WO2023165081A1 - Broadband near-infrared fluorescent powder based on spinel structure, preparation method therefor and application thereof - Google Patents

Abstract

Disclosed in the present invention are a broadband near-infrared fluorescent powder based on a spinel structure, a preparation method therefor and an application thereof. The chemical formula of the broadband near-infrared fluorescent powder is A_x(B_1-yC_y)₂O₄:zCr³⁺, wherein A is one or more of Mg, Zn, Ca, Sr, Ba, and Be elements, B is one or more of Ga, Al, Sc, In, Y, La, and Lu elements, C is one or more of Si, Sn, In, Ta, As, Li, Na, and K elements, 0.4≤x≤1.2, 0.01<y<0.50, and 0.01<z<0.20. The method comprises: uniformly mixing the raw materials to obtain a uniform mixture, calcining the uniform mixture in a high temperature furnace having an atmosphere, or adding a fluxing agent, cooling the calcined product, and grinding, sieving and washing the calcined product to obtain the broadband near-infrared fluorescent powder. The fluorescent powder prepared in the present invention has the advantages of wide emission wavelength coverage range, high luminous intensity, low thermal quenching, good physicochemical stability, etc., and is widely applied as a near-infrared light conversion material.

Description

Broadband near-infrared phosphor based on spinel structure and its preparation method and application technical field

The invention belongs to a fluorescent powder and its preparation method and application in the technical field of luminescent materials, and specifically relates to a broadband near-infrared fluorescent powder based on a spinel structure and its preparation method and application.

Background technique

Near-infrared light sources with emission wavelengths between 650 and 1700 nm are widely used, such as near-infrared (NIR) spectrometers, optical coherence tomography systems, and solar simulators. Especially in NIR spectroscopy, since the vibrational frequency doubling and combined frequency of hydrogen-containing groups (O-H, N-H, C-H) in some functional groups are in the near-infrared region, by scanning the near-infrared spectrum of the sample, it can be analyzed. Characteristic information of hydrogen-containing groups. Combining NIR spectroscopy technology with non-destructive diagnosis and analysis functions with rising portable smart terminal devices (such as mobile phones and smart watches) is expected to realize instant analysis of food, medicine, clothing, etc. in daily life and human health. Status real-time monitoring. As one of the core components of NIR spectroscopy technology, traditional broadband near-infrared light sources are not only inefficient, but also large in size, which cannot meet the needs of integration.

One way to obtain a miniature broadband NIR light source is through the integration of multi-band LED NIR chips to achieve broadband NIR emission. For example, patent document CN103156620A discloses a near-infrared spectral imaging system that uses a combination of dozens of chips to realize ultra-broadband emission (650-1700nm). However, due to the need to design complex circuits to control the driving voltage and driving current of each chip, the technical difficulty is high, the cost is high, and the spectral stability is poor. Fluorescent conversion NIR LEDs based on high-efficiency, low-cost blue LED chips and NIR fluorescent conversion materials have many advantages such as low price, simple structure, small size, and stable spectrum. However, as a key part of fluorescent conversion NIR LEDs, NIR fluorescent conversion materials (phosphors) still have problems such as narrow emission spectrum range, low quantum efficiency, and poor thermal stability that need to be solved urgently.

Patent document CN109913214A discloses a NIR phosphor composed of R _x Al _1-y F _x+3 :yCr, whose emission range is 700-900nm; non-patent document Adv.Optical Mater.2020,8,2000296 publishes The NIR fluorescent powder composed of Gd ₃ Sc _2-x Al _x Ga ₃ O ₁₂ : Cr ³⁺ can emit 650-900nm, its internal quantum efficiency is close to 100%, and the emission intensity still maintains 87% of the initial value at 150°C above. Although these phosphors have excellent luminescent properties, their emission wavelength coverage is narrow and cannot meet the needs of NIR spectroscopy alone. For example, the characteristic absorption of water that is common in life is around 970nm. Another example is the non-patent literature ACS Energy Letters, 2018, 3, 2679-2684, which announced that the composition of La ₃ Ga ₅ GeO ₁₄ : Cr ³⁺ can emit NIR phosphors covering 650-1200 nm, although the half-maximum width of the emission band is as high as 300nm, which can meet the requirements of NIR spectrum technology for the spectrum range, but its internal quantum efficiency is extremely low (<30%), so the NIR output efficiency of the corresponding fluorescence conversion NIRLED device is low.

Therefore, the prior art lacks a low-cost, high-efficiency, and high-thermal-stability ultra-broadband NIR phosphor to construct a high-performance miniature broadband NIR light source.

Contents of the invention

In order to solve the problems existing in the background technology, the object of the present invention is to provide a kind of broadband near-infrared phosphor based on spinel structure; another object of the present invention is to provide the preparation method and application of the above-mentioned broadband near-infrared phosphor . The invention prepares ultra-broadband NIR fluorescent powder with low cost, high efficiency and high thermal stability, and then constructs a high-performance miniature broadband NIR light source.

To achieve the above object, the technical scheme of the present invention is as follows:

1. A broadband near-infrared phosphor:

The broadband near-infrared fluorescent powder is an inorganic compound, and its chemical formula is A _x (B _{1-y Cy} ) ₂ O ₄ :zCr ³⁺ , wherein A is Mg, Zn, Ca, Sr, Ba, Be element One or more of, B is one or more of Ga, Al, Sc, In, Y, La, Lu elements, C is Si, Sn, In, Ta, As, Li, Na, K elements One or more of , and the parameters x, y, z meet the following conditions:

0.4≤x≤1.2, 0.01<y<0.50, 0.01<z<0.20.

The main crystal phase of the broadband near-infrared phosphor has a spinel structure.

The fluorescent powder is effectively excited by visible light with a wavelength range of 400-700nm, and emits near-infrared light with a wavelength range of 650-1300nm.

Two, a preparation method of the broadband near-infrared fluorescent powder as claimed in claim 1, comprising the following steps:

(1) According to the stoichiometric ratio described in claim 1, the compound containing A, B, C and Cr is weighed respectively as a raw material, and A is one or more of Mg, Zn, Ca, Sr, Ba, Be elements , B is one or more of Al, Ga, Sc, In, Y, La, Lu elements, C is one or more of Si, Ge, Sn, In, Ta, As, Li, Na, K elements Various, and then fully mix the raw materials evenly to obtain a uniform mixture;

(2) directly roasting the obtained homogeneous mixture or the homogeneous mixture with flux added at 1200-1600°C for 2-20 hours in a high-temperature furnace with an atmosphere;

(3) After the calcined product is cooled, it is ground, sieved and washed to obtain the broadband near-infrared phosphor.

In the step (1), the compound is one or more of oxides, nitrates, halides, and carbonates containing corresponding elements.

The heat treatment of calcination is carried out in the step (2), and the heat treatment time is 2 to 20 hours.

The flux is specifically: one or more of H ₃ BO ₃ , MgF ₂ , CaF ₂ , Li ₂ CO ₃ , PbO, BaF ₂ , PbF ₂ , KF, LiF, and the content is the overall mass of the homogeneous mixture 1-30% of.

In the step (2), the atmosphere is at least one of air, oxygen, hydrogen, nitrogen and hydrogen mixed gas, argon and hydrogen mixed gas or carbon monoxide gas.

3. A fluorescent conversion LED device, which is a broadband near-infrared phosphor made by the above preparation method.

The LED device includes a light source and a fluorescent conversion material, and the broadband near-infrared phosphor is used to prepare the fluorescent conversion material.

The light source includes an LED chip, a laser diode or an organic EL light emitting device whose emission wavelength is between 400nm and 700nm.

The invention can emit light in the range of 650-1300nm under the excitation of 400-700nm visible light.

Preferably, the light source is a semiconductor chip with an emission peak of 400-700 nm, and preferably a near-ultraviolet or blue LED chip with an emission wavelength of 400-500 nm, or a red light chip with an emission wavelength of 600-700 nm.

More preferably, the fluorescent powder is mixed with glue and then packaged on a blue LED chip emitting 400-500 nm to finally prepare a fluorescent conversion type broadband near-infrared light source.

The phosphor powder prepared by the present invention has the advantages of wide emission wavelength coverage, high luminous intensity, low thermal quenching, and good physical and chemical stability, so it can be used as a near-infrared light conversion material for night vision, food analysis, and material detection. , medical imaging, simulated solar spectrum and other fields.

Beneficial effects of the present invention: Compared with the prior art, the present invention has the following significant advantages:

1. The single doping of Cr ³⁺ in the phosphor powder of the present invention can obtain the broadband near-infrared light of 650-1300nm and the half-maximum width greater than 300nm under the excitation of blue light and red light with a wavelength range of 400-700nm. Phosphor powder has high luminous efficiency and good thermal stability.

2. The preparation method of the phosphor powder of the present invention is simple and easy to operate, and can be constructed into a miniature broadband near-infrared light source by combining with a visible light LED chip or a laser diode.

Description of drawings

Fig. 1 is the XRD collection of illustrative plates of the sample prepared in embodiment 1;

Fig. 2 is the excitation spectrum of the sample prepared in embodiment 1;

Fig. 3 is the emission spectrum of the sample prepared by embodiment 1, 2, 4, 7 and comparative example 1;

Fig. 4 is the spectrum of the device packaged with the samples prepared in Examples 1, 2, and 4 combined with a 450nm blue LED.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific implementation.

Embodiments of the present invention are as follows:

Example 1

Its chemical formula is Mg _0.9 (Al _0.95 Si _0.05 ) ₂ O ₄ :0.1Cr ³⁺ and its preparation steps are as follows:

1. Weigh MgO, Al ₂ O ₃ , Cr ₂ O ₃ , and 3wt% flux H ₃ BO ₃ , grind and stir them in an agate mortar for about 30 minutes, and finally mix them evenly.

2. Sinter the homogeneously mixed raw materials at 1350°C for 2 hours under a mixed atmosphere of hydrogen, nitrogen and hydrogen containing 5vol% hydrogen to obtain a roasted product

3. The roasted product is the broadband near-infrared phosphor of the present invention after being fully ground, washed and sieved.

As shown in FIG. 1 , the main crystal phase of the sample prepared in Example 1 belongs to cubic spinel.

As shown in FIG. 2 and FIG. 3 , the sample prepared in Example 1 emits broadband near-infrared light under the excitation of visible light in the range of 400-700 nm.

As shown in Figure 4, the sample prepared in Example 1 can be combined with a 450nm blue LED to package a fluorescence conversion broadband near-infrared LED device, so it can be applied to near-infrared spectroscopy, solar simulators and other related fields.

The internal quantum efficiency of the fluorescent powder in this embodiment is 85%, and its integrated emission intensity still maintains 72% at 150° C. compared with room temperature.

Example 2

Except that the molecular formula was changed to Mg _0.8 (Al _0.8 Si _0.2 ) ₂ O ₄ :0.1Cr ³⁺ and the sintering temperature was changed to 1400°C and kept for 5 hours, other preparation steps and process conditions were the same as in Example 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Embodiment 1, and the emission spectrum is shown in FIG. 3 .

The internal quantum efficiency of the fluorescent powder in this embodiment is 80%, and its integrated emission intensity still maintains 75% at 150° C. compared with room temperature.

Example 3

Except that the molecular formula was changed to Zn _0.7 [(Ga _0.9 Al _0.1 ) _0.7 Si _0.3 ] ₂ O ₄ :0.1Cr ³⁺ and the sintering temperature was changed to 1250°C and held for 7 hours, other preparation steps and process conditions were the same as in Example 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Example 1, and the emission spectrum is similar to that of Example 2.

The internal quantum efficiency of the fluorescent powder in this embodiment is 75%, and its integrated emission intensity still maintains 70% at 150° C. compared with room temperature.

Example 4

Except that the components in Example 3 were changed to Mg _0.8 (Ga _0.45 Al _0.45 Si _0.1 ) ₂ O ₄ :0.02Cr ³⁺ , other preparation steps and process conditions were the same as in Example 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Embodiment 1, and the emission spectrum is shown in FIG. 3 .

The internal quantum efficiency of the fluorescent powder in this embodiment is 92%, and its integrated emission intensity still maintains 85% at 150° C. compared with room temperature.

Example 5

Except that the composition in Example 1 was changed to Mg(Ga _0.9 Si _0.1 ) ₂ O ₄ :0.1Cr ³⁺ and the sintering temperature was changed to 1350°C and held for 7 hours, other preparation steps and process conditions were the same as in Example 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Example 1, and the emission spectrum is similar to that of Example 2.

The internal quantum efficiency of the fluorescent powder in this embodiment is 83%, and its integrated emission intensity still maintains 80% at 150° C. compared with room temperature.

Example 6

Except that the composition in Example 1 was changed to (Mg _0.9 Sr _0.2 )(Ga _0.7 Ge _0.1 Li _0.2 ) ₂ O ₄ :0.08Cr ³⁺ and the sintering temperature was changed to 1550°C and held for 7 hours, other preparation steps and processes The conditions are the same as in Example 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Example 1, and the emission spectrum is similar to that of Example 2.

The internal quantum efficiency of the fluorescent powder in this embodiment is 87%, and its integrated emission intensity still maintains 78% at 150° C. compared with room temperature.

Example 7

Except that the composition of Example 6 was changed to (Mg _0.8 Ca _0.1 )(Al _0.5 Ga _0.1 Si _0.1 K _0.3 ) ₂ O ₄ :0.06Cr ³⁺ and the sintering temperature was changed to 1550°C and held for 7 hours, other preparation steps and Processing condition is identical with embodiment 1. The XRD spectrum and excitation spectrum of this embodiment are similar to those of Embodiment 1, and the emission spectrum is shown in FIG. 3 .

The internal quantum efficiency of the fluorescent powder in this embodiment is 82%, and its integrated emission intensity still maintains 80% at 150° C. compared with room temperature.

Embodiment 8 to embodiment 20:

According to the embodiment chemical formula composition and stoichiometric ratio in Table 1, take corresponding raw materials, its heat treatment temperature and atmosphere are shown in Table 1, and other steps are all the same as above-mentioned embodiment.

Table 1 Example 5-10

Comparative example 1

The phosphor powder described in this embodiment has a chemical composition of MgAl _1.98 Cr _0.02 O ₄ . According to their stoichiometric ratio, accurately weigh MgO, Al ₂ O ₃ and Cr ₂ O ₃ , and 3wt% flux H ₃ BO ₃ , after grinding and mixing, place the mixed raw materials in a high-temperature furnace containing 5vol% hydrogen Sintering at 1350° C. for 5 hours in a hydrogen-nitrogen-hydrogen mixed atmosphere to obtain a roasted product; after crushing and grinding the obtained roasted product, a phosphor powder belonging to a spinel structure can be obtained. The luminescent performance of the obtained phosphor was analyzed by a fluorescence spectrometer, and under the excitation of 450nm blue light, a narrow-band dark red light emission with an emission peak at 689nm was obtained.

As shown in Figure 3, comparing the emission spectra of Examples 1, 2, 4, 7 and Comparative Example 1, under the same wavelength of blue light excitation, the emission peak of the emission spectrum in the embodiment is obviously red-shifted, and the spectrum is half The height and width gradually increase, while the comparative example only emits narrow-band dark red light.

As shown in FIG. 4 , the spectra of the devices in Examples 1, 2, and 4 combined with 450nm blue LED packages can achieve a large wavelength coverage and an adjustable peak wavelength.

As can be seen from the above examples, although the phosphor powder described in the present invention has the same crystal structure as the traditional aluminate or gallate spinel, it is only found that the specific element pair Cr is introduced into the spinel structure at the same time ^{. +} Ion lattice substitution distribution and local crystal field can be adjusted to achieve Cr ³⁺ efficient broadband near-infrared emission, which also shows that compared with the invention without introducing other elements, the technology disclosed in the present invention has significant advantages. progress.

Apparently, the above-mentioned embodiment is only an example for the sake of clear description, other forms of changes or changes can also be made on the basis of the above description, and the obvious changes or changes derived therefrom still belong to the protection scope of the present invention within. The preparation of the phosphor powder in the embodiment of the present invention adopts the solid phase sintering method, however, its preparation method is not limited to this, and other methods that can fully react the raw materials can obtain the phosphor powder described in the present invention. For example, spray pyrolysis method, combustion method, microwave-assisted heating method, precipitation method, hydrothermal method, sol-gel method, etc. The raw materials used in the embodiments of the present invention can also use other compounds that contain corresponding elements but do not introduce foreign impurities.

Claims (10)

1. A broadband near-infrared phosphor, characterized in that:

   The broadband near-infrared fluorescent powder is an inorganic compound, and its chemical formula is A _x (B _{1-y Cy} ) ₂ O ₄ :zCr ³⁺ , wherein A is Mg, Zn, Ca, Sr, Ba, Be element One or more of, B is one or more of Ga, Al, Sc, In, Y, La, Lu elements, C is Si, Sn, In, Ta, As, Li, Na, K elements One or more of , and the parameters x, y, z meet the following conditions:

   0.4≤x≤1.2, 0.01<y<0.50, 0.01<z<0.20.
2. The broadband near-infrared phosphor according to claim 1, wherein the main crystal phase of the broadband near-infrared phosphor has a spinel structure.
3. The broadband near-infrared phosphor according to claim 1, wherein the phosphor is effectively excited by visible light with a wavelength range of 400-700 nm, and emits near-infrared light in the range of 650-1300 nm.
4. A preparation method of the broadband near-infrared fluorescent powder according to claim 1, characterized in that, comprising the following steps:

   (1) According to the stoichiometric ratio described in claim 1, the compound containing A, B, C and Cr is weighed respectively as a raw material, and A is one or more of Mg, Zn, Ca, Sr, Ba, Be elements , B is one or more of Al, Ga, Sc, In, Y, La, Lu elements, C is one or more of Si, Ge, Sn, In, Ta, As, Li, Na, K elements Various, and then fully mix the raw materials evenly to obtain a uniform mixture;

   (2) directly roasting the obtained homogeneous mixture or the homogeneous mixture with flux added at 1200-1600°C for 2-20 hours in a high-temperature furnace with an atmosphere;

   (3) After the calcined product is cooled, it is ground, sieved and washed to obtain the broadband near-infrared phosphor.
5. The preparation method of broadband near-infrared phosphor powder according to claim 4, is characterized in that:

   In the step (1), the compound is one or more of oxides, nitrates, halides, and carbonates.
6. The preparation method of broadband near-infrared phosphor powder according to claim 4, is characterized in that:

   The flux is specifically: one or more of H ₃ BO ₃ , MgF ₂ , CaF ₂ , Li ₂ CO ₃ , PbO, BaF ₂ , PbF ₂ , KF, LiF, and the content is the overall mass of the homogeneous mixture 1-30% of.
7. The preparation method of broadband near-infrared phosphor powder according to claim 4, is characterized in that:

   In the step (2), the atmosphere is at least one of air, oxygen, hydrogen, nitrogen and hydrogen mixed gas, argon and hydrogen mixed gas or carbon monoxide gas.
8. A fluorescent conversion type LED device is characterized in that it is a broadband near-infrared fluorescent powder made by the preparation method described in any one of claims 2-6.
9. The application of the broadband near-infrared phosphor powder in the preparation of fluorescent conversion LED devices according to claim 1, wherein the LED device comprises a light source and a fluorescent conversion material, and the broadband near-infrared phosphor powder is used to prepare Fluorescence conversion material.
10. The application according to claim 9, wherein the light source comprises an LED chip, a laser diode or an organic EL light emitting device with an emission wavelength between 400nm and 700nm.

Images