Preparation method of FeCo hard magnetic nanowire

Abstract

The invention provides a FeCo hard magnetic nanowire preparation method, which comprises: mixing an iron source, a cobalt source, a reducing agent and a solvent, heating to a temperature of 70-75 DEG C in an argon atmosphere, carrying out ultrasonic treatment for 12-17 min, dehydrating at a temperature of 110-120 DEG C, adding a surfactant, continuously heating to a reaction temperature, carrying out heat preservation, and applying a static micro-magnetic field during the heat preservation to obtain a reaction product; and purifying the reaction product to obtain the FeCo hard magnetic nanowire. The invention provides a magnetic field-surfactant synergistically assisted wet chemical method, which is used for synthesizing bct-FeCo nanowires. According to the method, the single-phase hard magnetic bct-FeCo ordered nanometer one-dimensional structure is successfully prepared by synergistically utilizing crystal lattice stress induced by a surfactant ligand and a magnetic field orientation effect. The FeCo hard magnetic nanowire has relatively high coercive force.

Description

Technical Field

[0001] This invention belongs to the field of nanowire preparation technology, and particularly relates to a method for preparing FeCo hard magnetic nanowires. Background Technology

[0002] FeCo alloys possess extremely high saturation magnetization (Ms ≈ 245 emu / g) and ultra-high Curie temperature (Tc ≈ 980℃), showing significant application potential in cutting-edge fields such as high-density magnetic storage, microwave absorption, biomedicine, and high-temperature magnetic devices. However, FeCo alloys prepared by conventional methods have Fe and Co atoms arranged randomly, exhibiting a body-centered cubic (bcc) structure, and their intrinsic coercivity is low, classifying them as typical soft magnetic materials.

[0003] FeCo alloys can form an ordered structure with alternating Fe and Co atoms, a body-centered tetragonal (bct) structure. This structure effectively improves its uniaxial magnetocrystalline anisotropy, thus yielding FeCo alloys with hard magnetic properties. Theoretically, transforming FeCo into an ordered bct structure can achieve a uniaxial magnetocrystalline anisotropy constant (Ku) as high as 10 MJ / m³, thereby significantly improving coercivity and exhibiting high hard magnetic properties, making it a potential candidate system for rare-earth-free permanent magnet materials with significant application prospects. According to Bain crystallographic correspondences, the bct structure is a metastable transition phase between the bcc and fcc structures, making its synthesis difficult. Therefore, the preparation of FeCo hard magnetic nanomaterials with high magnetocrystalline anisotropy has always been a bottleneck problem in this field. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing FeCo hard magnetic nanowires, which uses a wet chemical method to directly prepare FeCo hard magnetic nanowires with high coercivity.

[0005] This invention provides a method for preparing FeCo hard magnetic nanowires, comprising the following steps:

[0006] Iron source, cobalt source, reducing agent and solvent are mixed, heated to 70~75℃ under argon atmosphere, ultrasonically treated for 12~17min, dehydrated at 110~120℃, surfactant is added, and the temperature is further raised to the reaction temperature. The temperature is maintained and a static micro-magnetic field is applied during the holding period to obtain the reaction product.

[0007] The reaction product was purified to obtain FeCo hard magnetic nanowires.

[0008] Preferably, the iron source is selected from one or more of ferric acetylacetone, ferric chloride, ferric sulfide, and ferric nitrate;

[0009] The cobalt source is selected from one or more of cobalt acetylacetonate, cobalt chloride, cobalt sulfide, and cobalt nitrate;

[0010] The surfactant is selected from one or more of oleylamine, oleic acid, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride;

[0011] The solvent is selected from one or more of dodecylamine, octadecamine, hexadecamine, and trioctylamine.

[0012] Preferably, the molar ratio of iron in the iron source to cobalt in the cobalt source is (0.25~5):1;

[0013] The amount of the reducing agent used is 1 to 10 times the total molar amount of iron and cobalt.

[0014] The surfactant comprises 1-70% of the total mass of iron and cobalt.

[0015] The amount of solvent used is such that the total concentration of iron and cobalt in the reaction system is 0.001~1.0 mol / L.

[0016] Preferably, the reaction temperature is 290~320℃.

[0017] Preferably, the heat preservation time is 170~190 minutes.

[0018] Preferably, the strength of the magnetic field is 300 Gs; the direction of the magnetic field is vertically downward and penetrates through the reaction vessel.

[0019] Preferably, the heating rate used to raise the temperature to the reaction temperature is 1~5℃ / min.

[0020] Preferably, the reaction product is first washed with chloroform, and then centrifuged and washed with n-hexane and anhydrous ethanol in a volume ratio of (1:1) to (1:5).

[0021] Preferably, the phase in the FeCo hard magnetic nanowire is the FeCo phase, containing FeCo phase characteristic peaks (110), (211) and (200).

[0022] Preferably, the coercivity of FeCo hard magnetic nanowires can reach 1.35 kOe.

[0023] This invention provides a method for preparing FeCo hard magnetic nanowires, comprising the following steps: mixing an iron source, a cobalt source, a reducing agent, and a solvent; heating to 70-75°C under an argon atmosphere; ultrasonicating for 12-17 min; dehydrating at 110-120°C; adding a surfactant; continuing to heat to the reaction temperature; maintaining the temperature; and applying a static micro-magnetic field during the holding period to obtain the reaction product; purifying the reaction product to obtain FeCo hard magnetic nanowires. This invention also provides a magnetic field-surfactant synergistic wet chemical method for synthesizing bct-FeCo nanowires; this method successfully prepares single-phase hard magnetic bct-FeCo ordered one-dimensional nanostructures by synergistically utilizing the lattice stress induced by surfactant ligands and the magnetic field orientation effect. These FeCo hard magnetic nanowires exhibit high coercivity. Attached Figure Description

[0024] Figure 1 The XRD pattern of FeCo nanowires prepared in Example 1 of this invention;

[0025] Figure 2 The hysteresis loop of the FeCo nanowires prepared in Example 1 of this invention;

[0026] Figure 3 This is a TEM image of the FeCo nanowires prepared in Example 1 of the present invention;

[0027] Figure 4 The image shows an HR-TEM image of the FeCo nanowires prepared in Example 1 of this invention.

[0028] Figure 5 The XRD pattern of FeCo nanowires prepared in Comparative Example 1 of this invention;

[0029] Figure 6 This is a TEM image of the FeCo nanowires prepared in Comparative Example 1 of this invention;

[0030] Figure 7 This is an HR-TEM image of the FeCo nanowires prepared in Comparative Example 1 of this invention. Detailed Implementation

[0031] This invention provides a method for preparing FeCo hard magnetic nanowires, comprising the following steps:

[0032] Iron source, cobalt source, reducing agent and solvent are mixed, heated to 70~75℃ under argon atmosphere, ultrasonically treated for 12~17min, dehydrated at 110~120℃, surfactant is added, and the temperature is further increased to the reaction temperature. The temperature is maintained and a static micro-magnetic field is applied during the holding period to obtain the reaction product.

[0033] The reaction product was purified to obtain FeCo hard magnetic nanowires.

[0034] This invention provides a magnetic field-surfactant synergistic wet chemical method for synthesizing bct-FeCo nanowires. This method utilizes surfactants as chemical ligands to apply compressive stress, and leverages a magnetic field to promote one-dimensional growth and full extrusion. This method establishes a novel template-free synthetic route for preparing magnetic nanomaterials and promoting their lattice distortion.

[0035] This method successfully fabricated single-phase hard magnetic bct-FeCo ordered one-dimensional nanostructures by synergistically utilizing the lattice stress and magnetic field orientation effects induced by surfactant ligands. This approach helps improve the magnetic properties of materials, enhances their potential for subsequent functional modification, and provides an important reference for the development of high-performance rare-earth-free permanent magnets.

[0036] This invention introduces surfactants as "ligands," whose selective adsorption on different crystal planes of nanoparticles generates differentiated interaction forces as the interparticle distance decreases. When nanoparticles approach each other, the "ligands" attached to their surfaces generate repulsive forces of varying strengths in different directions due to spatial compression, thus producing lattice stress. This effect becomes more pronounced as the interparticle distance further decreases. Furthermore, the introduction of the stress field can promote ordered diffusion. When Fe / Co atoms are arranged in a long-range ordered pattern, the difference in atomic radii between Fe and Co induces lattice distortion, ultimately forming ordered bct-FeCo nanowires.

[0037] This invention utilizes a ligand-based system to induce lattice stress in FeCo magnetic nanoparticles, achieving ordered lattice distortion. A magnetic field promotes the assembly and oriented growth of nanoparticles along the easy magnetization axis, while a surfactant exerts a squeezing effect along the growth direction, inducing lattice distortion and promoting the ordering transformation. This method holds promise for achieving long-range ordered Fe / Co atomic nanostructures and for the controllable synthesis of metastable body-centered tetragonal (bct-FeCo) structures based on the difference in atomic radii between Fe and Co, thereby effectively improving the material's coercivity. Furthermore, by combining this with an external static magnetic field for directional control, anisotropic growth of FeCo nanoparticles along the easy magnetization axis can be induced, forming one-dimensional nanowire structures. Simultaneously, the squeezing effect induced by the ligands is enhanced, further promoting the ordered diffusion process. This synergistic effect of ligands and magnetic field helps to induce significant lattice distortion in FeCo nanomaterials, enhancing their magnetic anisotropy and thus improving the overall magnetic properties of the material.

[0038] In this invention, the iron source is selected from one or more of ferric acetylacetone, ferric chloride, ferric sulfide, and ferric nitrate; the cobalt source is selected from one or more of cobalt acetylacetone, cobalt chloride, cobalt sulfide, and cobalt nitrate; the surfactant is selected from one or more of oleylamine, oleic acid, hexadecyltrimethylammonium bromide, and hexadecyltrimethylammonium chloride; and the solvent is selected from one or more of dodecylamine, octadecylamine, hexadecylamine, and trioctylamine.

[0039] In this invention, the molar ratio of iron in the iron source to cobalt in the cobalt source is (0.25~5):1, preferably (0.5~1.5):1; specifically, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1.

[0040] The amount of reducing agent used is 1 to 10 times the total molar amount of iron and cobalt, preferably 1 to 5 times; specifically, it can be 1, 2, 3, 4 or 5 times.

[0041] The surfactant comprises 1-70% of the total mass of iron and cobalt, preferably 20-30%; specifically, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0042] The amount of solvent used is such that the total concentration of iron and cobalt in the reaction system is 0.001~1.0 mol / L, preferably 0.002~0.1 mol / L; specifically, it can be 0.002 mol / L, 0.003 mol / L, 0.02 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, or 0.1 mol / L. In a specific embodiment, the molar ratio of the iron source to the cobalt source is 0.25:0.25; the molar ratio of the total amount of the iron and cobalt sources to the reducing agent is 1:1; and the molar ratio of the total amount of the iron source, cobalt source, and reducing agent to the solvent is 1:15.

[0043] In this invention, high-purity argon gas is continuously introduced. After three argon-purging cycles, the system is heated to 70-75°C to completely melt the solvent, thereby creating a uniform liquid environment that facilitates the full dispersion of precursors, surfactants, and reducing agents. Subsequently, ultrasonic treatment is performed for 12-17 minutes, preferably 15 minutes, to ensure sufficient dispersion of the precursors. After ultrasonic treatment, dehydration is carried out at 110-120°C for 30-40 minutes; the specific dehydration temperature is 110°C, 115°C, or 120°C; and the dehydration time is 30 minutes, 35 minutes, or 40 minutes.

[0044] After adding the surfactant, a reflux condenser is installed, and the temperature is increased to the reaction temperature at a rate of 1-5 °C / min and held at that temperature. The reaction temperature is 290-320 °C, specifically 290 °C, 295 °C, 300 °C, 305 °C, 310 °C, 315 °C, or 320 °C; the holding time is 170-190 min, specifically 170 min, 175 min, 180 min, 185 min, or 190 min. In this invention, a static micromagnetic field is applied during the holding period to obtain the reaction product. This invention controls the crystal orientation growth and morphological evolution of nanoparticles through an external magnetic field.

[0045] This invention achieves the synthesis of a single-phase ordered bct-FeCo structure by controlling the directional assembly of FeCo nanoparticles with a magnetic field and by utilizing the steric hindrance and compressive stress generated by the surfactant "ligand" molecular chains during the assembly process to effectively promote lattice distortion.

[0046] The present invention preferably applies a static micromagnetic field to the bottom of a three-necked flask containing the reaction raw materials; the strength of the magnetic field is 300 Gs; the magnetic field strength exhibits periodic changes to achieve precise control over the growth behavior of FeCo nanoparticles. The direction of the magnetic field is vertically downward along the flask neck and penetrates the reaction vessel. This magnetic field continues to act until the end of the heat preservation stage, after which the heating jacket is removed.

[0047] This invention purifies the reaction product to obtain FeCo hard magnetic nanowires. Preferably, a mixed solvent of anhydrous ethanol and chloroform is used for dispersion and washing; the volume ratio of anhydrous ethanol to chloroform is 1:3; the reaction product is a black mixed solution, and the volume ratio of the reaction product to the mixed solvent is 1:5. After dispersion and washing, centrifugation is performed at 6000-12000 rpm for 3 minutes. The supernatant is discarded, and the mixture of anhydrous ethanol and chloroform is added again for dispersion and centrifugation, preferably repeated 4 times. Preferably, the FeCo nanowires obtained by centrifugation are stored in n-hexane.

[0048] This invention utilizes a magnetic field-assisted wet chemical method to successfully achieve the controllable synthesis of ordered bct-FeCo hard magnetic nanomaterials. The coercivity of the one-dimensional nanowires prepared by this method reaches 1.35 kOe, which is the highest value reported in the literature for this material system to date, and its magnetic properties are significantly superior to those of products obtained by traditional synthesis methods.

[0049] To further illustrate the present invention, the following detailed description of a method for preparing FeCo hard magnetic nanowires provided by the present invention is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0050] In the following embodiments:

[0051] All preparation equipment is commercially available and can be purchased on the market. The preparation equipment and instruments include: three-necked flask, condenser, electronic balance, mechanical stirring and heating mantle, and centrifuge, etc. The precursors, solvents, surfactants, high-purity argon, high-purity nitrogen, and 95% Ar + 5% H2, 93% Ar + 7% H2, anhydrous ethanol, and chloroform used in the embodiments of this invention were all purchased from the market.

[0052] Example 1 (Changing the precursor ratio - 1)

[0053] I. Preparation of FeCo nanowire precursor solution

[0054] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0055] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0056] II. Purification of FeCo nanowires

[0057] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0058] III. Performance Testing

[0059] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0060] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.35 kOe and the saturation magnetization Ms was 87 emu / g.

[0061] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0062] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0063] All tests were conducted under standard conditions to ensure data comparability.

[0064] Example 2 (Changing the precursor ratio - 2)

[0065] I. Preparation of FeCo nanowire precursor solution

[0066] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance, with a molar ratio of 0.25:0.35. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a molar ratio of 1:1 between the two metal precursors (iron source + cobalt source) and the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of 1:15 between the two metal precursors and the reducing agent and the solvent. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0067] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0068] II. Purification of FeCo nanowires

[0069] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0070] III. Performance Testing

[0071] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0072] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.15 kOe and the saturation magnetization Ms was 82 emu / g.

[0073] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0074] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0075] All tests were conducted under standard conditions to ensure data comparability.

[0076] Example 3 (Changing centrifuge speed - 1)

[0077] I. Preparation of FeCo nanowire precursor solution

[0078] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0079] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0080] II. Purification of FeCo nanowires

[0081] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0082] III. Performance Testing

[0083] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0084] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.05 kOe and the saturation magnetization Ms was 87 emu / g.

[0085] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0086] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0087] All tests were conducted under standard conditions to ensure data comparability.

[0088] Example 4 (Changing centrifuge speed - 2)

[0089] I. Preparation of FeCo nanowire precursor solution

[0090] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0091] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0092] II. Purification of FeCo nanowires

[0093] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 12000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0094] III. Performance Testing

[0095] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0096] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 0.95 kOe and the saturation magnetization Ms was 87 emu / g.

[0097] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0098] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0099] All tests were conducted under standard conditions to ensure data comparability.

[0100] Example 5 (Changing the insulation temperature -1)

[0101] I. Preparation of FeCo nanowire precursor solution

[0102] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0103] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to oleylamine of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 340°C at a rate of 1°C / min and held at this temperature for 180 min. During the holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0104] II. Purification of FeCo nanowires

[0105] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0106] III. Performance Testing

[0107] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0108] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.12 kOe and the saturation magnetization Ms was 83 emu / g.

[0109] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0110] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0111] All tests were conducted under standard conditions to ensure data comparability.

[0112] Example 6 (Changing the insulation temperature -2)

[0113] I. Preparation of FeCo nanowire precursor solution

[0114] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0115] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 290°C at a rate of 1°C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0116] II. Purification of FeCo nanowires

[0117] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0118] III. Performance Testing

[0119] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0120] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.20 kOe and the saturation magnetization Ms was 90 emu / g.

[0121] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0122] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0123] All tests were conducted under standard conditions to ensure data comparability.

[0124] Example 7 (Changing the heating rate - 1)

[0125] I. Preparation of FeCo nanowire precursor solution

[0126] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0127] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 0.5 °C / min and held at this temperature for 180 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0128] II. Purification of FeCo nanowires

[0129] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0130] III. Performance Testing

[0131] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0132] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.01 kOe and the saturation magnetization Ms was 85 emu / g.

[0133] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0134] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0135] All tests were conducted under standard conditions to ensure data comparability.

[0136] Example 8 (Changing the heating rate - 2)

[0137] I. Preparation of FeCo nanowire precursor solution

[0138] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0139] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 5 °C / min and held at this temperature for 180 min. During the holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0140] II. Purification of FeCo nanowires

[0141] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0142] III. Performance Testing

[0143] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0144] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.12 kOe and the saturation magnetization Ms was 83 emu / g.

[0145] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0146] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0147] All tests were conducted under standard conditions to ensure data comparability.

[0148] Example 9 (Changing the heat preservation time - 1)

[0149] I. Preparation of FeCo nanowire precursor solution

[0150] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0151] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 150 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0152] II. Purification of FeCo nanowires

[0153] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0154] III. Performance Testing

[0155] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0156] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.15 kOe and the saturation magnetization Ms was 86 emu / g.

[0157] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0158] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0159] All tests were conducted under standard conditions to ensure data comparability.

[0160] Example 10 (Changing the heat preservation time - 2)

[0161] I. Preparation of FeCo nanowire precursor solution

[0162] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0163] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to oleylamine of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 1°C / min and held at this temperature for 250 min. During the holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0164] II. Purification of FeCo nanowires

[0165] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0166] III. Performance Testing

[0167] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0168] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.05 kOe and the saturation magnetization Ms was 85 emu / g.

[0169] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0170] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0171] All tests were conducted under standard conditions to ensure data comparability.

[0172] Example 11 (Changing the magnetic field strength by 1)

[0173] I. Preparation of FeCo nanowire precursor solution

[0174] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0175] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to oleylamine of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 1°C / min and held at this temperature for 150 min. During the holding period, a static micro-magnetic field with a constant strength of 200 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0176] II. Purification of FeCo nanowires

[0177] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0178] III. Performance Testing

[0179] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0180] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.08 kOe and the saturation magnetization Ms was 86 emu / g.

[0181] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0182] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0183] All tests were conducted under standard conditions to ensure data comparability.

[0184] Example 12 (Changing the magnetic field strength -2)

[0185] I. Preparation of FeCo nanowire precursor solution

[0186] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0187] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 1°C / min and held at this temperature for 150 min. During the holding period, a static micro-magnetic field with a constant strength of 1000 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0188] II. Purification of FeCo nanowires

[0189] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0190] III. Performance Testing

[0191] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0192] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.18 kOe and the saturation magnetization Ms was 86 emu / g.

[0193] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0194] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0195] All tests were conducted under standard conditions to ensure data comparability.

[0196] Example 13 (Changing the reducing agent ratio -1)

[0197] I. Preparation of FeCo nanowire precursor solution

[0198] First, the iron source acetylacetone Fe(acac)3 and the cobalt source acetylacetone Co(acac)2 were weighed using an electronic balance, with a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a molar ratio of 2:1 between the two metal precursors (iron source + cobalt source) and the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing the solvent hexadecylamine, with a molar ratio of 1:15 between the two metal precursors and the reducing agent and the solvent. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0199] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 150 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0200] II. Purification of FeCo nanowires

[0201] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0202] III. Performance Testing

[0203] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0204] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.06 kOe and the saturation magnetization Ms was 92 emu / g.

[0205] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0206] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0207] All tests were conducted under standard conditions to ensure data comparability.

[0208] Example 14 (Changing the reducing agent ratio - 2)

[0209] I. Preparation of FeCo nanowire precursor solution

[0210] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a molar ratio of 1:2 between the two metal precursors (iron source + cobalt source) and the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent at a molar ratio of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0211] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at this temperature for 150 min. During this holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0212] II. Purification of FeCo nanowires

[0213] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0214] III. Performance Testing

[0215] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0216] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 0.96 kOe and the saturation magnetization Ms was 91 emu / g.

[0217] 3. Morphology observation: The morphology of the sample was observed to be nanowire morphology by field emission transmission electron microscopy (TEM).

[0218] 4. Crystal structure analysis: X-ray diffraction (XRD) was used to analyze the crystal structure and phase composition.

[0219] All tests were conducted under standard conditions to ensure data comparability.

[0220] Comparative Example 1 (including only the "ligand" system)

[0221] I. Preparation of FeCo nanowire precursor solution

[0222] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0223] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The solution was then heated to 300°C at a rate of 1°C / min and held at that temperature for 180 min.

[0224] II. Purification of FeCo nanowires

[0225] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0226] III. Performance Testing

[0227] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0228] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 0.98 kOe and the saturation magnetization Ms was 95 emu / g.

[0229] 3. Morphological observation: The morphology of the sample was characterized by field emission transmission electron microscopy (TEM). It was observed that the sample was mainly composed of a large number of nanoparticles and a small number of nanowires, and the overall sample exhibited the morphological characteristics of nanoparticles.

[0230] 4. Crystal Structure Analysis: The crystal structure and phase composition of the sample were analyzed by X-ray diffraction (XRD). The diffraction pattern showed that the sample had a body-centered cubic (bcc) structure, and no superlattice diffraction peak representing an ordered bct structure appeared near 27°.

[0231] All tests were conducted under standard conditions to ensure data comparability.

[0232] Comparative Example 2 (including magnetic field induction only)

[0233] I. Preparation of FeCo nanowire precursor solution

[0234] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0235] The temperature was then increased to 300°C at a rate of 1°C / min and held at that temperature for 180 min. During the holding period, a static micro-magnetic field with a constant strength of 300 Gs was applied to the bottom of the three-necked flask, directed downwards along the flask neck. This magnetic field remained in effect until the end of the holding period, after which the heating mantle was removed.

[0236] II. Purification of FeCo nanowires

[0237] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0238] III. Performance Testing

[0239] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0240] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 0.81 kOe and the saturation magnetization Ms was 85 emu / g.

[0241] 3. Morphological observation: The morphology of the samples was characterized using field emission transmission electron microscopy (TEM). The results showed that the samples were mainly composed of a large number of nanoparticles, with significant agglomeration, and signs of oxidation were observed on the surface.

[0242] 4. Crystal Structure Analysis: The crystal structure and phase composition of the sample were analyzed by X-ray diffraction (XRD). The diffraction pattern showed that the sample had a body-centered cubic (bcc) structure. No superlattice diffraction peak representing an ordered bcc structure appeared near 27°, while a CoO diffraction peak appeared near 43°.

[0243] All tests were conducted under standard conditions to ensure data comparability.

[0244] Comparative Example 3 (Changing the magnetic field, exhibiting periodic changes -1)

[0245] I. Preparation of FeCo nanowire precursor solution

[0246] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0247] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During the holding period, an alternating magnetic field was applied to the bottom of the three-necked flask, with the magnetic field strength varying between +300 Gs and -300 Gs at a frequency of 500 times / min, directed downwards along the flask neck. This magnetic field continued until the end of the holding period, after which the heating mantle was removed.

[0248] II. Purification of FeCo nanowires

[0249] After cooling the obtained black mixed solution to room temperature, it was first washed with chloroform, and then dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform: mixed solution = 1:5) and the volume ratio of anhydrous ethanol to chloroform was 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0250] III. Performance Testing

[0251] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0252] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 1.05 kOe and the saturation magnetization Ms was 85 emu / g.

[0253] 3. Morphological observation: The morphology of the sample was characterized by field emission transmission electron microscopy (TEM). It was observed that the sample was composed of short nanorods and nanospheres of uneven size, presenting a composite morphology.

[0254] 4. Crystal structure analysis: The crystal structure and phase composition were analyzed using X-ray diffraction (XRD). The diffraction pattern showed that the sample had a body-centered cubic (bcc) structure, and no superlattice diffraction peak representing an ordered bct structure appeared near 27°.

[0255] All tests were conducted under standard conditions to ensure data comparability.

[0256] Comparative Example 4 (Changing the magnetic field, exhibiting periodic changes -2)

[0257] I. Preparation of FeCo nanowire precursor solution

[0258] First, the iron precursor Fe(acac)3 and the cobalt precursor Co(acac)2 were weighed using an electronic balance at a molar ratio of 0.25:0.25. Then, the reducing agent 1,2-hexadecanediol was weighed, resulting in a 1:1 molar ratio of the two metal precursors (iron source + cobalt source) to the reducing agent 1,2-hexadecanediol. The metal precursors and reducing agent were added to a three-necked flask containing hexadecamine solvent, with a molar ratio of the two metal precursors and reducing agent to solvent of 1:15. The mixture was heated to 115°C using a heating mantle and held at this temperature for 35 min to remove moisture.

[0259] Subsequently, the surfactants oleic acid and oleylamine were added sequentially to the mixed solution, with a total volume-to-solvent molar ratio of oleic acid to solvent of 1:10 and a volume ratio of oleic acid to oleylamine of 1:1. The temperature was then increased to 300°C at a rate of 1°C / min and held at this temperature for 180 min. During the holding period, an alternating magnetic field was applied to the bottom of the three-necked flask, with the magnetic field strength varying between +300 Gs and -300 Gs at a frequency of 1500 times / min, directed downwards along the flask neck. This magnetic field continued until the end of the holding period, after which the heating mantle was removed.

[0260] II. Purification of FeCo nanowires

[0261] After cooling the obtained black mixed solution to room temperature, it was dispersed and washed with anhydrous ethanol and chloroform. The amount of anhydrous ethanol and chloroform added was 1:5 (anhydrous ethanol + chloroform : mixed solution = 1:5) and the volume ratio of anhydrous ethanol : chloroform = 1:3. Then, it was centrifuged at 10,000 rpm for 3 min. The supernatant was discarded, and the dispersion and centrifugation steps of adding anhydrous ethanol and chloroform were repeated 4 times. The obtained FeCo nanowires were stored in n-hexane.

[0262] III. Performance Testing

[0263] 1. Phase analysis: The phase of the sample was characterized by X-ray diffraction (XRD) and was found to be FeCo phase, which contained characteristic peaks of FeCo phase (110), (211) and (200).

[0264] 2. Magnetic property test: The hysteresis loop of the sample at room temperature was measured using a vibrating sample magnetometer (VSM), and the coercivity Hc was 0.68 kOe and the saturation magnetization Ms was 112 emu / g.

[0265] 3. Morphological observation: The morphology of the sample was characterized by field emission transmission electron microscopy (TEM). The results showed that the sample as a whole had an equiaxed nanosphere structure and no obvious nanowire morphology was observed.

[0266] 4. Crystal Structure Analysis: The crystal structure and phase composition of the sample were analyzed by X-ray diffraction (XRD). The diffraction pattern showed that the sample had a body-centered cubic (bcc) structure, and no superlattice diffraction peak representing an ordered bct structure appeared near 27°.

[0267] All tests were conducted under standard conditions to ensure data comparability.

[0268] As shown in the above embodiments, this invention provides a method for preparing FeCo hard magnetic nanowires, comprising the following steps: mixing an iron source, a cobalt source, a reducing agent, and a solvent; heating to 70-75°C under an argon atmosphere; ultrasonic treatment for 12-17 min; dehydration at 110-120°C; adding a surfactant; continuing to heat to the reaction temperature; maintaining the temperature; and applying a static micro-magnetic field during the holding period to obtain the reaction product; purifying the reaction product to obtain FeCo hard magnetic nanowires. This invention provides a magnetic field-surfactant synergistic wet chemical method for synthesizing bct-FeCo nanowires; this method successfully prepares single-phase hard magnetic bct-FeCo ordered one-dimensional nanostructures by synergistically utilizing the lattice stress induced by surfactant ligands and the magnetic field orientation effect. The FeCo hard magnetic nanowires exhibit high coercivity. Experimental results show that the coercivity Hc of the FeCo hard magnetic nanowires is 0.95-1.35 kOe; and the saturation magnetization is 82-90 emu / g.

[0269] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing FeCo hard magnetic nanowires, comprising the following steps: Iron source, cobalt source, reducing agent and solvent are mixed, heated to 70~75℃ under argon atmosphere, ultrasonically treated for 12~17min, dehydrated at 110~120℃, surfactant is added, and the temperature is further raised to the reaction temperature. The temperature is maintained and a static micro-magnetic field is applied during the holding period to obtain the reaction product. The reaction product was purified to obtain FeCo hard magnetic nanowires.

2. The preparation method according to claim 1, characterized in that, The iron source is selected from one or more of ferric acetylacetone, ferric chloride, ferric sulfide, and ferric nitrate; The cobalt source is selected from one or more of cobalt acetylacetonate, cobalt chloride, cobalt sulfide, and cobalt nitrate; The surfactant is selected from one or more of oleylamine, oleic acid, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride; The solvent is selected from one or more of dodecylamine, octadecamine, hexadecamine, and trioctylamine.

3. The preparation method according to claim 1, characterized in that, The molar ratio of iron in the iron source to cobalt in the cobalt source is (0.25~5):1; The amount of the reducing agent used is 1 to 10 times the total molar amount of iron and cobalt. The surfactant comprises 1-70% of the total mass of iron and cobalt. The amount of solvent used is such that the total concentration of iron and cobalt in the reaction system is 0.001~1.0 mol / L.

4. The preparation method according to claim 1, characterized in that, The reaction temperature is 290~320℃.

5. The preparation method according to claim 1, characterized in that, The heat preservation time is 170~190 minutes.

6. The preparation method according to claim 1, characterized in that, The magnetic field strength is 300 Gs; the direction of the magnetic field is vertically downward and penetrates through the reaction vessel.

7. The preparation method according to claim 1, characterized in that, The heating rate used to raise the temperature to the reaction temperature is 1~5℃ / min.

8. The preparation method according to claim 1, characterized in that, The reaction product was first washed with chloroform, and then centrifuged and washed with a mixed solvent of n-hexane and anhydrous ethanol in a volume ratio of (1:1) to (1:5).

9. The preparation method according to claim 1, characterized in that, The phase in the FeCo hard magnetic nanowire is the FeCo phase, which contains FeCo phase characteristic peaks (110), (211) and (200).

10. The preparation method according to claim 1, characterized in that, The coercivity of FeCo hard magnetic nanowires can reach 1.35 kOe.

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