Phosphate near-infrared two-region fluorescent material as well as preparation method and application thereof

Abstract

The invention discloses a phosphate near-infrared two-region fluorescent material as well as a preparation method and application thereof. The chemical formula of the phosphate near-infrared two-region fluorescent material is Ba10 (P1-xO4) 6O: xMn < 5 + >, Mn < 5 + > is an activating agent, and x is equal to 0.005-0.02. The preparation method of the fluorescent material is a high-temperature solid-phase method and comprises the following steps: weighing a Ba source, a P source and a Mn source according to a stoichiometric ratio, uniformly mixing the raw materials, sintering at a high temperature in an air atmosphere, naturally cooling to room temperature to obtain a sintered product, and grinding the sintered product to obtain the phosphate near-infrared two-region fluorescent material. The fluorescent material disclosed by the invention can be effectively excited by a commercial red light LED chip, forms narrow-band emission in a near-infrared second region, and can be used for temperature detection.

Description

Technical Field

[0001] The present invention relates to the technical field of near-infrared fluorescent materials, and specifically relates to a phosphate near-infrared second-region fluorescent material, a preparation method thereof, and an application thereof. Background Art

[0002] Near-infrared light is invisible light with a wavelength range between 750 - 2500 nm, located between visible light and mid-infrared light, and is part of the electromagnetic spectrum. In the near-infrared region, there are two biological transparent windows, near-infrared region I (NIR-I, 750 - 1000 nm) and near-infrared region II (NIR-II, 1000 - 1700 nm). The second near-infrared window can penetrate a depth of 3 - 5 cm. Therefore, compared with visible light and the first near-infrared window, NIR-II light sources have the advantages of being invisible to the naked eye, having a higher penetration depth, high spatial resolution, less tissue scattering and absorption, and a large imaging depth, and can be widely used in fields such as night vision, anti-counterfeiting, and biomedical imaging. Compared with broad emission peaks, narrow-band emission can reduce signals in applications, suppress noise more thoroughly, have a stronger anti-interference ability, are not easily absorbed by water molecules or organic groups, and can achieve non-overlapping measurements of multiple spectra. Therefore, developing new narrow-band and stable near-infrared second-region fluorescent powders is of great significance.

[0003] Transition metal Mn 5+ The ion transition mode is 3d-3d transition, and its 1 E→ 3 A 2 transition is spin-allowed, and the main characteristics are that the full width at half maximum of the emission spectrum is relatively narrow, and it has a higher absorption cross-section value compared with rare earth ions. The absorption rate is usually greater than 50%, which makes it brighter as a whole and more suitable for imaging / thermometry applications. And the higher absorption cross-section value makes its excitation spectrum cover from visible to near-infrared region I and can match well with LEDs. However, Mn is 5+ an unusual valence state, and the doped matrix material must provide the 5+ stability of the Mn valence state, which 2+ and 4+ Mn valence states have more restrictions on the structure and composition of the material. Therefore, finding a suitable 5+ matrix to minimize the presence of other valence state manganese ions, improve the 5+ stability of Mn, achieve narrow-band emission and high-intensity emission in the near-infrared second region, and promote the 5+ application of Mn in imaging and thermometry is of great significance. Summary of the Invention

[0004] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to overcome the 5+ metastable characteristics of Mn and provide a preparation method with simple conditions and Mn5+ Stable phosphate near-infrared second-zone fluorescent material and its preparation method and application.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A phosphate near-infrared second zone fluorescent material, the chemical formula is Ba 10 (P 1-x O 4 ) 6 O:xMn 5+ , where Mn 5+ is an activator, x = 0.005 to 0.02. x is Mn 5+ With Mn 5+ +P molar ratio.

[0007] Preferably, x=0.01.

[0008] The Mn of the present invention 5+ Doped phosphate near-infrared second-zone fluorescent material, based on Ba 10 (PO 4 ) 6 O as the matrix, Mn 5+ As an activator, the chemical composition is Ba 10 (PO 4 ) 6 O:Mn 5+ ,Mn 5+ Partially replace P 5+ , Mn 5+ The molar doping concentration is 0.5%-2%. The fluorescent material can be excited by ultraviolet-visible light in the range of 250-480nm and visible-near infrared light in the range of 480-900nm, and emits near-infrared light in the range of 1100-1400nm; and the change amplitudes of 1192 and 1245nm wavelengths are different when the temperature is increased, and the fluorescence intensity ratio shows a specific response to temperature changes.

[0009] The preparation method of the above-mentioned phosphate near-infrared second-zone fluorescent material is a high-temperature solid-phase method;

[0010] Preferably, the method for preparing the phosphate near-infrared second zone fluorescent material comprises the following steps:

[0011] Ba source, P source and Mn source are weighed according to the stoichiometric ratio, the raw materials are evenly mixed, and then sintered at high temperature in an air atmosphere. The sintered product is naturally cooled to room temperature to obtain a phosphate near-infrared second zone fluorescent material.

[0012] Further preferably, the Ba source is BaCO 3 , P source is NH 4 H 2 PO4 , the Mn source is MnCO 3 ;

[0013] Further preferably, the molar ratio of P to Mn in the P source and the Mn source is 0.005 - 0.02:0.98 - 0.995;

[0014] Further preferably, the molar ratio of Ba to P+Mn in the Ba source, the P source and the Mn source is 10:6;

[0015] Further preferably, the conditions for the high-temperature sintering are: temperature 1200 - 1300 °C, sintering time 2 - 8 h, and the number of sintering times is 1 time.

[0016] More preferably, the conditions for the high-temperature sintering are: temperature 1200 °C, sintering time 5 h.

[0017] Application of the above-mentioned phosphate near-infrared second-region fluorescent material in preparing a narrow-band near-infrared fluorescence conversion type LED device or preparing a temperature sensor.

[0018] A method for detecting temperature, comprising the following steps:

[0019] Detect the fluorescence spectrum of the phosphate near-infrared second-region fluorescent material in the environment to be measured, calculate the intensity ratio of the emission peak to the vibration peak, and obtain the temperature of the environment to be measured.

[0020] Preferably, the emission peak is 1192 nm and the vibration peak is 1245 nm.

[0021] Application of the above-mentioned phosphate near-infrared second-region fluorescent material in preparing a flexible fluorescent optical fiber temperature sensor.

[0022] A flexible fluorescent optical fiber material, comprising a core, an inner cladding and an outer cladding. The core contains a quartz optical fiber. The refractive index of the outer cladding is less than that of the inner cladding (since it is inaccurate to directly measure the refractive index of the inner cladding containing the phosphate near-infrared second-region fluorescent material, the refractive index of the matrix is used as the refractive index of the inner cladding) and the core, and the inner cladding contains the above-mentioned phosphate near-infrared second-region fluorescent material.

[0023] Preferably, the refractive index of the inner cladding is less than or equal to that of the core.

[0024] Preferably, the core is polymethylphenylsiloxane and a quartz optical fiber; the refractive index of polymethylphenylsiloxane is 1.514;

[0025] Preferably, the inner cladding is a phosphate near-infrared second-region fluorescent material and polymethylphenylsiloxane;

[0026] Preferably, the outer cladding is polydimethylsiloxane; the refractive index of polydimethylsiloxane is 1.404.

[0027] The preparation method of the above flexible fluorescent optical fiber material comprises the following steps:

[0028] (1) Suck the precursor solution of the core into a polytetrafluoroethylene tube with a syringe. Select a polytetrafluoroethylene tube with an appropriate inner diameter according to the required diameter, then insert a quartz optical fiber. After heating and curing, peel off the polytetrafluoroethylene tube to obtain the core;

[0029] (2) Immerse the core in the precursor solution of the inner cladding, take it out and spin it, and heat and cure to obtain the inner cladding;

[0030] (3) Immerse the core coated with the inner cladding in step (2) in the precursor solution of the outer cladding, take it out and spin it, and heat and cure to obtain the outer cladding, that is, obtain the flexible fluorescent optical fiber material.

[0031] Preferably, the precursor solution of the core in step (1) is polymethylphenylsiloxane.

[0032] Preferably, the temperature of heating and curing in step (1) is 90-100 °C, and the time of heating and curing is 1-2 hours;

[0033] Preferably, the precursor solution of the inner cladding in step (2) is a phosphate near-infrared second-region fluorescent material and polymethylphenylsiloxane.

[0034] More preferably, the dosage ratio of the phosphate near-infrared second-region fluorescent material and polymethylphenylsiloxane in step (2) is 0.1-1.0 g: 0.5-1.5 mL.

[0035] Preferably, the temperature of heating and curing in step (2) is 90-100 °C, and the time of heating and curing is 0.5-1 hour;

[0036] Preferably, the precursor solution of the outer cladding in step (3) is polydimethylsiloxane.

[0037] Preferably, the temperature of heating and curing in step (3) is 90-100 °C, and the time of heating and curing is 0.5-1 hour.

[0038] Compared with the prior art, the present invention has the following advantages and effects:

[0039] (1) In the present invention, the matrix material Ba 10 (PO 4 ) 6 O of the phosphate near-infrared second-region fluorescent material does not contain precious metal elements such as rare earth, Ti or Ge, the raw materials are cheap and easy to obtain, the cost is low, and it is easy to carry out large-scale industrial production.

[0040] (2) The preparation of the phosphate near-infrared second-region fluorescent material of the present invention is simple, does not require an oxygen atmosphere, and can be obtained by calcination in air to obtain Mn 5+ , and has good physical, chemical, and thermal stabilities.

[0041] (3) Compared with the reported Mn 5+ -doped near-infrared second-region fluorescent materials, the phosphate near-infrared second-region fluorescent material of the present invention has a specific response to temperature changes and has a new application prospect of being prepared into a flexible optical fiber sensor for temperature measurement. Description of the Drawings

[0042] Figure 1 XRD powder diffraction pattern of the phosphate near-infrared second-region fluorescent material Ba 10 (PO 4 ) 6 O:0.01Mn 5+ prepared in Example 2 and the standard card pattern in the PDF card library.

[0043] Figure 2 Room temperature excitation spectrum and emission spectrum of the phosphate near-infrared second-region fluorescent material Ba 10 (PO 4 ) 6 O:0.01Mn 5+ prepared in Example 2.

[0044] Figure 3 Variable temperature spectrum of the phosphate near-infrared second-region fluorescent material Ba 10 (PO 4 ) 6 O:0.01Mn 5+ prepared in Example 2.

[0045] Figure 4 Fitting curve of the ratio of fluorescence intensity of the emission peak to the vibration peak of the phosphate near-infrared second-region fluorescent material Ba 10 (PO 4 ) 6 O:0.01Mn 5+ prepared in Example 2 varying with temperature.

[0046] Figure 5 Temperature sensitivity curve of the phosphate near-infrared second-region fluorescent material Ba 10 (PO 4 ) 6 O:0.01Mn 5+ prepared in Example 2.

[0047] Figure 6 Emission spectra of the phosphate near-infrared second-region fluorescent materials prepared in Examples 1-4.

[0048] Figure 7 It is a physical picture of the flexible fluorescent optical fiber material prepared in Example 5. Specific Embodiments

[0049] The technical solution of the present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. However, the following embodiments are only for strengthening the description of the technical solution of the present invention, and should not be construed as any limitation to the claimed scope. And the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

[0050] Mn of the present invention 5+ The preparation method of the doped phosphate near-infrared second-region fluorescent material adopts the high-temperature solid-phase method, and includes the following steps:

[0051] Weigh a certain amount of BaCO 3 , NH 4 H 2 PO 4 and MnCO 3 according to the stoichiometric ratio, mix the raw materials evenly and grind them thoroughly for 30 minutes to obtain the raw material powder; put the raw material powder in a corundum crucible and sinter it in an air atmosphere at 1200 °C for 5 hours, and naturally cool it to room temperature to obtain the sintered product, and grind it to obtain the Mn 5+ -doped phosphate near-infrared second-region fluorescent material.

[0052] Example 1

[0053] The preparation of a kind of Mn 5+ -doped phosphate near-infrared second-region fluorescent material (Ba 10 (PO 4 ) 6 O: 0.005Mn 5+ )

[0054] Accurately weigh 10 mmol BaCO 3 , 5.97 mmol NH 4 H 2 PO 4 and 0.03 mmol MnCO 3 , mix the raw materials evenly and grind them thoroughly for 30 minutes to obtain the raw material powder; put the raw material powder in a corundum crucible and sinter it in an air atmosphere at 1200 °C for 5 hours, and naturally cool it to room temperature to obtain the sintered product, and grind it to obtain the phosphate near-infrared second-region fluorescent material.

[0055] The absorption spectrum, excitation spectrum, and emission spectrum of this example are similar to those of Figure 2 This fluorescent material can be excited by ultraviolet-visible light in the range of 250 - 480 nm and visible-near-infrared light in the range of 480 - 900 nm, and emits near-infrared light in the range of 1100 - 1400 nm.

[0056] Example 2

[0057] A Mn 5+ -doped phosphate near-infrared second-region fluorescent material (Ba 10 (PO 4 ) 6 O: 0.01Mn 5+ ) was prepared as follows:

[0058] Accurately weigh 10 mmol of BaCO 3 , 5.94 mmol of NH 4 H 2 PO 4 , and 0.06 mmol of MnCO 3 . Mix the raw materials evenly and grind them thoroughly for 30 minutes to obtain raw material powder; place the raw material powder in a corundum crucible and sinter it in an air atmosphere at 1200 °C for 5 hours, and then cool it naturally to room temperature to obtain a sintered product. Grind it to obtain the borophosphate near-infrared second-region fluorescent material.

[0059] Figure 1 The XRD powder diffraction pattern of the Ba 10 (PO 4 ) 6 O: 0.01Mn 5+ fluorescent material prepared for this example corresponds one-to-one with the spectrum calculated from the cif file of Ba 10 (PO 4 ) 6 O, and no diffraction peak signals of any impurity phases are observed, indicating that the synthesized Ba Figure 1 (PO 10 ) 4 ) 6 O: 0.01Mn 5+ fluorescent material is a pure phase.

[0060] Figure 2 The Ba 10 (PO 4 ) 6 O: 0.01Mn 5+The excitation emission spectrum of the fluorescent material can be excited by ultraviolet-visible light in the range of 250-480nm and visible-near infrared light in the range of 480-900nm, and emits near infrared light in the range of 1100-1400nm. The half-peak width of its excitation spectrum is about 10nm, and the absorption efficiency of the maximum absorption peak of 1192nm is about 61.4%.

[0061] Figure 3 The Ba prepared in this example 10 (PO 4 ) 6 O:0.01Mn 5+ The near-infrared luminescent material has a variable temperature spectrum and has good thermal stability, maintaining 77% of the initial emission intensity (30°C) at 100°C and 61% of the initial emission intensity (30°C) at 150°C.

[0062] Figure 4 The Ba prepared in this example 10 (PO 4 ) 6 O:0.01Mn 5+ A graph showing the relationship between the intensity ratio of the emission peak (1192nm) and the vibration peak (1245nm) of the fluorescent material and temperature, where the FIR is fitted by a linear function, y=0.096+0.0007x, y is the intensity ratio of the emission peak (1192nm) and the vibration peak (1245nm), and x is the temperature (K).

[0063] Figure 5 The Ba prepared in this example 10 (PO 4 ) 6 O:0.01Mn 5+ Temperature sensitivity curve of fluorescent materials, SR is relative sensitivity, according to Figure 5 It can be seen that the highest relative sensitivity reaches 0.322% K at 303 K. -1 .

[0064] Example 3

[0065] A Mn 5+ Doped phosphate near-infrared second-zone fluorescent material (Ba 10 (PO 4 ) 6 O:0.015Mn 5+ ) preparation:

[0066] Accurately weigh 10 mmol BaCO 3 , 5.91mmol NH 4 H 2 PO 4and 0.09 mmol MnCO 3 , mix the raw materials evenly and grind them thoroughly for 30 minutes to obtain a raw material powder; place the raw material powder in a corundum crucible and sinter it in an air atmosphere at 1200 °C for 5 hours, then naturally cool it to room temperature to obtain a sintered product, and grind it to obtain a phosphate near-infrared second-region fluorescent material.

[0067] The absorption spectrum, excitation spectrum and emission spectrum of this example are similar to Figure 2 those, and this fluorescent material can be excited by ultraviolet-visible light in the range of 250 - 480 nm and visible-near-infrared light in the range of 480 - 900 nm, and emit near-infrared light in the range of 1100 - 1400 nm.

[0068] Example 4

[0069] A Mn 5 +-doped phosphate near-infrared second-region fluorescent material (Ba 10 (PO 4 ) 6 O: 0.02Mn 5+ ) preparation:

[0070] Accurately weigh 10 mmol BaCO 3 , 5.88 mmol NH 4 H 2 PO 4 and 0.12 mmol MnCO 3 , mix the raw materials evenly and grind them thoroughly for 30 minutes to obtain a raw material powder; place the raw material powder in a corundum crucible and sinter it in an air atmosphere at 1200 °C for 5 hours, then naturally cool it to room temperature to obtain a sintered product, and grind it to obtain a borophosphate near-infrared second-region fluorescent material.

[0071] The absorption spectrum, excitation spectrum and emission spectrum of this example are similar to Figure 2 those, and this fluorescent material can be excited by ultraviolet-visible light in the range of 250 - 480 nm and visible-near-infrared light in the range of 480 - 900 nm, and emit near-infrared light in the range of 1100 - 1400 nm.

[0072] The emission spectra of the phosphate near-infrared second-region fluorescent materials prepared in Examples 1 - 4 are as shown in Figure 7 , it can be seen that as the doping amount of Mn 5+ increases, the fluorescence intensity first increases and then decreases, and the fluorescence intensity is the largest when the doping amount of Mn 5+ is 0.01 (Example 2).

[0073] Example 5

[0074] A flexible fluorescent optical fiber material capable of temperature sensing, comprising a quartz optical fiber, polydimethylsiloxane, polymethylphenylsiloxane, and a near-infrared fluorescent material.

[0075] The preparation method includes the following steps:

[0076] Take polymethylphenylsiloxane as the precursor solution of the core, and then suck it into a polytetrafluoroethylene tube with a syringe. Select a polytetrafluoroethylene tube with an appropriate inner diameter according to the required diameter, then insert two quartz optical fibers. After heat curing in an oven at 100 °C for 1 h, peel off the polytetrafluoroethylene tube to obtain a transparent core. The inner cladding is prepared by the spin coating method. Uniformly mix 1 g of polymethylphenylsiloxane and 0.1 g of near-infrared fluorescent powder as the precursor solution of the inner cladding, mechanically stir for 30 min, then immerse the core in the precursor solution of the inner cladding, dip up a small amount of the solution, and place the core on a rotating motor to spin and form a uniform coating layer. Heat cure in an oven at 90 °C for 40 min; 1 g of polydimethylsiloxane is used as the precursor solution of the outer cladding, and the outer cladding is prepared by the same method. The size of the cladding is controlled by the speed and time of the motor. The refractive index of the outer cladding is less than that of the core and the inner cladding, which can better confine light to transmit in the core and the inner cladding and improve the excitation and collection efficiency of fluorescence; through the above three-step operation, a flexible fluorescent optical fiber material with a double-cladding structure as expected is finally obtained. Among them, the near-infrared fluorescent powder is the near-infrared fluorescent powder of the above Example 2, and its chemical composition formula is Ba 10 (PO 4 ) 6 O:0.01Mn 5+ .

[0077] Figure 7 is a physical diagram of the prepared flexible fluorescent optical fiber material.

[0078] It should be understood that any modifications, substitutions, or changes made by those skilled in the art based on the true spirit of the present invention on the basis of the specific embodiments of the present invention should be covered by the protection scope of the present invention.

Claims

1. A phosphate near-infrared second zone fluorescent material, characterized in that: The chemical formula is Ba 10 (P 1-x O4)6O:xMn 5+ , where Mn 5+ is an activator, x=0.005~0.

02.

2. The phosphate near-infrared second zone fluorescent material according to claim 1, characterized in that: x＝0.01。 3. The method for preparing the phosphate near-infrared second-zone fluorescent material according to any one of claims 1 to 2, characterized in that: The preparation method is a high temperature solid phase method; comprising the following steps: Ba source, P source and Mn source are weighed according to the stoichiometric ratio, the raw materials are evenly mixed, and then sintered at high temperature in an air atmosphere. The sintered product is naturally cooled to room temperature to obtain a phosphate near-infrared second zone fluorescent material.

4. The preparation method according to claim 3, characterized in that: The Ba source is BaCO3, the P source is NH4H2PO4, and the Mn source is MnCO3; The molar ratio of P to Mn in the P source and the Mn source is 0.005-0.02:0.98-0.995; The molar ratio of Ba to P+Mn in the Ba source, P source and Mn source is 10:6; The high temperature sintering conditions are: temperature 1200-1300° C., sintering time 2-8 hours, and sintering number 1 time.

5. Use of the phosphate near-infrared second-zone fluorescent material according to any one of claims 1 to 2 in preparing a narrow-band near-infrared fluorescence conversion LED device or a temperature sensor.

6. A method for detecting temperature, characterized in that: The following steps are involved: The fluorescence spectrum of the phosphate near-infrared second zone fluorescent material in the test environment is detected, and the intensity ratio of the emission peak to the vibration peak is calculated to obtain the temperature of the test environment.

7. A flexible fluorescent optical fiber material, characterized in that: The fiber core comprises a quartz optical fiber, the refractive index of the outer cladding is smaller than that of the inner cladding and the fiber core, and the inner cladding comprises the phosphate near-infrared second zone fluorescent material as claimed in any one of claims 1 to 2.

8. The flexible fluorescent optical fiber material according to claim 7, characterized in that: The fiber core is polymethylphenylsiloxane and quartz optical fiber; The inner cladding is a phosphate near-infrared second-zone fluorescent material and polymethylphenylsiloxane; The outer layer is polydimethylsiloxane.

9. The method for preparing the flexible fluorescent optical fiber material according to any one of claims 7 to 8, characterized in that: The following steps are involved: (1) The precursor solution of the fiber core is sucked into a polytetrafluoroethylene tube with a syringe, a polytetrafluoroethylene tube with an appropriate inner diameter is selected according to the required diameter, and then a quartz optical fiber is inserted. After heating and curing, the polytetrafluoroethylene tube is peeled off to obtain the fiber core; (2) immersing the fiber core in the precursor solution of the inner cladding, taking it out, spinning it, and heating and curing it to obtain the inner cladding; (3) immersing the fiber core coated with the inner cladding in step (2) in the precursor solution of the outer cladding, taking it out and spinning it, and heating and curing it to obtain the outer cladding, thereby obtaining a flexible fluorescent optical fiber material.

10. The method for preparing the flexible fluorescent optical fiber material according to claim 9, characterized in that: The temperature of the heating and curing in step (1) is 90 to 100 degrees Celsius, and the heating and curing time is 1 to 2 hours; The precursor solution of the inner cladding in step (2) is a phosphate near-infrared second zone fluorescent material and polymethylphenylsiloxane; the amount ratio of the phosphate near-infrared second zone fluorescent material to the polymethylphenylsiloxane is 0.1-1.0 g: 0.5-1.5 mL; The temperature of the heating and curing in step (2) is 90 to 100 degrees Celsius, and the heating and curing time is 0.5 to 1 hour; The temperature of the heating and curing in step (3) is 90 to 100 degrees Celsius, and the time of the heating and curing is 0.5 to 1 hour.

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