Near-infrared fluorescent powder and preparation method thereof

Abstract

The invention provides near-infrared fluorescent powder and a preparation method thereof. The general chemical formula of the near-infrared fluorescent powder is CaZrTaGa (1-x) CrxO7, wherein x is more than 0 and less than or equal to 0.05. The preparation method of the near-infrared fluorescent powder specifically comprises the following steps: (a) weighing oxides or carbonates containing Ca, Zr, Ta, Ga and Cr elements according to the molar ratio of the elements in the chemical general formula of the fluorescent powder, adding boric acid into the weighed raw materials, mixing and grinding to obtain a mixture; (b) heating the mixture to 900 DEG C, roasting for 6 hours, continuously heating to 1450 DEG C, roasting for 6 hours, and cooling to room temperature to obtain a sintered body; and (c) fully grinding the obtained sintered body to obtain the near-infrared fluorescent powder. The novel near-infrared fluorescent material is formed by doping Cr < 3 + > ions, and the novel near-infrared fluorescent material is simple in preparation process, easy to operate, low in cost and suitable for industrial large-scale production, popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and more particularly to a near-infrared phosphor and a preparation method thereof. Background Art

[0002] The near-infrared light region is a non-visible light region that was discovered relatively early by people. Due to the low early technical level, the influence of frequency doubling and sum frequency caused spectral overlap and complex analysis, resulting in certain limitations in the research and application of near-infrared light. It wasn't until the 1960s that the emergence of commercial instruments and the extensive work done by Norris et al. proposed the theory that the content of substances has a linear relationship with the absorption peaks at multiple different wavelength points in the near-infrared region, and the NIR diffuse reflection technology was used to measure components such as moisture, protein, and fat in agricultural products, which enabled the wide application of near-infrared spectroscopy technology in the analysis of agricultural and sideline products. In the mid- to late 1960s, with the emergence of various new analysis technologies and the weaknesses of low sensitivity and poor anti-interference ability exposed by the classical near-infrared spectroscopy analysis technology, people became less interested in the application of this technology in analysis and testing. After that, near-infrared spectroscopy entered a period of silence.

[0003] The successful application of multivariate calibration technology, an important part of the Chemometrics discipline that emerged in the 1970s, in spectral analysis promoted the popularization of near-infrared spectroscopy technology. By the late 1980s, with the rapid development of computer technology, it drove the digitization of analytical instruments and the development of chemometrics. The good results achieved by chemometric methods in solving spectral information extraction and background interference, combined with the unique characteristics of near-infrared spectroscopy in sample measurement technology, made people re-recognize the value of near-infrared spectroscopy, and the application research of near-infrared spectroscopy in various fields was successively carried out.

[0004] With the further development of near-infrared technology, near-infrared has been extended to many medical fields, such as pharmacology, molecular cell biology and diagnostics. Hospitals in the United States are trying to use a new instrument to help nurses find blood vessels on patients' arms. The principle is to detect the location of blood vessels with the help of near-infrared rays that are harmless to the human body, and project the distribution image of blood vessels onto the arm in real time, so that medical staff know where to insert the needle, which may save them from the pain of "wrongful needles". Near-infrared fluorescent markers emit light in the near-infrared region, where biological molecules do not emit light and there is no spectral overlap interference. Near-infrared fluorescent markers can be excited by visible light of shorter wavelengths, thereby avoiding the dispersion of excitation light and obtaining higher sensitivity. In addition, near-infrared light has a large penetration depth in living biological tissues, can generate light signals in deep tissues, and has almost no effect on the tissues themselves, so it is conducive to obtaining more biological information and plays a positive role in further promoting the development of medical imaging, tumor treatment and other technologies. In addition, near-infrared light can also be used in biometrics, such as fingerprint recognition, iris recognition, and face recognition. Near-infrared light can also be used in LEDs. The new broadband infrared LED launched by OSRAM Opto Semiconductors applies phosphor technology to infrared emitters for the first time, resulting in the successful creation of an LED that can emit broadband infrared light in the wavelength range of 600nm to 1100nm, creating infrared spectroscopy technology suitable for the consumer market and used in the food industry, agriculture and other industries to measure the moisture, fat, carbohydrates, sugar or protein content in food. Therefore, the research and development of near-infrared phosphors has become a topic of active research by R&D personnel in the current industry to provide more options for the needs of the near-infrared material market. SUMMARY OF THE INVENTION

[0005] The purpose of the present invention is to provide a near-infrared phosphor and a preparation method thereof, so as to provide more choices for the market demand for near-infrared materials.

[0006] The present invention is achieved by:

[0007] A near-infrared phosphor, the general chemical formula of which is: CaZrTaGa 1-x Cr x O 7 , where 0<x≤0.05.

[0008] Preferably, in the chemical formula, 0.005≤x≤0.05, the luminescence intensity of the near-infrared phosphor within the preferred range is relatively strong; more preferably, in the chemical formula, 0.005≤x≤0.02, the luminescence intensity of the near-infrared phosphor within the preferred range is relatively stronger; most preferably, when x=0.01 in the chemical formula, the luminescence intensity of the phosphor is the strongest.

[0009] The present invention also provides a method for preparing near-infrared phosphor, comprising the following steps:

[0010] (a) Weigh the oxides or carbonates containing the elements Ca, Zr, Ta, Ga, and Cr according to the molar ratios of the respective elements in the chemical general formula of the phosphor CaZrTaGa 1-x Cr x O 7 and 0.04 g of boric acid, mix and grind them to obtain a mixture, where 0 < x ≤ 0.05 in the chemical general formula.

[0011] (b) Heat the mixture to 900 °C and calcine for 6 h, then continue to heat it to 1450 °C and calcine for 6 h. After cooling to room temperature, a sintered body is obtained.

[0012] (c) Grind the obtained sintered body sufficiently to obtain the near-infrared phosphor CaZrTaGa 1-x Cr x O 7 .

[0013] The grinding time in step (a) is 15 - 30 min.

[0014] The heating rate in step (b) is 5 - 10 °C / min.

[0015] In the preparation method of the near-infrared phosphor provided by the present invention, in step (a), the weighed oxides or carbonates containing the elements Ca, Zr, Ta, Ga, and Cr are preferably CaCO 3 (99.9%), ZrO 2 (99%), Ta 2 O 5 (99%), Ga 2 O 3 (99.999%), Cr 2 O 3 (99%); the added boric acid satisfies: H 3 BO 3 (99.5%).

[0016] The near-infrared phosphor prepared by the present invention has a wide excitation wavelength range, high luminous intensity, good stability, high quantum efficiency, and high photoelectric conversion efficiency. The present invention adopts a new type of near-infrared fluorescent material doped and synthesized by Cr 3+ ions. The high-temperature solid-phase preparation method adopted has a simple preparation process, is easy to operate and control, has high safety, short preparation time, high production efficiency, and the production cost is greatly reduced compared with the prior art, and is suitable for industrial large-scale production and popularization and application. Description of the Drawings

[0017] Figure 1 is the X-ray diffraction pattern of the phosphors prepared in Examples 1 - 6 and the standard card.

[0018] Figure 2 are the excitation and emission spectra of the phosphor prepared in Example 2 (where the excitation wavelength λ ex = 461 nm and the emission wavelength λ em = 785 nm.)

[0019] Figure 3 are the emission spectra of the phosphors prepared in Examples 1 - 9. Detailed implementation manners

[0020] The following examples are used to further illustrate the present invention in detail, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field. However, the present invention is not limited in any form.

[0021] Example 1

[0022] (1) Weigh each raw material according to the following weights: respectively weigh 0.3850 g of calcium carbonate (CaCO 3 ), 0.4025 g of zirconium oxide (ZrO 2 ), 0.8498 g of tantalum oxide (Ta 2 O 5 ), 0.3587 g of gallium oxide (Ga 2 O 3 ), 0.0015 g of chromium(III) oxide (Cr 2 O 3 ) and 0.04 g of boric acid (H 3 BO 3 ). Mix them evenly and place them in an agate mortar to grind thoroughly for 30 min to obtain a mixture.

[0023] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter it at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter it again at this temperature for 6 h. Then cool it naturally to room temperature to obtain a sintered body.

[0024] (3) Grind the obtained sintered body thoroughly to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.995 Cr 0.005 O 7 .

[0025] The near-infrared phosphor prepared in this example has an emission center at 785 nm.

[0026] Example 2

[0027] (1) Weigh each raw material according to the following weights: respectively weigh calcium carbonate (CaCO 3) 0.3850 g of zirconium oxide (ZrO 2 ) 0.4025 g of tantalum oxide (Ta 2 O 5 ) 0.8498 g of gallium oxide (Ga 2 O 3 ) 0.3569 g of chromium(III) oxide (Cr 2 O 3 ) 0.0029 g and 0.04 g of boric acid (H 3 BO 3 ). Mix them evenly and place them in an agate mortar for thorough grinding for 30 min to obtain a mixture.

[0028] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter again at this temperature for 6 h, then cool it naturally to room temperature to obtain a sintered body.

[0029] (3) Thoroughly grind the obtained sintered body to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.99 Cr 0.01 O 7 .

[0030] Compared with Example 1, the phosphor prepared in this example has stronger light intensity.

[0031] Example 3

[0032] (1) Weigh the following raw materials by weight: Weigh 0.3850 g of calcium carbonate (CaCO 3 ), 0.4025 g of zirconium oxide (ZrO 2 ), 0.4025 g of tantalum oxide (Ta 2 O 5 ), 0.8498 g of gallium oxide (Ga 2 O 3 ), 0.3551 g of chromium(III) oxide (Cr 2 O 3 ), 0.0044 g and 0.04 g of boric acid (H 3 BO 3 ). Mix them evenly and place them in an agate mortar for thorough grinding for 30 min to obtain a mixture.

[0033] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter again at this temperature for 6 h, then cool it naturally to room temperature to obtain a sintered body.

[0034] (3) Grind the obtained sintered body sufficiently to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.985 Cr 0.015 O 7 .

[0035] Compared with Example 2, the luminescence intensity of the phosphor prepared in this example begins to decline.

[0036] Example 4

[0037] (1) Weigh each raw material according to the following weights: Weigh 0.3850 g of calcium carbonate (CaCO 3 ), 0.4025 g of zirconium oxide (ZrO 2 ), 0.8498 g of tantalum oxide (Ta 2 O 5 ), 0.3533 g of gallium oxide (Ga 2 O 3 ), 0.0058 g of chromium(III) oxide (Cr 2 O 3 ) and 0.04 g of boric acid (H 3 BO 3 ), mix them evenly, place them in an agate mortar and grind them sufficiently for 30 min to obtain a mixture.

[0038] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter it at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter it again at this temperature for 6 h, then cool it naturally to room temperature to obtain a sintered body.

[0039] (3) Grind the obtained sintered body sufficiently to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.98 Cr 0.02 O 7 .

[0040] Compared with Examples 2 and 3, the wavelength intensity of the phosphor prepared in this example continues to decline.

[0041] Example 5

[0042] (1) Weigh each raw material according to the following weights: Weigh 0.3850 g of calcium carbonate (CaCO 3 ), 0.4025 g of zirconium oxide (ZrO 2 ), 0.8498 g of tantalum oxide (Ta 2 O 5 ), 0.3515 g of gallium oxide (Ga 2 O 3 ), 0.3515 g of chromium(III) oxide (Cr 2 O 3) 0.0073 g and boric acid (H 3 BO 3 ) 0.04 g, mix them evenly, place them in an agate mortar and grind thoroughly for 30 min to obtain a mixture.

[0043] (2) Place the ground mixture powder in a small crucible, heat it at a heating rate of 5 °C / min to 900 °C, sinter at this temperature for 6 h, continue to heat at a heating rate of 5 °C / min to 1450 °C, and sinter again at this temperature for 6 h, then cool naturally to room temperature to obtain a sintered body.

[0044] (3) Grind the obtained sintered body thoroughly to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.975 Cr 0.025 O 7 .

[0045] Compared with the previous examples, the wavelength intensity of the phosphor prepared in this example continues to decrease.

[0046] Example 6

[0047] (1) Weigh each raw material according to the following weights: Weigh calcium carbonate (CaCO 3 ) 0.3850 g, zirconium oxide (ZrO 2 ) 0.4025 g, tantalum oxide (Ta 2 O 5 ) 0.8498 g, gallium oxide (Ga 2 O 3 ) 0.3496 g, chromium(III) oxide (Cr 2 O 3 ) 0.0088 g and boric acid (H 3 BO 3 ) 0.04 g, mix them evenly, place them in an agate mortar and grind thoroughly for 30 min to obtain a mixture.

[0048] (2) Place the ground mixture powder in a small crucible, heat it at a heating rate of 5 °C / min to 900 °C, sinter at this temperature for 6 h, continue to heat at a heating rate of 5 °C / min to 1450 °C, and sinter again at this temperature for 6 h, then cool naturally to room temperature to obtain a sintered body.

[0049] (3) Grind the obtained sintered body thoroughly to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.97 Cr 0.03 O 7 .

[0050] Compared with the previous examples, the wavelength intensity of the phosphor prepared in this example continues to decrease.

[0051] Example 7

[0052] (1) Weigh each raw material according to the following weights: Weigh calcium carbonate (CaCO 3 ) 0.3850 g, zirconium oxide (ZrO 2 ) 0.4025 g, tantalum oxide (Ta 2 O 5 ) 0.8498 g, gallium oxide (Ga 2 O 3 ) 0.3478 g, chromium(III) oxide (Cr 2 O 3 ) 0.0102 g, and boric acid (H 3 BO 3 ) 0.04 g. Mix them evenly and place them in an agate mortar for thorough grinding for 30 min to obtain a mixture.

[0053] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter it at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter it again at this temperature for 6 h. Then cool it naturally to room temperature to obtain a sintered body.

[0054] (3) Thoroughly grind the obtained sintered body to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.965 Cr 0.035 O 7 .

[0055] Compared with the previous examples, the wavelength intensity of the phosphor prepared in this example continues to decrease.

[0056] Example 8

[0057] (1) Weigh each raw material according to the following weights: Weigh calcium carbonate (CaCO 3 ) 0.3850 g, zirconium oxide (ZrO 2 ) 0.4025 g, tantalum oxide (Ta 2 O 5 ) 0.8498 g, gallium oxide (Ga 2 O 3 ) 0.3460 g, chromium(III) oxide (Cr 2 O 3 ) 0.0117 g, and boric acid (H 3 BO 3 ) 0.04 g. Mix them evenly and place them in an agate mortar for thorough grinding for 30 min to obtain a mixture.

[0058] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter it at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter it again at this temperature for 6 h, then cool it naturally to room temperature to obtain a sintered body.

[0059] (3) Grind the obtained sintered body thoroughly to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.96 Cr 0.04 O 7 .

[0060] Compared with the previous examples, the wavelength intensity of the phosphor prepared in this example continues to decrease.

[0061] Example 9

[0062] (1) Weigh each raw material according to the following weights: Weigh 0.3850 g of calcium carbonate (CaCO 3 ), 0.4025 g of zirconium oxide (ZrO 2 ), 0.8498 g of tantalum oxide (Ta 2 O 5 ), 0.3424 g of gallium oxide (Ga 2 O 3 ), 0.0146 g of chromium(III) oxide (Cr 2 O 3 ) and 0.04 g of boric acid (H 3 BO 3 ), mix them evenly, place them in an agate mortar and grind them thoroughly for 30 min to obtain a mixture.

[0063] (2) Place the ground mixture powder in a small crucible, heat it to 900 °C at a heating rate of 5 °C / min, sinter it at this temperature for 6 h, continue to heat it to 1450 °C at a heating rate of 5 °C / min, and sinter it again at this temperature for 6 h, then cool it naturally to room temperature to obtain a sintered body.

[0064] (3) Grind the obtained sintered body thoroughly to obtain a near-infrared phosphor with the chemical formula CaZrTaGa 0.95 Cr 0.05 O 7 .

[0065] Compared with the previous examples, the wavelength intensity of the phosphor prepared in this example continues to decrease.

[0066] Example 10 Detect the performance of the phosphor prepared in the example.

[0067] Experimental method:

[0068] Detect the phosphors CaZrTaGa prepared in Examples 1-60.995 Cr 0.005 O 7 (x = 0.005), CaZrTaGa 0.99 Cr 0.01 O 7 (x = 0.01), CaZrTaGa 0.985 Cr 0.015 O 7 (x = 0.015), CaZrTaGa 0.98 Cr 0.02 O 7 (x = 0.02), CaZrTaGa 0.975 Cr 0.025 O 7 (x = 0.025) and CaZrTaGa 0.97 Cr 0.03 O 7 (x = 0.03) and the X-ray diffraction patterns of the standard samples, as Figure 1 shown.

[0069] The excitation and emission spectra of CaZrTaGa prepared in Example 2 0.99 Cr 0.01 O 7 are as shown in Figure 2 The figure, where the excitation wavelength λ ex = 461 nm and the emission wavelength λ em = 785 nm.

[0070] Detect the phosphors CaZrTaGa prepared in Examples 1 - 9 0.995 Cr 0.005 O 7 (x = 0.005), CaZrTaGa 0.99 Cr 0.01 O 7 (x = 0.01), CaZrTaGa 0.985 Cr 0.015 O 7 (x = 0.015), CaZrTaGa 0.98 Cr 0.02 O 7 (x = 0.02), CaZrTaGa 0.975 Cr 0.025 O 7 (x = 0.025), CaZrTaGa 0.97 Cr 0.03 O 7 (x = 0.03), CaZrTaGa 0.965 Cr 0.035 O 7(x = 0.035), CaZrTaGa 0.96 Cr 0.04 O 7 (x = 0.04) and CaZrTaGa 0.95 Cr 0.05 O 7 (x = 0.05) emission spectra, the results are as Figure 3 shown. It can be seen from Figure 3 that the luminescence intensity of the near-infrared phosphors prepared in Examples 1-5 is relatively strong; and the luminescence intensity of the near-infrared phosphors prepared in Examples 1-3 is relatively stronger; in particular, the luminescence intensity of the phosphor prepared in Example 2 is the strongest.

Claims

1. A near-infrared phosphor, characterized in that: Its general chemical formula is: CaZrTaGa 1-x Cr x O7, where 0<x≤0.

05.

2. The near-infrared phosphor according to claim 1, characterized in that: The value range of x is 0.005≤x≤0.

05.

3. The near-infrared phosphor according to claim 2, characterized in that: The value range of x is 0.005≤x≤0.

02.

4. The near-infrared phosphor according to claim 3, characterized in that: x＝0.01。 5. A method for preparing near-infrared phosphor, characterized in that: The steps include: (a) According to the chemical formula of phosphor CaZrTaGa 1-x Cr x The molar ratio of each element in O7 is to weigh oxides or carbonates containing Ca, Zr, Ta, Ga, and Cr elements, add boric acid to the weighed raw materials, mix, grind, and obtain a mixture, wherein 0<x≤0.05 in the chemical formula; (b) heating the mixture in step (a) to 900° C. and calcining for 6 h, then continuing to heat to 1450° C. and calcining for 6 h, and cooling to room temperature to obtain a sintered body; (c) The obtained sintered body is fully ground to obtain near-infrared phosphor CaZrTaGa 1-x Cr x O7.

6. The method for preparing the near-infrared phosphor according to claim 5, characterized in that: The grinding time in step (a) is 15-30 min.

7. The method for preparing the near-infrared phosphor according to claim 5, characterized in that: The heating rate in step (b) is 5-10°C / min.

8. The method for preparing near-infrared phosphor according to claim 5, characterized in that: In step (a), oxides or carbonates containing Ca, Zr, Ta, Ga, and Cr elements are weighed, specifically: CaCO3, ZrO2, Ta2O5, Ga2O3, and Cr2O3 are weighed.

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