Preparation and application of gallium germanate near-infrared luminescent material

Abstract

The application discloses a preparation method of a gallium germanate near-infrared luminescent material, and the luminescent material has a chemical formula of Ga 3+x‑y Al 3‑ x Ge2O 13 : y Cr 3+ According to a stoichiometric ratio of each raw material in the chemical formula, each raw material is weighed, Ga is introduced through an oxide, Al is introduced through an oxide or a hydroxide, Ge is introduced through an oxide, and Cr is introduced through an oxide or a nitrate; the raw materials are fully mixed and ground to obtain a raw material powder; the raw material powder is kept at a certain temperature in an air atmosphere, is cooled to room temperature in a furnace, is ground, and the near-infrared luminescent material is prepared. The preparation method can obtain the near-infrared luminescent material which has the advantages of a spectrum peak greater than 800 nm, adjustable spectrum, high luminescent efficiency (an external quantum efficiency is greater than 30%), good thermal stability (a residual luminescent intensity at 150 o C is greater than 60% at room temperature), can be efficiently excited by a blue light chip, and the like, can be applied to biological imaging, plant illumination, night monitoring and food detection, the preparation method is simple, no waste water and waste gas are discharged, and the preparation method is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to a near-infrared luminescent material, specifically a gallium germanate near-infrared luminescent material and its preparation method. Background Technology

[0002] In recent years, with the continuous development of near-infrared optics applications and the expanding market demand, near-infrared luminescent materials have received widespread attention from researchers and related industry professionals. Near-infrared phosphors, with their high luminous efficiency and high thermal stability, serve as key supporting materials for fluorescence-converting near-infrared light sources, demonstrating great application potential in fields such as plant growth, night vision lighting, security monitoring, non-destructive testing, iris recognition, and food composition analysis. Among numerous phosphor materials activated by different ions, Cr... 3+ It is relatively easy to achieve tunable broadband emission from deep red to NIR, and it exhibits strong broadband absorption in the visible spectrum, making it well-matched with blue LED chips. This has attracted particular attention from NIR phosphor researchers. Among reported phosphors, high-performance materials are currently limited to garnet systems. These materials have complex chemical compositions, require stringent synthesis conditions, and have expensive raw materials. Cr... 3+ The emission peaks produced in these materials are mostly between 700 and 780 nm (Light: Sci. Appl. 2020, 9, 86), which limits their applications and slows down their industrialization. Some materials with peak wavelengths greater than 800 nm, such as Ca2LaZr2Ga... 2.8 Al 0.2 O 12 :Cr 3+ peak wavelength λ em =820 nm, external quantum efficiency 23.5%, remnant luminescence intensity at 150 °C is 64% of that at room temperature (ACS Appl. Electron. Mater. 2022, 4, 643); Mg2Ge2O6:Cr 3+ peak wavelength λ em =844 nm, external quantum efficiency 28.5%, remnant luminescence intensity at 150 °C is only 33% of that at room temperature (J. Mater. Chem. C 2022, 10, 9232); LiGaP2O7:Cr 3+ peak wavelength λ em =846 nm, external quantum efficiency 28.3%, and residual luminescence intensity at 150℃ is only 20% of that at room temperature (LaserPhotonics Rev. 2021, 15, 2100227). In summary, existing material systems struggle to address the low efficiency and insufficient thermal stability of near-infrared materials with emission peak wavelengths greater than 800 nm, thus necessitating the development of Cr... 3+A novel, high-performance near-infrared luminescent material activated as a broadband near-infrared light source. Summary of the Invention

[0003] The present invention aims to provide a gallium germanate near-infrared luminescent material and its preparation method. The luminescent material has an emission spectrum peak greater than 800 nm, tunable spectrum, high luminous efficiency (external quantum efficiency exceeding 30%), good thermal stability (residual luminous intensity at 150℃ exceeds 65% of that at room temperature), and can be efficiently excited by blue light chips.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A gallium germanate near-infrared luminescent material, the chemical formula of which is Ga 3+x-y Al 3- x Ge2O 13 : y Cr 3+ , where 0≤ x ≤0.5, 0.008≤ y ≤0.02.

[0006] The preparation steps are as follows:

[0007] 1) According to the chemical formula of near-infrared luminescent materials Ga 3+x-y Al 3-x Ge2O 13 : y Cr 3+ The stoichiometric ratios of the various chemical components are based on the following raw materials:

[0008] Ga2O3 and GeO2;

[0009] Al2O3 or Al(OH)3;

[0010] Cr(NO3)3 or Cr2O3;

[0011] Mix all the raw materials and grind them thoroughly to obtain raw material powder.

[0012] 2) Place the raw material powder in a tube furnace and heat it to 1250℃~1450℃ at a heating rate of 5℃ / min. Calcinate for 4~6h and cool to room temperature to obtain the calcined product.

[0013] 3) The obtained roasted product is crushed, ground, graded and sieved to obtain the desired near-infrared phosphor.

[0014] Another object of the present invention is to provide a light-emitting device comprising a light source and a light-emitting material, wherein the light-emitting material is the aforementioned gallium germanate near-infrared light-emitting material, and the light source is a blue LED chip.

[0015] The obtained gallium germanate near-infrared luminescent material is glued onto the surface of a blue LED chip, and then a lens is installed to obtain a near-infrared LED luminescent device, which can be applied to bioimaging, plant lighting, night monitoring and food detection.

[0016] The preparation method of the present invention has the following advantages:

[0017] 1) The gallium germanate near-infrared fluorescent material provided by this invention emits a near-infrared spectrum with a peak wavelength of 800-860 nm that can be continuously varied under blue light excitation, and has high luminous efficiency (external quantum efficiency of more than 30%), which has potential commercial value.

[0018] 2) The obtained near-infrared luminescent material has good thermal stability, with the residual luminescence intensity at 150℃ exceeding 65% of that at room temperature;

[0019] 3) The preparation method is simple, pollution-free, wastewater and exhaust gas emissions are not produced, and there is no radioactivity. It will not cause harm to the environment, requires no protective atmosphere, is easy to operate, and is suitable for large-scale industrial production. Attached Figure Description

[0020] Figure 1 The XRD spectra of the near-infrared luminescent materials obtained in Examples 1-6 of this invention are shown.

[0021] Figure 2 The Ga prepared in Example 1 of this invention 2.992 Al3Ge2O 13 0.008Cr 3+ Excitation and emission spectra of the material.

[0022] Figure 3 The Ga obtained in Example 2 of this invention 2.988 Al3Ge2O 13 0.012Cr 3+ Excitation and emission spectra of the material.

[0023] Figure 4 The Ga obtained in Example 3 of this invention 2.984 Al3Ge2O 13 0.016Cr 3+ Excitation and emission spectra of the material.

[0024] Figure 5 The Ga obtained in Example 4 of this invention 2.98 Al3Ge2O13 0.02Cr 3+ Excitation and emission spectra of the material.

[0025] Figure 6 The Ga obtained in Example 5 of this invention 3.49 Al 2.5 Ge2O 13 0.01Cr 3+ Excitation and emission spectra of the material.

[0026] Figure 7 The Ga obtained in Example 6 of this invention 3.485 Al 2.5 Ge2O 13 0.015Cr 3+ Excitation and emission spectra of the material.

[0027] Figure 8 This is a schematic diagram of the structure of the light-emitting device provided by the present invention.

[0028] Figure reference numerals: 1-LED chip, 2-heat sink, 3-base, 4-adhesive layer, 5-lens. Detailed Implementation

[0029] The present invention will be further explained and described below with reference to specific embodiments.

[0030] Example 1

[0031] Press Ga 2.992 Al3Ge2O 13 0.008Cr 3+ Based on the stoichiometric ratio shown in the molecular formula, weigh 0.43585 g of Ga₂O₃, 0.23771 g of Al₂O₃, 0.32528 g of GeO₂, and 0.00094 g of Cr₂O₃, mix and grind thoroughly to obtain raw material powder; transfer to an alumina crucible, heat to 1400℃ in air at a heating rate of 5℃ / min, hold at that temperature for 5 h, cool to room temperature with the furnace to obtain calcined material, grind, and obtain near-infrared luminescent material Ga 2.992 Al3Ge2O 13 0.008Cr 3+ .

[0032] Figure 1 The X-ray diffraction (XRD) patterns of the materials prepared in Examples 1-6, and Al6Ge2O 13 Comparison with the standard cards shows that the diffraction peaks of all samples match the standard cards very well, with no extraneous impurity phases, and an overall trend towards a smaller angle of shift. This is attributed to the larger radius of Ga. 3+ Replace Al 3+The subsequent lattice expansion proves that all materials are Ga3Al3Ge2O 13 Single-phase sample. Figure 2 The excitation and emission spectra of the material prepared in Example 1 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 807 nm, which is attributed to Cr. 3+ The characteristic emission indicates that the material can emit light in the near-infrared region when excited by a suitable light source. Its excitation spectrum covers the range from near-ultraviolet to red light, which can be effectively matched with blue light chips.

[0033] Example 2

[0034] Press Ga 2.988 Al3Ge2O 13 0.012Cr 3+ According to the stoichiometric ratio shown in the molecular formula, 0.43526 g of Ga₂O₃, 0.23771 g of Al₂O₃, 0.32528 g of GeO₂, and 0.00142 g of Cr₂O₃ were weighed, thoroughly mixed and ground to obtain raw material powder; transferred to an alumina crucible, heated to 1400℃ at a heating rate of 5℃ / min in air atmosphere, held at that temperature for 5h, and cooled to room temperature with the furnace to obtain calcined material, which was then ground to obtain near-infrared luminescent material Ga. 2.988 Al3Ge2O 13 0.012Cr 3+ .

[0035] Figure 3 The excitation and emission spectra of the material prepared in Example 2 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 816 nm, which is attributed to Cr. 3+ Its characteristic emission, with an excitation spectrum covering the range from near ultraviolet to red light, can be effectively matched with blue light chips.

[0036] Example 3

[0037] Press Ga 2.984 Al3Ge2O 13 0.016Cr 3+ Based on the stoichiometric ratio shown in the molecular formula, 0.43468 g of Ga₂O₃, 0.23771 g of Al₂O₃, 0.32528 g of GeO₂, and 0.00189 g of Cr₂O₃ were weighed, thoroughly mixed, and ground to obtain raw material powder. The powder was transferred to an alumina crucible and heated to 1350℃ at a rate of 5℃ / min in air, held for 5 hours, and then cooled to room temperature in the furnace to obtain calcined material. This calcined material was then ground to obtain near-infrared luminescent material Ga. 2.984 Al3Ge2O 130.016Cr 3+ .

[0038] Figure 4 The excitation and emission spectra of the material prepared in Example 3 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 832 nm, which is attributed to Cr. 3+ Its characteristic emission, with an excitation spectrum covering the range from near ultraviolet to red light, can be effectively matched with blue light chips.

[0039] Example 4

[0040] Press Ga 2.98 Al3Ge2O 13 0.02Cr 3+ Based on the stoichiometric ratio shown in the molecular formula, weigh 0.43410 g of Ga₂O₃, 0.36372 g of Al(OH)₃, 0.32528 g of GeO₂, and 0.00740 g of Cr(NO₃)₃, mix and grind them thoroughly to obtain raw material powder; transfer the powder to an alumina crucible, heat it to 1350℃ in air at a heating rate of 5℃ / min, hold it at that temperature for 5 hours, and then cool it to room temperature with the furnace to obtain calcined material. Grind the calcined material to obtain near-infrared luminescent material Ga. 2.98 Al3Ge2O 13 0.02Cr 3+ .

[0041] Figure 5 The excitation and emission spectra of the material prepared in Example 4 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 845 nm, which is attributed to Cr. 3+ Its characteristic emission, with an excitation spectrum covering the range from near ultraviolet to red light, can be effectively matched with blue light chips.

[0042] Example 5

[0043] Press Ga 3.49 Al 2.5 Ge2O 13 0.01Cr 3+ According to the stoichiometric ratio shown in the molecular formula, 0.50839 g of Ga₂O₃, 0.30310 g of Al(OH)₃, 0.32528 g of GeO₂, and 0.00118 g of Cr₂O₃ were weighed, thoroughly mixed and ground to obtain raw material powder; transferred to an alumina crucible, heated to 1400℃ at a heating rate of 5℃ / min in air atmosphere, held at that temperature for 5h, and cooled to room temperature with the furnace to obtain calcined material, which was then ground to obtain near-infrared luminescent material Ga. 3.49 Al 2.5 Ge2O13 0.01Cr 3+ .

[0044] Figure 6 The excitation and emission spectra of the material prepared in Example 5 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 825 nm, which is attributed to Cr. 3+ Its characteristic emission, with an excitation spectrum covering the range from near ultraviolet to red light, can be effectively matched with blue light chips.

[0045] Example 6

[0046] Press Ga 3.485 Al 2.5 Ge2O 13 0.015Cr 3+ Based on the stoichiometric ratio shown in the molecular formula, weigh 0.50766 g of Ga₂O₃, 0.30310 g of Al(OH)₃, 0.32528 g of GeO₂, and 0.00177 g of Cr₂O₃, mix and grind thoroughly to obtain raw material powder; transfer to an alumina crucible, heat to 1400℃ in air at a heating rate of 5℃ / min, hold at that temperature for 5 h, cool to room temperature with the furnace to obtain calcined material, grind, and obtain near-infrared luminescent material Ga 3.485 Al 2.5 Ge2O 13 0.015Cr 3+ .

[0047] Figure 7 The excitation and emission spectra of the material prepared in Example 6 show that the emission wavelength range is 650 nm to 1000 nm, and the emission peak is located at 859 nm, which is attributed to Cr. 3+ Its characteristic emission, with an excitation spectrum covering the range from near ultraviolet to red light, can be effectively matched with blue light chips.

[0048] Table 1. Residual luminescence intensity and external quantum efficiency of the phosphors in Examples 1-6 at 150°C.

[0049]

[0050] In view of the excellent luminescence intensity and external quantum efficiency of the phosphors prepared in Examples 1-6 above, the present invention also provides a light-emitting device prepared using the near-infrared luminescent material prepared in Example 1, the structure of which is as follows: Figure 8As shown, the light-emitting device includes an LED chip 1, a heat sink 2, a base 3, an adhesive layer 4, and a lens 5. The LED chip 1 is fixed to the base 3 by the heat sink 2. Adhesive and light-emitting material are coated on the LED chip 1 to form the adhesive layer 4, and the lens 5 is disposed on the adhesive layer 4. Preferably, the LED chip 1 is a blue LED chip. The light-emitting device provided by this invention can be applied to many fields such as biometrics, 3D sensing, food / medical testing, agricultural production, or bioimaging.

Claims

1. A gallium germanate near-infrared luminescent material, characterized in that, The chemical formula for this near-infrared luminescent material is Ga. 3+x-y Al 3-x Ge2O 13 : y Cr 3+ , where 0≤ x ≤0.5, 0.008≤ y ≤0.02; The luminescent material, when excited by blue light, has a peak wavelength of emission spectrum greater than 800 nm, and its luminescence intensity at 150℃ remains more than 65% of that at room temperature.

2. A method for preparing the gallium germanate near-infrared luminescent material as described in claim 1, characterized in that, Includes the following steps: 1) According to the chemical formula Ga 3+x-y Al 3-x Ge2O 13 : y Cr 3+ Based on the stoichiometric ratio of each element, weigh the following raw materials respectively: Ga2O3 and GeO2; Al2O3 or Al(OH)3; Cr(NO3)3 or Cr2O3; Mix all the raw materials and grind them thoroughly to obtain raw material powder; 2) Place the raw material powder in a tube furnace and heat it to 1250℃~1450℃ at a heating rate of 5℃ / min. Calcinate for 4~6 hours and cool to room temperature to obtain the calcined product. 3) The obtained roasted product is crushed, ground, graded and sieved to obtain the desired near-infrared phosphor.

3. A light-emitting device, comprising a light source and a light-emitting material, characterized in that, The luminescent material is the near-infrared luminescent material as described in claim 1, and the light source is a blue LED chip.

4. The application of the light-emitting device as described in claim 3 in bioimaging, plant illumination, nighttime monitoring, and food detection.

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