Orthorhombic barium single iron oxide nanofiber / rod and preparation method and application thereof

Abstract

The application discloses orthogonal barium monoferrite nanofibers / rods and a preparation method and application thereof. The method is characterized in that barium acetate is used as a barium source, acetylacetone iron is used as an iron source, ethanol and acetic acid are used as solvents, polyvinylpyrrolidone is used as a wrapping and complexing stabilizer, and the orthogonal barium monoferrite is prepared and synthesized in an organic phase system by combining electrostatic spinning technology and a calcination process, so that the orthogonal barium monoferrite has high purity and regular nanofiber / rod morphology. The application has the advantages of simple operation steps, low cost, easy implementation, less use of test reagents, high yield of the prepared orthogonal barium monoferrite nanofiber / rod, and good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of inorganic oxide semiconductor nanomaterials, in particular to a preparation method of orthorhombic barium ferrite (BaFe2O4) nanofiber / rod. BACKGROUND

[0002] Since the last century, the preparation of inorganic oxide semiconductor nanofiber / rod has attracted extensive attention and has become a very challenging topic in the field of sol-gel science. Due to the nanoscale size and quantum confinement effect, these oxide semiconductor nanofiber / rods have potential important applications in information, energy, environment, biomedical technology, such as nanoelectronics, high-speed field effect transistors, lithium ion battery anodes and cathodes, biological and chemical sensors, etc. Due to the low cost, good chemical stability, corrosion resistance and other excellent properties, barium ferrite is widely used in permanent magnet materials, data storage, photocatalysis, ceramic pigments, wave-absorbing and radiation-resistant, sensing, heavy metal adsorption and chemical looping gasification, etc. In particular, orthorhombic barium ferrite (BaFe2O4), Francesco Mezzadri et al. of Rutherford Appleton Laboratory in the UK published in Nature Communication (2022, Vol. 13, 7968: 1-10) titled "γ-BaFe2O4: a fresh playground for room temperature multiferroicity", which is a previously undiscovered room temperature multiferroic material, with ferroelectric and ferromagnetic Curie temperatures reaching 1038K and 890K, respectively. Shen Laihong's research group of Southeast University published in Fuel (2022, Vol. 307, 121847: 1-14) titled "Mechanism study on the high-performance BaFe2O4 during chemical looping gasifcation", which reports the excellent performance of orthorhombic barium ferrite in the preparation of CO gas by chemical looping gasification. Although nanofiber / rod can increase the specific surface area and the preferred growth of the grain, which helps to optimize these properties, there is no report on orthorhombic barium ferrite (BaFe2O4) nanofiber / rod.

[0003] After investigating the existing literature, it is found that the patent with publication number CN116949602A discloses a hollow fibrous barium ferrite and a preparation method thereof. Barium nitrate or barium chloride is used as a barium source, iron nitrate or iron carbonate or ferrous carbonate is used as an iron source, and N,N-dimethylformamide or tetrahydrofuran or dimethylformamide or dimethylacetamide or N-methylpyrrolidone or ethanol and other polar solutions are used as solvents. Citric acid and polyvinylpyrrolidone are added as solubilizers, and the barium ferrite fiber sponge precursor is collected by airflow spinning method. Finally, the hollow fibrous barium ferrite (BaFe 12 O 19 ) is obtained by heating and calcining in a muffle furnace. However, airflow spinning is to use high-speed airflow to pull the fibers into a fiber bundle and then spin into a thread, which requires accurate control of airflow and temperature. Barium nitrate, barium chloride and other raw materials are difficult to dissolve in ethanol and other polar solvents. Even if citric acid is added to promote mixing, the barium source, iron source and polyvinylpyrrolidone mixed together are a precursor sol, not a uniformly mixed solution, which may affect the uniformity of the crystal form of the final material. In addition, the prepared ferrite is suitable for strong magnets and is not suitable as a soft magnetic material. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to provide a kind of barium monoferrite (BaFe2O4) nanofiber / rod and its preparation method, which uses barium acetate as barium source, iron acetylacetone as iron source, ethanol and acetic acid as solvent, polyvinylpyrrolidone as wrapping and complexing stabilizer, and prepares barium monoferrite nanofiber with high purity and regular morphology.

[0005] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0006] A preparation method of barium monoferrite nanofiber / rod, specifically comprising the following steps:

[0007] (1) Take barium acetate and iron acetylacetone containing barium and iron with a mole ratio of 1:2, disperse them in 4-10 ml of a mixed solution of equal volumes of acetic acid and ethanol, and add polyvinylpyrrolidone, stir and mix uniformly to form a transparent precursor solution. The mass fraction of polyvinylpyrrolidone in the precursor solution is 5-15%;

[0008] (2) The precursor solution prepared in step (1) is obtained by electrospinning technology to obtain precursor nanofiber;

[0009] (3) The precursor fiber prepared in step (2) is dried to form dry precursor nanofiber;

[0010] (4) calcining the precursor fiber prepared in step (3) at 600-800 DEG C in air to obtain orthorhombic barium monoferrite BaFe2O4 nanofiber, or at 800-950 DEG C to obtain orthorhombic barium monoferrite BaFe2O4 nanorod.

[0011] Specifically, the drying temperature in step (3) is 60-110 DEG C, 60-70 DEG C, 70-80 DEG C, 80-90 DEG C, 90-100 DEG C, or 100-110 DEG C.

[0012] Specifically, the process parameters of electrospinning in step (2) are: perfusion speed 0.36 ml / h, voltage 18 kV, and receiving distance 15 cm.

[0013] Preferably, the calcining temperature in step (4) is 700 DEG C-900 DEG C.

[0014] The acetic acid in step (1) is both a solvent and a dissolution promoter, and the addition of acetic acid is conducive to the mixing of barium acetate and other raw materials, and if acetic acid is omitted, it is difficult to form a transparent and uniformly mixed precursor solution.

[0015] The orthorhombic barium monoferrite nanofiber prepared by the above method is used as a soft magnetic material, and the orthorhombic barium monoferrite nanorod is used as a permanent magnetic material.

[0016] The orthorhombic barium monoferrite nanorod prepared by the above method has great application potential in permanent magnetic materials, nanospin electronics and information data storage.

[0017] Compared with the prior art, the present application has the following beneficial effects: (1) by adjusting the types of barium source, iron source and solvent, a mixed and uniformly mixed precursor solution is formed from the barium source, iron source and polyvinylpyrrolidone under less solvent, and the orthorhombic barium monoferrite nanofiber / rod prepared has high purity and regular morphology; (2) it is found that with the increase of calcining temperature, the impurities in the crystal phase are less and less, but the material diameter is larger and larger, and the specific surface area is smaller and smaller, therefore, by comprehensive consideration, 700 DEG C and 900 DEG C are selected as the best calcining temperature; (3) the preparation steps are simple, the amount of used reagents is small, the cost is low, and it is easy to implement. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1A X-ray diffraction patterns (XRD) of the orthorhombic barium monoferrite nanofiber / rod prepared at different calcining temperatures in Example 1.

[0019] Figure 1B X-ray diffraction patterns (XRD) of the orthorhombic barium monoferrite nanofiber / rod prepared at different calcining temperatures in Example 1.

[0020] Figure 1CX-ray diffraction pattern (XRD) of orthorhombic barium monoferrite nanofiber / rod prepared at different calcination temperature in Example 1.

[0021] Figure 2 Scanning electron microscope pictures (SEM) of orthorhombic barium monoferrite nanofiber prepared at 700℃ calcination temperature in Example 1 at different magnification, wherein A is 10,000 times magnification, B is 20,000 times magnification, C is 50,000 times magnification, and D is 100,000 times magnification.

[0022] Figure 3 Scanning electron microscope pictures (SEM) of orthorhombic barium monoferrite nanorod prepared at 900℃ calcination temperature in Example 1 at different magnification, wherein A is 10,000 times magnification, B is 20,000 times magnification, C is 50,000 times magnification, and D is 100,000 times magnification.

[0023] Figure 4 Hysteresis loop diagram of orthorhombic barium monoferrite nanofiber / rod prepared at different calcination temperature in Example 1, left is 700℃, right is 900℃.

[0024] Figure 5 Scanning electron microscope pictures (SEM) of orthorhombic barium monoferrite prepared at 900℃ calcination temperature in Comparative Example 1. DETAILED DESCRIPTION

[0025] The application will be further described below in conjunction with specific embodiments and the accompanying drawings. The process, conditions, reagents, experimental methods, etc. for implementing the application are all general knowledge and common sense in the art, and the application does not have special restrictions.

[0026] Example 1

[0027] The preparation method of the orthorhombic barium monoferrite nanofiber involved in the present embodiment specifically comprises the following steps:

[0028] (1) At room temperature, 0.9613 g of barium acetate and iron acetylacetonate mixture containing barium and iron in a molar ratio of 1:2 was weighed and dispersed in 6 ml of an equal volume mixture of acetic acid and ethanol, and stirred for 12 h to form a transparent precursor solution;

[0029] (2) 0.630 g of polyvinylpyrrolidone was added to the precursor solution prepared in step (1) and stirred uniformly to form a transparent solution;

[0030] (3) The precursor solution prepared in step (2) was obtained by electrospinning technology, and the process parameters were as follows: infusion speed 0.36 ml / h, voltage 18 kV, and receiving distance 15 cm.

[0031] (4) drying the precursor nanofiber prepared in step (3) at 80℃ for 3h to form a dried precursor nanofiber;

[0032] (5) calcining the precursor nanofiber prepared in step (4) at a temperature increasing rate of 3℃ / min to 500℃, 600℃, 700℃, 800℃, 900℃ and 950℃ respectively for 2h to obtain a corresponding orthorhombic barium monoferrite material.

[0033] The XRD of the orthorhombic barium monoferrite material prepared at different temperatures was measured, and the experimental results showed that the orthorhombic barium ferrite was difficult to be prepared at a calcination temperature of 500℃, and the orthorhombic barium ferrite could be prepared at 600℃, 700℃, 800℃, 900℃ and 950℃, and the impurities in the crystal phase of the orthorhombic barium monoferrite material were less and less as the temperature increased. As shown in Figure 1, when the calcination temperature was 700℃, there were BaO (PDF no. 30-0143) or Ba2Fe 14 O 22 (PDF no. 40-1047) impurities (elliptical position near 31.9°) in the orthorhombic barium monoferrite nanofiber, and the orthorhombic barium monoferrite material prepared at a calcination temperature of 900℃ had the best crystal structure.

[0034] The SEM of the orthorhombic barium monoferrite material prepared at different temperatures was measured, and the experimental results showed that as the temperature increased, the diameter of the orthorhombic barium monoferrite material became larger and the length became shorter, and the fiber-like structure was prepared at 600℃, 700℃ and 800℃, and the nanorod structure was formed when the temperature exceeded 800℃. For example, the average diameter of the nanofiber prepared at 700℃ was 260nm, and the orthorhombic barium ferrite prepared at 900℃ was a nanorod structure, and the nanorod morphology was uniform, and the average diameter and length were 300nm and 4 microns respectively.

[0035] The hysteresis loop of the orthorhombic barium monoferrite material prepared at different temperatures was measured, and as shown in the left graph of Figure 2, the saturation magnetization of the nanofiber prepared at 700℃ reached 0.54emu / g, the remanence was 0.06emu / g, and the coercive field was 530Oe, which was a soft magnet, and had great application potential in magnetic storage. Figure 4 The saturation magnetization of the nanorod prepared at 900℃ reached 1.5emu / g, the remanence reached 0.66emu / g, and the coercive field was 4350Oe, which was a hard magnet and was used for permanent magnet, and compared with the existing permanent magnet containing rare earth, the cost was greatly reduced.

[0036] Example 2

[0037] The preparation method of the orthorhombic barium monoferrite nanofiber / nanorod disclosed in the embodiment specifically comprises the following steps:

[0038] (1) At room temperature, 0.9613 g of barium acetate and iron acetylacetonate mixture containing barium and iron with a molar ratio of 1:2 was weighed, dispersed in 6 ml of acetic acid and ethanol mixed solution with equal volume, and 0.730 g of polyvinylpyrrolidone was added, stirred for 24 h to form a transparent precursor solution;

[0039] (2) The precursor solution prepared in step (1) was obtained by electrospinning technology to obtain precursor nanofibers, and the process parameters were: infusion speed 0.36 ml / h, voltage 18 kV, and receiving distance 15 cm.

[0040] (3) The precursor fibers prepared in step (2) were dried in a blast drying oven at 100℃ to form dried precursor nanofibers;

[0041] (4) The precursor fibers prepared in step (3) were calcined at 750℃ with a temperature rising rate of 5℃ / min for 3h to obtain orthogonal barium single iron oxide nanofibers.

[0042] Comparative Example 1

[0043] This comparative example is the same as Example 1 except for step (1), and the specific method is as follows:

[0044] (1) At room temperature, 0.9613 g of barium acetate and iron acetylacetonate mixture containing barium and iron with a molar ratio of 1:2 was weighed, dispersed in 6 ml of acetic acid and ethanol mixed solution with equal volume, and 0.730 g of polyvinylpyrrolidone was added, stirred for 24 h to form a transparent precursor solution;

[0045] From Figure 5 It can be seen that the final product obtained by calcining at 900℃ in this comparative example shows adhesion phenomenon and is difficult to form fibers.

[0046] Comparative Example 2

[0047] (1) At room temperature, 0.9613 g of barium acetate and iron acetylacetonate mixture containing barium and iron with a molar ratio of 1:2 was weighed, dispersed in 6 ml of acetic acid and ethanol mixed solution with equal volume, and 0.730 g of polyvinylpyrrolidone was added, stirred for 24 h to form a transparent precursor solution;

[0048] (2) 0.630 g of polyvinylpyrrolidone was added to the precursor solution prepared in step (1) and stirred uniformly to form a transparent solution;

[0049] (3) The precursor solution prepared in step (2) was obtained by electrospinning technology to obtain precursor nanofibers, and the process parameters were: infusion speed 0.36 ml / h, voltage 18 kV, and receiving distance 15 cm.

[0050] (4) The precursor fibers prepared in step (3) were dried at 80℃ for 3h to form dried precursor nanofibers;

[0051] (5) The precursor fiber prepared in step (4) was calcined at 600°C for 2h with a temperature increasing rate of 3°C / min, but it was difficult to obtain the orthorhombic barium monoferrite material.

Claims

1. A method for preparing orthogonal barium monoferrite nanofibers / rods, characterized in that, Specifically, the following steps are included: (1) Weigh out barium acetate and iron acetylacetone containing barium and iron in a molar ratio of 1:2, disperse them in a mixture of 4-10 ml of acetic acid and ethanol of equal volume, add polyvinylpyrrolidone, stir and mix evenly to form a transparent precursor solution, the mass fraction of polyvinylpyrrolidone in the precursor solution is 5-15%. (2) The precursor solution obtained in step (1) is used to obtain precursor nanofibers by electrospinning. (3) Dry the precursor fibers obtained in step (2) to form dry precursor nanofibers; (4) The precursor fibers obtained in step (3) are calcined in air at 600-800℃ to obtain orthogonal barium ferrite BaFe2O4 nanofibers, or calcined at 800-950℃ to obtain orthogonal barium ferrite BaFe2O4 nanorods.

2. The method for preparing orthogonal barium monoferrite nanofibers / rods according to claim 1, characterized in that, The drying temperature in step (3) is 60-110℃.

3. The method for preparing orthogonal barium monoferrite nanofibers / rods according to claim 1, characterized in that, The electrospinning process parameters in step (2) are: injection speed 0.36 ml / h, voltage 18 kV, and receiving distance 15 cm.

4. The method for preparing orthogonal barium monoferrite nanofibers / rods according to claim 1, characterized in that, The calcination temperature in step (4) is 700℃-900℃.

5. Orthogonal barium monoferrite nanofibers / rods prepared by the preparation method according to any one of claims 1-4.

6. The application of the orthogonal barium single ferrite nanofibers as described in claim 5 as soft magnetic materials, and the application of the orthogonal barium single ferrite nanorods as permanent magnet materials.

7. The application of the orthogonal barium monoferrite nanorods according to claim 5 in permanent magnet materials, nano-spintronics, and information data storage.

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