Nickel-containing near-infrared fluorescent powder and preparation method thereof
By forming lattice defects in a barium gallate matrix and doping with Ni2+ ions, combined with 635 nm photoexcitation, a broadband near-infrared phosphor covering 1050-1800 nm was prepared. This solved the problem of lossless extension of Ni2+ doped phosphor in the 1000-1300 nm range, improved imaging depth and resolution, and is suitable for high-resolution deep biological tissue imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEAST NORMAL UNIVERSITY
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-01
AI Technical Summary
Existing Ni2+ doped near-infrared phosphors have difficulty achieving lossless extension of emission wavelength in the 1000-1300 nm range, resulting in limited imaging depth and resolution. Furthermore, co-doped ions are prone to causing luminescence quenching or require multi-wavelength excitation.
By forming lattice defects in a barium gallate matrix and doping with Ni2+ ions, combined with 635 nm single-wavelength light excitation, a broadband near-infrared phosphor covering the 1050-1800 nm range was prepared by utilizing the combination of matrix defects and Ni2+ ion emission spectral bands.
This technology enables the emission wavelength of near-infrared phosphors to cover the entire NIR-II region under single-wavelength excitation, improving imaging depth and resolution, and making it suitable for high-resolution deep biological tissue imaging diagnostic equipment.
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Figure CN121950299A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the preparation process of near-infrared phosphors, and particularly to a nickel ion-doped barium gallate-based near-infrared phosphor and its preparation method. Background Technology
[0002] Near-infrared luminescent materials with emission wavelengths in the 700-1800 nm range have attracted much attention due to their high penetration into biological tissues, lack of tissue-free self-fluorescence, high matching with the characteristic absorption of organic molecules, and low scattering in media such as air and biological tissues. They hold broad application prospects in numerous fields, including bioimaging, functionalized nanomedicine design, food detection, spectral analysis, and night vision surveillance. Among these, phosphors doped with transition metal ions such as chromium, iron, cobalt, and nickel, which possess 3d electronic configurations, often exhibit broad-band near-infrared emission characteristics after excitation due to the hypersensitivity of the excited-state energy levels of these transition metal ions to the surrounding local crystal field strength and symmetry. Therefore, these near-infrared phosphors have significant application potential in the manufacture of broadband near-infrared emission special light source equipment for spectral analysis and biomedicine. Furthermore, by combining them with phosphor-converted LED technology, long-life, economical, and miniaturized special near-infrared light sources can be manufactured, enabling the development of portable optical diagnostic and analytical devices suitable for home medical and biosafety applications. In particular, divalent nickel ions (Ni...) 2+ The emission wavelength of Ni-doped near-infrared phosphors is mainly concentrated in the 1300-1700 nm range, which is within the near-infrared II optical transmission biological window (NIR-II: 1000-1800 nm). Compared with other transition ion-doped phosphors whose emission wavelength is within the near-infrared I optical transmission biological window (NIR-I: 700-900 nm), its NIR-II emission light can penetrate more than 10 times deeper than NIR-I light, and it produces almost no tissue autofluorescence, making it more suitable for the design of compact near-infrared light sources for radiation-free, high-resolution deep biological tissue imaging diagnostic equipment. However, its emission wavelength does not cover the 1000-1300 nm wavelength range in the near-infrared II region. Related studies have shown that water absorption of light in the 1000-1300 nm wavelength range is significantly reduced compared to light in the 1300-1700 nm range. As is well known, water accounts for a significant proportion in various biological tissues, making up more than 2 / 3 of the cytosol. Therefore, for Ni... 2+ To overcome the limitations of current imaging depth and resolution and expand its biomedical application scenarios, the bioimaging application of near-infrared phosphors urgently needs to extend its emission wavelength to the 1000-1300 nm range.
[0003] Currently, Ni 2+Methods for extending the near-infrared spectrum of doped phosphors to the 1000-1300 nm range mainly include two technical strategies. One strategy is to enhance the performance of Ni by co-doping with impurity ions or screening matrix materials with strong crystal field environments. 2+ This can be achieved by increasing the local crystal field strength of Ni. Studies have shown that the excited state energy level of nickel ions typically increases with the enhancement of the local crystal field environment, resulting in a blue shift in the corresponding emission wavelength, which can tune the emission peak to the 1000-1300 nm range. However, this strategy leads to an overall shift of the emission peak towards shorter wavelengths, meaning that the emission portion located at 1300-1700 nm will weaken or disappear. Another strategy is to increase the local crystal field strength of Ni... 2+ This is achieved by co-doping phosphors with metal ions such as chromium and neodymium that emit light in the 1000-1300 nm range. Compared to the previous strategy, this strategy generally does not cause Ni... 2+ The emission peak of the ions shifts. However, due to the effect of co-doped ions on the original Ni... 2+ Dopant site crowding, co-doped ions and Ni 2+ The overlapping of ion excited-state energy levels can lead to a relatively high local dopant ion concentration, inducing luminescence quenching and weakening the overall luminescence intensity. Reducing the concentration of co-doped luminescent center ions and Ni... 2+ Even with a lower doping concentration, the reduced number of luminescent centers still leads to a decrease in luminescence intensity. Related studies have shown that weaker luminescence intensity results in a lower signal-to-noise ratio in the image, severely impacting image quality and depth. Furthermore, using different luminescent centers typically requires different wavelengths of excitation light, increasing the difficulty of its application. Therefore, by employing the above-mentioned strategy, under single-wavelength excitation, current Ni... 2+ Doped phosphors failed to achieve lossless wavelength extension of emission in the 1000-1300 nm near-infrared range. Summary of the Invention
[0004] To solve the above-mentioned technical problems, the present invention utilizes matrix defect luminescence and Ni 2+ By combining ion emission spectral bands, a broadband emitting near-infrared phosphor for a special near-infrared light source with an emission wavelength covering the range of 1050-1800 nm was prepared.
[0005] The present invention provides a nickel-containing near-infrared phosphor, which is prepared by the following method:
[0006] Step 1: Take a certain amount of barium carbonate, gallium oxide, nickel oxide and isopropanol to prepare a suspension. The volume molar concentrations of barium, gallium and nickel ions in the suspension are 1 M, 1.994-1.99 M and 0.006-0.01 M, respectively.
[0007] Step 2: Take a certain amount of the above suspension and grind it for a certain time to obtain a fine paste-like reactant; then, bake the paste-like reactant at 50-80℃ until the paste-like reactant is completely dry.
[0008] Step 3: Grind the dried reactants again for a certain period of time to finally obtain the powder reactants;
[0009] Step 4: Place the powder reactant in a mold and press it to obtain a dense, sheet-like reactant;
[0010] Step 5: Heat-treat the sheet-like reactants under a low vacuum atmosphere. First, heat from room temperature at a certain heating rate, and hold at 400°C for 30-50 minutes. Then, continue heating at the same heating rate to 800°C and hold at 800°C for 30-50 minutes. Finally, continue heating at the same heating rate to 1000°C and hold at 1000°C for 2-4 hours.
[0011] Step 6: Cool the product to 600℃ at a certain cooling rate for the first time and hold it at that temperature for 30-60 minutes; then cool it to room temperature at a certain cooling rate for the second time and remove the heat-treated sheet-like reactant.
[0012] Step 7: After heat treatment, the sheet-like reactants are crushed and ground to obtain nickel ion-doped barium gallate-based near-infrared phosphor (BaGa2O4:Ni) with a particle size in the range of 1-5 micrometers.
[0013] Preferably, the total volumetric molar concentration of gallium and nickel ions in step 1 is 2M.
[0014] As a preferred method, the grinding method in step 2 is to place the agate in an agate grinder and grind it at a constant speed of 50-70 rpm for 20-30 minutes.
[0015] Preferably, the grinding method in step 3 is to place the agate in an agate grinder and grind it at a constant speed of 20-40 rpm for 10-20 minutes.
[0016] Preferably, the compression method in step 4 is to compress at 15-25 MPa for 1-3 minutes.
[0017] Preferably, the vacuum level of the low vacuum atmosphere in step 5 is 5-0.5 Pa; the heating rate is 10℃ / min.
[0018] Preferably, the cooling rate for the first cooling step in step 6 is 5°C / minute; and the cooling rate for the second cooling step is 15°C / minute.
[0019] As a preferred method, the grinding method in step 7 is to place the agate in an agate grinder and grind it at a constant speed of 50-70 rpm for 3-5 hours.
[0020] The prepared nickel-containing near-infrared phosphor, under 635 nm photoexcitation, exhibits light emission in the 1050-1400 nm range originating from matrix defects and Ni. 2+ The ultra-broadband near-infrared emission consists of light emission from ions in the 1300-1800 nm range.
[0021] The nickel-containing near-infrared phosphor prepared by this invention can be used as a compact special near-infrared phosphor to convert light-emitting diode light source for high-resolution deep biological tissue imaging diagnostic equipment.
[0022] Working principle of the invention:
[0023] (1) Based on the weak reducing properties of low vacuum and high temperature environment, specific lattice defects are formed in the barium gallate matrix, thereby generating near-infrared emission (1050-1400 nm) originating from matrix defects.
[0024] (2)Ni 2+ With an ionic radius similar to that of gallium ions, it replaces gallium ions in the barium gallate matrix and occupies tetrahedral sites. The surrounding crystal field environment is relatively weak, resulting in broadband emission of 1300-1800 nm.
[0025] (3) Under single-wavelength light excitation at 635 nm, barium gallate matrix and Ni 2+ Simultaneously excited, the matrix defects emit light in the 1050-1400 nm range, and Ni... 2+ The 1300-1800 nm light emission bands of the ions superimpose to produce an ultra-broad spectral band of near-infrared emission covering 1050-1800 nm.
[0026] The beneficial effects of this invention are:
[0027] The nickel-doped barium gallate-based near-infrared phosphor prepared in this invention has the same crystal structure as standard hexagonal barium gallate. Under 635 nm light excitation, it exhibits ultra-wideband near-infrared emission, almost covering the entire NIR-II optical transmission biological window (1050-1800 nm). Compared with other nickel-doped phosphors (1300-1800 nm), it has a wider near-infrared emission band. Therefore, the nickel-doped barium gallate-based near-infrared phosphor prepared in this invention, based on its near-complete NIR-II emission, is more suitable for the design of compact special near-infrared phosphor-converted light-emitting diode light sources for high-resolution deep biological tissue imaging diagnostic equipment. Similarly, due to its ultra-wideband NIR-II emission without ionizing radiation, it can be used in various biological tissue scenarios such as fat, muscle, and endothelium, thereby promoting the development of multi-purpose imaging diagnostic analysis technologies and equipment suitable for daily home medical care and safe and friendly to special groups such as children, pregnant women, and the elderly. Attached Figure Description
[0028] Figure 1 The X-ray diffraction pattern of the nickel ion-doped barium gallate-based near-infrared phosphor prepared in this invention;
[0029] Figure 2 The emission spectrum of the nickel ion-doped barium gallate-based near-infrared phosphor prepared in this invention under 635 nm light excitation;
[0030] Figure 3 This is a scanning electron microscope image of the nickel ion-doped barium gallate-based near-infrared phosphor prepared in this invention.
[0031] Figure 4 The X-ray diffraction pattern of the undoped barium gallate-based near-infrared emitting phosphor prepared in this invention;
[0032] Figure 5 The emission spectra of the undoped barium gallate matrix and the nickel-doped barium gallate-based near-infrared phosphor prepared in this invention under 635 nm light excitation. Detailed Implementation
[0033] Example 1
[0034] This embodiment provides a nickel-containing near-infrared phosphor, which is prepared by the following method:
[0035] Step 1: Take a certain amount of barium carbonate, gallium oxide, nickel oxide and isopropanol to prepare a suspension. The volume molar concentrations of barium, gallium and nickel ions in the suspension are 1 M, 1.99 M and 0.01 M, respectively.
[0036] Step 2: Place 2 ml of the above suspension in an agate grinder and grind it at a constant speed of 60 rpm for 30 minutes to obtain a fine paste-like reaction product; then, place the paste-like reaction product in an electric resistance furnace and bake it at 70°C until the paste-like reaction product is completely dry.
[0037] Step 3: Place the dried reactants back into the agate grinder and grind them at a constant speed of 30 rpm for 10 minutes to finally obtain the powder reactants.
[0038] Step 4: Place the powder reactant into a circular mold with an inner diameter of 13 mm and press it at 20 MPa for 1 minute to obtain a dense, round, flake-shaped reactant.
[0039] Step 5: Place the disc-shaped reactants in a tube furnace and heat-treat them under a low vacuum atmosphere (1 Pa). First, heat from room temperature at a heating rate of 10 °C / min, and hold at 400 °C for 40 minutes. Then, continue heating at the same heating rate to 800 °C and hold at 800 °C for 50 minutes. Finally, continue heating at the same heating rate to 1000 °C and hold at 1000 °C for 4 hours.
[0040] Step 6: After the heat treatment is completed, the temperature is lowered to 600℃ for the first time at a cooling rate of 5℃ / min and held at that temperature for 40 minutes; then, the temperature is lowered to room temperature for the second time at a cooling rate of 15℃ / min, and the heat-treated disc-shaped reactants are taken out.
[0041] Step 7: After heat treatment, the disc-shaped reactants are crushed and placed in an agate grinder. They are then ground at a constant speed of 60 rpm for 5 hours to obtain nickel ion-doped barium gallate-based near-infrared phosphor (BaGa2O4:Ni) with particle size in the range of 1-5 micrometers.
[0042] See Figure 1-3 As shown, under 635 nm light excitation, this nickel ion-doped barium gallate exhibits ultra-broad spectral near-infrared II emission covering the 1050-1800 nm range.
[0043] Example 2
[0044] This embodiment provides a nickel-containing near-infrared phosphor, which is prepared by the following method:
[0045] Step 1: Take a certain amount of barium carbonate, gallium oxide, nickel oxide and isopropanol to prepare a suspension. The volume molar concentrations of barium, gallium and nickel ions in the suspension are 1 M, 1.994 M and 0.006 M, respectively.
[0046] Step 2: Place 2 ml of the above suspension in an agate grinder and grind it at a constant speed of 70 rpm for 30 minutes to obtain a fine paste-like reaction product; then, place the paste-like reaction product in an electric resistance furnace and bake it at 60°C until the paste-like reaction product is completely dry.
[0047] Step 3: Place the dried reactants back into the agate grinder and grind them at a constant speed of 40 rpm for 20 minutes to finally obtain the powder reactants.
[0048] Step 4: Place the powder reactant into a circular mold with an inner diameter of 13 mm and press it at 15 MPa for 1.5 minutes to obtain a dense, round, flake-shaped reactant.
[0049] Step 5: Place the disc-shaped reactants in a tube furnace and heat-treat them under a low vacuum atmosphere (0.8 Pa). First, heat from room temperature at a heating rate of 10°C / min, and hold at 400°C for 30 minutes. Then, continue heating at the same heating rate to 800°C and hold at 800°C for 40 minutes. Finally, continue heating at the same heating rate to 1000°C and hold at 1000°C for 2 hours.
[0050] Step 6: After the heat treatment is completed, the temperature is lowered to 600℃ for the first time at a cooling rate of 5℃ / min and held at that temperature for 30 minutes; then, the temperature is lowered to room temperature for the second time at a cooling rate of 15℃ / min, and the heat-treated disc-shaped reactants are taken out.
[0051] Step 7: After heat treatment, the disc-shaped reactants are crushed and placed in an agate grinder. They are then ground at a constant speed of 50 rpm for 3 hours to obtain nickel ion-doped barium gallate-based near-infrared phosphors (BaGa2O4:Ni) with particle sizes in the range of 1-5 micrometers.
[0052] Comparative example:
[0053] The near-infrared phosphor provided in this comparative example is prepared by the following method:
[0054] Step 1: Take a certain amount of barium carbonate, gallium oxide and isopropanol to prepare a suspension. The volume molar concentrations of barium and gallium ions in the suspension are 1 M and 2 M, respectively.
[0055] Step 2: Place 2 ml of the above suspension in an agate grinder and grind it at a constant speed of 70 rpm for 30 minutes to obtain a fine paste-like reaction product; then, place the paste-like reaction product in an electric resistance furnace and bake it at 60°C until the paste-like reaction product is completely dry.
[0056] Step 3: Place the dried reactants back into the agate grinder and grind them at a constant speed of 40 rpm for 20 minutes to finally obtain the powder reactants.
[0057] Step 4: Place the powder reactant into a circular mold with an inner diameter of 13 mm and press it at 15 MPa for 1.5 minutes to obtain a dense, round, flake-shaped reactant.
[0058] Step 5: Place the disc-shaped reactants in a tube furnace and heat-treat them under a low vacuum atmosphere (0.8 Pa). First, heat from room temperature at a heating rate of 10°C / min, and hold at 400°C for 30 minutes. Then, continue heating at the same heating rate to 800°C and hold at 800°C for 40 minutes. Finally, continue heating at the same heating rate to 1000°C and hold at 1000°C for 2 hours.
[0059] Step 6: After the heat treatment is completed, the temperature is lowered to 600℃ for the first time at a cooling rate of 5℃ / min and held at that temperature for 30 minutes; then, the temperature is lowered to room temperature for the second time at a cooling rate of 15℃ / min, and the heat-treated disc-shaped reactants are taken out.
[0060] Step 7: After heat treatment, the disc-shaped reactants are crushed and placed in an agate grinder. They are then ground at a constant speed of 50 rpm for 3 hours to obtain barium gallate-based near-infrared emitting phosphor (BaGa2O4) without nickel ion doping.
[0061] See appendix Figure 4 and Figure 5 As shown, both nickel-doped and undoped infrared phosphors possess a hexagonal barium gallate crystal structure. Under 635 nm photoexcitation, the nickel-doped sample exhibits an ultra-broad spectral near-infrared emission of 1050-1800 nm, which is attributed to matrix defect emission (1050-1400 nm) and Ni... 2+ Composed of ion emission (1300-1800 nm).
Claims
1. A method for preparing a nickel-containing near-infrared phosphor, characterized in that: Includes the following steps: Step 1: Take a certain amount of barium carbonate, gallium oxide, nickel oxide and isopropanol to prepare a suspension. The volume molar concentrations of barium, gallium and nickel ions in the suspension are 1 M, 1.994-1.99 M and 0.006-0.01 M, respectively. Step 2: Take a certain amount of the above suspension and grind it for a certain time to obtain a fine paste-like reactant; then, bake the paste-like reactant at 50-80℃ until the paste-like reactant is completely dry. Step 3: Grind the dried reactants again for a certain period of time to finally obtain the powder reactants; Step 4: Place the powder reactant in a mold and press it to obtain a dense, sheet-like reactant; Step 5: Heat-treat the sheet-like reactants under a low vacuum atmosphere. First, heat from room temperature at a certain heating rate, and hold at 400°C for 30-50 minutes. Then, continue heating at the same heating rate to 800°C and hold at 800°C for 30-50 minutes. Finally, continue heating at the same heating rate to 1000°C and hold at 1000°C for 2-4 hours. Step 6: Cool the product to 600℃ at a certain cooling rate for the first time and hold it at that temperature for 30-60 minutes; then cool it to room temperature at a certain cooling rate for the second time and remove the heat-treated sheet-like reactant. Step 7: After heat treatment, the sheet-like reactants are crushed and ground to obtain nickel ion-doped barium gallate-based near-infrared phosphor (BaGa2O4:Ni) with a particle size in the range of 1-5 micrometers.
2. The method for preparing a nickel-containing near-infrared phosphor according to claim 1, characterized in that: The total volumetric molar concentration of gallium and nickel ions in step 1 is 2M.
3. The method for preparing a nickel-containing near-infrared phosphor according to claim 1, characterized in that: The compression method in step 4 is to compress at 15-25 MPa for 1-3 minutes.
4. The method for preparing a nickel-containing near-infrared phosphor according to claim 1, characterized in that: The vacuum level of the low vacuum atmosphere in step 5 is 5-0.5 Pa; the heating rate is 10℃ / min.
5. The method for preparing a nickel-containing near-infrared phosphor according to claim 1, characterized in that: The cooling rate for the first cooling step in step 6 is 5°C / minute; the cooling rate for the second cooling step is 15°C / minute.
6. The method for preparing a nickel-containing near-infrared phosphor according to claim 1, characterized in that: The grinding method in step 7 is to place the agate in an agate grinder and grind it at a constant speed of 50-70 rpm for 3-5 hours.
7. A nickel-containing near-infrared phosphor, characterized in that: The nickel-containing near-infrared phosphor prepared according to any one of claims 1-6 exhibits an ultra-broad band near-infrared emission under 635 nm light excitation, consisting of 1050-1400 nm light emission from the matrix and 1300-1800 nm light emission from nickel ions.