1 may be partially substituted with another element within a range that does not impair the effect as an infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

A2 represents one or more metal elements different from A1 as the rare earth metal element, which essentially includes at least thulium (Tm) or neodymium (Nd). By having Tm or Nd as an activating element, it is possible to obtain a high-quality infrared phosphor that has an emission peak in the wavelength range of 750 to 950 nm. Furthermore, when one or more metal elements different from A1 as the rare earth metal element, such as cerium (Ce) or europium (Eu), are included as an activating element, these act as a sensitizer and produce the desired effect. It is possible to intensify the light emission at certain wavelengths.

A3 represents one or more metal elements selected from magnesium (Mg), cobalt (Co), and zinc (Zn). Since it is not a heavy metal and has low toxicity, it preferably contains at least Mg or Zn, more preferably 10 mol% or more of A3 is Mg and/or Zn, even more preferably Mg or Zn, and Mg It is particularly preferable that there be.

A4 is one or more metal elements selected from chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe), and copper (Cu), which requires chromium (Cr) or manganese (Mn). and boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), titanium (Ti), tin (Sn), zirconium (Zr), and hafnium ( represents two or more metal elements, including one or more metal elements selected from Hf).

When A4 contains at least Cr or Mn as an activating element, it acts as a sensitizer and can increase the emission peak intensity in the wavelength range of 750 to 950 nm. Cr and Mn have strong absorption in ultraviolet light or visible light, and are particularly preferable as sensitizers for Tm to function as a light-emitting ion, and when combined with Tm, energy transfer is possible with high efficiency. A4 preferably contains Cr or Mn, and more preferably contains Mn. Further, the content of Cr and Mn in A4 is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, and 0.5 mol% or more in terms of the total amount of Cr and Mn. It is more preferable that

Furthermore, A4 contains one or more metal elements selected from B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, and Hf, thereby forming a host crystal that easily activates the sensitizer. Can be configured. Since it is easier to activate the sensitizer, A4 preferably contains Ge or Ti, and more preferably contains Ge. Further, the content of Ge and Ti in A4 is preferably 10 mol% or more, more preferably 50 mol% or more, and even more preferably 90 mol% or more, in terms of the total amount of Ge and Ti. .
Therefore, A4 is preferably two or more metal elements including Mn and Ge.

Ni, Fe, and Cu are also activating elements that act as sensitizers.
The molar ratio of the activation elements (Cr, Mn, Ni, Fe, Cu) and the metal elements (B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, Hf) constituting the host crystal in A4 is , preferably 0.1:99.9 to 50:50, more preferably 0.2:99.8 to 20:80, particularly preferably 0.5:99.5 to 10:90. .

O represents oxygen, and may be partially substituted with another element within a range that does not impair the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), and nitrogen (N).

a represents the content of A2, and the range is usually 0<a≦0.5, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably is 0.3 or less, more preferably 0.2 or less.
b indicates the content of A4, and the range is usually 0<b≦0.75, the lower limit is preferably 0.1 or more, more preferably 0.4 or more, and the upper limit is preferably is 0.7 or less, more preferably 0.6 or less.

[Preferred aspect 3-1]
Another preferred embodiment of the infrared phosphor according to the first embodiment is that it contains a crystalline phase having a chemical composition represented by the following formula (3-1), absorbs ultraviolet light or visible light, and absorbs wavelengths of Examples include phosphors characterized by having an emission peak wavelength between 750 and 1000 nm. The crystalline phase is preferably a crystalline phase having a magnetoplumbite structure.
(D1 _1-a-b D2 _a D3 _b ) (D4 _1-a D5 _11+ac D6 _c ) O ₁₉ ...(3-1)
however,
D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc),
D2 represents one or more metal elements selected from Ca, Sr, and Ba,
D3 indicates one or more rare earth metal elements different from D1 as a rare earth metal element (excluding Sc), which requires Tm;
D4 contains one or more metal elements selected from Mg and Zn,
D5 represents one or more metal elements selected from Al, Ga, In, and Sc,
D6 represents one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu,
O represents oxygen;
0≦a≦0.99, 0<b≦0.2, and 0<c≦2.2.

D1 represents one or more metal elements selected from rare earth metal elements (excluding Tm and Sc). Examples of rare earth metal elements other than thulium (Tm) and scandium (Sc) include yttrium (Y), gadolinium (Gd), lutetium (Lu), and lanthanum (La). It is preferable that D1 contains La, more preferably 50 mol% or more of D1 is La, even more preferably 80 mol% or more of D1 is La, and it is particularly preferable that D1 is La.
Note that D1 may be partially substituted with another element within a range that does not impair the effect as an infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

D2 represents one or more metal elements selected from calcium (Ca), strontium (Sr), and barium (Ba). Because it tends to form a single crystal phase, it is preferable that at least Ca or Sr is included, more preferably 10 mol% or more of D2 is Ca and/or Sr, and 50 mol% or more of D2 is Ca or Sr. More preferably, it is Sr.

D3 indicates one or more rare earth metal elements (excluding scandium (Sc)) that are different from D1 as a rare earth metal element, which essentially includes thulium (Tm). By having Tm as an activating element, it is possible to obtain a high-quality infrared phosphor having an emission peak in the wavelength range of 750 to 1000 nm. One or more rare earth metal elements (excluding Sc) different from D1 as a rare earth metal element include cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), and europium (Eu). ), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb), and the like. When such an element other than Tm is included as an activating element, these elements act as a sensitizer and can intensify light emission at a desired wavelength.

D4 represents one or more metal elements selected from magnesium (Mg) and zinc (Zn), more preferably 10 mol% or more of D4 is Mg, and more preferably 50 mol% or more of D4 is Mg. Preferably, D4 is particularly preferably Mg.

D5 represents one or more metal elements selected from aluminum (Al), gallium (Ga), indium (In), and scandium (Sc), and it is more preferable that 10 mol% or more of D5 is Al, It is more preferable that 50 mol% or more is Al, and it is particularly preferable that D5 is Al.

D6 represents one or more metal elements selected from chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe), and copper (Cu), and 10 mol% or more of D6 is Cr or Mn. More preferably, at least 20 mol% is Cr or Mn, particularly preferably at least 50 mol% is Cr or Mn.

O represents oxygen, and may be partially substituted with another element within a range that does not impair the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), and nitrogen (N).

a represents the content of D2, and its range is usually 0≦a≦0.99, the lower limit is preferably 0.01 or more, more preferably 0.1 or more, and the upper limit is preferably is 0.98
Below, it is more preferably 0.9 or less.
b indicates the content of D3, and the range is usually 0<b≦0.2, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably is 0.15 or less, more preferably 0.10 or less.
c indicates the content of D6, and the range is usually 0<c≦2.2, the lower limit is preferably 0.01 or more, more preferably 0.1 or more, and the upper limit is preferably is 2.0 or less, more preferably 1.5 or less.

[Preferred embodiment 4-1]
Another preferred embodiment of the infrared phosphor according to the first embodiment is that it contains a crystalline phase having a chemical composition represented by the following formula (4-1), absorbs ultraviolet light or visible light, and absorbs wavelengths of Examples include phosphors characterized by having an emission peak wavelength between 700 and 1000 nm. The crystal phase is preferably a crystal phase having a hexagonal perovskite structure.
E1 ₅ (E2 _1-a E3 _a ) ₄ O ₁₅ ...(4-1)
however,
E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of Ca, Sr, and Ba,
E2 represents one or more metal elements selected from Al, Ga, In, Sc, Y, Ti, Zr, Si, Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W,
E3 represents one or more metal elements different from E2 selected from transition metal elements,
O represents oxygen;
0<a<0.2.

E1 represents a rare earth metal element and one or more metal elements selected from the group consisting of calcium (Ca), strontium (Sr), and barium (Ba). Examples of rare earth metal elements include lanthanum (La), gadolinium (Gd), and lutetium (Lu). However, for reasons of low raw material cost, it is preferable to include at least La, and 40 mol% or more of E1 is La. More preferably, 60 mol% or more of E1 is La, and it is particularly preferable that E1 is La.
Note that E1 may be partially substituted with another element within a range that does not impair the effect as an infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

E2 is aluminum (Al), gallium (Ga), indium (In), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), silicon (Si), germanium (Ge), tin ( Sn), magnesium (Mg), zinc (Zn), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), and tungsten (W).
It is more preferable that 10 mol % or more of E2 is Al, even more preferably that 20 mol % or more of E2 is Al, and it is particularly preferable that 25 mol % or more of E2 is Al.
Further, it is more preferable that 10 mol % or more of E2 is Ti, it is still more preferable that 30 mol % or more of E2 is Ti, and it is particularly preferable that 50 mol % or more of E2 is Ti.
Moreover, it is preferable that 50 mol% or more of E2 is Al and Ti, it is more preferable that 70 mol% or more of E2 is Al and Ti, and it is still more preferable that 90 mol% or more of E2 is Al and Ti. preferable.
When the element that acts as an activating element is trivalent such as Cr ³⁺ , the activating element is introduced by replacing a part of Al, so the proportion of Al in E2 is larger than that of Ti. is preferred. However, the proportion occupied by Ti may be greater than that of Al for reasons such as ease of generation of crystal phases.
Note that, from the viewpoint of charge compensation, in the above preferable ratio, a part of Al may be replaced with Ga, In, Sc, or Y, and a part of Ti may be replaced with Zr, Si, Ge, or Sn.

E3 represents one or more metal elements different from E2 selected from transition metal elements. E3 acts as an activating element. Examples of E3 include chromium (Cr), manganese (Mn), and vanadium (V). It is more preferable that 10 mol % or more of E3 is Cr, it is preferable that 20 mol % or more of E3 is Cr, and it is particularly preferable that 50 mol % or more of E3 is Cr.

O represents oxygen, and may be partially substituted with another element within a range that does not impair the effect of the infrared phosphor according to this embodiment. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), and nitrogen (N).

a represents the content of E3, and the range is usually 0<a<0.2, the lower limit is preferably 0.001 or more, more preferably 0.005 or more, and the upper limit is preferably is 0.15 or less, more preferably 0.10 or less.

The phosphor according to this embodiment can emit infrared light in the above-mentioned range even when Cr ³⁺ , which did not show infrared light emission at a suitable wavelength in conventional phosphors, is used as an activated ion. It is excellent in that it has In the phosphor having the chemical composition expressed by the above formula (4-1), it is not clear how the emission wavelength of activated ions is adjusted, but it is possible that the E2 sites activated by Cr ³⁺ have different valences. This is thought to be related to the fact that Cr ³⁺ is shared by multiple metal cations, and the volume and symmetry of the polyhedron formed by the anions that coordinate to Cr 3+ .

[Preferred embodiment 5-1]
Another preferred embodiment of the infrared phosphor according to the first embodiment is that the host crystal contains a crystal phase having divalent samarium (Sm) and trivalent thulium (Tm) as activating elements, and Examples include phosphors that absorb light or visible light and have an emission peak wavelength between 750 and 1000 nm.

[Preferred embodiment 5-2]
In the phosphor according to the preferred embodiment 5-1, the host crystal contains one or more elements selected from the group consisting of alkali metal elements and alkaline earth metal elements, boron (B), aluminum (Al), gallium ( one or more metal elements selected from Ga), silicon (Si), germanium (Ge), and phosphorus (P), as well as oxygen (O), fluorine (F), chlorine (Cl), and bromine (Br) More preferably, it further contains one or more elements selected from.

[Preferred embodiment 5-3]
Further, in the phosphor according to the above preferred embodiment 5-1 or the phosphor according to the above preferred embodiment 5-2, the host crystal contains a crystal phase having a chemical composition represented by the following formula (5-1). More preferably, it is a phosphor that
G1 _1-a G2 _a G3 _b O ₅ ...(5-1)
however,
G1 represents one or more metal elements selected from alkaline earth metal elements,
G2 represents two or more metal elements selected from rare earth metal elements, including Sm and Tm as essential;
G3 represents two or more metal elements selected from B, Al, Ga, Si, Ge and P;
O represents oxygen;
0<a<0.2 and 1.5<b<2.5.

G1 represents one or more alkaline earth metal elements selected from Mg, Ca, Sr, and Ba, preferably 50 mol% or more of G1 is Sr and/or Ba, and 70 mol% or more is Sr. It is more preferable that Sr and/or Ba be used, and it is particularly preferable that 90 mol % or more be Sr and/or Ba. Incidentally, G1 may be partially substituted with another element within a range that does not impair the effect as an infrared phosphor according to this embodiment. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).
G2 represents two or more rare earth metal elements, including Sm and Tm as essential elements, and preferably 50 mol% or more of G2 is Sm and Tm, and 70 mol% or more is Sm and Tm. More preferably, 90 mol% or more is Sm and Tm.
G3 represents two or more metal elements selected from B, Al, Ga, Si, Ge, and P, preferably 50 mol% or more of G3 is B and P, and 70 mol% or more is B and P. It is more preferable that B and P account for 90 mol% or more.

<Light-emitting device>
A light emitting device according to a second embodiment of the present invention includes a semiconductor light emitting element that emits ultraviolet light or visible light, and a phosphor that absorbs the ultraviolet light or visible light emitted from the semiconductor light emitting element and emits light in the infrared region. The phosphor, which emits light in the infrared region, has an emission peak wavelength in the infrared region between 700 and 1000 nm, and a half-width of the waveform of the emission peak is less than 60 nm.

The light emitting device according to the second embodiment includes a semiconductor light emitting element, which will be described later, as a first light emitter (excitation light source), and a second light emitter that emits infrared light when irradiated with light from the first light emitter. Among the infrared phosphors according to the first embodiment described above, the emission peak wavelength in the infrared region of the phosphor that emits light in the infrared region is between 700 and 1000 nm, and the waveform of the emission peak is The present invention is a light emitting device including an infrared phosphor having a half width of less than 60 nm. As the infrared phosphor, any one type may be used alone, or two or more types may be used in combination in any combination and ratio.

[Composition of phosphor]
For specific aspects of the infrared phosphor according to this embodiment, the above-mentioned first embodiment is referred to.
In order for the infrared phosphor according to this embodiment to have an emission peak wavelength in the infrared region between 700 and 1000 nm and a half width of the waveform of the emission peak to be less than 60 nm, as an activating element, It is preferable that at least two or more elements selected from rare earth metal elements and transition metal elements are included. This is because when an infrared phosphor emits light using ultraviolet or visible light emitted from a semiconductor light emitting device as excitation light, it is difficult to increase the wavelength to a desired emission wavelength using only one type of activating element. It depends. Therefore, as the activating element, it is preferable to use a combination of an element that functions as a sensitizer and an element that functions as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light.

Among the activating elements, examples of elements that act as sensitizers include Ce, Eu, Cr, Mn, Cu, and Sm. Furthermore, examples of elements that act as light-emitting ions include Tm and Nd. By appropriately combining these materials, an infrared phosphor with high luminous efficiency can be obtained without losing excitation energy from the semiconductor light emitting device. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is preferable that the activation element contains at least thulium (Tm) and further contains at least one element selected from rare earth metal elements and transition metal elements. . This is because Tm is preferable as an element that acts as a light-emitting ion.

Further, it is preferable that the activating element other than Tm is at least one element among Cr, Mn, and Cu. These elements absorb light ranging from ultraviolet light to visible light, and are particularly preferable as sensitizers for Tm to function as a light-emitting ion, and in combination with Tm, energy transfer is possible with high efficiency. Among these, the most preferred combination of activating elements is Tm and Cr.

[Characteristics of phosphor]
The specific characteristics of the infrared phosphor according to this embodiment refer to the above-mentioned first embodiment.
In particular, from the perspective of wavelength conversion efficiency, the minimum reflectance (%) of a phosphor that emits in the infrared region in the wavelength range of 350 to 700 nm is the minimum reflectance (%) in the wavelength range of 700 to 800 nm. The difference between the two minimum reflectances is usually 20% or more, preferably 30% or more, and more preferably 50% or more. Moreover, it is usually smaller than 90%.

[Configuration of light emitting device]
The light-emitting device is not limited in its configuration, except that it has a first light-emitting body (excitation light source) and uses at least the infrared phosphor according to the present embodiment described above as a second light-emitting body. First, any known device configuration can be used.
Examples of the device configuration and embodiments of the light emitting device include those described in JP-A No. 2007-291352.
Other forms of the light emitting device include a bullet type, a cup type, a chip-on-board, a remote phosphor, and the like.

{Uses of light emitting devices}
The use of the light emitting device is not particularly limited, and it can be used in various fields where ordinary infrared light emitting devices are used. For example, a light source of an infrared monitoring device, a light source of an infrared sensor, an infrared light source of a medical diagnostic device, a light source of a transmitting element such as a photoelectric switch or a video game joystick, etc. can be used.

{Semiconductor light emitting device}
The semiconductor light emitting element included in the light emitting device according to this embodiment is not particularly limited as long as it emits ultraviolet light or visible light and functions as an excitation light source. Since it is commonly used as a semiconductor light emitting device and is cheap and easily available, the peak wavelength of ultraviolet or visible light emitted from the semiconductor light emitting device is between 300 and 700 nm. It is preferable. The wavelength is more preferably 300-650 nm or 350-680 nm, still more preferably 300-400 nm, 420-600 nm, 420-480 nm or 600-650 nm.

<Method for manufacturing phosphor>
The method for producing an infrared phosphor according to the first embodiment includes a step of mixing raw materials such as chlorides, fluorides, oxides, carbonates, and nitrates of each element, a step of firing, a step of crushing, It can include steps of washing and classifying.

[Phosphor raw material]
As the phosphor raw material used in the method for manufacturing the phosphor according to the first embodiment, known materials may be used as long as they do not impair the effects of the phosphor according to the first embodiment manufactured according to this embodiment. Can be done. For example, chlorides, fluorides, oxides, carbonates, nitrates, etc. of each element can be used, but are not limited to these.

[Mixing process]
The phosphor raw materials may be weighed to obtain the desired composition, thoroughly mixed using a ball mill, etc., then filled into a container, fired at a predetermined temperature in an atmosphere, and the fired product may be crushed and washed. For example, the chlorides, fluorides, oxides, carbonates, nitrates, etc. of each of the above elements may be weighed and mixed so that the molar ratio of each element matches the molar ratio in the desired composition formula.

The above-mentioned mixing method is not particularly limited, and may be either a dry mixing method or a wet mixing method.
Examples of the dry mixing method include a ball mill.
As a wet mixing method, for example, a solvent or dispersion medium is added to the above-mentioned phosphor raw material, mixed using a mortar and pestle to form a solution or slurry, and then spray-dried, heat-dried, or natural-dried. This is a drying method.
Examples of the solvent or dispersion medium include acetone, methanol, ethanol, 1-propanol, 1-butanol, and the like, with ethanol being preferred. The wet mixing time is usually 5 minutes or more, preferably 15 minutes or more, and more preferably 30 minutes or more. Further, the mixing may be repeated multiple times, usually once or more, preferably twice or more, and more preferably three times or more. In particular, it is preferable to mix for 15 minutes or more or to mix twice or more, since the phosphor according to the first embodiment of the present invention can be obtained as the main phase.

[Firing process]
The resulting mixture is filled into a container made of a material that has low reactivity with each phosphor raw material. The material of the container used during such firing is not particularly limited as long as it does not impair the effect of the phosphor according to the first embodiment manufactured by this embodiment, and examples thereof include containers made of alumina.
Although the firing temperature varies depending on other conditions such as pressure, firing can usually be carried out in a temperature range of 300°C or higher and 2000°C or lower. The maximum temperature reached in the firing step is usually 300°C or higher, preferably 1000°C or higher, more preferably 1300°C or higher, and usually 2000°C or lower, preferably 1700°C or lower. In particular, firing at a temperature range of 1400° C. or higher and 1600° C. or lower is preferable because the phosphor according to the first embodiment of the present invention can be obtained as the main phase in some cases.

If the firing temperature is too high, defects will be induced in the crystal structure due to atomic vacancies in the phosphor, and the luminescent properties will tend to deteriorate significantly. If the firing temperature is too low, the progress of the solid-state reaction will tend to be slow, and the target phase This may make it difficult for grain formation and grain growth to proceed.
The pressure during the firing process varies depending on the firing temperature, etc., but is usually 0.01 MPa or more, preferably 0.05 MPa or more, and usually 200 MPa or less, preferably 190 MPa or less.

The firing atmosphere in the firing step is arbitrary as long as the desired phosphor is obtained, but specific examples include an air atmosphere, a nitrogen atmosphere, a reducing atmosphere containing hydrogen or carbon, and among them, a reducing atmosphere is preferable. The number of times of firing is arbitrary as long as the desired phosphor is obtained, but after firing once, the obtained fired body may be crushed and then fired again, and there is no particular restriction on the number of times of firing. Furthermore, when firing multiple times, the atmosphere for each firing may be different.

The firing time varies depending on the temperature and pressure during firing, but is usually 1 minute or more, preferably 30 minutes or more, and usually 72 hours or less, preferably 12 hours or less. If the firing time is too short, the particles will not grow, making it impossible to obtain a phosphor with good properties. If the firing time is too long, the constituent elements will volatilize, causing defects in the crystal structure due to atomic vacancies. is induced, making it impossible to obtain a phosphor with good properties.

[Washing process]
There may be a step (cleaning step) of cleaning the phosphor obtained by firing before dispersing and classifying.
Impurities, mainly unreacted residues used in phosphor synthesis, and unreacted raw materials tend to remain in the phosphor, and side-reactants tend to form in the phosphor slurry. .
In order to improve the properties, it is necessary to remove unreacted residues and impurities generated during firing as much as possible. There are no particular restrictions on the cleaning method as long as impurities can be removed. For example, the generated phosphor can be washed with any liquid such as acids such as hydrochloric acid, hydrofluoric acid, nitric acid, acetic acid, and sulfuric acid, water-soluble organic solvents, alkaline solutions, and mixed solutions thereof. A reducing agent such as hydrogen peroxide may be included in the cleaning liquid, or the cleaning liquid may be heated or cooled within a range that does not significantly deteriorate the luminescent properties.

The time for immersing the phosphor in the cleaning solution varies depending on stirring conditions, etc., but is usually 10 minutes or more, preferably 1 hour or more, and usually 72 hours or less, preferably 48 hours or less. Further, washing may be performed multiple times, and the type and concentration of the washing liquid may be changed.
In the cleaning step, the phosphor can be manufactured by immersing and cleaning the phosphor, followed by filtration and drying. Further, cleaning using ethanol, acetone, methanol, etc. may be performed in between.

{Phosphor-containing composition}
The phosphor according to the first embodiment can also be used in combination with a liquid medium. In particular, when the phosphor according to the first embodiment is used in a light emitting device or the like, it is preferable to use the phosphor in a form dispersed in a liquid medium.

[Phosphor]
When the composition contains the phosphor according to the first embodiment, there is no restriction on the type of the phosphor, and it can be arbitrarily selected from the phosphors according to the first embodiment described above. Moreover, the number of the phosphors may be one, or two or more types may be used in combination in any combination and ratio. Furthermore, the composition may contain a phosphor other than the phosphor according to the first embodiment, as long as the effect of the phosphor according to the first embodiment is not significantly impaired.

[Liquid medium]
The liquid medium used in the composition is not particularly limited as long as it does not impair the performance of the phosphor according to the first embodiment within the intended range. For example, any inorganic and/or organic material can be used as long as it exhibits liquid properties under the desired usage conditions, can suitably disperse the phosphor according to the first embodiment, and does not cause undesirable reactions. Examples of such materials include silicone resins, epoxy resins, and polyimide silicone resins.

[Liquid medium and phosphor content]
The content of the phosphor according to the first embodiment and the liquid medium in the composition is arbitrary as long as it does not significantly impair the effect of the phosphor according to the first embodiment. The amount is usually 30% by weight or more, preferably 50% by weight or more, and usually 99% by weight or less, preferably 95% by weight or less, based on the entire product.

[Other ingredients]
Note that the composition may contain other components in addition to the phosphor and the liquid medium, as long as the effects of the phosphor according to the first embodiment are not significantly impaired. Moreover, only one type of other components may be used, or two or more types may be used in combination in any combination and ratio.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.
In addition, the values of various manufacturing conditions and evaluation results in the following examples are meant as preferred values of the upper or lower limits in each embodiment of the present invention, and the preferred ranges are the values of the upper or lower limits. It may be a range defined by a combination of and the values of the following examples or the values of the examples.

{Measuring method}
[Emission spectrum]
The emission spectrum was measured using a fluorescence spectrophotometer F-7000 (manufactured by Hitachi, Ltd.). More specifically, irradiation with excitation light of 455 nm at room temperature (25 ° C.) results in a wavelength of 500 nm or more and 900 nm or less (in the case of Comparative Example 1-1 and Example 1-1), or 750 nm or more and 850 nm or less (Comparative Example 2-1). 1. Emission spectra within the wavelength range of Example 3-1 to Example 3-3, Example 4-1, and Example 4-2) were obtained. Moreover, the emission peak wavelength was read from the obtained emission spectrum.

[Measurement of light emitting device]
In Examples 1-2, 2-3, and 2-4, the emission spectra of the infrared light emitting devices were measured using a compact fiber optic spectrometer USB2000 (manufactured by Ocean Optics). More specifically, the light emitting device was turned on and the emission spectrum of the light emitting device was obtained in a wavelength range of 300 nm or more and 900 nm or less.

[Excitation spectrum]
The excitation spectrum was measured using a fluorescence spectrophotometer F-7000 (manufactured by Hitachi, Ltd.). More specifically, the infrared emission peak is monitored at room temperature (25°C), and the infrared emission peak is 300 nm or more and 750 nm or less (in the case of Comparative Example 1-1 and Example 1-1), or 300 nm or more and 600 nm or less (Comparative Example 2- 1. Excitation spectra within the wavelength range of Example 3-1 to Example 3-3, Example 4-1, and Example 4-2) were obtained.

[Powder X-ray diffraction measurement]
Powder X-ray diffraction was precisely measured using a powder X-ray diffractometer D8 ADVANCE ECO (manufactured by BRUKER). The measurement conditions are as follows.

Using CuKα tube X-ray output = 40kV, 25mA
Diverging slit = automatic Detector = semiconductor array detector LYNXEYE, using Cu filter Scanning range 2θ = 5 to 90 degrees (for Comparative Example 1-1 and Example 1-1), or 5 to 90 degrees (for Comparative Example 2- 1. Cases of Example 3-1 to Example 3-3, Example 4-1, Example 4-2)
Reading width = 0.025 degrees

[Reflectance measurement]
In Example 1-1, Example 2-1, Example 3-1, and Example 4-1, the reflectance was measured using a spectrophotometer U-3310 (manufactured by Hitachi, Ltd.). More specifically, ₄ BaSO particles and the phosphor particles of the example were each placed in a quartz cell. Using BaSO ₄ particles as a reference sample, the reflectance (%) of the phosphor particles of the example was measured as a relative value to the reflectance of BaSO ₄ particles in a wavelength range of 300 nm or more and 900 nm or less.

(Comparative Example 1-1: Production of phosphor)
A YGG:Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was Y _2.97 Tm _0.03 Ga ₅ O ₁₂ .
Commercially available Y ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd. SY-OR-P-1622), G
A ₂ O ₃ powder (90402 manufactured by Mitsui Kinzoku Kogyo Co., Ltd.) and Tm ₂ O ₃ powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) were used. Each raw material was weighed so that the molar ratio of cations was Y:Ga:Tm=2.97:5.00:0.03. These raw materials are wet-mixed after adding ethanol in an alumina mortar, and the ethanol is air-dried before being placed in an alumina container.The container containing the mixed raw materials is placed in a small electric furnace (Super Burn, manufactured by Motoyama). A fired body was obtained by heating at 1500° C. for 8 hours in the atmosphere. A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.

The emission spectrum of the obtained phosphor is shown in FIG. 1-1, and the excitation spectrum is shown in FIG. 1-2 as thin lines. Note that the excitation light wavelength of the emission spectrum was 463 nm, and the emission wavelength of the excitation spectrum was 808 nm. From FIG. 1-1, it can be seen that the phosphor of this comparative example has an infrared emission peak around 800 nm.

(Example 1-1: Production of phosphor)
A YGG:Cr ³⁺ ,Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was Y _2.97 Tm _0.03 Ga _4.75 Cr _0.25 O ₁₂ .
Commercially available Y ₂ O ₃ powder (SY-OR-P-1622 manufactured by Shin-Etsu Chemical Co., Ltd.), Ga ₂ O ₃ powder (90402 manufactured by Mitsui Kinzoku Kogyo Co., Ltd.), and Cr ₂ O ₃ powder (B58840N manufactured by Kishida Chemical Co., Ltd.) were used as raw materials. , and Tm ₂ O ₃ powder (TM-04-001, manufactured by Shin-Etsu Chemical Co., Ltd.) were used. The procedure was the same as in Comparative Example 1-1, except that each raw material was weighed so that the molar ratio of cations was Y:Ga:Cr:Tm=2.97:4.75:0.25:0.03. The mixture was mixed and heated to obtain a phosphor.

The XRD pattern obtained by performing powder X-ray diffraction measurements on this phosphor is shown in Figure 1-3. It can be seen that the present phosphor is composed of single phase YGG. Furthermore, the emission spectrum of this phosphor is shown in FIG. 1-1, and the excitation spectrum is shown in FIG. 1-2, respectively, with thick lines. Note that the excitation light wavelength of the emission spectrum was 440 nm, and the emission wavelength of the excitation spectrum was 825 nm. From FIG. 1-1, it can be seen that the phosphor of this example has a strong infrared emission peak around 800 nm, the intensity of which is more than 6 times that of the phosphor of Comparative Example 1-1. Specifically, the wavelengths at which peaks are observed in the emission spectrum around 800 nm are 794 nm and 825 nm, and the waveforms of these peaks are observed to overlap, but the half-widths are 27.4 nm and 16.3 nm, respectively. Ta. The overlapping luminescence peaks were regarded as one luminescence peak, and the half width of the waveform of the luminescence peak was measured. As a result, the emission peak wavelength was 794 nm, and the half width of the waveform of the emission peak was 49.5 nm. Furthermore, from FIG. 1-2, it can be seen that the phosphor of this example is excited by light in a wide wavelength band from blue to red, and emits infrared light.
In addition, the minimum reflectance R1 (%) of this phosphor between wavelengths 350 and 700 nm and the minimum reflectance R2 (%) between wavelengths 700 and 800 nm were measured, and the difference R1-R2 (%) was calculated. The results are shown in Table 1.

(Example 1-2: Manufacturing of light emitting device)
An infrared light emitting device was fabricated by combining YGG:Cr ³⁺ , Tm ³⁺ and a blue LED.
The phosphor obtained in Example 1-1 and a thermosetting silicone resin were used as raw materials. Each raw material was weighed so that the weight ratio of phosphor to thermosetting silicone resin was 15:85. These raw materials were mixed using V-mini 300 manufactured by EME Co., Ltd., and applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko Co., Ltd.) and cured to obtain a light emitting device. The emission spectrum of the light emitting device is shown in Figure 1-4. It can be seen that the light emitting device has a peripheral infrared emission peak at approximately 800 nm.

(Comparative Example 2-1: Production of phosphor)
A La ₂ MgGeO ₆ :Tm ³⁺ phosphor was prepared by blending the raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgGeO ₆ .
As raw materials, commercially available La ₂ O ₃ powder (LA-04-153, manufactured by Shin-Etsu Chemical Co., Ltd.), MgO powder (LKG5947, manufactured by Wako Pure Chemical Industries, Ltd.), GeO ₂ powder (313826, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.), and Tm ₂ O ₃ Powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) was used. Each raw material was weighed so that the molar ratio of cations was La:Mg:Ge:Tm=1.98:1.00:1.00:0.02. These raw materials are wet-mixed after adding ethanol in an alumina mortar, and the ethanol is air-dried before being placed in an alumina container.The container containing the mixed raw materials is placed in a small electric furnace (Super Burn, manufactured by Motoyama). A fired body was obtained by heating at 1400° C. for 8 hours in the atmosphere. A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.

The emission spectrum of the obtained phosphor is shown in FIG. 2-1, and the excitation spectrum is shown in FIG. 2-2 as thin lines. Note that the excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 798 nm. From FIG. 2-1, it can be seen that the phosphor of this comparative example does not have an infrared emission peak around 800 nm.

(Example 2-1: Production of phosphor)
A La ₂ MgGeO ₆ :Mn ⁴⁺ ,Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgGe _0.99 Mn _0.01 O ₆ .
Commercially available La ₂ O ₃ powder (LA-04-153, manufactured by Shin-Etsu Chemical Co., Ltd.), MgO powder (LKG5947, manufactured by Wako Pure Chemical Industries, Ltd.), GeO ₂ powder (313826, manufactured by Kojundo Kagaku Kenkyusho), and Tm ₂ O ₃ powder as raw materials. (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) and MnO ₂ powder (194474 manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.) were used. Comparative Example 2 except that each raw material was weighed so that the molar ratio of cations was La:Mg:Ge:Tm:Mn=1.98:1.00:0.99:0.02:0.01. A phosphor was obtained by mixing and heating in the same manner as in -1.

The XRD pattern obtained by performing powder X-ray diffraction measurements on this phosphor is shown in Figure 2-3. It can be seen that the present phosphor consists of single phase La ₂ MgGeO ₆ .
Furthermore, the emission spectrum of this phosphor is shown in FIG. 2-1, and the excitation spectrum is shown in FIG. 2-2, respectively, with thick lines. Note that the excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 798 nm. From FIG. 2-1, it can be seen that the phosphor of this example has a strong infrared emission peak around 800 nm. The emission peak wavelength was 798 nm, and the half width of the waveform of the emission peak was 14.4 nm. Furthermore, from FIG. 2-2, it can be seen that the phosphor of this example is excited by light in a wide wavelength range from ultraviolet to blue, and emits infrared light.
In addition, the minimum reflectance R1 (%) of this phosphor between wavelengths 350 and 700 nm and the minimum reflectance R2 (%) between wavelengths 700 and 800 nm were measured, and the difference R1-R2 (%) was calculated. The results are shown in Table 1.

(Example 2-2: Production of phosphor)
A La ₂ MgTiO ₆ :Mn ⁴⁺ ,Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was La _1.98 Tm _0.02 MgTi _0.99 Mn _0.01 O ₆ .
As raw materials, commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Co., Ltd.), Mg (OH) ₂ powder (83480D manufactured by Kojundo Kagaku Kenkyusho), TiO ₂ powder (LAG1626 manufactured by Wako Pure Chemical Industries), Tm ₂ O ₃ powder (TM-04-001, manufactured by Shin-Etsu Chemical Co., Ltd.) and MnO ₂ powder (194474, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.) were used. Each raw material was weighed so that the molar ratio of cations was La:Mg:Ti:Tm:Mn=1.98:1.00:0.99:0.02:0.01. Other than that, mixing and heating were carried out in the same manner as in Example 2-1 to obtain a phosphor.
The XRD pattern obtained by performing powder X-ray diffraction measurements on this phosphor is shown in Figure 2-6. It can be seen that the present phosphor consists of single phase La ₂ MgTiO ₆ .
Furthermore, the emission spectrum of this phosphor is shown in FIG. 2-4, and the excitation spectrum is shown in bold line in FIG. 2-5. Note that the excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 804 nm. From FIG. 2-4, it can be seen that the phosphor of this example has a strong infrared emission peak around 800 nm. The emission peak wavelength was 804 nm, and the half width of the waveform of the emission peak was 26.2 nm. Furthermore, from FIGS. 2-5, it can be seen that the phosphor of this example is excited by light in a wide wavelength range from ultraviolet to blue, and emits infrared light.

(Example 2-3: Manufacturing of light emitting device)
An infrared light emitting device was fabricated by combining the phosphor La ₂ MgGeO ₆ :Mn ⁴⁺ , Tm ³⁺ obtained in Example 2-1 with a blue LED.
The phosphor obtained in Example 2-1 and a thermosetting silicone resin were used as raw materials. Each raw material was weighed so that the weight ratio of phosphor to thermosetting silicone resin was 15:85. These raw materials were mixed using V-mini 300 manufactured by EME Co., Ltd., and applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko Co., Ltd.) and cured to obtain a light emitting device. The emission spectrum of the light emitting device is shown in Figure 2-7. It can be seen that the light emitting device has an infrared emission peak around 800 nm.

(Example 2-4: Manufacturing of light emitting device)
An infrared light emitting device was fabricated by combining the phosphor La ₂ MgTiO ₆ :Mn ⁴⁺ , Tm ³⁺ obtained in Example 2-2 with a blue LED.
The phosphor obtained in Example 2-2 and a thermosetting silicone resin were used as raw materials. Other than that, weighing, coating, and curing were carried out in the same manner as in Example 2-3 to obtain a light-emitting device. The emission spectrum of the light emitting device is shown in Figure 2-8. It can be seen that the light emitting device has an infrared emission peak around 800 nm.

(Example 3-1: Production of phosphor)
A LaMgAl ₁₁ O ₁₉ :Cr ³⁺ ,Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was La _0.95 Tm _0.05 MgAl _10.67 Cr _0.33 O ₁₉ .
As raw materials, commercially available La(OH) ₃ powder (manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.), MgO powder (manufactured by Wako Pure Chemical Industries, Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), and Cr ₂ O ₃ powder (manufactured by Kishida) were used. (manufactured by Kagaku Co., Ltd.) and Tm ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd.) were used. Each raw material was weighed so that the molar ratio of cations was La:Tm:Mg:Al:Cr=0.95:0.05:1.00:10.67:0.33. After externally adding 5 wt% of H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) to these raw materials, ethanol was added in an alumina mortar and wet-mixed, and the ethanol was air-dried before being mixed in an alumina mortar. The container containing the mixed raw materials was placed in a small electric furnace (Super Burn, manufactured by Motoyama Co., Ltd.), and heated at 1500° C. for 8 hours in the atmosphere to obtain a fired body. A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.
In addition, the minimum reflectance R1 (%) of this phosphor between wavelengths 350 and 700 nm and the minimum reflectance R2 (%) between wavelengths 700 and 800 nm were measured, and the difference R1-R2 (%) was calculated. The results are shown in Table 1.

The emission spectrum of the obtained phosphor is shown by the solid line in FIG. 3-1, and the excitation spectrum is shown by the dotted line in FIG. 3-2. Note that the excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 809 nm.
From FIG. 3-1, it can be seen that the phosphor of this example has an infrared emission peak with a narrow half-width at 809 nm. Furthermore, from FIG. 3-2, it can be seen that the phosphor of this example is excited by light in a wide wavelength band from ultraviolet to blue, and emits infrared light. The half width of the waveform of the emission peak at the emission peak wavelength of 809 nm was 50 nm.
The XRD pattern obtained by powder X-ray diffraction measurement of the phosphor of this example is shown in FIG. 3-3. It can be seen that the phosphor of this example is made of LaMgAl ₁₁ O ₁₉ .

(Example 3-2: Production of phosphor)
Example 3-2 was performed in the same manner as Example 3-1 except that the raw materials were blended so that the phosphor obtained after synthesis was La _0.95 Tm _0.05 MgAl _10.89 Cr _0.11 O ₁₉ phosphor was obtained. According to the emission spectrum obtained when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, it was confirmed that the phosphor of this example had an infrared emission peak with a narrow half-width at 801 nm.

(Example 3-3: Production of phosphor)
Example 3-3 was performed in the same manner as Example 3-1 except that the raw materials were blended so that the phosphor obtained after synthesis was La _0.99 Tm _0.01 MgAl _10.67 Cr _0.33 O ₁₉ phosphor was obtained. According to the emission spectrum obtained when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, it was confirmed that the phosphor of this example had an infrared emission peak with a narrow half-width at 798 nm.

(Example 4-1: Production of phosphor)
A La ₅ AlTi ₃ O ₁₅ :Cr ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was La ₅ Al _0.99 Cr _0.01 Ti ₃ O ₁₅ .
As raw materials, commercially available La(OH) ₃ powder (manufactured by Kojundo Kagaku Kenkyujo Co., Ltd.), TiO ₂ powder (manufactured by Furuuchi Chemical Co., Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), and Cr ₂ O ₃ powder (manufactured by Kishida Chemical Co., Ltd.) were used. (manufactured by Seiko Co., Ltd.) was used. Each raw material was weighed so that the molar ratio of cations was La:Al:Cr:Ti=5:0.99:0.01:3. After externally adding 2 wt% of H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) to these raw materials, ethanol was added in an alumina mortar and wet-mixed, and the ethanol was air-dried before being mixed in an alumina mortar. The container containing the mixed raw materials was placed in a small electric furnace (Super Burn, manufactured by Motoyama Co., Ltd.), and heated at 1500° C. for 8 hours in the atmosphere to obtain a fired body. A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.

The emission spectrum of the obtained phosphor is shown by a solid line in FIG. 4-1, and the excitation spectrum is shown by a dotted line in FIG. 4-2. Note that the excitation light wavelength of the emission spectrum was 455 nm, and the emission wavelength of the excitation spectrum was 753 nm.
From FIG. 4-1, it can be seen that the phosphor of this example has an infrared emission peak with a narrow half-width at 753 nm. Furthermore, from FIG. 4-2, it can be seen that the phosphor of this example is excited by light in a wide wavelength range from ultraviolet to blue, and emits infrared light. The half width of the waveform of the emission peak at the emission peak wavelength of 753 nm was 41 nm.

The XRD pattern obtained by powder X-ray diffraction measurement of the phosphor of this example is shown in FIG. 4-3. It can be seen that the phosphor of this example mainly consists of La ₅ AlTi ₃ O ₁₅ . Note that the peak indicated by an arrow in FIG. 4-3 is LaAlO ₃ produced as a by-product as an impurity phase. The peak intensity in Figure 4-3 is small, and the emission of LaAlO ₃ :Cr usually has a maximum emission peak at about 737 nm and multiple weak emission peaks between 735 nm and 755 nm. Therefore, it can be said that the infrared emission peak with a narrow half-value width of 753 nm observed above is derived from La ₅ AlTi ₃ O ₁₅ .
In addition, the minimum reflectance R1 (%) of this phosphor between wavelengths 350 and 700 nm and the minimum reflectance R2 (%) between wavelengths 700 and 800 nm were measured, and the difference R1-R2 (%) was calculated. The results are shown in Table 1.

(Example 4-2: Production of phosphor)
A La ₅ AlTi ₃ O ₁₅ :Cr ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was La ₅ Al _0.95 Cr _0.05 Ti ₃ O ₁₅ .
As raw materials, commercially available La(OH) ₃ powder (manufactured by Kojundo Kagaku Kenkyujo Co., Ltd.), TiO ₂ powder (manufactured by Showa Denko), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), and Cr ₂ O ₃ powder (manufactured by Kishida Chemical Co., Ltd.) were used. (manufactured by) was used. Each raw material was weighed so that the molar ratio of cations was La:Al:Cr:Ti=5:0.95:0.05:3. After adding ethanol in an alumina mortar, wet mixing is carried out. After drying the ethanol naturally, it is placed in an alumina container, and the container containing the mixed raw materials is placed in a small electric furnace (Super Burn, manufactured by Motoyama). A fired body was obtained by heating at 1600° C. for 8 hours in the atmosphere. A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.
According to the emission spectrum obtained when the obtained phosphor was irradiated with excitation light having a wavelength of 455 nm, it was confirmed that the phosphor of this example had an infrared emission peak with a narrow half-width at 752 nm.

(Example 5-1: Production of phosphor)
A SrBPO ₅ :Sm ²⁺ ,Tm ³⁺ phosphor was produced by blending the raw materials so that the phosphor obtained after synthesis was Sr _0.96 Sm _0.03 Tm _0.01 BPO ₅ .
Commercially available SrHPO ₄ powder (manufactured by Hakushin Chemical Co., Ltd.), Sm ₂ O ₃ powder (manufactured by Mitsuwa Chemical Co., Ltd.), Tm ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd.) and H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) were used as raw materials. (manufactured by Kogyo Co., Ltd.) was used. Weigh each raw material so that the molar ratio of cations is Sr:Sm:Tm=0.96:0.03:0.01, mix it, put it in an alumina container, and put the mixed raw material in the container. A fired body was obtained by installing the product in a tubular furnace and heating it at 950° C. for 8 hours in a reducing atmosphere (N ₂ (96%) + H ₂ (4%)). A phosphor was obtained by crushing the fired body in an alumina mortar until there were no large lumps.
The emission spectrum when the obtained phosphor is irradiated with light with a wavelength of 455 nm is shown in a solid line in FIG. 5-1, and the excitation spectrum for an emission wavelength of 810 nm is shown in a dotted line. In FIG. 5-1, the half-width of the waveform of the emission peak in the wavelength range of 800 nm to 850 nm was 23 nm. As can be seen from FIG. 5-1, the phosphor of this example is excited over a wide wavelength range of 300 nm to 600 nm, and has an infrared emission peak with a narrow half-width between 800 nm and 850 nm.

Further, an XRD pattern obtained by powder X-ray diffraction measurement of the phosphor of this example is shown in FIG. 5-2. It can be seen that the phosphor of this example is made of _SrBPO5 .

Claims (9)

It is characterized by containing a crystal phase having a chemical composition represented by the following formula (3-1), absorbing ultraviolet light or visible light, and having an emission peak wavelength between 750 and 1000 nm, phosphor.
(D1 _1-a-b D2 _a D3 _b ) (D4 _1-a D5 _11+ac D6 _c ) O ₁₉ ...(3-1)
however,
D1 represents one or more rare earth metal elements selected from rare earth metal elements (excluding Tm and Sc),
D2 represents one or more metal elements selected from Ca, Sr, and Ba,
D3 indicates one or more rare earth metal elements different from D1 as a rare earth metal element (excluding Sc), which requires Tm;
D4 contains Mg,
D5 represents one or more metal elements selected from Al, Ga, In, and Sc, including at least Al;
D6 represents one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu, including at least Cr;
O represents oxygen;
0≦a≦0.99, 0<b≦0.2, and 0<c≦2.2. The phosphor according to claim 1, wherein the crystalline phase is a crystalline phase having a magnetoplumbite structure. a semiconductor light emitting device that emits ultraviolet light or visible light;
A light emitting device comprising a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light emitting element and emits light in the infrared region,
The phosphor that emits light in the infrared region includes the phosphor according to claim 1 or 2,
A light emitting device characterized in that the phosphor that emits light in the infrared region has an emission peak wavelength in the infrared region between 700 and 1000 nm, and a half width of the waveform of the emission peak is less than 60 nm. The light emitting device according to claim 3, wherein the phosphor that emits light in the infrared region contains at least Tm or Cr as an activating element. 4. The phosphor that emits light in the infrared region contains at least Tm as an activating element, and further contains at least one element selected from the group consisting of rare earth metal elements and transition metal elements. The light emitting device described in . The light emitting device according to claim 5, wherein the at least one element selected from the group consisting of rare earth metal elements and transition metal elements is at least one element among Cr, Mn, Sm, and Cu. The light emitting device according to claim 6, wherein at least one element selected from the group consisting of rare earth metal elements and transition metal elements is Cr. The minimum reflectance (%) in the wavelength range of 350 to 700 nm of the phosphor emitting light in the infrared region is lower than the minimum reflectance (%) in the wavelength range of 700 to 800 nm, and the difference is 20 nm. % or more, the light emitting device according to any one of claims 3 to 7. The light emitting device according to any one of claims 3 to 8, wherein the emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting element is between 300 and 700 nm.

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