Near-infrared matrix luminescent fluorescent powder, preparation method and application thereof

Abstract

The application provides a near-infrared matrix luminescent fluorescent powder, a preparation method and application thereof. x Cr y Sb z O4, and the excitation spectrum of the near-infrared matrix luminescent fluorescent powder is in a blue light region of 400-500 nm, and can be excited by a 450 nm blue light LED chip. By changing the feeding ratio of raw materials MgO, Cr2O3 and Sb2O3, an ultralong wide spectrum emission covering a first imaging window (NIR-I, 750-950 nm) and a second imaging window (NIR-II, 1000-1800 nm) can be generated, so that the near-infrared matrix luminescent fluorescent powder has a lower tissue absorption and scattering coefficient, can realize a greater detection depth and a higher imaging signal-to-noise ratio, and can be used in the field of biological imaging. In addition, since the emission range overlaps with the vibration frequency of most organic groups, such as O-H, N-H and C-H bonds, the near-infrared matrix luminescent fluorescent powder can be used in the fields of food and pharmaceutical component detection.

Description

Technical Field

[0001] This invention relates to the field of near-infrared phosphors, specifically to a near-infrared matrix luminescent phosphor, its preparation method, and its application. Background Technology

[0002] Biological compounds and tissues (such as blood, fat, and skin) can specifically absorb and scatter any incident light to varying degrees. Therefore, optical imaging must operate within a specific electromagnetic spectrum region and require minimal light attenuation to improve imaging contrast and sensitivity, as well as reduce background noise. Compared to the conventional first imaging window (NIR-I, 750-950 nm), the second imaging window (NIR-II, 1000-1800 nm) exhibits lower tissue absorption and scattering coefficients, enabling greater detection depth and a higher imaging signal-to-noise ratio.

[0003] Currently, NIR-II fluorescent materials are attracting increasing attention from researchers. NIR-II fluorescent materials can be divided into two types: organic fluorescent materials and inorganic fluorescent materials. Organic fluorescent materials include anthocyanins, donor-acceptor-donor (DAD) conjugated structures, phthalocyanines, etc., while inorganic fluorescent materials include carbon nanotubes, rare earth nanoparticles, quantum dots, etc. In the research of inorganic fluorescent materials, patent application (CN 112500851 A) discloses a high-efficiency Cr... 3+ Doped broadband near-infrared phosphors and their preparation methods, Cr 3+ Ions exhibit luminescence properties induced by dd transitions and possess a very wide tunable wavelength range, making them ideal activators for near-infrared luminescent materials. They are typically produced using Cr or Cr combined with rare earth elements such as Nd, Yb, and Ce, and incorporated into a Mg matrix. 1-x-0.5y N x M y Effective luminescent centers are formed in O, and the emission spectrum width can be effectively adjusted by changing the components. However, this material requires Cr or Cr and rare earth ion doping, and rare earth ions are relatively expensive. Therefore, the research progress on inorganic NIR-II phosphors is still quite slow. Summary of the Invention

[0004] The purpose of this invention is to provide a near-infrared matrix luminescent phosphor, its preparation method and application. This phosphor is a matrix luminescent material that does not require any doping and can generate near-infrared emission on its own. Moreover, the near-infrared emission is an ultra-wideband emission of 700-1600nm, which breaks through the emission range of traditional chromium ions. The ultra-long wavelength and wide-spectrum emission enable it to be applied in fields such as biological imaging, food detection, and pharmaceutical component detection.

[0005] This invention is implemented as follows:

[0006] A near-infrared matrix-emitting phosphor with the general chemical formula Mg x Cr y Sb z O4; where 2≤x≤2.24, 0.15≤y≤0.5, 0.5≤z≤0.62, and x+y+z=3.

[0007] The phosphor provided by this invention can be excited by light in the wavelength range of 400-500nm and emit near-infrared light in the range of 700-1600nm.

[0008] The preparation method of the above-mentioned near-infrared matrix luminescent phosphor includes the following steps:

[0009] a. According to the general chemical formula Mg x Cr y Sb z The molar ratio of Mg, Cr, and Sb in O4 is determined by weighing MgO, Cr2O3, and Sb2O3 raw materials respectively; wherein 2≤x≤2.24, 0.15≤y≤0.5, 0.5≤z≤0.62, and x+y+z=3;

[0010] b. Grind and mix the weighed raw materials thoroughly and place them in a crucible;

[0011] c. Place the crucible in an electric furnace and keep it at 1200-1500℃ for 1-10 hours;

[0012] d. After cooling the sample to room temperature, remove it and grind it evenly to obtain the near-infrared matrix luminescent phosphor Mg. x Cr y Sb z O4.

[0013] Preferably, in steps b and d, the grinding time is 10-30 minutes.

[0014] Preferably, the heating rate in step c is 3℃ / min, and the cooling rate in step d is 5℃ / min.

[0015] Preferably, in step c, the sintering atmosphere is air.

[0016] The near-infrared matrix-emitting phosphor provided by this invention can produce an ultra-long, broad-spectrum emission covering both the first imaging window (NIR-I, 750-950 nm) and the second imaging window (NIR-II, 1000-1800 nm). This results in lower tissue absorption and scattering coefficients, enabling greater detection depth and a higher imaging signal-to-noise ratio, making it suitable for use in the field of bioimaging. Furthermore, because its emission range overlaps with the vibrational frequencies of most organic groups, such as OH, NH, and CH bonds, it can also be used for food and pharmaceutical component detection.

[0017] The present invention has the following beneficial effects:

[0018] (1) Currently, most inorganic fluorescent materials that can produce NIR-II luminescence are rare earth ion-doped phosphors, and most of them emit in a narrow band, which cannot meet the requirements of spectral detection; moreover, the doped rare earth ions are expensive. The NIR-II phosphor prepared by this invention does not require any doping, and the material itself can produce near-infrared luminescence, and the raw materials are cheap and can be mass-produced.

[0019] (2) This invention designs and prepares a phosphor Mg with NIR-II emission. x Cr y Sb z O4 is a matrix-based luminescent material that can produce ultra-wideband emission in the range of 700-1600 nm, with peak wavelengths at 1250 nm and 860 nm. This invention breaks through the luminescence range of traditional chromium ions.

[0020] (3) The present invention prepares near-infrared matrix luminescent phosphor by a simple high-temperature solid-state method. The phosphor can achieve NIR-II luminescence; and has a large Stokes shift, strong anti-interference ability, low light damage to biological samples, strong penetration and high sensitivity; its ultra-long emission range can be widely used in fields such as biological imaging, food detection and drug detection. Attached Figure Description

[0021] Figure 1 These are the XRD diffraction patterns of the phosphors in Examples 1-7 of this invention.

[0022] Figure 2 This is a graph showing the intensity variation of phosphor in Examples 1-7 of the present invention.

[0023] Figure 3 This is the excitation spectrum of the phosphor in Example 6 of the present invention.

[0024] Figure 4 These are the diffuse reflectance spectra of the phosphors in Examples 1, 2, and 6 of this invention. Detailed Implementation

[0025] The near-infrared matrix-emitting phosphor provided by this invention has the general chemical formula Mg. x Cr y Sb z O4; where 2≤x≤2.24, 0.15≤y≤0.5, 0.5≤z≤0.62, and x+y+z=3. This near-infrared matrix luminescent phosphor can achieve NIR-II broadband emission.

[0026] The preparation method of the near-infrared matrix luminescent phosphor of the present invention is described in detail below with specific embodiments.

[0027] Example 1: Mg2Cr 0.5 Sb 0.5 Preparation of O4 phosphor.

[0028] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4:1:1. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0029] Example 2: Mg 2.1 Cr 0.35 Sb 0.55 Preparation of O4 phosphor.

[0030] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.2:0.7:1.1. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0031] Example 3: Mg 2.13 Cr 0.3 Sb 0.57 Preparation of O4 phosphor.

[0032] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.26:0.6:1.14. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0033] Example 4: Mg 2.16 Cr 0.25 Sb 0.59 Preparation of O4 phosphor.

[0034] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.32:0.5:1.18. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0035] Example 5: Mg 2.2 Cr 0.2 Sb 0.6 Preparation of O4 phosphor.

[0036] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.4:0.4:1.2. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. Then, it was cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0037] Example 6: Mg 2.23 Cr 0.15 Sb 0.62 Preparation of O4 phosphor.

[0038] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.46:0.3:1.24. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0039] Example 7: Mg 2.26 Cr 0.1 Sb 0.64 Preparation of O4 phosphor.

[0040] Using MgO, Cr2O3, and Sb2O3 as raw materials, MgO, Cr2O3, and Sb2O3 were weighed according to a molar ratio of Mg:Cr:Sb = 4.52:0.2:1.28. The mixture of MgO, Cr2O3, and Sb2O3 was thoroughly ground and mixed, then placed in a high-purity corundum crucible. The crucible was then transferred to a high-temperature electric furnace, and the temperature inside the crucible was raised to 1500℃ at a rate of 3℃ / min and maintained for 6 hours. The temperature was then cooled to room temperature at a rate of 5℃ / min, and the resulting product was thoroughly ground to obtain the desired phosphor material.

[0041] The relative emission spectral intensity of the phosphors prepared in Examples 1-7 was tested (excitation light at 450 nm), and the specific test results are shown in Table 1.

[0042] Table 1. Luminous intensity of phosphors in Examples 1-7

[0043] Example Oxide phosphor Mg:Cr:Sb feed ratio relative strength 1 <![CDATA[Mg2Cr 0.5 Sb 0.5 O4]]> 4:1:1 0 2 <![CDATA[Mg 2.1 Cr 0.35 Sb 0.55 O4]]> 4.2:0.7:1.1 330 3 <![CDATA[Mg 2.13 Cr 0.3 Sb 0.57 O4]]> 4.26:0.6:1.14 620 4 <![CDATA[Mg 2.16 Cr 0.25 Sb 0.59 O4]]> 4.32:0.5:1.18 990 5 <![CDATA[Mg 2.2 Cr 0.2 Sb 0.6 O4]]> 4.4:0.4:1.2 7610 6 <![CDATA[Mg 2.23 Cr 0.15 Sb 0.62 O4]]> 4.46:0.3:1.24 16610 7 <![CDATA[Mg 2.26 Cr 0.1 Sb 0.64 O4]]> 4.52:0.2:1.28 13409

[0044] As shown in Table 1, the phosphor Mg2Cr in Example 1 0.5 Sb 0.5 O4 does not emit light and has no luminescence intensity. The luminescence intensity of the phosphor in Examples 2-6 gradually increases, and the luminescence intensity of the phosphor in Example 6 is about 50 times that of the phosphor in Example 2.

[0045] XRD tests were performed on the phosphors in Examples 1-7, and the results are as follows: Figure 1 As shown. (Through) Figure 1 A comparison of the XRD diffraction patterns of the phosphors in each example with the standard card shows that the XRD diffraction patterns of Examples 1-6 are consistent with the standard card, indicating that the phosphors prepared in Examples 1-6 are free of impurities. Impurity phases appeared in the phosphor in Example 7.

[0046] The phosphors in Examples 1-7 were excited using 450nm light, and the resulting emission spectra are as follows: Figure 2 As shown. By Figure 2 It can be seen that the intensity of phosphor emission varies with different feed ratios. Overall, as the proportion of Cr decreases, the luminescence of the sample gradually increases. NIR-I emission occurs when the Mg:Cr:Sb feed ratio is 4.4:0.4:1.2, and the luminescence is strongest when the Mg:Cr:Sb feed ratio is 4.46:0.3:1.24.

[0047] Figure 3 The excitation spectrum of the phosphor prepared in Example 6 of this invention shows that the positions of the excitation peaks of the sample are basically the same under monitoring at 860 nm and 1250 nm, and both can be matched with 450 nm blue LED chips, indicating that it has commercial prospects.

[0048] Figure 4 The diffuse reflectance spectra of the phosphors prepared in Examples 1, 2, and 6 of this invention show that the samples exhibit strong absorption in the ranges of 400-500 nm and 600-700 nm, which is basically consistent with the excitation spectra.

[0049] The above embodiments are all mature implementations of the present invention, but the present invention is not limited to the above specific limitations. Any other materials that are replaced or modified based on the characteristics and methods of the present material are considered infringements.

Claims

1. A near-infrared matrix-based luminescent phosphor, characterized in that, Its general chemical formula is Mg x Cr y Sb z O4; Wherein, 2<x≤2.24, 0.15≤y<0.5, 0.5<z≤0.62, and x+y+z=3; the phosphor can be excited by light in the wavelength range of 400-500 nm and emits near-infrared light in the range of 700-1600 nm.

2. A method for preparing the near-infrared matrix luminescent phosphor according to claim 1, characterized in that, Includes the following steps: a. According to the general chemical formula Mg x Cr y Sb z The molar ratio of Mg, Cr and Sb in O4 is determined by weighing MgO, Cr2O3 and Sb2O3 raw materials respectively; wherein, 2<x≤2.24, 0.15≤y<0.5, 0.5<z≤0.62, and x+y+z=3; b. Grind and mix the weighed raw materials thoroughly and place them in a crucible; c. Place the crucible in an electric furnace and keep it at 1200~1500℃ for 1~10 h; d. After cooling the sample to room temperature, remove it and grind it evenly to obtain the near-infrared matrix luminescent phosphor Mg. x Cr y Sb z O4.

3. The method for preparing near-infrared matrix luminescent phosphor according to claim 2, characterized in that, In steps b and d, the grinding time is 10-30 minutes.

4. The method for preparing near-infrared matrix luminescent phosphor according to claim 2, characterized in that, The heating rate in step c is 3℃ / min, and the cooling rate in step d is 5℃ / min.

5. The method for preparing near-infrared matrix luminescent phosphor according to claim 2, characterized in that, In step c, the sintering atmosphere is air.

6. The applications of the near-infrared matrix luminescent phosphor according to claim 1 and the near-infrared matrix luminescent phosphor prepared according to any one of claims 2 to 5 in bioimaging, food detection, and drug component detection.

Images