Rare earth luminescent material with chiral nano morphology and preparation method thereof

Abstract

The invention relates to the technical field of photoelectric functional materials, in particular to a rare earth luminescent material with chiral nano morphology and a preparation method thereof. The rare earth luminescent material disclosed by the invention is of a micron-scale hexagonal prism structure, and spiral chiral patterns are highlighted on the top surface and the bottom surface of the rare earth luminescent material; the chemical composition of the crystal is a hexagonal phase b-NaYF4: E, wherein E is selected from at least one of Yb < 3 + >, Er < 3 + >, Nd < 3 + > and Eu < 3 + >; according to the invention, the coordination effect of oleate anions and rare earth cations on the microcrystalline surface is adjusted by optimizing the hydrothermal synthesis reaction conditions of oleic acid, so that the microcrystalline luminescent material with the spiral surface appearance is obtained; the preparation method is simple to operate and easy to control, the prepared product is stable, the circular polarization luminescence performance is remarkable, and the preparation method is expected to become an important basis for research and application directions of chiral morphology synthesis of inorganic crystals, circular polarization light three-dimensional imaging, circular polarization optical communication and the like.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic functional materials technology, specifically to rare earth luminescent materials with chiral nanostructures and their preparation methods. Background Technology

[0002] Optical materials with chiral structures typically exhibit optical rotation, circular dichroism absorption, and circularly polarized luminescence properties, making them valuable for research and application in areas such as three-dimensional imaging, signal modulation, and high-fidelity transmission. Over the past two decades, chiral inorganic nano-optical materials have attracted considerable attention. The synthesis methods used include: (1) chiral ligand molecules inducing the growth of inorganic nanocrystals to obtain chiral asymmetric structures, such as chiral gold nanoparticles and chiral chalcogenide semiconductor quantum dots; (2) chiral organic molecules participating in the unit cell of crystals, such as chiral perovskite materials; and (3) the self-assembly of achiral nanomaterials to form chiral superstructures, such as using chiral morphologies of gels, liquid crystals, and DNA self-assembly structures as templates to induce the arrangement of inorganic nanomaterials.

[0003] Rare-earth-doped microcrystalline luminescent materials possess intrinsic characteristics such as small emission peak wavelength shift, narrow emission peak spectral band, and resistance to photobleaching. By adjusting the rare-earth dopant ions and crystal composition, the emission wavelength of rare-earth materials can cover the ultraviolet to near-infrared spectral range. Therefore, developing chiral rare-earth luminescent materials can expand the spectral diversity of circularly polarized luminescent materials, which is of great significance for research and applications in sensing, three-dimensional imaging, and photonic communication.

[0004] However, chiral rare-earth luminescent materials are rarely reported, and the structure-property relationship between the chiral morphology of rare-earth-doped crystals and circularly polarized luminescence remains unclear. Although Zhang Fan et al. reported the synthesis of chiral rare-earth fluoride microcrystals by the oleic acid hydrothermal method, they did not conduct research on the properties of circularly polarized luminescence. Summary of the Invention

[0005] To fill the aforementioned technological gap, this invention optimizes the hydrothermal synthesis method of rare earth fluoride microcrystals using oleic acid. By synergistically controlling the concentration of each reactant, the coordination effect between oleate anions and rare earth cations on the crystal surface is altered, inducing asymmetric differences in the crystallization energy barriers of adjacent crystal planes of b-NaYF4:E. This causes the growth kinetics of each crystal plane to deviate from equilibrium, resulting in a microcrystalline luminescent material with a spiral surface morphology, and confirming its circularly polarized luminescence performance.

[0006] In a first aspect, the present invention provides a rare-earth luminescent material with a chiral nanostructure, wherein the luminescent material has a micron-scale hexagonal prism structure, and both the bottom and top surfaces of the hexagonal prism have chiral textures, and the crystal chemical composition is b-NaYF4:E; wherein E is selected from Yb 3+ Er 3+ 、Nd 3+, Eu 3+ at least one of

[0007] Furthermore, the luminescent material is b-NaYF4:Yb,Er, where the doping rate of Yb 3+ is x %, and the value of x is 5 < x < 30, or 5 < x < 25, or 10 < x < 25, or x = 15 < x < 25, or x = 20, and the doping rate of Er 3+ is y %, and the value of y is 1 < y < 10, or 1 < y < 8, or 1 < y < 6, or 1 < y < 4, or y = 2.

[0008] Furthermore, the luminescent material is b-NaYF4:Eu, where the doping rate of Eu 3+ is z %, and the value of z is 1 < z < 10, or 1 < z < 8, or 3 < z < 8, or 3 < z < 6, or z = 5.

[0009] In a second aspect, the present invention provides a method for preparing a rare earth luminescent material with a chiral nanomorphology, comprising the following steps: S1. Adding an alkaline raw material into a mixed solvent of oleic acid and ethanol, and stirring evenly to obtain an alkaline coordination type emulsion; S2. Adding a fluoride raw material into the alkaline emulsion and stirring evenly, and then adding a rare earth nitrate raw material to stir to form a pre-crystallization precursor mixture; S3. Transferring the pre-crystallization precursor mixture to a hydrothermal autoclave, heating and reacting to crystallize and grow to obtain b-NaYF4:E microcrystals.

[0010] Furthermore, in S1, the alkaline raw material is selected from one of sodium hydroxide and potassium hydroxide; or, the alkaline raw material is a mixture of sodium hydroxide and potassium hydroxide, where the molar ratio of potassium hydroxide to sodium hydroxide in the feed is a:(1 - a), and the value of a is 0 < a < 0.5, or 0 < a < 0.3, or 0 < a < 0.2.

[0011] Furthermore, in S2, the fluoride raw material includes at least one of ammonium fluoride, sodium fluoride, and potassium fluoride.

[0012] Furthermore, in S2, the rare earth salt includes a matrix rare earth nitrate and a doped rare earth nitrate, and the molar ratio of the doped rare earth nitrate to the matrix rare earth nitrate in the feed is b:(1 - b), and the value of b is 0 < b < 0.5, or 0 < b < 0.3, or 0.1 < b < 0.3.

[0013] The matrix rare earth nitrate is selected from at least one of yttrium salts, gadolinium salts, lanthanum salts, and lutetium salts, or is selected from yttrium salts; And / or, the doped rare earth nitrate is selected from at least one of ytterbium salt, erbium salt, neodymium salt, and europium salt. Further, in S2, when the doped rare earth nitrate is selected from ytterbium salt and erbium salt, the matrix rare earth nitrate is selected from yttrium salt; the molar ratio of ytterbium salt, erbium salt, and yttrium salt is (0-0.2):(0-0.02):(0.78-1); or, when the doped rare earth nitrate is selected from europium salt, the matrix rare earth is selected from yttrium salt; the molar ratio of europium salt to yttrium salt is (0-0.1):(0.9-1).

[0014] Furthermore, in S3, the hydrothermal reaction conditions are: maintaining the temperature at 200-250 ℃ for 10-20 hours.

[0015] This invention optimizes the concentrations of alkali, rare earth salts, oleic acid molecules, and fluoride ions in the hydrothermal synthesis reaction of oleic acid, and regulates the coordination between oleate anions and rare earth cations on the crystal surface. This induces asymmetric differences in the crystallization energy barriers of adjacent crystal planes of b-NaYF4:E, thereby causing the growth kinetics of each crystal plane to deviate from equilibrium, resulting in microcrystalline luminescent materials with a spiral surface morphology. By synergistically changing the concentrations of each component in the hydrothermal reaction, the chiral morphology and grain size of the microcrystals can be precisely controlled. The synthesis principle of this invention is clear, the process is easy to control, the product properties are stable, and the circularly polarized luminescence performance is significant. It is expected to become an important breakthrough in research and application directions such as the synthesis of chiral morphology of inorganic crystals, three-dimensional imaging of circularly polarized light, and circularly polarized optical communication. Attached Figure Description

[0016] Figure 1 Scanning electron microscope (SEM) image of the rare earth microcrystals prepared in Example 1; in, Figure 1 a is an SEM image of the product from Example 1.1. Figure 1 b is an SEM image of the product from Example 1.2. Figure 1 c is an SEM image of the product from Example 1.3; Figure 2 SEM image of the rare earth microcrystals prepared in Example 2; in, Figure 2 a is an SEM image of the product from Example 2.1. Figure 2 b is an SEM image of the product from Example 2.2. Figure 2 c is an SEM image of the product from Example 2.3; Figure 3 SEM image of the rare earth microcrystals prepared in Example 3; in, Figure 3 a is an SEM image of the product from Example 3.1. Figure 3 b is the product of Example 3.2 SEM photos, Figure 3c is an SEM image of the product from Example 3.3; Figure 4 SEM image of the rare earth microcrystals prepared in Example 4; in, Figure 4 a is an SEM image of the product from Example 4.1. Figure 4 b is an SEM image of the product from Example 4.2. Figure 4 c is an SEM image of the product from Example 4.3; Figure 5 SEM image of the rare earth microcrystals prepared in Example 5; in, Figure 5 a is an SEM image of the product from Example 5.1. Figure 5 b is an SEM image of the product from Example 5.2. Figure 5 c is an SEM image of the product from Example 5.3; Figure 6 SEM images and photoluminescence spectra of the rare earth microcrystals prepared in Example 6; in, Figure 6 a is an SEM image of the product from Example 6. Figure 6 b is the photoexcitation / emission spectrum of the product in Example 6; Figure 7 SEM images and photoluminescence spectra of the rare earth microcrystals prepared in Example 7; in, Figure 7 a shows the SEM image of the disc-shaped rare earth microcrystals, the photoemission spectrum of a single microcrystal, and the left-handed / right-handed circularly polarized emission spectrum. Figure 7 b shows the SEM image of columnar rare earth microcrystals, the photoemission spectrum of a single microcrystal, and the left-handed / right-handed circularly polarized emission spectrum. Figure 7 c shows the SEM image of rod-shaped rare earth microcrystals, the photoemission spectrum of a single microcrystal, and the left-handed / right-handed circularly polarized emission spectrum. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are by weight. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0018] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0019] Based on the research of Zhang Fan et al., the present invention expands the variable regulation scope of the hydrothermal synthesis method of oleic acid, coordinately regulates the coordination balance among alkali metal ions, rare earth metal ions, fluoride ions, and oleate ions, induces the disproportionation of the coordination kinetics and self-assembly arrangement conformation of cis-structured oleate fluoride ions on each crystal plane of b-NaYF4:E, and further affects the crystallization kinetic barrier of each crystal plane, making the growth kinetic characteristics of each crystal plane deviate from equilibrium, thereby achieving the regulation of the chiral morphology of the crystal. Further, the present invention verifies the circularly polarized luminescence performance of the chiral morphology b-NaYF4:E crystal, and reveals the structure-activity relationship between the chiral morphology and the circularly polarized luminescence properties of rare earth inorganic crystal materials.

[0020] Please refer to Figure 1 , in some specific embodiments, the rare earth luminescent material with chiral nano-morphology is a micro-scale hexagonal prism structure, and both the bottom and top surfaces of the hexagonal prism have chiral ridges. The chiral ridges present a radial texture with the geometric center as the origin, and the fine lines (or grooves, protrusions) symmetrically distributed with six-fold axes radiate towards the edge. The line spacing is uniform and gradually fades at the edge of the hexagonal prism. The microcrystalline luminescent material with this surface morphology has circularly polarized luminescence performance. The chemical composition of the rare earth fluoride microcrystalline luminescent material is hexagonal phase b-NaYF4:E; wherein, E is selected from 3+ Yb 3+ Er 3+ Nd 3+ at least one of Eu.

[0021] In some specific embodiments, the luminescent material is b-NaYF4:Yb,Er, wherein the doping rate of Yb 3+ is x %, and the value of x is 5 < x < 30, or 5 < x < 25, or 10 < x < 25, or x = 15 < x < 25, or x = 20, and the doping rate of Er 3+ is y %, and the value of y is 1 < y < 10, or 1 < y < 8, or 1 < y < 6, or 1 < y < 4, or y = 2.

[0022] In some preferred embodiments, the luminescent material is b-NaYF4:x %Yb,y %Er, wherein x = 20 and y = 2.

[0023] In some specific embodiments, the luminescent material is b-NaYF4:Eu, wherein Eu3+ The doping rate is z%, where z ranges from 1 < z < 10, or 1 < z < 8, or 3 < z < 8, or 3 < z < 6, or z = 5.

[0024] In some other specific embodiments, a method for preparing a rare earth luminescent material with a chiral nano-morphology is provided, including the following steps: S1. Add an alkaline raw material to a mixed solution of oleic acid and ethanol, and stir evenly to form an alkaline emulsion; In some embodiments of this embodiment, the alkaline substance is selected from at least one of sodium hydroxide and potassium hydroxide; or, the alkaline raw material is a mixture of sodium hydroxide and potassium hydroxide, where the molar ratio of potassium hydroxide to sodium hydroxide is a:(1 - a), and a ranges from 0 < a < 0.5, or 0 < a < 0.3, or 0 < a < 0.2; S2. Sequentially add a fluoride raw material and a rare earth salt to the above-mentioned alkaline emulsion and stir evenly to form a pre-crystallization precursor mixture; In some embodiments of this embodiment, the fluoride raw material includes at least one of ammonium fluoride, sodium fluoride, and potassium fluoride; In some embodiments of this embodiment, the rare earth salt includes a matrix rare earth nitrate and a doped rare earth nitrate, and the molar ratio of the doped rare earth nitrate to the matrix rare earth nitrate in the feeding is b:(1 - b), where b ranges from 0 < b < 0.5, or 0 < b < 0.3, or 0.1 < b < 0.3.

[0025] In some embodiments of this embodiment, the matrix rare earth nitrate is selected from at least one of yttrium salts, gadolinium salts, lanthanum salts, and lutetium salts; In some embodiments of this embodiment, the doped rare earth nitrate is selected from at least one of ytterbium salts, erbium salts, neodymium salts, and europium salts. In some preferred embodiments, when the doped rare earth nitrate is selected from ytterbium salts and erbium salts, the matrix rare earth nitrate is selected from yttrium salts; the molar ratio of ytterbium salts, erbium salts to yttrium salts in the feeding is (0 - 0.2):(0 - 0.02):(0.78 - 1).

[0026] In some preferred embodiments, when the doped rare earth nitrate is selected from europium salts, the matrix rare earth is selected from yttrium salts; the molar ratio of europium salts to yttrium salts in the feeding is (0 - 0.1):(0.9 - 1).

[0027] S3. Transfer the pre-crystallization precursor mixture to a hydrothermal autoclave, heat and react to crystallize and grow to obtain b-NaYF4:E microcrystals.

[0028] In some embodiments of this implementation, the hydrothermal reaction conditions are: holding at 200-250 ℃ for 10-20 hours; for example, heating to 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, or 250 ℃; other specific values ​​within this range can be selected and will not be described in detail here; for example, holding at 10 h, 12 h, 14 h, 16 h, 18 h, or 20 h; other specific values ​​within this range can be selected and will not be described in detail here.

[0029] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1. Effect of alkaline raw material composition on the chiral morphology of rare earth fluoride microcrystalline luminescent materials Alkaline raw materials (NaOH, KOH), oleic acid (OA), and ethanol (C2H5OH) were mixed and stirred at room temperature for 10 min to form an alkaline coordination emulsion. NaF aqueous solution was added, and the mixture was stirred at room temperature for 20 min to form a transparent and clear equilibrium microemulsion solution. Y(NO3)3 aqueous solution was added, and the mixture was stirred at room temperature for 20 min, resulting in a white turbidity and forming a crystallization precursor mixture. The crystallization precursor mixture was transferred to a tetrafluoroethylene hydrothermal reactor and reacted under sealed conditions at 220 °C for 12 hours. After the reaction solution cooled to room temperature, ethanol was added, and the mixture was centrifuged to obtain b-NaYF4 microcrystals. The microcrystals were redispersed in cyclohexane. The three-dimensional morphology of the product prepared in this example was characterized using scanning electron microscopy (SEM).

[0031] The oleic acid hydrothermal reaction raw materials for Examples 1.1-1.3 are shown in Table 1.

[0032] Table 1. Reaction material ratios for Examples 1.1-1.3

[0033] The chiral morphology of the rare earth fluoride microcrystalline luminescent materials prepared in Examples 1.1-1.3 is as follows: Figure 1 As shown. Figure 1 As can be seen, the hydroxide ion [OH] is maintained. - With a constant input amount, increasing the proportion of KOH can lead to more pronounced protrusions at the edges of the hexagonal top / bottom surfaces of hexagonal prism microcrystals.

[0034] Example 2. Effect of alkaline raw material concentration on the chiral morphology of rare earth fluoride microcrystalline luminescent materials A basic raw material (NaOH), oleic acid (OA), and ethanol (C2H5OH) were mixed and stirred at room temperature for 10 min to form a basic coordination emulsion. NaF aqueous solution was added, and the mixture was stirred at room temperature for 20 min to form a clear, transparent equilibrium microemulsion. RE(NO3)3 aqueous solution was added, and the mixture was stirred at room temperature for 20 min, resulting in a white turbidity and forming a crystallization precursor mixture. The crystallization precursor mixture was transferred to a tetrafluoroethylene hydrothermal reactor and reacted at 220 °C for 12 hours. After cooling the reaction solution to room temperature, ethanol was added, and the mixture was centrifuged to obtain b-NaYF4:E microcrystals. The microcrystals were redispersed in cyclohexane. The three-dimensional morphology of the product prepared in this example was characterized using scanning electron microscopy (SEM).

[0035] The oleic acid hydrothermal reaction raw materials for Examples 2.1-2.3 are shown in Table 2.

[0036] Table 2. Proportions of reaction materials in Examples 2.1-2.3

[0037] The chiral morphologies of the rare-earth fluoride microcrystalline luminescent materials prepared in Examples 2.1-2.3 are as follows: Figure 2 As shown. From Figure 2 As can be seen, increasing the NaOH concentration can lead to more pronounced protrusions at the edges of the hexagonal top / bottom surfaces of the hexagonal prism microcrystals.

[0038] Example 3. Effect of rare earth ion doping composition on the chiral morphology of rare earth fluoride microcrystalline luminescent materials Mix the alkaline raw material (NaOH), oleic acid (OA), and ethanol (C2H5OH), and stir at room temperature. Stir for 10 min to form an alkaline coordination emulsion; add NaF aqueous solution and stir at room temperature for 20 min to form a transparent and clear equilibrium microemulsion solution; add RE(NO3)3 aqueous solution and stir at room temperature for 20 min to form a white turbidity, forming a crystallization precursor mixture; transfer the crystallization precursor mixture to a tetrafluoroethylene hydrothermal reactor and seal and react at 220 °C for 12 hours; after the reaction solution is cooled to room temperature, add ethanol and centrifuge to obtain b-NaYF4:E microcrystals; redisperse the microcrystals in cyclohexane; characterize the three-dimensional morphology of the product prepared in the example using scanning electron microscopy (SEM).

[0039] The oleic acid hydrothermal reaction raw materials for Examples 3.1-3.3 are shown in Table 3.

[0040] Table 3. Proportions of reaction materials in Examples 3.1-3.3

[0041] The chiral morphologies of the rare-earth fluoride microcrystalline luminescent materials prepared in Examples 3.1-3.3 are as follows: Figure 3 As shown. From Figure 3 As can be seen, keeping the amount of rare earth nitrate added constant and changing the doping composition can yield chiral microcrystals.

[0042] Example 4. Effect of reaction water content on the chiral morphology of rare earth fluoride microcrystalline luminescent materials Alkaline raw materials (NaOH, KOH), oleic acid (OA), and ethanol (C2H5OH) were mixed and stirred at room temperature for 10 min to form an alkaline coordination emulsion. NaF aqueous solution was added, and the mixture was stirred at room temperature for 20 min to form a transparent and clear equilibrium microemulsion solution. Y(NO3)3 aqueous solution was added, and the mixture was stirred at room temperature for 20 min, resulting in a white turbidity and forming a crystallization precursor mixture. The crystallization precursor mixture was transferred to a tetrafluoroethylene hydrothermal reactor and reacted under sealed conditions at 220 °C for 12 hours. After the reaction solution cooled to room temperature, ethanol was added, and the mixture was centrifuged to obtain b-NaYF4 microcrystals. The microcrystals were redispersed in cyclohexane. The three-dimensional morphology of the product prepared in this example was characterized using scanning electron microscopy (SEM).

[0043] The oleic acid hydrothermal reaction raw materials for Examples 4.1-4.3 are shown in Table 4.

[0044] Table 4. Proportions of reaction materials in Examples 4.1-4.3

[0045] The chiral morphologies of the rare-earth fluoride microcrystalline luminescent materials prepared in Examples 4.1-4.3 are as follows: Figure 4 As shown. From Figure 4 As can be seen, with the increase of water content, the microemulsion diameter increases and the volume increases, which leads to the accelerated crystallization rate of rare earth fluorides and the increase in product size (the diagonals of the top face of the hexagonal prism microcrystal are 0.9 μm, 1.1 μm, and 1.30 μm, respectively).

[0046] Example 5. Effect of alkaline raw material composition on the chiral morphology of rare earth fluoride microcrystalline luminescent materials Alkaline raw materials (NaOH, KOH), oleic acid (OA), and ethanol (C2H5OH) were mixed and stirred at room temperature for 10 min to form an alkaline coordination emulsion. NaF aqueous solution was added, and the mixture was stirred at room temperature for 20 min to form a transparent and clear equilibrium microemulsion solution. Y(NO3)3, Yb(NO3)3, and Er(NO3)3 aqueous solutions were added, and the mixture was stirred at room temperature for 20 min, resulting in a white turbidity and forming a crystallization precursor mixture. The crystallization precursor mixture was transferred to a tetrafluoroethylene hydrothermal reactor and reacted under sealed conditions at 220 °C for 12 hours. After the reaction solution cooled to room temperature, ethanol was added, and the mixture was centrifuged to obtain b-NaYF4 microcrystals. The microcrystals were redispersed in cyclohexane. The three-dimensional morphology of the product prepared in this example was characterized using scanning electron microscopy (SEM).

[0047] The oleic acid hydrothermal reaction raw materials for Examples 5.1-5.3 are shown in Table 5.

[0048] Table 5. Proportions of reactants in Examples 5.1-5.3

[0049] The chiral morphologies of the rare-earth fluoride microcrystalline luminescent materials prepared in Examples 5.1-5.3 are as follows: Figure 5 As shown. From Figure 5 As can be seen, the hydroxide ion [OH] is maintained. - With a constant input amount, increasing the proportion of KOH can cause the spiral pattern on the hexagonal top / bottom surface of the hexagonal prism microcrystals to change from convex to concave.

[0050] Example 6. Chiral morphology and spectral characteristics of europium-doped fluoride microcrystalline luminescent materials The preparation method is basically the same as in Example 1, except that 0.54 mmol of Y(NO3)3 and 0.06 mmol of Eu(NO3)3 aqueous solution.

[0051] The chiral morphology of the europium-doped fluoride microcrystals prepared is as follows: Figure 6 As shown in Figure a. The photoexcitation / emission spectrum is as follows: Figure 6 As shown in b, the material emits a main emission peak at 615 nm when excited by blue light at 395 nm.

[0052] Example 7: Circularly polarized luminescence characteristics of rare-earth fluoride microcrystalline luminescent materials Micron-sized disk-shaped (Example 5.1), micron-sized columnar (Example 5.2), and micron-sized rod-shaped (Example 5.3) b-NaYF4:Yb,Er crystal dispersions were diluted and drop-cast onto a single-crystal silicon surface. Individual microcrystal particles were located and measured using a confocal microspectroscopy system excited by a 980 nm laser. Left-handed and right-handed circularly polarized light emission was detected using a quarter-wave plate, and the luminescence asymmetry factor of each individual microcrystal particle was obtained. Figure 7 As shown, all three types of microcrystals exhibited significant circularly polarized emission signals, with g-factor values ​​ranging from 0.1 to 0.2.

[0053] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A rare-earth luminescent material with a chiral nanostructure, characterized in that, The luminescent material has a micron-scale hexagonal prism structure, and both the base and top surfaces of the prism have chiral striations. Its crystal chemical composition is b-NaYF4:E, where E is selected from Yb. 3+ Er 3+ 、Nd 3+ Eu 3+ At least one of them.

2. The chiral nanostructured rare-earth luminescent material according to claim 1, characterized in that, The luminescent material is b-NaYF4:x %Yb, y %Er, wherein x=5-30, or x=5-25, or x=10-25, or x=15-25, or x=20, and y=1-10, or y=1-8, or y=1-6, or y=1-4, or y=2.

3. The rare-earth fluoride microcrystalline luminescent material according to claim 1, characterized in that, b-NaYF4:z %Eu, where z=1-10, or z=1-8, or z=3-8, or z=3-6, or z=5.

4. A method for preparing a rare-earth luminescent material with chiral nanostructures, characterized in that, Includes the following steps: S1. Add the alkaline raw material to the mixture of oleic acid and ethanol, and stir until homogeneous to form an alkaline emulsion; S2. Fluoride raw materials and rare earth salts are added to the above alkaline emulsion in sequence and stirred evenly to form a crystallization precursor mixture; S3. The crystallization precursor mixture is placed in a hydrothermal high-pressure reactor and heated to promote crystallization growth, yielding b-NaYF4:E microcrystals.

5. The preparation method according to claim 4, characterized in that, In S1, the alkaline raw material is selected from at least one of sodium hydroxide and potassium hydroxide; or, the alkaline raw material is a mixture of sodium hydroxide and potassium hydroxide, wherein the molar ratio of potassium hydroxide to sodium hydroxide is a:(1-a), and a takes the value of 0<a<0.5, or 0<a<0.3, or 0<a<0.

2.

6. The preparation method according to claim 4, characterized in that, In S2, the fluoride raw material includes at least one of ammonium fluoride, sodium fluoride, and potassium fluoride.

7. The preparation method according to claim 4, characterized in that, In S2, the rare earth salt includes a matrix rare earth nitrate and a doped rare earth nitrate. The molar ratio of the doped rare earth nitrate to the matrix rare earth nitrate is b:(1-b), where b takes the value 0 < b < 0.5, or 0 < b < 0.3, or 0.1 < b < 0.

3.

8. The preparation method according to claim 7, characterized in that, In S2, the matrix rare earth nitrate is selected from at least one of yttrium salt, gadolinium salt, lanthanum salt, and lutetium salt, or selected from yttrium salt; and / or, the doped rare earth nitrate is selected from at least one of ytterbium salt, erbium salt, neodymium salt, and europium salt.

9. The preparation method according to claim 7, characterized in that, In S2, when the doped rare earth nitrate is selected from ytterbium salt and erbium salt, and the matrix rare earth nitrate is selected from yttrium salt; the molar ratio of ytterbium salt, erbium salt and yttrium salt is (0-0.2):(0-0.02):(0.78-1); or, when the doped rare earth nitrate is selected from europium salt, and the matrix rare earth nitrate is selected from yttrium salt; the molar ratio of europium salt and yttrium salt is (0-0.1):(0.9-1).

10. The preparation method according to claim 4, characterized in that, In S3, the hydrothermal reaction conditions are: reaction at 200-250 ℃ for 10-20 hours.

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