Near-infrared fluorescent powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of luminescent materials, and particularly discloses near-infrared fluorescent powder as well as a preparation method and application thereof, and the chemical general formula of the near-infrared fluorescent powder is Gd3Ga5-x-yAlxO12-xNx: yCr < 3 + >, wherein x and y both represent mole fractions, the value ranges of x and y are as follows: x is more than or equal to 0.1 and less than or equal to 4.0, and y is more than or equal to 0.001 and less than or equal to 0.5. Compared with the existing near-infrared fluorescent powder, the near-infrared fluorescent powder disclosed by the invention has high light-emitting external quantum efficiency and excellent light-emitting thermal stability. The near-infrared fluorescent powder provided by the invention is based on a blue light LED chip, and a broadband near-infrared LED with relatively high radiation power can be obtained. The near-infrared fluorescent powder can also be applied to the field of radiation refrigeration, and color adjustment is achieved on the basis that the refrigeration effect is not changed.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and in particular to a near-infrared phosphor and a preparation method and application thereof. Background Art

[0002] Broadband near-infrared spectroscopy technology has been widely used in biological tissue and crop detection and analysis due to its advantages such as non-destructive properties, strong penetration, and characteristic absorption. Traditional near-infrared light sources, such as tungsten filament lamps, suffer from high energy consumption and large size. Near-infrared LED chips, on the other hand, are highly efficient, compact, and inexpensive, but their emission band is narrow, typically less than 50nm, and cannot meet the application requirements of broadband spectrum. In 2017, OSRAM pioneered a technical solution based on blue LED chips to excite broadband near-infrared phosphors, creating a new generation of small broadband near-infrared light sources. In recent years, fluorescent conversion materials that can be effectively excited by blue light and exhibit broadband near-infrared emission characteristics have become a research hotspot.

[0003] Zhang Liangliang et al. from the Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences reported Ca3Hf2Al2SiO 12 :Cr 3+ The emission spectrum is 700~1000nm, the half-height width is 117nm, the external quantum efficiency is 31.5%, the thermal stability is 60% at 423K, the conversion efficiency is 15.75% at a driving current of 100mA, and the output power is 46.09mW (Cr 3+ -dopedbroadband NIR garnet phosphor with enhanced luminescence and its application in NIR spectroscopy, Advanced Optical Materials, 2019, 7, 1900185). Jia Zhenwei et al. from Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences reported Ca3Sc2Si3O 12 :Cr 3+ Its emission spectrum is 700~1100nm, the half-maximum width is 110nm, the external quantum efficiency reaches 25.5%, the thermal stability is 97.3% at 423K, and the output power at 520mA driving current is 109.9mW (Strategies to approach high performance in Cr 3+-doped phosphors for high-power NIR-LED light sources, Light: Science & Applications, 2020, 9: 86). Xie Rongjun et al. from Xiamen University reported Y2CaAl4Si2O 12 , with an emission bandwidth of 160 nm, an external quantum efficiency of 28.1%, and a thermal stability of ~88% at 423 K (Broadband near-infrared (NIR) emission realized by the crystal-field engineering of Y 3-x Ca x Al 5-x Si x O 12 :Cr 3+ (x = 0-2.0) garnetphosphors, Journal of Materials Chemistry C, 2020, 8: 1981-1988). Lei Bingfu et al. from South China Agricultural University reported that Gd 2.4 Lu 0.6 Ga4AlO 12 :Cr 3+ The emission spectrum bandwidth is 107nm, the external quantum efficiency reaches 32.0%, and the thermal stability at 423K is 75% (A highly efficient and suitable spectral profile Cr 3+ -doped garnet near-infrared emitting phosphorus for regulating photomorphogenesis of plants, Chemical Engineering Journal, 2022, 428: 132003). Cai Gemei et al. from Central South University reported Y2Mg2Al2Si2O 12 The emission bandwidth is 150nm, the external quantum efficiency is 29.2%, the thermal stability at 423K is 70.2%, the output power of the device is 17mW when driven by 100mA current, and the conversion efficiency is 6.3% (Achieving broadband near-infrared luminescence in Cr 3+ -Activated Y2Mg2Al2Si2O 12phosphorsvia multi-site occupancy, Advanced Powder Materials, 2024, 3: 100186). Liu Yongfu et al. from Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences reported Gd3Ga5O 12 :Cr 3+ ,Si3N4, emission bandwidth is 116nm, thermal stability at 423K is 98.7%, external quantum efficiency is 28%, and the output power of the device is 47.1mW under 100mA current drive, with a conversion efficiency of 15.9% (Enhanced Thermally Stability and Broadened Emissionfor Gd3Ga5O 12 :Cr 3+ Phosphors via Si3N4 Substitution, Laser Photonics & Reviews, 2025, 19: 2401163).

[0004] In summary, near-infrared devices based on reported near-infrared fluorescent materials have an output power range of 17–47.1 mW and a photoelectric conversion efficiency of 6.3–15.9% when driven by a current of 100 mA. The high temperatures generated by long-term LED operation can cause the performance of near-infrared luminescent materials to degrade. To achieve high-performance near-infrared LED devices, it is urgent to develop near-infrared fluorescent materials that can be effectively excited by blue LED chips, exhibit high efficiency, and exhibit good thermal stability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the efficiency and thermal stability of existing near-infrared fluorescent materials are not high enough. In order to overcome the above defects of the existing technology, the present invention provides a near-infrared phosphor and its preparation method and application.

[0006] The present invention provides a near-infrared phosphor: the chemical formula of the near-infrared phosphor is Gd3Ga 5-x- y AlxCr y O 12-x N x ; Wherein: x, y represent the mole fraction of the corresponding element, and 0.1≤x≤4.0, 0.001≤y≤0.5.

[0007] Compared with the prior art, the present invention has the following advantages: the near-infrared phosphor can be effectively excited by blue light, has high luminous efficiency and good thermal stability.

[0008] In a possible implementation, the value ranges of x and y are: 0.4≤x≤1.5, 0.02≤y≤0.20.

[0009] In a possible implementation, the excitation wavelength of the near-infrared phosphor is 420 nm to 470 nm; and the emission spectrum of the near-infrared phosphor is 650 nm to 850 nm.

[0010] In a possible implementation, the external quantum efficiency of the near-infrared phosphor is 43.5% to 44.8%.

[0011] Another aspect of the present invention provides a method for preparing a near-infrared phosphor, comprising the following steps: selecting reaction raw materials from a Gd source, a Ga source, an Al source, and a Cr source according to the molar ratio of each element in the chemical formula of the phosphor, mixing, sintering, and grinding the selected reaction raw materials to obtain the near-infrared phosphor.

[0012] In one possible embodiment, the Gd source is selected from at least one of Gd oxides, fluorides, carbonates, borates, oxalates, and acetates; the Ga source is selected from at least one of Ga oxides, fluorides, carbonates, borates, oxalates, and acetates; the Al source is selected from at least one of Al nitrides and nitrogen oxides; and the Cr source is selected from at least one of Cr oxides, fluorides, carbonates, borates, oxalates, and acetates.

[0013] In one possible implementation, the Gd source is selected from Gd oxides; the Ga source is selected from Ga oxides; the Al source is selected from Al nitrides; and the Cr source is selected from Cr oxides.

[0014] In a possible implementation, the specific conditions for sintering include: the sintering atmosphere is an air atmosphere; the sintering temperature is 1400-1650° C.; and the sintering time is 1-5 hours.

[0015] In a possible implementation manner, the sintering temperature is 1450° C. to 1600° C., and the heating rate is 3° C. to 10° C. / min.

[0016] In one possible embodiment, a sintering aid H3BO3 or Li2CO3 is added during the sintering process, and the amount of the sintering aid added accounts for 0.5wt%~8wt% of the total raw materials; the sintering temperature after adding the sintering aid is 1250℃~1400℃, and the heating rate is 3~10℃ / min.

[0017] Another aspect of the present invention provides a near-infrared LED light source, wherein the chip of the near-infrared LED light source is a blue LED chip, and the phosphor is the near-infrared phosphor according to any one of claims 1 to 4.

[0018] Another aspect of the present invention provides use of the near-infrared phosphor according to any one of claims 1 to 4 in radiative cooling.

[0019] The beneficial effects of the present invention are: 1) Compared with existing near-infrared phosphors, the near-infrared phosphor provided by the present application is a garnet near-infrared phosphor, which has excellent thermal stability and can still maintain good luminescence performance at higher temperatures. The luminescence thermal stability at 523K maintains 92%~110% of that at room temperature.

[0020] 2) Compared with existing near-infrared phosphors, the near-infrared phosphor provided in this application has high luminous efficiency and excellent device photoelectric conversion efficiency under blue light excitation. The near-infrared light output power is 65.4 mW at 100 mA, and the device photoelectric conversion efficiency reaches 22.1% at 100 mA.

[0021] 3) Compared with existing near-infrared phosphors, the near-infrared phosphor provided in this application can be used in the field of radiative cooling.

[0022] 4) The near-infrared phosphor provided in this application is synthesized and studied for the first time in the field of luminescent materials. It is prepared by a high-temperature solid-phase method, which is low-cost, simple in process, with a low sintering temperature, energy saving, and the obtained product quality is stable and reliable, which is very conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the excitation spectrum of the near-infrared phosphor prepared in Example 5 of the present application, wherein the wavelength of the emitted light λem=730nm; Figure 2 This is the emission spectrum of the near-infrared phosphor prepared in Example 6 of the present application, wherein the wavelength of the excitation light λex=450nm; Figure 3 This is a comparison chart of the temperature-dependent spectral intensity of the near-infrared phosphors of Example 8 and Comparative Example 1 of the present application; Figure 4 This is a comparison chart of the external quantum efficiency of the near-infrared phosphors of Examples 6, 7, and 8 of the present application and Comparative Example 1; Figure 5 This is the electroemission spectrum of the near-infrared LED light source of Example 9 of the present application; Figure 6 The photoelectric conversion efficiency of the near-infrared LED light source of Example 9 of the present application; Figure 7 The temperature, atmospheric temperature, and total radiation diagram of the radiant cooling building material mixed with near-infrared phosphor in Example 10 of the present application and the radiant cooling building material without near-infrared phosphor in Comparative Example 2 were placed outdoors for 3 days. DETAILED DESCRIPTION

[0024] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0025] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0026] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments was carried out in accordance with the protocols and parameters given by the manufacturers.

[0027] In the embodiment of the present invention, the chemical formula of the near-infrared phosphor is Gd3Ga 5-x-y AlxCr y O 12-x N x Wherein: x and y represent the mole fractions of the corresponding elements, and 0.1≤x≤4.0, 0.001≤y≤0.5. Preferably, the values ​​of x and y are in the range of 0.4≤x≤1.5, 0.02≤y≤0.20. Within this range, the obtained near-infrared phosphor has better luminescence performance.

[0028] Another aspect of the present invention provides a method for preparing the above-mentioned near-infrared phosphor, the method comprising at least the following steps: S1, providing raw materials and grinding and mixing them to obtain a mixture; S2, sintering the mixture in an air atmosphere to obtain a sintered body; S3, grinding the sintered body to obtain near-infrared phosphor.

[0029] In step S1, according to Gd3Ga 5-x-y AlxCr y O 12-x Nx The corresponding raw materials containing Gd, Ga, Al, and Cr sources are weighed in a stoichiometric ratio. Commercially available micron- or nanoscale raw materials with a purity of 99% or higher can be used, eliminating the need for reprocessing, which saves costs and facilitates industrialization. Optionally, in step S1, the Gd source includes at least one of Gd oxides, carbonates, and phosphates; the Ga source includes at least one of Ga oxides, carbonates, and phosphates; the Al source includes at least one of Al nitrides and oxynitrides; and the Cr source includes at least one of Cr oxides, carbonates, and phosphates.

[0030] Optionally, in step S1, the Gd source is selected from oxides containing element Gd; the Ga source is selected from Ga oxides; the Al source is selected from Al nitrides; and the Cr source is selected from Cr oxides.

[0031] Grind the prepared raw materials for 15-240 minutes to mix them evenly, until the resulting powder particle size is 80-400 mesh. This grinding can be performed in an agate mortar or ball mill. Adding alcohol or acetone to the raw materials during the grinding process can accelerate the grinding process.

[0032] In step S2, the sintering temperature is selected to be 1400-1650°C, the sintering time is 1-5 hours, and the sintering atmosphere is air. Preferably, the sintering temperature is 1450-1600°C, and the heating rate is selected to be 3-10°C / minute.

[0033] Optionally, a sintering aid can be added during the sintering process to lower the sintering temperature and increase the material's crystallinity, further saving costs and facilitating industrialization. Sintering aids such as H₃BO₃ and Li₂CO₃ can be used, with the content ranging from 0.5wt% to 10wt%. The sintering temperature after adding the sintering aid is 1250°C to 1400°C, with a heating rate of 3°C / minute to 10°C / minute.

[0034] Optionally, the sintering process can be performed in an air atmosphere or a nitrogen atmosphere.

[0035] In step S3, the grinding time is 15 to 60 minutes, and the obtained powder particle size is 80 to 400 mesh.

[0036] Another aspect of the present invention provides the use of the near-infrared phosphor prepared by any of the above methods as a near-infrared LED light source and in radiation cooling.

[0037] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The raw materials used for preparing the near-infrared phosphor of the present invention are Gd2O3, Ga2O3, AlN, Cr2O3 and H3BO3 with a commercial purity of more than 99%. Example 1

[0039] When x=0.1, y=0.001, the chemical formula of the near-infrared phosphor is Gd3Ga 4.989 Al 0.1 Cr 0.001 O 11.9 N 0.1 .

[0040] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, and Cr2O3 were weighed as reaction raw materials. Ethanol was added to the weighed reaction raw materials in an agate mortar, mixed, and ground for 15 minutes to obtain a mixture.

[0041] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1400°C for 5 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 2

[0042] When x=4.0, y=0.5, the chemical formula of the near-infrared phosphor is Gd3Ga 0.5 Al 4.0 Cr 0.5 O8N4.

[0043] The preparation method of the near-infrared phosphor is as follows: According to the above ratio, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, and Cr2O3 were weighed as reaction raw materials, and the weighed reaction raw materials were mixed and ground in a ball mill for 240 minutes to obtain a mixture.

[0044] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1650°C for 1 hour in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 3

[0045] When x=0.4, y=0.02, the chemical formula of the near-infrared phosphor is Gd3Ga 4.58 Al 0.4 Cr 0.02 O 11.6 N 0.4 .

[0046] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, and Cr2O3 were weighed as reaction raw materials, and the weighed reaction raw materials were mixed and ground in an agate mortar for 45 minutes to obtain a mixture.

[0047] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1500°C for 3 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 4

[0048] When x=1.5 and y=0.2, the chemical formula of the near-infrared phosphor is Gd3Ga 3.3 Al 1.5 Cr 0.2 O 10.5 N 1.5 .

[0049] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, and Cr2O3 were weighed as reaction raw materials, and the weighed reaction raw materials were mixed and ground in an agate mortar for 60 minutes to obtain a mixture.

[0050] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1450°C for 2 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 5

[0051] When x=1.5, y=0.08, the chemical formula of the near-infrared phosphor is Gd3Ga 3.42 Al 1.5 Cr 0.08 O 10.5 N 1.5 .

[0052] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, and Cr2O3 were weighed as reaction raw materials, and the weighed reaction raw materials were mixed and ground in an agate mortar for 30 minutes to obtain a mixture.

[0053] The mixture is placed in a high-purity corundum crucible and sintered at 1500°C for 2 hours in a high-temperature box furnace under air atmosphere. After cooling to room temperature, the obtained body is ground into powder, which is the near-infrared phosphor. Example 6

[0054] When x=1.0, y=0.08, the chemical formula of the near-infrared phosphor is Gd3Ga 3.92 Al1.0 Cr 0.08 O 11 N 1.0 .

[0055] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, Cr2O3, and H3BO3 were weighed as reaction raw materials, wherein the H3BO3 content was 0.5 wt%. The weighed reaction raw materials were mixed and ground in an agate mortar for 40 minutes to obtain a mixture.

[0056] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1400°C for 4 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 7

[0057] When x=0.6, y=0.08, the chemical formula of the near-infrared phosphor is Gd3Ga 4.34 Al 0.6 Cr 0.08 O 11.4 N 0.6 .

[0058] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, Cr2O3, and H3BO3 were weighed as reaction raw materials, wherein the H3BO3 content was 8 wt%. The weighed reaction raw materials were mixed and ground in an agate mortar for 30 minutes to obtain a mixture.

[0059] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1250°C for 1 hour in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 8

[0060] When x=0.8, y=0.08, the chemical formula of the near-infrared phosphor is Gd3Ga 4.12 Al 0.8 Cr 0.08 O 11.2 N 0.8 .

[0061] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, AlN, Cr2O3, and H3BO3 were weighed as reaction raw materials, wherein the H3BO3 content was 3 wt%. The weighed reaction raw materials were mixed and ground in an agate mortar for 30 minutes to obtain a mixture.

[0062] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1330°C for 2 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Example 9

[0063] The near-infrared phosphor of Example 8 and epoxy resin were uniformly mixed at a mass ratio of 6:4 and coated on a blue LED chip. The mixture was dried in an oven at 60° C. for 10 minutes to obtain a near-infrared LED light source. Example 10

[0064] The near-infrared phosphor of Example 8 was evenly mixed with the transparent cooling slurry to obtain a green slurry, which was then applied on the building material and dried naturally to obtain a green radiation cooling building material. Comparative Example 1

[0065] When x=0, y=0.08, the chemical formula of the near-infrared phosphor is Gd3Ga5Cr 0.08 O 12 .

[0066] The preparation method of the near-infrared phosphor is as follows: According to the above formula, commercially available high-purity (99%) Gd2O3, Ga2O3, Cr2O3, and H3BO3 were weighed as reaction raw materials, wherein the H3BO3 content was 3 wt%. The weighed reaction raw materials were mixed and ground in an agate mortar for 30 minutes to obtain a mixture.

[0067] The mixture is placed in a high-purity corundum crucible and sintered in a high-temperature box furnace at 1330°C for 2 hours in an air atmosphere. After cooling to room temperature, the resulting body is ground into powder, which is the near-infrared phosphor. Comparative Example 2

[0068] White radiant cooling building materials are obtained by scraping transparent radiant cooling slurry on building materials and drying them naturally. Performance testing:

[0069] The excitation spectrum, emission spectrum, and temperature-varying spectrum in the present invention were obtained by testing with an F311 spectrometer produced by Horiba, Japan. The quantum efficiency was obtained by testing with a QE2100 quantum efficiency tester produced by Otsuka, Japan.

[0070] The samples obtained in Examples 1-8 were subjected to excitation spectrum analysis. Typically, taking the sample obtained in Example 5 as an example, Figure 1 The excitation spectrum of the near-infrared phosphor obtained in Example 5 is fixed at a wavelength of 730 nm. Figure 1As shown in Figure 1, the excitation spectrum of the near-infrared phosphor covers 400~700nm, of which the optimal excitation range covers the blue light region of 420nm~470nm, and the strongest peak is located near 450nm, which is well matched with the emission spectrum of commercial blue light LED chips. Figure 1 The near-infrared phosphors of the present invention can be effectively excited by 420nm-470nm blue light. Therefore, the near-infrared phosphors of the present invention can be combined with commercial blue light LED chips to prepare near-infrared LED light sources.

[0071] The samples obtained in Examples 1-8 were subjected to emission spectrum analysis. Typically, taking the sample obtained in Example 6 as an example, Figure 2 This is the emission spectrum of the near-infrared phosphor obtained in Example 6. Figure 2 It can be seen that under the excitation of 450nm blue light, the near-infrared phosphor in Example 6 has a broad emission band. The emission spectrum covers the wavelength range of 650nm to 850nm, with the strongest peak of the emission spectrum located near 730nm, and the half-width of the emission spectrum can reach 95nm.

[0072] The samples obtained in Examples 1-8 and Comparative Example 1 were subjected to temperature-dependent emission spectroscopy analysis. Typically, taking the samples obtained in Example 8 and Comparative Example 1 as examples, Figure 3 The figure shows the trend of the integrated luminescence intensity of Comparative Example 1 and Example 8 at different temperatures. The thermal stability of the luminescence of Comparative Example 1 is 85% at 523K, while that of Example 8 is 110%. The thermal stability of the luminescence of Examples 1-7 ranges from 92% to 108%. This indicates that the samples prepared according to the present invention have superior thermal stability.

[0073] The external quantum efficiency of the samples obtained in Examples 1-8 and Comparative Example 1 was analyzed. Typically, taking the samples obtained in Examples 6, 7, 8 and Comparative Example 1 as examples, Figure 4 The external quantum efficiency test results of Examples 6, 7, 8 and Comparative Example 1 are shown in FIG. Figure 4 As can be seen, the external quantum efficiency of luminescence in Comparative Example 1 is only 31.1%, while the external quantum efficiencies of the near-infrared phosphors obtained in Examples 6, 7, and 8 are 43.5%, 44.8%, and 44.8%, respectively, which are relatively high among currently known near-infrared phosphors. This demonstrates that the near-infrared phosphors of the present invention have superior luminescence efficiency compared to existing near-infrared phosphors.

[0074] Electroluminescence spectrum analysis was performed on the samples obtained in Examples 1-8. Typically, taking the near-infrared light source obtained in Example 9 as an example, Figure 5This is the electroemission spectrum of the near-infrared LED light source prepared in Example 9. In the figure, the emission spectrum from 400nm to 500nm comes from the luminescence of the 450nm blue light chip, and the emission spectrum from 650nm to 850nm comes from the luminescence of the near-infrared phosphor.

[0075] In the background of the invention, the near-infrared device constructed based on the known related near-infrared luminescent materials has an output power of 17~47.1mW and a photoelectric conversion efficiency of 6.3~15.9% under a 100mA current drive. The photoelectric conversion efficiency of the near-infrared LED device prepared in Example 9 of the present invention is as follows: Figure 6 As shown in the figure, the near-infrared light output power is 65.4 mW at 100 mA, and the photoelectric conversion efficiency is 22.1%, indicating that the device prepared based on the near-infrared phosphor of the present invention has better performance than existing near-infrared devices.

[0076] Figure 7 The following graphs show the temperature, atmospheric temperature, and total radiation of the green radiant cooling building material of Example 10 and the white radiant cooling building material of Comparative Example 2, after being placed outdoors for three days. The atmospheric temperature in the graph represents the real-time atmospheric temperature over the three-day period, and the total radiation represents the real-time solar irradiance over the three-day period. Taking December 1, 2024, as an example, the atmospheric temperature reached 23°C at 2:00 PM. At this time, the temperature of both Example 10 and Comparative Example 2 was 17.5°C, a 5.5°C decrease from the atmospheric temperature. This demonstrates that the near-infrared phosphor of the present invention can adjust the color of the radiant cooling building material from white to green without affecting the radiant cooling effect.

[0077] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A near-infrared phosphor, characterized in that: The chemical formula of the phosphor is: Gd3Ga 5-x-y Al x Cr y O 12-x N x , where x and y represent the mole fractions of the corresponding elements, respectively, and 0.1≤x≤4.0, 0.001≤y≤0.

5.

2. The near-infrared phosphor according to claim 1, characterized in that: The value range of x and y is: 0.4≤x≤1.5, 0.02≤y≤0.

20.

3. The near-infrared phosphor according to claim 1, characterized in that: The excitation wavelength of the phosphor is 420 nm to 470 nm; the emission spectrum of the near-infrared phosphor is 650 nm to 850 nm; and the external quantum efficiency of the phosphor is 43.5% to 44.8%.

4. The method for preparing a near-infrared phosphor according to any one of claims 1 to 3, characterized in that: The following steps are involved: According to the molar ratio of each element in the chemical formula of the phosphor, reaction raw materials are selected from Gd source, Ga source, Al source and Cr source, and the selected reaction raw materials are mixed, sintered and ground to obtain the near-infrared phosphor.

5. The preparation method according to claim 4, characterized in that The Gd source is selected from at least one of Gd oxides, fluorides, carbonates, borates, oxalates, and acetates; the Ga source is selected from at least one of Ga oxides, fluorides, carbonates, borates, oxalates, and acetates; the Al source is selected from at least one of Al nitrides and nitrogen oxides; and the Cr source is selected from at least one of Cr oxides, fluorides, carbonates, borates, oxalates, and acetates.

6. The preparation method according to claim 5, characterized in that The Gd source is selected from Gd oxides; the Ga source is selected from Ga oxides; the Al source is selected from Al nitrides; and the Cr source is selected from Cr oxides.

7. The preparation method according to claim 4, characterized in that The specific conditions of the sintering include: the sintering atmosphere is air atmosphere; the sintering temperature is 1400~1650℃; the sintering time is 1~5h; Preferably, the sintering temperature is 1450° C. to 1600° C., and the heating rate is 3° C. to 10° C. / min.

8. The preparation method according to claim 4, characterized in that During the sintering process, a sintering aid H3BO3 or Li2CO3 is added, and the amount of the sintering aid added accounts for 0.5wt%~8wt% of the total raw materials; the sintering temperature after adding the sintering aid is 1250℃~1400℃, and the heating rate is 3~10℃ / min.

9. A near-infrared LED light source, characterized in that: The chip of the near-infrared LED light source is a blue LED chip, and the phosphor is the near-infrared phosphor according to any one of claims 1 to 3.

10. Use of the near-infrared phosphor according to any one of claims 1 to 3 in radiative cooling.

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