A type of Er 3+ / Sm 3+ Preparation method of co-doped BaFCl color-tunable phosphor

Abstract

This invention provides an Er 3+ / Sm 3+ The preparation method of co-doped BaFCl color-tunable phosphor belongs to the field of luminescent materials technology, solving the technical challenges of luminescence color regulation and luminescence performance instability of rare earth ion-doped nanomaterials. The technical solution is based on Er... 3+ and Sm 3+ Color-tunable phosphors were prepared by co-doping BaFCl nanoparticles with Sm. 3+ By adjusting the doping concentration, color tuning from yellow-green to orange-red light can be achieved. The beneficial effect of this invention is that by changing the Sm... 3+ By adjusting the doping concentration, color tuning can be achieved, ranging from yellow-green to orange-red light.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to the technology of preparing phosphors from rare-earth ion-doped nanoparticles and the analysis of the luminescent properties of luminescent materials, particularly to an Er... 3+ / Sm 3+ Preparation method of co-doped BaFCl color-tunable phosphor. Background Technology

[0002] With the development of science and technology, the potential of rare earth elements is being explored in greater depth. Rare earth elements (Ln) generally refer to the lanthanide elements (such as lanthanum (La), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.) and yttrium (Y). They exhibit excellent optical properties due to their unique electronic structure. Rare earth ions possess high spectral purity and stable luminescence properties, and are widely used in fluorescent materials, lasers, optoelectronic displays, and bioimaging. These elements, with their unique properties and broad application prospects, are gradually becoming an important force driving technological progress and industrial upgrading. Rare earth ion-doped nanoparticles can generally be divided into single rare earth ion doping and multi-rare earth ion co-doping, each with different characteristics:

[0003] 1. Single rare earth ion doping: Single rare earth ion doping has the following characteristics: (1) clear luminescence characteristics (single rare earth ion doping usually produces luminescence at a specific wavelength, which makes its luminescence characteristics very clear); (2) simple energy transfer mechanism (since there is only one rare earth ion, the energy transfer mechanism is relatively simple, mainly relying on the characteristic transition of the ion); (3) high quantum efficiency (because there is no competition or interference from other ions, single-doped materials usually have high quantum efficiency); (4) optimization of doping concentration (by adjusting the doping concentration, the luminescence intensity can be optimized, but excessively high concentration may lead to concentration quenching); (5) simple and clear application (single-doped materials are usually used for specific applications, such as red phosphors, lasers, etc., which facilitates application development in specific fields). This also makes its application very widespread. In order to achieve the upconversion effect of multicolor orthogonal luminescence, and at the same time regulate the synthesis complexity and mutual interference problems brought about by multiple doped ions, Er 3+ The mechanism by which special energy level transitions produce different colors of light was studied, and a method based on Er was designed. 3+Single-doped dual-excitation upconversion nanoparticles were used as activators, and a three-layer nanoparticle structure was constructed using a thermal decomposition method. The prepared nanoparticles exhibited uniform size, stable structure, and good dispersibility. These unique dual-excitation nanoparticles could achieve orthogonal red and green emission under two excitation light sources (980 nm and 808 nm), respectively, with each emission performance remaining independent and unaffected by the others. Furthermore, a novel near-infrared luminescent material, Mg, was synthesized using a high-temperature solid-state method. 2 - x SnO4∶x Cr 3+ The structure of the sample was characterized by X-ray powder diffraction, and the results showed that the obtained phosphor had a single spinel structure and was doped with Cr. 3+ The ions did not alter its crystal structure. The luminescence properties of the phosphor were investigated in detail using fluorescence spectroscopy and fluorescence decay spectroscopy. The results showed that the fluorescence lifetime of the sample increased with increasing Cr content. 3+ The decrease gradually increases with increasing doping concentration, indicating that Cr 3+ Energy transfer occurs between them.

[0004] 2. Co-doping with multiple rare earth ions: The characteristics of co-doping with multiple rare earth ions include (1) luminescence color adjustment (co-doping can achieve luminescence color adjustment through the combination of different rare earth ions); (2) enhanced energy transfer (energy transfer between different rare earth ions can significantly enhance luminescence efficiency, especially in co-doped systems, energy transfer can improve luminescence intensity); (3) broad spectrum luminescence (co-doped materials can emit light in a wider spectral range, increasing the flexibility of applications, such as for full-color light-emitting devices); (4) complex luminescence mechanism (the luminescence mechanism of co-doping is relatively complex, involving the energy level interaction and energy transfer of multiple ions, which may require in-depth research to understand its luminescence behavior); (5) wide application (co-doped materials have a wider range of applications, and can be used in optoelectronic devices, display systems, bioimaging and other fields, with greater market potential). This makes it a popular research object at present, and Tb co-doped in silicate and borosilicate glasses 3+ and Sm 3+ The photoluminescence properties of ions. Under ultraviolet light irradiation, these glass materials emit a combination of green and orange-red light waves, creating a white light effect. The intensity ratio of orange-red to green light can be adjusted by controlling the Sm... 3+ Flexible control is achieved by adjusting the ion concentration and changing the glass matrix composition. Using a wet chemical method, co-doped Er... 3+ and Sm 3+ZnS semiconductor quantum dots (QDs) containing ions. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to verify the presence of Er in the ZnS matrix. 3+ and Sm 3+ The existence of.

[0005] Rare-earth ion-doped nanoparticles exhibit excellent luminescence properties, making rare earth elements an important raw material for phosphor preparation. Many researchers are now focusing on obtaining high-performance phosphors based on rare-earth ion doping. Rare-earth ion-doped phosphors possess advantages such as rich spectral lines, good optical stability, long luminescence lifetime, good chemical stability, and low biotoxicity. Numerous energy level transitions generate abundant and relatively sharp emission spectral lines, covering a broad range from ultraviolet to near-infrared. They have already been applied in many fields, including high-power lasers, solar cells, color displays, light-emitting diodes, optical anti-counterfeiting, and biomedical imaging.

[0006] With the continuous advancement and innovation of energy-saving lighting technologies, semiconductor lighting technology, with light-emitting diodes (LEDs) at its core, has developed rapidly. In LEDs, phosphors, as key light-emitting materials, directly determine the luminous efficiency and color quality of the device. Among them, white LEDs (WLEDs), with their high efficiency, multifunctionality, and wide adaptability, have been widely used in medical lighting, plant growth lighting, and health lighting. Commercial WLEDs mainly utilize blue LED chips and K2SiF6:Mn... 4+ The combination of KSFM microcrystals and CsPbBr3 nanocrystals was used to prepare the device. However, this type of device has significant technical drawbacks: due to the lack of red light component, its color temperature is too high and its color rendering index is low, resulting in problems such as insufficient light saturation and color distortion in daily lighting, making it difficult to meet the needs of high-quality lighting.

[0007] Existing technologies still face numerous challenges in achieving precise control over luminescence performance and the controllability of material preparation. For example, erbium-doped GaN with different doping concentrations was grown using ammonia-based molecular beam epitaxy. Concentration quenching of luminescence related to Er was observed in PL measurements, indicating that the optimization of luminescence performance in rare-earth ion-doped nanomaterials is highly dependent on the energy transfer efficiency between dopant ions. However, when the doping concentration exceeds a certain range, the luminescence intensity and color control stability show a significant decrease due to the concentration quenching effect, limiting its applications. Furthermore, the research by Zhu et al. further demonstrates that achieving continuous adjustment of luminescence color from green to red by changing the doping concentration of rare-earth ions is a complex technical challenge. This requires not only precise control of ion distribution at various doping concentrations but also ensuring high crystallinity of the nanoparticles during material preparation to avoid non-radiative energy transitions caused by lattice defects, thereby maintaining stable luminescence performance. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention aims to propose an Er... 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphors achieves highly efficient tunable luminescence ranging from yellow-green to orange-red, while maintaining high crystallinity and stability of the material. Specifically, this is achieved by introducing precisely controlled doping concentrations and optimized laser excitation methods, thus solving the technical challenges of luminescence color regulation and luminescence performance stability in rare-earth ion-doped nanomaterials. Based on Er... 3+ and Sm 3+ Color-tunable phosphors were prepared by co-doping BaFCl nanoparticles with Sm. 3+ By adjusting the doping concentration, color tuning can be achieved, ranging from yellow-green to orange-red light.

[0009] The inventive concept of this invention is as follows: This invention prepares color-tunable phosphors based on a rare-earth ion co-doping method. Among all trivalent lanthanide ions, Er... 3+ and Sm 3+ Both possess long-lived excited states and excellent orange-red luminescence, making them widely used as good ET sensitizers and activators. Among the matrix materials, oxide and fluoride nanoparticles are two common host materials. Oxide nanoparticles exhibit good chemical and thermal stability, while fluorine nanoparticles possess excellent energy transfer efficiency and a long fluorescence lifetime. Therefore, Er... 3+ and Sm 3+ This invention focuses on ion-doped BaFCl nanoparticles. By using rare-earth ion-doped nanoparticles to prepare phosphors, it achieves color tuning from yellow-green to orange-red under visible light excitation. The main implementation process is as follows: The BaFCl used in the experiment: Er... 3+ / Sm 3+ The nanoparticles were prepared by a simple chemical co-precipitation method in aqueous solution. All raw materials (NH4F (ACS reagent, ≥98%), ErCl3·6H2O (99.9%), SmCl3·6H2O (99.9%), BaCl2·2H2O (99.9%)) were purchased from Sigma-Aldrich and were not further purified.

[0010] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: an Er 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor includes the following steps:

[0011] Step 1: At room temperature, add (98-x) mol% BaCl2·2H2O, 2 mol% ErCl3·6H2O, and x mol% SmCl3·6H2O to 25 ml of water and stir (sonicate) to dissolve; x = 0, 0.5, 1.0, 1.5, 2.0.

[0012] Step 2: After the solution becomes transparent, let the resulting mixture stand for about half an hour, and then slowly add 25 ml of an aqueous solution containing 0.01 mol of NH4F to the solution prepared in Step 1 while stirring vigorously.

[0013] Step 3: Separate the obtained nanocrystal precipitate from the solution by centrifuging at 4000 rpm for 12 min and pour off the supernatant.

[0014] Step 4: Wash the obtained particles with ethanol 3-5 times, and finally dry the sample at 70℃ for 12 hours.

[0015] The transmission electron microscopy (TEM) and X-ray diffraction (XRD) images of the prepared nanoparticles are as follows: Figure 1 In the middle, (a) and (b) are shown.

[0016] Step 5: Use a 527 nm nanosecond pulsed laser as the excitation source to observe the transient emission process.

[0017] In step five, the advantages of nanosecond pulsed lasers over continuous laser pulses are that they have higher peak power and monochromators have the advantage of wavelength resolution, allowing for the analysis of their spectra and dynamic processes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. In the experiment of this invention, rare earth ions (Er) are used. 3+ and Sm 3+ BaFCl nanoparticles were co-doped and excited using the same laser power (112 mW) to fix Er. 3+ Concentration, change Sm 3+ The doping concentration was measured to be 2.0 mol% Er. 3 + / x mol% Sm 3+ Fluorescence spectra of co-doped nanoparticles (x=0, 0.5, 1.0, 1.5, and 2.0) are as follows: Figure 3 As shown.

[0020] 2. From Figure 2 It can be seen from Sm 3+ When the doping concentration increases from 0 mol% to 2 mol%, Sm 3+The spectral peak intensities gradually increase at 596 nm, 642 nm, and 700 nm. It is noteworthy that Er... 3+ The spectral intensities at its characteristic emission peaks of 665 nm, 800 nm, and 847 nm showed a significant decrease. This indicates that Sm... 3+ The increase in doping concentration affects Er 3+ The emission of Sm was significantly suppressed. Subsequently, measurements were taken using a monochromator and PMT to determine the emission levels of different Sm values. 3+ Er at doping concentration 3+ The dynamic evolution of luminescence at 847 nm and the decay of fluorescence lifetime further confirm the above experimental results. The ET efficiency φ increased from 7.9% to 47%, indicating that the prepared nanoparticle sample achieved luminescence evolution from Er... 3+ To Sm 3+ The efficient ET process.

[0021] 3. The corresponding CIE coordinate diagram is summarized in this invention as follows: Figure 3 As shown in the image, we can clearly see that the color hue of the sample gradually changes from yellowish-green to orange-red. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0023] Figure 1 (a) shows a transmission electron microscope (TEM) image revealing the uniformity and distribution of the nanoparticles.

[0024] Figure 1 (b) shows the XRD patterns, both doped samples exhibit sharp and clear diffraction peaks, indicating that the samples have a good crystal structure. This is a schematic diagram comparing the XRD patterns with the standard BaFCl data.

[0025] Figure 2 This invention achieves 2.0 mol% Er at a laser power of 112 mW. 3+ / x mol% Sm 3+ Fluorescence spectra of co-doped nanoparticles (x = 0, 0.5, 1.0, 1.5, and 2.0).

[0026] Figure 3 This invention relates to Er at different Sm3+ concentrations. 3+ / Sm 3+ CIE chromaticity diagram of co-doped BaFCl phosphor. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] Example 1, see Figure 2 and Figure 3 The technical solution provided in this embodiment is an Er 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor: At room temperature, 249.440 mg of 98 mol% BaCl2·2H2O and 7.634 mg of 2 mol% ErCl3·6H2O were weighed and added to 25 ml of deionized water. The mixture was stirred vigorously and allowed to stand at room temperature for about half an hour. Subsequently, under vigorous stirring, an equal volume of an aqueous solution containing 0.01 mol NH4F was added dropwise to the solution prepared in the previous step. The obtained nanoparticles were separated by centrifugation and then washed several times with ethanol. The final product was dried at 70 °C for 12 hours to obtain powdered trivalent rare earth ErCl3. 3+ Yellow-green fluorescent material doped with BaFCl nanoparticles.

[0029] Example 2, see Figure 2 and Figure 3 The technical solution provided in this embodiment is an Er 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor: At room temperature, 236.997 mg of 97 mol% BaCl2·2H2O, 7.634 mg of 2 mol% ErCl3·6H2O, and 3.648 mg of 1 mol% SmCl3·6H2O were weighed and added to 25 ml of deionized water. The mixture was stirred vigorously and allowed to stand at room temperature for about half an hour. Subsequently, under vigorous stirring, an equal volume of an aqueous solution containing 0.01 mol NH4F was added dropwise to the solution prepared in the previous step. The obtained nanoparticles were separated by centrifugation and then washed several times with ethanol. The final product was dried at 70 °C for 12 hours to obtain powdered trivalent rare earth SmCl3. 3+ and Er 3+ Yellow fluorescent material co-doped with BaFCl nanoparticles.

[0030] Example 3, see Figure 2 and Figure 3 The technical solution provided in this embodiment is an Er 3+ / Sm 3+A method for preparing co-doped BaFCl color-tunable phosphor: At room temperature, 234.553 mg of 96 mol% BaCl2·2H2O, 7.634 mg of 2 mol% ErCl3·6H2O, and 7.296 mg of 2 mol% SmCl3·6H2O were weighed and added to 25 ml of deionized water. The mixture was stirred vigorously and allowed to stand at room temperature for about half an hour. Subsequently, under vigorous stirring, an equal volume of an aqueous solution containing 0.01 mol NH4F was added dropwise to the solution prepared in the previous step. The obtained nanoparticles were separated by centrifugation and then washed several times with ethanol. The final product was dried at 70 °C for 12 hours to obtain powdered trivalent rare earth SmCl3·6H2O. 3+ and Er 3+ Orange-red fluorescent material co-doped with BaFCl nanoparticles.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A kind of Er 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor, characterized in that, Includes the following steps: Step 1: At room temperature, add (98-x) mol% BaCl2·2H2O, 2 mol% ErCl3·6H2O, and x mol% SmCl3·6H2O to 25 ml of water, stir and sonicate to dissolve; x = 0.5, 1.0, 1.5, or 2.

0. Step 2: After the solution becomes transparent, let the resulting mixture stand for half an hour, and then slowly add 25 ml of an aqueous solution containing 0.01 mol of NH4F to the solution prepared in Step 1 while stirring vigorously. Step 3: Separate the obtained nanoparticle precipitate from the solution by centrifuging at 4000 rpm for 12 min, and pour off the supernatant; Step 4: Wash the obtained particles with ethanol 3-5 times, and finally dry the sample at 70℃ for 12 hours; Step 5: Use a 527 nm nanosecond pulsed laser as the excitation source to observe the transient emission process.

2. The Er as described in claim 1 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor, characterized in that, In step one, at room temperature, take 25 ml of distilled water and pour it into a clean beaker or container. Then, weigh out (98-x) mol% BaCl2·2H2O, 2 mol% ErCl3·6H2O, and x mol% SmCl3·6H2O one by one and add them to the water. At the same time, stir with a magnetic stirrer and use ultrasound to promote dissolution. Continue stirring and sonicating until the solution is completely clear, ensuring that all solutes are completely dissolved to form a homogeneous and transparent solution.

3. The Er as described in claim 1 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor, characterized in that, The transparent solution obtained in step one is allowed to stand for about 30 minutes to ensure its stability. Meanwhile, 0.01 mol of NH4F is weighed and completely dissolved in another 25 ml of distilled water to prepare a homogeneous NH4F aqueous solution. Under vigorous stirring, the NH4F solution is slowly added dropwise to the solution in step one using a burette or pipette. The addition rate should be controlled at one drop per second. After the addition is complete, stirring is continued for 10-20 minutes to ensure that the mixture reacts uniformly.

4. The Er as described in claim 1 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor, characterized in that, In step two, the mixture after the reaction is complete is transferred to a centrifuge tube and centrifuged at 4000 rpm for 12 minutes. After centrifugation, the supernatant is poured off, and the white nanoparticle precipitate at the bottom is retained.

5. The Er as described in claim 1 3+ / Sm 3+ A method for preparing co-doped BaFCl color-tunable phosphor, characterized in that, In step four, after pouring out the clear liquid, the nanoparticles are washed with ethanol 3-5 times, then transferred to a clean desiccator and placed in a constant temperature oven at 70°C for 12 hours to remove moisture and ethanol. After drying, the collected nanoparticle powder is the final Er... 3+ / Sm 3+ Co-doped BaFCl phosphor.

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