A method and device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser

Abstract

The present invention provides a method and device for preparing ultrafine magnetic nanoparticles by using a magnetic field-assisted laser, and relates to the technical field of magnetic nanomaterials. The method comprises: S1, using laser to ablate micron-sized magnetic raw material powder to produce a sputtered melt; S2, using an inert gas to purge the sputtered melt while performing laser ablation to produce magnetic material powder; S3, using an inert gas carrier gas to pass the magnetic material powder through a set magnetic auxiliary field, and screening to obtain ultrafine magnetic nanoparticles; S4, collecting the ultrafine magnetic nanoparticles at a set position, washing, and then drying. The present invention uses high-energy pulsed laser to ablate large-sized magnetic raw materials. Under the action of the inert gas and the set magnetic auxiliary field, no impurities common in chemical synthesis methods are produced, and the crystallinity is high and the particle size distribution range is narrow.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic nanomaterials, and in particular to a method and device for preparing ultrafine magnetic nanoparticles with magnetic field-assisted laser. Background Art

[0002] Ultrafine magnetic nanoparticles, owing to their unique magnetic properties, have found widespread application in biomedical fields. Ultrafine magnetic nanoparticles not only generate magnetic, thermal, and mechanical effects mediated by external fields but also possess nanozyme catalytic activity. Therefore, they hold great promise for applications in biomedical fields such as magnetic resonance imaging, cell fate regulation, magnetic hyperthermia for tumors, brain neurostimulation, and controlled drug delivery. Common medical ultrafine magnetic nanoparticles include iron oxide nanoparticles and magnetic metal nanoparticles (iron, cobalt, and nickel).

[0003] Currently, the main methods for preparing ultrafine magnetic nanoparticles are chemical synthesis, including hydrothermal, solvothermal, high-temperature thermal decomposition, coprecipitation, microemulsion, and ultrasonic irradiation. These methods involve complex chemical reactions, typically involving the nucleation and growth of inorganic or organic iron-containing compounds in solution through hydrolysis, condensation, and thermal decomposition. These complex chemical synthesis methods result in nanoparticles with wide particle size distributions, low crystallinity, and numerous impurities. Furthermore, some chemical synthesis methods involve toxic organic reagents, resulting in high costs. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method and device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser. Nanoparticles are prepared by laser ablation, and the magnetic auxiliary field is added to regulate the motion state of the nanoparticles, so as to concentrate and collect nanoparticles of a specific size.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, a method for preparing ultrafine magnetic nanoparticles by laser assisted magnetic field comprises the following steps:

[0007] S1. Using laser to ablate micron-sized magnetic raw material powder to generate sputtering melt;

[0008] S2, while laser ablation is being performed, an inert gas is used to purge the sputtered melt to produce magnetic material powder;

[0009] S3, using an inert gas carrier gas to pass the magnetic material powder through a set magnetic auxiliary field to screen ultrafine magnetic nanoparticles;

[0010] S4. Collecting the ultrafine magnetic nanoparticles at a set location, washing them and then drying them.

[0011] In the second aspect, ultrafine magnetic nanoparticles are prepared by the above-mentioned method of preparing ultrafine magnetic nanoparticles with magnetic field-assisted laser.

[0012] Optionally, the ultrafine magnetic nanoparticles refer to magnetic nanoparticles with a particle size ranging from 10 to 20 nm.

[0013] In a third aspect, an apparatus for implementing the above-mentioned method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser light ...

[0014] The air inlet is connected to an air inlet device, and the air inlet device is used to introduce an inert gas with a set flow rate into the quartz tube;

[0015] A laser for ablating magnetic raw material powder in a quartz tube;

[0016] An electromagnetic coil, the electromagnetic coil being used to generate a magnetic field of set strength and direction in the quartz tube;

[0017] The collecting device is installed at the air outlet of the quartz tube and is used to collect the prepared ultrafine magnetic nanoparticles.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. This method uses high-energy pulsed lasers to ablate large-scale magnetic raw materials. Using an inert gas and a controlled magnetic assist field, the sputtered melt is swept and collected to produce ultrafine magnetic nanoparticles with a particle size of 10-20 nm. This method eliminates the impurities commonly found in chemical synthesis methods, achieves high crystallinity, and exhibits a narrow particle size distribution. The method is simple, cost-effective, and rapid, and does not involve the use of toxic organic reagents, making it suitable for large-scale production.

[0020] 2. The ultrafine magnetic nanoparticles prepared by the present invention have uniform particle size distribution and are suitable for use in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0023] Figure 1 Schematic diagram of the device for preparing ultrafine magnetic nanoparticles using magnetic field-assisted laser in Example 1.

[0024] Figure 2This is the TEM image in Example 2.

[0025] Figure 3 This is the XRD test result in Example 2.

[0026] Figure 4 This is the Raman spectrum detection result in Example 2.

[0027] Figure 5 This is the TEM image in Example 3.

[0028] Figure 6 This is the XRD test result in Example 3.

[0029] Figure 7 This is the Raman spectrum detection result in Example 3.

[0030] Among them, 1. Quartz tube; 2. Porcelain boat; 3. Air inlet; 4. Air outlet; 5. Electromagnetic coil; 6. Laser; 7. Laser; 8. Collection device. DETAILED DESCRIPTION

[0031] A method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser, comprising the following steps:

[0032] S1. Using laser to ablate micron-sized magnetic raw material powder to generate sputtering melt;

[0033] S2, while laser ablation is being performed, an inert gas is used to purge the sputtered melt to produce magnetic material powder;

[0034] S3, using an inert gas carrier gas to pass the magnetic material powder through a set magnetic auxiliary field to screen and obtain ultrafine magnetic nanoparticles;

[0035] S4. Collect ultrafine magnetic nanoparticles at a set location, wash them, and then dry them.

[0036] Optionally, in S1, the particle size of the magnetic raw material powder is 10-100 μm.

[0037] Optionally, in S1, the material of the magnetic raw material powder includes: metallic magnetic material or non-metallic magnetic material;

[0038] Metal magnetic materials include: neodymium iron boron alloy or cobalt alloy or nickel iron alloy;

[0039] The non-metallic magnetic material includes: ferrite magnetic material or magnetic ceramic; preferably, it includes ferrosoferric oxide.

[0040] Optionally, in S1, the laser wavelength is 355~1064 nm.

[0041] Optionally, in S1, the laser is a pulsed laser with a pulse width of 0.4 to 20 ns.

[0042] Optionally, in S1, the laser power density is 0.5~15.0 J / cm 2 , the ablation time is 10~60 min.

[0043] Optionally, in S2, the inert gas includes high-purity argon, and the purge rate is 50-350 mL / min.

[0044] Optionally, in S3, the magnetic field strength is 10-50 mT, and the direction of the magnetic field is parallel to the carrier gas flow direction.

[0045] Optionally, in S4, the drying method is vacuum drying, and the vacuum drying time is 8 to 16 hours.

[0046] Ultrafine magnetic nanoparticles prepared by the method for preparing ultrafine magnetic nanoparticles with magnetic field-assisted laser.

[0047] Optionally, the ultrafine magnetic nanoparticles refer to magnetic nanoparticles with a particle size ranging from 10 to 20 nm.

[0048] Optionally, the particle size of the prepared ferroferric oxide ultrafine magnetic nanoparticles is 10-20 nm.

[0049] Optionally, the particle size of the prepared NdFeB ultrafine magnetic nanoparticles is 10-20 nm.

[0050] The device for implementing the above-mentioned method of preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser comprises: a quartz tube, an air inlet and an air outlet are respectively provided at both ends of the quartz tube, and the quartz tube is loaded with magnetic raw material powder;

[0051] The air inlet is connected to an air inlet device, which is used to introduce an inert gas with a set flow rate into the quartz tube;

[0052] Laser, which is used to ablate magnetic raw material powder in a quartz tube;

[0053] A magnetic field assist device, which is used to generate a magnetic field of set strength and direction in the quartz tube;

[0054] The collecting device is installed at the air outlet of the quartz tube and is used to collect the prepared ultrafine magnetic nanoparticles.

[0055] Optionally, a porcelain boat is provided in the quartz tube, and the porcelain boat is loaded with magnetic raw material powder.

[0056] Optionally, the inert gas introduced into the gas inlet device includes: high-purity argon.

[0057] Optionally, the purge rate of the air inlet device is 50~350 mL / min.

[0058] Optional laser with a wavelength of 355-1064 nm, a pulse width of 0.4-20 ns, and a laser power density of 0.5-15.0 J / cm 2 .

[0059] Optionally, the magnetic field auxiliary device is an electromagnetic coil, which is wound around the outside of the quartz tube. The magnetic field strength generated in the quartz tube is 10~50 mT, and the direction of the magnetic field is parallel to the airflow direction.

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0061] Example 1:

[0062] like Figure 1 As shown, a device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser comprises: a quartz tube 1, an air inlet 3 and an air outlet 4 are respectively provided at both ends of the quartz tube 1, and magnetic raw material powder is loaded in the quartz tube 1;

[0063] The air inlet 3 is connected to an air inlet device, which is used to introduce an inert gas with a set flow rate into the quartz tube 1;

[0064] Laser 6, laser 6 is used to generate laser light 7, laser light 7 is irradiated on the magnetic raw material powder to produce ablation effect, thereby producing a sputtering melt of the magnetic raw material powder;

[0065] The electromagnetic coil 5 is arranged between the porcelain boat 2 and the air outlet 4 and is used to generate a magnetic field of set strength and direction in the quartz tube 1;

[0066] A collecting device 8 is installed at the air outlet 4 of the quartz tube 1 and is used to collect the prepared ultrafine magnetic nanoparticles;

[0067] Optionally, the collecting device 8 is disposed on the other side of the electromagnetic coil 5 relative to the magnetic raw material powder, and the distance from the electromagnetic coil 5 can be adjusted, preferably, the adjustment range is 5 to 30 cm.

[0068] Optionally, the collecting device 8 is made of filter paper, and the adsorption capacity of the filter paper fibers is used to capture the nanoparticles in the carrier gas.

[0069] Optionally, a porcelain boat 2 is provided in the quartz tube 1 , and the porcelain boat 2 is loaded with magnetic raw material powder. Preferably, the porcelain boat 2 is a silicon carbide porcelain boat.

[0070] Optionally, the inert gas introduced into the gas inlet device includes: high-purity argon.

[0071] Optionally, the inner diameter of the quartz tube 1 is 5-10 cm, and the purge speed of the gas inlet device is 50-350 mL / min.

[0072] Optionally, the laser wavelength of the laser 6 is 355-1064 nm, the pulse width is 0.4-20 ns, and the laser power density is 0.5-15.0 J / cm 2 .

[0073] Optionally, the electromagnetic coil 5 is wound around the outside of the quartz tube 1 , and the magnetic field strength generated in the quartz tube 1 is 10-50 mT, and the direction of the magnetic field is parallel to the direction of the airflow.

[0074] In the device, since the airflow and magnetic field exert different forces on nanoparticles of different sizes, the movement speed and sedimentation position of nanoparticles of different sizes can be different by adjusting the airflow and magnetic field strength: at positions from near to far away from the laser beam, the collected particles tend to be distributed from large to small.

[0075] Therefore, by setting the collecting device 8 at a specific position, nanoparticles of different particle size ranges can be collected: at a close position, nanoparticles with a wide size range from large to small can be collected; at a far position, nanoparticles with a smaller particle size and a narrower particle size range can be collected.

[0076] Example 2

[0077] A method for preparing ferrosoferric oxide nanoparticles using the device in Example 1 comprises the following steps:

[0078] Step 1: Place ferroferric oxide particles with a particle size of 45 μm in a silicon carbide porcelain boat, compact it to obtain a flat upper surface, and place the porcelain boat containing the ferroferric oxide particles in a transparent quartz tube;

[0079] Step 2: Use a nanosecond pulsed laser with a wavelength of 532 nm to ablate the flat upper surface of the ferroferric oxide powder in the porcelain boat. The laser power density is 5 J / cm 2 , the processing area is 1 cm 2 , processing time is 30 min;

[0080] Step 3: During the laser ablation process, high-purity argon gas was introduced into the transparent quartz tube at a flow rate of 100 mL / min;

[0081] Step 4: During the laser ablation process, the electromagnetic coil is energized so that the magnetic field strength in the transparent quartz tube is 25 mT;

[0082] Step 5: Place a folded multi-layer filter paper at the outlet of the quartz tube to collect the solid product flowing out of the transparent quartz tube with the carrier gas. At this time, the outlet is located at the left end of the quartz tube, the inlet is located at the right end of the quartz tube, the right end of the electromagnetic coil is close to the laser ablation position, the length of the electromagnetic coil winding outside the quartz tube is 20 cm, and the distance between the filter paper and the left end of the electromagnetic coil is 5 cm;

[0083] Step 6: Place the filter paper containing the solid product collected in step 5 in anhydrous ethanol and ultrasonically vibrate for 10 minutes to obtain a nanoparticle suspension of ferrosoferric oxide.

[0084] Step 7: The obtained ferroferric oxide nanoparticle suspension is subjected to solid-liquid separation by centrifugation, and then vacuum dried for 10 h to obtain ferroferric oxide ultrafine magnetic nanoparticles.

[0085] During this process, the surface of the micron-sized Fe3O4 particle powder absorbs the irradiation energy of the high-energy laser, causing the temperature to rise sharply, reaching a melting and vaporization state in a short period of time. The steam recoil pressure can sputter part of the melt to form nanoparticles.

[0086] The magnetic field exerts different forces on nanoparticles of different sizes. By adjusting the strength of the magnetic field, the particle sizes collected are distributed from large to small at positions from near to far away from the laser beam.

[0087] The obtained ultrafine magnetic nanoparticles of ferroferric oxide were observed by TEM, and the images obtained were as follows: Figure 2 As shown, it can be seen that the particle size of the ferroferric oxide nanoparticles is in the range of 10-20 nm, and the particle size distribution is uniform. Since the nanoparticles will spontaneously agglomerate, the figure shows a state of aggregation of multiple nanoparticles.

[0088] The obtained ultrafine magnetic nanoparticles of ferroferric oxide were subjected to XRD test. The test results are as follows: Figure 3 As shown, it can be seen that the composition of the ultrafine magnetic nanoparticles of ferroferric oxide obtained in this example is consistent with the Fe3O4 phase, and its diffraction peak has a high diffraction intensity and a sharp peak shape, indicating that the obtained ultrafine magnetic nanoparticles of ferroferric oxide have a high degree of crystallinity.

[0089] The obtained ultrafine magnetic nanoparticles of ferroferric oxide were subjected to Raman spectroscopy detection, and the detection results were as follows: Figure 4 As shown in Figure 2, four obvious characteristic peaks can be observed, at 225, 364, 532, and 668 cm -1 The position is consistent with the typical Raman spectral characteristics of Fe3O4 nanocrystals.

[0090] The ultrafine magnetic nanoparticles of ferroferric oxide prepared in this embodiment have the characteristics of narrow particle size distribution range and single composition.

[0091] The obtained ultrafine magnetic nanoparticles of ferroferric oxide meet the use standards of inorganic nanomaterials approved by the U.S. Food and Drug Administration (FDA) for clinical use and can be used in the biomedical field.

[0092] Example 3

[0093] A method for preparing NdFeB ultrafine magnetic nanoparticles using the apparatus of Example 1 comprises the following steps:

[0094] Step 1: Place NdFeB magnetic particle powder with a particle size of 50 μm in a silicon carbide porcelain boat, compact it to obtain a flat upper surface, and place the porcelain boat containing the NdFeB magnetic particle powder in a transparent quartz tube;

[0095] Step 2: Use a nanosecond pulsed laser with a wavelength of 1064 nm to ablate the flat upper surface of the ferroferric oxide powder in the porcelain boat. The laser power density is 5 J / cm 2 , the processing area is 1 cm 2 , processing time is 30 min;

[0096] Step 3: During the laser ablation process, high-purity argon gas was introduced into the transparent quartz tube at a flow rate of 100 mL / min;

[0097] Step 4: During the laser ablation process, the electromagnetic coil is energized so that the magnetic field strength in the transparent quartz tube is 35 mT;

[0098] Step 5: Place a folded multi-layer filter paper at the outlet of the quartz tube to collect the solid product flowing out of the transparent quartz tube with the carrier gas. At this time, the outlet is located at the left end of the quartz tube, the inlet is located at the right end of the quartz tube, the right end of the electromagnetic coil is close to the laser ablation position, the length of the electromagnetic coil winding outside the quartz tube is 25 cm, and the distance between the filter paper and the left end of the electromagnetic coil is 5 cm;

[0099] Step 6: Place the filter paper containing the solid product collected in step 5 in anhydrous ethanol and ultrasonically vibrate for 8 minutes to obtain a suspension of NdFeB nanoparticles.

[0100] Step 7: The obtained ferroferric oxide nanoparticle suspension is centrifuged, solid-liquid separated, and then vacuum dried for 12 hours to obtain NdFeB ultrafine magnetic nanoparticles.

[0101] The obtained NdFeB ultrafine magnetic nanoparticles were observed by TEM, and the images obtained are as follows Figure 5 As shown, it can be seen that the particle size of NdFeB ultrafine magnetic nanoparticles is in the range of 10-20 nm, and the particle size distribution is uniform;

[0102] Since nanoparticles will spontaneously agglomerate, the picture shows the state of multiple particles aggregated.

[0103] The obtained NdFeB ultrafine magnetic nanoparticles were subjected to XRD detection, and the test results were as follows: Figure 6 As shown in the figure, it can be seen that the composition of the NdFeB ultrafine magnetic nanoparticles obtained in this embodiment conforms to the Nd2Fe 14 The diffraction peak of phase B has a high diffraction intensity and a sharp peak shape, indicating that the obtained NdFeB ultrafine magnetic nanoparticles have a high degree of crystallinity.

[0104] The obtained NdFeB ultrafine magnetic nanoparticles were subjected to Raman spectroscopy detection, and the detection results were as follows: Figure 7 As shown, it can be observed that the test results are consistent with Nd2Fe 14 Typical Raman spectral characteristics of B nanocrystals.

[0105] Therefore, the NdFeB ultrafine magnetic nanoparticles prepared in this embodiment have the characteristics of narrow particle size distribution range and single composition, and can be applied in the biomedical field.

[0106] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing ultrafine magnetic nanoparticles by laser assisted magnetic field, characterized in that the steps include: S1. Using laser to ablate micron-sized magnetic raw material powder to generate sputtering melt; S2, while laser ablation is being performed, an inert gas is used to purge the sputtered melt to produce magnetic material powder; S3, using an inert gas carrier gas to pass the magnetic material powder through a set magnetic auxiliary field to screen and obtain ultrafine magnetic nanoparticles; S4, collecting the ultrafine magnetic nanoparticles at a set location, washing and drying; In S1, the particle size of the magnetic raw material powder is 10-100 μm; the laser is a pulsed laser with a pulse width of 0.4-20 ns; and the power density of the laser is 0.5-15.0 J / cm 2 , ablation time is 10~60 min; The ultrafine magnetic nanoparticles refer to magnetic nanoparticles with a particle size range of 10 to 20 nm; In S2, the purge rate was 50–350 mL / min; In S3, the magnetic field strength is 10–50 mT; the magnetic field direction is parallel to the carrier gas flow direction; In S4, the distance between the location where ultrafine magnetic nanoparticles are collected and the magnetic assisting field is adjusted in the range of 5–30 cm.

2. The method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 1, characterized in that: In S1, the material of the magnetic raw material powder includes: metallic magnetic material or non-metallic magnetic material; Metal magnetic materials include: neodymium iron boron alloy or cobalt alloy or nickel iron alloy; Non-metallic magnetic materials include: ferrite magnetic materials.

3. The method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 2, characterized in that: In S1, the non-metallic magnetic material includes ferrosoferric oxide.

4. The method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 1, wherein: Inert gases include high purity argon.

5. Ultrafine magnetic nanoparticles prepared by the method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 1 or 4, characterized in that: The particle size of the prepared ferroferric oxide ultrafine magnetic nanoparticles is 10-20 nm; Alternatively, the particle size of the prepared NdFeB ultrafine magnetic nanoparticles is 10-20 nm.

6. A device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser for implementing the method for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to any one of claims 1 to 4, characterized in that: include: A quartz tube, wherein both ends of the quartz tube are respectively provided with an air inlet and an air outlet, and the quartz tube is loaded with magnetic raw material powder; The air inlet is connected to an air inlet device, and the air inlet device is used to introduce an inert gas with a set flow rate into the quartz tube; A laser for ablating magnetic raw material powder in a quartz tube; An electromagnetic coil, the electromagnetic coil being used to generate a magnetic field of set strength and direction in the quartz tube; The collecting device is installed at the air outlet of the quartz tube and is used to collect the prepared ultrafine magnetic nanoparticles.

7. The device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 6, characterized in that: A porcelain boat is arranged in the quartz tube, and magnetic raw material powder is loaded in the porcelain boat.

8. The device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 6, characterized in that: The collecting device is arranged on the other side of the electromagnetic coil relative to the magnetic raw material powder, and the distance from the electromagnetic coil is adjustable.

9. The device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 8, characterized in that: Filter paper is used as the collection device.

10. The device for preparing ultrafine magnetic nanoparticles by magnetic field-assisted laser according to claim 8, characterized in that: The distance between the collecting device and the electromagnetic coil can be adjusted in the range of 5 to 30 cm.

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