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

Abstract

This near-infrared phosphor has the same orthorhombic crystal structure as Mg2GeO4, and is formed by adding Cr ions to an inorganic compound represented by general formula (1).　Formula (1): (MApMCq)z(MB2r)1-z(MD)sO4, wherein MA is at least one element selected from Group-1 elements and Group-11 elements, MB is at least one element selected from Group-2 elements and Group-12 elements, MC is at least one element selected from Group-3 elements and Group-13 elements, MD is at least one element selected from Group-4 elements and Group-14 elements, and the following formulae are satisfied: 0.8 ≤ p ≤ 1.2, 0.8 ≤ q ≤ 1.2, 0.8 ≤ r ≤ 1.2, 0.8 ≤ s ≤ 1.2, and 0.01 ≤ z ≤ 0.49. This near-infrared light-emitting device is provided with the near-infrared phosphor, and this spectroscopic device and this sensing device are each provided with 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 near-infrared phosphors that are excited by excitation light emitted by the solid-state light emitting element and emit near-infrared light. Patent Document 1 describes a near-infrared light emitting material that is excited by blue light and red light. This near-infrared light emitting material has the chemical formula: LiMg ２ M １－ｘ Ge ２ O ８ : x% Cr ３＋ where 0.01≦x≦20 is satisfied, and M is one or both of Sc and In. The near-infrared luminescent material has excitation peaks at wavelengths of 250 to 360 nm, 360 to 560 nm, and 560 to 900 nm, an emission wavelength range of 850 to 1400 nm, and an emission half-width of about 300 nm. Furthermore, in Example 1 of Patent Document 1, a compound having the chemical formula: LiMg ２ Sc ０．９６ Cr ０．０４ Ge ２ O ８ The phosphor has an emission peak at around 1030 nm. Note that the fluorescence peaks of the phosphors shown in the examples of Patent Document 1 all exceed 1000 nm.

[0004] Chinese Patent Application Publication No. 112322290

[0005] A spectroscopic device using near-infrared light includes a near-infrared light emitting device that emits near-infrared light as described above, and a sensor (detector) that detects near-infrared light that has passed through an object to be inspected or that has been reflected by the object to be inspected. Such sensors include Si-based sensors and InGaAs-based sensors. Si-based sensors can detect near-infrared light with wavelengths of 1000 nm or less with high sensitivity, while InGaAs-based sensors can detect near-infrared light with wavelengths exceeding 1000 nm with high sensitivity.

[0006] However, InGaAs-based sensors are more expensive than Si-based sensors, and the maximum wavelength that Si-based sensors can measure is approximately 1000 nm. Therefore, when using a relatively inexpensive Si-based sensor, it is necessary to set the peak wavelength of the fluorescence emitted from the near-infrared phosphor to 1000 nm or less.

[0007] Furthermore, the present inventors have prepared the near-infrared light-emitting material of Patent Document 1 and evaluated its fluorescent properties, and as a result have found that the near-infrared light-emitting material does not have sufficient fluorescent properties. Therefore, there is a demand for a near-infrared phosphor with excellent fluorescent properties.

[0008] The present disclosure has been made in consideration of the problems inherent in the conventional technology. An object of the present disclosure is to provide a near-infrared phosphor that emits fluorescence that can be detected with high sensitivity even by a Si-based sensor and has excellent fluorescent properties, and a near-infrared light-emitting device that includes the near-infrared phosphor. Another object of the present disclosure is to provide a spectroscopic device and a sensing device that include the near-infrared light-emitting device.

[0009] In order to solve the above problems, the near-infrared phosphor according to the embodiment of the present disclosure contains Mg ２ GeO ４ It has the same orthorhombic crystal structure as that of the inorganic compound represented by the general formula (1), and is a phosphor obtained by adding Cr ions to the inorganic compound. ｐ MC ｑ ) ｚ (MB ２ｒ ) １－ｚ (MD) ｓ O ４... (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, and z satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, and 0.01≦z≦0.49.)

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

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

[0012] A sensing device according to an aspect of the present disclosure includes the near-infrared light emitting device described above.

[0013] 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 Example 1-1 and Comparative Examples 1-2 to 1-5, as well as the X-ray diffraction spectra of Mg ２ GeO ４ and LiScGeO ４ 6 is a graph showing the emission spectra of the phosphors of Example 1-1 and Comparative Examples 1-2, 1-3, and 1-5 when excited at a wavelength of 450 nm.

[0014] 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.

[0015] As described above, in Patent Document 1, LiMg ２ M １－ｘ Ge ２ O ８ : x% Cr ３＋Specifically, the present invention discloses a near-infrared emitting material represented by the formula: ２ Sc ０．９６ Cr ０．０４ Ge ２ O ８ Furthermore, Non-Patent Documents 1 and 2 disclose a phosphor that is a simple system of the near-infrared emitting material of Patent Document 1, Mg ２ GeO ４ : Cr phosphor and LiScGeO ４ [Non-Patent Document 1] Yongcheng Huo et al., “Enabling Yb 3+ Luminescence with Visible Light Response in Mg2GeO4 via Energy Transfer”, Inorg. Chem. 2023, 62, 35, 14402-14410 [Non-patent Document 2] Shihai Miao et al., “Broadband Short-Wave Infrared Light-Emitting Diodes Based on Cr 3+ -Doped LiScGeO4 Phosphor”, ACS Appl. Mater. Interfaces 2021, 13, 30, 36011-36019

[0016] Here, the present inventors have found that the phosphor of Patent Document 1, LiMg ２ ScGe ２ O ８ : 1% Cr, Mg, which is the phosphor of Non-Patent Document 1 ２ GeO ４ : 1% Cr, and LiScGeO, which is the phosphor of Non-Patent Document 2 ４ : 1% Cr was prepared and the fluorescent properties were evaluated. Furthermore, the concentration of Cr ions, which act as an activator, was standardized to 1 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 fluorescence peak wavelength, internal quantum efficiency (IQE), absorbance, and external quantum efficiency (EQE) of these phosphors were then measured.

[0017] As shown in Table 1, the phosphor of Patent Document 1 has a fluorescence peak wavelength of approximately 1000 nm, and when using a Si-based sensor, a further shortening of the wavelength is required. In contrast, the phosphor of Non-Patent Document 1 has a fluorescence peak wavelength of approximately 900 nm, and although it can be suitably used with a Si-based sensor, its internal quantum efficiency, absorbance, and external quantum efficiency are worse than those of the phosphor of Patent Document 1, and improvement of the fluorescence properties is required. Furthermore, the phosphor of Non-Patent Document 2 has internal quantum efficiency, absorbance, and external quantum efficiency comparable to those of Patent Document 1, but its fluorescence peak wavelength is approximately 1100 nm. Note that the fluorescence properties of the phosphors of Patent Document 1 and Non-Patent Document 2 cannot be said to be good at all, and further improvement is required.

[0018]

[0019] The near-infrared phosphor of this embodiment is capable of emitting fluorescence that can be detected with good sensitivity even by a Si-based sensor whose maximum measurable wavelength is approximately 1000 nm, and furthermore, is a phosphor with excellent fluorescent properties.

[0020] [Near-infrared phosphor] The near-infrared phosphor of this embodiment is a compound Mg ２ GeO ４ The near-infrared phosphor of this embodiment has an orthorhombic crystal structure similar to that of the inorganic compound represented by the following general formula (1), and is formed by adding Cr ions to the inorganic compound represented by the following general formula (1). ３＋ It has been replaced by (MA ｐ MC ｑ ) ｚ (MB ２ｒ ) １－ｚ (MD) ｓ O ４ ... (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, and z satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, and 0.01≦z≦0.49.

[0021] The near-infrared phosphor of this embodiment is a compound Mg ２ GeO ４ It has the same orthorhombic crystal structure as Mg ２ GeO ４ and LiScGeO ４ The Cr-activated phosphor has a solid solution of Mg as its host crystal. ２ GeO ４ and LiScMg ２ Ge ２ O ８ It is also a Cr-activated phosphor having a host crystal with an intermediate composition between

[0022] 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.

[0023] 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). MA is preferably at least one of lithium and sodium, and is preferably lithium. 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, external quantum efficiency, and light absorptance.

[0024] 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.

[0025] 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 magnesium. By using these elements as MB, it is possible to improve the fluorescent properties of the wavelength-converted light emitted from the near-infrared phosphor, particularly the internal quantum efficiency, external quantum efficiency, and light absorptance.

[0026] 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.

[0027] Note that MC may be at least one selected from the group consisting of scandium (Sc), yttrium (Y), lutetium (Lu), aluminum (Al), gallium (Ga), and indium (In). Furthermore, MC is preferably scandium, aluminum, or gallium. 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, external quantum efficiency, and light absorptance.

[0028] 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.

[0029] 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). The MD is preferably silicon or 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, external quantum efficiency, and light absorptance.

[0030] 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.

[0031] In general formula (1), z satisfies 0.01≦z≦0.49. In general formula (1), when the z value is within this range, the peak wavelength of the fluorescence emitted from the near-infrared phosphor is 1000 nm or less, and it can be detected with high sensitivity even with a Si-based sensor such as a CMOS using silicon. In addition, when the z value is within this range, it is possible to improve the fluorescence characteristics, particularly the internal quantum efficiency, external quantum efficiency, and light absorptance.

[0032] In the general formula (1), when z=0, the phosphor described in Non-Patent Document 1 is included. However, as mentioned above, the Mg ２ GeO ４ The LiMg:Cr phosphor has a fluorescence peak wavelength of about 900 nm and can be suitably used in Si-based sensors, but its fluorescence properties are insufficient. Furthermore, when z=0.5, the phosphor described in Patent Document 1 is included. However, the LiMg ２ M １－ｘ Ge ２ O ８ : x% Cr ３＋ The fluorescent material has a peak fluorescence wavelength of about 1000 nm, and when a Si-based sensor is used, a shorter wavelength is required. Furthermore, the fluorescent properties of the fluorescent material disclosed in Patent Document 1 cannot be said to be good at all.

[0033] However, the near-infrared phosphor of this embodiment is not Mg ２ GeO ４ : Cr phosphor and LiMg described in Patent Document 1 ２ M １－ｘ Ge ２ O ８ : x% Cr ３＋ The near-infrared phosphor of this embodiment has not merely an intermediate value of the fluorescent properties of the 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 element, 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.

[0034] In general formula (1), z preferably satisfies 0.05≦z≦0.45, and more preferably satisfies 0.1≦z≦0.4. When the z value in general formula (1) is within this range, the fluorescent properties of the fluorescence emitted from the near-infrared phosphor can be further improved. Furthermore, when the z value is within the above range, the emission peak wavelength of the near-infrared light emitted from the near-infrared phosphor can be further shortened.

[0035] The near-infrared phosphor of this embodiment is a phosphor that absorbs excitation light emitted by a solid-state light-emitting element and converts it into wavelength-converted light containing near-infrared light. ３＋Because it contains ions, 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 the near-infrared phosphor to be excited with high efficiency, 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 the near-infrared phosphor to be excited with relatively low-energy red light, resulting in a near-infrared light-emitting device with little heat generation due to Stokes loss of the phosphor. It is preferable that the near-infrared phosphor emits fluorescence when irradiated with excitation light having a wavelength of 450 nm.

[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 3.0 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 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 preferably has a maximum fluorescence intensity within a wavelength range of 800 nm to 1000 nm, and more preferably within a wavelength range of 900 nm to 1000 nm. This allows for high-sensitivity detection even with relatively inexpensive Si-based sensors.

[0038] 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.

[0039] 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.

[0040] As described above, the near-infrared phosphor of this embodiment contains Mg ２ GeO ４ and is a phosphor obtained by adding Cr ions to an inorganic compound represented by the following general formula (1): ｐ MC ｑ ) ｚ (MB ２ｒ ) １－ｚ (MD) ｓ O ４ ... (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, and z satisfy the following relationships: 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, 0.01≦z≦0.49.

[0041] The near-infrared phosphor of this embodiment, having such a composition, can emit fluorescence that can be detected with high sensitivity even with relatively inexpensive Si-based sensors, and can also have excellent fluorescence properties. Therefore, this 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 900 to 1000 nm, a broad near-infrared spectrum can be obtained by combining it with other near-infrared phosphors. As a result, it is possible to produce lighting for near-infrared sensing with higher accuracy.

[0042] 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.

[0043] The near-infrared phosphor of this embodiment is Mg ２ GeO ４ (1-z)MB is a phosphor having the same orthorhombic crystal structure as that of (1-z)MB, and is formed by adding Cr ions to an inorganic compound represented by the following general formula (2): ２ MD １ O ４ ・zMA １ MC １ 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. z satisfies 0.01≦z≦0.49.

[0044] The near-infrared phosphor of this embodiment is MB ２ MD １ O ４ and MA １ MC １ MD １ O ４ Since the inorganic compound having a solid solution of Zn and Cu as the host crystal, the inorganic compound can also be expressed as shown in general formula (2).

[0045] [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.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 fluorescence intensity within a blue wavelength range of 435 nm or more and less than 480 nm.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 rare earth 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:

[0061] 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.

[0062] 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 magnesium or an alkaline earth metal, and is, 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.

[0063] Among these, it is preferable that the visible phosphor contains at least one phosphor selected from the group consisting of YAG, CASN, and SCASN.

[0064] 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.

[0065] 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.

[0066] [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.

[0067] 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 disperses the transmitted light 11. The spectroscope 6 is a near-infrared spectroscope, and one equipped with a relatively inexpensive Si-based sensor can be used.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] [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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0081] (Technology 1) Mg ２ GeO ４ A near-infrared phosphor having the same orthorhombic crystal structure as that of the inorganic compound represented by general formula (1) and doped with Cr ions. ｐ MC ｑ ) ｚ (MB ２ｒ ) １－ｚ (MD) ｓ O ４ ... (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, and z satisfy 0.8≦p≦1.2, 0.8≦q≦1.2, 0.8≦r≦1.2, 0.8≦s≦1.2, and 0.01≦z≦0.49.)

[0082] This configuration allows the fluorescence peak wavelength of the fluorescence emitted from the near-infrared phosphor to be 1000 nm or less, enabling detection with high sensitivity even with a Si-based sensor. Furthermore, since the near-infrared phosphor has excellent fluorescent properties, a highly efficient near-infrared light-emitting device can be obtained.

[0083] (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.

[0084] 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.

[0085] (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 an alkaline earth metal element.

[0086] This configuration makes it possible to obtain a near-infrared phosphor that emits fluorescence that can be detected with high sensitivity even by a Si-based sensor and has excellent fluorescence properties.

[0087] (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 Li; (2) MB is Mg; (3) MC is Sc, Ga, or Al; (4) MD is Ge or Si.

[0088] This configuration makes it possible to obtain a near-infrared phosphor that emits fluorescence that can be detected with high sensitivity even by a Si-based sensor and has excellent fluorescence properties.

[0089] (Technology 5) In the general formula (1), MA is Li, MB is Mg, MC is Sc, Ga or Al, and MD is Ge or Si, a near-infrared phosphor according to any one of technologies 1 to 4.

[0090] This configuration makes it possible to obtain a near-infrared phosphor that emits fluorescence that can be detected with high sensitivity even by a Si-based sensor and has excellent fluorescence properties.

[0091] (Technology 6) The near-infrared phosphor according to any one of Technologies 1 to 5, which is a powder phosphor or a fluorescent ceramic.

[0092] 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.

[0093] (Technology 7) A near-infrared light emitting device comprising the near-infrared phosphor according to any one of technologies 1 to 6.

[0094] 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.

[0095] (Technology 8) The near-infrared light emitting device according to Technology 7, 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.

[0096] 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.

[0097] (Technology 9) A spectroscopic device comprising the near-infrared light emitting device according to Technology 7 or 8.

[0098] 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.

[0099] (Technology 10) A sensing device comprising the near-infrared light emitting device according to Technology 7 or 8.

[0100] This sensing device is equipped with a near-infrared light emitting device that emits near-infrared light with a fluorescence peak wavelength of 1000 nm or less with high efficiency, and therefore can be suitably used for non-contact vital sign sensing.

[0101] 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.

[0102] 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. Scandium oxide (Sc ２ O ３ ): Purity 4N, manufactured by Shin-Etsu Chemical Co., Ltd. Magnesium oxide (MgO): Purity 3N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Germanium oxide (GeO ２ ): Purity 3N, manufactured by High Purity Chemical Laboratory Co., Ltd. Chromium oxide (Cr ２ O ３ ): Purity 3N, manufactured by High Purity Chemical Laboratory Co., Ltd. Gallium oxide (Ga ２ O ３ ): Purity 4N, manufactured by Asia Physical Materials Co., Ltd. Aluminum oxide (Al ２ O ３ ): Purity 3N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Silicon oxide (SiO ２ ): Purity 3N, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.

[0103] [Preparation of Phosphor] (Example 1-1) The oxide phosphor of this example was synthesized by a preparation method using a solid-state reaction. ０．２５ (Mg ２ ) ０．７５ GeO ４ An oxide phosphor was synthesized, which is represented by the composition formula: 0.3% Cr. In the oxide phosphor, the chromium concentration is the amount of chromium substance in the amount of metal element substance.

[0104] First, a compound of stoichiometric composition (LiSc) ０．２５ (Mg ２ ) ０．７５ GeO ４The raw materials were weighed so that the Cr content was 0.3%. Then, the raw materials were dry-mixed using a mortar and pestle to prepare a firing raw material.

[0105] 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 1200°C for 4 hours, after which the fired product was lightly crushed. This gave the phosphor of this example. The phosphor composition, the z value when the phosphor is expressed by general formula (1), and the firing temperature are summarized in Table 2.

[0106] (Comparative Examples 1-2 to 1-5) 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 1-2 corresponds to the phosphor of Patent Document 1, the phosphor of Comparative Example 1-3 corresponds to the phosphor of Non-Patent Document 1, and the phosphor of Comparative Example 1-5 corresponds to the phosphor of Non-Patent Document 2.

[0107] (Examples 2-1 to 2-2 and Comparative Examples 2-3 to 2-4) The raw materials were weighed so as to obtain the phosphor compositions shown in Table 2, and phosphors of each example were obtained by the same method as in Example 1-1, except that the firing temperature was changed to 1400°C. The phosphor of Example 2-1 is a phosphor whose firing temperature is higher than that of Example 1-1. The phosphor of Example 2-2 is a phosphor whose firing temperature is higher than that of Example 1-1 and whose z value is further reduced. The phosphor of Comparative Example 2-3 is a phosphor whose firing temperature is higher than that of Comparative Example 1-2. The phosphor of Comparative Example 2-4 is a phosphor whose firing temperature is higher than that of Comparative Example 1-3.

[0108] (Example 3-1 and Comparative Examples 3-2 to 3-3) The phosphors of each example were obtained by the same method as in Example 1-1, except that the raw materials were weighed out so as to obtain the phosphor composition shown in Table 3. The phosphor of Example 3-1 is a phosphor obtained by substituting gallium (Ga) for scandium (Sc) in the phosphor of Example 1-1 and further increasing the amount of chromium added. The phosphor of Comparative Example 3-2 is a phosphor obtained by substituting gallium (Ga) for scandium (Sc) in the phosphor of Comparative Example 1-2 and further increasing the amount of chromium added. The phosphor of Comparative Example 3-3 is a phosphor in which the amount of chromium added is higher than in Comparative Example 1-3, and corresponds to the phosphor of Non-Patent Document 1.

[0109] (Example 4-1 and Comparative Examples 4-2 to 4-3) 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 3. The phosphor of Example 4-1 is a phosphor obtained by substituting aluminum (Al) for scandium (Sc) in the phosphor of Example 1-1 and further increasing the amount of chromium added. The phosphor of Comparative Example 4-2 is a phosphor obtained by substituting aluminum (Al) for scandium (Sc) in the phosphor of Comparative Example 1-2 and further increasing the amount of chromium added. The phosphor of Comparative Example 4-3 is the same phosphor as Comparative Example 3-3.

[0110] (Example 5-1 and Comparative Examples 5-2 to 5-3) 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 3. The phosphor of Example 5-1 is a phosphor obtained by substituting silicon (Si) for germanium (Ge) in the phosphor of Example 1-1 and further increasing the amount of chromium added. The phosphor of Comparative Example 5-2 is a phosphor obtained by substituting silicon (Si) for germanium (Ge) in the phosphor of Comparative Example 1-2 and further increasing the amount of chromium added. The phosphor of Comparative Example 5-3 is a phosphor obtained by substituting silicon (Si) for germanium (Ge) in the phosphor of Comparative Example 1-3 and further increasing the amount of chromium added.

[0111]

[0112]

[0113] [Evaluation] Next, the crystal structure and fluorescent properties of the compounds constituting the phosphor were evaluated for the synthesized phosphor samples.

[0114] (Crystal Structure Analysis) For the phosphors of Example 1-1 and Comparative Examples 1-2 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.

[0115] As shown in FIG. 5, the phosphors of Example 1-1 and Comparative Examples 1-2 to 1-5 contain Mg２ GeO ４ Therefore, these phosphors show the same diffraction patterns as Mg ２ GeO ４ It can be seen that the phosphors have the same crystal structure as that of Example 1-1, Comparative Example 1-2, and Comparative Example 1-4. Furthermore, it can be seen from FIG. 5 that the diffraction lines shift to the lower angle side as the z value increases. Therefore, in the phosphors of Example 1-1, Comparative Example 1-2, and Comparative Example 1-4, Mg ２ GeO ４ and LiScGeO ４ It is presumed that all of the elements are in solid solution.

[0116] Therefore, the phosphor of Example 1-1 contains the compound Mg ２ GeO ４ It has the same orthorhombic crystal structure as Mg ２ GeO ４ and LiScGeO ４ It can be seen that the phosphor of Example 1-1 is a Cr-activated phosphor having a solid solution of Mg ２ GeO ４ and LiScMg ２ Ge ２ O ８ It can also be seen that this is a Cr-activated phosphor with a host crystal having an intermediate composition between

[0117] (Fluorescence Properties) Using a Quantaurus-QY Plus (expanded absolute PL quantum yield measurement device with heating mechanism) C13534-02 (manufactured by Hamamatsu Photonics K.K.), the fluorescence properties of the phosphor were measured when excited at an excitation wavelength of 450 nm. The measured fluorescence properties were the internal quantum efficiency (IQE) at wavelengths of 600 nm to 1600 nm, the light absorption coefficient (Abs.), 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.

[0118] As shown in Table 2, the phosphor of Example 1-1 has a fluorescence peak wavelength of 960 nm, which is below 1000 nm, which can be detected with high sensitivity by a Si-based sensor. Furthermore, it is found that the phosphor of Example 1-1 has improved internal quantum efficiency and light absorption rate compared to the phosphors of Comparative Examples 1-2 to 1-5. Furthermore, it is found that the phosphor of Example 1-1 has a half-width exceeding 250 nm.

[0119] Furthermore, it can be seen from Examples 1-1 and 2-1 that the fluorescence peak wavelength can be further shortened while increasing the amount of Cr added and the firing temperature when preparing the phosphor. Furthermore, it can be seen from Example 2-2 and Comparative Examples 2-3 and 2-4 that when the z value is changed to 0.1, the fluorescence peak wavelength can be further shortened while suppressing the decrease in internal quantum efficiency.

[0120] Furthermore, from Example 3-1 and Comparative Examples 3-2 and 3-3 shown in Table 3, it can be seen that even when scandium in the phosphor of Example 1-1 is replaced with gallium, the internal quantum efficiency is good and the fluorescence peak wavelength can be shortened to less than 900 nm.

[0121] From Example 4-1 and Comparative Examples 4-2 and 4-3, it can be seen that even when scandium in the phosphor of Example 1-1 is replaced with aluminum, the internal quantum efficiency and light absorption rate are good, and furthermore, the fluorescence peak wavelength can be shortened to less than 950 nm.

[0122] From Example 5-1 and Comparative Examples 5-2 and 5-3, it can be seen that even when germanium in the phosphor of Example 1-1 is replaced with silicon, the internal quantum efficiency and light absorption rate are good, and furthermore, the fluorescence peak wavelength can be shortened to less than 950 nm.

[0123] Table 4 summarizes the compositions, z values, internal quantum efficiency (IQE), optical absorptivity (Abs.), external quantum efficiency (EQE), and fluorescence peak wavelengths of the phosphors of Example 1-1 and Comparative Examples 1-2, 1-3, and 1-5. The external quantum efficiency was measured using a Quantaurus-QY Plus (extended absolute PL quantum yield measurement system with heating mechanism) C13534-02 (manufactured by Hamamatsu Photonics K.K.) with excitation at a wavelength of 450 nm. Figure 6 shows the emission spectra of the phosphors of Example 1-1 and Comparative Examples 1-2, 1-3, and 1-5 when excited at a wavelength of 450 nm.

[0124] As described above, the phosphor of Example 1-1 contains the compound Mg ２ GeO ４ It has the same orthorhombic crystal structure as Mg ２ GeO ４ and LiScMg ２ Ge ２ O ８ It is a Cr-activated phosphor having a host crystal with an intermediate composition between the above. However, it can be seen that the internal quantum efficiency, light absorption rate, and external quantum efficiency of the phosphor of Example 1-1 are improved compared to those of Comparative Examples 1-2, 1-3, and 1-5. In other words, the fluorescent properties of the phosphor of Example 1-1 are not simply intermediate values ​​between the fluorescent properties of the phosphors of Comparative Examples 1-2 and 1-3, but are surprisingly improved compared to these phosphors. Furthermore, since the fluorescent peak wavelength of the phosphor of Example 1-1 is 1000 nm or less, it can be detected with good sensitivity even with a relatively inexpensive Si-based sensor.

[0125]

[0126] 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.

[0127] The entire contents of Japanese Patent Application No. 2024-007866 (filing date: January 23, 2024) are incorporated herein by reference.

[0128] According to the present disclosure, it is possible to provide a near-infrared phosphor that can emit fluorescence that can be detected with high sensitivity even by a Si-based sensor and has excellent fluorescent properties, and a near-infrared light-emitting device that includes the near-infrared phosphor. According to the present disclosure, it is also possible to provide a spectroscopic device and a sensing device that include the near-infrared light-emitting device.

[0129] 1 Solid-state light-emitting element 100 Near-infrared light-emitting device 200 Spectroscopic device

Claims

1. Mg ２ GeO ４ and having the same orthorhombic crystal structure, a near-infrared phosphor obtained by adding Cr ions to an inorganic compound represented by the general formula (1). (MA ｐ MC ｑ ) ｚ (MB ２ｒ ) １－ｚ (MD) ｓ O ４ ... (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, and z satisfy 0.8 ≤ p ≤ 1.2, 0.8 ≤ q ≤ 1.2, 0.8 ≤ r ≤ 1.2, 0.8 ≤ s ≤ 1.2, and 0.01 ≤ z ≤ 0.49.) 2. 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 full width at half maximum of the spectrum having the maximum fluorescence intensity exceeds 100 nm. The near-infrared phosphor according to claim 1.

3. In general formula (1), MA is an alkali metal element and MB is an alkaline earth metal element. The near-infrared phosphor according to claim 1 or 2.

4. General formula (1) satisfies at least one of the following (1) to (4). The near-infrared phosphor according to any one of claims 1 to 3: (1) MA is Li; (2) MB is Mg; (3) MC is Sc, Ga or Al; (4) MD is Ge or Si.

5. In general formula (1), MA is Li, MB is Mg, MC is Sc, Ga or Al, and MD is Ge or Si. The near-infrared phosphor according to any one of claims 1 to 4.

6. The near-infrared phosphor according to any one of claims 1 to 5, which is a powdered phosphor or a fluorescent ceramic.

7. A near-infrared light-emitting device comprising the near-infrared phosphor according to any one of claims 1 to 6.

8. Further comprising a solid light-emitting element, wherein the near-infrared phosphor is excited by the excitation light emitted by the solid light-emitting element. The near-infrared light-emitting device according to claim 7.

9. A spectroscopic device comprising the near-infrared light-emitting device according to claim 7 or 8.

10. A sensing device comprising the near-infrared light-emitting device according to claim 7 or 8.

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