Samarium ferrite powder and preparation method thereof
The preparation of samarium ferrite powder by hydrothermal reaction method solves the problems of high-temperature calcination and difficult to control morphology in traditional methods, and realizes the preparation of samarium ferrite powder with narrow particle size and spherical shape, reducing energy consumption and production costs.
Patent Information
- Application Number
- CN202510382453.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-06-27
AI Technical Summary
The preparation method of traditional perovskite samarium ferrite has problems such as high-temperature calcination leading to high energy consumption and large grain growth, difficult to control morphology, and harsh reaction conditions.
By using the hydrothermal reaction method, a samarium brine solution, water-soluble iron salt and citric acid were mixed and stirred, a hydrothermal reaction was carried out at 180-200°C for 6-15 hours, followed by solid-liquid separation, washing, drying and calcination, and a samarium ferrite powder with a particle size of 2-3 μm and a spherical degree was prepared.
The preparation of samarium ferrite powder with narrow particle size and spherical shape is achieved, which reduces energy consumption, simplifies process conditions, reduces production costs, and improves the controllability of the material's morphology.
Smart Images
Figure CN120208301A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a samarium ferrite powder and a preparation method thereof. Background Art
[0002] Samarium ferrite (SmFeO3) is a rare earth ferrite material with a perovskite structure. Due to its unique crystal structure and excellent physical and chemical properties, it has broad application prospects in the fields of magnetic materials, catalysis, rare earth polishing, gas sensing, photocatalysis, and information storage.
[0003] Traditional preparation methods of perovskite-type samarium ferrite usually adopt solid-phase reaction method or sol-gel method, and these methods have the following problems:
[0004] 1. High-temperature calcination: Traditional methods require high-temperature (usually higher than 900 °C) calcination, which has high energy consumption and is prone to grain growth, affecting the specific surface area and activity of the material;
[0005] 2. Difficult to control morphology: The materials prepared by the solid-phase reaction method are usually irregular particles with poor morphology uniformity, which limits their applications in the fields of catalysis, sensing, etc.;
[0006] 3. Harsh reaction conditions: Some wet chemical methods require complex process conditions or expensive raw materials, increasing the production cost. Summary of the Invention
[0007] An object of the present invention is to provide a preparation method of samarium ferrite powder. The samarium ferrite powder prepared by this preparation method has good sphericity, a particle size of 2 - 3 μm, and a narrow particle size distribution. This preparation method adopts hydrothermal reaction. Another object of the present invention is to provide a samarium ferrite powder prepared according to the above preparation method.
[0008] The present invention adopts the following technical solutions to achieve the above objects.
[0009] On the one hand, the present invention provides a preparation method of samarium ferrite powder, including the following steps:
[0010] 1) Mix an aqueous solution of samarium salt, a water-soluble iron salt, and citric acid and stir for 1 - 3 h to obtain an initial reactant;
[0011] 2) Carry out hydrothermal reaction on the initial reactant at 180 - 200 °C for 6 - 15 h to obtain an intermediate reactant;
[0012] 3) Separate the solid and liquid of the intermediate reactant, wash the separated solid, and dry the washed solid to obtain a precursor;
[0013] 4) Calcinate the precursor in an inert atmosphere at 700 - 900 °C for 1 - 5 h to obtain samarium ferrite powder. In this way, samarium ferrite powder with good sphericity, a particle size of 2 - 3 μm, and a narrow particle size distribution can be obtained.
[0014] In the prior art, there are research reports on obtaining samarium ferrite by high-temperature sintering using samarium oxide and iron oxide as raw materials; there are also research reports on obtaining samarium ferrite by using iron salts and samarium salts as raw materials and adopting the sol-gel method or precipitation method. The morphologies of the obtained samarium ferrite are in the form of flakes or irregular shapes. So far, there is still no report on obtaining samarium ferrite powder with a particle size of 2 - 3 μm and good sphericity by hydrothermal reaction.
[0015] The present invention does not add any surfactant as a dispersant or binder. The surfactants mentioned here include but are not limited to polyvinylpyrrolidone, polyethylene glycol, cetyltrimethylammonium bromide, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate, etc. The present invention does not add organic solvents including alcohols (such as ethylene glycol). The present invention only uses water as a solvent. The water can be deionized water, purified water, or distilled water.
[0016] In step 1), according to an embodiment of the present invention, under stirring, sequentially add a water-soluble iron salt and citric acid to the samarium salt aqueous solution. After adding, continue stirring for 1 - 3 h to obtain an initial reactant. This step can be carried out at room temperature. Preferably, continue stirring for 1.5 - 2 h. This is beneficial to obtaining samarium ferrite powder with a specific morphology and particle size.
[0017] According to a specific embodiment of the present invention, under stirring, add a water-soluble iron salt to the samarium salt aqueous solution. After the water-soluble iron salt is dissolved, add citric acid to the solution. After adding, continue stirring for 1 - 3 h to obtain an initial reactant.
[0018] In the present invention, the samarium salt aqueous solution can be formed by dissolving a water-soluble samarium salt in water. The water-soluble samarium salt is selected from one of samarium nitrate, samarium chloride, samarium sulfate, and samarium acetate, preferably samarium nitrate. The water-soluble samarium salt can contain crystal water or can be anhydrous.
[0019] According to a specific embodiment of the present invention, the samarium salt aqueous solution is formed by dissolving samarium nitrate hexahydrate in water.
[0020] In the present invention, the water-soluble iron salt is selected from one of ferric chloride, ferric nitrate, and ferric sulfate, preferably ferric nitrate. The water-soluble iron salt can contain crystal water or can be anhydrous. According to a specific embodiment of the present invention, the water-soluble iron salt is ferric nitrate nonahydrate.
[0021] In the present invention, citric acid can contain crystal water or can be anhydrous.
[0022] Step 2) is a hydrothermal reaction. The initial reactants are subjected to a hydrothermal reaction in a reaction kettle. The reaction kettle can be sealed first so that no gas or liquid leaks out during the reaction. The reaction kettle can be a stainless-steel reaction kettle with a polytetrafluoroethylene lining. The reaction temperature in Step 2) can be 180 - 200 °C, for example, it can be 180 °C, 185 °C, 190 °C, 195 °C, 200 °C. The time of the hydrothermal reaction can be 6 - 15 h, preferably 8 - 12 h, and more preferably 10 - 11 h. By controlling the dosage ratios of samarium salt, iron salt, and citric acid, the stirring time after preliminary mixing, and the temperature and time of the hydrothermal reaction within specific ranges in the present invention, it is more conducive to obtaining the samarium ferrite powder with specific morphology and particle size in the present invention.
[0023] In Step 3), the intermediate reactants can be cooled first, for example, to room temperature, and then solid-liquid separation is carried out. The solid-liquid separation can be filtration or centrifugation, preferably centrifugation. After solid-liquid separation, the separated solid can be washed first, and then the washed solid is dried to obtain a precursor. This is conducive to obtaining a samarium ferrite powder with higher purity.
[0024] In Step 4), calcining the precursor in an inert atmosphere is more conducive to controlling the morphology of the obtained samarium ferrite powder and will not cause over-oxidation. After calcination, it can be naturally cooled to room temperature and then ground to obtain the samarium ferrite powder.
[0025] In the present invention, the calcination temperature can be 700 - 900 °C, preferably 750 - 850 °C, and more preferably 780 - 800 °C. The calcination time can be 1 - 5 h, preferably 1 - 4 h, and more preferably 1 - 3 h. The calcination can be carried out in a tubular furnace or a muffle furnace.
[0026] According to the method for preparing the samarium ferrite powder of the present invention, preferably, in Step 1), the molar concentration of the samarium salt aqueous solution is 0.005 - 0.5 mol / L; the samarium salt in the samarium salt aqueous solution is selected from at least one of samarium nitrate, samarium chloride, samarium sulfate, and samarium acetate. This is conducive to obtaining a samarium ferrite powder with a narrow particle size distribution and good sphericity.
[0027] In the present invention, the molar concentration of the samarium salt aqueous solution can be 0.005 - 0.5 mol / L, preferably 0.008 - 0.2 mol / L, more preferably 0.01 - 0.08 mol / L, and even more preferably 0.02 - 0.05 mol / L.
[0028] According to the method for preparing the samarium ferrite powder of the present invention, preferably, in Step 1), the water-soluble iron salt is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate.
[0029] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 1), the molar ratio of iron element in the water-soluble iron salt to samarium element in the samarium salt aqueous solution is 1:1 to 1.05; the molar ratio of citric acid to the water-soluble iron salt is 2 to 2.4:1. This is beneficial to improving the balling rate of the obtained samarium ferrite powder, and the spherical particles are not easily broken and have a good sphericity. The present invention finds that if the amount of the iron salt increases, the particle size distribution of the obtained samarium ferrite powder becomes wider and the sphericity becomes worse.
[0030] In the present invention, the molar ratio of iron element in the water-soluble iron salt to samarium element in the samarium salt aqueous solution can be 1:1 to 1.05, preferably 1:1 to 1.04, more preferably 1:1 to 1.03. The molar ratio of citric acid to the water-soluble iron salt is 2 to 2.4:1, preferably 2.1 to 2.3:1, more preferably 2.2 to 2.3:1.
[0031] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 1), under stirring, the water-soluble iron salt and citric acid are sequentially added to the samarium salt aqueous solution, and after the addition, stirring is continued for 1 to 3 h to obtain an initial reactant.
[0032] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 3), the washing solvent is selected from at least one of methanol, ethanol, isopropanol, acetone and water.
[0033] In the present invention, preferably, when washing the separated solid, the washing solvent is selected from one of methanol, ethanol, isopropanol, acetone and water, more preferably ethanol. For example, it can be anhydrous ethanol.
[0034] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 3), the drying temperature is 55 to 100 °C and the drying time is 6 to 18 h. This is beneficial to obtaining samarium ferrite powder with a specific morphology.
[0035] In the present invention, the drying temperature can be 55 to 100 °C, preferably 65 to 90 °C, more preferably 75 to 85 °C. The drying time can be 6 to 18 h, preferably 8 to 15 h. Drying can be carried out in a common oven or a vacuum drying oven.
[0036] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 4), the inert atmosphere is an atmosphere formed by nitrogen or an inert gas, wherein the inert gas is selected from at least one of helium, argon, krypton and xenon.
[0037] According to a specific embodiment of the present invention, the inert atmosphere is an atmosphere formed by argon.
[0038] According to the method for preparing samarium ferrite powder of the present invention, preferably, in step 4), the calcination temperature is 750 - 850 °C, and the calcination time is 1 - 3 h.
[0039] According to a specific embodiment of the present invention, the precursor is calcined at 800 - 850 °C for 1 - 2 h in an argon atmosphere to obtain samarium ferrite powder. This is conducive to obtaining samarium ferrite powder with a specific morphology and particle size.
[0040] On the other hand, the present invention also provides a samarium ferrite powder, which is prepared according to the preparation method described above. The particle size of the samarium ferrite powder is 2 - 3 μm, and the morphology is basically spherical. The obtained samarium ferrite powder has a narrow particle size distribution and good sphericity. The samarium ferrite powder with a generally spherical morphology obtained in the present invention can be used in the fields of magnetic materials, rare earth polishing, catalysis, sensing, etc.
[0041] The samarium ferrite powder prepared by the preparation method of the present invention has good sphericity, a particle size of 2 - 3 μm, and a narrow particle size distribution. In addition, the preparation method of the present invention does not add any surfactants, does not add alcohols including ethylene glycol, etc., and only uses water as a solvent, with lower cost. The process conditions of the preparation method of the present invention are not complex, and perovskite-type samarium ferrite powder with controllable morphology can be obtained, which has important scientific significance and application value. Description of the Drawings
[0042] Figure 1 It is the XRD pattern of the samarium ferrite powder which is the product of Example 1.
[0043] Figure 2 It is the SEM image of the samarium ferrite powder which is the product of Example 1.
[0044] Figure 3 It is the SEM image of the samarium ferrite powder which is the product of Comparative Example 1. Detailed Description of the Embodiments
[0045] The following introduces the test methods used in the following examples and comparative examples:
[0046] XRD: Tested using an X'Pert PRO X-ray diffractometer.
[0047] SEM: Tested using a ZEISS Sigma 500 field emission scanning electron microscope.
[0048] In the following examples and comparative examples, the citric acid used does not contain crystal water.
[0049] Example 1
[0050] Dissolve 0.447 g (0.001 mol) of samarium nitrate hexahydrate in 40 mL of deionized water, stir and disperse for 10 min to obtain an aqueous solution of samarium nitrate.
[0051] With stirring, add 0.4041 g (0.001 mol) of ferric nitrate nonahydrate to the aqueous solution of samarium nitrate. After dissolution, add 0.4202 g (0.0022 mol) of citric acid and continue stirring for 2 h to obtain the initial reactant.
[0052] Place the initial reactant in a sealed autoclave and carry out hydrothermal reaction at 180 °C for 10 h to obtain the intermediate reactant.
[0053] After cooling, centrifuge the intermediate reactant, wash the centrifuged solid with ethanol, and dry the washed solid at 80 °C for 8 h to obtain the precursor.
[0054] Calcine the precursor in an argon atmosphere at 800 °C for 1 h. After cooling, grind the calcined product to obtain samarium ferrite powder.
[0055] The XRD results of the samarium ferrite powder obtained in this example are shown in Figure 1 , and the SEM results are shown in Figure 2 . From Figure 1 it can be seen that the characteristic peaks of the obtained samarium ferrite powder are very sharp, indicating that the crystallinity of the samarium ferrite powder is good, and the diffraction peaks of XRD correspond to the diffraction peaks of SmFeO3 identified by the standard PDF card JCPDS No. 34-0394.
[0056] From Figure 2 it can be seen that the obtained samarium ferrite powder has good sphericity, fewer broken spherical particles, a higher ball forming rate, a particle size of 2 - 3 μm, and a narrow particle size distribution.
[0057] Example 2
[0058] Dissolve 0.447 g (0.001 mol) of samarium nitrate hexahydrate in 40 mL of deionized water, stir and disperse for 10 min to obtain an aqueous solution of samarium nitrate.
[0059] With stirring, add 0.4041 g (0.001 mol) of ferric nitrate nonahydrate to the aqueous solution of samarium nitrate. After dissolution, add 0.4202 g (0.0022 mol) of citric acid and continue stirring for 2 h to obtain the initial reactant.
[0060] Place the initial reactant in a sealed autoclave and carry out hydrothermal reaction at 200 °C for 10 h to obtain the intermediate reactant.
[0061] After cooling, centrifuge the intermediate reactant, wash the centrifuged solid with ethanol, and dry the washed solid at 80 °C for 8 h to obtain the precursor.
[0062] The precursor was calcined at 800° C. for 2 h in an argon atmosphere, and the calcined product was ground after cooling to obtain samarium ferrite powder.
[0063] The test results are basically similar to those of Example 1. The samarium ferrite powder obtained in this example has good sphericity, a particle size of 2 to 3 μm, and a narrow particle size distribution.
[0064] Comparative Example 1
[0065] 0.447 g (0.001 mol) of samarium nitrate hexahydrate was dissolved in 40 mL of deionized water and stirred for 10 min to obtain a samarium nitrate aqueous solution.
[0066] Under stirring, 0.5123 g (0.0013 mol) of ferric nitrate nonahydrate was added to the samarium nitrate aqueous solution. After dissolution, 0.4202 g (0.0022 mol) of citric acid was added and stirring was continued for 2 h to obtain the initial reactant.
[0067] The initial reactants were placed in a sealed reactor and subjected to hydrothermal reaction at 180° C. for 10 h to obtain an intermediate reactant.
[0068] After cooling, the intermediate reactant is centrifuged, the solid obtained by centrifugation is washed with ethanol, and the washed solid is dried at 80° C. for 8 h to obtain a precursor.
[0069] The precursor was calcined at 800° C. for 1 h in an argon atmosphere, and the calcined product was ground after cooling to obtain samarium ferrite powder.
[0070] The SEM results of the samarium ferrite powder obtained in this comparative example are shown in Figure 3 .Depend on Figure 3 and Figure 2 It can be seen that compared with Example 1, the spheroidization rate of the samarium ferrite powder obtained in this comparative example is lower, the sphericity is worse, the particle size distribution is wider, and the particle size is relatively uneven.
[0071] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be thought of by those skilled in the art shall fall within the scope of the present invention.
Claims
1. A method for preparing samarium ferrite powder, characterized in that: The following steps are involved: 1) Mixing and stirring a samarium salt aqueous solution, a water-soluble iron salt and citric acid for 1 to 3 hours to obtain an initial reactant; 2) hydrothermally reacting the initial reactants at 180-200° C. for 6-15 hours to obtain an intermediate reactant; 3) separating the intermediate reactant from the solid and liquid, washing the separated solid, and drying the washed solid to obtain a precursor; 4) calcining the precursor in an inert atmosphere at 700-900° C. for 1-5 hours to obtain samarium ferrite powder.
2. The preparation method according to claim 1, characterized in that: In step 1), the molar concentration of the samarium salt aqueous solution is 0.005-0.5 mol / L; the samarium salt in the samarium salt aqueous solution is selected from at least one of samarium nitrate, samarium chloride, samarium sulfate and samarium acetate.
3. The preparation method according to claim 1, characterized in that: In step 1), the water-soluble iron salt is selected from at least one of ferric chloride, ferric sulfate and ferric nitrate.
4. The preparation method according to claim 1, characterized in that: In step 1), the molar ratio of the iron element in the water-soluble iron salt to the samarium element in the samarium salt aqueous solution is 1:1-1.05; the molar ratio of citric acid to the water-soluble iron salt is 2-2.4:
1.
5. The preparation method according to claim 1, characterized in that: In step 1), water-soluble iron salt and citric acid are sequentially added to the samarium salt aqueous solution under stirring, and stirring is continued for 1 to 3 hours after the addition to obtain an initial reactant.
6. The preparation method according to claim 1, characterized in that: In step 3), the washing solvent is selected from at least one of methanol, ethanol, isopropanol, acetone and water.
7. The preparation method according to claim 1, characterized in that: In step 3), the drying temperature is 55 to 100° C. and the drying time is 6 to 18 hours.
8. The preparation method according to claim 1, characterized in that: In step 4), the inert atmosphere is an atmosphere formed by nitrogen or an inert gas, wherein the inert gas is selected from at least one of helium, argon, krypton and xenon.
9. The preparation method according to claim 1, characterized in that: In step 4), the calcination temperature is 750-850° C. and the calcination time is 1-3 hours.
10. A samarium ferrite powder, characterized in that: The samarium ferrite powder is prepared according to the preparation method according to any one of claims 1 to 9, and the particle size of the samarium ferrite powder is 2 to 3 μm, and the morphology is basically spherical.