Dark green efficient near-infrared luminescent pigment as well as preparation method and application thereof

Abstract

The invention discloses a dark green efficient near-infrared luminescent pigment and a preparation method and application thereof, the chemical general formula of the near-infrared luminescent pigment is Li < 1 + nGa < 5-x-y > CryO < 8 + n / 2 >: xNi < 2 + >, 0 < = n < = 2.00, 0lt; x is less than or equal to 0.05, 0lt; and y < = 2.00. The near-infrared light-emitting pigment disclosed by the invention is high in light-emitting intensity, high in fluorescence conversion efficiency, good in temperature quenching characteristic, multiple in excitation wavelength selection and wide in emission wavelength range, an excitation band covers a spectral region from 300nm to 700nm, and an emission band covers a near-infrared region from 1000nm to 1700nm. The infrared light-emitting pigment can be used as a light conversion material of a blue light LED chip to realize a broadband near-infrared light-emitting light source. The pigment has high reflectivity in a range of 800-2500nm, and can be used as a cold pigment to be applied to a thermal radiation reflective coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of luminescent materials, and particularly relates to a deep green high-efficiency near-infrared luminescent pigment as well as a preparation method and application thereof. BACKGROUND

[0002] Near-infrared light (800-2500 nm) has a wide range of applications in food and drug detection, biological imaging, night vision, etc. In recent years, the demand for integrating near-infrared light sources into small portable devices such as mobile phones for real-time monitoring of the human body has put higher requirements on the efficiency and volume of near-infrared light. As one of the key components of near-infrared spectroscopy technology, traditional broadband near-infrared light sources (halogen tungsten lamps, xenon lamps, etc.) not only have low efficiency, large volume, and extremely high operating temperature, but also cannot meet the integration requirements. In addition, infrared LED chips have problems such as narrow emission spectrum, high cost, and poor spectral stability. The fluorescent conversion type LED using "visible light LED + broadband near-infrared luminescent material" has the characteristics of simple structure, high efficiency, low cost, and good spectral stability. Among them, the wider the emission spectrum of the near-infrared luminescent material, the more substances can be detected and analyzed by this technology; the higher the luminescent efficiency, the higher the light power of the final luminescent device, and the higher the signal-to-noise ratio of various near-infrared spectroscopy detection technologies, and the stronger the overall practicability. The existing technology, Cr 3+ -Ni 2+ activated near-infrared broadband emission fluorescent powder has an emission peak of 1330 nm and a quantum efficiency of only 48%. Therefore, it is of great significance to develop broadband near-infrared luminescent materials with good physical and chemical stability and high quantum efficiency for the practical application of fluorescent conversion type near-infrared LEDs.

[0003] At the same time, because near-infrared light has a photothermal effect, near-infrared light in solar radiation is usually referred to as a heat radiation source. In tropical and subtropical regions, solar radiation leads to heat accumulation inside buildings, while increasing the energy consumption of refrigeration equipment and greenhouse gas emissions. In order to overcome this challenge, passive cooling strategies have always been the main focus of building insulation, and building surface insulation systems are an important way to achieve passive energy-saving cooling design. Heat-reflecting coatings based on low-cost white or light-colored pigments (such as titanium dioxide and zinc oxide) are widely used in building and facility insulation surface coatings due to their strong reflection of solar radiation. However, these white or light-colored pigments have the disadvantages of light pollution, poor stain resistance, and lack of aesthetic appeal. Therefore, developing deep-colored pigments with high near-infrared reflectivity and adding them to coatings can prepare products with reflective insulation functions, and designing and creating new energy-saving and environmentally friendly near-infrared reflective pigments will have great value. SUMMARY

[0004] The present application aims to overcome the defects of low luminescent efficiency of the prior art near-infrared luminescent material suitable for commercial ultraviolet / blue / orange LED excitation and lack of deep color of near-infrared reflective pigments, and provides a deep green high-efficiency near-infrared luminescent pigment, a preparation method and application thereof. The near-infrared luminescent pigment has high luminescent quantum efficiency, good luminescent thermal stability, and a wide excitation and emission range, can be effectively excited by near-ultraviolet, violet or orange light, has strong absorption in the visible light range, and has high reflectivity in the near-infrared light range, can be used as a deep green pigment, and can be used as a "cool pigment" to block near-infrared radiation that generates heat, and is expected to produce great driving force in the fields of near-infrared light sources, spectral technology and heat reflective coatings.

[0005] To solve the above technical problems, the first aspect of the present application provides a near-infrared luminescent pigment, the chemical composition of the near-infrared luminescent pigment is Li 1+n Ga 5-x-y Cr y O 8+n / 2 :xNi 2+ , wherein: 0≤n≤2.00, 0

[0006] Specifically, the properties of the matrix and the synergistic effect of the doping elements have a great influence on the performance of the fluorescent powder. The near-infrared luminescent pigment provided by the present application takes Li 1+n Ga 5-y Cr y O8 as the matrix, and the doping ion Ni 2+ is the active ion, and the adjustment of Li + and Cr 3+ optimizes the fluorescent performance; the obtained broadband near-infrared fluorescent material can be effectively excited by near-ultraviolet, blue or orange light, produces fluorescent emission at 1240nm, and the internal quantum efficiency is greater than 100%.

[0007] Preferably, the value ranges of n, x and y are respectively: 0≤n≤0.50, 0

[0008] Further preferably, the value ranges of n, x and y are respectively: 0≤n≤0.50, 0

[0009] Specifically, the doping amount of Cr 3+ and Ni 2+ has a great influence on the synergistic effect of the two, and when the doping amount is controlled in the above range, the intensity of the 420nm blue excitation peak and the corresponding 1240nm near-infrared emission peak is further enhanced; and when x=0.005, y=1.00, the optimal value is reached.

[0010] The second aspect of the present application provides a preparation method of the near-infrared luminescent pigment, comprising the following steps:

[0011] (1) mixing a Li source, a Ga source, a Cr source, and a Ni source according to a stoichiometric ratio to obtain a mixture;

[0012] (2) calcining the mixture and grinding to obtain the near-infrared luminescent pigment.

[0013] Specifically, in the preparation of the near-infrared luminescent pigment of the present application, the raw materials are first mixed uniformly, and then the raw materials are reacted by calcination to obtain a stable near-infrared luminescent pigment. The preparation method is simple, the synthesis time is short, the equipment cost is low, and there is no pollution, which is suitable for popularization and application.

[0014] Preferably, in step (1), the stoichiometric ratio is consistent with the stoichiometric ratio in the chemical formula.

[0015] It should be noted that the conventional Li source, Ga source, Cr source, and Ni source in the art can be applied to the present application.

[0016] Preferably, in step (1), the Li source is at least one of the elemental substance, oxide, chloride, sulfide, or salt (such as carbonate, sulfate, phosphate, or nitrate) of Li; further preferably, the Li source is Li2O and / or Li2CO3.

[0017] Preferably, in step (1), the Ga source is at least one of the elemental substance, oxide, chloride, sulfide, or salt (such as carbonate, sulfate, phosphate, or nitrate) of Ga; further preferably, the Ga source is Ga2O3 and / or GaCl3.

[0018] Preferably, in step (1), the Cr source is at least one of the elemental substance, oxide, chloride, sulfide, or salt (such as carbonate, sulfate, phosphate, or nitrate) of Cr; further preferably, the Cr source is Cr2O3 and / or Cr(NO3)3.

[0019] Preferably, in step (1), the Ni source is at least one of the elemental substance, oxide, chloride, sulfide, or salt (such as carbonate, sulfate, phosphate, or nitrate) of Ni; further preferably, the Ni source is NiO and / or Ni(OH)2.

[0020] Preferably, in step (1), the mixing is performed by grinding in a solvent.

[0021] Preferably, the solvent is selected from at least one of ethanol, water, and methanol.

[0022] Preferably, in step (2), the temperature of the calcination is 1000-1600℃.

[0023] Preferably, in step (2), the time of the calcination is 2-20 hours.

[0024] Preferably, in step (2), the calcination is carried out under an air atmosphere or a nitrogen atmosphere; further preferably, the calcination atmosphere is an air atmosphere.

[0025] Preferably, in step (2), the time of the grinding is 5-120 min; further preferably, the time of the grinding is 15-30 min.

[0026] The third aspect of the present application provides a near-infrared light source, which comprises the above-mentioned near-infrared luminescent pigment.

[0027] The fourth aspect of the present application provides a heat-reflecting coating, which comprises the above-mentioned near-infrared luminescent pigment.

[0028] The fifth aspect of the present application provides the use of the above-mentioned near-infrared luminescent pigment in luminescent ceramics, glass, coating or plastic.

[0029] The above technical solutions of the present application have at least the following technical effects or advantages relative to the prior art:

[0030] (1) The present application uses Li 1+n Ga 5-y Cr y O8 as a matrix, dopes ion Ni 2+ as an activating ion, adjusts Li + and Cr 3+ to optimize the fluorescent performance, so that the obtained near-infrared luminescent pigment has high luminous intensity, high quantum efficiency, good temperature quenching characteristics, multiple excitation wavelength selection and wide emission wavelength range, the excitation band covers the spectral region from 300 nm to 700 nm, and the emission band covers the near-infrared region from 1000 nm to 1700 nm. The infrared luminescent pigment can be used as a light conversion material for a blue LED chip to realize a broadband near-infrared light source.

[0031] (2) The near-infrared luminescent pigment of the present application has a light absorption rate close to 90% in the range of 400 nm to 800 nm and a light reflectivity close to 95% in the range of 1000 nm to 2000 nm, which not only can be applied to dark green pigments, but also can be used as a "cool pigment" to block near-infrared radiation that generates heat effects, and can be widely applied to luminescent ceramics, glass, coating or plastic, avoiding the disadvantages of other infrared light acquisition methods.

[0032] (3) The preparation method of the near-infrared luminescent pigment of the present application is simple in process and low in synthesis cost, and is convenient for large-scale industrial production. Attached Figure Description

[0033] Figure 1 XRD patterns of the near-infrared luminescent pigments prepared in Examples 1-6;

[0034] Figure 2 The fluorescence emission spectra of the near-infrared luminescent pigments prepared in Example 3 and Example 1 under 420 nm excitation;

[0035] Figure 3 The excitation spectrum of the near-infrared luminescent pigments prepared in Example 3 and Example 1 was monitored when they emitted at 1240 nm.

[0036] Figure 4 The near-infrared quantum efficiency spectrum of the near-infrared luminescent pigment prepared in Example 3;

[0037] Figure 5 The graph shows the relationship between the near-infrared fluorescence spectrum of the near-infrared luminescent pigment prepared in Example 3 and temperature.

[0038] Figure 6 The absorption spectra of the near-infrared luminescent pigments prepared in Example 3 and Comparative Example 1;

[0039] Figure 7 A physical image of a coating made using the near-infrared luminescent pigment prepared in Example 3. Detailed Implementation

[0040] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0041] Example 1

[0042] A near-infrared luminescent pigment with the chemical formula: Li3Ga 3.99 CrNi 0.01 O9, i.e., Li3Ga 3.99 CrO9:0.01Ni. The preparation method of this near-infrared luminescent pigment includes the following steps:

[0043] (1) Based on the above-mentioned near-infrared luminescent pigment composition design, the matrix is ​​Li3Ga 3.99 CrO9, doped with Ni ions 2+doped with 1.0 mol% of Ni 3.99 CrNi 0.01 O9stoichiometric ratio of Li2CO3, Ga2O3, NiO and Cr2O3, the molar ratio of each element is Li:Ga:Ni:Cr:O=3:3.99:0.01:1:9; then each raw material is placed in an agate mortar and ground for 5 min (the grinding medium is anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol is 1 g:3 mL) to fully mix each raw material to obtain a mixture;

[0044] (2) The mixture prepared in step (1) is moved to a corundum crucible, covered and placed in a high-temperature reaction furnace for calcination at 1600°C for 2 hours; naturally cooled to room temperature, and the sample is taken out and ground for 20 min to obtain the near-infrared luminescent pigment Li 3.99 CrO9:0.01Ni.

[0045] Example 2

[0046] A near-infrared luminescent pigment with the chemical formula: Li 1.50 Ga 3.49 Cr 1.50 Ni 0.01 O 8.25 , i.e. Li 1.50 Ga 3.49 Cr 1.50 O 8.25 :0.01Ni. The preparation method of the near-infrared luminescent pigment comprises the following steps:

[0047] (1) According to the composition design of the above-mentioned near-infrared luminescent pigment, the substrate is Li 1.50 Ga 3.49 Cr 1.50 O 8.25 , doped with 1.0 mol% of Ni 2+ doped with 1.0 mol% of Ni 1.50 Ga 3.49 Cr 1.50 Ni 0.01 O 8.25 stoichiometric ratio of Li2CO3, Ga2O3, NiO and Cr2O3, the molar ratio of each element is Li:Ga:Ni:Cr:O=1.50:3.49:0.01:1.5:8.25; then each raw material is placed in an agate mortar and ground for 2 hours (the grinding medium is anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol is 1 g:3 mL) to fully mix each raw material to obtain a mixture;

[0048] (2) Transfer the mixture obtained in step (1) into a corundum crucible, cover it, and place it in a high-temperature reaction furnace for calcination at 1000°C for 20 hours; allow it to cool naturally to room temperature, remove the sample, and grind it for 15 minutes to obtain the near-infrared luminescent pigment Li of this embodiment. 1.50 Ga 3.49 Cr 1.50 O 8.25 0.01Ni.

[0049] Example 3

[0050] A near-infrared luminescent pigment with the chemical formula: Li 1.10 Ga 3.99 CrNi 0.01 O 8.05 Li 1.10 Ga 3.99 CrO 8.05 0.01Ni. The preparation method of this near-infrared luminescent pigment includes the following steps:

[0051] (1) Based on the above composition design of near-infrared luminescent pigments, the matrix is ​​Li 1.10 Ga 3.99 CrO 8.05 Ni doped ions 2+ The doping amount is 1.0 mol%, according to the chemical formula Li 1.10 Ga 3.99 CrNi 0.01 O 8.05 Lithium carbonate (Li₂CO₃), gallium oxide (Ga₂O₃), nickel oxide (NiO), and chromium oxide (Cr₂O₃) were weighed out in stoichiometric proportions, with a molar ratio of Li:Ga:Ni:Cr:O = 1.10:3.99:0.01:1:8.05. The raw materials were then placed in an agate mortar and ground for 30 minutes (the grinding medium was anhydrous ethanol, and the mass-to-volume ratio of the material to anhydrous ethanol was 1 g:3 mL) to ensure thorough mixing and obtain a mixture.

[0052] (2) Transfer the mixture obtained in step (1) into a corundum crucible, cover it, and place it in a high-temperature reaction furnace for calcination at 1200°C for 6 hours; allow it to cool naturally to room temperature, remove the sample, and grind it for 30 minutes to obtain the near-infrared luminescent pigment Li of this embodiment. 1.10 Ga 3.99 CrO 8.05 0.01Ni.

[0053] Example 4

[0054] A near-infrared luminescent pigment with the chemical formula: Li 1.30 Ga 4.49 Cr 0.50Ni 0.01 O 8.15 , i.e. Li 1.30 Ga 4.49 Cr 0.50 O 8.15 :0.01Ni. The preparation method of the near-infrared luminescent pigment comprises the following steps:

[0055] (1) According to the composition design of the above-mentioned near-infrared luminescent pigment, the substrate is Li 1.30 Ga 4.49 Cr 0.50 O 8.15 , the doping amount of the doping ion Ni 2+ is 1.0 mol%, lithium carbonate (Li2CO3), gallium oxide (Ga2O3), nickel oxide (NiO) and chromium oxide (Cr2O3) are weighed according to the stoichiometric ratio of the chemical formula Li 1.30 Ga 4.49 Cr 0.50 Ni 0.01 O 8.15 , the molar ratio of each element is Li:Ga:Ni:Cr:O = 1.30:4.49:0.01:0.5:8.15; then each raw material is placed in an agate mortar and ground for 30 min (the grinding medium is anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol is 1g:3mL), so that each raw material is fully mixed to obtain a mixture;

[0056] (2) The mixture prepared in step (1) is moved to a corundum crucible, covered and placed in a high-temperature reaction furnace for calcination at 1400°C for 5 hours; naturally cooled to room temperature, and the sample is taken out and ground for 60 min to obtain the near-infrared luminescent pigment Li 1.30 Ga 4.49 Cr 0.50 O 8.15 :0.01Ni of the present embodiment.

[0057] Example 5

[0058] A near-infrared luminescent pigment has a chemical formula: Li 1.50 Ga 4.495 Cr 0.50 Ni 0.005 O 8.25 , i.e. Li 1.50 Ga 4.495 Cr 0.50 O 8.25 :0.005Ni. The preparation method of the near-infrared luminescent pigment comprises the following steps:

[0059] (1) According to the composition design of the above-mentioned near-infrared luminescent pigment, the substrate is Li 1.50 Ga 4.495 Cr0.50 O 8.25 2+ 1.50 Ga 4.495 Cr 0.50 Ni 0.005 O 8.25 Li2CO3, Ga2O3, NiO and Cr2O3 were weighed according to the stoichiometric ratio, and the molar ratio of each element was Li:Ga:Ni:Cr:O = 1.50:4.495:0.005:0.5:8.25; then each raw material was placed in an agate mortar and ground for 15 min (the grinding medium was anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol was 1 g:3 mL), so that each raw material was fully mixed to obtain a mixture;

[0060] (2) The mixture prepared in step (1) was moved to a corundum crucible, covered and placed in a high-temperature reaction furnace for calcination at 1500°C for 4 hours; after natural cooling to room temperature, the sample was taken out and ground for 15 min to obtain the near-infrared luminescent pigment LiGa 1.50 Ga 4.495 Cr 0.50 O 8.25 :0.005Ni.

[0061] Example 6

[0062] A near-infrared luminescent pigment with a chemical formula of LiGa 3.495 Cr 1.50 Ni 0.005 O8, i.e. LiGa 3.495 Cr 1.50 O8:0.005Ni. The preparation method of the near-infrared luminescent pigment comprises the following steps:

[0063] (1) According to the composition design of the above-mentioned near-infrared luminescent pigment, the substrate is LiGa 3.495 Cr 1.50 O8, and the doping amount of the doping ion Ni 2+ is 0.5 mol%, according to the chemical formula LiGa 3.495 Cr 1.50 Ni 0.005 ​​The stoichiometric ratio of Li2CO3, Ga2O3, NiO and Cr2O3 is Li:Ga:Ni:Cr:O = 1:3.495:0.005:1.5:8, and then the raw materials are placed in an agate mortar and ground for 15 min (the grinding medium is anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol is 1 g:3 mL) to fully mix the raw materials to obtain a mixture;

[0064] (2) The mixture prepared in step (1) is moved to a corundum crucible, covered and placed in a high-temperature reaction furnace for calcination at 1300°C for 12 hours; naturally cooled to room temperature, and then the sample is taken out and ground for 40 min to obtain the near-infrared luminescent pigment LiGa 3.495 Cr 1.50 O8:0.005Ni.

[0065] Comparative Example 1

[0066] A near-infrared luminescent pigment with a chemical formula of LiGa 4.995 Ni 0.005 O8, i.e., LiGa 4.995 O8:0.005Ni. The preparation method of the near-infrared luminescent pigment comprises the following steps:

[0067] (1) According to the composition design of the above-mentioned near-infrared luminescent pigment, the substrate is LiGa5O8, and the doping ion Ni 2+ is doped at a doping amount of 0.5 mol%, according to the chemical formula LiGa 4.995 Ni 0.005 O8. The stoichiometric ratio of Li2CO3, Ga2O3 and NiO is Li:Ga:Ni:O = 1:4.995:0.005:8, and then the raw materials are placed in an agate mortar and ground for 15 min (the grinding medium is anhydrous ethanol, and the mass-volume ratio of the material to anhydrous ethanol is 1 g:3 mL) to fully mix the raw materials to obtain a mixture;

[0068] (2) The mixture prepared in step (1) is moved to a corundum crucible, covered and placed in a high-temperature reaction furnace for calcination at 1300°C for 6 hours; naturally cooled to room temperature, and then the sample is taken out and ground for 30 min to obtain the near-infrared luminescent pigment LiGa 4.995 O8:0.005Ni.

[0069] Performance test

[0070] 1. Component analysis

[0071] The near-infrared luminescent pigments prepared in Examples 1-6 were subjected to XRD tests using an X-ray diffractometer (model D / MAX 2200VPC) manufactured by Rigaku Corporation, Japan. The results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the X-ray powder diffraction patterns of the near-infrared luminescent pigments prepared in Examples 1-6 are consistent with the ICSD LiGa5O8 standard card (PDF 38-1371), indicating that no other phases or impurities were introduced.

[0072] 2. Luminous intensity

[0073] The emission spectra of the near-infrared luminescent pigments prepared in Example 3 and Example 1 under 420 nm excitation were tested using an Edinburgh FLS1000 steady-state transient fluorescence spectrometer with a 500W xenon lamp as the excitation source. The results are as follows: Figure 2 As shown. By Figure 2 It can be seen that, under 420nm excitation, both near-infrared luminescent pigments can emit near-infrared light centered around 1240nm, but the Cr prepared in Example 3... 3+ / Ni 2+ The co-doped infrared luminescent pigment has a significantly stronger luminescence intensity than Comparative Example 1, and its emission band covers the near-infrared region from 1000 nm to 1700 nm.

[0074] 3. Excitation spectral intensity

[0075] Figure 3 The excitation spectra of the near-infrared luminescent pigments prepared in Example 3 and Example 1 at 1240 nm emission were monitored by... Figure 3 It can be seen that when monitoring near-infrared light emission at 1240nm, the Cr prepared in Example 3... 3+ / Ni 2+ The excitation spectral intensity of the co-doped infrared luminescent pigment sample was significantly stronger than that of Comparative Example 1, and the excitation peaks at three different positions showed different degrees of shift and broadening.

[0076] Meanwhile, the near-infrared luminescent pigments prepared in Examples 1-2 and Examples 4-6 also showed different degrees of shift and broadening in their excitation peaks when monitoring near-infrared light emission at 1240 nm.

[0077] 4. Quantum efficiency

[0078] Figure 4 The near-infrared quantum efficiency spectrum of the near-infrared luminescent pigment prepared in Example 3, with an excitation wavelength of 420 nm, is obtained from... Figure 4 It can be seen that the quantum efficiency of this near-infrared luminescent pigment is 120%.

[0079] 5. Thermal stability

[0080] Figure 5 This is a graph showing the relationship between the near-infrared fluorescence spectrum of the near-infrared luminescent pigment prepared in Example 3 and temperature. Figure 5 It can be seen that the near-infrared luminescent pigment retains 90.8% of its fluorescence intensity at room temperature at 380K and 56.3% at 460K, which is sufficient to demonstrate its excellent thermal stability.

[0081] 6. Reflectivity

[0082] Figure 6 The absorption spectra of the near-infrared luminescent pigments prepared in Example 3 and Comparative Example 1 are obtained from... Figure 6 It can be seen that the near-infrared luminescent pigment Li prepared in Example 3 1.50 Ga 3.995 CrO 8.5 0.005Ni relative to the near-infrared luminescent pigment LiGa prepared in Comparative Example 1 4.995 O8:0.005Ni exhibits significantly enhanced absorption in the visible light range and maintains high reflectivity in the near-infrared range.

[0083] 7. Color

[0084] The chromaticity coordinates of the near-infrared luminescent pigments prepared in Examples 1-3 were tested, and the results are shown in Table 1, where: L represents lightness, a* represents the range from green to red, and b* represents the range from blue to yellow.

[0085] Table 1:

[0086]

[0087]

[0088] As shown in Table 1, the near-infrared luminescent pigment prepared by this invention is dark green in the visible light band, with a brightness value of 50-55.

[0089] Meanwhile, the near-infrared luminescent pigment prepared in Example 3 was used to prepare a coating. The preparation process was as follows: the near-infrared luminescent pigment and polydimethylsiloxane were mixed at a mass ratio of 1:1 to obtain a mixture; then, the mixture was applied to the surface of a glass plate and heated at 70°C for 1 hour to obtain the coating. The actual product of this coating is shown below. Figure 7 As shown, it appears green.

[0090] In summary, the near-infrared luminescent pigment prepared by this invention is deep green in color and possesses both high efficiency in near-infrared emission and high near-infrared reflectivity. The pigment exhibits a high quantum efficiency of 120% under 420nm light source excitation, making it suitable as a high-efficiency near-infrared light source material. Furthermore, the pigment exhibits high reflectivity in the 800-2500nm range, enabling its application as a "cold pigment" in thermal radiation reflective coatings. Therefore, the near-infrared luminescent pigment prepared by this invention has broad application prospects in both inorganic luminescent materials and inorganic pigment technologies.

[0091] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A near-infrared luminescent pigment, characterized in that, The chemical formula of the near-infrared luminescent pigment is Li. 1+n Ga 5-x- y Cr y O 8+n / 2 :xNi 2+ Where: 0 ≤ n ≤ 2.00, 0 <x≤0.05,0<y≤2.00。 2. The near-infrared luminescent pigment according to claim 1, characterized in that, The ranges of n, x, and y are respectively: 0 ≤ n ≤ 0.50, 0 <x≤0.01,0.50<y≤1.50。 3. A method for preparing a near-infrared luminescent pigment as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Mix the Li source, Ga source, Cr source and Ni source in stoichiometric ratio to obtain a mixture; (2) The mixture is calcined and then ground to obtain the near-infrared luminescent pigment.

4. The method for preparing the near-infrared luminescent pigment according to claim 3, characterized in that, In step (1), the stoichiometric ratio is consistent with the stoichiometric ratio in the general chemical formula.

5. The method for preparing the near-infrared luminescent pigment according to claim 3, characterized in that, In step (1), the Li source is at least one of elemental Li, oxides, chlorides, sulfides, or salts; And / or, the Ga source is at least one of elemental Ga, oxide, chloride, sulfide or salt; And / or, the Cr source is at least one of elemental Cr, oxide, chloride, sulfide or salt; And / or, the Ni source is at least one of elemental Ni, oxide, chloride, sulfide, or salt.

6. The method for preparing the near-infrared luminescent pigment according to claim 3, characterized in that, In step (1), the mixing method is grinding in a solvent; and / or, the solvent is selected from at least one of ethanol, water, and methanol.

7. The method for preparing the near-infrared luminescent pigment according to claim 3, characterized in that, In step (2), the calcination temperature is 1000-1600℃; and / or the calcination time is 2-20 hours.

8. A near-infrared light source, characterized in that, The near-infrared light source includes the near-infrared luminescent pigment as described in claim 1 or 2.

9. A heat-reflective coating, characterized in that, The heat-reflective coating includes the near-infrared luminescent pigment as described in claim 1 or 2.

10. The use of the near-infrared luminescent pigment according to claim 1 or 2 in luminescent ceramics, glass, coatings or plastics.

Images