Broadband long-wave-emission heat-quenching-resistant near-infrared fluorescent powder material and preparation method thereof

Abstract

The invention discloses a broadband long-wave-emission heat-quenching-resistant near-infrared fluorescent powder material and a preparation method thereof. The chemical formula of the fluorescent powder material is (0.5-0.25 y) Li2O. (2.5-0.5 x-0. 25y) R2O3: xCr < 3 + >, yNi < 2 + >, R is a compound of elements Ga and Al, x is more than or equal to 0.01 and less than or equal to 0.20, y is more than or equal to 0.005 and less than or equal to 0.16, and x is more than or equal to 0.01 and less than or equal to 0.20. The fluorescent powder is synthesized through a high-temperature solid-phase method, the prepared fluorescent powder material is stable in chemical property and excellent in luminescence property, can be excited by a blue light LED chip and emits broadband near-infrared light within the range of 1000-1600 nm, and the preparation method is simple, easy to operate, free of pollution and low in cost, can be used in the fields of construction of fluorescence conversion type LED devices with broadband near-infrared output and the like, and has great application prospects.

Description

Technical Field

[0001] The present invention relates to a phosphor material, in particular to a near-infrared phosphor material with broadband long-wave emission and thermal quenching resistance, and also relates to a preparation method of the above phosphor material. Background Art

[0002] Near-infrared spectroscopy (NIRS) is an important analytical method. It uses spectra in the wavelength range of 700 - 2500 nm for analysis and is widely used in fields such as biomedical imaging, food safety detection, agricultural quality analysis, and industrial process monitoring, with advantages such as fast speed, simplicity, and non-destructiveness. Pc-LED (phosphor-converted LED) is one of the main light sources of near-infrared spectroscopy. Near-infrared pc-LEDs are usually made of blue / ultraviolet LED chips paired with near-infrared phosphors. Near-infrared phosphors are the core materials for pc-LEDs to achieve efficient near-infrared emission, and the optimization of their performance has promoted the practical application of near-infrared spectroscopy.

[0003] Especially in recent years, spectral technologies in the near-infrared II region (1000 - 1700 nm) have shown unique advantages in various fields. In the biomedical field, NIR-II region (1000 - 1700 nm) imaging technology, with a tissue penetration depth of more than 5 cm and sub-millimeter resolution, has significantly improved the navigation accuracy of minimally invasive surgery; in the fields of materials science and industrial inspection, near-infrared spectroscopy, by analyzing the overtone absorption of C-H bonds in polymers at 1200 - 1400 nm, has achieved precise determination of the additive content in materials such as polyethylene (detection limit < 0.1 wt%); in the detection of semiconductor materials, lock-in thermography technology in the 1550 nm band can identify micro-defects < 10 μm in silicon wafers.

[0004] However, the emission of existing efficient near-infrared emission systems is mainly concentrated in the band less than 1000 nm, and there is still a lack of efficient long-wave emission systems; at the same time, food component detection, industrial or scientific spectral analysis systems require a continuous near-infrared light source with as wide a spectral band as possible. However, when the emission spectral band of existing near-infrared phosphors redshifts or broadens towards the long wave, it is often accompanied by a sharp decline in luminous efficiency and thermal quenching resistance, which greatly affects the application of near-infrared spectroscopy. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a near-infrared phosphor material with a longer wavelength, a wider spectral band, and better thermal quenching resistance. Another object of the present invention is to provide a preparation method of the above phosphor material.

[0006] Technical solution: The present invention discloses a near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching. The crystal structure of the near-infrared phosphor material is an inverse spinel structure, and its chemical formula is (0.5 - 0.25y)Li2O·(2.5 - 0.5x - 0.25y)R2O3:xCr 3+ ,yNi 2+ ; wherein, R is a composite of elements Ga and Al, and Ga and Al can be combined in any molar ratio, 0.01 ≤ x ≤ 0.20, 0.005 ≤ y ≤ 0.16.

[0007] The preparation method of the above near-infrared phosphor material includes the following steps:

[0008] (1) Take the oxygen-containing compounds or their corresponding salts of raw materials Mg, Cr, Ni, and R, add a reaction flux, seal and burn to obtain a pre-burned product;

[0009] (2) Take the above pre-burned product, grind it, seal and burn to obtain a burned product;

[0010] (3) Take the above burned product and perform post-treatment to obtain a near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching.

[0011] Among them, in step (1), the oxygen-containing compounds of raw materials Mg, Cr, Ni, and R are magnesium oxide, chromium sesquioxide, nickel oxide, gallium oxide, and aluminum oxide, and the corresponding salts are magnesium carbonate.

[0012] Among them, in step (1), the flux is one or more of alkali metal halides, inorganic oxides, alkali metal carbonates, and boric acid.

[0013] Among them, in step (1), the dosage of the flux is 0.05% - 3% of the total weight of the raw materials.

[0014] Among them, in step (1), the pre-burning conditions are: the heating rate is 3 - 5 °C / minute, the temperature is 750 - 800 °C, and the holding time is 1.5 - 2 h.

[0015] Among them, in step (2), the burning conditions are: the heating rate is 3 - 5 °C / minute, the holding temperature is 1100 - 1350 °C, and the burning time is 4 - 8 h.

[0016] Among them, in step (3), the post-treatment specifically is to grind the calcined product into powder, sieve it, wash it 1 - 3 times, centrifuge it, and dry the precipitate; the drying temperature of the precipitate is 80 °C - 120 °C.

[0017] Principle of the invention: The broadband long-wave emission anti-thermal quenching near-infrared phosphor material of the present invention uses a spinel structure AB2O4 as the matrix, with Li occupying the octahedral position (B position), where the R (a composite of Ga and Al) element simultaneously occupies the tetrahedral position (A position) and the remaining octahedral positions (B positions), forming an arrangement of (R3+)[Li+R3+4]O8; Cr 3+ and Ni 2+ are luminescent ions, and by utilizing the energy transfer from Cr 3+ to Ni 2+ , broadband long-wave emission is achieved under blue light excitation; the Ni 2+ ion itself has broadband long-wave emission. After adding the Cr 3+ ion, it has extremely high luminous efficiency and good thermal stability in the inverse spinel structure, enabling the phosphor material to have a stable and well-crystallized effect while having a wide emission and excitation coverage range. Based on the chemical formula AB2O4, the present invention combines Ga and Al to enhance rigidity and form a spinel structure. And to avoid uneven distribution of elements inside the crystal caused by the introduction of multiple atoms, the synthesis process is adjusted to make the sample a single crystal with better crystallinity, increasing the luminous efficiency and thermal stability of the luminescent material, enabling the phosphor material to have a stable and well-crystallized effect while having a wide emission and excitation coverage range.

[0018] Advantageous effects: Compared with the prior art, the present invention has the following remarkable advantages: (1) The broadband long-wave emission anti-thermal quenching near-infrared phosphor material of the present invention has a wide emission coverage range, can emit near-infrared light in the range of 1000 - 1600 nm, and has high luminous efficiency, strong luminous thermal stability, and small luminous thermal quenching. The excitation range of the phosphor material is wide and can be effectively excited by visible light in the range of 380 - 700 nm; (2) The performance of this phosphor material is stable, and the luminous intensity remains basically unchanged after processes such as heating and soaking in water; (3) The preparation method of the present invention is simple, easy to operate, pollution-free, and low-cost. Description of the drawings

[0019] Figure 1 It is the X-ray diffraction spectrum of the near-infrared phosphor materials of Examples 1 - 3 and Comparative Examples 1 - 2 of the present invention and the comparison with the standard PDFs 38 - 1371 of LiGa5O8 and 38 - 1425 of LiAl5O8;

[0020] Figure 2 It is the excitation and emission spectra of the near-infrared phosphor material of Example 1 of the present invention;

[0021] Figure 3 It is the internal quantum efficiency spectrum of the near-infrared phosphor material of Example 1 of the present invention;

[0022] Figure 4Emitted light of the near-infrared phosphor material of Example 1 of the present invention at different temperatures;

[0023] Figure 5 Excitation and emission spectra of the near-infrared phosphor material of Example 2 of the present invention;

[0024] Figure 6 Internal quantum efficiency spectrum of the near-infrared phosphor material of Example 2 of the present invention;

[0025] Figure 7 Excitation and emission spectra of the near-infrared phosphor material of Example 3 of the present invention;

[0026] Figure 8 Excitation and emission spectra of the near-infrared phosphor material of Example 4 of the present invention;

[0027] Figure 9 Excitation and emission spectra of the near-infrared phosphor material of Example 5 of the present invention;

[0028] Figure 10 Excitation and emission spectra of the near-infrared phosphor material of Example 6 of the present invention;

[0029] Figure 11 Excitation and emission spectra of the near-infrared phosphor material of Example 7 of the present invention;

[0030] Figure 12 Excitation and emission spectra of the near-infrared phosphor material of Example 8 of the present invention;

[0031] Figure 13 Excitation and emission spectra of the phosphor material of Comparative Example 1 of the present invention;

[0032] Figure 14 Internal quantum efficiency spectrum of the phosphor material of Comparative Example 1 of the present invention;

[0033] Figure 15 Excitation and emission spectra of the phosphor material of Comparative Example 2 of the present invention;

[0034] Figure 16 Internal quantum efficiency spectrum of the phosphor material of Comparative Example 2 of the present invention;

[0035] Figure 17 Emitted light of the phosphor material of Comparative Example 2 of the present invention at different temperatures. Detailed implementation manners

[0036] The technical solution of the present invention will be further described below in conjunction with embodiments. The test materials used in the embodiments can be obtained through conventional channels.

[0037] Example 1

[0038] The near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching of the present invention has a chemical formula of 0.49Li2O·1.944Ga2O3·0.486Al2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0039] (1) Weigh 1.225 mmol of Li2CO3, 4.86 mmol of Ga2O3, 1.215 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.1 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 800 °C for 2 h to obtain a pre-sintered product;

[0040] (2) Place the pre-sintered product and 2% by weight of the raw material HBO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1250 °C for 4 h to obtain a calcined product;

[0041] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.49Li2O·1.944Ga2O3·0.486Al2O3:0.12Cr 3+ ,0.04Ni 2+ near-infrared phosphor of the present invention.

[0042] The X-ray diffraction spectrum of this example is as shown in the appendix Figure 1 . The diffraction peak pattern of this example coincides with that of the PDF card of the standard inverse spinel LiGa5O8, indicating that the material of this example has an inverse spinel structure. The peak position of this example moves towards a higher angle relative to the peak position of the standard example 1, which is due to the lattice contraction caused by the introduction of Al 3+ to replace the matrix Ga 3+ .

[0043] The excitation spectrum and emission spectrum are as shown in the appendix Figure 2 . Under the excitation of blue light at 420 nm, the phosphor of this example mainly shows a broad peak with a peak value at 1200 nm. This peak position comes from the 2+ T2→ 3 A2 transition of Ni 3 . Therefore, it can be seen that this example can also achieve broadband near-infrared emission in the range of 1000 - 1600 nm under blue light excitation; at the emission monitoring wavelength of 1200 nm, the excitation spectrum of this example consists of two excitation bands located at 410 nm and 600 nm respectively, mainly originating from the 3+ A2→ 4 T1, 4 A2→ 4 T2 energy level transitions of Cr 4 . The internal quantum efficiency spectrum of this example is as shown in the appendixFigure 3 As shown, due to the wavelength limitation of the detector, the efficiency of the phosphor under blue light excitation cannot be directly measured. Therefore, the peak internal quantum efficiency of the phosphor is 67.32% when excited at 610 nm. The emission spectra at different temperatures are as attached Figure 4 As shown, its emission intensity decreases to 63.52% of the room temperature intensity at 150 °C. Compared with Comparative Example 2, the thermal stability and internal quantum efficiency of the sample are improved because after the combination of Al and Ga, the symmetry of the matrix is changed, distortion appears inside the crystal, defects are generated, and when the temperature rises, the defects absorb thermal energy and convert it into light energy, ensuring the luminescence intensity of the sample at high temperatures.

[0044] Example 2

[0045] The broadband long-wavelength emission and thermally quenching-resistant near-infrared phosphor material of the present invention has a chemical formula of 0.49Li2O·1.215Ga2O3·1.215Al2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0046] (1) Weigh 1.225 mmol of Li2CO3, 3.0375 mmol of Ga2O3, 3.0375 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.1 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 800 °C for 2 h to obtain a pre-sintered product;

[0047] (2) Place the pre-sintered product and 2% by weight of the raw material HBO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1250 °C for 4 h to obtain a calcined product;

[0048] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.49Li2O·1.215Ga2O3·1.215Al2O3:0.12Cr 3+ ,0.04Ni 2+ near-infrared phosphor of the present invention.

[0049] The X-ray diffraction spectrum of this example is as attached Figure 1 As shown, this example contains the diffraction peak shapes of the PDF cards of standard inverse spinels LiGa5O8 and LiAl5O8, indicating that the material of this example is an inverse spinel structure.

[0050] The excitation spectrum and emission spectrum of this example are as attached Figure 5As shown, under the excitation of blue light at 420 nm, the phosphor of this example mainly exhibits a broad peak with a peak value at 1170 nm. At the emission monitoring wavelength of 1170 nm, the excitation spectrum of this example consists of two excitation bands located at 400 nm and 580 nm respectively. The internal quantum efficiency spectrum of this example is as attached Figure 6 As shown, due to the wavelength limitation of the detector, the efficiency of this phosphor under blue light excitation cannot be directly measured. Therefore, the internal quantum efficiency of the peak of this phosphor is measured to be 67.32% using 610 nm excitation. Compared with Comparative Example 1, the internal quantum efficiency of the sample has increased because after the combination of Al and Ga, the symmetry of the matrix is changed, distortion appears inside the crystal, non-radiative transitions of the phosphor are reduced, and the quantum efficiency is improved.

[0051] Example 3

[0052] The near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching of the present invention has a chemical formula of 0.49Li2O·0.486Ga2O3·1.944Al2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0053] (1) Weigh 1.225 mmol of Li2CO3, 1.215 mmol of Ga2O3, 4.86 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.1 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 800 °C for 2 h to obtain a pre-sintered product;

[0054] (2) Place the pre-sintered product and 2% by weight of the raw material HBO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1250 °C for 4 h to obtain a calcined product;

[0055] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.49Li2O·0.486Ga2O3·1.944Al2O3:0.12Cr 3+ ,0.04Ni 2+ near-infrared phosphor of the present invention.

[0056] The X-ray diffraction spectrum of this example is as attached Figure 1 As shown, the diffraction peak pattern of this example coincides with the PDF card of the standard inverse spinel LiGa5O8, indicating that the material of this example is an inverse spinel structure. The peak position of this example shifts to a lower angle relative to the peak position of Comparative Example 2, which is due to the lattice expansion caused by the introduction of Ga 3+ to replace the matrix Al 3+ resulting in lattice expansion.

[0057] The excitation spectrum and emission spectrum of this example are as shown in the appendix Figure 7 As shown, under the excitation of blue light at 420 nm, the phosphor of this example mainly exhibits a broad peak with a peak value at 1150 nm. Under the emission monitoring wavelength of 1150 nm, the excitation spectrum of this example consists of two excitation bands located at 400 nm and 560 nm respectively.

[0058] Example 4

[0059] The near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching of the present invention has a chemical formula of 0.47Li2O·1.928Ga2O3·0.482Al2O3:0.12Cr 3+ , 0.12Ni 2+ , and its preparation steps are as follows:

[0060] (1) Weigh 1.175 mmol of Li2CO3, 4.82 mmol of Ga2O3, 1.205 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.3 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 750 °C for 2 h to obtain a pre-sintered product;

[0061] (2) Place the pre-sintered product and 2% by weight of the raw material SiO2 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1100 °C for 4 h to obtain a calcined product;

[0062] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.47Li2O·1.928Ga2O3·0.482Al2O3:0.12Cr 3+ , 0.12Ni 2+ near-infrared phosphor of the present invention.

[0063] The excitation spectrum and emission spectrum of this example are as shown in the appendix Figure 8 As shown, under the excitation of blue light at 420 nm, the phosphor of this example mainly exhibits a broad peak with a peak value at 1250 nm. Under the emission monitoring wavelength of 1250 nm, the excitation spectrum of this example consists of two excitation bands located at 400 nm and 590 nm respectively.

[0064] Example 5

[0065] The near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching of the present invention has a chemical formula of 0.48Li2O·1.936Ga2O3·0.484Al2O3:0.12Cr 3+ , 0.08Ni 2+ , and its preparation steps are as follows:

[0066] (1) Weigh 1.2 mmol of raw material Li2CO3, 4.84 mmol of Ga2O3, 1.21 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.2 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 800 °C for 1.5 h to obtain a pre-sintered product;

[0067] (2) Place the pre-sintered product and 2% by weight of the raw materials of NH4F as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1300 °C for 6 h to obtain a calcined product;

[0068] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.48Li2O·1.936Ga2O3·0.484Al2O3:0.12Cr 3+ ,0.08Ni 2+ near-infrared phosphor of the present invention.

[0069] The excitation spectrum and emission spectrum of this example are as shown in the appendix Figure 9 shown. The excitation spectrum of this example is similar to that of Example 3, but compared with Example 3, the emission peak intensity at 1250 nm is weaker, and the intensity reduction is caused by the concentration quenching of Ni 2+ ions.

[0070] Example 6

[0071] The near-infrared phosphor material with broadband long-wave emission and thermal quenching resistance of the present invention has a chemical formula of 0.498Li2O·0.488Ga2O3·1.95Al2O3:0.12Cr 3+ ,0.01Ni 2+ , and its preparation steps are as follows:

[0072] (1) Weigh 1.24 mmol of raw material Li2CO3, 4.88 mmol of Ga2O3, 1.22 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.025 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 600 °C for 2 h to obtain a pre-sintered product;

[0073] (2) Place the pre-sintered product and 2% by weight of the raw materials of Na2CO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1300 °C for 4 h to obtain a calcined product;

[0074] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.498Li2O·0.488Ga2O3·1.95Al2O3:0.12Cr 3+, 0.01Ni 2+ Near-infrared phosphor

[0075] The excitation spectrum and emission spectrum of this example are as shown in the appendix Figure 10 The excitation spectrum of this example is similar to that of Example 1. However, compared with Example 1, the emission peak intensity at 1120 nm is weaker. The decrease in intensity is due to the decrease in the concentration of activator ions Ni 2+ ions concentration

[0076] Example 7

[0077] The near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching of the present invention has a chemical formula of 0.498Li2O·0.492Ga2O3·1.966Al2O3:0.08Cr 3+ , 0.01Ni 2+ , and its preparation steps are as follows:

[0078] (1) Weigh 1.24 mmol of Li2CO3, 4.92 mmol of Ga2O3, 1.23 mmol of Al2O3, 0.1 mmol of Cr2O3, and 0.025 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 600 °C for 2 h to obtain a pre-sintered product;

[0079] (2) Place the pre-sintered product and 2% by weight of the raw material HBO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1200 °C for 8 h to obtain a calcined product;

[0080] (3) After fully grinding the calcined product into powder and passing it through a 200-mesh sieve, wash it 3 times with deionized water and dry it at 80 °C to obtain the 0.498Li2O·0.492Ga2O3·1.966Al2O3:0.08Cr 3+ , 0.01Ni 2+ near-infrared phosphor of the present invention

[0081] The excitation spectrum and emission spectrum of this example are as shown in the appendix Figure 11 The excitation spectrum of this example is similar to that of Example 6. However, compared with Example 6, the emission peak intensity at 1120 nm is weaker. The concentration of Cr 3+ ions determines the absorption of blue light by the phosphor sample. Therefore, decreasing the concentration of Cr 3+ ions will weaken the emission light intensity

[0082] Example 8

[0083] The broadband long-wave emission near-infrared phosphor material resistant to thermal quenching of the present invention has a chemical formula of 0.49Li2O·1.215Ga2O3·1.215Al2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0084] (1) weighing raw materials Li2CO3 1.225 mmol, Ga2O3 3.0375 mmol, Al2O3 3.0375 mmol, Cr2O3 0.15 mmol, and NiO 0.1 mmol; mixing the weighed raw materials thoroughly, and sintering them at 800°C in air for 2 h to obtain a pre-calcined product;

[0085] (2) the pre-calcined product and 2% of the raw material weight of LiF as a flux were placed in a mortar and ground and mixed thoroughly, and then sintered at 1250° C. for 8 h in air to obtain a calcined product;

[0086] (3) The calcined product was fully ground into powder and passed through a 200-mesh sieve, then washed three times with deionized water and dried at 80° C. to obtain the 0.49Li2O·1.215Ga2O3·1.215Al2O3:0.12Cr 3+ ,0.04Ni 2+ Near-infrared phosphor.

[0087] The excitation spectrum and emission spectrum of this embodiment are shown in the attached Figure 12 As shown, the excitation spectrum of this embodiment is similar to that of embodiment 2, but compared with embodiment 2, the emission peak intensity at 1170 nm is weaker, and the effect of LiF as a flux is not as good as HBO3.

[0088] Comparative Example 1

[0089] A phosphor material, compared with the embodiment, a sample without Al element, the chemical expression is 0.49Li2O·2.43Ga2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0090] (1) weighing 1.225 mmol of Li2CO3, 6.075 mmol of Ga2O3, 0.15 mmol of Cr2O3, and 0.1 mmol of NiO as raw materials; mixing the weighed raw materials thoroughly, and sintering them at 800°C in air for 2 h to obtain a pre-sintered product;

[0091] (2) the pre-calcined product and HBO3 (2% by weight of the raw material) as a flux were placed in a mortar and ground thoroughly, and then sintered in air at 1250° C. for 4 h to obtain a calcined product;

[0092] (3) After the calcined product is sufficiently ground into powder and passed through a 200-mesh sieve, it is washed 3 times with deionized water and dried at 80 °C to obtain 0.49Li2O·2.43Ga2O3:0.12Cr 3+ ,0.04Ni 2+ phosphor material.

[0093] The X-ray diffraction spectrum of this comparative example is as shown in the appendix Figure 1 . The diffraction peak pattern of this comparative example coincides with that of the PDF card of the standard spinel LiGa5O8, indicating that the material of the comparative example is single-phase LiGa5O8.

[0094] The excitation spectrum and emission spectrum of this comparative example are as shown in the appendix Figure 13 . Under the excitation of blue light at 420 nm, this comparative example phosphor mainly exhibits a broad peak with a peak value at 1220 nm; under the emission monitoring wavelength of 1220 nm, the excitation spectrum of this comparative example consists of two excitation bands located at 420 nm and 610 nm respectively, mainly originating from the 3+ A2→ 4 T1, 4 A2→ 4 T2 energy level transitions; the internal quantum efficiency spectrum of this comparative example is as shown in the appendix 4 . Using 610 nm excitation to test the internal quantum efficiency of the phosphor peak is 62.15%. Figure 14

[0095] Comparative Example 2

[0096] A phosphor material. Compared with the example, the sample without compounding Ga element has a chemical formula of 0.49Li2O·2.43Al2O3:0.12Cr 3+ ,0.04Ni 2+ , and its preparation steps are as follows:

[0097] (1) Weigh 1.225 mmol of Li2CO3, 6.075 mmol of Al2O3, 0.15 mmol of Cr2O3, and 0.1 mmol of NiO; after fully mixing the weighed raw materials, sinter them in air at 800 °C for 2 h to obtain a pre-calcined product;

[0098] (2) Place the pre-calcined product and 2% by weight of the raw material HBO3 as a flux in a mortar, fully grind and mix them, and then sinter them in air at 1250 °C for 4 h to obtain a calcined product;

[0099] (3) After the obtained calcined product is sufficiently ground into powder and passed through a 200-mesh sieve, it is washed 3 times with deionized water and dried at 80 °C to obtain 0.49Li2O·2.43Al2O3:0.12Cr 3+ ,0.04Ni2+ Phosphor material.

[0100] The excitation spectrum and emission spectrum of this comparative example are as shown in the appendix Figure 15 As shown, under the excitation of blue light at 420 nm, the phosphor of this comparative example mainly exhibits a broad peak with a peak at 1120 nm. Under the emission monitoring wavelength of 1120 nm, the excitation spectrum of this comparative example consists of two excitation bands located at 400 nm and 570 nm respectively. The internal quantum efficiency spectrum of this comparative example is as shown in the appendix Figure 16 As shown, when using 610 nm excitation to test the phosphor, the internal quantum efficiency of the peak is 60.19%. The emission spectra at different temperatures are as shown in the appendix Figure 17 As shown, its emission intensity decreases to 30.17% of the room temperature intensity at 150 °C.

[0101] Therefore, the broadband long-wavelength emission anti-thermal quenching near-infrared phosphor material of the present invention has a wide emission coverage range, a wide excitation range, high luminous efficiency, strong luminous thermal stability, small luminous thermal quenching, and stable performance. After processes such as heating and water immersion, the luminous intensity remains basically unchanged; it can be used to construct a fluorescence conversion type LED device with broadband near-infrared output, and is extremely suitable for fields such as optical communication and solar cells, and has broad application value.

Claims

1. A near-infrared phosphor material for broadband long-wave emission with anti-thermal quenching, characterized in that, The crystal structure of the near-infrared phosphor material is an inverse spinel structure, and its chemical formula is (0.5 - 0.25y)Li2O·(2.5 - 0.5x - 0.25y)R2O3:xCr 3+ ,yNi 2+ ; wherein, R is a composite of elements Ga and Al, 0.01 ≤ x ≤ 0.20, 0.005 ≤ y ≤ 0.

16.

2. A method for preparing the near-infrared phosphor material according to claim 1, characterized in that, It includes the following steps: (1) Take the oxygen-containing compounds or their corresponding salts of raw materials Mg, Cr, Ni and R, add a reaction flux, seal and calcine to obtain a pre-calcined product; (2) Take the above pre-calcined product, grind it, seal and calcine to obtain a calcined product; (3) Take the above calcined product, perform post-treatment, and then obtain a near-infrared phosphor material with broadband long-wave emission and anti-thermal quenching.

3. The preparation method according to claim 2, characterized in that In step (1), the flux is one or more of alkali metal halides, inorganic oxides, alkali metal carbonates, and boric acid.

4. The preparation method according to claim 2, characterized in that, In step (1), the dosage of the flux is 0.05% - 3% of the total weight of the raw materials.

5. The preparation method according to claim 2, characterized in that, In step (1), the pre-calcination conditions are: the heating rate is 3 - 5 °C / minute, the temperature is 750 - 800 °C, and the holding time is 1.5 - 2 h.

6. The preparation method according to claim 2, characterized in that, In step (2), the calcination conditions are: the heating rate is 3 - 5 °C / minute, the holding temperature is 1100 - 1350 °C, and the calcination time is 4 - 8 h.

7. The preparation method according to claim 2, characterized in that, In step (3), the post-treatment specifically is to grind the calcined product into powder, sieve it, wash it 1 - 3 times, and dry the precipitate after centrifugation.

8. The preparation method according to claim 7, wherein In step (3), the drying temperature of the precipitate is 80 °C - 120 °C.

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