Phosphate up-conversion luminescent material and preparation method thereof
A highly crystalline and homogeneous phosphate upconversion luminescent material was prepared by mixing a rare earth ion solution with a phosphorus source in an ice-water bath using a microwave synthesis method and then reacting the mixture with microwave radiation. This method solves the problems of high energy consumption, long cycle time, and uneven doping in the synthesis of existing gadolinium pyrophosphate-based materials, and improves the luminescent performance and stability of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUIZHOU UNIV
- Filing Date
- 2026-02-11
- Publication Date
- 2026-06-19
AI Technical Summary
Existing methods for synthesizing gadolinium pyrophosphate-based materials suffer from problems such as high energy consumption, long production cycles, uneven distribution of doped ions, high equipment requirements, and high preparation costs, which affect their application in the fields of optoelectronics and sensing.
A microwave synthesis method was used to prepare a phosphate upconversion luminescent material with high crystallinity and good uniformity by mixing a rare earth ion solution with a phosphorus source in an ice-water bath and then radiating it in a microwave reactor.
This study enables the rapid low-temperature preparation of high-purity, highly uniform phosphate upconversion luminescent materials, improving the luminescent performance and stability of the materials while reducing energy consumption and preparation costs.
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Figure CN122234801A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of inorganic luminescent materials technology, specifically relating to a phosphate upconversion luminescent material and its preparation method. Background Technology
[0002] Gadolinium pyrophosphate (Gd4(P2O7)3), as an important inorganic luminescent matrix material, has broad application prospects in lasers, display devices, and optical temperature measurement due to its high chemical stability, excellent thermal stability, and superior luminescent properties. Among them, erbium ions (Er...) 3+ ) and ytterbium ions (Yb 3+ Co-doped gadolinium pyrophosphate system, using Yb³ + Highly efficient absorption of near-infrared light and its conversion to Er³ + Its energy transfer can achieve a significant upconversion luminescence effect, that is, converting low-energy photons into high-energy visible light emission, a characteristic that has attracted widespread attention from researchers.
[0003] Currently, the synthesis of gadolinium pyrophosphate-based materials mainly relies on the traditional high-temperature solid-state method. This method typically uses gadolinium oxide (Gd₂O₃), ammonium hydrogen phosphate (NH₄H₂PO₄), or corresponding rare earth oxides as raw materials. After thorough mechanical grinding and mixing, the mixture is calcined in air at high temperature for an extended period (several hours to tens of hours) to obtain a pure phase product with good crystallinity. Although this method is direct and easy to scale up, its inherent drawbacks are also quite prominent: First, the high-temperature, long-duration sintering process consumes a huge amount of energy, resulting in a long production cycle and poor economic efficiency; second, the slow ion diffusion rate in the solid-state reaction easily leads to uneven distribution of dopant ions, affecting the consistency of luminescence performance; third, the high-temperature environment easily causes abnormal grain growth and severe agglomeration of the product, often requiring subsequent secondary grinding treatment. This process may introduce lattice defects, surface damage, or impurity contamination, thereby reducing the luminescence intensity and stability of the material; in addition, this method has stringent requirements for the high-temperature tolerance of the equipment, further increasing the preparation cost and technical threshold.
[0004] To lower the reaction temperature and improve product uniformity, researchers have explored various wet chemical synthesis routes, such as coprecipitation, hydrothermal, and solvothermal methods. Coprecipitation can achieve ionic mixing in solution and obtain precursors via a precipitant; however, the precipitates are often amorphous or have very low crystallinity, requiring post-treatment at higher temperatures (typically ≥800℃) to transform them into pure crystalline phases. Furthermore, component segregation is prone to occur during this process, affecting doping precision. While hydrothermal / solvothermal methods can directly crystallize at lower temperatures (typically 150-250℃) and pressures, the reaction typically lasts from several hours to several days, resulting in unsatisfactory efficiency. Simultaneously, this method relies on a closed, high-pressure reactor, placing high demands on equipment sealing and operational safety, making large-scale continuous preparation difficult, and controlling the morphology and size uniformity of the products remains challenging.
[0005] In summary, existing synthesis methods have limitations in terms of energy consumption, time, product crystal quality, doping uniformity, and process complexity, which restrict the performance optimization and practical application of rare-earth-doped gadolinium pyrophosphate upconversion luminescent materials. Therefore, developing a method for preparing gadolinium pyrophosphate-based materials with low reaction temperature, simple process, short cycle, low energy consumption, and the ability to directly obtain materials with high crystallinity, good dispersibility, and excellent luminescent properties is of significant scientific and industrial value for promoting the practical application of such materials in the fields of optoelectronics and sensing. Attached Figure Description
[0006] Figure 1 The upconversion luminescent material Gd prepared in Example 1 3.32 (P2O7)3:Er 0.08 , Yb 0.6 X-ray powder diffraction pattern.
[0007] Figure 2 The upconversion luminescent material Gd3(P2O7)3:Er prepared in Example 2 0.2 , Yb 0.8 Room temperature emission spectrum under 980 nm near-infrared light excitation.
[0008] Figure 3 The upconversion luminescent material Gd prepared in Example 3 2.4 (P2O7)3:Er 0.4 , Yb 1.2 SEM images.
[0009] Figure 4 The upconversion luminescent material Gd prepared in Comparative Example 1 of this invention 3.32 (P2O7)3:Er 0.08 , Yb 0.6 X-ray powder diffraction pattern.
[0010] Figure 5 The upconversion luminescent material Gd prepared in Comparative Example 2 of this invention 3.32 (P2O7)3:Er 0.08 , Yb 0.6 X-ray powder diffraction pattern.
[0011] Figure 6 The upconversion luminescent material Gd prepared in Comparative Example 3 of this invention 3.32 (P2O7)3:Er 0.08 , Yb 0.6 X-ray powder diffraction pattern. Detailed Implementation
[0012] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0013] A phosphate upconversion luminescent material with the general chemical formula: Gd 4(1-x-y) (P2O7)3:Er 4x , Yb 4y , where 0 < x <0.1, 0< y <0.4.
[0014] Furthermore, in the general chemical formula, 0.002 ≤ x <0.03, 0.05≤ y <0.2.
[0015] In a preferred embodiment, x is 0.02 and y is 0.15.
[0016] In a preferred embodiment, x is 0.05 and y is 0.2.
[0017] In a preferred embodiment, x is 0.1 and y is 0.3.
[0018] A method for preparing a phosphate upconversion luminescent material includes the following steps:
[0019] S1, according to the general chemical formula Gd 4(1-x-y) (P2O7)3:Er 4x , Yb 4y The molar ratio of elements is clearly defined. The source solutions of Gd, Er and Yb are thoroughly mixed to obtain a mixed rare earth ion solution. S2. Place the mixed rare earth ion solution in an ice-water bath and stir continuously. Add acid to adjust the pH of the solution. Then, add phosphorus-containing compounds according to the molar ratio of P element to obtain a homogeneous precursor solution. S3. Place the precursor solution in a microwave reactor and microwave irradiate it for a period of time to obtain a suspension; cool the suspension naturally to room temperature, collect the solid product and wash it, and then dry it in an oven to obtain the phosphate upconversion luminescent material.
[0020] Furthermore, the present invention does not impose strict limitations on the preparation methods of the source solutions of Gd, Er and Yb elements; the Gd, Er and Yb elements may be derived from their oxides or their soluble salts.
[0021] In one embodiment, in step S1, gadolinium oxide (Gd₂O₃), erbium oxide (Er₂O₃), and ytterbium oxide (Yb₂O₃) are dissolved in concentrated nitric acid to prepare a source solution. Further, the gadolinium oxide, erbium oxide, and ytterbium oxide are simultaneously dissolved in concentrated nitric acid to prepare a source solution, or the gadolinium oxide, erbium oxide, and ytterbium oxide are separately dissolved in concentrated nitric acid and then mixed to prepare a source solution.
[0022] In another embodiment, in step S1, the Gd salt, Er salt and Yb salt are dissolved in the solution individually or simultaneously to form a source solution.
[0023] Furthermore, the Gd salt, Er salt, and Yb salt are independently selected from at least one of their chlorides, nitrates, acetates, and sulfates; preferably, the Gd salt, Er salt, and Yb salt are their nitrates.
[0024] Further, in the mixed rare earth ion solution, the total concentration of metal ions is 0.01-5 mol / L; preferably 0.01-3 mol / L; more preferably 0.1-1 mol / L; for example, but not limiting, the total concentration of metal ions in the mixed rare earth ion solution is 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L, 0.1 mol / L, etc.
[0025] Further, the ice-water bath temperature in S2 is 0-10℃, and examples, but not limited to, ice-water bath temperatures are 0-1℃, 0-3℃, 0-5℃, 0-7℃, 0-9℃, 1-8℃, 1-6℃, 1-5℃, 1-3℃, 2-4℃, 2-5℃, 2-6℃, 2-8℃, 2-10℃, 3-5℃, 3-7℃, 3-8℃, 4-5℃, 4-7℃, 5-8℃, 6-9℃, etc.; the preferred ice-water bath temperature is 0-5℃.
[0026] Furthermore, acid is added to S2 to adjust the pH to 0-3, preferably 0-1.
[0027] Furthermore, the acid used to adjust the pH includes, but is not limited to, at least one of nitric acid, hydrochloric acid, phosphoric acid, and sulfuric acid, preferably nitric acid and / or phosphoric acid.
[0028] Further, the phosphorus-containing compound is selected from at least one of alkali metal and / or ammonia orthophosphates, hydrogen phosphates, pyrophosphates, hydrogen pyrophosphates, dihydrogen pyrophosphates, and trihydrogen pyrophosphates; preferably, the phosphorus-containing compound is selected from alkali metal and / or ammonia pyrophosphates.
[0029] In one embodiment, the phosphorus-containing compound is ammonium pyrophosphate and / or sodium pyrophosphate.
[0030] Furthermore, the microwave radiation power range in S3 is 300-850W, with example but not limited microwave radiation powers of 300W, 350W, 400W, 450W, 500W, 550W, 600W, 650W, 700W, 750W, 800W, 850W, etc.; the microwave response time is 1-60min.
[0031] Furthermore, the microwave radiation power ranges from 700 to 800 W, and the microwave response time is 5 to 20 minutes.
[0032] Furthermore, the drying temperature is 60-120℃ and the drying time is 1-12h; the preferred drying temperature is 80-100℃ and the drying time is 3-6h.
[0033] Furthermore, the method of collecting solid products in S3 includes, but is not limited to, at least one of filtration, vacuum filtration, and centrifugal separation; centrifugal separation is preferred.
[0034] Furthermore, the reagents used to clean the solid products are deionized water and / or anhydrous ethanol.
[0035] Example 1 This embodiment provides a phosphate upconversion luminescent material with the general chemical formula: Gd 3.32 (P2O7)3:Er 0.08 ,Yb 0.6The preparation method includes the following steps: S1. Using high-purity gadolinium oxide, erbium oxide, and ytterbium oxide as starting materials, they are dissolved separately in heated concentrated nitric acid to prepare a clear nitrate solution of Gd(NO3)3, Er(NO3)3, and Yb(NO3)3 with a concentration of 0.5 mol / L. Subsequently, according to the molar ratio of Gd, Er, and Yb elements in the above chemical formula, the corresponding volume of the above nitrate solution is accurately measured into a beaker and a certain volume of deionized water is added. The mixture is stirred evenly under magnetic stirring to obtain a mixed rare earth ion solution with a total rare earth ion concentration of 0.3 mol / L.
[0036] S2. Place the mixed rare earth ion solution in an ice-water bath at 0-5°C and stir continuously, while slowly adding dilute nitric acid to adjust the pH of the solution to 0.8. Maintain the ice-water bath and stirring conditions, weigh out the corresponding amount of ammonium pyrophosphate ((NH4)4P2O7) as the phosphorus source according to the stoichiometric ratio of P to Gd, and slowly add it to the mixed solution. Continue stirring for 30 minutes to ensure thorough mixing and obtain the precursor solution.
[0037] S3. Transfer the precursor solution to a round-bottom flask and place it in a microwave synthesizer. Incubate at 800 W for 12 min, during which a white suspension will gradually form. After the reaction, allow the suspension to cool naturally to room temperature. Collect the white solid product by centrifugation and wash it three times each with deionized water and anhydrous ethanol. Finally, dry the product in a 90°C oven for 3 h to obtain a white powdered Gd. 3.32 (P2O7)3:Er 0.08 , Yb 0.6 The upconversion luminescent material, its X-ray powder diffraction pattern is attached. Figure 1 .
[0038] Example 2 This embodiment provides a phosphate upconversion luminescent material with the general chemical formula: Gd3(P2O7)3:Er 0.2 ,Yb 0.8 The preparation method includes the following steps: S1. Using gadolinium nitrate, erbium nitrate, and ytterbium nitrate as starting materials, prepare a clear nitrate solution of Gd(NO3)3, Er(NO3)3, and Yb(NO3)3 with a concentration of 0.2 mol / L. According to the molar ratio of Gd, Er, and Yb elements in the above chemical formula, accurately measure the corresponding volume of the above nitrate solution into a beaker and add a certain volume of deionized water. Mix evenly under magnetic stirring to obtain a mixed rare earth ion solution with a total rare earth ion concentration of 0.1 mol / L.
[0039] S2. Place the mixed rare earth ion solution in an ice-water bath at 3-5°C and stir continuously. Slowly add dilute nitric acid to adjust the pH of the solution to 0.5. Maintain the ice-water bath and stirring conditions. Weigh out the corresponding amount of sodium pyrophosphate (Na4P2O7) as the phosphorus source according to the stoichiometric ratio of P to Gd. Slowly add it to the mixed solution and continue stirring for 30 minutes to ensure thorough mixing and obtain the precursor solution.
[0040] S3. Transfer the precursor solution to a round-bottom flask and place it in a microwave synthesizer. Irradiate the mixture at 500 W for 25 min, during which a suspension will gradually form. After the reaction, allow the suspension to cool naturally to room temperature. Collect the solid product by centrifugation and wash it three times each with deionized water and anhydrous ethanol. Finally, dry the product in an oven at 80°C for 8 h to obtain powdered Gd3(P2O7)3:Er 0.2 , Yb 0.8 The upconversion luminescent material and its room-temperature emission spectrum under 980 nm near-infrared light excitation are shown in the appendix. Figure 2 .
[0041] Example 3 This embodiment provides a phosphate upconversion luminescent material with the general chemical formula: Gd 2.4 (P2O7)3:Er 0.4 ,Yb 1.2 The preparation method includes the following steps: S1. Using gadolinium acetate, erbium acetate, and ytterbium acetate as starting materials, prepare solutions with a concentration of 1.0 mol / L. Based on the molar ratio of Gd, Er, and Yb elements in the above chemical formula, accurately measure the corresponding volume of the above solutions into a beaker and add a certain volume of deionized water. Mix evenly under magnetic stirring to obtain a mixed rare earth ion solution with a total rare earth ion concentration of 1 mol / L.
[0042] S2. Place the mixed rare earth ion solution in an ice-water bath at 0-10°C and stir continuously, while slowly adding concentrated phosphoric acid to adjust the pH of the solution to 1.5. Maintain the ice-water bath and stirring conditions, and use a mixture of ammonium dihydrogen phosphate (NH4H2PO4) and ammonium pyrophosphate in a molar ratio of 1:1 as the phosphorus source. According to the stoichiometric ratio of P to Gd, slowly add the corresponding amount of phosphorus source to the mixed solution, and continue stirring for 30 minutes to ensure thorough mixing and obtain the precursor solution.
[0043] S3. Transfer the precursor solution to a round-bottom flask and place it in a microwave synthesizer. Irradiate the mixture at 300 W for 50 min, during which a suspension will gradually form. After the reaction, allow the suspension to cool naturally to room temperature. Collect the solid product by centrifugation and wash it three times each with deionized water and anhydrous ethanol. Finally, dry the product in an oven at 120°C for 2 h to obtain powdered Gd3(P2O7)3:Er 0.2 , Yb 0.8 The upconversion luminescent material, its SEM image is attached. Figure 3 As can be seen, it has a uniform particle size distribution.
[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that the mixed rare earth ion solution in S2 was not placed in an ice-water bath but was continuously stirred at room temperature. The X-ray powder diffraction pattern of the luminescent material prepared in Comparative Example 1 is attached. Figure 4 .
[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that a microwave power of 200W was used in S3. The X-ray powder diffraction pattern of the luminescent material prepared in Comparative Example 2 is attached. Figure 5 .
[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that the preparation method of the phosphate luminescent material adopts a hydrothermal method, specifically: S1. Using high-purity gadolinium oxide, erbium oxide, and ytterbium oxide as starting materials, they were dissolved separately in heated concentrated nitric acid to prepare clear nitrate solutions of Gd(NO3)3, Er(NO3)3, and Yb(NO3)3 with a concentration of 0.5 mol / L. Subsequently, according to Gd... 3.32 (P2O7)3:Er 0.08 , Yb 0.6 The molar ratio of Gd, Er, and Yb in the general chemical formula is determined. The corresponding volume of the above nitrate solution is accurately measured into a beaker, and a certain volume of deionized water is added. The mixture is stirred evenly under magnetic stirring to obtain a mixed rare earth ion solution with a total rare earth ion concentration of 0.3 mol / L.
[0047] S2. Place the mixed rare earth ion solution in an ice-water bath at 0-5°C and stir continuously, while slowly adding dilute nitric acid to adjust the pH of the solution to 0.8. Maintain the ice-water bath and stirring conditions, weigh out the corresponding amount of ammonium pyrophosphate ((NH4)4P2O7) as the phosphorus source according to the stoichiometric ratio of P to Gd, and slowly add it to the mixed solution. Continue stirring for 30 minutes to ensure thorough mixing and obtain the precursor solution.
[0048] S3. The precursor solution was placed in a reaction vessel and hydrothermally reacted at 180°C for 12 hours to obtain a reaction mixture. After the reaction, the suspension was naturally cooled to room temperature, and the white solid product was collected by centrifugation. The product was then washed three times each with deionized water and anhydrous ethanol. Finally, the product was dried in an oven at 90°C for 3 hours to obtain a white powdered Gd. 3.32 (P2O7)3:Er 0.08 , Yb 0.6 The upconversion luminescent material, its X-ray powder diffraction pattern is attached. Figure 6 .
[0049] Performance testing methods and results analysis: Appendix Figure 1 Gd in Example 1 3.32 (P2O7)3:Er 0.08 , Yb 0.6 X-ray powder diffraction pattern of the upconversion luminescent material, with appendix Figure 4 The image shows the X-ray powder diffraction pattern of the luminescent material prepared in Comparative Example 1. (According to the attached image...) Figure 1 It can be seen that the sample prepared in Example 1 is a single-phase, highly crystalline Er and Yb co-doped gadolinium pyrophosphate (Gd). 3.32 (P2O7)3:Er 0.08 , Yb 0.6 Upconversion luminescent material. According to the appendix... Figure 4 It can be seen that the sample prepared in Comparative Example 1 is Er and Yb co-doped gadolinium orthophosphate Gd 0.82 PO4:Er 0.02 , Yb 0.15 With gadolinium pyrophosphate (Gd) 3.32 (P2O7)3:Er 0.08 , Yb 0.6 Mixed phase crystals and Gd 0.82 PO4:Er 0.02 , Yb 0.15 The main component is [unclear - possibly a specific ingredient or ingredient]. According to the appendix... Figure 1 and attached Figure 4 The comparison shows that placing the mixed rare earth ion solution in an ice-water bath for stirring during the preparation process is one of the key factors in obtaining pure-phase gadolinium pyrophosphate-based upconversion luminescent materials.
[0050] Appendix Figure 5 The X-ray powder diffraction pattern of the luminescent material prepared in Comparative Example 2 is shown in the attached diagram. Figure 1 and attached Figure 5 It can be seen that the product prepared in Example 1 is a highly crystalline single-phase Er and Yb co-doped gadolinium pyrophosphate (Gd). 3.32 (P2O7)3:Er 0.08 , Yb 0.6The product prepared in Example 1 was an amorphous sample, while the product prepared in Comparative Example 2 was a luminescent material. Comparing Example 1 and Comparative Example 2 demonstrates that only by strictly controlling the microwave power can the prepared luminescent material possess better crystallinity and phase purity.
[0051] Appendix Figure 6 The image shows the X-ray powder diffraction pattern of the luminescent material in Comparative Example 3. (Based on the attached image...) Figure 1 It can be seen that the sample prepared in Example 1 is a single-phase, highly crystalline Er and Yb co-doped gadolinium pyrophosphate (Gd). 3.32 (P2O7)3:Er 0.08 , Yb 0.6 Upconversion luminescent material. According to the appendix... Figure 6 It can be seen that the sample prepared in Comparative Example 3 is a single-phase Er and Yb co-doped gadolinium orthophosphate Gd 0.82 PO4:Er 0.02 ,Yb 0.15 Gadolinium pyrophosphate crystals were not obtained. According to the appendix... Figure 1 and attached Figure 6 The comparison shows that the microwave synthesis method used in this application is one of the key factors in obtaining pure-phase doped gadolinium pyrophosphate-based upconversion luminescent materials.
[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A phosphate upconversion luminescent material, characterized in that, The phosphate upconversion luminescent material has the general chemical formula: Gd 4(1-x-y) (P2O7)3:Er 4x , Yb 4y , where 0 < x <0.1, 0< y <0.
4.
2. The phosphate upconversion luminescent material according to claim 1, characterized in that, In the general chemical formula, 0.002 ≤ x <0.03, 0.05≤ y <0.
2.
3. The phosphate upconversion luminescent material according to claim 1, characterized in that, In the general chemical formula, x is 0.02 and y is 0.15; or x is 0.05 and y is 0.2; or x is 0.1 and y is 0.
3.
4. The method for preparing the phosphate upconversion luminescent material according to any one of claims 1-3, characterized in that, Includes the following steps: S1, according to the general chemical formula Gd 4(1-x-y) (P2O7)3:Er 4x , Yb 4y The molar ratio of elements is clearly defined. The source solutions of Gd, Er and Yb are thoroughly mixed to obtain a mixed rare earth ion solution. S2. Place the mixed rare earth ion solution in an ice-water bath and stir continuously, then add acid to adjust the pH of the solution; Subsequently, phosphorus-containing compounds were added to the mixture according to the molar ratio of P to obtain a homogeneous precursor solution. S3. Place the precursor solution in a microwave reactor and react with microwave radiation for a period of time to obtain a suspension. The suspension was allowed to cool naturally to room temperature, the solid product was collected and washed, and then dried in an oven to obtain the phosphate upconversion luminescent material.
5. The preparation method according to claim 4, characterized in that, The total concentration of metal ions in the mixed rare earth ion solution is 0.01-5 mol / L.
6. The preparation method according to claim 4, characterized in that, The ice-water bath temperature in S2 is 0-10℃; acid is added to S2 to adjust the pH to 0-3.
7. The preparation method according to claim 4, characterized in that, The microwave radiation power range in S3 is 300-850W, and the microwave response time is 1-60min.
8. The preparation method according to claim 4, characterized in that, In step S1, gadolinium oxide, erbium oxide, and ytterbium oxide are dissolved in concentrated nitric acid to prepare a source solution; or, Gd salt, Er salt, and Yb salt are dissolved in the solution separately or simultaneously to form a source solution; the phosphorus-containing compound is selected from at least one of alkali metal and / or ammonia orthophosphates, hydrogen phosphates, pyrophosphates, hydrogen pyrophosphates, dihydrogen pyrophosphates, and trihydrogen pyrophosphates.
9. The preparation method according to claim 7, characterized in that, The microwave radiation power ranges from 700 to 800W, and the microwave response time is 5 to 20 minutes.
10. The preparation method according to claim 4, characterized in that, The total concentration of metal ions in the mixed rare earth ion solution is 0.01-3 mol / L; acid is added to S2 to adjust the pH to 0-1.