A blue light excited broadband near-infrared sulfide luminescent material and a preparation method thereof

Abstract

The present invention is applicable to the technical field of fluorescent materials and provides a broadband near-infrared sulfide luminescent material excited by blue light. The chemical formula of the luminescent material is SrSc 2‑2x Cr x S4, wherein 0.0025≤x≤0.015. The present invention also provides a method for preparing a broadband near-infrared sulfide luminescent material excited by blue light. The present invention also provides an application of a broadband near-infrared sulfide luminescent material excited by blue light. 3+ Cr 3+ Ion substitution, with Cr 3+ Ion substitution of Sc 3+ The emission intensity of the ions changes accordingly and can be effectively excited by blue light. The optimal emission wavelength is at 1030nm, which is derived from Cr 3+ of 4 T2→ 4 The electronic transition of A2 produces high-efficiency near-infrared broadband emission with a half-width of 225nm under 468nm blue light excitation; the raw material resources used are abundant, the preparation method is simple and easy, the physicochemical stability is good, the fluorescence lifetime is ideal, it is green and pollution-free, and it has strong applicability. In addition, the emission bandwidth and emission wavelength are long, and it can be widely used in the field of near-infrared spectroscopy technology.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluorescent materials, and particularly relates to a blue light excited broadband near-infrared sulfide luminescent material and a preparation method. BACKGROUND

[0002] Near-infrared light has the advantages of low energy and strong penetration ability, and near-infrared spectroscopy has the characteristics of fast detection, non-destructive, real-time and the like, and has attracted more and more attention. Among them, the wide spectrum of near-infrared light at 650-1050 nm covers the frequency doubling and frequency mixing characteristic information of hydrogen-containing groups (O-H, N-H, C-H) vibration. By scanning the near-infrared wide spectrum of the sample, the characteristic information of the hydrogen-containing groups of the organic molecules in the sample can be obtained, which can be widely used in food detection, environmental pollution detection and the like. The wide spectrum or multi-spectrum at 850-1200 nm and 1400-1800 nm can be applied to medical detection, biological identification and security monitoring fields. Therefore, near-infrared light has a great application prospect in the fields of detection and analysis, biological imaging, night vision lighting, modern agriculture, machine vision and the like.

[0003] The commonly used near-infrared light sources on the market mainly include incandescent lamps, halogen lamps, fluorescent lamps, short-wave infrared lasers and infrared light-emitting diodes, which all have inherent defects. The incandescent lamps and halogen lamps have the disadvantages of large size, high energy consumption, low efficiency and short service life; the fluorescent lamps have the disadvantages of low efficiency, containing heavy metal elements and being prone to flicker; the short-wave infrared laser has the disadvantages of small divergence angle, high power consumption and relatively high cost; the infrared light-emitting diode has the disadvantages of narrow emission band, poor thermal stability and high production equipment cost, and cannot be widely applied to the field of near-infrared spectroscopy technology. In recent years, due to the invention of blue light chip InGaN, the research on near-infrared fluorescent conversion type light-emitting diodes (NIR pc-LEDs) has developed rapidly. By combining a blue light LED chip with a near-infrared fluorescent powder with excellent performance, the obtained near-infrared light-emitting diode has the advantages of low cost, adjustable spectrum, long service life, high luminous efficiency, high thermal stability, small size, rapid response and the like, and gradually becomes the mainstream light source of near-infrared.

[0004] In the NIR pc-LEDs technology, the near-infrared luminescent fluorescent powder as a key component plays a crucial role in determining the overall optical performance. However, the existing near-infrared emission systems mainly emit in the wavelength less than 1000 nm, and still lack long-wave emission near-infrared fluorescent powder systems. In addition, some existing near-infrared fluorescent powders also have the disadvantages of low luminescent quantum efficiency and poor thermal stability, which limits their application in some fields.

[0005] Therefore, it is urgent to develop a near-infrared luminescent material which is excited by blue light and has the advantages of long emission wavelength, wide emission band, high luminous intensity and good stability. SUMMARY

[0006] The embodiment of the present application aims to provide a blue light excited broadband near-infrared sulfide luminescent material, and aims to solve the problems in the background art.

[0007] The embodiment of the present application is implemented as follows: a blue light excited broadband near-infrared sulfide luminescent material, the chemical general formula of the luminescent material is SrSc 2-2x Cr x S4, wherein 0.0025≤x≤0.015.

[0008] Another purpose of the embodiment of the present application is to provide a preparation method of a blue light excited broadband near-infrared sulfide luminescent material, comprising the following steps:

[0009] According to the chemical general formula SrSc 2-2x Cr x S4, the raw materials are weighed according to the molar ratio of Sr:Sc:Cr in the raw materials, wherein 0.0025≤x≤0.015, and the raw materials are compounds containing Sr, Sc and Cr elements.

[0010] The weighed raw materials are added to a dispersant and ground sufficiently, and the ground powder is obtained by volatilizing the dispersant, the ground powder is pre-fired at 750-850 DEG C for 2-3h, then sulfurization gas is introduced, and the powder is fired at 950-1100 DEG C for 2-4h, and then slowly reduced to room temperature until cooled, thereby obtaining the blue light excited broadband near-infrared sulfide luminescent material.

[0011] Preferably, the compound containing Sr element is one of SrO, SrCO3, Sr(OH)2, SrCl2 and SrSO4.

[0012] Preferably, the compound of Sc element is one of Sc2O3, Sc(OH)3, Sc2(CO3)3 and Sc2S3.

[0013] Preferably, the compound containing Cr element is one of Cr2O3, CrCl3 and Cr2(CO3)3.

[0014] Preferably, the dispersant is anhydrous ethanol.

[0015] Another purpose of the embodiment of the present application is to provide an application of the blue light excited broadband near-infrared sulfide luminescent material in the field of nondestructive testing, food and agricultural product testing, biomedicine and environmental pollution testing.

[0016] The embodiment of the present application provides a blue light excited broadband near-infrared sulfide luminescent material, the chemical general formula of which is SrSc 2-2x Cr xS4, Sc in the formula 3+ ions are replaced by Cr 3+ ions are replaced by Cr 3+ ions are replaced by Cr 3+ ions are replaced by Cr 3+ ions are replaced by Cr 4 T2→ 4 A2, and a high-efficiency near-infrared broadband emission with a half-peak width of 225 nm is generated under blue light excitation at 468 nm.

[0017] The preparation method provided by the embodiments of the present application has the advantages of rich reserves of raw material resources, simple and easy-to-operate preparation method, good physicochemical stability, ideal fluorescence lifetime, green and pollution-free, strong applicability, wide emission bandwidth and wavelength, and wide application in the field of near-infrared spectroscopy. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 XRD patterns of samples prepared in Examples 1-6 and Comparative Example 1 of the present application;

[0019] Figure 2 Excitation spectra of samples prepared in Examples 1-6 of the present application;

[0020] Figure 3 Emission spectra of samples prepared in Examples 1-6 of the present application under excitation at 468 nm;

[0021] Figure 4 Emission spectra of samples prepared in Example 3 of the present application under excitation at 468 nm;

[0022] Figure 5 Variable-temperature emission spectra of samples prepared in Example 3 of the present application under excitation at 468 nm;

[0023] Figure 6 Variable-temperature intensity normalized spectra of samples prepared in Example 3 of the present application under excitation at 468 nm;

[0024] Figure 7 Emission spectra of pc-LED devices packaged by using samples prepared in Example 3 of the present application and blue LED chips under different currents. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0026] A blue light excited broadband near-infrared sulfide luminescent material, and a preparation method thereof, the preparation method comprising the following steps:

[0027] (1) according to the chemical formula SrSc 2-2x Cr x S4, the corresponding raw materials are accurately weighed by an electronic balance according to the molar ratio of Sr:Sc:Cr=1:2-2x:x, x is 0.0025≤x≤0.015 respectively, wherein the raw materials are Sr source, Sc source and Cr source respectively;

[0028] The Sr source is an oxide containing Sr or a compound capable of being converted into the oxide;

[0029] The Sc source is an oxide containing Sc or a compound capable of being converted into the oxide;

[0030] The Cr source is an oxide containing Cr or a compound capable of being converted into the oxide;

[0031] (2) the weighed raw materials are put into an agate mortar, anhydrous ethanol is added as a dispersant for grinding, and the grinding is performed until the alcohol is volatilized to obtain a uniform powder, the ground powder is put into an alumina crucible, the crucible is placed in a tube furnace at 750-850 DEG C for pre-sintering for 2-3h, then the crucible is moved into a tube furnace at 950-1100 DEG C and sulfurization gas CS2 is introduced, and the sintering is performed for 2-4h in a sulfurization environment, and then slowly reduced to room temperature until cooling, so that the high-efficiency near-infrared luminescent material is obtained.

[0032] The specific implementation of the present application is described in detail in combination with specific examples.

[0033] Example 1, a blue light excited broadband near-infrared sulfide luminescent material, and a preparation method thereof, the preparation method comprising the following steps:

[0034] (1) according to the chemical formula SrSc 2-2x Cr x S4 (x=0.0025) composition, the initial raw materials are selected from SrCO3, Sc2O3 and Cr2O3, and the raw materials are accurately weighed according to the molar ratio of each element, and an appropriate amount of anhydrous ethanol is added as a dispersant for grinding for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0035] (2) the mixed powder is put into an alumina crucible, the crucible is placed in a tube furnace at 900 DEG C for pre-sintering for 2h, then the crucible is moved to a tube furnace at 1100 DEG C and sulfurization gas CS2 is introduced for sintering for 3h, and then slowly reduced to room temperature until cooling.

[0036] Example 2, a blue light excited broadband near-infrared sulfide luminescent material, and a preparation method thereof, the preparation method comprising the following steps:

[0037] (1) A blue light excited broadband near-infrared sulfide luminescent material with a chemical formula of SrSc 2-2x Cr x S4 (x=0.005) is prepared by the following steps: (1) raw materials of SrCO3, Sc2O3, and Cr2O3 are weighed according to the molar ratio of each element, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0038] (2) the mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurization gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0039] Example 3, a blue light excited broadband near-infrared sulfide luminescent material, is prepared by the following steps:

[0040] (1) A blue light excited broadband near-infrared sulfide luminescent material with a chemical formula of SrSc 2-2x Cr x S4 (x=0.0075) is prepared by the following steps: (1) raw materials of SrCO3, Sc2O3, and Cr2O3 are weighed according to the molar ratio of each element, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0041] (2) the mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurization gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0042] Example 4, a blue light excited broadband near-infrared sulfide luminescent material, is prepared by the following steps:

[0043] (1) A blue light excited broadband near-infrared sulfide luminescent material with a chemical formula of SrSc 2-2x Cr x S4 (x=0.01) is prepared by the following steps: (1) raw materials of SrCO3, Sc2O3, and Cr2O3 are weighed according to the molar ratio of each element, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0044] (2) the mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurization gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0045] Example 5, a blue light excited broadband near-infrared sulfide luminescent material, is prepared by the following steps:

[0046] (1) A blue light excited broadband near-infrared sulfide luminescent material with a chemical formula of SrSc2-2x Cr x S4 (x=0.0125) composition, the initial raw material is selected from SrCO3, Sc2O3, Cr2O3, and each element is accurately weighed according to the molar ratio, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0047] (2) The mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurizing gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0048] Example 6, a near-infrared luminescent material, the preparation method comprising the following steps:

[0049] (1) According to the chemical formula SrSc 2-2x Cr x S4 (x=0.015) composition, the initial raw material is selected from SrCO3, Sc2O3, Cr2O3, and each element is accurately weighed according to the molar ratio, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0050] (2) The mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurizing gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0051] Comparative Example 1, a high-efficiency near-infrared luminescent material, the preparation method comprising the following steps:

[0052] (1) According to the chemical formula SrSc 2-2x Cr x S4 (x=0) composition, the initial raw material is selected from SrCO3, Sc2O3, and each element is accurately weighed according to the molar ratio, and a proper amount of anhydrous ethanol is added as a dispersant to fully grind for 30 min, so that the raw materials are uniformly mixed to obtain a mixed powder;

[0053] (2) The mixed powder is placed in an alumina crucible, the crucible is placed in a tube furnace at 900°C for 2h, then the crucible is moved to a tube furnace at 1100°C and sulfurizing gas CS2 is introduced for 3h, and then slowly cooled to room temperature until cooled.

[0054] Performance test:

[0055] The samples prepared in Examples 1-6 and Comparative Example 1 are analyzed by powder X-ray diffraction (XRD) technology, and the XRD patterns are as follows: Figure 1The standard card mp-17678 is shown; it can be seen that the samples prepared by examples 1-6 and comparative example 1 can all be well matched with the standard card mp-17678, indicating that the prepared fluorescent materials are all pure phases; through spectral testing, the sample prepared by comparative example 1 has no emission signal response under 468nm excitation, indicating that the sample has no near-infrared luminescence; 2-2x Cr x S4 (x=0), i.e. SrSc2S4, has no emission signal response under 468nm excitation, indicating that the sample has no near-infrared luminescence;

[0056] Figure 2 and Figure 3 The emission and excitation spectra of the samples prepared by examples 1-6 are shown; it can be seen that the excitation spectrum of the sample under 1030nm near-infrared monitoring shows a broadband excitation peak in the range of 200 to 750nm, and there is a relatively strong excitation near 468nm, indicating that it can be applied to pc-LED under blue LED chip excitation; under 468nm excitation, the sample shows broadband near-infrared emission, extending from 800nm to about 1600nm, and the main emission peak wavelength is near 1030nm;

[0057] Figure 4 The optimal emission wavelength and half-peak width of the emission spectrum of the sample prepared by example 3 are shown; it can be seen that the sample shows broadband emission in the near-infrared region under 468nm excitation, with a half-peak width of 225nm and an optimal emission wavelength of 1030nm; the emission wavelength almost covers the entire near-infrared region and part of the second region, and can be widely applied in the field of near-infrared spectroscopy technology;

[0058] Figure 5 The variable-temperature luminescence spectrum of the sample prepared by example 3 is shown; it can be seen that the emission intensity of the sample steadily decreases with the increase of temperature due to thermal quenching effect, and the sample shows good thermal stability;

[0059] Figure 6 The variable-temperature intensity normalized spectrum of the sample prepared by example 3 is shown; it can be seen that under 468nm excitation, when the temperature is increased to 423K (150℃), the emission intensity of the sample still maintains about 61.8% of the initial intensity;

[0060] Figure 7 The emission spectra of the LED device prepared by using the sample prepared by example 3 and a commercial blue chip under different current driving are shown, indicating that the fluorescent powder prepared by the example can be successfully prepared into a near-infrared LED device with a commercial blue chip, and the luminous intensity increases with the increase of current, proving that the near-infrared LED device has good luminescent performance.

[0061] To sum up, the material prepared by the embodiment of the application has advantages of wide-band emission and emission wavelength, and has great application potential in the fields of biological identification, non-invasive monitoring, food analysis and environmental detection.

[0062] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A broadband near-infrared sulfide luminescent material excited by blue light, characterized in that: The chemical formula of the luminescent material is SrSc 2-2x Cr x S4, where 0.0025≤x≤0.

015.

2. A method for preparing a blue light-excited broadband near-infrared sulfide luminescent material according to claim 1, characterized in that: The following steps are involved: According to the chemical formula SrSc 2-2x Cr x S4, weighing raw materials according to the molar ratio of each element in the raw materials Sr:Sc:Cr=1:2-2x:x, where 0.0025≤x≤0.015, and the raw materials are compounds containing Sr, Sc, and Cr elements respectively; The weighed raw materials are added to a dispersant and ground thoroughly until the dispersant evaporates to obtain a uniform powder. The ground powder is pre-calcined at 750-850°C for 2-3 hours, and then a sulfiding gas is introduced and fired in a sulfiding environment of 950-1100°C for 2-4 hours. The temperature is then slowly lowered to room temperature until it cools to obtain the blue light-excited broadband near-infrared sulfide luminescent material.

3. The method for preparing a blue light-excited broadband near-infrared sulfide luminescent material according to claim 2, characterized in that: The compound containing the Sr element is one of SrO, SrCO3, Sr(OH)2, SrCl2, and SrSO4.

4. The method for preparing a blue light-excited broadband near-infrared sulfide luminescent material according to claim 2, characterized in that: The compound of the Sc element is one of Sc2O3, Sc(OH)3, Sc2(CO3)3, and Sc2S3.

5. The method for preparing a blue light-excited broadband near-infrared sulfide luminescent material according to claim 2, characterized in that: The compound containing Cr element is one of Cr2O3, CrCl3, and Cr2(CO3)3.

6. The method for preparing a blue light-excited broadband near-infrared sulfide luminescent material according to claim 2, characterized in that: The dispersant is anhydrous ethanol.

7. Application of the blue light-excited broadband near-infrared sulfide luminescent material according to claim 1 in the fields of non-destructive testing, food and agricultural product testing, biomedicine, and environmental pollution detection.

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