Near infrared phosphor, near infrared light-emitting device, spectroscopic device, and sensing device

Abstract

This near infrared phosphor has the same spinel-type crystal structure as MgGa2O4 and is obtained by adding a Cr ion to an inorganic compound represented by general formula (1).　(1): MAxpMB(2-2x+2y)qMC(4+x-4y)rqMD2ysO8 MA is at least one element from among group 1 elements and group 11 elements, MB is at least one element from among group 2 elements and group 12 elements, MC is at least one element from among group 3 elements and group 13 elements, MD is at least one element from among group 4 elements and group 14 elements, and the expressions 0.8≤p≤1.2, 0.8≤q≤1.2, 0.8≤r≤1.2, 0.8≤s≤1.2, 0.01≤x≤0.99, 0≤y≤0.99, and 0.01≤x+y≤0.99 are satisfied. A near infrared light-emitting device (100) comprises the near infrared phosphor. A spectroscopic device (200) and a sensing device comprise the near infrared light-emitting device.

Description

Near-infrared phosphor, near-infrared light emitting device, spectroscopic device and sensing device

[0001] The present disclosure relates to a near-infrared phosphor, a near-infrared light emitting device, a spectroscopic device, and a sensing device.

[0002] Near-infrared light has the property of easily penetrating living organisms, making it suitable for obtaining information about the inside of a living organism and for treating lesions inside the living organism. Furthermore, because near-infrared light has the property of penetrating organic matter, it is also advantageous for inspecting the contents of unopened organic containers or foreign objects. Therefore, near-infrared light-emitting devices that emit near-infrared light are expected to be used for medical lighting and lighting for inspection equipment.

[0003] Such near-infrared light emitting devices use a near-infrared phosphor that is excited by excitation light emitted by a solid-state light emitting element and emits near-infrared light. １ and the second element M ２ and the third element M ３ The oxide phosphor has an emission spectrum with a peak wavelength in the range of 800 nm to 1600 nm. １．９５ O ４ : Cr ０．０５ and a phosphor having an emission peak wavelength of 890 nm is shown.

[0004] Patent Document 2 discloses an oxide phosphor having a composition included in the composition formula represented by the following formula: (Li １－ｔ M １ ｔ ) ｕ (Ga １－ｖ M ２ ｖ ) ５ O ｗ : Cr ｘ , Ni ｙ , M ３ ｚ (In the formula, M １ is at least one element selected from the group consisting of Na, K, Rb, and Cs, and M ２is at least one element selected from the group consisting of B, Al, Sc, In and rare earth elements, and M ３ is at least one element selected from the group consisting of Si, Ge, Sn, Ti, Zr, Hf, Bi, V, Nb and Ta, and t, u, v, w, x, y and z satisfy the following conditions: 0≦t≦1.0, 0.7≦u≦1.6, 0≦v<1.0, 7.85≦w≦11.5, 0.05≦x≦1.2, 0≦y≦0.5, 0.25<x+y≦1.2, y<x, 0≦z≦0.5.) Furthermore, in the examples of Patent Document 2, the charged composition is LiGa ５ O ８ : Cr ０．２８ and a phosphor having an emission peak wavelength of 840 nm.

[0005] JP 2022-182941 A JP 2023-80391 A

[0006] The present inventors have prepared the oxide phosphors of Patent Documents 1 and 2 and evaluated their fluorescent properties. As a result, it has been found that these oxide phosphors do not have sufficient fluorescent properties. Therefore, there is a demand for near-infrared phosphors with excellent fluorescent properties.

[0007] The present disclosure has been made in view of the problems inherent in the conventional techniques, and an object of the present disclosure is to provide a near-infrared phosphor having excellent fluorescent properties, a near-infrared light-emitting device including the near-infrared phosphor, and a spectroscopic device and a sensing device including the near-infrared light-emitting device.

[0008] In order to solve the above problems, the near-infrared phosphor according to the embodiment of the present disclosure is ２ O ４ MA is a phosphor having the same spinel-type crystal structure as that of the inorganic compound represented by the general formula (1) and having Cr ions added thereto. ｘｐ MB （２－２ｘ＋２ｙ）ｑ MC （４＋ｘ－４ｙ）ｒｑ MD ２ｙｓ O ８... (1) (In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements, MB is one or more elements selected from Group 2 elements and Group 12 elements, MC is one or more elements selected from Group 3 elements and Group 13 elements, MD is one or more elements selected from Group 4 elements and Group 14 elements, and p, q, r, s, x, and y satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦x≦0.99, 0≦y≦0.99, 0.01≦x+y≦0.99.)

[0009] A near-infrared light emitting device according to an aspect of the present disclosure includes the above-described near-infrared phosphor.

[0010] A spectroscopic device according to an aspect of the present disclosure includes the near-infrared light emitting device described above.

[0011] A sensing device according to an aspect of the present disclosure includes the near-infrared light emitting device described above.

[0012] FIG. 1 is a schematic diagram showing an example of a near-infrared light emitting device according to this embodiment. FIG. 2 is a schematic diagram showing another example of a near-infrared light emitting device according to this embodiment. FIG. 3 is a schematic diagram showing an example of a spectroscopic device according to this embodiment. FIG. 4 is a schematic diagram showing another example of a spectroscopic device according to this embodiment. FIG. 5 shows X-ray diffraction spectra of the phosphors of Examples 1-1 to 1-3 and Comparative Examples 1-4 to 1-5, as well as X-ray diffraction spectra of MgGa ２ O ４ and LiGa ５ O ８ FIG. 6 is a graph showing the X-ray diffraction spectra of the phosphors of Example 1-1 and Example 4-1. FIG. 7 is a graph showing the emission spectra of the phosphors of Example 1-1 and Comparative Examples 1-4 and 1-5 when excited at a wavelength of 450 nm. FIG. 8 is a graph showing the emission spectra of the phosphors of Example 1-1 and Example 8-2 when excited at a wavelength of 450 nm.

[0013] The near-infrared phosphor, near-infrared light emitting device, spectroscopic device, and sensing device according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0014] As mentioned above, Patent Document 1 discloses a MgGa １．９５ O ４ : Cr ０．０５ Furthermore, Patent Document 2 discloses a phosphor containing LiGa ５ O ８ : Cr ０．２８ The present inventors have disclosed a phosphor corresponding to the phosphor disclosed in Patent Document 1. ２ O ４ : 4% Cr and LiGa corresponding to the phosphor of Patent Document 2 ５ O ８ : 4% Cr was prepared and the fluorescent properties were evaluated. Furthermore, the concentration of Cr ions, which act as an activator, was standardized to 4 mol% in these phosphors. Furthermore, the crystal structures of these phosphors were measured by X-ray diffraction, and the XRD patterns were found to be nearly identical, indicating that these phosphors had the same crystal structure. The internal quantum efficiency (IQE), external quantum efficiency (EQE), and fluorescence peak wavelength of these phosphors were then measured.

[0015] As shown in Table 1, the phosphor of Patent Document 1 had an internal quantum efficiency of 37% and an external quantum efficiency of 19%. The phosphor of Patent Document 2 had an internal quantum efficiency of 46% and an external quantum efficiency of 25%, and thus had somewhat better fluorescent properties than the phosphor of Patent Document 1. However, the fluorescent properties of the phosphors of Patent Documents 1 and 2 cannot be said to be good at all, and further improvement is required.

[0016]

[0017] The near-infrared phosphor of this embodiment is a phosphor with better fluorescent properties than conventional near-infrared phosphors.

[0018] [Near-infrared phosphor] The near-infrared phosphor of this embodiment is a compound MgGa ２ O ４ The phosphor has the same spinel-type crystal structure as that of the phosphor shown in the above, and is formed by adding Cr ions to an inorganic compound represented by the following general formula (1): ｘｐ MB （２－２ｘ＋２ｙ）ｑ MC （４＋ｘ－４ｙ）ｒｑ MD ２ｙｓ O ８... (1) In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements. MB is one or more elements selected from Group 2 elements and Group 12 elements. MC is one or more elements selected from Group 3 elements and Group 13 elements. MD is one or more elements selected from Group 4 elements and Group 14 elements. Furthermore, p, q, r, s, x, and y satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦x≦0.99, 0≦y≦0.99, and 0.01≦x+y≦0.99.

[0019] The near-infrared phosphor of this embodiment is a compound MgGa ２ O ４ It has the same spinel-type crystal structure as MgGa ２ O ４ and LiGa ５ O ８ The near-infrared phosphor is a Cr-activated phosphor having a solid solution of MgGa as a host crystal. ２ O ４ and LiGa ５ O ８ It is also a Cr-activated phosphor having a host crystal with an intermediate composition between

[0020] In general formula (1), MA is a monovalent element and is one or more elements selected from elements of Group 1 and Group 11. Since both the elements of Group 1 and Group 11 are monovalent elements and have similar ionic radii in the same period, these elements can easily be substituted for each other.

[0021] MA may be an alkali metal, specifically at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Furthermore, MA is preferably at least one selected from the group consisting of lithium, sodium, and potassium, and is preferably lithium, sodium, or potassium. When MA is one of these elements, it becomes possible to improve the fluorescent properties of the wavelength-converted light emitted from the near-infrared phosphor, particularly the internal quantum efficiency and external quantum efficiency.

[0022] In general formula (1), MB is a divalent element and is one or more elements selected from elements of Group 2 and Group 12. Since both the elements of Group 2 and Group 12 are divalent elements and have similar ionic radii in the same period, these elements can easily be substituted for each other.

[0023] In addition, MB may be at least one of an alkaline earth metal and zinc, specifically at least one selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), and zinc (Zn). Furthermore, MB is preferably at least one selected from the group consisting of magnesium and zinc, and is preferably magnesium or zinc. When MB is one of these elements, it becomes possible to improve the fluorescent properties of the wavelength-converted light emitted from the near-infrared phosphor, particularly the internal quantum efficiency and external quantum efficiency.

[0024] In general formula (1), M C is a trivalent element and is one or more elements selected from elements of Group 3 and elements of Group 13. Since both elements of Group 3 and elements of Group 13 are trivalent elements and have similar ionic radii in the same period, these elements can easily be substituted for each other.

[0025] Note that MC may be at least one selected from the group consisting of scandium (Sc), yttrium (Y), lutetium (Lu), boron (B), aluminum (Al), gallium (Ga), and indium (In). Furthermore, MC is preferably at least one selected from the group consisting of gallium, boron, and aluminum, and is preferably gallium, boron, or aluminum. When MC is one of these elements, it becomes possible to improve the fluorescent properties of the wavelength-converted light emitted from the near-infrared phosphor, particularly the internal quantum efficiency and external quantum efficiency.

[0026] In general formula (1), MD is a tetravalent element and is one or more elements selected from elements of Group 4 and elements of Group 14. Since both the elements of Group 4 and Group 14 are tetravalent elements and have similar ionic radii in the same period, these elements can easily be substituted for each other.

[0027] The MD may be at least one selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb). Preferably, the MD is germanium. When the MD is one of these elements, it is possible to improve the fluorescent properties of the wavelength-converted light emitted from the near-infrared phosphor, particularly the internal quantum efficiency and external quantum efficiency.

[0028] In general formula (1), p, q, r, and s satisfy the following conditions: 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, and 0.8≦s≦1.2. However, it is more preferable that p, q, r, and s satisfy the following conditions: 0.9≦p≦1.1, 0.9≦q≦1.1, 0.9≦r≦1.1, and 0.9≦s≦1.1.

[0029] In general formula (1), x and y satisfy the following conditions: 0.01≦x≦0.99, 0≦y≦0.99, and 0.01≦x+y≦0.99. In other words, since x is 0.01 or more in general formula (1), MA, MB, and MC are essential constituent elements. However, since y is 0 or more in general formula (1), MD is an optional constituent element. Furthermore, when x and y are within these ranges, it is possible to improve the fluorescent properties, particularly the internal quantum efficiency and external quantum efficiency.

[0030] Here, in the general formula (1), when x = 0 and y = 0, the phosphor described in Patent Document 1 is included. However, as mentioned above, the MgGa ２ O ４ The LiGa:Cr phosphor has insufficient fluorescent properties and requires further improvement for practical use. In addition, when x = 1 and y = 0, the phosphor described in Patent Document 2 is included. However, as mentioned above, the LiGa:Cr phosphor described in Patent Document 2 ５ O ８The fluorescent properties of the Cr phosphor are also not very good.

[0031] However, the near-infrared phosphor of this embodiment is MgGa as described in Patent Document 1. ２ O ４ : Cr phosphor and LiGa described in Patent Document 2 ５ O ８ The near-infrared phosphor of this embodiment is not merely an intermediate value of the fluorescent properties of the Cr:Cr phosphors, but has fluorescent properties higher than those of these phosphors. Therefore, by combining the near-infrared phosphor of this embodiment with an excitation light source such as a solid-state light-emitting device, highly efficient near-infrared lighting can be provided. Furthermore, the enhanced fluorescent properties of the near-infrared phosphor make it possible to provide high-output near-infrared lighting even when the output of the excitation light source is reduced.

[0032] In general formula (1), x preferably satisfies 0.1≦x≦0.9, and more preferably 0.25≦x≦0.75. When x is within this range in general formula (1), the fluorescent properties of the fluorescence emitted from the near-infrared phosphor can be further improved.

[0033] In general formula (1), y preferably satisfies 0≦y≦0.33, and more preferably 0≦y≦0.1. Furthermore, x+y preferably satisfies 0.1≦x+y≦0.95, and more preferably 0.25≦x+y≦0.85.

[0034] The near-infrared phosphor of this embodiment absorbs excitation light emitted by a solid-state light-emitting element and converts it into wavelength-converted light containing near-infrared light. Furthermore, since the near-infrared phosphor contains chromium ions as an activator, it can absorb visible light, particularly blue or red light, and emit near-infrared light components. Therefore, the excitation light irradiated to the near-infrared phosphor is preferably blue light having a maximum intensity within a wavelength range of 430 nm to 480 nm. This configuration allows for highly efficient excitation of the near-infrared phosphor, resulting in a highly efficient near-infrared light-emitting device. Furthermore, the excitation light irradiated to the near-infrared phosphor may be red light having a maximum intensity within a wavelength range of 600 nm to 700 nm. This configuration allows for excitation of the near-infrared phosphor with relatively low energy red light, resulting in a near-infrared light-emitting device with minimal heat generation due to Stokes loss of the phosphor. The near-infrared phosphor preferably emits fluorescence when irradiated with excitation light having a wavelength of 450 nm.

[0035] In the near-infrared phosphor of this embodiment, the valence of the chromium ion serving as the activator is preferably trivalent. ３＋ and some of the chromium ions are Cr ４＋ Specifically, in the near-infrared phosphor, 95 atomic % or more of the emitting chromium ions may be Cr ３＋ 97 atomic % or more of the luminescent chromium ions may be Cr ３＋ may be.

[0036] In the near-infrared phosphor of this embodiment, the amount of chromium ions added as an activator is not particularly limited. However, the concentration of chromium in the near-infrared phosphor is preferably 0.03 mol% or more and 10.0 mol% or less, and more preferably 0.1 mol% or more and 5.0 mol% or less, based on the amount of metal element substance. The higher the chromium concentration in the near-infrared phosphor, the more easily the light absorptance improves, and the lower the chromium concentration, the more easily the internal quantum efficiency improves.

[0037] The near-infrared phosphor of this embodiment contains chromium ions as an activator in the inorganic compound represented by general formula (1). However, the near-infrared phosphor may contain, in addition to chromium ions, an activator other than chromium ions. Specifically, the near-infrared phosphor may contain, as an activator, nickel ions (Ni) in addition to chromium ions. ２＋ ) may be contained. By including nickel ions in addition to chromium ions in the inorganic compound represented by general formula (1), a near-infrared phosphor having a maximum fluorescence intensity at wavelengths of 1100 nm or more can be obtained. Therefore, by using this near-infrared phosphor, it is possible to provide near-infrared lighting with a wide band near the wavelength of 1300 nm and high efficiency.

[0038] In the near-infrared phosphor of this embodiment, the nickel ions serving as an activator have the property of absorbing the fluorescence emitted by the chromium ions and emitting fluorescence of a longer wavelength. Therefore, when the near-infrared phosphor contains nickel ions as an activator, the intensity of the fluorescence derived from the chromium ions may decrease.

[0039] In the near-infrared phosphor of this embodiment, the amount of nickel ions added as an activator is not particularly limited. However, the concentration of nickel in the near-infrared phosphor is preferably lower than the concentration of chromium. Specifically, the concentration of nickel in the near-infrared phosphor is preferably 0.03 mol% or more and 10.0 mol% or less, and more preferably 0.1 mol% or more and 5.0 mol% or less, based on the amount of metal element substance.

[0040] The spectral distribution of the fluorescence emitted by the near-infrared phosphor of this embodiment preferably has a maximum fluorescence intensity within a wavelength range of 800 nm to 1600 nm. This allows for use in determining the moisture content of food, evaluating the quality of fresh fish and meat, and analyzing resin components for the purpose of plastic sorting. Furthermore, the spectral distribution of the fluorescence emitted by the near-infrared phosphor of this embodiment may have a maximum fluorescence intensity within a wavelength range of 800 nm to 1000 nm, or may have a maximum fluorescence intensity within a wavelength range of 800 nm to 900 nm. This allows for the fluorescence emitted from the near-infrared phosphor to be detected with high sensitivity using a relatively inexpensive Si-based sensor.

[0041] The spectral distribution of the fluorescence emitted by the near-infrared phosphor of this embodiment may have a maximum fluorescence intensity value within a wavelength range of 1200 nm or more and 1600 nm or less. In this way, the fluorescence emitted by the near-infrared phosphor can be made into a form suitable for a light source for quality evaluation to check for scratches on semiconductors such as silicon wafers. Furthermore, the fluorescence emitted by the near-infrared phosphor can be made into a form suitable for a light source for sorting mixed plastics such as polyethylene and polystyrene.

[0042] In the fluorescence emitted by the near-infrared phosphor of this embodiment, the half-width of the spectrum having the maximum fluorescence intensity preferably exceeds 100 nm. This allows near-infrared light components having a spectral distribution over a wide wavelength range to be obtained using only one type of near-infrared phosphor, without using several types of near-infrared phosphors. The half-width of the spectrum may be 140 nm or more, 160 nm or more, 180 nm or more, or 200 nm or more. The half-width of the spectrum may also be 340 nm or less, 320 nm or less, 300 nm or less, or 280 nm or less.

[0043] The shape of the near-infrared phosphor of this embodiment is not particularly limited. However, the near-infrared phosphor may be either a powder phosphor or a fluorescent ceramic. Such a near-infrared phosphor is easily applied as a wavelength converter. A powder phosphor can be made into a wavelength converter by a simple method of mixing it with a transparent resin and curing it, so it is suitable for easily obtaining a wavelength converter. On the other hand, a fluorescent ceramic is a near-infrared phosphor obtained by sintering a powder phosphor. Such fluorescent ceramics are suitable as wavelength converters because they not only have excellent thermal conductivity but also a high optical absorptivity of excitation light.

[0044] As described above, the near-infrared phosphor of this embodiment is MgGa ２ O ４ The phosphor has the same spinel-type crystal structure as that of the phosphor shown in the above, and is formed by adding Cr ions to an inorganic compound represented by the following general formula (1): ｘｐ MB （２－２ｘ＋２ｙ）ｑ MC （４＋ｘ－４ｙ）ｒｑ MD ２ｙｓ O ８ ... (1) In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements. MB is one or more elements selected from Group 2 elements and Group 12 elements. MC is one or more elements selected from Group 3 elements and Group 13 elements. MD is one or more elements selected from Group 4 elements and Group 14 elements. p, q, r, s, x, and y satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦x≦0.99, 0≦y≦0.99, 0.01≦x+y≦0.99.

[0045] The near-infrared phosphor of this embodiment has such a composition, resulting in improved fluorescence characteristics compared to conventional near-infrared phosphors. As a result, a near-infrared light-emitting device can be obtained that can output high-power near-infrared light components suitable for near-infrared spectroscopy, as described below. Furthermore, the fluorescence emitted from the near-infrared phosphor of this embodiment can have a peak wavelength of 1000 nm or less, allowing the fluorescence to be detected with high sensitivity even with relatively inexpensive Si-based sensors. Therefore, the near-infrared phosphor can be applied to a wide range of quality analyses, such as evaluating the moisture content of food and the quality of fresh fish and meat. Furthermore, since the near-infrared phosphor of this embodiment has a fluorescence peak particularly in the wavelength range of 800 to 1000 nm, combining it with other near-infrared phosphors can produce a broad near-infrared spectrum. As a result, it becomes possible to produce lighting for near-infrared sensing with higher accuracy.

[0046] The near-infrared phosphor of this embodiment is a phosphor obtained by adding Cr ions to the inorganic compound represented by the general formula (1) as described above, but can also be expressed as follows.

[0047] The near-infrared phosphor of this embodiment is MgGa ２ O ４ The phosphor has the same spinel-type crystal structure as that of the inorganic compound represented by the general formula (2) below, and is obtained by adding Cr ions to the inorganic compound represented by the general formula (2): (2-2x-2y)MB １ MC ２ O ４ ・xMA １ MC ５ O ８ ・2yMB ２ MD １ O ４ ... (2) In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements. MB is one or more elements selected from Group 2 elements and Group 12 elements. MC is one or more elements selected from Group 3 elements and Group 13 elements. MD is one or more elements selected from Group 4 elements and Group 14 elements. x and y satisfy 0.01≦x≦0.99, 0≦y≦0.99, and 0.01≦x+y≦0.99.

[0048] The near-infrared phosphor of this embodiment is MB １ MC ２ O ４ and MA １ MC ５ O ８ and MB ２ MD １ O ４ Since the host crystal is an inorganic compound consisting of a solid solution of Cr and Cr, the inorganic compound can also be expressed as shown in general formula (2). ３＋ ), but may contain other activators other than chromium ions, for example, nickel ions (Ni ２＋ ) may be included.

[0049] [Near-infrared light emitting device] Next, a near-infrared light emitting device according to this embodiment will be described. The near-infrared light emitting device 100 according to this embodiment includes the near-infrared phosphor described above. Since the near-infrared phosphor of this embodiment has good fluorescent properties, the near-infrared light emitting device 100 can output high-power near-infrared light components suitable for near-infrared spectroscopy.

[0050] Fig. 1 schematically shows an example of a near-infrared light emitting device 100 according to this embodiment. As shown in Fig. 1, the near-infrared light emitting device 100 includes a solid-state light emitting element 1 and a wavelength converter 2. The wavelength converter 2 contains the above-mentioned near-infrared phosphor. The near-infrared light emitting device 100 is configured to emit output light 20 containing near-infrared light 21 emitted by the near-infrared phosphor.

[0051] The solid-state light-emitting element 1 is configured to emit primary light (excitation light) 10. The output light 20 may include the primary light 10. The primary light 10 is preferably blue light having a maximum intensity within a blue wavelength range of 435 nm or more and less than 480 nm, particularly 440 nm or more and less than 470 nm. When a near-infrared phosphor is excited by the primary light 10, the near-infrared phosphor is excited by blue light with a relatively short wavelength, and therefore the near-infrared light-emitting device 100 is suitable for use in combination with visible phosphors of green, yellow, orange, and red, as needed.

[0052] The solid-state light-emitting element 1 is an element that converts electricity into light, and when powered and driven, converts the supplied electrical energy into light energy. The converted light energy is then emitted from the light extraction surface as primary light 10. Representative examples of the solid-state light-emitting element 1 include light-emitting diodes (LEDs) and laser diodes (LDs).

[0053] The wavelength converter 2 includes the above-mentioned near-infrared phosphor. The wavelength converter 2 may be, for example, a resin molded body in which particles of the near-infrared phosphor are dispersed in a resin, or may be a fluorescent ceramic in which powder of the near-infrared phosphor is compressed and sintered.

[0054] The wavelength converter 2 may contain fluorescent ceramics as a main component. Fluorescent ceramics not only improve the thermal conductivity of the wavelength converter 2 but also increase the optical absorptivity of the excitation light. Therefore, the use of fluorescent ceramics results in a near-infrared light emitting device 100 that is advantageous for heat dissipation design and high output, particularly for increasing the output of near-infrared light components. The wavelength converter 2 containing fluorescent ceramics as a main component means that the wavelength converter 2 contains 75% by weight or more of fluorescent ceramics. The wavelength converter 2 may also contain 90% by weight or more of fluorescent ceramics.

[0055] The fluorescent ceramic may contain a near-infrared phosphor as a main component. The term "fluorescent ceramic contains a near-infrared phosphor as a main component" means that the fluorescent ceramic contains 75% by weight or more of the near-infrared phosphor. The fluorescent ceramic may contain 90% by weight or more, or even 100% by weight, of the near-infrared phosphor. This not only provides excellent thermal conductivity but also increases the optical absorption rate of the excitation light. This is advantageous for heat dissipation design and high output, particularly for high output of the near-infrared light component.

[0056] The near-infrared phosphor is preferably excited by the primary light 10 emitted by the solid-state light-emitting element 1. In this way, the solid-state light-emitting element 1 is utilized, and the near-infrared phosphor is excited by the primary light 10 emitted by the solid-state light-emitting element 1, resulting in a near-infrared light-emitting device 100 that is advantageous for full solidification.

[0057] The near-infrared light emitting device 100 emits output light 20 including near-infrared light 21 emitted by a near-infrared phosphor, and the output light 20 may have a spectral intensity at least over the entire wavelength range of 800 nm to 1300 nm. The near-infrared light emitting device 100 emitting such output light 20 is suitable for spectroscopy detection or analysis of characteristic absorption bands of N-H, C-H, and O-H stretching vibrations, food quality evaluation of fresh fish and meat, and resin component analysis for plastic sorting. The output light 20 may have a spectral intensity at least over the entire wavelength range of 700 nm to 1000 nm. The near-infrared light emitting device 100 emitting such output light 20 is suitable for spectroscopy detection or analysis of characteristic absorption bands of N-H, C-H, and O-H stretching vibrations. The output light 20 may also have a spectral intensity at least over the entire wavelength range of 1100 nm to 1400 nm. Such a spectral distribution is suitable for evaluating the quality of food such as fresh fish and meat, as well as for analyzing resin components for the purpose of sorting plastics.

[0058] The near-infrared light-emitting device 100 emits output light 20 containing near-infrared light 21 emitted by a near-infrared phosphor. The output light 20 may have a spectral peak in the wavelength range of 800 nm to 1600 nm, particularly 800 nm to 860 nm. Such output light 20 has a spectral peak in the near-infrared wavelength range similar to that of a halogen bulb. This makes it relatively easy to use the components and accompanying software of conventional spectroscopic devices that use halogen bulbs. Therefore, spectroscopic devices can be industrially produced without major design changes. Furthermore, it has recently been discovered that simply irradiating harvested fruits and vegetables with near-infrared light at a wavelength around 850 nm for a very short period of time can prevent subsequent loss of freshness and spoilage, and improve fruit quality by maintaining vitamin C, inhibiting softening, and maintaining luster. Therefore, the near-infrared light-emitting device 100 of this embodiment is advantageous for preserving the freshness of such fruits and vegetables.

[0059] As shown in FIG. 2 , the near-infrared light emitting device 100 may further include a visible phosphor that emits visible fluorescence 22. Such a near-infrared light emitting device 100 can emit output light 20 that includes the visible fluorescence 22. The visible fluorescence 22 may have a maximum fluorescence intensity within the wavelength range of visible light. For example, the visible fluorescence 22 may have a maximum fluorescence intensity within a wavelength range of 490 nm or more and less than 780 nm. The visible phosphor may be contained in the same wavelength converter as the near-infrared phosphor. Alternatively, the visible phosphor may be contained in a wavelength converter different from the near-infrared phosphor. For example, the near-infrared light emitting device 100 may include a first wavelength converter and a second wavelength converter, where the first wavelength converter includes a visible phosphor and the second wavelength converter includes a near-infrared phosphor.

[0060] The visible phosphor may be excited by the primary light 10 emitted by the solid-state light emitting element 1. When the visible phosphor is excited by the primary light 10 emitted by the solid-state light emitting element 1, the near-infrared light emitting device 100 is advantageous for being fully solid-state and being compact. The primary light 10 is preferably blue light having a maximum intensity within a blue wavelength range of 435 nm or more and less than 480 nm.

[0061] It is preferable that the near-infrared phosphor and the visible phosphor are excited by only one type of solid-state light-emitting element 1. This is advantageous in terms of simplifying the lighting circuit. It is more preferable to excite these phosphors with blue light, which has a relatively short wavelength, because this increases the options for visible phosphors and makes it possible to adjust the light from green to yellow to orange to red.

[0062] The visible phosphor may be at least one phosphor selected from the group consisting of a green phosphor emitting light having a maximum fluorescence intensity within a wavelength range of 490 nm or more and less than 570 nm, a yellow phosphor emitting light having a maximum fluorescence intensity within a wavelength range of 570 nm or more and less than 585 nm, an orange phosphor emitting light having a maximum fluorescence intensity within a wavelength range of 585 nm or more and less than 620 nm, and a red phosphor emitting light having a maximum fluorescence intensity within a wavelength range of 620 nm or more and less than 780 nm. This allows the spectral distribution of the visible fluorescent component to be adjusted. Therefore, the visible fluorescent component of the output light 20 emitted from the near-infrared light-emitting device 100 can be adjusted according to the application.

[0063] The visible phosphor is Ce ３＋ Garnet phosphor activated with Eu ２＋ Alkaline earth metal nitrosilicate activated with Eu ２＋ The visible light emitting device 100 may include at least one phosphor selected from the group consisting of alkaline earth metal nitride aluminosilicates activated with an alkali metal nitrate. These visible light emitting phosphors have a proven track record of practical use in LED lighting. Therefore, the near-infrared light emitting device 100 includes these visible light emitting phosphors that are not only easy to procure but also safe in terms of reliability and handling.

[0064] Ce ３＋ Examples of the garnet phosphor activated by the general formula RE ３ Al ２ (AlO ４ ) ３ : Ce ３＋ a phosphor represented by the formula: Ca ３ Sc ２ (SiO ４ ) ３ : Ce ３＋ , Y ３ Ga ２ (AlO ４ ) ３ : Ce ３＋ In the above general formula, RE represents a rare earth element, and is, for example, at least one element selected from the group consisting of Sc, Y, La, Tb, Gd, and Lu. ３ Al ２ (AlO ４ ) ３ : Ce ３＋ Specific examples of the phosphor represented by the formula include Lu ３ Al ２ (AlO ４ ) ３ : Ce ３＋ , Y ３ Al ２ (AlO ４ ) ３ : Ce ３＋ (YAG) and (Y,Gd) ３ Al ２ (AlO ４ ) ３ : Ce ３＋ Examples include:

[0065] EU ２＋ Examples of activated alkaline earth metal nitrosilicates include Sr ２ Si ５ N ８ :Eu ２＋ , Ca ２ Si ５ N ８ :Eu ２＋ and solid solutions thereof.

[0066] EU ２＋ Examples of activated alkaline earth metal nitride aluminosilicates include those represented by the general formula MAlSiN ３ :Eu ２＋ In the above general formula, M represents an alkaline earth metal, for example, at least one metal element selected from the group consisting of Mg, Ca, Sr, and Ba. Specifically, Eu ２＋ Examples of activated alkaline earth metal nitride aluminosilicates include CaAlSiN ３ :Eu ２＋ (CASN), SrAlSiN ３ :Eu ２＋ , (Sr,Ca)AlSiN ３ :Eu ２＋ (SCASN) and solid solutions thereof.

[0067] Among these, it is preferable that the visible phosphor contains at least one phosphor selected from the group consisting of YAG, CASN, and SCASN.

[0068] The near-infrared light-emitting device 100 according to this embodiment can be widely used in non-destructive testing using spectroscopy, particularly in quality evaluation of fruits and vegetables, as well as quality evaluation of fresh fish, meat, and processed foods. For example, oleic acid, which contributes to the quality of Wagyu beef, has an absorption peak around 930 nm, so by using this wavelength, the distribution of oleic acid contained in Wagyu beef can be visualized. Furthermore, lipids contained in tuna also have an absorption peak around 930 nm, so by using this wavelength, the lipid content of the tuna can be measured. Furthermore, the near-infrared light-emitting device 100 can also be used to measure the moisture content of food.

[0069] As described above, the near-infrared light emitting device 100 according to this embodiment includes the near-infrared phosphor described above. Therefore, the near-infrared light emitting device 100 can be widely used as a light source for spectroscopic devices that utilize spectroscopy.

[0070] [Spectroscopic Device] Next, a spectroscopic device 200 according to this embodiment will be described with reference to Figs. 3 and 4. The spectroscopic device 200 is, for example, a near-infrared spectroscopic device. Fig. 3 schematically shows an example of a transmission-type spectroscopic device 200. Fig. 4 schematically shows an example of a reflection-type spectroscopic device 200. As shown in Figs. 3 and 4, the spectroscopic device 200 includes a near-infrared light-emitting device 100.

[0071] As shown in FIG. 3 , the transmission type spectrometer 200 includes a near-infrared light emitting device 100 and a spectroscope 6. An inspection object 5 is disposed between the near-infrared light emitting device 100 and the spectroscope 6. The near-infrared light emitting device 100 is configured to emit output light 20. The inspection object 5 is disposed so as to be irradiated with the output light 20. The spectroscope 6 is disposed so as to receive transmitted light 11, particularly near-infrared transmitted light, that has passed through the interior of the inspection object 5 out of the output light 20 irradiated onto the inspection object 5. The spectroscope 6 detects and separates the transmitted light 11. The spectroscope 6 is a near-infrared spectroscope, and a spectrometer equipped with a Si-based sensor can be used.

[0072] The spectroscopic device 200 may be an inspection device. The inspection device may analyze data obtained by spectroscopy using the spectrometer 6. The inspection device may include an analysis unit (not shown), which may grasp or determine pass / fail of inspection items such as the internal state and quality of the inspection object 5. The analysis unit may include a central processing unit (CPU), a read-only memory (ROM), and a random access memory (RAM). The CPU may read a program and reference data stored in the ROM and process information related to the analysis of the inspection items according to the program.

[0073] 4, the reflective spectroscopic device 200 also includes a near-infrared light emitting device 100 and a spectroscope 6. However, in the reflective spectroscopic device 200, the spectroscope 6 is arranged to receive reflected light 12, particularly near-infrared reflected light, reflected by the inspection object 5 out of the output light 20 irradiated onto the inspection object 5. Other than the above, the reflective spectroscopic device 200 is the same as the transmission spectroscopic device 200, and therefore a description thereof will be omitted.

[0074] The reflection-type spectroscopic device 200 may include a reflective member (not shown), such as a metal plate, in particular a near-infrared reflective member. If the near-infrared light component of the output light 20 that has passed through the inspection object 5 is reflected by the reflective member and passes through the interior of the inspection object 5 again, it is possible to easily obtain near-infrared spectroscopic data specific to the inspection object 5, even if the inspection object 5 is a liquid or the like.

[0075] It is sufficient that the transmitted light 11 and the reflected light 12 contain at least a near-infrared light component. The light source 10 may transmit or reflect visible fluorescent components depending on the form of the inspection object 5. When the light source 10 reflects visible light components, the visible light components may be separated into spectral components, or the light source 10 may be used for visual inspection of the inspection object 5.

[0076] The inspection target object 5 may be food. Note that "food" is a general term for items consumed by humans, such as ingredients for lunch boxes, grains, fruits and vegetables, meat, fish, processed foods, and beverages.

[0077] The spectroscopic device 200 can also be used as a foreign matter inspection device that inspects whether or not the inspection target 5 contains foreign matter. For example, the spectroscopic device 200 can be used to detect the presence and condition of foreign matter mixed into food. The spectroscopic device 200 can also be used as an inspection device other than a foreign matter inspection device, such as a quality control device that evaluates the quality of fruits and vegetables. Such a spectroscopic device 200 is suitable for quality control of fruits and vegetables, because it can evaluate or measure the sugar content, acidity, internal damage, etc. of fruits and vegetables by examining the amount of transmission of near-infrared light irradiated onto the fruits and vegetables.

[0078] In this way, the spectroscopic device 200 utilizes at least the near-infrared light component contained in the output light 20. The spectroscopic device 200 may detect, for example, a characteristic absorption band of at least one stretching vibration selected from the group consisting of N-H, C-H, and O-H. In other words, the spectroscopic device 200 may be configured to obtain near-infrared spectroscopic data such as these characteristic absorption bands. Because the characteristic absorption band is detected as analytical data, the spectroscopic device 200 can be used in a wide range of applications, and is highly versatile, which is preferable.

[0079] As described above, the spectroscopic device 200 includes the near-infrared light emitting device 100 that outputs the output light 20 having a near-infrared light component. Therefore, the spectroscopic device 200 of this embodiment can be widely used for foreign substance inspection, quality inspection, and the like.

[0080] [Sensing Device] Next, a sensing device according to this embodiment will be described. In recent years, there has been an increasing demand for non-contact vital sign sensing, and the near-infrared light emitting device according to this embodiment can be used in a sensing device for non-contact vital sign sensing.

[0081] Non-contact vital sensing involves, for example, using a light emitting device to irradiate a subject with visible light, near-infrared light, or the like, and capturing an image of the subject's imaging area with a camera to obtain image data, which is then processed by a computer to obtain vital information. ２These include oxygen saturation (measured by a pulse oximeter), blood pressure, pulse wave, and information on blood vessels deep within the body. A device including a light-emitting device, a camera, and a computer used for non-contact vital sensing is also generally referred to as a sensing device.

[0082] The vital information obtained by non-contact vital sensing varies depending on the emission spectrum of the output light of the light-emitting device. For example, to obtain blood pressure information, output light with a high intensity of the light component at a wavelength of 850 nm is preferable. To obtain pulse wave information, output light with a high intensity of the light component at a wavelength of 940 nm is preferable. Thus, in non-contact vital sensing, it is preferable to obtain output light with a high intensity of the light component in the near-infrared region.

[0083] The near-infrared light emitting device of this embodiment can emit near-infrared light with a fluorescence peak wavelength of 1000 nm or less with high efficiency, and therefore can be suitably used in such sensing devices.

[0084] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0085] (Technology 1) MgGa ２ O ４ A near-infrared phosphor having the same spinel-type crystal structure as that of the compound represented by general formula (1) and having Cr ions added thereto. ｘｐ MB （２－２ｘ＋２ｙ）ｑ MC （４＋ｘ－４ｙ）ｒｑ MD ２ｙｓ O ８ ... (1) (In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements, MB is one or more elements selected from Group 2 elements and Group 12 elements, MC is one or more elements selected from Group 3 elements and Group 13 elements, MD is one or more elements selected from Group 4 elements and Group 14 elements, and p, q, r, s, x, and y satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦x≦0.99, 0≦y≦0.99, 0.01≦x+y≦0.99.)

[0086] With this configuration, the near-infrared phosphor has excellent fluorescent properties, so that a highly efficient near-infrared light emitting device can be obtained.

[0087] (Technology 2) The near-infrared phosphor according to Technology 1, wherein the near-infrared phosphor emits fluorescence when irradiated with excitation light having a wavelength of 450 nm, the spectral distribution of the fluorescence has a maximum fluorescence intensity within a wavelength range of 800 nm or more and 1600 nm or less, and the half-width of the spectrum having the maximum fluorescence intensity exceeds 100 nm.

[0088] This configuration allows for highly efficient excitation of the near-infrared phosphor, resulting in a highly efficient near-infrared light-emitting device. The near-infrared light-emitting device can also be used for determining the moisture content of food, evaluating the quality of fresh fish and meat, and analyzing resin components for the purpose of sorting plastics.

[0089] (Technology 3) A near-infrared phosphor according to Technology 1 or 2, wherein in general formula (1), MA is an alkali metal element, and MB is at least one of an alkaline earth metal element and zinc.

[0090] With this configuration, the near-infrared phosphor has excellent fluorescent properties, so that a highly efficient near-infrared light emitting device can be obtained.

[0091] (Technology 4) A near-infrared phosphor according to any one of Technologies 1 to 3, wherein the general formula (1) satisfies at least one of the following (1) to (4): (1) MA is at least one selected from the group consisting of Li, Na, and K; (2) MB is at least one selected from the group consisting of Mg and Zn; (3) MC is at least one selected from the group consisting of Ga, B, and Al; (4) MD is Ge.

[0092] With this configuration, the near-infrared phosphor has excellent fluorescent properties, so that a highly efficient near-infrared light emitting device can be obtained.

[0093] (Technology 5) A near-infrared phosphor according to any one of technologies 1 to 4, wherein in general formula (1), MA is at least one selected from the group consisting of Li, Na, and K, MB is at least one selected from the group consisting of Mg and Zn, MC is at least one selected from the group consisting of Ga, B, and Al, and MD is Ge.

[0094] With this configuration, the near-infrared phosphor has excellent fluorescent properties, so that a highly efficient near-infrared light emitting device can be obtained.

[0095] (Technology 6) The near-infrared phosphor according to any one of Technologies 1 to 5, wherein Cr ions and Ni ions are added to the inorganic compound.

[0096] By coactivating Cr ions and Ni ions in an inorganic compound, a near-infrared phosphor having a maximum fluorescence intensity at wavelengths of 1200 nm or more can be obtained.

[0097] (Technology 7) The near-infrared phosphor according to any one of Technologies 1 to 6, which is a powder phosphor or a fluorescent ceramic.

[0098] Since the near-infrared phosphor is a powder phosphor, it can be easily produced by simply mixing it with a transparent resin and curing it. Furthermore, since the near-infrared phosphor is a fluorescent ceramic, it is possible to produce a wavelength converter that not only has excellent thermal conductivity but also has a high optical absorption rate of excitation light.

[0099] (Technology 8) A near-infrared light emitting device comprising the near-infrared phosphor according to any one of technologies 1 to 7.

[0100] With this configuration, it is possible to obtain a near-infrared light emitting device that outputs high-power near-infrared light components suitable for near-infrared spectroscopy.

[0101] (Technology 9) The near-infrared light emitting device according to Technology 8, further comprising a solid-state light emitting element, wherein the near-infrared phosphor is excited by excitation light emitted by the solid-state light emitting element.

[0102] This configuration makes it possible to obtain a near-infrared light emitting device that outputs high-power near-infrared light components suitable for near-infrared spectroscopy. In addition, by utilizing a solid-state light emitting element and using the primary light emitted by it to excite a near-infrared phosphor, the near-infrared light emitting device is advantageous for full solidification.

[0103] (Technology 10) A spectroscopic device comprising the near-infrared light emitting device according to Technology 8 or 9.

[0104] This spectrometer utilizes a near-infrared light emitting device that outputs near-infrared light having a spectral distribution over a wide wavelength range, and is therefore advantageous in terms of application to a variety of uses.

[0105] (Technology 11) A sensing device comprising the near-infrared light emitting device according to Technology 8 or 9.

[0106] This sensing device is equipped with a near-infrared light emitting device that emits near-infrared light with high efficiency, and therefore can be suitably used for non-contact vital sign sensing.

[0107] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

[0108] When synthesizing the phosphors of each example, the following compound powders were used as raw materials: Lithium carbonate (Li ２ CO ３ ): Purity 2N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Magnesium oxide (MgO): Purity 3N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Gallium oxide (Ga ２ O ３ ): Purity 4N, manufactured by Asia Physical Materials Co., Ltd. Chromium oxide (Cr ２ O ３ Zinc oxide (ZnO): Purity 2N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Germanium oxide (GeO ２ ): Purity 3N, manufactured by High Purity Chemical Laboratory Co., Ltd. Aluminum oxide (Al ２ O ３ ): Purity 3N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sodium carbonate (Na ２ CO ３ ): Purity 2N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Potassium carbonate (K ２ CO ３ ): Purity 2N5, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Nickel oxide (NiO): Purity 3N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Boric acid (H ３ BO ３ ): Purity 2N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0109] (Example 1-1) The oxide phosphor of this example was synthesized by a preparation method using a solid-state reaction. ２ Ga ９ O １６ An oxide phosphor was synthesized, which is represented by the composition formula: Cr: 4% In the oxide phosphor, the chromium concentration is the amount of chromium substance in the amount of metal element substance.

[0110] First, the stoichiometric compound LiMg ２ Ga ９ O １６ The raw materials were weighed so that the Cr content was 4%. Then, the raw materials were dry-mixed using a mortar and pestle to prepare a firing raw material.

[0111] Next, the firing raw materials were transferred to a lidded alumina crucible and fired in a box-type electric furnace in an air atmosphere at 1400°C for 4 hours, after which the fired product was lightly crushed. Thus, the phosphor of this example was obtained. The phosphor composition, the x and y values ​​when the phosphor is expressed by general formula (1), and the firing temperature are summarized in Table 2.

[0112] (Examples 1-2 to 1-3, Comparative Examples 1-4 to 1-5, Examples 1-6 to 1-9) The phosphors of each example were obtained by the same method as in Example 1-1, except that the raw materials were weighed so as to obtain the phosphor compositions shown in Table 2. The phosphor of Comparative Example 1-4 corresponds to the phosphor of Patent Document 1, and the phosphor of Comparative Example 1-5 corresponds to the phosphor of Patent Document 2.

[0113] (Examples 2-1 to 2-3) The raw materials were weighed so as to obtain the phosphor compositions shown in Table 3, and phosphors of each example were obtained by the same method as in Example 1-1, except that the firing temperature was changed to 1600°C. The phosphor of Example 2-1 is a phosphor in which the firing temperature is higher than that of Example 1-1. The phosphor of Example 2-2 is a phosphor in which the firing temperature is higher than that of Example 1-1 and the x value is further reduced. The phosphor of Example 2-3 is a phosphor in which the firing temperature is higher than that of Example 1-1 and the x value is further increased.

[0114] (Example 3-1, Comparative Example 3-2) Phosphors of each example were obtained by the same method as in Example 1-1, except that the raw materials were weighed so as to obtain the phosphor composition shown in Table 3. The phosphor of Example 3-1 is a phosphor obtained by substituting zinc (Zn) for magnesium (Mg) in the phosphor of Example 1-1. The phosphor of Comparative Example 3-2 is a phosphor obtained by substituting zinc (Zn) for magnesium (Mg) in the phosphor of Comparative Example 1-4.

[0115] Example 4-1, Comparative Examples 4-2 to 4-3, Example 4-4 The phosphors of each example were obtained in the same manner as in Example 1-1, except that the raw materials were weighed so as to obtain the phosphor compositions shown in Table 3.

[0116] (Examples 5-1 to 5-2) The above raw materials were weighed to obtain the phosphor compositions shown in Table 4, and phosphors of each example were obtained by the same method as in Example 1-1, except that the firing temperature was changed to 1600°C. The phosphor of Example 5-1 is the same as the phosphor of Example 2-1. The phosphor of Example 5-2 is a phosphor obtained by reducing the amount of chromium activation in the phosphor of Example 5-1 to 2 mol%.

[0117] (Examples 6-1 to 6-3) The above raw materials were weighed so as to obtain the phosphor composition shown in Table 4, and phosphors of each example were obtained by the same method as in Example 1-1, except that the firing temperature was changed to 1600°C. The phosphor of Example 6-1 is the same phosphor as the phosphor of Example 2-1. The phosphor of Example 6-2 is a phosphor in which all of the gallium (Ga) in the phosphor of Example 2-1 has been substituted with aluminum (Al). The phosphor of Example 6-3 is a phosphor in which part of the gallium (Ga) in the phosphor of Example 2-1 has been substituted with aluminum (Al).

[0118] (Examples 7-1 to 7-3, Comparative Examples 7-4 to 7-5, Example 7-6) The phosphors of each example were obtained by the same method as in Example 1-1, except that the raw materials were weighed so as to obtain the phosphor composition shown in Table 4. The phosphor of Example 7-1 is the same phosphor as that of Example 1-1. Example 7-2 is a phosphor in which part of the lithium (Li) in the phosphor of Example 7-1 is substituted with sodium (Na). Example 7-3 is a phosphor in which all of the lithium (Li) in the phosphor of Example 7-1 is substituted with sodium (Na). Comparative Example 7-4 is a phosphor in which part of the lithium (Li) in the phosphor of Comparative Example 1-5 is substituted with sodium (Na). Comparative Example 7-5 is a phosphor in which all of the lithium (Li) in the phosphor of Comparative Example 1-5 is substituted with sodium (Na). Example 7-6 is a phosphor in which all of the lithium (Li) in the phosphor of Example 7-1 is substituted with potassium (K).

[0119] (Examples 8-1 to 8-7) The above raw materials were weighed to obtain the phosphor compositions shown in Table 5, and phosphors of each example were obtained by the same method as in Example 1-1, except that the firing temperature was changed to 1600°C. The phosphor of Example 8-1 is the same as the phosphor of Example 2-1. The phosphor of Example 8-2 is a phosphor obtained by adding 1 mol% of nickel (Ni) as an activator to the phosphor of Example 8-1. The phosphor of Example 8-3 is a phosphor obtained by substituting aluminum (Al) for some of the gallium (Ga) in the phosphor of Example 8-2. The phosphor of Example 8-4 is a phosphor obtained by substituting zinc (Zn) for all of the magnesium (Mg) in the phosphor of Example 8-2. The phosphor of Example 8-5 is a phosphor obtained by substituting sodium (Na) for all of the lithium (Li) in the phosphor of Example 8-2. The phosphor of Example 8-6 is a phosphor obtained by substituting all of the lithium (Li) in the phosphor of Example 8-2 with potassium (K). The phosphor of Example 8-7 is a phosphor obtained by substituting some of the lithium (Li) in the phosphor of Example 8-2 with potassium (K).

[0120] (Examples 9-1 to 9-3) Phosphors of each example were obtained by the same method as in Example 1-1, except that the raw materials were weighed so as to obtain the phosphor composition shown in Table 4. The phosphor of Example 9-1 is the same as the phosphor of Example 1-1. The phosphors of Examples 9-2 and 9-3 are phosphors in which part of the gallium (Ga) in the phosphor of Example 9-1 has been substituted with boron (B).

[0121]

[0122]

[0123]

[0124]

[0125] [Evaluation] Next, the crystal structure and fluorescent properties of the compounds constituting the phosphor were evaluated for the synthesized phosphor samples.

[0126] (Crystal Structure Analysis) For the phosphors of Examples 1-1 to 1-3 and Comparative Examples 1-4 to 1-5, X-ray diffraction patterns were measured by X-ray diffraction using a desktop X-ray diffractometer MiniFlex600 (Rigaku Corporation). Then, the crystalline phases of the compounds constituting the phosphors were identified by comparing the diffraction patterns with the diffraction patterns of the compound crystals whose data had been registered.

[0127] As shown in FIG. 5, the phosphors of Examples 1-1 to 1-3 and Comparative Examples 1-4 to 1-5 are MgGa ２ O ４ Therefore, these phosphors show the same diffraction patterns as MgGa ２ O ４ It can be seen that the phosphors of Examples 1-1 to 1-3 have the same crystal structure as that of MgGa. Also, it can be seen from FIG. 5 that the diffraction lines shift to the higher angle side as the x value increases. ２ O ４ and LiGa ５ O ８ It is presumed that all of the elements are in solid solution.

[0128] Therefore, the phosphors of Examples 1-1 to 1-3 are made of the compound MgGa ２ O４ It has the same spinel-type crystal structure as MgGa ２ O ４ and LiGa ５ O ８ It can be seen that the phosphor of Example 1-1 is a Cr-activated phosphor having a solid solution of MgGa as the host crystal. ２ O ４ and LiGa ５ O ８ It can also be seen that the Cr-activated phosphor has a host crystal with an intermediate composition between MgGa and ２ O ４ and LiGa ５ O ８ Since the diffraction patterns of these compounds are similar, they are compounds with the same crystal structure.

[0129] 6, it can be seen that the phosphor of Example 1-1 and the phosphor of Example 4-1 also show similar diffraction patterns. Therefore, even if some of the constituent elements of the phosphor of Example 1-1 are replaced with germanium, MgGa ２ O ４ It is found that it has the same crystal structure as

[0130] (Fluorescence Properties) Using a Quantaurus-QY Plus (extended absolute PL quantum yield measurement system with heating mechanism) C13534-02 (manufactured by Hamamatsu Photonics K.K.), the fluorescence properties of the phosphors were measured when excited at an excitation wavelength of 450 nm. The measured fluorescence properties were the internal quantum efficiency (IQE) and external quantum efficiency (EQE) at wavelengths of 600 nm to 1600 nm, the fluorescence spectrum, the wavelength of the maximum fluorescence intensity (fluorescence peak wavelength), and the full width at half maximum (FWHM) of the spectrum having the maximum fluorescence intensity. The results of the measured fluorescence properties are summarized in Tables 2 and 3.

[0131] As shown in Table 2, it can be seen that the fluorescence peak wavelengths of the phosphors of Examples 1-1 to 1-3 are between the fluorescence peak wavelength of the phosphor of Comparative Example 1-4, which corresponds to Patent Document 1, and the fluorescence peak wavelength of the phosphor of Comparative Example 1-5, which corresponds to Patent Document 2. However, it can be seen that the phosphors of Examples 1-1 to 1-3 have improved internal quantum efficiency and external quantum efficiency compared to the phosphors of Comparative Examples 1-4 and 1-5.

[0132] Thus, the fluorescence peak wavelength of the phosphor of Example 1-1 is an intermediate value between the fluorescence peak wavelengths of the phosphors of Comparative Examples 1-4 and 1-5. However, the fluorescence characteristics of the phosphor of Example 1-1 are not simply an intermediate value between the fluorescence characteristics of the phosphors of Comparative Examples 1-4 and 1-5, but are surprisingly improved over these phosphors. Furthermore, as shown in FIG. 7, the fluorescence intensity of the phosphor of Example 1-1 is also improved compared to the phosphors of Comparative Examples 1-4 and 1-5.

[0133] Furthermore, comparing Example 1-6 with Comparative Example 1-4, it can be seen that the internal quantum efficiency and external quantum efficiency are improved by setting the x value between 0 and 0.01. Similarly, comparing Example 1-9 with Comparative Example 1-5, it can be seen that the internal quantum efficiency and external quantum efficiency are improved by setting the x value between 1 and 0.99. Therefore, it can be seen from Examples 1-1 to 1-3 and 1-6 to 1-9 that the fluorescent properties of the resulting phosphor are improved by setting the x value between 0.01 and 0.99.

[0134] Furthermore, it is clear that the phosphors of Examples 1-1 to 1-3 and Examples 1-6 to 1-9 have a half-value width exceeding 200 nm.

[0135] Furthermore, it can be seen from Examples 1-1 and 2-1, Examples 1-2 and 2-2, and Examples 1-3 and 2-3 that the fluorescent properties can be improved by increasing the firing temperature when preparing the phosphor.

[0136] From Example 3-1 and Comparative Example 3-2 shown in Table 3, it can be seen that even when magnesium in the phosphor of Example 1-1 is replaced with zinc, the fluorescent properties are still good.

[0137] Furthermore, from Examples 4-1 and 4-4 and Comparative Examples 4-2 and 4-3 shown in Table 3, it can be seen that even if some of the constituent elements of the phosphor of Example 1-1 are replaced with germanium, the fluorescent properties are improved.

[0138] From Examples 5-1 and 5-2 shown in Table 4, it can be seen that even if the concentration of chromium ions activated in the phosphor of Example 2-1 is reduced, the fluorescent properties are still good.

[0139] Furthermore, from Examples 6-1 to 6-3 shown in Table 4, it can be seen that even when gallium in the phosphor of Example 2-1 is replaced with aluminum, the fluorescent properties are still good.

[0140] From Examples 7-1 to 7-3, Comparative Examples 7-4 and 7-5, and Example 7-6 shown in Table 4, it can be seen that even when lithium in the phosphor of Example 1-1 is replaced with sodium and potassium, the fluorescent properties are good.

[0141] Specifically, in the phosphor of Example 7-2, half of the lithium in the phosphor of Example 1-1 is substituted with sodium, and in the phosphor of Comparative Example 7-4, half of the lithium in the phosphor of Comparative Example 1-5 is substituted with sodium. Example 7-2 and Comparative Example 7-4 show that the phosphor of this embodiment has good fluorescent properties even when lithium is substituted with sodium. Furthermore, in the phosphor of Example 7-3, all of the lithium in the phosphor of Example 1-1 is substituted with sodium, and in the phosphor of Comparative Example 7-5, all of the lithium in the phosphor of Comparative Example 1-5 is substituted with sodium. Example 7-3 and Comparative Example 7-5 show that the phosphor of this embodiment has good fluorescent properties even when lithium is substituted with sodium.

[0142] Furthermore, Examples 8-1 to 8-7 shown in Table 5 demonstrate that adding chromium ions and nickel ions as activators results in near-infrared phosphors with maximum fluorescence intensity at wavelengths of 1100 nm or greater. Furthermore, Figure 8 shows the emission spectra of the phosphors of Examples 1-1 and 8-2 when excited at a wavelength of 450 nm. Figure 8 demonstrates that adding chromium ions and nickel ions as activators reduces the intensity of the fluorescence derived from chromium ions, while increasing the fluorescence derived from nickel ions. Furthermore, the fluorescence derived from nickel ions has a broad spectrum with a fluorescence peak near 1270 nm. Therefore, by adding nickel ions to a near-infrared phosphor, the nickel ions absorb the fluorescence emitted by the chromium ions, thereby emitting near-infrared light at a longer wavelength and over a broader band.

[0143] From Examples 9-1 to 9-3 shown in Table 5, it can be seen that the fluorescent properties are improved even when gallium in the phosphor of Example 1-1 is substituted with boron. It can also be seen that the emission peak wavelength shifts to the longer wavelength side as the ratio of gallium to boron is increased.

[0144] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0145] The entire contents of Japanese Patent Application No. 2024-027150 (filing date: February 27, 2024) are incorporated herein by reference.

[0146] According to the present disclosure, it is possible to provide a near-infrared phosphor having excellent fluorescence properties, a near-infrared light emitting device including the near-infrared phosphor, and a spectroscopic device and a sensing device including the near-infrared light emitting device.

[0147] 1 Solid-state light-emitting element 100 Near-infrared light-emitting device 200 Spectroscopic device

Claims

1. MgGa ２ O ４ A near-infrared phosphor having the same spinel-type crystal structure as that of the compound represented by general formula (1) and having Cr ions added thereto. ｘｐ MB （２－２ｘ＋２ｙ）ｑ MC （４＋ｘ－４ｙ）ｒｑ MD ２ｙｓ O ８ ... (1) (In the formula, MA is one or more elements selected from Group 1 elements and Group 11 elements, MB is one or more elements selected from Group 2 elements and Group 12 elements, MC is one or more elements selected from Group 3 elements and Group 13 elements, MD is one or more elements selected from Group 4 elements and Group 14 elements, and p, q, r, s, x, and y satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦x≦0.99, 0≦y≦0.99, 0.01≦x+y≦0.99.) 2. The near-infrared phosphor according to claim 1, wherein the near-infrared phosphor emits fluorescence when irradiated with excitation light having a wavelength of 450 nm, the spectral distribution of the fluorescence has a maximum fluorescence intensity within a wavelength range of 800 nm to 1600 nm, and the half-width of the spectrum having the maximum fluorescence intensity exceeds 100 nm.

3. The near-infrared phosphor according to claim 1 or 2, wherein in general formula (1), MA is an alkali metal element, and MB is at least one of an alkaline earth metal element and zinc.

4. A near-infrared phosphor according to any one of claims 1 to 3, wherein general formula (1) satisfies at least one of the following (1) to (4): (1) MA is at least one selected from the group consisting of Li, Na, and K; (2) MB is at least one selected from the group consisting of Mg and Zn; (3) MC is at least one selected from the group consisting of Ga, B, and Al; (4) MD is Ge.

5. The near-infrared phosphor according to any one of claims 1 to 4, wherein in general formula (1), MA is at least one selected from the group consisting of Li, Na, and K, MB is at least one selected from the group consisting of Mg and Zn, MC is at least one selected from the group consisting of Ga, B, and Al, and MD is Ge.

6. A near-infrared phosphor according to any one of claims 1 to 5, wherein Cr ions and Ni ions are added to the inorganic compound.

7. The near-infrared phosphor according to any one of claims 1 to 6, which is a powdered phosphor or a fluorescent ceramic.

8. A near-infrared light emitting device comprising the near-infrared phosphor according to any one of claims 1 to 7.

9. The near-infrared light emitting device according to claim 8, further comprising a solid-state light emitting element, wherein the near-infrared phosphor is excited by excitation light emitted by the solid-state light emitting element.

10. A spectroscopic device comprising the near-infrared light emitting device according to claim 8 or 9.

11. A sensing device comprising the near-infrared light emitting device according to claim 8 or 9.

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