A rare earth doped broadband short-wave infrared fluorescent material, a preparation method and application thereof

Abstract

The present application relates to a kind of rare earth doped broadband short wave infrared fluorescent material and its preparation method and application, belong to light source material technical field.The molecular formula of the rare earth doped broadband short wave infrared fluorescent material of the present application is M 2‑2m(x+y) O3·NAl 1‑n(x+y) O2:xYb 3+ / yTm 3+ , wherein, 0.05≤x≤0.85, 0<y≤0.15, m+n=1;M is selected from Y 3+ Or Gd 3+ , N is selected from Li + , Na + Or K + The rare earth doped broadband short wave infrared fluorescent material is two-phase solid solution with M2O3 crystal phase as main, with NAlO2 crystal phase as auxiliary;It can be excited by 950nm-1100nm range light, and the emission wavelength range is about 1500nm-2100nm, and the emission band half-width is about 350nm-450nm.

Description

Technical Field

[0001] The present invention belongs to the technical field of light source materials, and particularly relates to a rare earth-doped broadband short-wave infrared fluorescent material, a preparation method thereof, and an application thereof. Background Art

[0002] Short-wave infrared light has important applications in many fields. In the military field, short-wave infrared light can be used in military and security equipment such as infrared night vision devices, infrared thermal imagers, and infrared lasers. It can help personnel observe and detect in the dark or low-light conditions and is used for target recognition and tracking. In addition, short-wave infrared light also has extensive applications in the medical field, such as infrared scanning and optical imaging technology, which can be used to detect and diagnose abnormalities in human tissues, such as tumors, vascular diseases, and skin diseases. In industrial manufacturing, short-wave infrared light can be used for material characterization, quality control, and non-contact measurement, and can provide information about the chemical composition, thermal distribution, and surface characteristics of materials, helping to improve the production process and product quality. Finally, short-wave infrared light can be used to detect atmospheric pollutants and temperature changes on the Earth's surface, which can help monitor air quality, climate change, and environmental pollution. Short-wave infrared light has broad application prospects in the fields of military, security monitoring, medical diagnosis, etc.

[0003] Some challenges are faced in the application and development process of short-wave infrared luminescent materials. First, the synthesis and preparation process of short-wave infrared luminescent materials may be complex, and it is necessary to control the composition, structure, purity, etc. of the materials to ensure that the materials have the required luminescent properties. Second, the emission bandwidth of existing short-wave infrared fluorescent materials is small, and the emission spectrum of the fluorescent material cannot effectively cover the vibration absorption band of organic molecular groups, resulting in low accuracy of molecular detection and recognition. Finally, the problem of degradation or damage may occur in short-wave infrared luminescent materials under long-term and high-power excitation. How to improve the stability and reliability of the materials to meet the requirements of practical applications is also a challenge. Overcoming these challenges requires comprehensive research and technological innovation, which ultimately promotes the development and application of short-wave infrared luminescent materials. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a rare earth-doped broadband short-wave infrared fluorescent material, a preparation method thereof, and an application thereof.

[0005] The first object of the present invention is to provide a rare earth-doped broadband short-wave infrared fluorescent material with the molecular formula of M 2-2m(x+y) O3·NAl 1-n(x+y) O2:xYb 3+ / yTm 3+ , where 0.05 ≤ x ≤ 0.85, 0 < y ≤ 0.15, and m + n = 1; M is selected from Y 3+ or Gd 3+N is selected from Li + Na + or K + Yb 3+ and Tm 3+ Ions randomly occupy M 3+ And Al 3+ Grid position.

[0006] In one embodiment of the present invention, the rare earth-doped broadband short-wave infrared fluorescent material is a two-phase solid solution with M2O3 crystal phase as the main phase and NAlO2 crystal phase as the auxiliary phase.

[0007] In one embodiment of the present invention, the excitation wavelength of the rare earth-doped broadband short-wave infrared fluorescent material is 950nm-1100nm.

[0008] In one embodiment of the present invention, the emission wavelength of the rare earth-doped broadband short-wave infrared fluorescent material is 1500nm-2100nm.

[0009] In one embodiment of the present invention, the emission band half-width of the rare earth-doped broadband short-wave infrared fluorescent material is 350nm-450nm.

[0010] The second objective of this invention is to provide a method for preparing the rare-earth-doped broadband short-wave infrared fluorescent material, wherein the preparation method is a high-temperature solid-state reaction method.

[0011] In one embodiment of the present invention, the following steps are included: according to the molecular formula M 2-2m(x+y) O3·NAl 1-n(x+y) O2:xYb 3+ / yTm 3+ The raw materials M2O3, N2CO3, Al2O3, Yb2O3 and Tm2O3 were weighed according to the stoichiometric ratio of M, N, Al, Yb and Tm. After being mixed evenly, they were calcined, ground, sieved, washed with water and dried to obtain the rare earth-doped broadband short-wave infrared fluorescent material.

[0012] In one embodiment of the present invention, the calcination is carried out by heating to 1100℃-1200℃ at a rate of 5℃ / min-10℃ / min and calcining for 8h-10h.

[0013] In one embodiment of the present invention, the sieving is through a 300-mesh sieve.

[0014] In one embodiment of the present invention, the water washing is performed by washing with deionized water 1-3 times.

[0015] In one embodiment of the present invention, the drying temperature is 60°C-120°C.

[0016] The third objective of this invention is to provide a short-wave infrared PC-LED device by encapsulating the rare-earth-doped broadband short-wave infrared fluorescent material in an infrared light-emitting diode to obtain the short-wave infrared PC-LED device.

[0017] In one embodiment of the present invention, the wavelength of the infrared light-emitting diode is 975nm.

[0018] The technical solution of the present invention has the following advantages compared with the prior art:

[0019] (1) The rare earth-doped broadband short-wave infrared fluorescent material of the present invention uses Yb 3+ As a sensitizer, Tm 3+ As an activator, Yb 3+ After ions absorb energy from the excitation source, they transfer their excited-state energy to Tm. 3+ Ions, then Tm 3+ ion 3 F4 excited-state radiative transition to 3 H6 emits short-wave infrared photons from its ground state; this luminescence process is a downconversion energy transfer. Due to the different crystal field strengths of M2O3 and NAlO2, Tm... 3+ Ionic 3 F4 and 3 The H6 energy level exhibits different degrees of splitting in these two crystal fields. 3 The F4 energy level emission band exhibits a slight blue shift and red shift, and the two emission bands superimpose to form broadband shortwave infrared emission.

[0020] (2) The rare earth-doped broadband short-wave infrared fluorescent material described in this invention can be excited by light in the range of 950nm-1100nm, with an emission wavelength range of about 1500nm-2100nm and an emission band half-width of about 350nm-450nm.

[0021] (3) The rare earth-doped broadband short-wave infrared fluorescent material of the present invention is synthesized by high-temperature solid-state reaction method. The preparation process is simple and easy to mass-produce. The material has stable chemical properties and good luminescence performance. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0023] Figure 1 Y, as described in Embodiment 1 of the present invention 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ Electron scanning microscope images;

[0024] Figure 2 Y, as described in Embodiment 1 of the present invention 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ X-ray diffraction pattern;

[0025] Figure 3 Y, as described in Embodiment 1 of the present invention 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ Emission spectrum under 975nm excitation;

[0026] Figure 4 Y, as described in Embodiment 1 of the present invention 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ The luminescence thermal stability test diagrams are shown; where Figure a is the emission intensity at different temperatures, and Figure b is the integrated intensity of the emission band in Figure a.

[0027] Figure 5 YO3·NaAl from Embodiment 2 of the present invention 0.5 O2:0.85Yb 3+ / 0.15Tm 3+ Emission spectrum under 975nm excitation;

[0028] Figure 6 Gd in Embodiment 3 of the present invention 1.948 O3·KAl 0.974 O2:0.05Yb 3+ / 0.002Tm 3+ Emission spectrum under 975nm excitation;

[0029] Figure 7 This is a transmission electron microscope image of β-NaYF4:Yb / Tm nanocrystals from Comparative Example 1 of this invention.

[0030] Figure 8 The emission spectrum of β-NaYF4:Yb / Tm nanocrystals in Comparative Example 1 of this invention under 975 nm excitation;

[0031] Figure 9 Y is the comparative example 2 of the present invention. 1.79 O3·LiAl 0.895 O2:0.21Yb 3+ Emission spectrum of the material under 975nm excitation;

[0032] Figure 10 Y, which is the comparative example 3 of the present invention1.79 Emission spectrum of O3:0.2Yb / 0.01Tm material under 975nm excitation. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0034] Example 1

[0035] The rare earth-doped Y of the present invention 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ (x=0.2, y=0.01, m=n=0.5) Broadband shortwave infrared fluorescent materials and their preparation methods, specifically including the following steps:

[0036] S1. Weigh out the following raw materials: Y2O3 0.895 mmol, Li2CO3 0.50 mmol, Al2O3 0.448 mmol, Yb2O3 0.10 mmol, Tm2O3 0.005 mmol;

[0037] S2. After thoroughly mixing the weighed raw materials, calcine them in air at a rate of 8℃ / min to 1150℃ for 9 hours, and then allow them to cool naturally to room temperature to obtain the calcined product.

[0038] S3. After thoroughly grinding the calcined product and passing it through a 300-mesh sieve, wash it three times with deionized water. The centrifuged precipitate is then dried at 100°C to obtain the product with the molecular formula Y. 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ Rare earth-doped broadband short-wave infrared fluorescent materials.

[0039] Y 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ electronic scan images such as Figure 1 As shown, from Figure 1 It can be seen that the fluorescent material consists of solid particles with varying sizes from ~0.5μm to 5μm. Although the particle size is large, the material is prepared by a high-temperature solid-state method, resulting in high yield and a simple process.

[0040] X-ray diffraction pattern as follows Figure 2 As shown, from Figure 2 It can be seen that Y 1.79 O3·LiAl0.895 O2:0.2Yb 3+ / 0.01Tm 3+ The crystal phase is a two-phase solid solution of Y2O3·LiAlO2.

[0041] Y 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ The emission spectrum under 975nm excitation is as follows Figure 3 As shown, from Figure 3 It can be seen that the emission wavelength range is ~1500nm-2100nm, and the half-width at half maximum (WHM) of the emission band reaches ~400nm.

[0042] Y 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ The results of the luminescence thermal stability test are as follows Figure 4 As shown, Figure 4 a represents the short-wave infrared emission spectral intensity of the sample of the present invention at different temperatures. Figure 4 b is Figure 4 The integrated intensity of the emission band a, normalized to the integrated intensity at 30°C, shows that compared to the short-wave infrared emission intensity at 30°C, the emission intensity at 130°C decreases by only 3%, at 180°C by only 10%, and at 230°C by only 17%. Typically, the operating temperature of a PC-LED lamp is below 100°C. In this embodiment, Y... 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ It can still work normally at a high temperature of 130℃, which indicates that Y 1.79 O3·LiAl 0.895 O2:0.2Yb 3+ / 0.01Tm 3+ It exhibits good luminescence and thermal stability.

[0043] Example 2

[0044] The rare earth-doped YO3·NaAl of the present invention 0.5 O2:0.85Yb 3+ / 0.15Tm 3+ (x=0.85, y=0.15, m=n=0.5) Broadband shortwave infrared fluorescent material and its preparation method, specifically including the following steps:

[0045] S1. Weigh out the following raw materials: Y2O3 0.5 mmol, Na2CO3 0.50 mmol, Al2O3 0.25 mmol, Yb2O3 0.425 mmol, Tm2O3 0.075 mmol;

[0046] S2. After thoroughly mixing the weighed raw materials, calcine them in air at a rate of 8℃ / min to 1150℃ for 9 hours, and then allow them to cool naturally to room temperature to obtain the calcined product.

[0047] S3. After thoroughly grinding the calcined product and passing it through a 300-mesh sieve, wash it three times with deionized water. Dry the centrifuged precipitate at 100℃ to obtain the product with the molecular formula YO3·NaAl. 0.5 O2:0.85Yb 3+ / 0.15Tm 3+ Rare earth-doped broadband short-wave infrared fluorescent materials.

[0048] YO3·NaAl 0.5 O2:0.85Yb 3+ / 0.15Tm 3+ The emission spectrum under 975nm excitation is as follows Figure 5 As shown, the emission wavelength range is ~1500nm-2100nm, and the half-width at half maximum (WHM) of the emission band reaches ~400nm.

[0049] Example 3

[0050] The rare earth-doped Gd of the present invention 1.948 O3·KAl 0.974 O2:0.05Yb 3+ / 0.002Tm 3+ (x=0.05, y=0.002, m=n=0.5) Broadband shortwave infrared fluorescent material and its preparation method, specifically including the following steps:

[0051] S1. Weigh out the following raw materials: 0.974 mmol Gd2O3, 0.50 mmol K2CO3, 0.487 mmol Al2O3, 0.025 mmol Yb2O3, and 0.001 mmol Tm2O3.

[0052] S2. After thoroughly mixing the weighed raw materials, calcine them in air at a rate of 8℃ / min to 1150℃ for 9 hours, and then allow them to cool naturally to room temperature to obtain the calcined product.

[0053] S3. After thoroughly grinding the calcined product and passing it through a 300-mesh sieve, wash it three times with deionized water. The centrifuged precipitate is then dried at 100°C to obtain the product with the molecular formula Gd. 1.948 O3·KAl 0.974 O2:0.05Yb 3+ / 0.002Tm 3+ Rare earth-doped broadband short-wave infrared fluorescent materials.

[0054] Gd 1.948 O3·KAl 0.974 O2:0.05Yb 3+ / 0.002Tm 3+ The emission spectrum under 975nm excitation is as follows Figure 6 As shown, the emission wavelength range is ~1500nm-2100nm, and the half-width at half maximum (WHM) of the emission band reaches ~400nm.

[0055] Comparative Example 1

[0056] Yb / Tm co-doped β-NaYF4 matrix material and its preparation method, specifically including the following steps:

[0057] S1. Weigh 1 mmol of rare earth acetate (Y / Yb / Tm = 78:20:1, mol) into a 100 mL round-bottom flask, then add 6 mL of oleic acid and 15 mL of octadecene. Seal the flask with vacuum silicone grease, evacuate and heat to 140 °C, then turn off the vacuum and purge with argon gas for protection. Maintain the temperature at 140 °C for 30 min to fully dissolve the rare earth acetate. Once the solution is clear and transparent, stop heating and allow it to cool to room temperature.

[0058] S2. During the cooling process, dissolve 4 mmol of ammonium fluoride and 2.5 mmol of sodium hydroxide in 10 mL of methanol, and then add them to the above rare earth oleate solution using a dropper. The solution is turbid. Stir at a constant temperature of 50°C for 30 min, then slowly raise the temperature to 65°C, turn off the argon gas, and start vacuuming for 10 min to completely remove the methanol.

[0059] S3. Next, the temperature is rapidly increased to 305℃ and held at this temperature for 90 minutes to allow the nanocrystals to complete the growth process. After the nanocrystals have grown, the nanocrystal-oleic acid mixture is removed, placed in a centrifuge tube, ethanol is added, the mixture is ultrasonically dispersed, centrifuged, and excess oleic acid is removed. This process is repeated three times. Finally, the nanocrystals are dried in a 60℃ oven to obtain β-NaYF4:Yb / Tm nanocrystals.

[0060] Transmission electron microscopy (TEM) images of β-NaYF4:Yb / Tm nanocrystals are shown below. Figure 7 As shown, from Figure 7 It can be seen that the β-NaYF4:Yb / Tm nanocrystals are spherical with a particle size of ~30 nm. This sample was prepared by a solvothermal method. Although the sample prepared by this method has a small particle size and uniform dispersion, the preparation process is complex, produces many by-products, and has a low yield.

[0061] The emission spectrum of β-NaYF4:Yb / Tm nanocrystals under 975 nm excitation is as follows: Figure 8As shown, from Figure 8 It can be seen that the emitted short-wave infrared light with a wavelength range of ~1600nm-2000nm has a half-width at half-maximum (FWHM) of ~170nm, which is much smaller than that of Example 1. This is because the β-NaYF4 crystal has high field symmetry and a single crystal field environment, resulting in Tm... 3+3 The F4 energy level did not split further, and the emission band did not undergo a blue shift or red shift. Therefore, the half-width at half maximum (FWHM) of the emission band of β-NaYF4:Yb / Tm is not as large as that of the present invention.

[0062] Comparative Example 2

[0063] Y 1.79 O3·LiAl 0.895 O2:0.21Yb 3+ Materials and their preparation methods; this sample does not contain the activator Tm. 3+ Specifically, it includes the following steps:

[0064] S1. Weigh out the following raw materials: Y2O3 0.895 mmol, Li2CO3 0.50 mmol, Al2O3 0.448 mmol, Yb2O3 0.105 mmol;

[0065] S2. After thoroughly mixing the weighed raw materials, calcine them in air at a rate of 8℃ / min to 1150℃ for 9 hours, and then allow them to cool naturally to room temperature to obtain the calcined product.

[0066] S3. After thoroughly grinding the calcined product and passing it through a 300-mesh sieve, wash it three times with deionized water. The centrifuged precipitate is then dried at 100°C to obtain the product with the molecular formula Y. 1.79 O3·LiAl 0.895 O2:0.21Yb 3+ The sample.

[0067] Y 1.79 O3·LiAl 0.895 O2:0.21Yb 3+ The emission spectrum under 975nm excitation is as follows Figure 9 As shown, from Figure 9 It can be seen that, due to the absence of the activator Tm 3+ Due to doping, the material has no emission peak.

[0068] Comparative Example 3

[0069] Y 1.79 The O3:0.2Yb / 0.01Tm material and its preparation method specifically include the following steps:

[0070] S1. Weigh out 0.895 mmol of Y2O3, 0.1 mmol of Yb2O3, and 0.005 mmol of Tm2O3.

[0071] S2. After thoroughly mixing the weighed raw materials, calcine them in air at a rate of 8℃ / min to 1150℃ for 9 hours, and then allow them to cool naturally to room temperature to obtain the calcined product.

[0072] S3. After thoroughly grinding the calcined product and passing it through a 300-mesh sieve, wash it three times with deionized water. The centrifuged precipitate is then dried at 100°C to obtain the product with the molecular formula Y. 1.79 The sample contains O3:0.2Yb / 0.01Tm.

[0073] Y 1.79 The emission spectrum of O3:0.2Yb / 0.01Tm under 975nm excitation is as follows: Figure 10 As shown, from Figure 10 It can be seen that, due to the absence of the secondary phase product LiAlO2, the emission band ranges from ~1600nm to 2000nm, and the half-width at half maximum (WHM) of the emission band is ~200nm.

[0074] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A rare earth doped broadband short wave infrared fluorescent material, characterized in that, M 2-2m(x+y) O3.NAl 1-n(x+y) O2.xYb 3+ / yTm 3+ , wherein 0.2<=x<=0.85, 0<y<=0.15, m+n=1; M is selected from Y 3+ , N is selected from Li + or Na + ; the rare earth doped broadband short wave infrared fluorescent material is a two-phase solid solution with M2O3 crystal phase as the main phase and NAlO2 crystal phase as the auxiliary phase.

2. The rare earth doped broadband short wave infrared fluorescent material of claim 1, wherein, The excitation wavelength of the rare earth doped broadband short-wave infrared fluorescent material is 950 nm-1100 nm.

3. The rare earth doped broadband short wave infrared fluorescent material of claim 1, wherein, The emission wavelength of the rare earth doped broadband short-wave infrared fluorescent material is 1500 nm-2100 nm.

4. The rare earth doped broadband short wave infrared fluorescent material of claim 1, wherein, The half-height width of the emission band of the rare earth doped broadband short-wave infrared fluorescent material is 350 nm-450 nm.

5. A method of producing the rare earth doped broadband short wave infrared fluorescent material according to any one of claims 1 to 4, characterized in that, The preparation method is a high-temperature solid-phase reaction method.

6. The method of claim 5, wherein the rare earth doped broadband short wave infrared fluorescent material is prepared by a method comprising: providing a precursor material comprising a rare earth dopant; and heating the precursor material to a temperature of 600 °C to 1,000 °C in the presence of a reducing atmosphere to form the rare earth doped broadband short wave infrared fluorescent material. The method comprises the following steps: taking raw materials according to the stoichiometric ratio of M, N, Al, Yb and Tm in the formula M 2-2m(x+y) O3.NAl 1-n(x+y) O2:xYb 3+ / yTm 3+ M2O3, N2CO3, Al2O3, Yb2O3 and Tm2O3 are mixed uniformly, calcined, ground, sieved, washed with water and dried to obtain the rare earth doped broadband short-wave infrared fluorescent material.

7. The method of claim 6, wherein the rare earth doped broadband short wave infrared fluorescent material is prepared by a method comprising: providing a precursor material comprising a rare earth dopant; and heating the precursor material to a temperature of about 600 °C to about 800 °C in the presence of a reducing atmosphere to form the rare earth doped broadband short wave infrared fluorescent material. The calcination is carried out at a rate of 5 ℃ / min-10 ℃ / min to 1100 ℃-1200 ℃ for 8 h-10 h.

8. The method of claim 6, wherein the rare earth doped broadband short wave infrared fluorescent material is prepared by a method comprising: providing a precursor material; and annealing the precursor material in a reducing atmosphere at a temperature of 600- 1000 °C for 1-24 hours. 8 The temperature of the drying is 60 ℃-120 ℃.

9. A short-wave infrared pc-LED device, characterized in that, The rare earth doped broadband short-wave infrared fluorescent material according to any one of claims 1-4 is encapsulated in an infrared light emitting diode to obtain the short-wave infrared pc-LED device.

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