JP7088027B2 - Luminescent 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 device and an infrared emitting phosphor.

As a light emitting device that emits infrared light, an infrared light emitting diode made of a GaAs-based compound semiconductor is known, and the infrared light emitting diode is widely used in the field of sensors and the like.
However, the GaAs-based compound semiconductor light emitting diode has problems such as poor temperature characteristics and low versatility. Further, in the infrared light emitting diode made of a GaAs-based compound semiconductor, the emission wavelength fluctuates between products due to a slight change in manufacturing conditions, and the yield of the infrared light emitting diode decreases in order to obtain a predetermined emission wavelength. There was also the problem that the price would be high. 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 emitting phosphor.

Patent Document 1 describes 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 preventing ultraviolet light or visible light from passing through. Is disclosed.
Further, Patent Document 2 discloses an infrared light emitting LED using an infrared light emitting phosphor material on a light source. Specifically, an infrared emitting fluorescent material using Cr as a sensitizer and Nd, Yb, and Er as luminescent ions in yttrium gallium garnet (YGG) is combined with an LED element that emits light at 660 nm. An example is shown.

On the other hand, Patent Document 3 describes an infrared light emitting material YAG: Fe, Er having both magnetic characteristics and infrared light emitting characteristics as a light emitting compound used in a specific authentication system.

Further, as an example of another infrared emitting fluorescent substance, Non-Patent Document 1 discloses that a fluorescent substance using LaMgAl ₁₁ O ₁₉ as a parent crystal and activating Cr ³⁺ emits light at 692 nm.
Non-Patent Document 2 discloses a fluorescent material in which La ₃ GaGe ₅ O ₁₆ is used as a parent crystal and activated with Cr ³⁺ as a material that emits light at 700 nm.
Further, as an example of another infrared emitting phosphor, Non-Patent Document 3 states that a phosphor having LaMgAl ₁₁ O ₁₉ as a parent crystal and co-activated with Cr ³⁺ and Nd ³⁺ emits light at 1060 nm and 1080 nm. It has been disclosed.
On the other hand, Non-Patent Document 4 discloses a fluorescent material containing LaMgAl ₁₁ O ₁₉ as a parent crystal and co-activated with Tm ³⁺ and Dy ³⁺ as a material exhibiting visible light emission at 450 nm and 570 nm.
Further, Non-Patent Document 5 discloses an infrared light emitting material in which Cr ³⁺ and Tm ³⁺ are co-activated with germanium fluoride glass.

Japanese Unexamined Patent Publication No. 2011-233586 Japanese Unexamined Patent Publication No. 2012-531043 Japanese Patent 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)

In YAG: Ce, Er, which is an infrared emission phosphor disclosed in Patent Document 1, since the emission wavelength is around 1500 nm, the light is received at a wavelength longer than the range that Si, which is the light receiving element of the detector, can detect. However, there was a problem that it could not be detected by the detector. In addition, there is a problem that this fluorescent substance can be excited only in blue. Furthermore, since a phosphor that strongly emits visible light is used, it is necessary to use a means such as a filter in order to manufacture a light emitting device that can obtain only infrared light, which complicates the structure of the light emitting device. There was a challenge.

All of the infrared emitting phosphor materials used in Patent Document 2 emit light in a wavelength region of 1000 nm or more, and have a problem that they emit light in a wavelength region where the detection sensitivity of the Si detector is low. In addition, only the types of transition metal elements and rare earth elements that are generally known in the technical literature related to phosphors as sensitizers and luminescent ions are listed, and which sensitizer and luminescent ion can be combined. It is completely unclear whether a phosphor having excitation and emission characteristics suitable for the purpose can be obtained.

The infrared light emitting material described in Patent Document 3 has a problem that the host lattice contains a very large amount of an element having magnetic properties such as Fe, and the light emitting properties are significantly deteriorated. Further, since the emission of Er is around 1500 nm, there is a problem that the wavelength is too long to be detected by the detector as described above.

The infrared emission phosphors described in Non-Patent Documents 1 and 2 have a problem that they are difficult to distinguish from visible light because the emission wavelengths are 692 nm and 700 nm. It is known that conventionally known phosphors using Cr ³⁺ as an active ion are usually not affected by visible light emission and emit light in a wavelength range suitable for detection by a Si detector. Therefore, it could not be said that the phosphor was suitable for the infrared light emitting device.

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

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

Since the infrared light emitting material described in Non-Patent Document 5 has a light emitting wavelength of 1500 nm and 1800 nm, the detector cannot detect the light even if the wavelength is longer than the range that Si, which is the light receiving element of the detector, can detect. There was a problem. Furthermore, since glass is used as the mother body, the behavior of activated ions in the crystal structure in a single crystal cannot be predicted. Therefore, the excitation characteristics and emission characteristics due to the combination of these activated ions cannot be predicted when another single crystal is used as the parent body.

The present invention has been made in view of such problems, and is a novel infrared emission phosphor that emits light in the wavelength range where the sensitivity of the Si detector is high, and semiconductor light emission that emits light in the wavelength range of ultraviolet light or visible light. 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 diligent studies to solve the above problems, the present inventors are infrared emitting phosphors that emit infrared light in a wavelength range where the sensitivity of the Si detector is high, and are any of ultraviolet, blue, green, and red semiconductors. We have discovered an infrared luminescent phosphor that is also excited by light emission from a light emitting element, and have found that this can solve the above-mentioned problems, and arrived at the present invention.
That is, the gist of the present invention lies 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 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 the emission peak wavelength in the infrared region of a phosphor that emits light in the region is between the wavelengths of 700 and 1000 nm, and the half-value width of the waveform 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 [2].
[4] The light emitting device according to [3], wherein at least one element selected from the group consisting of the rare earth metal element and the transition metal element 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 the rare earth metal element and the transition metal element is Cr.
[6] The minimum reflectance (%) of the phosphor that emits light in the infrared region between the wavelengths of 350 and 700 nm is lower than the minimum reflectance (%) between the wavelengths of 700 and 800 nm. 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 device is between wavelengths of 300 to 700 nm.
[8] It is characterized by containing a crystal 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 wavelengths of 750 and 950 nm. The phosphor.
(M1 _ab M2 _b ) ₃ (M3 _cd 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 rare earths requiring Tm. It represents one or more rare earth metal elements (excluding Sc) that are different from M1 as a metal element, where M3 is B, Al, Ga, In, Sc, Si, Ge, Ti, Sn, Zr, and. M4 indicates one or more metal elements selected from Hf, M4 indicates one or more metal elements selected from Cr and Mn, O indicates oxygen, and 0 <a <1, 0 <b ≦ 0. 5, 0 <c <1, 0 <d ≦ 0.5.
[9] The fluorescent substance according to [8], wherein the crystal phase is a crystal phase having a garnet structure.
[10] It is characterized by containing a crystal phase having a chemical composition represented by the following formula (2-1), absorbing ultraviolet light or visible light, and having an emission peak wavelength between wavelengths of 750 and 950 nm. The 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 is the rare earth metal element that requires Tm or Nd. Indicates one or more metal elements different from A1 as, A3 indicates one or more metal elements selected from Mg, Co, and Zn, and A4 indicates Cr or Mn, which requires Cr or Mn. , 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, 0 <a ≦ 0.5, 0 <b ≦ 0.75.
[11] The fluorescent substance according to [10], wherein the crystal phase is a crystal phase having a double perovskite structure.
[12] The fluorescent substance according to [10] or [11], wherein A4 is two or more metal elements containing Mn and Ge in the above formula (2-1).
[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 wavelengths of 750 and 1000 nm. The phosphor.
(D1 _1-a-b D2 _a D3 _b ) (D4 _1-a D5 _{11 + a-c} 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. Shown, D3 represents one or more rare earth metal elements (excluding Sc) different from D1 as a rare earth metal element that requires Tm, and D4 is one or more selected from Mg and Zn. D5 represents one or more metal elements selected from Al, Ga, In, and Sc, and D6 represents one or more metals selected from Cr, Mn, Ni, Fe, and Cu. An element is indicated, O indicates oxygen, and 0 ≦ a ≦ 0.99, 0 <b ≦ 0.2, 0 <c ≦ 2.2.
[14] The fluorescent substance according to [13], wherein the crystal phase is a crystal phase having a magnet plumbit structure.
[15] The fluorescent substance according to [13] or [14], wherein D6 contains at least Cr in the above formula (3-1).
[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 wavelengths of 700 and 1000 nm. The 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 is Al, Ga, In, Sc, Y, Ti, Zr, Si, Representing one or more metal elements selected from Ge, Sn, Mg, Zn, V, Nb, Ta, Mo, and W, 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 fluorescent substance according to [16], wherein the crystal phase is a crystal phase having a hexagonal perovskite structure.
[18] The fluorescent substance according to [16] or [17], wherein E2 contains at least Al in the above formula (4-1).
[19] The fluorescent substance according to any one of [16] to [18], wherein E3 contains at least Cr in the above formula (4-1).
[20] The matrix crystal contains a crystal phase having divalent sumalium (Sm) and trivalent turium (Tm) as active elements, absorbs ultraviolet light or visible light, and has a wavelength of 800 to 1000 nm. A phosphor characterized by having an emission peak wavelength in between.
[21] The parent 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. The phosphor according to [20], further comprising an element and one or more elements selected from O, F, Cl, and Br.
[22] The fluorescent substance according to [20] or [21], wherein the parent 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 indicates one or more metal elements selected from alkaline earth metal elements, G2 indicates two or more metal elements selected from rare earth metal elements that require Sm and Tm, and G3 indicates. , B, Al, Ga, Si, Ge and P represent two or more metallic elements, where O represents oxygen, 0 <a <0.2 and 1.5 <b <2.5. Is.

According to the present invention, a novel infrared emission fluorescent substance that emits light in a wavelength range in which the detection sensitivity of the Si detector is high, specifically, the emission peak wavelength in the infrared region is between the wavelengths of 700 and 1000 nm. An infrared light emitting device including a novel infrared light emitting phosphor having a half-value width of a waveform of a light emitting peak of less than 60 nm, a semiconductor light emitting element that emits light in the wavelength range of ultraviolet light or visible light, and the infrared light emitting phosphor. Can be provided. Further, it is possible to provide a light emitting device capable of obtaining only desired infrared light emission without adopting a complicated configuration such as a filter.
The infrared emitting phosphor is a fluorescent substance that emits light at a desired infrared wavelength and emits very little light at other wavelengths, and thus has high luminous efficiency. In addition, the emission wavelength of the infrared emitting phosphor is determined by the type of the activating element and does not change. Therefore, when the infrared emitting phosphor is used in the light emitting device, the wavelength does not fluctuate between the 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 fluorescent substance 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 fluorescent substance 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 fluorescent substance 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 fluorescent substance of Example 3-1 is shown. The emission spectrum of the phosphor of Example 4-1 is shown. The excitation spectrum of the fluorescent substance of Example 4-1 is shown. The XRD pattern of the fluorescent substance of Example 4-1 is shown. The excitation spectrum (dotted line) and the emission spectrum (solid line) of the phosphor of Example 5-1 are shown. The XRD pattern of the fluorescent substance of Example 5-1 is shown.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the contents described below, and can be arbitrarily modified and implemented without changing the gist thereof.
In addition, the numerical range represented by using "-" in this specification means the range including the numerical values before and after "-" as the lower limit value and the upper limit value. Further, in the composition formula of the fluorescent substance in the present specification, the delimiter of each composition formula is represented by a comma (,). Further, when a plurality of elements are listed separated by a comma (,), it is indicated that one or more of the listed elements may be contained in any combination and composition.

{Fluorescent body}
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 element and emits light in the infrared region, and has a emission peak wavelength in the infrared region. It is characterized by having a wavelength between 700 and 1000 nm. In the present specification, the phosphor according to the first embodiment of the present invention may be referred to as an "infrared phosphor" or an "infrared emitting phosphor".
Here, the emission peak in the infrared region means the largest emission peak among the emission peaks in the wavelength range of 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 between the wavelengths of 730 nm and 1000 nm.
Further, in the present specification, ultraviolet light means light having a wavelength of less than 400 nm, and visible light means light having 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 the emission spectrum is measured. The peak wavelength refers to a wavelength that produces the largest emission peak among emission peaks between a wavelength of 300 nm or more, 700 nm or less, or 650 nm or less.

The emission peak wavelength λp (nm) in the above emission spectrum is usually 700 nm or more, preferably 730 nm or more, more preferably 750 nm or more, more preferably 770 nm or more, still more preferably 780 nm or more, still more preferably 800 nm or more, and further. Usually 1000 nm or less, preferably 950 nm or less, more preferably 940 nm or less, still more preferably 930 nm or less, still more preferably 900 nm or less, still more preferably 880 nm or less, much more preferably 870 nm or less, still more preferably 850 nm or less. Is.
When it is within the above range, it is preferable in that it has suitable infrared 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, still more preferably less than 60 nm. Even more preferably, it is in the range of 50 nm or less, and more preferably 1 nm or more.
It is preferable that the half width of the waveform of the emission peak in the infrared region is within the above range because the consistency with the light receiving element for detecting the infrared emission emitted from the infrared phosphor tends to be high. In addition, it is preferable because the emission intensity at a desired emission wavelength tends to be particularly high.

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

[Excitation spectrum]
The infrared phosphor according to the first embodiment is usually 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, still more preferably 550 nm or less. Has an excitation peak in the wavelength range of. That is, it is excited by light in the red region or the deep red region from near-ultraviolet rays.

[Quantum efficiency / absorption efficiency]
The external quantum efficiency (η _o ) in 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, still more preferably. It is 40% or more, and 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 ) in 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, still more preferably. It is 30% or more, even more preferably 50% or more, remarkably preferably 70% or more, and even more preferably 90% or more. Internal quantum efficiency means the ratio of the number of emitted photons to the number of photons of the excitation light absorbed by the infrared phosphor. Therefore, the higher the internal quantum efficiency, the higher the luminous efficiency and the 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, still more preferably 40% or more, and more preferably 40% or more. It is even more preferably 50% or more, and much more preferably 60% or more. The higher the absorption efficiency, the higher the luminous efficiency of the phosphor and the smaller the amount of the infrared phosphor used, 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. The composition of the infrared phosphor can be confirmed by a generally known method. For example, fluorescent X-ray analysis, high frequency inductively coupled plasma (ICP) emission analysis, X-ray photoelectron spectroscopy analysis and the like can be mentioned.
The infrared phosphor according to the first embodiment contains an element selected from rare earth metal elements and transition metal elements as an activating element in order to make the emission peak wavelength in the infrared region from 700 to 1000 nm. It is preferable, and more preferably, it contains at least two or more elements selected from rare earth metal elements and transition metal elements. This is because when the infrared phosphor emits light using ultraviolet light or visible light emitted from a semiconductor light emitting element as excitation light, it is difficult to extend the wavelength to a desired emission wavelength with only one type of activating element. It depends. Therefore, as the activating element, it is preferable to use a combination of an element that acts as a sensitizer and an element that acts as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light. Further, it is preferable to contain at least one element of Tm, Cr, and Sm as the activating element.
Further, since it is easy to obtain a phosphor having a particularly high emission intensity at a desired emission wavelength by narrowing the half width of the emission peak waveform particularly in the infrared region, activation that works as the following sensitizer and emission ion. It is preferable to appropriately combine the elements. As a result, an infrared phosphor having high luminous efficiency can be obtained without losing the excitation energy from the semiconductor light emitting device. Examples of the element acting as a sensitizer include Ce, Eu, Cr, Mn, Cu, Sm and the like. Further, examples of the element acting as a luminescent ion include Tm, Nd, Cr, Sm and the like. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is more preferable to contain at least thulium (Tm) as an activating element and further contain 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 luminescent 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 are particularly preferable as a sensitizer for absorbing visible light from ultraviolet light and for Tm to act as luminescent ions, and when combined with Tm, energy transition is possible with high efficiency. Of these, the most preferable combination is that the activating element is Tm and Cr.

[Crystal structure]
The infrared phosphor according to the first embodiment can be selected regardless of the type / composition and crystal structure of the elements of the lattice crystal constituting the crystal phase of the infrared phosphor if an appropriate element is selected based on the above description. However, 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, and for example, a perovskite structure, a double perovskite structure, a hexagonal perovskite structure, a garnet structure, and a magnet planbite. The structure and the like can be mentioned.

[Reflectance]
From the viewpoint of wavelength conversion efficiency, the minimum reflectance (%) of the phosphor emitting in the infrared region according to the first embodiment between the wavelengths of 350 and 700 nm is the minimum between the wavelengths of 700 and 800 nm. It is lower than the reflectance (%), and the difference between the two minimum reflectances is usually 20% or more, preferably 30% or more, and more preferably 50% or more. Also, it is usually less than 90%.

[Preferable Aspect 1-1]
As the infrared phosphor according to the first embodiment, it 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 thereof include a phosphor characterized by having an emission peak wavelength between them. The crystal phase is preferably a crystal phase having a garnet structure.
(M1 _ab M2 _b ) ₃ (M3 _cd 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 indicates 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 the rare earth metal element include yttrium (Y) and lanthanum (La), but it is preferable to contain at least Y for the reason of cheap raw materials, and it is more preferable that 50 mol% or more of M1 is Y. , 80 mol% or more of M1 is more preferably Y.
Examples of the alkaline earth metal element include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).
In addition, M1 may be partially substituted with another element as long as the effect as an infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and the like.

M2 represents one or more rare earth metal elements (excluding scandium (Sc)) different from M1 as the rare earth metal element. Examples of 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 include at least Tm for the reason of infrared emission. It is more preferable that 10 mol% or more of M2 is Tm, and more preferably 50 mol% or more of M2 is Tm.

M3 includes boron (B), aluminum (Al), gallium (Ga), indium (In), scandium (Sc), silicon (Si), germanium (Ge), titanium (Ti), tin (Sn), and zirconium (Sn). Zr), and one or more metal elements selected from hafnium (Hf). It is preferable to contain at least Al or Ga, and 10 mol% or more of M3 is more preferably Al and / or Ga, and even more preferably Al or Ga, for the reason that the sensitizer is easily activated.

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

O represents oxygen and may be partially substituted with another element as long as the effect of the infrared phosphor according to this embodiment is not impaired. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N) and the like.

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

[Preferable Aspect 1-2]
As another preferred embodiment of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and has a wavelength. Examples thereof include phosphors characterized by having an emission peak wavelength between 750 and 950 nm. The crystal phase is preferably a crystal phase having a garnet structure.
(M1 _ab M2 _b ) ₃ (M3 _cd 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 (excluding Sc) that require Tm and are 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 and Mn.
O indicates oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.

In this embodiment, except for the following description of M2 and M4, the above description of "Preferable Phase 1-1" is incorporated.
M2 represents one or more rare earth metal elements (excluding scandium (Sc)) that require thulium (Tm) and are different from M1 as the rare earth metal element.
Examples of such rare earth metal elements include cerium (Ce) and europium (Eu), and the element is not particularly limited as long as it is an element different from M1, but Tm is essential for the reason of infrared emission, and 10 mol% of M2. It is more preferable that the above is Tm, and it is further preferable that 50 mol% or more of M2 is Tm.
M4 represents one or more metal elements selected from chromium (Cr) and manganese (Mn). For the reason that it easily absorbs ultraviolet light and visible light, it is preferable to contain at least Cr or Mn, and 10 mol% or more of M4 is preferably Cr and / or Mn, and more preferably Cr or Mn. Further, it is preferable that the amount of metal elements having magnetic properties such as iron (Fe) is 50 mol% or less.

[Preferable Aspect 1-3]
In the fluorescent substance according to the preferred embodiment 1-2, it is more preferable that M2 is Tm in the above formula (1-2). 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 the wavelengths of 750 and 950 nm. It is a Tm ³⁺ activated infrared fluorescent substance characterized by having.
(M1 _ab M2 _b ) ₃ (M3 _cd 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 indicates oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5.

In this embodiment, except for the following description of M2 and M4, the above description of "Preferable Phase 1-1" is incorporated.
M2 indicates Tm. By having Tm as an activating element, it is possible to obtain a high quality infrared phosphor having an emission peak between wavelengths of 750 and 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 preferably Cr. Cr and Mn are strongly absorbed in ultraviolet light or visible light, and are particularly preferable as sensitizers for Tm to act as luminescent ions, and energy transition is possible with high efficiency when combined with Tm.

[Preferable Aspect 2-1]
As another preferred embodiment of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (2-1), absorbs ultraviolet light or visible light, and has a wavelength. Examples thereof include phosphors characterized by having an emission peak wavelength between 750 and 950 nm. The crystal phase is preferably a crystal phase having 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 requires Tm or Nd.
A3 represents one or more metal elements selected from Mg, Co, and Zn.
A4 comprises one or more metal elements selected from Cr, Mn, Ni, Fe, and Cu, which require Cr or Mn, and B, Al, Ga, In, Si, Ge, Ti, Sn, Zr, And two or more metallic elements, including one or more metallic elements selected from Hf.
O indicates oxygen,
0 <a ≦ 0.5 and 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), lanthanum (La), etc., but it is preferable to contain at least La because of the cheapness of the raw material, and 50 of A1. More preferably, La is more than mol%, more preferably 80 mol% or more of A1 is La, and particularly preferably A1 is La.
Examples of alkaline earth metal elements other than Mg include calcium (Ca), strontium (Sr), and barium (Ba).
A1 may be partially substituted with another element as long as the effect of the infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and the like.

A2 represents one or more metal elements different from A1 as the rare earth metal element, which requires at least thulium (Tm) or neodymium (Nd). By having Tm or Nd as the activating element, it is possible to obtain a high quality infrared phosphor having an emission peak in the wavelength range of 750 to 950 nm. Further, when the activating element contains one or more metal elements such as cerium (Ce) and europium (Eu), which are different from A1 as the rare earth metal element, these act as sensitizers and are desired. It is possible to enhance the light emission at the wavelength.

A3 represents one or more metal elements selected from magnesium (Mg), cobalt (Co), and zinc (Zn). It is preferably contained at least Mg or Zn because it is not a heavy metal and has low toxicity, more preferably 10 mol% or more of A3 is Mg and / or Zn, further preferably Mg or Zn, and in Mg. It is particularly preferable to have.

A4 is one or more metal elements selected from chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe) and copper (Cu), which require 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 metallic elements, including one or more metallic 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 are strongly absorbed in ultraviolet light or visible light, and are particularly preferable as sensitizers for Tm to act as luminescent ions, and energy transition is possible with high efficiency when combined with Tm. A4 preferably contains Cr or Mn, and more preferably contains Mn. 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 total amount of Cr and Mn. Is more preferable.

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

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

O represents oxygen and may be partially substituted with another element as long as the effect of the infrared phosphor according to this embodiment is not impaired. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N) and the like.

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

[Preferable Aspect 3-1]
As another preferred embodiment of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (3-1), absorbs ultraviolet light or visible light, and has a wavelength. Examples thereof include phosphors characterized by having an emission peak wavelength between 750 and 1000 nm. The crystal phase is preferably a crystal phase having a magnet plumbit structure.
(D1 _1-a-b D2 _a D3 _b ) (D4 _1-a D5 _{11 + a-c} 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 represents one or more rare earth metal elements (excluding Sc) that are different from D1 as a rare earth metal element that requires Tm.
D4 contains one or more metal elements selected from Mg and Zn and contains.
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 indicates oxygen,
0 ≦ a ≦ 0.99, 0 <b ≦ 0.2, 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), gadrinium (Gd), lutetium (Lu), lanthanum (La), and the like, but at least because of the cheapness of raw materials. It is preferable to contain La, 50 mol% or more of D1 is more preferably La, 80 mol% or more of D1 is more preferably La, and D1 is particularly preferably La.
In addition, D1 may be partially substituted with another element as long as the effect as an infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and the like.

D2 represents one or more metal elements selected from calcium (Ca), strontium (Sr), and barium (Ba). It is preferable to contain at least Ca or Sr, more preferably 10 mol% or more of D2 is Ca and / or Sr, and 50 mol% or more of D2 is Ca or It is more preferably Sr.

D3 represents one or more rare earth metal elements (excluding scandium (Sc)) that are different from D1 as a rare earth metal element and require thulium (Tm). By having Tm as an activating element, it is possible to obtain a high quality infrared phosphor having an emission peak between wavelengths of 750 and 1000 nm. One or more rare earth metal elements (excluding Sc) different from D1 as a rare earth metal element include terbium (Ce), placeodium (Pr), neogenium (Nd), samarium (Sm), and europium (Eu). ), Terbium (Tb), disprosium (Dy), holomium (Ho), erbium (Er), itterbium (Yb) and the like. When such an element is contained in addition to Tm as the activating element, these act as sensitizers and can enhance 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 being Mg, and further preferably 50 mol% or more of Mg. It is preferable that D4 is Mg, and it is particularly preferable.

D5 represents one or more metal elements selected from aluminum (Al), gallium (Ga), indium (In), and scandium (Sc), and more preferably 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), with 10 mol% or more of D6 being Cr or Mn. More preferably, 20 mol% or more is preferably Cr or Mn, and 50 mol% or more is particularly preferably Cr or Mn.

O represents oxygen and may be partially substituted with another element as long as the effect of the infrared phosphor according to this embodiment is not impaired. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N) and the like.

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

[Preferable Aspect 4-1]
As another preferred embodiment of the infrared phosphor according to the first embodiment, it contains a crystal phase having a chemical composition represented by the following formula (4-1), absorbs ultraviolet light or visible light, and has a wavelength. Examples thereof 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 type 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 indicates 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 the rare earth metal element include lanthanum (La), gadolinium (Gd), lutetium (Lu), etc., but it is preferable to contain at least La because of the cheapness of the raw material, and 40 mol% or more of E1 is La. More preferably, 60 mol% or more of E1 is La, and E1 is particularly preferably La.
E1 may be partially substituted with another element as long as the effect as an infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and the like.

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

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

O represents oxygen and may be partially substituted with another element as long as the effect of the infrared phosphor according to this embodiment is not impaired. Examples of other elements include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), sulfur (S), nitrogen (N) and the like.

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

The phosphor according to this aspect is suitable for infrared emission in the above range even when Cr ³⁺ , which has not exhibited infrared emission at a suitable wavelength in the conventional phosphor, is used as the activated ion. It is excellent in that it has. It is not clear how the emission wavelength of the activated ion is adjusted in the phosphor having the chemical composition represented by the above formula (4-1), but the E2 site activated by Cr ³⁺ has a different valence. It is considered that it is shared by a plurality of metal cations and that the volume and symmetry of the polyhedron formed by the anion coordinated to Cr ³⁺ are related.

[Preferable Aspect 5-1]
As another preferred embodiment of the infrared fluorescent substance according to the first embodiment, a crystal phase having divalent sumalium (Sm) and trivalent turium (Tm) as active elements is contained in the matrix crystal, and the ultraviolet light is ultraviolet. Examples thereof include phosphors characterized by absorbing light of light or visible light and having an emission peak wavelength between wavelengths of 750 and 1000 nm.

[Preferable Aspect 5-2]
In the phosphor according to the preferred embodiment 5-1, the parent crystal is one or more elements selected from the group consisting of an alkali metal element and an alkaline earth metal element, 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). It is more preferable to further contain one or more elements selected from.

[Preferable Aspect 5-3]
Further, the fluorescent substance according to the preferred embodiment 5-1 or the fluorescent substance according to the preferred embodiment 5-2 contains a crystal phase in which the parent crystal has a chemical composition represented by the following formula (5-1). It is more preferable that it is a fluorescent substance.
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 that require Sm and Tm.
G3 represents two or more metallic elements selected from B, Al, Ga, Si, Ge and P.
O indicates 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. And / or Ba is more preferred, and 90 mol% or more is Sr and / or Ba. In addition, G1 may be partially substituted with another element as long as the effect as an infrared phosphor according to this embodiment is not impaired. Examples of other elements include sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and the like.
G2 represents two or more rare earth metal metal elements that require Sm and Tm, 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. Is more preferable, and it is particularly preferable that 90 mol% or more is B and P.

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

The light emitting device according to the second embodiment has a semiconductor light emitting element described later as a first light emitting body (excitation light source) and a second light emitting body that emits infrared light by irradiation of light from the first light emitting body. 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 the wavelengths of 700 and 1000 nm, and the waveform of the emission peak is A light emitting device including an infrared phosphor having a half-value 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]
As a specific embodiment of the infrared phosphor according to the present embodiment, the above-mentioned first embodiment is incorporated.
In the infrared phosphor according to the present embodiment, the emission peak wavelength in the infrared region is between 700 and 1000 nm, and the half-value width of the emission peak waveform is less than 60 nm. Among the elements selected from rare earth metal elements and transition metal elements, it is preferable to contain at least two or more elements. This is because when the infrared phosphor emits light using ultraviolet light or visible light emitted from a semiconductor light emitting element as excitation light, it is difficult to extend the wavelength to a desired emission wavelength with only one type of activating element. It depends. Therefore, as the activating element, it is preferable to use a combination of an element that acts as a sensitizer and an element that acts as a luminescent ion that is excited by the energy supplied from the sensitizer and emits light.

Among the activating elements, examples of the element acting as a sensitizer include Ce, Eu, Cr, Mn, Cu, and Sm. Examples of the element that acts as a luminescent ion include Tm and Nd. By appropriately combining these, an infrared phosphor having high luminous efficiency can be obtained without losing the excitation energy from the semiconductor light emitting device. From the viewpoint of the wavelength of the emission peak of the infrared phosphor, it is more preferable to contain at least thulium (Tm) as an activating element and further contain 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 luminescent ion.

Further, it is preferable that the activating element other than Tm is at least one element among Cr, Mn and Cu. These elements are particularly preferable as a sensitizer for absorbing visible light from ultraviolet light and for Tm to act as luminescent ions, and when combined with Tm, energy transition is possible with high efficiency. Of these, the most preferable combination is that the activating element is Tm and Cr.

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

[Configuration of light emitting device]
The configuration of the light emitting device is limited except that the light emitting device has a first light emitting body (excitation light source) and at least the infrared phosphor according to the above-described embodiment is used as the second light emitting body. However, it is possible to arbitrarily adopt a known device configuration.
Examples of the device configuration and the embodiment of the light emitting device include those described in JP-A-2007-291352.
In addition, as the form of the light emitting device, a cannonball type, a cup type, a chip-on-board, a remote phosphor, and the like can be mentioned.

{Use of light emitting device}
The application of the light emitting device is not particularly limited, and it can be used in various fields in which a normal infrared light emitting device is 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 transmission element such as a photoelectric switch or a video game joystick can also be used.

{Semiconductor light emitting device}
The semiconductor light emitting element included in the light emitting device according to the present 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 widely used as a semiconductor light emitting element, the price is low and it is easily available. Therefore, the emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting element is between the wavelengths of 300 to 700 nm. Is preferable. The wavelength is more preferably 300 to 650 nm or 350 to 680 nm, still more preferably 300 to 400 nm, 420 to 600 nm, 420 to 480 nm or 600 to 650 nm.

<Manufacturing method of phosphor>
The method for producing an infrared phosphor according to the first embodiment includes a step of mixing raw materials such as chloride, fluoride, oxide, carbonate and nitrate of each element, a step of firing, a step of crushing, and the like. It can include a step of cleaning and classification.

[Fluorescent material]
As the fluorescent material raw material used in the method for producing a fluorescent substance according to the first embodiment, known ones shall be used as long as the effect of the fluorescent substance according to the first embodiment produced by the present embodiment is not impaired. Can be done. For example, chlorides, fluorides, oxides, carbonates, nitrates and the like of each element can be used, but the present invention is not limited thereto.

[Mixing process]
The fluorescent material may be weighed so that the desired composition can be obtained, sufficiently mixed using a ball mill or the like, filled in a container, fired at a predetermined temperature and in an atmosphere, and the fired product may be pulverized and washed. For example, 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 target composition formula.

The 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 and the like.
As a wet mixing method, for example, a solvent or a dispersion medium is added to the above-mentioned fluorescent material, and the mixture is mixed using a milk pot and a milk stick to prepare a solution or a slurry, and then spray-dried, heat-dried, or naturally dried. It is a method of drying by the like.
Examples of the solvent or dispersion medium include acetone, methanol, ethanol, 1-propanol, 1-butanol and the like, and ethanol is preferable. The wet mixing time is usually 5 minutes or longer, preferably 15 minutes or longer, and more preferably 30 minutes or longer. Further, the mixing may be repeated a plurality of times, and is usually once or more, preferably twice or more, and more preferably three times or more. In particular, mixing for 15 minutes or more or mixing twice or more is preferable because the fluorescent substance according to the first embodiment of the present invention can be obtained as the main phase.

[Baking process]
The obtained mixture is filled in a container made of a material having low reactivity with each fluorescent material. The material of the container used at the time of such firing is not particularly limited as long as the effect of the fluorescent substance according to the first embodiment produced by the present embodiment is not impaired, and examples thereof include a container made of alumina.
The firing temperature varies depending on other conditions such as pressure, but usually firing can be performed 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 in a temperature range of 1400 ° C. or higher and 1600 ° C. or lower may be preferable because the fluorescent substance according to the first embodiment of the present invention may be obtained as the main phase.

If the calcination temperature is too high, defects in the crystal structure tend to be induced due to atomic defects in the phosphor, and the emission characteristics tend to be significantly deteriorated. If the firing temperature is too low, the progress of the solid phase reaction tends to be slowed down. It may be difficult for the production and grain growth to proceed.
The pressure during the firing step varies depending on the firing temperature and the like, 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 calcination atmosphere in the calcination step is arbitrary as long as a desired phosphor can be obtained, and specific examples thereof include an atmospheric atmosphere, a nitrogen atmosphere, a reduction atmosphere containing hydrogen or carbon, and the reduction atmosphere is preferable. The number of firings is arbitrary as long as a desired phosphor can be obtained, but the number of firings may be not particularly limited as long as the desired phosphor can be obtained, but the obtained fired body may be crushed and then fired again. Further, when firing a plurality of times, the atmosphere of each firing may be different.

The firing time varies depending on the temperature and pressure at the time of firing, but is usually 1 minute or longer, preferably 30 minutes or longer, and usually 72 hours or shorter, preferably 12 hours or shorter. If the firing time is too short, the particles will not grow, so it will not be possible to obtain a phosphor with good characteristics, and if the firing time is too long, the volatilization of the constituent elements will be promoted, resulting in defects in the crystal structure due to atomic defects. Is induced and a phosphor having good characteristics cannot be obtained.

[Washing process]
It may have a step (cleaning step) of washing the phosphor obtained by firing before dispersion and classification.
Impurities mainly unreacted residues used when synthesizing phosphors and unreacted raw materials tend to remain in the phosphors, and side reactions and the like tend to be generated in the phosphor slurry. ..
In order to improve the characteristics, 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 produced phosphor can be washed with an arbitrary solution, 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. The cleaning liquid may be impregnated with a reducing agent such as hydrogen peroxide, or the cleaning liquid may be heated and cooled within a range that does not significantly deteriorate the light emission characteristics.

The time for immersing the phosphor in the cleaning liquid varies depending on the stirring conditions and the like, but is usually 10 minutes or more, preferably 1 hour or more, and usually 72 hours or less, preferably 48 hours or less. Further, the washing may be performed a plurality of times, or the type and concentration of the washing liquid may be changed.
In the cleaning step, the fluorescent substance can be produced by immersing the fluorescent substance in the washing process, filtering the fluorescent substance, and drying the fluorescent substance. In addition, washing with ethanol, acetone, methanol, or the like may be inserted in the middle.

{Fluorescent compound-containing composition}
The fluorescent substance according to the first embodiment can also be used by mixing with a liquid medium. In particular, when the phosphor according to the first embodiment is used for an application such as a light emitting device, it is preferable to use the phosphor in a form dispersed in a liquid medium.

[Fluorescent material]
When it is contained in the composition containing the fluorescent substance according to the first embodiment, the type of the fluorescent substance is not limited and can be arbitrarily selected from the fluorescent substances according to the first embodiment described above. Further, the fluorescent substance may be used alone or in any combination and ratio of two or more. Further, the composition may contain a fluorescent substance other than the fluorescent substance according to the first embodiment as long as the effect of the fluorescent substance 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 the performance of the phosphor according to the first embodiment is not impaired within a target range. For example, any inorganic material and / or organic as long as it exhibits liquid properties under desired conditions of use, preferably disperses the phosphor according to the first embodiment, and does not cause an unfavorable reaction. A system material can be used, and examples thereof include silicone resin, epoxy resin, and polyimide silicone resin.

[Liquid medium and fluorophore content]
The content of the fluorophore and the liquid medium according to the first embodiment in the composition is arbitrary as long as the effect of the fluorophore according to the first embodiment is not significantly impaired, but for the liquid medium, the composition. It 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 whole product.

[Other ingredients]
In addition to the fluorescent substance and the liquid medium, other components may be contained in the composition as long as the effect of the fluorescent substance according to the first embodiment is not significantly impaired. Further, as the other components, only one kind may be used, or two or more kinds may be used in any combination and ratio.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.
The values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in each embodiment of the present invention, and the preferable range is the value of the upper limit or the lower limit. And may be in the range specified by the combination of 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, it is irradiated with excitation light of 455 nm at room temperature (25 ° C.) and is 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. Emission spectra within the wavelength range of Examples 3-1 to 3-3, 4-1 and 4-2) were obtained. 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 spectrum of the infrared light emitting device was measured using a small fiber optical spectroscope USB2000 (manufactured by Ocean Optics). More specifically, the light emitting device was turned on, and the light emitting spectrum of the light emitting device was obtained in the 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 wavelength 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 Examples 3-1 to 3-3, 4-1 and 4-2) were obtained.

[Powder X-ray diffraction measurement]
The powder X-ray diffraction was precisely measured by 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
Divergence slit = automatic detector = semiconductor array detector LYNXEYE, using Cu filter Scanning range 2θ = 5 to 90 degrees (in the case of Comparative Example 1-1, Example 1-1), or 5 to 90 degrees (Comparative Example 2- 1. In the case of Example 3-1 to Example 3-3, Example 4-1 and Example 4-2)
Reading width = 0.025 degrees

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

(Comparative Example 1-1: Production of Fluorescent Material)
The raw materials were blended so that the fluorescent substance obtained after the synthesis was Y _2.97 Tm _0.03 Ga ₅ O ₁₂ , and YGG: Tm ^{3 +} fluorescent substance was prepared.
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 Tm ₂ O ₃ powder (manufactured by Shin-Etsu Chemical Co., Ltd.) as raw materials. TM-04-001) was used. Each raw material was weighed so that the molar ratio of cations was Y: Ga: Tm = 2.97: 5.00: 0.03. After adding ethanol in an alumina mortar, these raw materials are wet-mixed, and after the ethanol is naturally dried, they are placed in an alumina container, and the container containing the mixed raw materials is placed in a small electric furnace (Motoyama Superburn). The calcined product was obtained by heating at 1500 ° C. for 8 hours in the air. A fluorescent substance was obtained by crushing the calcined product 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 by thin lines. 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 fluorescent substance)
YGG: Cr ³⁺ , Tm ³⁺ phosphors were prepared by blending the raw materials so that the fluorescent substance obtained after the 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.), Cr ₂ O ₃ powder (B58840N manufactured by Kishida Chemical Co., Ltd.) as raw materials. , And Tm ₂ O ₃ powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.). 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, as in Comparative Example 1-1. The mixture was mixed and heated to obtain a phosphor.

The XRD pattern obtained by performing powder X-ray diffraction measurement on this phosphor is shown in FIG. 1-3. It can be seen that this phosphor is composed of single-phase YGG. The emission spectrum of this phosphor is shown in FIG. 1-1, and the excitation spectrum is shown in FIG. 1-2 with thick lines. 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 fluorescent substance of this example has a strong infrared emission peak around 800 nm, which is 6 times or more in intensity as that of the fluorescent substance 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. rice field. The half-value width of the waveform of the emission peak was measured by regarding these overlapping emission peaks as one emission peak. 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. Further, from FIG. 1-2, it can be seen that the phosphor of this embodiment is excited by light in a wide wavelength band from blue to red and emits infrared light.
Further, the minimum reflectance R1 (%) between the wavelengths of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelengths of 700 and 800 nm of the present phosphor were measured, and the difference R1-R2 was measured. (%) Was calculated. The results are shown in Table 1.

(Example 1-2: Manufacture of light emitting device)
YGG: An infrared light emitting device was manufactured by combining Cr ³⁺ , Tm ³⁺ and a blue LED.
The fluorescent material 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 was phosphor: thermosetting silicone resin = 15:85. These raw materials were mixed using V-mini300 manufactured by EME, applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko KK), and cured to obtain a light emitting device. The emission spectrum of the light emitting device is shown in FIG. 1-4. It can be seen that the light emitting device has a peripheral infrared emission peak at about 800 nm.

(Comparative Example 2-1: Production of Fluorescent Material)
The raw materials were blended so that the phosphor obtained after the synthesis was La _1.98 Tm _0.02 MgGeO ₆ , and a La ₂ MgGeO ₆ : Tm ^{3 +} phosphor was prepared.
Commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Industries, Ltd.), MgO powder (LKG5947 manufactured by Wako Pure Chemical Industries, Ltd.), GeO ₂ powder (3138286 manufactured by High Purity Chemical Research Institute), and Tm ₂ O ₃ as raw materials. A powder (TM-04-001 manufactured by Shin-Etsu Chemical Industries, 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. After adding ethanol in an alumina mortar, these raw materials are wet-mixed, and after the ethanol is naturally dried, they are placed in an alumina container, and the container containing the mixed raw materials is placed in a small electric furnace (Motoyama Superburn). The calcined product was obtained by heating at 1400 ° C. for 8 hours in the air. A fluorescent substance was obtained by crushing the calcined product 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 by thin lines. 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 fluorescent substance)
La ₂ MgGeO ₆ : Mn ⁴⁺ , Tm ³⁺ phosphors were prepared by blending the raw materials so that the phosphor obtained after the 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 Junyaku Co., Ltd.), GeO ₂ powder (313826 manufactured by High Purity Chemical Research Institute), 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 High Purity Chemical Research Institute) 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. Mixing and heating in the same manner as in -1, a phosphor was obtained.

The XRD pattern obtained by performing powder X-ray diffraction measurement on this phosphor is shown in FIG. 2-3. It can be seen that this phosphor is composed of a single-phase La ₂ MgGeO ₆ .
The emission spectrum of this phosphor is shown in FIG. 2-1 and the excitation spectrum is shown in FIG. 2-2 with thick lines. 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. Further, from FIG. 2-2, it can be seen that the phosphor of this embodiment is excited by light in a wide wavelength band from ultraviolet to blue and emits infrared light.
Further, the minimum reflectance R1 (%) between the wavelengths of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelengths of 700 and 800 nm of the present phosphor were measured, and the difference R1-R2 was measured. (%) Was calculated. The results are shown in Table 1.

(Example 2-2: Production of fluorescent substance)
The raw materials were blended so that the phosphor obtained after the synthesis was La _1.98 Tm _0.02 MgTi _0.99 Mn _0.01 O ₆ , and La ₂ MgTIO ₆ : Mn ⁴⁺ , Tm ³⁺ phosphors were prepared. ..
Commercially available La ₂ O ₃ powder (LA-04-153 manufactured by Shin-Etsu Chemical Co., Ltd.), Mg (OH) ₂ powder (83480D manufactured by High Purity Chemical Research Institute), TiO ₂ powder (LAG1626 manufactured by Wako Pure Chemical Industries, Ltd.), Tm ₂ as raw materials. O ₃ powder (TM-04-001 manufactured by Shin-Etsu Chemical Co., Ltd.) and MnO ₂ powder (194474 manufactured by High Purity Chemical Laboratory) 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, it was mixed and heated in the same manner as in Example 2-1 to obtain a fluorescent substance.
The XRD pattern obtained by performing powder X-ray diffraction measurement on this phosphor is shown in FIG. 2-6. It can be seen that this fluorophore is composed of single-phase La ₂ MgTIO ₆ .
The emission spectrum of this phosphor is shown by a thick line in FIG. 2-4, and the excitation spectrum is shown by a thick line in FIG. 2-5. 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. Further, from FIG. 2-5, it can be seen that the phosphor of this embodiment is excited by light in a wide wavelength band from ultraviolet to blue and emits infrared light.

(Example 2-3: Manufacture of light emitting device)
An infrared light emitting device was produced by combining La ₂ MgGeO ₆ : Mn ⁴⁺ and Tm ³⁺ , which are the phosphors obtained in Example 2-1 and a blue LED.
The fluorescent material 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 was phosphor: thermosetting silicone resin = 15:85. These raw materials were mixed using V-mini300 manufactured by EME, applied to a package equipped with a commercially available blue LED (manufactured by Showa Denko KK), and cured to obtain a light emitting device. The emission spectrum of the light emitting device is shown in FIG. 2-7. It can be seen that the light emitting device has an infrared emission peak around about 800 nm.

(Example 2-4: Manufacture of light emitting device)
An infrared light emitting device was produced by combining La ₂ MgTIO ₆ : Mn ⁴⁺ and Tm ³⁺ , which are the phosphors obtained in Example 2-2, with a blue LED.
The fluorescent material obtained in Example 2-2 and the thermosetting silicone resin were used as raw materials. Other than that, weighing, coating, and curing were performed 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 FIG. 2-8. It can be seen that the light emitting device has an infrared emission peak around about 800 nm.

(Example 3-1: Production of fluorescent substance)
LaMgAl ₁₁ O ₁₉ : Cr ³⁺ , Tm ³⁺ phosphors were prepared by blending the raw materials so that the phosphor obtained after the synthesis was La _0.95 Tm _0.05 MgAl _10.67 Cr _0.33 O ₁₉ . ..
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Industries, Ltd.), MgO powder (manufactured by Wako Pure Chemical Industries, Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Industries, Ltd.), Cr ₂ O ₃ powder (Kishida) as raw materials (Manufactured by Kagaku Co., Ltd.) and Tm ₂ O3 powder ₍ manufactured by Shin-Etsu Chemical Industries, 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 adding 5 wt% of H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) to these raw materials externally, ethanol is added in an alumina mortar, then wet mixed, and the ethanol is naturally dried before being made of alumina. The container containing the mixed raw material 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 fluorescent substance was obtained by crushing the calcined product in an alumina mortar until there were no large lumps.
Further, the minimum reflectance R1 (%) between the wavelengths of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelengths of 700 and 800 nm of the present phosphor were measured, and the difference R1-R2 was measured. (%) Was calculated. The results are shown in Table 1.

The emission spectrum of the obtained phosphor is shown by a solid line in FIG. 3-1 and the excitation spectrum is shown by a dotted line in FIG. 3-2. 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. Further, from FIG. 3-2, it can be seen that the phosphor of this embodiment 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 performing the 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 fluorescent substance)
Example 3-2 in the same manner as in Example 3-1 except that the raw materials were blended so that the phosphor obtained after the synthesis was La _0.95 Tm _0.05 MgAl _10.89 Cr _0.11 O ₁₉ . Fluorescent material was obtained. Based on the emission spectrum 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 having a narrow half-value width at 801 nm.

(Example 3-3: Production of fluorescent substance)
Example 3-3 in the same manner as in Example 3-1 except that the raw materials were blended so that the phosphor obtained after the synthesis was La _0.99 Tm _0.01 MgAl _10.67 Cr _0.33 O ₁₉ . Fluorescent material was obtained. According to the emission spectrum 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-value width at 798 nm.

(Example 4-1: Production of fluorescent substance)
The raw materials were blended so that the fluorescent substance obtained after the synthesis was La ₅ Al _0.99 Cr _0.01 Ti ₃ O ₁₅ , and a La ₅ AlTi ₃ O ₁₅ : Cr ^{3 +} fluorescent substance was prepared.
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Research Institute), TiO ₂ powder (manufactured by Furuuchi Chemical Co., Ltd.), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), Cr ₂ O ₃ powder (Kishida Chemical Co., Ltd.) as raw materials Made by the company) 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. H ₃ BO ₃ powder (manufactured by Wako Pure Chemical Industries, Ltd.) is externally added to these raw materials in an amount of 2 wt%, then ethanol is added in an alumina mortar, wet-mixed, and the ethanol is naturally dried before being made of alumina. The container containing the mixed raw material 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 fluorescent substance was obtained by crushing the calcined product 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. 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. Further, from FIG. 4-2, it can be seen that the phosphor of this embodiment 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 753 nm was 41 nm.

The XRD pattern obtained by performing the powder X-ray diffraction measurement of the phosphor of this example is shown in FIG. 4-3. It can be seen that the fluorophore of this example mainly consists of La ₅ AlTi ₃ O ₁₅ . The peak indicated by the arrow in FIG. _4-3 is LaAlO3 by-produced as an impurity phase. The peak intensity in FIG. 4-3 is small, and LaAlO ₃ : Cr emission usually has a maximum emission peak at about 737 nm and a plurality of weak emission peaks between 735 nm and 755 nm. Therefore, it can be said that the infrared emission peak with a narrow half width of 753 nm observed above is derived from La ₅ AlTi ₃ O ₁₅ .
Further, the minimum reflectance R1 (%) between the wavelengths of 350 and 700 nm and the minimum reflectance R2 (%) between the wavelengths of 700 and 800 nm of the present phosphor were measured, and the difference R1-R2 was measured. (%) Was calculated. The results are shown in Table 1.

(Example 4-2: Production of fluorescent substance)
The raw materials were blended so that the phosphor obtained after the synthesis was La ₅ Al _0.95 Cr _0.05 Ti ₃ O ₁₅ , and La ₅ AlTi ₃ O ₁₅ : Cr ^{3 +} phosphor was prepared.
Commercially available La (OH) ₃ powder (manufactured by High Purity Chemical Research Institute), TiO ₂ powder (manufactured by Showa Denko), Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd.), Cr ₂ O ₃ powder (manufactured by Kishida Chemical Co., Ltd.) as raw materials Made) 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 mix, let the ethanol air dry, put it in an alumina container, and install the container containing the mixed raw material in a small electric furnace (Motoyama Superburn). A fired body was obtained by heating at 1600 ° C. in the air for 8 hours. A fluorescent substance was obtained by crushing the calcined product in an alumina mortar until there were no large lumps.
According to the emission spectrum 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 having a narrow half-value width at 752 nm.

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

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

Claims (5)

It contains a crystal phase having a chemical composition represented by the following formula (1-2), absorbs ultraviolet light or visible light, and has an emission peak wavelength between the wavelengths of 750 and 950 nm. Fluorescent material.
(M1 _ab M2 _b ) ₃ (M3 _cd 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 (excluding Sc) that require Tm and are 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 and Mn.
O indicates oxygen,
0 <a <1, 0 <b ≦ 0.5, 0 <c <1, 0 <d ≦ 0.5 ,
M1 contains at least Y and
M3 contains at least Ga and
M4 contains at least Cr . The fluorescent substance according to claim 1, wherein the crystal phase is a crystal phase having a garnet structure. Semiconductor light emitting devices that emit ultraviolet light or visible light,
A light emitting device including a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light emitting element and emits light in the infrared region.
The fluorescent substance that emits light in the infrared region includes the fluorescent substance according to claim 1 or 2 .
A light emitting device characterized in that the emission peak wavelength in the infrared region of the phosphor that emits light in the infrared region is between the wavelengths of 700 and 1000 nm, and the half width of the waveform of the emission peak is less than 60 nm. The minimum reflectance (%) of the phosphor emitting in the infrared region between the wavelengths of 350 and 700 nm is lower than the minimum reflectance (%) between the wavelengths of 700 and 800 nm, and the difference is 20. The light emitting device according to claim 3 , which is% or more. The light emitting device according to claim 3 or 4 , wherein the emission peak wavelength of ultraviolet light or visible light emitted from the semiconductor light emitting device is between wavelengths of 300 to 700 nm.

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