CN113481006B - Near infrared broad spectrum fluorescent material and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of luminescent materials, in particular to a near-infrared wide-spectrum fluorescent material and a preparation method and application thereof. The invention discloses a near-infrared wide-spectrum fluorescent material, which has the chemical formula shown in formula (I): (M ¹ _1‑m Cr _m )M ² O ₄ formula (I); wherein, M ¹ is selected from Al, Ga, Sc or In, and must contain Al and/or Ga; ^M2 element is selected from Ta or Nb; 0.0001≤m≤0.1. The fluorescent material selects the M ¹ M ² O ₄ matrix material with a rigid structure for Cr ³⁺ ion doping, and develops a material that can be excited by 460nm blue light with high efficiency, the emission peak is located at 820-920nm and can be continuously changed, and the luminous efficiency is high. .

Description

A kind of near-infrared wide-spectrum fluorescent material and its preparation method and application

technical field

The invention relates to the technical field of luminescent materials, in particular to a near-infrared wide-spectrum fluorescent material and a preparation method and application thereof.

Background technique

Compared with traditional near-infrared light sources, near-infrared light-emitting diodes (pc-NIR-LEDs) based on fluorescence conversion have the advantages of low cost, good stability, and easy regulation, and are widely used in biological imaging, food quality inspection, night vision monitoring and other fields. . Its specific applications can be divided according to the wavelength. For example, in the field of biological imaging, near-infrared light of 650-950nm and 1000-1400nm can penetrate deep tissues and generate an autofluorescence background of zero phonons, making near-infrared biological imaging low-confidence. noise ratio and high sensitivity. In the field of food detection, the food is irradiated with near-infrared light with a wavelength covering 650-1050nm, and the composition and content of the compound in the food can be determined according to the absorption of specific wavelengths to achieve non-contact non-destructive food detection. 830nm and 940nm near-infrared light can be applied to night vision cameras. In addition, 850nm near-infrared light can be applied to iris, face recognition and AR/VR (augmented/virtual reality) technology; 940nm near-infrared light can be applied to the detection of blood oxygen content. It can be seen that pc-NIR-LED is playing an increasingly important role in modern life and advanced technology, and near-infrared fluorescent conversion materials have become the key materials that determine its application range and performance.

At present, the near-infrared broad-spectrum phosphor activated by Cr ³⁺ has been widely studied because of its high efficiency and other advantages, but there are still some problems in the performance of this material. For example, for the developed materials, most of the peak wavelengths are concentrated within 800nm, and there are few materials larger than 800nm; there are few materials with internal quantum efficiencies higher than 80% and the emission peak wavelengths are all less than 800nm, and the external quantum efficiency is generally lower than 35%; Materials with peak wavelength greater than 800nm have poor thermal stability and generally low internal quantum efficiency (<80%). These problems seriously restrict the application of near-infrared fluorescence conversion materials. Therefore, exploring and developing high-efficiency near-infrared broad-spectrum materials with a peak wavelength greater than 800 nm is an urgent internal demand for the development of near-infrared fluorescent conversion LED devices, and is of great significance.

Contents of the invention

In view of this, the present invention provides a near-infrared wide-spectrum fluorescent material and its preparation method and application. The excitation peak wavelength of the fluorescent material is located in the 450-480nm band, the emission peak wavelength is located in the 820-900nm and can be continuously changed, and the luminous efficiency High, which can meet the requirements for the development of wide-spectrum near-infrared LED devices.

Its specific technical scheme is as follows:

The invention provides a near-infrared wide-spectrum fluorescent material, which has a chemical formula shown in formula (I);

(M ¹ _1-m Cr _m )M ² O ₄ formula (I);

In total, M ¹ is selected from Al, Ga, Sc or In, and must contain Al and/or Ga; M ² is selected from Ta or Nb; 0.0001≤m≤0.1.

In the present invention, the M ¹ is preferably Ga; the M ² is Ta; m is preferably: 0.001≤m≤0.05.

The present invention also provides a preparation method of a near-infrared wide-spectrum fluorescent material, comprising the following steps:

Grinding the ^M1 -containing compound, the ^M2 -containing compound and the Cr-containing compound, mixing them, and sintering to obtain a near-infrared wide-spectrum fluorescent material;

The near-infrared broad-spectrum fluorescent material has a chemical formula shown in formula (I);

(M ¹ _1-m Cr _m )M ² O ₄ formula (I);

In total, M ¹ is selected from Al, Ga, Sc or In, and must contain Al and/or Ga; M ² is selected from Ta or Nb; 0.0001≤m≤0.1.

In the present invention, the M1 ^- containing compound is selected from one or more of aluminum oxide, aluminum hydroxide, aluminum nitrate, gallium oxide, gallium nitrate, scandium oxide, scandium nitrate, indium oxide and indium hydroxide;

The ^M2 -containing compound is tantalum oxide and/or niobium oxide;

The Cr compound is chromium oxide or chromium nitrate.

In the present invention, the sintering is carried out in air, the temperature of the sintering is 1200-1500° C., and the time is 4-12 hours;

After the sintering, it also includes: crushing and grinding the sintered product.

The present invention also provides a near-infrared broad-spectrum fluorescent material or an application of the above-mentioned near-infrared broad-spectrum fluorescent material in a wide-spectrum near-infrared LED device.

In the present invention, the optically active element Cr ³⁺ is dissolved in M ¹ M ² O ₄ (M ¹ =Al, Ga, Sc or In, and must contain Al and/or Ga; M ² =Ta or Nb) crystal phase, when When the components contain Al or Ga, a brand new material system with high luminous efficiency can be obtained with the excitation peak wavelength in the 450-480nm band and the emission peak wavelength in the 820-900nm band. It belongs to a new structure and a new component compound, and has potential application value.

The present invention relates to Cr ³⁺ alone doped M ¹ M ² O ₄ (M ¹ =Al, Ga, Sc or In, and must contain Al and/or Ga; M ² =Ta or Nb), or on this basis, The fluorescent materials with new components formed by changing the composition of Ta/Nb and the ratio of Al/Ga/Sc/In, as well as the mixture containing the above components as the main components, all belong to the scope of this patent. However, considering the efficiency of luminescence, M in the fluorescent material of the present invention is ^preferably Ga. The purpose is to emphasize that the composition containing Ga is compared to the composition containing Al, Sc or In alone and the composition containing Al, Sc or In. The components formed have higher luminous efficiency; preferably ^M2 is Ta, the purpose is to emphasize that the components containing Ta have higher luminous efficiency than the components containing Nb.

The near-infrared broad-spectrum fluorescent material provided by the present invention can realize the control of luminous peak position and luminous efficiency by changing the composition of Ta/Nb and adjusting the ratio of Al/Ga/Sc/In. The optimized luminous efficiency can reach 90%, far exceeding the existing material system, and has great application potential.

As can be seen from the above technical solutions, the present invention has the following advantages:

1. The excitation peak wavelength of the near-infrared broad-spectrum fluorescent material provided by the present invention is 450-480nm, which is suitable for excitation by blue LED chips and has strong practicability.

2. The near-infrared broad-spectrum fluorescent material provided by the present invention can efficiently emit near-infrared light with a peak wavelength of about 820-920nm under the excitation of 460nm blue light, and can be used as a broad-spectrum fluorescent powder for near-infrared LEDs with fluorescence conversion.

3. The raw materials of the near-infrared broad-spectrum fluorescent material provided by the present invention are cheap and easy to obtain, and the synthesis temperature is low, the preparation process is simple, no special reaction equipment is required, and industrial production is convenient.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative efforts.

Fig. 1 is _the X-powder diffraction pattern of Ga _0.998 Cr _0.002 TaO in Example 1 of the present invention;

Fig. 2 is _the excitation spectrum of Ga _0.998 Cr _0.002 TaO in Example 1 of the present invention;

Fig. 3 is _the emission spectrum of Ga _0.998 Cr _0.002 TaO in Example 1 of the present invention;

Fig. 4 is _the excitation spectrum of Al _0.99 Cr _0.01 TaO in Example 2 of the present invention;

Fig. 5 is the emission spectrum of Al _0.99 Cr _0.01 TaO ₄ in Example 2 of the present invention.

Detailed ways

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the embodiments described below are only part of the implementation of the present invention example, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

Weigh 0.0499mol Ga ₂ O ₃ , 0.0001mol Cr ₂ O ₃ , 0.05mol Ta ₂ O ₅ according to the chemical formula of phosphor powder Ga _0.998 Cr _0.002 TaO ₄ , the above raw materials are analytically pure, weigh the above raw materials and grind them thoroughly , after mixing evenly, put it into an alumina crucible and bake it at 1450°C for 12 hours. After cooling to room temperature, the product is crushed, ground, washed and other post-treatments are obtained to obtain a phosphor powder with a chemical composition of Ga _0.998 Cr _0.002 TaO ₄ , and its X-powder diffraction pattern (Cu target, λ=0.15406nm) is similar to that of the GaTaO ₄ standard The card comparison is shown in Figure 1, and its excitation spectrum (under 840nm monitoring) is shown in Figure 2. It can be seen from Figure 1 that Ga _0.998 Cr _0.002 TaO ₄ was successfully produced in this example; it can be seen from Figure 2 that the phosphor can be effectively excited by blue light and red light in the range of 400-800nm, and the main excitation peak is located at 470nm. Fig. 3 is the emission spectrum of Ga _0.998 Cr _0.002 TaO ₄ in this embodiment. It can be seen from Fig. 3 that the emission spectrum covers 700-1100nm, and its main emission peak is located at 840nm. Under the excitation of 460nm blue light, the quantum yield reaches 92% (see Table 1).

Example 2

Weigh 0.0495mol Al ₂ O ₃ , 0.0005mol Cr ₂ O ₃ , 0.05mol Ta ₂ O ₅ according to the chemical formula of phosphor powder Al _0.99 Cr _0.01 TaO ₄ , the above raw materials are analytically pure, weigh the above raw materials and grind them thoroughly , after mixing evenly, put it into an alumina crucible and bake at 1300°C for 8 hours. After cooling to room temperature, the product is crushed, ground, washed and other post-treatments are obtained to obtain a phosphor powder with a chemical composition of Al _0.99 Cr _0.01 TaO ₄ , and its excitation spectrum (under 900nm monitoring) is shown in Figure 4, from which it can be seen that the phosphor The powder can be effectively excited by blue light and red light in the range of 400-800nm, and the main excitation peak is located at 645nm. Fig. 5 is the emission spectrum of Al _0.99 Cr _0.01 TaO ₄ in this embodiment. It can be seen from Fig. 5 that the emission spectrum covers 700-1300nm, and its main emission peak is located at 900nm. Under the excitation of 460nm blue light, the quantum yield is 80% (see Table 1).

Example 3

Weigh 0.04999mol Ga ₂ O ₃ , 0.000005mol Cr ₂ O ₃ , 0.05mol Nb ₂ O ₅ according to the chemical formula of phosphor powder Ga _0.9998 Cr _0.0001 NbO ₄ , the above raw materials are analytically pure, weigh and mix the above raw materials and grind them thoroughly , after mixing evenly, put it into an alumina crucible and bake at a temperature of 1500° C. for 4 hours. After cooling to room temperature, the product is crushed, ground, washed and other post-treatments are obtained to obtain a phosphor powder with a chemical composition of Ga _0.9998 Cr _0.0001 NbO _{4 .} Blue light and red light in the range of 800nm are effectively excited, and the main excitation peak is located at 468nm. Under the excitation of 460nm blue light, the emission spectrum of Ga _0.9998 Cr _0.0001 NbO ₄ covers 700-1100nm, its main emission peak is located at 838nm, and the quantum yield is 75% (see Table 1).

Example 4

Weigh 0.094mol Al(OH) ₃ , 0.003mol Cr ₂ O ₃ , 0.05mol Nb ₂ O ₅ according to the chemical formula of phosphor powder Al _0.94 Cr _0.06 NbO ₄ . After grinding and mixing evenly, put it into an alumina crucible and bake it at 1200°C for 8 hours. After cooling to room temperature, the product is crushed, ground, washed and other post-treatments are obtained to obtain a phosphor powder with a chemical composition of Al _0.94 Cr _0.06 NbO ₄ . The red light is effectively excited, and the main excitation peak is located at 670nm. Under the excitation of 460nm blue light, the emission spectrum of Al _0.94 Cr _0.06 NbO ₄ covers 700-1300nm, its main emission peak is located at 895nm, and the quantum yield is 60% (see Table 1).

Example 5

Weigh 0.02mol Al ₂ O ₃ , 0.026Ga ₂ O ₃ , 0.0004mol Cr ₂ O ₃ , 0.05mol Ta ₂ O ₅ according to the chemical formula of phosphor powder Al _0.4 Ga _0.52 Cr _0.008 TaO ₄ . The above-mentioned raw materials are weighed and blended and fully ground, and after being mixed evenly, they are put into an alumina crucible and roasted at a temperature of 1400° C. for 10 hours. After cooling to room temperature, the product is crushed, ground, washed and other post-treatments are obtained to obtain a phosphor with a chemical composition of Al _0.4 Ga _0.52 Cr _0.008 TaO ₄ , and its excitation spectrum (under 900nm monitoring) covers the range of 400-800nm, which can be Blue light and red light in the range of 400-800nm are effectively excited, and the main excitation peak is located at 470nm. Under the excitation of 460nm blue light, the emission spectrum of Al _0.4 Ga _0.52 Cr _0.008 TaO ₄ covers 700-1300nm, the main emission peak is at 900nm, and the quantum yield is 72% (see Table 1).

Example 6

The chemical formula of the phosphor powder prepared by the method of Example 5 is expressed as: Ga _0.6 Sc _0.38 Cr _0.02 TaO ₄ , and the emission peak wavelength and quantum yield of the phosphor powder obtained are shown in Table 1.

Example 7

The chemical formula of the phosphor powder prepared by the method of Example 5 is expressed as: Ga _0.7 In _0.25 Cr _0.05 TaO ₄ , and the emission peak wavelength and quantum yield of the phosphor powder obtained are shown in Table 1.

Example 8

The chemical formula of the phosphor powder prepared by the method of Example 5 is expressed as: Al _0.8 In _0.12 Cr _0.08 Ta _0.5 Nb _0.5 O ₄ , and the emission peak wavelength and quantum yield of the phosphor powder obtained are shown in Table 1.

Example 9

The chemical formula of the phosphor powder prepared by the method of Example 5 is expressed as: Al _0.2 Ga _0.794 Cr _0.006 Ta _0.2 Nb _0.8 O ₄ , and the emission peak wavelength and quantum yield of the phosphor powder obtained are shown in Table 1.

Example 10

The chemical formula of the phosphor powder prepared by the method of Example 5 is expressed as: Al _0.5 Sc _0.4 Cr _0.1 Ta _0.8 Nb _0.2 O ₄ , and the emission peak wavelength and quantum yield of the phosphor powder obtained are shown in Table 1.

The emission peak position and quantum yield of the fluorescent powder of the embodiment 1-10 of table 1 under 460nm excitation

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still understand the foregoing The technical solutions recorded in each embodiment are modified, or some of the technical features are replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (6)

1. A near infrared broad spectrum fluorescent material is characterized by having a chemical formula shown in a formula (I); (M) ¹ _1-m Cr _m )M ² O ₄ Formula (I);

wherein M is ¹ Selected from Ga, sc, and necessarily comprising Ga; m is M ² The element is Ta; wherein when M ¹ When selected from Ga, m=0.002, and has the chemical formula Ga _0.998 Cr _0.002 TaO ₄ When M ¹ When selected from the combination of Ga and Sc, m=0.02, the chemical formula is Ga _0.6 Sc _0.38 Cr _0.02 TaO ₄ 。

2. A method for preparing the near infrared broad spectrum fluorescent material of claim 1, comprising the steps of:

will contain M ¹ Compounds, containing M ² Grinding the compound and Cr-containing compound, mixing, and sintering at 1450 deg.C or 1400 deg.C in air to obtain near infrared broad spectrum fluorescent material with molecular formula (M) ¹ _1-m Cr _m )M ² O ₄ 。

3. The method according to claim 2, wherein the sintering is performed for a period of 10 to 12 hours.

4. The method of claim 2, wherein the M-containing component comprises ¹ The compound is one or more than two of gallium oxide, gallium nitrate, scandium oxide and scandium nitrate; the M contains ² The compound is tantalum oxide; the Cr compound is chromium oxide or chromium nitrate.

5. The method of manufacturing according to claim 2, wherein after sintering, further comprising: crushing and grinding the sintered product.

6. The use of the near infrared broad spectrum fluorescent material of claim 1 in broad spectrum near infrared LED devices.

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