Ni < 2 + >-doped double-perovskite-based broadband tunable near-infrared fluorescent powder as well as preparation method and application thereof

Abstract

The invention relates to Ni < 2 + >-doped double-perovskite-based broadband tunable near-infrared fluorescent powder as well as a preparation method and application thereof, and belongs to the technical field of inorganic luminescent materials. The chemical formula of the near-infrared fluorescent powder is (Sr1-zCaz) 2MgWO6: xNi < 2 + >, wherein x is greater than or equal to 0.005 and less than or equal to 0.025, and z is greater than or equal to 0 and less than or equal to 1.0. The Ni < 2 + >-doped double-perovskite-based broadband tunable near-infrared fluorescent powder disclosed by the invention is high in luminance, simple in preparation process, good in reproducibility, low in synthesis raw material cost and suitable for large-scale production; the NIR pc-LED device prepared from the near-infrared fluorescent powder is low in cost, high in luminous efficiency and high in penetrability, and the application of the NIR pc-LED device in night vision, vein imaging and nondestructive testing is promoted.

Description

Technical Field

[0001] This invention relates to a Ni 2+ The doped double perovskite-based broadband tunable near-infrared phosphor, its preparation method and application, belong to the field of inorganic luminescent materials technology. Background Technology

[0002] In recent years, the immense potential of broadband near-infrared light sources in various fields such as optical communication, food inspection, night vision, and biomedical imaging has attracted widespread attention from researchers both domestically and internationally regarding the design of near-infrared fluorescent materials. Compared to traditional broadband near-infrared sources like halogen lamps and tungsten halogen lamps, and supercontinuum lasers, emerging near-infrared II (NIR-II) pc-LED light sources offer significant advantages, including smaller device size, lower cost, longer lifespan, higher efficiency, and user-friendly design. Therefore, developing various high-performance broadband near-infrared phosphors is of paramount importance for packaging high-performance NIR pc-LED devices. Furthermore, considering the differences in application characteristics of near-infrared light across different wavelengths, such as differences in penetration ability, imaging resolution, and signal-to-noise ratio, the interaction between photons and tissue is significantly reduced in the NIR-II window compared to visible light and NIR-I. This results in greater penetration depth and higher imaging resolution for NIR-II fluorescence imaging. Moreover, this interaction decreases inversely with increasing wavenumber, further enhancing light penetration and improving imaging resolution. Therefore, there is an urgent need to develop infrared wavelengths with wider and longer ranges to meet application requirements. Summary of the Invention

[0003] This invention provides a Ni 2+ Doped double perovskite-based broadband tunable near-infrared phosphors, their preparation methods, and applications are presented to address the problems existing in the prior art as described above.

[0004] The technical solution provided by this invention is as follows: One of the objectives of this invention is to provide a Ni 2+ The doped double perovskite-based broadband tunable near-infrared phosphor has the following chemical formula: (Sr 1-z Ca z )2MgWO6:xNi 2+ , where 0.005≤x≤0.025, 0≤z≤1.0.

[0005] Furthermore, when x = 0.005, 0.01, 0.015, 0.02, or 0.025 and z = 0 in the chemical formula, the emission wavelength range of the infrared phosphor is 1000-1700 nm, and the full width at half maximum (FWHM) is 200-250 nm. Ni 2+ It is the luminescent center.

[0006] Furthermore, when x = 0.015 and z = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 in the chemical formula, the emission wavelength range of the infrared phosphor is 1000-1750 nm, and the full width at half maximum (FWHM) is 200-350 nm. Ni 2+ It is the luminescent center.

[0007] The second objective of this invention is to provide the aforementioned Ni 2+ A method for preparing doped double perovskite-based broadband tunable near-infrared phosphors includes the following steps: 1) Accurately weigh the required raw materials according to the stoichiometric ratio of the chemical formula; 2) Transfer the weighed raw materials to a mortar and grind with anhydrous ethanol to obtain a slurry-like mixture. Grind for 25-35 minutes until the anhydrous ethanol is completely evaporated to obtain a powdery, uniform mixture. 3) Place the uniform mixture obtained in step 2) into a muffle furnace, pre-calcine it in an air atmosphere, then calcine it at a high temperature, and finally obtain the calcined product. 4) After naturally cooling to room temperature, the calcined product is removed from the muffle furnace, ground, and sieved to finally obtain the Ni. 2+ Doped double perovskite-based broadband tunable near-infrared phosphor.

[0008] Further, in step 1), the raw materials are SrCO3, CaCO3, MgO, WO3 and NiO.

[0009] Further, in step 2), the amount of anhydrous ethanol added is 2-4 ml of anhydrous ethanol per gram of mixed raw materials.

[0010] Further, in step 3), the pre-calcination temperature is 850-950℃ and the calcination time is 2-4h; the high-temperature calcination temperature is 1250-1350℃ and the calcination time is 5-7h. Further, in step 4), the grinding time is 5-15 minutes, and the sieving is done through a 100-300 mesh sieve.

[0011] A third objective of this invention is to provide a NIR pc-LED, comprising the Ni as described above. 2+ Doped double perovskite-based broadband tunable near-infrared phosphor.

[0012] The fourth objective of this invention is to provide the application of the above-mentioned NIR pc-LED in night vision, medical imaging and non-destructive testing.

[0013] The fifth objective of this invention is to provide a method for preparing the aforementioned NIR pc-LED, comprising the following steps: preparing the aforementioned Ni... 2+Doped double perovskite-based broadband tunable near-infrared phosphors are mixed with AB potting compound at a mass ratio of 1:0.5:0.5 to obtain a powder slurry. The obtained powder slurry is then applied to a commercially available InGaN violet LED chip by dispensing, and then dried and cured at 90-120℃ to obtain a NIR pc-LED.

[0014] The technical solution provided by this invention has the following advantages compared with the prior art: 1. This invention prepares Ni using a high-temperature solid-state method. 2+ Doped double perovskite-based Sr2MgWO6:xNi 2+ A broadband near-infrared phosphor was developed, achieving broadband long-wavelength emission at 1400 nm with a full width at half maximum (FWHM) of 231 nm. Furthermore, based on a cation substitution strategy, Ca... 2+ Replace Sr 2+ A series of Ni were prepared 2+ Doped double perovskite-based (Sr 1-z Ca z )2MgWO6:xNi 2+ A spectrally tunable broadband near-infrared phosphor achieves a redshift of the emission peak position from 1400 nm to 1485 nm, and extends the full width at half maximum (FWHM) from 231 nm to 323 nm; substituted ion Ca 2+ With the increase of Ni content, 2+ The decrease in the average bond length of Mg / Ni-O in the doped Sr2MgWO6 perovskite structure leads to increased distortion of the [Mg / NiO6] octahedron in the sample, resulting in highly asymmetric Ni... 2+ The increased number of bits leads to a larger Stokes shift, resulting in longer wavelengths and wider bands of emission, thus achieving the desired goal of near-infrared broadband long-wavelength emission.

[0015] 2. The Ni provided by this invention 2+ The doped double perovskite-based broadband tunable near-infrared phosphor has high luminescence brightness, simple preparation process, good reproducibility, low raw material cost, and is suitable for large-scale production.

[0016] 3. The Ni provided by this invention 2+ Doped Ca2MgWO6:xNi 2+ The near-infrared phosphor achieves broadband and NIR-II region long-wave emission. It can be efficiently excited by InGaN violet LED chips and converted into near-infrared emission of 1000-1750nm, with a peak emission of 1485nm and a full width at half maximum (FWHM) of 323nm.

[0017] 4. The Ni provided by this invention 2+NIR pc-LED devices fabricated with doped double perovskite-based broadband tunable near-infrared phosphors are low in cost, high in luminous efficiency, and strong in penetration, which promotes their application in night vision, vein imaging, and non-destructive testing. Attached Figure Description

[0018] Figure 1 The X-ray diffraction patterns are of the near-infrared phosphors prepared in Examples 1-5 of this invention.

[0019] Figure 2 The emission spectra of the near-infrared phosphors prepared in Examples 1-5 of this invention are shown.

[0020] Figure 3 The excitation and emission spectra of the near-infrared phosphor prepared in Example 3 of this invention are shown.

[0021] Figure 4 The lifetime decay curves of the near-infrared phosphors prepared in Examples 1-5 of this invention are shown.

[0022] Figure 5 The X-ray diffraction patterns are those of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention.

[0023] Figure 6 The images show the morphology of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention.

[0024] Figure 7 The normalized excitation spectra of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention are shown.

[0025] Figure 8 The normalized emission spectra of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention are shown.

[0026] Figure 9 The graph shows the emission peak position and full width at half maximum (FWHM) variation of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention.

[0027] Figure 10 The diagram shows the variation of the average bond length of the Mg-O bond in the tunable near-infrared phosphor structure prepared in Examples 6-15 of this invention.

[0028] Figure 11 The torsion index diagram of the [MgO6] octahedron in the tunable near-infrared phosphor structure prepared in Examples 6-15 of this invention is shown.

[0029] Figure 12 The fluorescence lifetime diagrams are for the tunable near-infrared phosphors prepared in Examples 6-15 of this invention.

[0030] Figure 13The left and right sections are diagrams of NIR pc-LED devices encapsulated with tunable near-infrared phosphors, prepared in Application Example 1 using Example 15 and Application Example 2 using Example 10, respectively.

[0031] Figure 14 This invention provides an example of the application of the tunable near-infrared phosphor-encapsulated NIRpc-LED device prepared in Example 15 for night vision.

[0032] Figure 15 This invention provides an example of the application of the tunable near-infrared phosphor-encapsulated NIRpc-LED device prepared in Example 15 in vein imaging.

[0033] Figure 16 This invention provides an example of the application of the tunable near-infrared phosphor-encapsulated NIRpc-LED device prepared in Example 15 in the non-destructive testing of carbon sketch marks on the underside of an oil painting.

[0034] Figure 17 This invention provides an application example 2 of the tunable near-infrared phosphor-encapsulated NIRpc-LED device prepared in Example 10 for the detection of traces in watercolor painting and carbon sketching. Detailed Implementation

[0035] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0036] The AB potting compound used in this example is a transparent epoxy resin potting compound. Component A is the epoxy resin matrix, and component B is the curing agent. It was purchased from Delang Adhesives Co., Ltd., model number D-600AB-TM.

[0037] Example 1 In this embodiment, Ni 2+ A doped double perovskite-based broadband tunable near-infrared phosphor with the chemical formula Sr₂MgWO₆:0.005Ni 2+ The specific preparation steps are as follows: (1) SrCO3, MgO, WO3 and NiO are weighed precisely according to the stoichiometric ratio of the above chemical formulas to obtain a mixture. 3 ml of anhydrous ethanol is added to each gram of the mixed raw material and ground to obtain a mud-like mixture. The mixture is ground for 30 minutes until the anhydrous ethanol is completely evaporated to obtain a powdery uniform mixture. (2) The uniform mixture obtained in step (1) is placed into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900℃ for 3 hours, then calcined at 1300℃ for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes and passed through a 200-mesh sieve to obtain near-infrared phosphor.

[0038] Example 2 In this embodiment, Ni 2+ A doped double perovskite-based broadband tunable near-infrared phosphor with the chemical formula Sr₂MgWO₆:0.01Ni 2+ The specific preparation steps are as follows: (1) SrCO3, MgO, WO3 and NiO are weighed precisely according to the stoichiometric ratio of the above chemical formulas to obtain a mixture. 3 ml of anhydrous ethanol is added to each gram of the mixed raw material and ground to obtain a mud-like mixture. The mixture is ground for 30 minutes until the anhydrous ethanol is completely evaporated to obtain a powdery uniform mixture. (2) The uniform mixture obtained in step (1) is placed into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900℃ for 3 hours, then calcined at 1300℃ for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes and passed through a 200-mesh sieve to obtain near-infrared phosphor.

[0039] Examples 3-5 Ni in Examples 3-5 2+ The doped double perovskite-based broadband tunable near-infrared phosphors have the following chemical formulas: Sr₂MgWO₆:0.015Ni 2+ Sr2MgWO6:0.02Ni 2+ Sr2MgWO6:0.025Ni 2+ .

[0040] The specific preparation steps are as follows: (1) SrCO3, MgO, WO3 and NiO were weighed precisely according to the stoichiometric ratio of the above chemical formulas to obtain a mixture. 3 ml of anhydrous ethanol was added to each gram of the mixed raw material and ground to obtain a mud-like mixture. The mixture was ground for 30 minutes until the anhydrous ethanol was completely evaporated to obtain a uniform powder mixture. (2) The uniform mixture obtained in step (1) is loaded into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900°C for 3 hours, then calcined at 1300°C for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes. After passing through a 200-mesh sieve, the corresponding near-infrared phosphor is obtained.

[0041] Figure 1 These are X-ray diffraction patterns of the near-infrared phosphors prepared in Examples 1-5 of this invention. Figure 1 The diffraction peaks of the synthesized samples in Examples 1-5 of this invention all match the diffraction peaks in the standard card of Sr2MgWO6, and no other impurity peaks appear, indicating that Ni doping... 2+ The subsequent synthesis did not affect the matrix crystal structure, and the samples synthesized in Examples 1-5 of this invention are pure phases.

[0042] Figure 2 These are the emission spectra of the near-infrared phosphors prepared in Examples 1-5 of this invention. Figure 2 It can be seen that different concentrations of Ni 2+ Doped Sr2MgWO6:xNi 2+ (0.005≤x≤0.025) Near-infrared phosphors all exhibited broadband NIR-II emission at a wavelength of 1400 nm under 320 nm monitoring, and the peak shape of the spectrum did not change significantly; the luminescence intensity increased with Ni 2+ As the ion doping concentration increased from 0.005 to 0.025, the luminescence intensity first increased and then decreased, reaching a peak at 0.015, followed by a decrease when the Ni concentration was further increased. 2+ When the ion doping concentration was reduced to 0.025, the luminescence intensity of the sample decreased significantly, which was due to the concentration quenching effect.

[0043] Figure 3 The Sr2MgWO6:0.015Ni prepared in Example 3, which achieves optimal emission in Examples 1-5 of this invention, is an example of this invention. 2+ Excitation and emission spectra of near-infrared phosphors. Sr₂MgWO₆:₀.₁₅Ni was detected under 320 nm UV excitation. 2+ The near-infrared phosphor's emission spectrum covers the range from 1000 nm to 1700 nm, with a full width at half maximum (FWHM) of 231 nm and a maximum peak value at 1400 nm. This is attributed to Ni. 2+ of 3 T2( 3 F)→ 3 A2( 3 The spin-allowed transition of F). At a monitoring wavelength of 1400 nm, two distinct excitation peaks are observed at its excitation wavelength: a strong excitation peak at 320 nm and a weak excitation peak at 690 nm. These two excitation peaks are attributed to Ni. 2+ of 3 A2( 3 F)→ 3 T1( 3 P) and 3 A2( 3 F)→ 3 T1( 3 The spin-allowed transition of F) and the peak at 420 nm are attributed to 3 A2( 3 F)→ 1 T2( 1 Spin forbidden transition of D).

[0044] Figure 4The lifetime decay curves of the near-infrared phosphors prepared in Examples 1-5 of this invention are shown. Under 320 nm excitation and 1400 nm monitoring, the fluorescence lifetime of the near-infrared phosphors prepared in Examples 1-5 decreases with Ni. 2+ The concentration increased, decreasing from 0.414 ms to 0.402 ms, indicating that concentration quenching occurred.

[0045] Example 6 In this embodiment, Ni 2+ Doped double perovskite-based broadband tunable near-infrared phosphor, with the chemical formula (Sr 1-z Ca z )2MgWO6:xNi 2+ The value of z represents Ca. 2+ For the original Sr2MgWO6 matrix, Sr 2+ In this embodiment, x is taken as Ni from the optimal emission embodiment 3 among the embodiments 1-5 described above. 2+ The doping concentration is 0.015, and z is 0.1. The specific preparation steps are as follows: (1) Mix the raw materials SrCO3, CaCO3, MgO, WO3, and NiO according to the chemical formula Sr 1.8 Ca 0.2 MgWO6:0.015Ni 2+ The stoichiometric ratio was accurately weighed to obtain a mixture, and 3 ml of anhydrous ethanol was added to each gram of the mixed raw material and ground to obtain a slurry-like mixture. The mixture was ground for 30 minutes until the anhydrous ethanol was completely evaporated, and a uniform powdery mixture was obtained. (2) The uniform mixture obtained in step (1) is placed into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900℃ for 3 hours, then calcined at 1300℃ for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes and passed through a 200-mesh sieve to obtain near-infrared phosphor.

[0046] Example 7 In this embodiment, Ni 2+ Doped double perovskite-based broadband tunable near-infrared phosphor, with the chemical formula (Sr 1-z Ca z )2MgWO6:xNi 2+ The value of z represents Ca. 2+ For the original Sr2MgWO6 matrix, Sr 2+ In this embodiment, x is taken as Ni from the optimal emission embodiment 3 among the embodiments 1-5 described above. 2+ The doping concentration is 0.015, and z is 0.2. The specific preparation steps are as follows: (1) Mix the raw materials SrCO3, CaCO3, MgO, WO3, and NiO according to the chemical formula Sr1.6 Ca 0.4 MgWO6:0.015Ni 2+ The stoichiometric ratio was accurately weighed to obtain a mixture, and 3 ml of anhydrous ethanol was added to each gram of the mixed raw material and ground to obtain a slurry-like mixture. The mixture was ground for 30 minutes until the anhydrous ethanol was completely evaporated, and a uniform powdery mixture was obtained. (2) The uniform mixture obtained in step (1) is placed into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900℃ for 3 hours, then calcined at 1300℃ for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes and passed through a 200-mesh sieve to obtain near-infrared phosphor.

[0047] Examples 8-15 Ni in Examples 8-15 2+ Doped double perovskite-based broadband tunable near-infrared phosphors, with the chemical formulas: Sr 1.4 Ca 0.6 MgWO6:0.015Ni 2+ 、Sr 1.2 Ca 0.8 MgWO6:0.015Ni 2+ SrCaMgWO6:0.015Ni 2+ 、Sr 0.8 Ca 1.2 MgWO6:0.015Ni 2+ 、Sr 0.6 Ca 1.4 MgWO6:0.015Ni 2+ 、Sr 0.4 Ca 1.6 MgWO6:0.015Ni 2+ 、Sr 0.2 Ca 1.8 MgWO6:0.015Ni 2+ Ca2MgWO6:0.015Ni 2+。

[0048] The specific preparation steps are as follows: (1) The raw materials SrCO3, CaCO3, MgO, WO3 and NiO were weighed precisely according to the stoichiometric ratio of the chemical formulas in Examples 8-15 above to obtain a mixture. 3 ml of anhydrous ethanol was added to each gram of the mixed raw materials and ground to obtain a mud-like mixture. The mixture was ground for 30 minutes until the anhydrous ethanol was completely evaporated to obtain a uniform powder mixture. (2) The uniform mixture obtained in step (1) is loaded into a corundum crucible and placed in a muffle furnace. Under an air atmosphere, it is first pre-calcined at 900°C for 3 hours, then calcined at 1300°C for 6 hours. Finally, after naturally cooling to room temperature, it is taken out and ground for 10 minutes. After passing through a 200-mesh sieve, the corresponding near-infrared phosphor is obtained.

[0049] Figure 5 The X-ray diffraction patterns are those of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention. The diffraction peaks of the samples match the standard chart well, and no impurity peaks were observed, indicating that the synthesized series of near-infrared samples are all pure phases. Furthermore, it can be observed that with the increase of Ca... 2+ With increasing concentration, the position of the diffraction peak gradually shifts to higher angles, indicating that small-radius Ca... 2+ Ions entered the crystal lattice and replaced the large-radius Sr 2+ The ions caused the crystal lattice to shrink.

[0050] Figure 6 These are morphological images of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention. Figure 6 The prepared samples were observed to have irregular shapes, uniform particle size, and clearly distinguishable grain boundaries. Some agglomeration was observed, which is a normal phenomenon during solid-state reactions. Furthermore, with the increase of Ca... 2+ With increasing ion concentration, the sample particle size gradually increased from 2 μm to 10 μm, indicating that Ca... 2+ The introduction of [something] promotes the growth of sample particles.

[0051] Figure 7 and Figure 8 The figures show the normalized excitation and emission spectra of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention. The figures show that the normalized excitation and emission spectra exhibit the same trend, with a redshift occurring as the z-value increases. The emission peak position in the emission spectrum redshifts from 1400 nm to 1485 nm.

[0052] Figure 9 This is a graph showing the emission peak position and full width at half maximum (FWHM) variation of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention. Figure 9 It can be observed that when Ca 2+ When the doping concentration is less than 0.6, as Ca... 2+ With the increase of Ca, the peak position of the sample redshifted from 1400 nm to 1485 nm, and the FWHM broadening of the sample increased from 231 nm to 323 nm. However, due to the phase transition caused by substitution, the doping concentration decreased with increasing Ca concentration after 0.6. 2+ With the increase of , the emission peak position of the sample remained unchanged at 1485 nm, and the FWHM of the sample decreased slightly.

[0053] Figure 10 and Figure 11 The figures show the average bond length variation of the Mg-O bond and the torsion index of the [MgO6] octahedron in the tunable near-infrared phosphor structures prepared in Examples 6-15 of this invention, respectively. It can be observed that as Ca... 2+ With the increase of Ca, the average bond length of Mg / Ni-O decreases. After a sudden increase at z=0.7, it gradually decreases again due to the use of Ca. 2+ Replace Sr 2+ This forms a continuous, miscible solid solution, while Ca... 2+ The continuous incorporation of ions induces a composition-induced structural transformation. At z=0.7, the solid solution limit reaches its maximum, and the sample forms a finite solid solution. With subsequent Ca... 2+ A second phase appears in the sample with increasing concentration. The [MgO6] octahedral distortion index increases, reaching a maximum at z=0.6. This is due to the presence of Ca... 2+ Substitution increases the distortion of the [Mg / NiO6] octahedron in the sample, resulting in highly asymmetric Ni... 2+ The increase in the number of positions leads to a larger Stokes shift, explaining the emission spectrum of the tunable near-infrared phosphors prepared in Examples 6-15 as a function of Ca... 2+ The redshift and broadening gradually occur with increasing doping concentration.

[0054] Figure 12 The above are fluorescence lifetime diagrams of the tunable near-infrared phosphors prepared in Examples 6-15 of this invention. It can be observed that as Ca... 2+ With increasing substitution concentration, the fluorescence lifetime of the samples prepared in Examples 6-15 first decreased and then increased, reaching a minimum when z was 0.6. This trend is consistent with the fluorescence intensity variation trend discussed above, and is also influenced by Ca. 2+ Replace Sr 2+ This was caused by subsequent changes in the degree of distortion of the sample structure.

[0055] Application Example 1 In this application example, the Ni prepared in Example 15 is selected. 2+ Doped double perovskite-based broadband tunable near-infrared phosphors were encapsulated into NIR pc-LED devices, and their applications in night vision, vein imaging, and non-destructive testing were investigated.

[0056] The specific preparation steps are as follows: (1) Ni prepared in Example 15 was selected 2+ Doped double perovskite-based broadband tunable near-infrared phosphors were mixed with AB potting compound in a mass ratio of 1:0.5:0.5 to obtain a powder slurry. (2) The powder slurry obtained in step (1) is applied to a commercially available InGaN purple LED chip by dispensing, and then dried and cured at 100°C to obtain a NIR pc-LED device.

[0057] The resulting NIR pc-LED devices were used for night vision, vein imaging, and non-destructive testing.

[0058] Figure 13 The left side shows a schematic diagram of the NIR pc-LED device encapsulated with tunable near-infrared phosphor prepared in Example 15 in the Turn-off and Turn-on states. As can be seen from the figure, when the device is turned off, it shows a slight light blue color of the encapsulated powder (visible to the naked eye, but appears white when photographed due to the influence of external light). When the device is turned on, since the emitted infrared light is not visible to the naked eye, the encapsulated powder is excited by the LED chip and emits a light green light from the mixture of the chip and the powder.

[0059] Night vision imaging: Figure 14 This invention applies the tunable near-infrared phosphor-encapsulated NIR pc-LED device prepared in Example 15 to night vision. Under fluorescent light, the shape of the potted succulent is clearly visible. When the fluorescent light is off, the succulent in the picture is completely black, with no outline details. However, under NIR pc-LED illumination, the outline of the potted succulent can be clearly observed.

[0060] Vein imaging: Figure 15 This invention demonstrates the application of the tunable near-infrared phosphor-encapsulated NIR pc-LED device prepared in Example 15 in vein imaging. The left and right halves of the image show images of the back of a human hand under fluorescent light and NIR pc-LED illumination, respectively. The images clearly show the distribution of blood vessels in the back of the hand under NIR pc-LED illumination, revealing the thickness and specific course of the veins. This demonstrates the excellent application potential of NIR pc-LED in clear and rapid human vein imaging.

[0061] Non-destructive testing: Figure 16This invention illustrates the application of the tunable near-infrared phosphor-encapsulated NIR pc-LED device prepared in Example 15 in the non-destructive testing of carbon sketch marks on the underlying surface of an oil painting. The left half of the image shows the entire oil painting captured by a visible light camera; the middle half shows magnified views of three sections; and the right half shows three partial patterns captured by a near-infrared camera. By comparing the imaging effects of these three partial patterns under visible light and near-infrared cameras, it is found that the carbon sketch marks on the underlying surface of the oil painting are clearly visible under NIR pc-LED light. This is due to the strong penetration of NIR-II region light and the strong absorption of near-infrared light by carbon. This will help viewers gain a deeper understanding of the specific details of the creation process of oil paintings and provide further standards for identifying valuable artworks.

[0062] Application Example 2 In this application example, the Ni prepared in Example 10 is selected. 2+ A doped double perovskite-based broadband tunable near-infrared phosphor was encapsulated into a NIR pc-LED device, and its application in detecting carbon traces in the underlayer of watercolor paintings was investigated.

[0063] The specific preparation steps are as follows: (1) Ni prepared in Example 10 was selected 2+ Doped double perovskite-based broadband tunable near-infrared phosphors were mixed with AB potting compound in a mass ratio of 1:0.5:0.5 to obtain a powder slurry. (2) The powder slurry obtained in step (1) is applied to a commercially available InGaN purple LED chip by dispensing, and then dried and cured at 100°C to obtain a NIR pc-LED device.

[0064] The obtained NIR pc-LED device was tested with carbon.

[0065] Figure 13 The right side shows a schematic diagram of the NIR pc-LED device encapsulated with tunable near-infrared phosphor prepared in Example 10 in the Turn-off and Turn-on states in Application Example 2. As can be seen from the figure, when the device is turned off, it shows a slight light blue color of the encapsulated powder (visible to the naked eye, but appears white when photographed due to the influence of external light). When the device is turned on, since the emitted infrared light is not visible to the naked eye, the encapsulated powder is excited by the LED chip and emits a light green light from the mixture of the chip and the powder.

[0066] Carbon trace detection: Figure 17This invention's application example 2 uses the tunable near-infrared phosphor-encapsulated NIR pc-LED device prepared in Example 10 for detecting carbon traces in watercolor paintings. The left half of the image shows the finished watercolor painting captured by a visible light camera, while the right half shows the pattern captured by a near-infrared camera. The comparison reveals that under NIR pc-LED illumination, the outline of the carbon sketch covering the bottom of the watercolor painting is clearly visible, while the watercolor paint itself is transparent and invisible. This is due to the different absorption capabilities of watercolor and carbon for near-infrared light. This will help viewers gain a deeper understanding of the specific details of the creative process of such artworks.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Ni 2+ The doped double perovskite-based broadband tunable near-infrared phosphor is characterized by, Its chemical formula is as follows: (Sr 1-z Ca z )2MgWO6:xNi 2+ , where 0.005≤x≤0.025, 0≤z≤1.

0.

2. The Ni according to claim 1 2+ The doped double perovskite-based broadband tunable near-infrared phosphor is characterized by, In the chemical formula, when x = 0.005, 0.01, 0.015, 0.02, or 0.025, and z = 0, the emission wavelength range of the infrared phosphor is 1000-1700 nm, and the full width at half maximum (FWHM) is 200-250 nm. Ni 2+ It is the luminescent center.

3. The Ni according to claim 1 2+ The doped double perovskite-based broadband tunable near-infrared phosphor is characterized by, When x = 0.015 and z = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 in the chemical formula, the emission wavelength range of the infrared phosphor is 1000-1750 nm, and the full width at half maximum (FWHM) is 200-350 nm. Ni 2+ It is the luminescent center.

4. The Ni as described in any one of claims 1 to 3 2+ A method for preparing doped double perovskite-based broadband tunable near-infrared phosphors, characterized in that, Includes the following steps: 1) Accurately weigh the required raw materials according to the stoichiometric ratio of the chemical formula; 2) Transfer the weighed raw materials to a mortar and grind with anhydrous ethanol to obtain a slurry-like mixture. Grind for 25-35 minutes until the anhydrous ethanol is completely evaporated to obtain a powdery, uniform mixture. 3) Place the uniform mixture obtained in step 2) into a muffle furnace, pre-calcine it in an air atmosphere, then calcine it at a high temperature, and finally obtain the calcined product. 4) After naturally cooling to room temperature, the calcined product is removed from the muffle furnace, ground, and sieved to finally obtain the Ni. 2+ Doped double perovskite-based broadband tunable near-infrared phosphor.

5. The Ni according to claim 4 2+ A method for preparing doped double perovskite-based broadband tunable near-infrared phosphors, characterized in that, In step 1), the raw materials are SrCO3, CaCO3, MgO, WO3 and NiO.

6. The Ni according to claim 4 2+ A method for preparing doped double perovskite-based broadband tunable near-infrared phosphors, characterized in that, In step 3), the pre-firing temperature is 850-950℃ and the firing time is 2-4h; the high-temperature firing temperature is 1250-1350℃ and the firing time is 5-7h.

7. The Ni according to claim 4 2+ A method for preparing doped double perovskite-based broadband tunable near-infrared phosphors, characterized in that, In step 4), the grinding time is 5-15 minutes, and the sieving is done through a 100-300 mesh sieve.

8. A NIR pc-LED, characterized in that, Including the Ni according to any one of claims 1 to 3 2+ Doped double perovskite-based broadband tunable near-infrared phosphor.

9. The application of the NIR pc-LED as described in claim 8 in night vision, medical imaging and non-destructive testing.

10. The method for preparing NIR pc-LED as described in claim 8, characterized in that, Includes the following steps: applying the Ni as described in any one of claims 1 to 3 2+ Doped double perovskite-based broadband tunable near-infrared phosphors were mixed with AB potting compound at a mass ratio of 1:0.5:0.5 to obtain a powder slurry. The obtained powder slurry is applied to the purple LED chip by dispensing, and then dried and cured at 90-120℃ to obtain NIR pc-LED.

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