Near-infrared fluorescent powder and preparation method and application thereof

Abstract

The application discloses a near-infrared fluorescent powder, a preparation method and application thereof, and has a chemical general formula of Ba5La3Mg 1‑x MO 15 :Cr x ; wherein M is Al and / or Ga; 0.001<=x<=0.07, the near-infrared fluorescent powder has a brand-new crystal structure, takes Cr 3+ as an activator, the fluorescent powder can be excited by light in a wavelength range of 350-800 nm to emit near-infrared light with a peak wavelength in a range of 700-1400 nm, so that the near-infrared fluorescent powder can absorb light in the ultraviolet and visible bands to be converted into near-infrared light. Meanwhile, the near-infrared fluorescent powder has the advantages of simple preparation method, stable chemical performance, high efficiency and being beneficial to industrial production, and shows an application prospect in NIR-LED (infrared light-emitting diode) devices, and can be used as a high-efficiency, heat-stable broadband NIR-LED light source, and shows practical potential in night vision and nondestructive testing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of luminescent materials, in particular to a near-infrared fluorescent powder and a preparation method and application thereof. BACKGROUND

[0002] With the popularity of smart phones and wearable devices, small size and adjustable wide near-infrared light sources are widely used in night vision, daily food, health monitoring and rapid analysis fields. In recent years, near-infrared emitting phosphor converted LEDs (pc-LEDs) have attracted much interest due to their small size, wide tunable emission, high efficiency and other advantages (Reference 1: Zhenwei J, Chenxu Y, Liu Y, et al. Strategies to approach high performance in Cr 3+ -doped phosphors for high-power NIR-LED light sources [J]. Light: Science and Applications, 2020, 9(1).

[0003] Although different types of near-infrared fluorescent powders have been reported, their emission coverage is limited to the short-wave direction (λ max <800nm; FWHM <150nm), but there are also fluorescent powders with emission wavelength λ max >900nm reported, such as (Ga, Sc, In)(Ta, Nb)O4:Cr 3+ reported in reference 2, LiIn 1-x Sc x GeO4 reported in reference 3, and CaSc 1-x Mg x Al 1-x Si 1+x O6:Cr 3+ etc., but due to the long-wavelength emission is usually caused by a large Stokes shift, through the thermal activation of the ground state and the excited state potential surface, which will promote the generation of non-radiative transition; resulting in these long-wave near-infrared fluorescent powders generally have low quantum efficiency, serious thermal quenching and other problems (Reference: 2, Zhang Q, Liu D, Dang P, et al. Two selective sites control of Cr 3+Huang S, Yan Y, Shang M, et al. Super Broadband Near-Infrared Solid Solution Phosphors with Adjustable Peak Wavelengths from 1165 to 875 nm for NIR Spectroscopy Applications[J]. Advanced Optical Materials, 2023, 11(5): 2202291; 4, Wen D, Liu H, Guo Y, et al. Disorder-Order Conversion-Induced Enhancement of Thermal Stability of Pyroxene Near-Infrared Phosphors for Light-Emitting Diodes[J]. Angewandte Chemie, 2022, 134(28): e202204411.) In recent years, the disordered lattice structure has gradually entered people's field of vision, and its characteristics are the random distribution of different atoms at a given crystal position, which can effectively create multiple local coordinated environments around the activator, thus being conducive to the uneven broadening of the emission band.

[0004] Therefore, it is particularly important and very meaningful and promising to develop related near-infrared fluorescent powder with disordered lattice structure. SUMMARY

[0005] The purpose of the present application is to solve the problems of low quantum efficiency, serious thermal quenching and the like of the existing long-wave near-infrared (λ max >900nm) and to provide a near-infrared fluorescent powder and a preparation method and application thereof, which has a brand-new crystal structure, and Cr 3+As an activator, the fluorescent powder can be excited by light in a wavelength range of 350-800 nm to emit near-infrared light in a wavelength range of 700-1400 nm, so that the near-infrared fluorescent powder can convert light in the ultraviolet and visible bands into near-infrared light. Meanwhile, the near-infrared fluorescent powder provided by the application has the advantages of simple preparation method, stable chemical properties, high efficiency and being conducive to industrialized production, and shows application prospects of the near-infrared fluorescent powder in NIR-LED (infrared light-emitting diode) devices. The near-infrared fluorescent powder can be used as a high-efficiency, heat-stable broadband NIR-LED light source, and shows practical potential in night vision and nondestructive testing.

[0006] To achieve the above-mentioned purpose, the first aspect of the application provides a near-infrared fluorescent powder, the chemical formula of the near-infrared fluorescent powder is as follows: Ba5La3Mg 1-x MO 15 :Cr x ; wherein,

[0007] M is Al and / or Ga;

[0008] 0.001≤x≤0.07.

[0009] The second aspect of the application provides a preparation method of a near-infrared fluorescent powder, the preparation method comprises the following steps: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, sintering, and obtaining the near-infrared fluorescent powder; wherein,

[0010] The M precursor is an Al precursor and / or a Ga precursor.

[0011] The third aspect of the application provides a preparation method of a near-infrared fluorescent powder, the preparation method comprises the following steps: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, first sintering, grinding, second sintering, and obtaining the near-infrared fluorescent powder; wherein,

[0012] The M precursor is an Al precursor and / or a Ga precursor.

[0013] The fourth aspect of the application provides an application of the above-mentioned near-infrared fluorescent powder in night vision, infrared light-emitting diode, daily food, health detection and rapid analysis.

[0014] In the above technical solution, the near-infrared fluorescent powder of the application takes a disordered structure as a matrix, Cr 3+ as an activator, has a non-uniform broadening emission band of 700-1400 nm, and the peak value is at 925 nm. At a similar wavelength, the luminescent intensity at 423 K can maintain 61% of that at room temperature, which is better than the currently reported Cr 3+ activated broadband near-infrared fluorescent powder, and can solve the problems of the current long-wave near-infrared (λmax 900nm) quantum efficiency is low, thermal quenching is serious and other problems; thereby promoting the application of near-infrared oxide fluorescent powder in night vision, daily food, health detection and rapid analysis and the like.

[0015] In addition, the near-infrared fluorescent powder preparation method is simple and easy to operate, high in efficiency and conducive to industrialized production, and is more conducive to further application and popularization of the near-infrared fluorescent powder.

[0016] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the present application, but do not constitute a limitation on the present application. In the drawings:

[0018] Figure 1 A crystal structure diagram of the near-infrared fluorescent powder B1 prepared for Example 1;

[0019] Figure 2 A crystal structure diagram of the near-infrared fluorescent powder B2 prepared for Example 2;

[0020] Figure 3 The near-infrared fluorescent powder Ba5La3MgM3O 15 (M is one or more elements of Al, Ga) crystal X-ray powder diffraction peak pattern;

[0021] Figure 4 A result diagram of X-ray powder diffraction of the near-infrared fluorescent powder B3-B4 prepared for Examples 3-4;

[0022] Figure 5 A result diagram of X-ray powder diffraction of the near-infrared fluorescent powder B3, B5 and B10 prepared for Example 3, Example 5 and Example 10;

[0023] Figure 6 An element distribution mapping picture of the near-infrared fluorescent powder B3 prepared for Example 3;

[0024] Figure 7 A diagram of excitation spectrum and emission spectrum of the near-infrared fluorescent powder B3 prepared for Example 3;

[0025] Figure 8 A diagram of excitation spectrum and emission spectrum of the near-infrared fluorescent powder B4 prepared for Example 4;

[0026] Figure 9The emission spectra of near-infrared phosphors B3, B5-B7 and B10 prepared in Examples 3, 5-7 and 10 under excitation wavelength of 468 nm are shown.

[0027] Figure 10 This is a graph showing the change in luminescence intensity of the near-infrared phosphor B5 prepared in Example 5 as a function of temperature under excitation wavelength of 468 nm.

[0028] Figure 11 This is the application of near-infrared phosphor B5 prepared in Example 5 under near-infrared light source irradiation in night vision;

[0029] Figure 12 This describes the application of near-infrared phosphor B5 prepared in Example 5 in biological tissue monitoring and transmission under near-infrared light source irradiation. Detailed Implementation

[0030] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] The first aspect of this invention provides a near-infrared phosphor with the general chemical formula: Ba5La3Mg 1-x MO 15 :Cr x ;in,

[0033] M is Al and / or Ga;

[0034] 0.001≤x≤0.07.

[0035] The near-infrared phosphor of this invention has a novel chemical composition, using a disordered structure as the matrix, and Cr 3+ As an activator, it exhibits a non-uniformly broadened emission band of 700-1400 nm, with a peak at 925 nm. At similar wavelengths, its luminescence thermal stability is such that its luminescence intensity at 423 K can be maintained at 61% of that at room temperature, which is superior to currently reported Cr... 3+ Activated broadband near-infrared phosphors can solve the problems of existing long-wave near-infrared (λ) phosphors. maxThe problems of low quantum efficiency, serious thermal quenching and the like of the near-infrared oxide fluorescent powder are solved, and the application of the near-infrared oxide fluorescent powder in night vision, daily food, health detection and rapid analysis is promoted.

[0036] In the preferred embodiment of the present application, the excitation wavelength of the near-infrared fluorescent powder is 350-800 nm, and the emission peak is 700-1400 nm.

[0037] The second aspect of the present application provides a preparation method of the near-infrared fluorescent powder, which comprises the following steps: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, and sintering to obtain the near-infrared fluorescent powder; wherein,

[0038] The M precursor is an Al precursor and / or a Ga precursor.

[0039] The preparation method provided by the present application is simple in operation, high in efficiency and conducive to industrialized production, and is more conducive to the further application and promotion of the material.

[0040] In the preferred embodiment of the present application, in order to make the sintered near-infrared fluorescent powder have higher fluorescent quantum efficiency, the molar ratio of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is 5:3:1-x:3:x, wherein 0.001≤x≤0.07, the Ba precursor is calculated by Ba atoms, the La precursor is calculated by La atoms, the Mg precursor is calculated by Mg atoms, the M precursor is calculated by M atoms, and the Cr precursor is calculated by Cr atoms.

[0041] In the preferred embodiment of the present application, in order to avoid the light emission quenching caused by impurities of raw materials and obtain a high-quality phase structure, the purity of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is not less than 99.9%.

[0042] In the preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Ba precursor is selected from one or two or more of carbonates of Ba, oxides of Ba, oxalates of Ba and nitrates of Ba.

[0043] In the preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the La precursor is selected from one or two or more of carbonates of La, oxides of La, oxalates of La and nitrates of La.

[0044] In the preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Mg precursor is selected from one or two or more of carbonates of Mg, oxides of Mg, oxalates of Mg and nitrates of Mg.

[0045] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, when the M precursor is an Al precursor, the Al precursor is selected from one or more of an Al carbonate, an Al oxide and an Al nitrate.

[0046] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, when the M precursor is a Ga precursor, the Ga precursor is selected from a Ga oxide and / or a Ga nitrate.

[0047] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Cr precursor is selected from one or more of a Cr carbonate, a Cr oxide and a Cr nitrate.

[0048] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the sintering conditions include: in a reducing atmosphere, the temperature is 1400-1600℃, the heating rate is 1-5℃ / min, and the time is 4-8h.

[0049] In a preferred embodiment of the present application, in order to avoid the experimental danger brought by pure hydrogen as much as possible, the reducing atmosphere is a mixed atmosphere of hydrogen and argon and / or a mixed atmosphere of hydrogen and nitrogen.

[0050] In a preferred embodiment of the present application, in order to avoid the oxidation of Cr 3+ to a high valence state and affect the luminous intensity, the gas content ratio of hydrogen and argon is 1:5-20.

[0051] In a preferred embodiment of the present application, in order to avoid the oxidation of Cr 3+ to a high valence state and affect the luminous intensity, the gas content ratio of hydrogen and nitrogen is 1:5-20.

[0052] A third aspect of the present application provides a preparation method of a near-infrared fluorescent powder, which comprises: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, first sintering, grinding, second sintering, to obtain a near-infrared fluorescent powder; wherein,

[0053] The M precursor is an Al precursor and / or a Ga precursor.

[0054] In a preferred embodiment of the present application, in order to obtain the sintered fluorescent powder as the target phase, the molar ratio of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is 5:3:1-x:3:x, wherein 0.001≤x≤0.07, the Ba precursor is in terms of Ba atoms, the La precursor is in terms of La atoms, the Mg precursor is in terms of Mg atoms, the M precursor is in terms of M atoms, and the Cr precursor is in terms of Cr atoms.

[0055] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the purity of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is not less than 99.9%.

[0056] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Ba precursor is selected from one or more than two of carbonates of Ba, oxides of Ba, oxalates of Ba and nitrates of Ba.

[0057] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the La precursor is selected from one or more than two of carbonates of La, oxides of La, oxalates of La and nitrates of La.

[0058] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Mg precursor is selected from one or more than two of carbonates of Mg, oxides of Mg, oxalates of Mg and nitrates of Mg.

[0059] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, when the M precursor is an Al precursor, the Al precursor is selected from one or more than two of carbonates of Al, oxides of Al and nitrates of Al.

[0060] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, when the M precursor is a Ga precursor, the Ga precursor is selected from oxides of Ga and / or nitrates of Ga.

[0061] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the Cr precursor is selected from one or more than two of carbonates of Cr, oxides of Cr and nitrates of Cr.

[0062] In a preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the first sintering condition comprises: in an air atmosphere, the temperature is 600-1000℃, the heating rate is 4-8℃ / min, and the time is 8-12h.

[0063] In the preferred embodiment of the present application, in order to ensure the phase purity of the near-infrared fluorescent powder, the second sintering conditions include: in a reducing atmosphere, the temperature is 1400-1600℃, the heating rate is 1-5℃ / min, and the time is 4-8h.

[0064] In the preferred embodiment of the present application, in order to avoid the experimental danger caused by pure hydrogen, the reducing atmosphere is a mixed atmosphere of hydrogen and argon and / or a mixed atmosphere of hydrogen and nitrogen.

[0065] In the preferred embodiment of the present application, in order to avoid the oxidation of Cr 3+ to high valence state and affect the luminous intensity, the gas content ratio of hydrogen and argon is 1:5-20.

[0066] In the preferred embodiment of the present application, in order to avoid the oxidation of Cr 3+ to high valence state and affect the quantum efficiency, the gas content ratio of hydrogen and nitrogen is 1:5-20.

[0067] In the preferred embodiment of the present application, in order to make the high-temperature solid-phase reaction more sufficient and further improve the luminous intensity as charge compensation, the preparation method further comprises adding a fluxing agent during the first sintering.

[0068] In the preferred embodiment of the present application, in order to avoid the generation of impurities caused by excessive fluxing agent, the amount of the fluxing agent is 0.5%-2% of the total mass of the precursor.

[0069] The fourth aspect of the present application provides an application of the above-mentioned near-infrared fluorescent powder in night vision, infrared light-emitting diode, daily food, health detection and rapid analysis.

[0070] The present application will be described in detail below through examples. In the following examples, the drugs and reagents are all conventional commercially available products.

[0071] Example 1

[0072] (1) BaCO3 (analytical pure), La2O3 (analytical pure), MgO (analytical pure) and Al2O3 (analytical pure) were weighed according to the molar ratio of 5:1.5:1:1.5, ground and mixed uniformly, dried, and then loaded into a corundum crucible in a muffle furnace, the temperature was raised to 800℃ at a rate of 6℃ / min, sintered for 10 hours, and then cooled to room temperature at a rate of 6℃ / min, to obtain an oxide fluorescent powder precursor salt;

[0073] (2) The oxide fluorescent powder precursor salt is ground and mixed uniformly, loaded into a corundum crucible, and placed in a high-temperature furnace. The H2 / Ar mixed gas has a gas flow rate of 100 mL / min and a gas content ratio of H2:Ar=10:90. The temperature is raised to 1450°C at a rate of 3°C / min, sintered for 6 hours, and then cooled to room temperature at a rate of 3°C / min. After being taken out, the mixture is ground to obtain a near-infrared fluorescent powder Ba5La3MgAl3O 15 , denoted as B1.

[0074] Example 2

[0075] The method described in Example 1 is implemented, except that Al2O3(analytically pure) in step (1) is replaced by Ga2O3(analytically pure) to obtain a near-infrared fluorescent powder Ba5La3MgGa3O 15 , denoted as B2.

[0076] Example 3

[0077] (1) BaCO3(analytically pure), La2O3(analytically pure), MgO(analytically pure), Al2O3(analytically pure), and Cr2O3(analytically pure) are weighed according to the molar ratio of 5:1.5:0.96:1.5:0.02, ground and mixed uniformly, dried, and then loaded into a corundum crucible in a muffle furnace. The temperature is raised to 800°C at a rate of 6°C / min, sintered for 10 hours, and then cooled to room temperature at a rate of 6°C / min to obtain a Cr 3+ doped oxide fluorescent powder precursor salt;

[0078] (2) The Cr 3+ doped oxide fluorescent powder precursor salt is ground and mixed uniformly, loaded into a corundum crucible, and placed in a high-temperature furnace. The H2 / Ar mixed gas has a gas flow rate of 100 mL / min and a gas content ratio of H2:Ar=10:90. The temperature is raised to 1450°C at a rate of 3°C / min, sintered for 6 hours, and then cooled to room temperature at a rate of 3°C / min. After being taken out, the mixture is ground to obtain a near-infrared fluorescent powder, denoted as B3.

[0079] Example 4

[0080] The method described in Example 3 is implemented, except that Al2O3(analytically pure) in step (1) is replaced by Ga2O3(analytically pure) to obtain a near-infrared fluorescent powder, denoted as B4.

[0081] Example 5

[0082] The method described in Example 3 is implemented, except that 1% of Li2CO3 based on the total weight of the raw materials is added before being ground and mixed uniformly in step (1) to obtain a near-infrared fluorescent powder, denoted as B5.

[0083] Example 6

[0084] The method of Example 3 was implemented, except that 1% of Na2CO3 by weight of the total raw materials was added before grinding and mixing in step (1), to obtain a near-infrared fluorescent powder, denoted as B6.

[0085] Example 7

[0086] The method of Example 3 was implemented, except that 1% of K2CO3 by weight of the total raw materials was added before grinding and mixing in step (1), to obtain a near-infrared fluorescent powder, denoted as B7.

[0087] Example 8

[0088] The method of Example 3 was implemented, except that the H2 / Ar mixed gas with a gas content ratio of H2:Ar = 10:90 was replaced by H2 / N2 mixed gas with a gas content ratio of H2:N2 = 10:90 in step (2), to obtain a near-infrared fluorescent powder, denoted as B8.

[0089] Example 9

[0090] The method of Example 3 was implemented, except that the H2 / Ar mixed gas with a gas content ratio of H2:Ar = 10:90 was replaced by H2 / Ar mixed gas with a gas content ratio of H2:Ar = 5:95 in step (2), to obtain a near-infrared fluorescent powder, denoted as B9.

[0091] Example 10

[0092] The method of Example 3 was implemented, except that step (1) was omitted, and the crucible containing the mixed and uniform raw materials was directly placed in a high-temperature furnace, the temperature was raised to 1450°C at a rate of 3°C / min in H2 / Ar mixed gas with a gas flow rate of 100 mL / min and a gas content ratio of H2:Ar = 10:90, sintered for 6 hours, and then cooled to room temperature at a rate of 3°C / min, after which the near-infrared fluorescent powder was obtained by grinding, denoted as B10.

[0093] Detection Example 1

[0094] The near-infrared fluorescent powders B1-B2 prepared in Examples 1-2 were first measured by X-ray powder diffraction, and then the crystal structure was calculated using structure analysis software (GSAS-II), as shown in Figures 1-2 The crystal structure data obtained are shown in Table 1-2,

[0095] Table 1-2 shows the crystal structure data of the near-infrared fluorescent powders Ba5La3MgAl3O 15The crystal system, space group, lattice constant, atomic species, and atomic position of the crystal and Ba5La3MgGa3O crystal can be determined using the data, and the shape of the lattice and the arrangement of atoms in the lattice can be determined.

[0096] Table 1

[0097]

[0098] In Table 1, the lattice constants a, b, and c represent the near-infrared fluorescent powder Ba5La3MgAl3O 15 The axis length of the unit cell of the crystal, and α, β, and γ represent the angles between the axes of the unit cell. The atomic coordinates x, y, and z represent the positions of the atoms in the unit cell, with values between 0 and 1.

[0099] As can be seen from Table 1, in the Ba5La3MgAl3O 15 Each atom of Ba, La, Mg, Al, and O exists in the crystal, and Ba and La exist in one same position (Ba(1), La(1)); Ba exists in three same positions (Ba(2) to Ba(4)); Mg exists in one same position (Mg(1)); Al exists in one same position (Al(1)); and O exists in four different positions.

[0100] As can be seen from Table 1, in the Ba5La3MgAl3O Figure 1 The near-infrared fluorescent powder Ba5La3MgAl3O 15 As can be seen from Table 1, in the Ba5La3MgAl3O 15 In the Ba5La3MgAl3O crystal, Al(1) is an AlO4 tetrahedron, Mg(1) is an MgO6 octahedron, Ba(1) / La(1) occupies the same position as a Ba / LaO8 octahedron, Ba(2) is a BaO10 decahedron, Ba(3) is a BaO6 octahedron, Ba(4) is a BaO12 dodecahedron, and the unmarked atoms are all O atoms in the crystal structure, i.e., Ba5La3MgAl3O 15 The Ba5La3MgAl3O crystal belongs to the hexagonal crystal system and belongs to the P63mc group (the 168th space group of International Tables for Crystallography).

[0101] It should be noted that the so-called activating element Cr, which is responsible for luminescence in the crystal, is introduced into the crystal in the form of replacing a part of Mg.

[0102] Table 2

[0103]

[0104]

[0105] In the above Table 2, the lattice constants a, b, c represent the near-infrared fluorescent powder Ba5La3MgGa3O 15 The axis length of the unit cell of the crystal, a, b, g represents the angle between the axes of the unit cell, and the atomic coordinates x, y, z represent the position of each atom in the unit cell with a value of 0-1 as the unit of the unit cell.

[0106] As can be seen from Table 2, in the Ba5La3MgGa3O 15 Each atom of Ba, La, Mg, Ga, and O exists in the crystal, and Ba and La exist in one same position (Ba(1), La(1)); Ba exists in three same positions (Ba(2)-Ba(4)); Mg exists in one same position (Mg(1)), Ga exists in one same position (Ga(1)); and O exists in four different positions.

[0107] As can be seen from Table 2, in the Ba5La3MgGa3O Figure 2 The near-infrared fluorescent powder Ba5La3MgGa3O 15 As can be seen from the crystal structure diagram of the crystal, in the Ba5La3MgGa3O 15 In the Ba5La3MgGa3O crystal, Ga(1) is GaO4 tetrahedron, Mg(1) is MgO6 hexahedron, Ba(1) / La(1) occupies the same position as Ba / LaO8 octahedron, Ba(2) is BaO10 decahedron, Ba(3) is BaO6 hexahedron, Ba(4) is BaO12 dodecahedron, and the unmarked atoms are all O atoms in the crystal structure, i.e., Ba5La3MgGa3O 15 The crystal belongs to the hexagonal system and belongs to the P63mc group (the 168th space group of International Tables for Crystallography).

[0108] It should be noted that in this crystal, the so-called activating element Cr, which undertakes luminescence, is introduced into the crystal in the form of replacing a part of Mg.

[0109] Detection Example 2

[0110] The near-infrared fluorescent powders B3-B10 prepared in Examples 3-10 were analyzed by X-ray powder diffraction, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3-B4 prepared in Examples 3-4 are shown in FIG. 2, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3, B5, and B10 prepared in Example 3, Example 5, and Example 10 are shown in FIG. 3 and FIG. 4, respectively. Figure 4 The near-infrared fluorescent powders B3-B10 prepared in Examples 3-10 were analyzed by X-ray powder diffraction, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3-B4 prepared in Examples 3-4 are shown in FIG. 2, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3, B5, and B10 prepared in Example 3, Example 5, and Example 10 are shown in FIG. 3 and FIG. 4, respectively. Figure 5 The near-infrared fluorescent powders B3-B10 prepared in Examples 3-10 were analyzed by X-ray powder diffraction, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3-B4 prepared in Examples 3-4 are shown in FIG. 2, and the results of X-ray powder diffraction of the near-infrared fluorescent powders B3, B5, and B10 prepared in Example 3, Example 5, and Example 10 are shown in FIG. 3 and FIG. 4, respectively.

[0111] As can be seen from Table 2, in the Ba5La3MgGa3O Figure 4It can be seen that the X-ray powder diffraction patterns of the near-infrared phosphors B3-B4 prepared in Examples 3-4 are similar to those of the near-infrared phosphors B3-B4 prepared in Examples 3-4. Figure 3 The near-infrared phosphor Ba5La3MgM3O prepared in Examples 1-2 is shown in Tables 1 and 2, calculated based on the values ​​shown. 15 Compared to the peak pattern of X-ray powder diffraction of the crystal (M is one or more elements in Al and Ga), there is a slight increase in diffraction angle, and no obvious impurity peaks were observed, thus confirming the reliability of the near-infrared phosphor of the present invention synthesized by the high-temperature solid-state method.

[0112] Depend on Figure 5 It can be seen that the X-ray powder diffraction peaks of the near-infrared phosphors B5 and B10 prepared in Examples 5 and 10 did not show obvious impurity peaks compared with the peak pattern of the X-ray powder diffraction in Example 3, thus confirming the reliability of the near-infrared phosphors obtained in Examples 5 and 10.

[0113] It should be noted that, as a crystal with an unknown crystal structure, it is unclear whether it possesses properties similar to the described Ba5La3MgAl3O. 15 A simple method for determining identical crystal structures can be used as follows: For a crystal whose crystal structure is unknown and is the object of determination, the measured position (2θ) of the X-ray diffraction peak is compared with... Figure 3 The near-infrared phosphor Ba5La3MgM3O prepared in Examples 1-2 is shown in Tables 1 and 2, calculated based on the values ​​shown. 15 (M is one or more elements from Al and Ga) When the peak positions of the X-ray powder diffraction patterns of a crystal are consistent in terms of the principal peaks, it is determined that the two crystals have the same crystal structure. That is, the crystal structure of a crystal with an unknown crystal structure is the same as that of Ba5La3MgAl3O. 15 Crystals with the same crystal structure.

[0114] At the same time, by Figure 6 The elemental distribution mapping image of the near-infrared phosphor B3 prepared in Example 3 further confirms the reliability of the high-temperature solid-state method for synthesizing the near-infrared phosphor of the present invention.

[0115] The X-ray powder diffraction patterns of the near-infrared phosphors B6-B9 prepared in Examples 6-9 are consistent with those of the near-infrared phosphor B3 prepared in Example 3, and no obvious impurity peaks were observed.

[0116] Detection Example 3

[0117] The near-infrared phosphors B3-B10 prepared in Examples 3-10 were analyzed using fluorescence spectroscopy. The results for near-infrared phosphors B3, B4, B5-B7, and B10 prepared in Examples 3, 4, 5-7, and 10 are as follows: Figures 7-9as shown.

[0118] By Figure 7 The graph of the excitation spectrum and the emission spectrum of the near-infrared fluorescent powder B3 prepared in Example 3 shows that the emission peak of the near-infrared fluorescent powder B3 prepared in Example 3 under the excitation wavelength of 468 nm is located at 925 nm, and under the blue light excitation of 468 nm, the near-infrared fluorescent powder can exhibit the near-infrared light emission characteristics, and it can be seen that the near-infrared fluorescent powder can be excited by blue light to emit near-infrared light, so that the near-infrared fluorescent powder can convert blue light into near-infrared light.

[0119] By Figure 8 The graph of the excitation spectrum and the emission spectrum of the near-infrared fluorescent powder B4 prepared in Example 4 shows that the emission peak of the near-infrared fluorescent powder B4 prepared in Example 4 under the excitation wavelength of 480 nm is located at 940 nm, and under the blue light excitation of 480 nm, the near-infrared fluorescent powder can exhibit the near-infrared light emission characteristics, and it can be seen that the near-infrared fluorescent powder can be excited by blue light to emit near-infrared light, so that the near-infrared fluorescent powder can convert blue light into near-infrared light.

[0120] By Figure 9 The emission spectrum graph of the near-infrared fluorescent powder B3, B5-B7 and B10 prepared in Example 3, Example 5-7 and Example 10 under the excitation wavelength of 468 nm shows that the near-infrared fluorescent powder B5-B7 prepared in Example 5-7 of the present application exhibits the emission spectrum of near-infrared light emission under the excitation wavelength of 468 nm, that is, the blue light excitation exhibits the phenomenon of near-infrared light emission and the light emission intensity is enhanced compared with Example 3; the near-infrared fluorescent powder B10 prepared in Example 10 of the present application exhibits the emission spectrum of near-infrared light emission under the excitation wavelength of 468 nm, that is, the blue light excitation exhibits the phenomenon of near-infrared light emission and the light emission intensity is weakened compared with Example 3, so the experimental method of the present application is preferably the secondary calcination method as shown in Example 3.

[0121] The near-infrared fluorescent powder B8-B9 prepared in Example 8-9 of the present application exhibits the phenomenon of near-infrared light emission under the blue light excitation and the light emission intensity is enhanced compared with Example 3.

[0122] Detection Example 4

[0123] The fluorescence spectrometer and the heating table are used to analyze the light emission stability of the near-infrared fluorescent powder B5 prepared in Example 5, and the results are shown in Figure 10 as shown.

[0124] By Figure 10The graph shows the luminescence intensity of the near-infrared phosphor B5 prepared in Example 5 as a function of temperature under excitation wavelength of 468 nm. The luminescence intensity of the near-infrared phosphor B5 prepared in Example 5 of this invention gradually decreases with increasing temperature under excitation wavelength of 468 nm. When the temperature is 423 K, the luminescence intensity remains at 61% of that at 298 K, which is superior to the currently reported Cr... 3+ Activated broadband near-infrared phosphors can solve the problems of existing long-wave near-infrared (λ) phosphors. max Problems such as low quantum efficiency (>900nm) and severe thermal quenching.

[0125] Application Example 1

[0126] The application of the near-infrared phosphor B5 prepared in Example 5 in night vision yielded the following results: Figure 11 As shown.

[0127] Figure 11 Figure i shows a photo taken with a mobile phone when the incandescent light is on, in which the ornament is clearly visible; Figure ii shows a photo taken with a mobile phone when the incandescent light is off, in which the ornament is not visible; Figure iii shows a photo taken with a near-infrared camera under illumination by a near-infrared LED light made from the phosphor prepared in Example 5, in which the ornament is clearly visible. This demonstrates that the material can be used as a NIR light source and has certain application potential in night vision.

[0128] Application Example 2

[0129] The near-infrared phosphor B5 prepared in Example 5 was applied to biological tissue monitoring and object penetration, and the results are as follows: Figure 12 As shown.

[0130] Figure 12 As shown in a i A photograph of a hand taken with a mobile phone under incandescent light; the veins in the palm are not visible. ii A photograph of a hand taken with a near-infrared camera under the illumination of a near-infrared LED lamp made with the phosphor prepared in Example 5 is shown in the figure. The blood vessels in the palm are clearly visible. Figure bi is a photograph taken with a mobile phone under incandescent light, showing a colored cardboard and a staple (the staple is hidden behind the colored cardboard). The staple is not visible. Figure bii is a photograph taken with a near-infrared camera under the illumination of a near-infrared LED lamp made with the phosphor prepared in Example 5. The hidden staple is faintly visible in the image. This demonstrates the near-infrared phosphor of the present invention's ability to monitor and penetrate biological tissues, illustrating the application prospects of the near-infrared phosphor of the present invention in fields such as medicine and safety monitoring.

[0131] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0132] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0133] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A near-infrared fluorescent powder, characterized by, The near-infrared fluorescent powder has a chemical general formula: Ba5La3Mg 1-x MO 15 :Cr x ; wherein, M is Al or Ga; 0.001≤x≤0.07。 2. The near-infrared fluorescent powder according to claim 1, characterized by The excitation wavelength of the near-infrared fluorescent powder is 350-800 nm, and the emission peak is 700-1400 nm.

3. A method for producing a near-infrared fluorescent powder as claimed in claim 1 or 2, characterized by, The preparation method comprises the following steps: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, and sintering to obtain the near-infrared fluorescent powder; wherein, The M precursor is an Al precursor or a Ga precursor; The molar ratio of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is 5:3:1-x:3:x, wherein 0.001≤x≤0.07, the Ba precursor is calculated in terms of Ba atoms, the La precursor is calculated in terms of La atoms, the Mg precursor is calculated in terms of Mg atoms, the M precursor is calculated in terms of M atoms, and the Cr precursor is calculated in terms of Cr atoms.

4. The production method according to claim 3, characterized by, The purity of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is not less than 99.9%.

5. The preparation method according to claim 3, characterized in that, The Ba precursor is selected from one or more than two of carbonates of Ba, oxides of Ba, oxalates of Ba and nitrates of Ba; The La precursor is selected from one or more than two of carbonates of La, oxides of La, oxalates of La and nitrates of La; The Mg precursor is selected from one or more than two of carbonates of Mg, oxides of Mg, oxalates of Mg and nitrates of Mg; When the M precursor is an Al precursor, the Al precursor is selected from one or more than two of carbonates of Al, oxides of Al and nitrates of Al; When the M precursor is a Ga precursor, the Ga precursor is selected from oxides of Ga and / or nitrates of Ga; The Cr precursor is selected from one or more than two of carbonates of Cr, oxides of Cr and nitrates of Cr.

6. The preparation method according to claim 3, characterized in that, The sintering conditions comprise: in a reducing atmosphere, the temperature is 1400-1600 ℃, the heating rate is 1-5 ℃ / min, and the time is 4-8 h; The reducing atmosphere is a mixed atmosphere of hydrogen and argon and / or a mixed atmosphere of hydrogen and nitrogen; The gas content ratio of the hydrogen and argon is 1:5-20; The gas content ratio of the hydrogen and nitrogen is 1:5-20.

7. A method for preparing the near-infrared fluorescent powder according to claim 1 or 2, characterized by, The preparation method comprises the following steps: mixing a Ba precursor, a La precursor, a Mg precursor, an M precursor and a Cr precursor, and sintering to obtain the near-infrared fluorescent powder; wherein, The M precursor is an Al precursor or a Ga precursor; The molar ratio of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is 5:3:1-x:3:x, wherein 0.001≤x≤0.07, the Ba precursor is calculated in terms of Ba atoms, the La precursor is calculated in terms of La atoms, the Mg precursor is calculated in terms of Mg atoms, the M precursor is calculated in terms of M atoms, and the Cr precursor is calculated in terms of Cr atoms.

8. The production method according to claim 7, characterized by, The Ba precursor is selected from one or more than two of carbonates of Ba, oxides of Ba, oxalates of Ba and nitrates of Ba; The La precursor is selected from one or more of carbonates, oxides, oxalates and nitrates of La; The Mg precursor is selected from one or more of carbonates, oxides, oxalates and nitrates of Mg; When the M precursor is an Al precursor, the Al precursor is selected from one or more of carbonates, oxides and nitrates of Al; When the M precursor is a Ga precursor, the Ga precursor is selected from oxides and / or nitrates of Ga; The Cr precursor is selected from one or more of carbonates, oxides and nitrates of Cr.

9. The preparation method according to claim 7, characterized in that, The purity of the Ba precursor, the La precursor, the Mg precursor, the M precursor and the Cr precursor is not less than 99.9%.

10. The preparation method according to claim 7, characterized in that, The first sintering condition includes: in air atmosphere, temperature is 600-1000℃, heating rate is 4-8℃ / min, and time is 8-12h; The second sintering condition includes: in reducing atmosphere, temperature is 1400-1600℃, heating rate is 1-5℃ / min, and time is 4-8h; The reducing atmosphere is a mixed atmosphere of hydrogen and argon and / or a mixed atmosphere of hydrogen and nitrogen; The gas content ratio of hydrogen and argon is 1:5-20; The gas content ratio of hydrogen and nitrogen is 1:5-20; The preparation method further comprises adding a fluxing agent during the first sintering; The amount of the fluxing agent is 0.5%-2% of the total mass of the precursors.

11. Use of the near-infrared fluorescent powder according to claim 1 or 2 in the preparation of night vision products, infrared light-emitting diodes and rapid analysis.

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