A preparation method of ultrafine erbium oxide nanomaterial

Abstract

The present invention relates to the technical field of rare earth material preparation, and specifically to a method for preparing ultrafine erbium oxide nanomaterials. The present invention uses ordered macroporous polystyrene as a nanoreactor, and uniformly introduces erbium salt into the pores by an impregnation method. Subsequently, ultrafast laser excitation is used to achieve instantaneous oxidation of the erbium salt to form nanoscale erbium oxide crystals. Finally, a sodium hydroxide solution is used to gently remove the ordered macroporous polystyrene to obtain high-purity erbium oxide nanopowders with uniform particle size. This method can accurately control the particle size and crystallinity by adjusting the laser parameters. The reaction process is rapid and efficient, avoiding traditional high temperature and high pressure conditions, and the process is more environmentally friendly. Sodium hydroxide selectively dissolves the carrier without damaging the erbium oxide particles, ensuring the purity and stable performance of the material. The overall solution is easy to operate, combined with advanced nanoreactor design and ultrafast laser technology, and is suitable for preparing erbium oxide nanomaterials with excellent performance and wide application.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth material preparation, and in particular to a method for preparing ultrafine erbium oxide nanomaterial. Background Art

[0002] Erbium oxide, an important functional material, is widely used in the manufacture of yttrium iron garnet additives, nuclear reactor control materials, specialty luminescent glass, and infrared-absorbing glass. It is also commonly used as a glass colorant. Its unique optoelectronic properties make erbium oxide highly valuable in photonics, optics, and communications science. Furthermore, large-particle erbium oxide is considered an excellent anti-corrosion coating material due to its excellent corrosion resistance. Its high refractive index and high transparency make it suitable for reflective coatings in devices such as solar cells. In thermonuclear experimental reactors, erbium oxide coatings serve as hydrogen barriers to prevent tritium penetration and are often used in conjunction with metallic transition layers such as Fe-Er. Erbium lasers, solid-state pulsed lasers with a wavelength of approximately 2940 nm, are widely used in medical fields such as delicate soft tissue cutting and cataract extraction due to their strong absorption by water in human tissue, showing promising development prospects.

[0003] Despite the widespread potential of erbium oxide, existing mass production technology for erbium oxide nanoparticles primarily relies on precipitation methods. However, this method suffers from slow reaction rates, long production cycles, and difficulty achieving high dispersion and uniformity of nanoparticles, particularly those with diameters in the 10-30 nm range. Furthermore, erbium oxide nanoparticles prepared by precipitation methods have a small specific surface area, limiting their application in fields such as catalysis and optics.

[0004] Therefore, developing a new process that is efficient, controllable, and capable of preparing erbium oxide nanomaterials with uniform size and good dispersion has become the key to improving their comprehensive performance and expanding their application areas. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing ultrafine erbium oxide nanomaterials. The present invention uses ordered macroporous polystyrene as a nanoreactor, and introduces erbium salts into the pores uniformly by impregnation. Subsequently, ultrafast laser excitation is used to achieve instantaneous oxidation of the erbium salts to form nanoscale erbium oxide crystals. Finally, a sodium hydroxide solution is used to gently remove the ordered macroporous polystyrene to obtain high-purity erbium oxide nanopowders with uniform particle size. This method can accurately control the particle size and crystallinity by adjusting the laser parameters. The reaction process is rapid and efficient, avoiding traditional high temperature and high pressure conditions, and the process is more environmentally friendly. Sodium hydroxide selectively dissolves the carrier without damaging the erbium oxide particles, ensuring the purity and stable performance of the material. The overall solution is simple to operate, combined with advanced nanoreactor design and ultrafast laser technology, and is suitable for the preparation of erbium oxide nanomaterials with excellent performance and wide application.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing ultrafine erbium oxide nanomaterials comprises the following steps:

[0008] S1. Add ordered macroporous polystyrene to ErCl3 solution and immerse it under magnetic stirring at room temperature for 12-24h to promote Er 3+ The loaded composite material is uniformly introduced into the ordered macroporous polystyrene pores, centrifuged, washed, dried, and collected for later use;

[0009] S2. The loaded composite material is evenly spread on a clean glass substrate and irradiated with a femtosecond laser for 20-30 min to stimulate an oxidation reaction of ErCl3 within the ordered macroporous polystyrene pores to form nanoscale erbium oxide crystals.

[0010] S3. Immerse the laser-treated sample in a sodium hydroxide solution and stir at room temperature for 2-3 hours to ensure that the ordered macroporous polystyrene is completely dissolved and decomposed. Centrifuge to separate the erbium oxide nanoparticles and wash them with deionized water until the washing solution is neutral. Place the washing solution in a vacuum drying oven and dry it for 12-15 hours to obtain the ultrafine erbium oxide nanomaterial.

[0011] Preferably, in step S1, the ordered macroporous polystyrene is prepared by the following steps:

[0012] S11. 350 nm SiO2 microspheres were dispersed in an ethanol-water mixture and self-assembled onto a clean glass substrate by deposition to form a compact and ordered three-dimensional template structure.

[0013] S12. A mixed monomer solution of styrene and divinylbenzene was prepared, with a crosslinking degree of 5-8%, and 0.5-1 wt% azobisisobutyronitrile was added. The assembled SiO2 template was immersed in the mixed monomer solution and vacuum impregnated for 5-10 h to ensure sufficient monomer penetration. The reaction was incubated at 70-80 ° C for 4-6 h to complete the free radical thermal polymerization of styrene to form a cross-linked polystyrene network to obtain a polymer / SiO2 composite material.

[0014] S13. Immerse the polymer / SiO2 composite material in a 2-3 wt% hydrofluoric acid aqueous solution, react at room temperature for 12-15 hours to etch away the SiO2 microsphere template, wash with deionized water until the washing solution is neutral to completely remove residual hydrofluoric acid and etching products, then wash with ethanol and vacuum dry at 60-80°C for 12-15 hours to obtain the ordered macroporous polystyrene.

[0015] Preferably, the solid-liquid ratio of the SiO2 template to the mixed monomer solution is 1:2-5.

[0016] Preferably, in step S1, the concentration of the ErCl3 solution is 0.05-0.1 mol / L.

[0017] Preferably, the solid-to-liquid ratio of the ordered macroporous polystyrene to the ErCl 3 solution is 1:5-10.

[0018] Preferably, the operating parameters of the femtosecond laser are set as follows: pulse width: 100-200 fs, wavelength: 400-600 nm, laser energy density: 0.5-1 mJ / cm 3 , pulse frequency: 0.5-1kHz.

[0019] Preferably, in step S3, the concentration of the sodium hydroxide solution is 0.5-1 mol / L.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses ordered macroporous polystyrene as a nanoreactor, uniformly introducing erbium salt into the pores by impregnation. Ultrafast laser excitation is then used to instantaneously oxidize the erbium salt to form nanoscale erbium oxide crystals. Finally, sodium hydroxide solution is used to gently remove the ordered macroporous polystyrene, resulting in high-purity erbium oxide nanopowders with uniform particle size.

[0022] 2. This method precisely controls particle size and crystallinity by adjusting laser parameters. The reaction process is rapid and efficient, avoiding traditional high-temperature and high-pressure conditions, making the process more environmentally friendly. Sodium hydroxide selectively dissolves the carrier without damaging the erbium oxide particles, ensuring the purity and stable performance of the material. The overall solution is simple to operate, combining advanced nanoreactor design and ultrafast laser technology, making it suitable for preparing erbium oxide nanomaterials with excellent performance and widespread applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a process flow chart for preparing the ultrafine erbium oxide nanomaterial of the present invention;

[0024] Figure 2 This is a flow chart of the preparation process of the ordered macroporous polystyrene of the present invention;

[0025] Figure 3 This is the XRD pattern of the ultrafine erbium oxide nanomaterial prepared in Example 1 of the present invention;

[0026] Figure 4These are SEM images of ultrafine erbium oxide nanomaterials of different sizes prepared in Example 1 of the present invention, including: (a) 5 μm size; (b) 2 μm size; (c) 1 μm size; (d) 500 nm size; (e) 200 nm size;

[0027] Figure 5 This is a BET specific surface area curve of the ultrafine erbium oxide nanomaterial described in Example 1 of the present invention;

[0028] Figure 6 This is a BET specific surface area curve of the ultrafine erbium oxide nanomaterial described in Example 2 of the present invention;

[0029] Figure 7 This is a BET specific surface area curve of the ultrafine erbium oxide nanomaterial described in Example 3 of the present invention;

[0030] Figure 8 This is a particle size distribution diagram of the ultrafine erbium oxide nanomaterial described in Example 1 of the present invention;

[0031] Figure 9 This is a particle size distribution diagram of the ultrafine erbium oxide nanomaterial described in Example 2 of the present invention;

[0032] Figure 10 This is a particle size distribution diagram of the ultrafine erbium oxide nanomaterial described in Example 3 of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] See also Figure 1-10 , the present invention provides a technical solution:

[0035] Example 1: This example provides a method for preparing ultrafine erbium oxide nanomaterials, comprising the following steps:

[0036] S1. Ordered macroporous polystyrene was added to a 0.05 mol / L ErCl3 solution at a solid-liquid ratio of 1:10 and immersed in a magnetic stirring solution (500 rpm) at room temperature for 12 h to promote the formation of Er. 3+ The loaded composite material was collected and stored for later use after centrifugation (8000 rpm, 5 min), washing, and drying (60 °C, 12 h).

[0037] S2. The loaded composite material was evenly spread on a clean glass substrate and a femtosecond laser (pulse width: 100 fs, wavelength: 500 nm, laser energy density: 0.5 mJ / cm 3 , pulse frequency: 1kHz) for 20 minutes, which stimulates the oxidation reaction of ErCl3 in the ordered macroporous polystyrene channels to form nano-scale erbium oxide crystals;

[0038] S3. The laser-treated sample was immersed in a 1 mol / L sodium hydroxide solution and stirred at room temperature for 2 h to ensure that the ordered macroporous polystyrene was completely dissolved and decomposed. The erbium oxide nanoparticles were separated by centrifugation and washed with deionized water until the washing solution was neutral. The washed solution was placed in a vacuum drying oven at 60°C for 12 h to obtain the ultrafine erbium oxide nanomaterial.

[0039] The ordered macroporous polystyrene is prepared by the following steps:

[0040] S11. 350 nm SiO2 microspheres were dispersed in an ethanol-water mixture and self-assembled onto a clean glass substrate by deposition to form a compact and ordered three-dimensional template structure.

[0041] S12. Prepare a mixed monomer solution of styrene and divinylbenzene with a crosslinking degree of 5%. Add 0.5 wt% azobisisobutyronitrile and immerse the assembled SiO2 template in the mixed monomer solution at a solid-to-liquid ratio of 1:3. Immerse the template in a vacuum (50 Pa) for 5 h to ensure full monomer penetration. Incubate at 70°C for 4 h to complete the free radical thermal polymerization of styrene and form a cross-linked polystyrene network, thereby producing a polymer / SiO2 composite.

[0042] S13. The polymer / SiO2 composite material is immersed in a 2 wt% hydrofluoric acid aqueous solution, reacted at room temperature for 12 hours to etch away the SiO2 microsphere template, washed with deionized water until the washing solution is neutral to completely remove residual hydrofluoric acid and etching products, then washed with ethanol and vacuum dried at 60°C for 12 hours to obtain the ordered macroporous polystyrene.

[0043] Example 2: This example provides a method for preparing ultrafine erbium oxide nanomaterials, comprising the following steps:

[0044] S1. Ordered macroporous polystyrene was added to a 0.05 mol / L ErCl3 solution at a solid-liquid ratio of 1:7 and immersed in a magnetic stirring solution (500 rpm) at room temperature for 15 h to promote the formation of Er. 3+ The loaded composite material was collected and stored for later use after centrifugation (8000 rpm, 5 min), washing, and drying (60 °C, 12 h).

[0045] S2. The loaded composite material was evenly spread on a clean glass substrate and a femtosecond laser (pulse width: 100 fs, wavelength: 500 nm, laser energy density: 0.75 mJ / cm 3 , pulse frequency: 1kHz) irradiation for 30 minutes stimulates the oxidation reaction of ErCl3 in the pores of ordered macroporous polystyrene to form nano-scale erbium oxide crystals;

[0046] S3. The laser-treated sample was immersed in a 1 mol / L sodium hydroxide solution and stirred at room temperature for 2.5 h to ensure that the ordered macroporous polystyrene was completely dissolved and decomposed. The erbium oxide nanoparticles were separated by centrifugation and washed with deionized water until the washing solution was neutral. The sample was then dried in a vacuum drying oven at 70°C for 12 h to obtain the ultrafine erbium oxide nanomaterial.

[0047] The ordered macroporous polystyrene is prepared by the following steps:

[0048] S11. 350 nm SiO2 microspheres were dispersed in an ethanol-water mixture and self-assembled onto a clean glass substrate by deposition to form a compact and ordered three-dimensional template structure.

[0049] S12. A mixed monomer solution of styrene and divinylbenzene was prepared with a crosslinking degree of 6%. 0.7 wt% azobisisobutyronitrile was added. The assembled SiO2 template was immersed in the mixed monomer solution at a solid-to-liquid ratio of 1:3. The mixture was immersed in a vacuum chamber (50 Pa) for 7 h to ensure full monomer penetration. The mixture was reacted at 70°C for 4 h to complete the free radical thermal polymerization of styrene and form a cross-linked polystyrene network, thereby producing a polymer / SiO2 composite material.

[0050] S13. The polymer / SiO2 composite material is immersed in a 2 wt% hydrofluoric acid aqueous solution, reacted at room temperature for 13 hours to etch away the SiO2 microsphere template, washed with deionized water until the washing solution is neutral to completely remove residual hydrofluoric acid and etching products, then washed with ethanol and vacuum dried at 70°C for 12 hours to obtain the ordered macroporous polystyrene.

[0051] Example 3: This example provides a method for preparing ultrafine erbium oxide nanomaterials, comprising the following steps:

[0052] S1. Ordered macroporous polystyrene was added to a 0.05 mol / L ErCl3 solution at a solid-liquid ratio of 1:5 and immersed for 15 h at room temperature under magnetic stirring (500 rpm) to promote Er 3+ The loaded composite material was collected and stored for later use after centrifugation (8000 rpm, 5 min), washing, and drying (60 °C, 12 h).

[0053] S2. The loaded composite material was evenly spread on a clean glass substrate and laser-assisted by a femtosecond laser (pulse width: 100 fs, wavelength: 500 nm, laser energy density: 1 mJ / cm 3 , pulse frequency: 1kHz) irradiation for 30 minutes stimulates the oxidation reaction of ErCl3 in the pores of ordered macroporous polystyrene to form nano-scale erbium oxide crystals;

[0054] S3. The laser-treated sample was immersed in a 1 mol / L sodium hydroxide solution and stirred at room temperature for 2.5 h to ensure that the ordered macroporous polystyrene was completely dissolved and decomposed. The erbium oxide nanoparticles were separated by centrifugation and washed with deionized water until the washing solution was neutral. The sample was then dried in a vacuum drying oven at 80°C for 12 h to obtain the ultrafine erbium oxide nanomaterial.

[0055] The ordered macroporous polystyrene is prepared by the following steps:

[0056] S11. 350 nm SiO2 microspheres were dispersed in an ethanol-water mixture and self-assembled onto a clean glass substrate by deposition to form a compact and ordered three-dimensional template structure.

[0057] S12. A mixed monomer solution of styrene and divinylbenzene was prepared with a crosslinking degree of 8%. 1 wt% azobisisobutyronitrile was added. The assembled SiO2 template was immersed in the mixed monomer solution at a solid-to-liquid ratio of 1:4. The mixture was immersed in a vacuum chamber (50 Pa) for 8 h to ensure full monomer penetration. The mixture was reacted at 70°C for 4 h to complete the free radical thermal polymerization of styrene and form a cross-linked polystyrene network, thereby producing a polymer / SiO2 composite material.

[0058] S13. The polymer / SiO2 composite material is immersed in a 2 wt% hydrofluoric acid aqueous solution and reacted at room temperature for 14 hours to etch away the SiO2 microsphere template, and then washed with deionized water until the washing solution is neutral to completely remove the residual hydrofluoric acid and etching products, followed by washing with ethanol and vacuum drying at 70°C for 12 hours to obtain the ordered macroporous polystyrene.

[0059] Performance test, the ICP test data of the ultrafine erbium oxide nanomaterials prepared in Examples 1-3 of the present invention are as follows:

[0060]

[0061] From the ICP test data of Examples 1-3, it can be seen that the ultrafine erbium oxide nanomaterial prepared by the present invention contains almost no additional rare earth elements and has extremely high purity;

[0062] The XRD pattern of the ultrafine erbium oxide nanomaterial prepared in Example 1 of the present invention is as follows: Figure 3 As shown in the figure, multiple distinct and sharp diffraction peaks appear, indicating that the sample has a good crystal structure and high crystallinity. The peak positions are highly consistent with the reference Er2O3 standard diffraction data (JCPDS card number 00-024-0521), indicating that the sample is primarily composed of cubic Er2O3. There are no obvious impurity peaks or diffraction signals from other phases, further demonstrating the extremely high purity and good crystallinity of the erbium oxide material prepared by this invention.

[0063] The SEM images of the ultrafine erbium oxide nanomaterials of different sizes prepared in Example 1 are as follows: Figure 4 As shown:

[0064] in, Figure 4 a and 4b are low-magnification images, showing that erbium oxide nanoparticles are distributed on the substrate in the form of agglomerates. The particle distribution is relatively uniform, and there are no obvious large agglomerates. This shows that the preparation method helps to obtain relatively dispersed nanoparticles. The size of the particle agglomerates is approximately in the range of several microns, indicating that the nanoparticles have a certain degree of aggregation during the drying process, but the overall agglomerate morphology is relatively loose, which is conducive to dispersion in subsequent applications.

[0065] Figure 4 Images c-4e show medium and high magnifications, showing a clearer view of the particle morphology. The erbium oxide particles are composed of numerous nanoparticles approximately tens of nanometers in size, with distinct nanoscale pores and a rough surface structure. The particle surface exhibits granular accumulation, indicating that the femtosecond laser-induced oxidation reaction produced nanocrystals. After sodium hydroxide dissolved the macroporous polystyrene template, the nanoparticles retained their well-defined morphology and three-dimensional porous structure.

[0066] Figure 5-7 This is a BET specific surface area curve of the ultrafine erbium oxide nanomaterials described in Examples 1-3 of the present invention. As shown in the figure, the specific surface areas of Examples 1-3 can be obtained as follows:

[0067]

[0068] The difference in specific surface area between Examples 1 and 3 is primarily due to the fact that Example 1 employed a solid-to-liquid ratio of 1:10, an immersion time of 12 hours, a laser energy density of 0.5 mJ / cm³, a crosslinking degree of 5%, and an azobisisobutyronitrile dosage of 0.5 wt %. The template immersion time was short and the crosslinking degree was low. These factors collectively facilitated the more uniform and sufficient entry of Er³⁺ ions into the template pores, and the template's low crosslinking degree made the polymer network softer, facilitating the penetration and uniform distribution of monomers and precursors. Lower laser energy and shorter irradiation times facilitated the formation of small, well-dispersed nanocrystals, avoiding excessive particle size growth. As a result, the final erbium oxide nanomaterial possessed a higher specific surface area and exhibited optimal nanoporous structural characteristics.

[0069] In contrast, in Example 2, the laser energy density was increased to 0.75 mJ / cm³, the degree of crosslinking was increased to 6%, and the amount of azobisisobutyronitrile was increased to 0.7 wt%. The increase in laser energy density and the higher degree of crosslinking made the polymer network structure more compact, the monomer permeability was relatively reduced, and the laser irradiation time was also extended to 30 minutes, which may cause partial agglomeration of the nanocrystals and increase in particle size, resulting in a decrease in specific surface area. Therefore, the specific surface area of ​​Example 2 was reduced compared to Example 1, but still remained at a high level, indicating that the material maintained a good nanostructure.

[0070] In Example 3, the laser energy density was increased to 1 mJ / cm³, the crosslinking degree was raised to 8%, the amount of azobisisobutyronitrile was increased to 1 wt%, and the drying temperature was raised to 80°C. The higher crosslinking degree resulted in a tighter polymer template network, restricting further penetration of the monomer and Er³⁺. Further increases in laser energy density and longer treatment times triggered excessive growth and aggregation of erbium oxide nanoparticles, increasing their size and significantly reducing their specific surface area. Furthermore, higher drying temperatures may have caused some nanoparticles to sinter or agglomerate, further reducing the specific surface area.

[0071] Figure 8-10 The particle size distribution diagram of the ultrafine erbium oxide nanomaterial prepared in Examples 1-3 of the present invention is shown in the figure. The D10, D25, D50, D75, D90, and D99 of Examples 1-3 can be obtained as follows:

[0072]

[0073] As can be seen from the above, the D10 value gradually increases from 0.065 μm in Example 1 to 0.079 μm in Example 3, indicating that the minimum particle size range has increased and the fineness of the nanoparticles has decreased. The D25 and D50 values ​​also show an upward trend, increasing from 0.089 μm and 0.132 μm to 0.120 μm and 0.214 μm, respectively. This indicates that approximately 25% and 50% of the particles in the sample have significantly increased in size, and the particle distribution has shifted to a larger size range. For the D90 and D99 values, the values ​​for Example 1 are 0.349 μm and 0.951 μm, respectively, and Example 2 increases significantly to 0.705 μm and 2.212 μm, while the D90 of Example 3 reaches 2.759 μm, showing a wider particle size distribution and the presence of larger particle agglomerates.

[0074] The reason for this is speculated to be that Example 1 uses a lower laser energy density, a longer immersion time, and a lower polymer cross-linking degree, which helps the Er³⁺ ions to be evenly distributed within the template pores and form relatively small and dispersed nanocrystals, resulting in a smaller particle size and a narrower distribution, and milder particle agglomeration. In Example 2, the laser energy density is increased to 0.75 mJ / cm³, the immersion time is prolonged, and the cross-linking degree is increased to 6%, resulting in a denser template structure and more intense laser treatment, which promotes partial agglomeration of the nanocrystals and a significant increase in particle size, especially in the large particle size portion (D90, D99). This indicates that the aggregation and agglomeration between nanoparticles has intensified. In Example 3, the laser energy density is increased to 1.0 mJ / cm³, the cross-linking degree reaches 8%, and the laser irradiation time is prolonged, resulting in more obvious growth and agglomeration of the nanoparticles. Particle size data show that Example 3 has the widest particle distribution, with a median diameter (D50) of 0.214 μm, a D75 of 1.191 μm, and a D90 of 2.759 μm, significantly larger than the previous two examples. This indicates the presence of a large number of large particle agglomerates, resulting in reduced particle uniformity and fineness. The high degree of cross-linking and laser energy density may have caused template pore shrinkage and high energy aggregation between nanoparticles, promoting particle agglomeration and sintering.

[0075] At the same time, the D10 values ​​of the various examples are all in the range of 0.065-0.079 μm, indicating that the three preparation conditions can all generate a certain proportion of ultrafine particles.

[0076] The above content strongly proves that the preparation method provided by the present invention can avoid the complex reaction steps in traditional chemical synthesis and realize the preparation of nano-erbium oxide with controllable particle size and uniform morphology. Moreover, the process is green and environmentally friendly, the equipment is simple and easy to use, and it is suitable for large-scale production.

[0077] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing ultrafine erbium oxide nanomaterials, characterized in that: The following steps are involved: S1. Add ordered macroporous polystyrene to ErCl3 solution and immerse it under magnetic stirring at room temperature for 12-24h to promote Er 3+ The loaded composite material is uniformly introduced into the ordered macroporous polystyrene pores, centrifuged, washed, dried, and collected for later use; S2. The loaded composite material is evenly spread on a clean glass substrate and irradiated with a femtosecond laser for 20-30 min to stimulate an oxidation reaction of ErCl3 within the ordered macroporous polystyrene pores to form nanoscale erbium oxide crystals. S3. Immerse the laser-treated sample in a sodium hydroxide solution and stir at room temperature for 2-3 hours to ensure that the ordered macroporous polystyrene is completely dissolved and decomposed. Centrifuge to separate the erbium oxide nanoparticles and wash them with deionized water until the washing solution is neutral. Place the washing solution in a vacuum drying oven and dry it for 12-15 hours to obtain the ultrafine erbium oxide nanomaterial.

2. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 1, wherein: In step S1, the ordered macroporous polystyrene is prepared by the following steps: S11. 350 nm SiO2 microspheres were dispersed in an ethanol-water mixture and self-assembled onto a clean glass substrate by deposition to form a compact and ordered three-dimensional template structure. S12. A mixed monomer solution of styrene and divinylbenzene was prepared with a crosslinking degree of 5-8%. 0.5-1 wt% azobisisobutyronitrile was added. The assembled SiO2 template was immersed in the mixed monomer solution and vacuum impregnated for 5-10 h to ensure sufficient monomer penetration. The mixture was reacted at 70-80 ° C for 4-6 h to complete the free radical thermal polymerization of styrene to form a cross-linked polystyrene network to obtain a polymer / SiO2 composite material. S13. Immerse the polymer / SiO2 composite material in a 2-3 wt% hydrofluoric acid aqueous solution, react at room temperature for 12-15 hours to etch away the SiO2 microsphere template, wash with deionized water until the washing solution is neutral to completely remove residual hydrofluoric acid and etching products, then wash with ethanol and vacuum dry at 60-80°C for 12-15 hours to obtain the ordered macroporous polystyrene.

3. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 2, wherein: The solid-to-liquid ratio of the SiO2 template to the mixed monomer solution is 1:2-5.

4. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 3, wherein: In step S1, the concentration of the ErCl3 solution is 0.05-0.1 mol / L.

5. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 4, wherein: The solid-to-liquid ratio of the ordered macroporous polystyrene to the ErCl3 solution is 1:5-10.

6. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 1, wherein: The operating parameters of the femtosecond laser are set as follows: pulse width: 100-200 fs, wavelength: 400-600 nm, laser energy density: 0.5-1 mJ / cm 3 , pulse frequency: 0.5-1kHz.

7. The method for preparing an ultrafine erbium oxide nanomaterial according to claim 1, characterized in that: In step S3, the concentration of the sodium hydroxide solution is 0.5-1 mol / L.

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