Preparation method and application of Cr < 3 + > activated near-infrared fluorescent powder

Abstract

The invention belongs to the field of inorganic luminescent materials, and discloses a preparation method and application of Cr < 3 + > activated near-infrared fluorescent powder. The general chemical formula of the near-infrared fluorescent powder is Gd < 1-y > Y < y > Al < 3-x > (BO3) 4: xCr < 3 + >, wherein the value range of y is from 0.1 to 0.6, and the value range of x is from 0.01 to 0.09. The Cr < 3 + >-doped near-infrared fluorescent powder Gd < 1-y > YyAl < 3-x > (BO3) 4: xCr < 3 + > provided by the invention overcomes the defects of low efficiency, short service life, small spectral continuity and the like of the existing near-infrared light source. The broadband near-infrared emission fluorescent powder with high efficiency and high thermal stability and the near-infrared LED device formed by the broadband near-infrared emission fluorescent powder can meet the application requirements of plant light supplement.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic luminescent materials, and the present invention relates to a Cr 3+ The invention relates to a preparation method and application of activated near-infrared phosphor. 3+ Preparation method of activated near-infrared phosphor and its application in plant supplementary lighting. Background Art

[0002] Near-infrared light sources, due to their deep penetration, non-toxicity, and invisibility, have attracted widespread attention in emerging technologies such as near-infrared spectroscopy, plant lighting, bioimaging, and night vision. However, currently available near-infrared light sources (such as halogen lamps and semiconductor lasers) suffer from low efficiency, short lifespan, and limited spectral continuity, making them difficult to meet the application requirements of these fields.

[0003] Drawing on commercially available phosphor-converted white light LED technology, light-converted near-infrared LEDs, based on a combination of commercial high-power blue LED chips and near-infrared luminescent materials, have become an ideal choice for the next generation of solid-state infrared light sources. In 2016, Osram launched the world's first phosphor-converted near-infrared LED (SFH4735). The development of this chip strengthened Osram's competitive advantage in the agricultural LED market. However, currently commercially available near-infrared LED sources still face bottlenecks such as narrow wavelength coverage, low optical power, and severe thermal quenching of the near-infrared emission. The fundamental reason for this is the lack of near-infrared phosphors that are well-matched with commercial blue LED chips, highly efficient, and thermally stable. High-performance near-infrared luminescent materials, as the core of near-infrared LED devices, have become a key technology for high-quality near-infrared solid-state light sources.

[0004] Cr 3+ Ions occupying a weak crystal field environment can achieve near-infrared emission in the range of 700 to 1200 nm and can be effectively excited by blue LED chips. 3+ Near-infrared LED devices made of doped near-infrared phosphors have shown broad application prospects in the fields of biological imaging, biological detection, food monitoring and plant lighting. However, in the face of the requirements of high efficiency, excellent thermal stability and good device performance of practical high-power LED devices such as plant lighting, the research and development of near-infrared phosphors faces huge challenges. Most Cr 3+ Doped near-infrared phosphors have the disadvantage of being difficult to simultaneously meet the requirements of high power, high electro-optical conversion efficiency, high stability, and resistance to thermal quenching, which limits the practical application of such phosphors.

[0005] Cr 3+ The luminescence properties of Cr are greatly affected by the matrix lattice environment. The matrix material determines the 3+The emission wavelength, emission spectrum bandwidth, and thermal stability of the new Cr 3+ Activated near-infrared phosphors and their synthesis methods, obtaining high-efficiency broadband near-infrared luminescent materials, and breaking through the thermal stability of existing luminescent materials are issues that must be solved to obtain high-efficiency, high-reliability near-infrared LED light sources and meet practical application requirements. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a Cr 3+ The preparation method and application of activated near-infrared phosphors address the shortcomings of existing near-infrared light sources (such as halogen lamps and semiconductor lasers), such as low efficiency, short lifespan, and limited spectral continuity. The method provides a highly efficient, thermally stable broadband near-infrared emitting phosphor and the resulting near-infrared LED device, capable of meeting the needs of plant supplementary lighting applications.

[0007] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0008] A Cr 3+ Activated near-infrared phosphor, the chemical formula of near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ ; Among them, the value range of y is 0.1 to 0.6, and the value range of x is 0.01 to 0.09.

[0009] Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ The near-infrared emission wavelength range is 650~1100nm, among which Cr 3+ It is the near-infrared emission center.

[0010] The present invention also claims the protection of the above Cr 3+ The method for preparing activated near-infrared phosphor comprises the following steps:

[0011] S1. Accurately weigh the raw materials according to the stoichiometric ratio of each element in the chemical formula;

[0012] S2. Place all ingredients in an agate mortar and grind them into a slurry with 4-8 ml of anhydrous ethanol (analytical grade) per gram of raw material. Grind for 15-25 minutes until the anhydrous ethanol evaporates completely, leaving a powdered mixture.

[0013] S3. The mixture was poured into a crucible, placed in a muffle furnace, and calcined at 1000-1300 ℃ for 5-7 hours to obtain a calcined product;

[0014] S4. After cooling to room temperature, the calcined product was removed from the muffle furnace and ground again for 5-15 minutes to obtain the near-infrared phosphor Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ .

[0015] Furthermore, in step S1, the raw materials are Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3.

[0016] Furthermore, in step S2, preferably 5 ml of anhydrous ethanol is added per gram of raw material, and grinding is preferably performed for 20 minutes.

[0017] Furthermore, in step S3, calcination is preferably performed at 1200° C. for 6 hours.

[0018] Furthermore, in step S4, grinding is preferably performed for 10 minutes.

[0019] The present invention also claims the protection of the above Cr 3+ Activated near-infrared phosphor or Cr prepared by the above preparation method 3+ Application of activated near-infrared phosphors in the preparation of near-infrared LEDs.

[0020] Specifically: Cr 3+ The activated near-infrared phosphor is combined with a commercial 450nm blue LED chip to produce a near-infrared LED. The near-infrared LED device emits light in the wavelength range of 650 to 1100nm.

[0021] The present invention also claims the protection of the above Cr 3+ Activated near-infrared phosphor or Cr prepared by the above preparation method 3+ Application of activated near-infrared phosphor in plant lighting. 3+ The activated near-infrared phosphor is compounded with a commercial 450nm blue light LED chip to obtain a near-infrared LED; the near-infrared LED is used as a light source for plant supplementary lighting.

[0022] The present invention introduces Y 3+ Replacement of Gd 3+ Obtain Gd with excellent overall performance 1-y Y y Al 3-x (BO3)4:xCr 3+ Near-infrared phosphor. The optimized luminescence mechanism is attributed to Y 3+ Replacement of Gd 3+ , which helps to improve the luminescence performance and thermal stability, and helps to form a solid solution with better crystallinity and harder crystal structure.

[0023] The beneficial effects of the present invention compared with the prior art are:

[0024] The Cr provided by the present invention 3+ Doped near-infrared phosphor Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ , can be efficiently excited by blue light and convert it into near-infrared light of 650-1100nm, with a peak at 720nm. 3+ Ion doping partially replaces Gd in the material 3+ , which helps to form a solid solution with better crystallinity and harder crystal structure, and significantly inhibits the Cr 3+ The non-radiative relaxation of the emission center improves the luminescence performance and resistance to thermal quenching of the material.

[0025] The near-infrared phosphor provided by the present invention has high luminous brightness, good physical and chemical stability, simple preparation process, and low cost of raw materials used.

[0026] The LED device prepared from the near-infrared phosphor provided by the present invention has low cost, high luminous efficiency and long service life. At a driving current of 100mA, its output power is 40.4mW and its photoelectric conversion efficiency is 14.7%. After 30 days of continuous operation, the electroluminescence intensity of the near-infrared LED device remains at 96.5% of the previous level. The device can meet the application requirements of plant supplementary lighting. The obtained near-infrared LED device was used to carry out a cultivation experiment of butter leaf lettuce. The growth pattern of the plant changed significantly under the irradiation of the near-infrared LED, with dry weight increased by 13%, fresh weight increased by 19%, chlorophyll a increased by 5%, chlorophyll b increased by 25%, plant height increased by 140%, and plant width increased by 64%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 XRD patterns of the near-infrared phosphors prepared in Examples 1-5 of the present invention;

[0028] Figure 2 XRD patterns of the near-infrared phosphors prepared in Examples 3 and 6-11 of the present invention;

[0029] Figure 3 The excitation and emission spectra of the near-infrared phosphor prepared in Example 10 of the present invention;

[0030] Figure 4 The temperature-dependent temperature spectrum of the near-infrared phosphor prepared in Example 3 of the present invention;

[0031] Figure 5 The temperature-dependent temperature spectrum of the near-infrared phosphor prepared in Example 10 of the present invention;

[0032] Figure 6 The near-infrared LED device prepared in Application Example 1 of the present invention and its electroluminescence spectrum characteristic diagram;

[0033] Figure 7 This is the electroluminescence spectrum of the near-infrared LED device prepared in Application Example 1 of the present invention before and after 30 days of operation.

[0034] Figure 8 This is a schematic diagram of the morphology of butter leaf lettuce in CK and NIR in Application Example 1 of the present invention; Figure a is a front comparison diagram, and Figure b is an overall comparison diagram.

[0035] Figure 9 This is a data comparison chart of Application Example 1 of the present invention, wherein Figure a is a fresh weight comparison chart, Figure b is a dry weight comparison chart, Figure c is a chlorophyll comparison chart, Figure d is a chlorophyll b comparison chart, Figure e is a plant height comparison chart, and Figure f is a plant width comparison chart. DETAILED DESCRIPTION

[0036] The present invention is described in detail below by specific examples, but the scope of protection of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0037] Example 1

[0038] GdAl 3-x (BO3)4:xCr 3+ Preparation of (x=0.01)

[0039] Gd2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 1:2.99:0.01:4 for Gd, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The materials were then poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0040] Example 2

[0041] GdAl 3-x (BO3)4:xCr 3+ Preparation of (x=0.03)

[0042] Gd2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 1:2.97:0.03:4 for Gd, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The materials were then poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0043] Example 3

[0044] GdAl 3-x (BO3)4:xCr 3+ Preparation of (x=0.05)

[0045] Gd2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 1:2.95:0.05:4 for Gd, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The materials were then poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0046] Example 4

[0047] GdAl 3-x (BO3)4:xCr 3+ Preparation of (x=0.07)

[0048] Gd2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 1:2.93:0.07:4 for Gd, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The materials were then poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0049] Example 5

[0050] GdAl 3-x (BO3)4:xCr 3+ Preparation of (x=0.09)

[0051] Gd2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 1:2.91:0.09:4 for Gd, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The materials were then poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0052] Figure 1 The XRD diffraction pattern of the near-infrared phosphor prepared in Example 1-5 is shown in Figure 1. No impurity peaks are observed in the figure, indicating that a small amount of Cr 3+ The introduction of ions does not change the crystal structure or generate impurities. 3+ As the doping amount increases, the diffraction peak gradually shifts to a smaller angle, indicating that Cr 3+ The introduction of ions makes the matrix GdAl 3-x (BO3)4 produces a certain degree of distortion.

[0053] Example 6

[0054] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ , where the value of y represents Y 3+ To Gd 3+ Partial replacement of . With x set to 0.05 and y set to 0.1, Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 0.9:0.1:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0055] Example 7

[0056] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+, x is 0.05, and y is 0.2. Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed to a molar ratio of 0.8:0.2:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0057] Example 8

[0058] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ , x is 0.05, and y is 0.3. Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed to a molar ratio of 0.7:0.3:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0059] Example 9

[0060] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ , x is 0.05, and y is 0.4. Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed to a molar ratio of 0.6:0.4:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0061] Example 10

[0062] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+, x is 0.05, and y is 0.5. Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed to a molar ratio of 0.5:0.5:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0063] Example 11

[0064] The chemical formula of the near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ , x is set to 0.05, and y is set to 0.6. Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3 powders were weighed according to a molar ratio of 0.4:0.6:2.95:0.05:4 for Gd, Y, Al, Cr, and B. All ingredients were then ground in an agate mortar for 20 minutes to mix thoroughly. The material was poured into a crucible, placed in a muffle furnace, and calcined at 1200°C for 6 hours. After cooling to room temperature, the sample was removed from the muffle furnace and ground again for 10 minutes to obtain a near-infrared phosphor.

[0065] Figure 2 The XRD diffraction patterns of the near-infrared phosphors prepared in Examples 3 and 6-11 show no impurity peaks, and the diffraction peaks gradually shift to larger angles, indicating that Gd 3+ ions are surrounded by Y 3+ Ion occupancy. Figure 3 The excitation and emission spectra of the near-infrared phosphor prepared in Example 10 show broadband emission in the 650-1100 nm range, consisting of a wide band centered at 720 nm and a sharp line peaking at 687 nm. The excitation spectrum covers the visible light range of 400-700 nm, particularly the wide band between 350-500 nm, which aligns well with the emission range of commercial blue LED chips, allowing for efficient excitation by blue light.

[0066] Figure 4 、 Figure 5 The temperature-dependent spectra of the near-infrared phosphors prepared in Example 3 and Example 10 are shown. Due to thermal quenching, the luminous intensity of the phosphor in Example 3 is 73.8% of that at room temperature (298K) when heated to 423K. 3+ ions, it increased to 92.5% @ 423K. 1-y Yy Al 3-x (BO3)4:xCr 3+ (x=0.05, y=0.5) The thermal stability of photoluminescence is significantly improved, and the near-infrared phosphor prepared in Example 10 has the best effect.

[0067] Application Example 1

[0068] The near-infrared phosphor prepared in Example 10 was encapsulated into a near-infrared LED to study its application in plant lighting. The purpose was to provide a near-infrared light source that promotes plant growth.

[0069] The light source is prepared by packaging the near-infrared phosphor prepared in Example 10 with a commercially available 450nm blue LED chip. The near-infrared phosphor prepared in Example 10 is evenly mixed with transparent glue in a mass ratio of 1:1, and covered on the blue LED chip by dispensing glue. The circuit is welded and packaged to obtain a near-infrared LED device.

[0070] The obtained near-infrared LED device was used as a supplementary light source for the growth test of butter leaf lettuce. The growth observation period was 4 weeks, and the physiological indicators of the plants were compared and tested after 4 weeks.

[0071] Plant cultivation: Uniformly grown butterleaf lettuce seedlings were divided into two groups. One group used a commercial red and blue LED light source (Shenzhen Huazhi Electronics Co., Ltd.) as the control group (CK), and the other group used a composite light source containing commercial red and blue LEDs and the homemade near-infrared LEDs of the present invention as the experimental group (NIR). Light treatment: Both groups of seedlings were grown under the same light intensity and duration, and their growth indicators, such as fresh weight, dry weight, and chlorophyll content, were recorded. The cultivation period was 4 weeks.

[0072] Figure 6 Photos of the near-infrared LED device prepared in Application Example 1, showing no current under natural light and with current through a 650nm filter, are provided, along with the device's electroluminescence spectrum. As the drive current increases from 20mA to 350mA, the luminous intensity continues to increase without exhibiting light saturation. At a drive current of 350mA, the device achieves a maximum output power of 123.5mW, with a photoelectric conversion efficiency of 12.1%.

[0073] Figure 7 The electroluminescence spectra of the near-infrared LED device before and after 30 days of operation are shown in Figure 2. After 30 days of continuous operation, the electroluminescence intensity of the near-infrared LED device is 96.5% of the original electroluminescence intensity.

[0074] Figure 8Figure 3 is a schematic diagram of the morphology of butter leaf lettuce; Figure a is a front view comparison, and Figure b is an overall comparison. The external morphology (leaf width, diameter, and root development) of the lettuce plants in the experimental group (NIR) using the composite light source of the homemade near-infrared LED of the present invention was significantly better than that of the control group (CK).

[0075] In addition to the external morphology, the internal functional components of butter leaf lettuce were also analyzed and compared. Figure 9 As can be seen, the experimental group using the near-infrared LED prepared in Application Example 1 for supplemental lighting outperformed the control group in all growth indicators. Compared with the control group, the experimental group had a 13% increase in dry weight, a 19% increase in fresh weight, a 5% increase in chlorophyll a, a 25% increase in chlorophyll b, a 140% increase in plant length, and a 64% increase in plant width. This demonstrates that the near-infrared LED light source of the present invention has a significant effect in plant growth supplemental lighting applications.

[0076] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A Cr 3+ Activated near-infrared phosphor, characterized by, The chemical formula of near-infrared phosphor is Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ ; Among them, the value range of y is 0.1 to 0.6, and the value range of x is 0.01 to 0.

09.

2. A Cr as claimed in claim 1 3+ Activated near-infrared phosphor, characterized by, Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ The near-infrared emission wavelength range is 650~1100nm, among which Cr 3+ It is the near-infrared emission center.

3. A Cr as claimed in claim 1 3+ The method for preparing activated near-infrared phosphor is characterized by the following steps: as follows: S1. Accurately weigh the raw materials according to the stoichiometric ratio of each element in the chemical formula; S2. All raw materials of the ingredients were placed in an agate mortar, and anhydrous ethanol was added for wet grinding to obtain a slurry mixture; grinding for 15-25 minutes until the anhydrous ethanol was completely evaporated to obtain a powdered mixture; S3. The mixture was poured into a crucible, placed in a muffle furnace, and calcined to obtain a calcined product; S4. After cooling to room temperature, the calcined product was removed from the muffle furnace and ground again for 5-15 minutes to obtain the near-infrared phosphor Gd 1-y Y y Al 3-x (BO3)4:xCr 3+ .

4. A Cr as claimed in claim 3 3+ The method for preparing activated near-infrared phosphor is characterized by the following steps: In S1, the raw materials are Gd2O3, Y2O3, Al2O3, Cr2O3, and H3BO3.

5. A Cr as claimed in claim 3 3+ The method for preparing activated near-infrared phosphor is characterized by: In step S3, calcination is performed at 1000-1300° C. for 5-7 hours.

6. A Cr as claimed in claim 3 3+ Cr prepared by the preparation method of activated near-infrared phosphor 3+ Application of activated near-infrared phosphors in the preparation of near-infrared LEDs.

7. A Cr as claimed in claim 3 3+ Cr prepared by the preparation method of activated near-infrared phosphor 3+ Application of activated near-infrared phosphors in plant lighting.

8. The use according to claim 6, wherein Cr 3+ The activated near-infrared phosphor is combined with a commercial 450nm blue LED chip to produce a near-infrared LED. The near-infrared LED device emits light in the wavelength range of 650 to 1100nm.

9. The use according to claim 7, characterized in that: Cr 3+ The activated near-infrared phosphor is compounded with a commercial 450nm blue light LED chip to obtain a near-infrared LED; the near-infrared LED is used as a light source for plant supplementary lighting.

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