Method for preparing rare earth co-doped ferrite

Abstract

The invention relates to a method for preparing rare earth co-doped ferrite, and belongs to the technical field of magnetic materials. The rare earth co-doped ferrite is prepared from iron nitrate nonahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, cerium nitrate hexahydrate, lithium chloride, nickel chloride and other materials. The rare earth co-doped ferrite prepared by the method disclosed by the invention is excellent in overall magnetic performance, and the coercive force and magnetization intensity of the ferrite can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic materials and relates to a method for preparing rare earth co-doped ferrite. Background Art

[0002] Ferrite is a ceramic magnetic material with high resistance and high magnetization strength. It is widely used in electronic communication equipment, microwave absorbers, magnetic storage, magnetic recording equipment, and computers. Ferrite is composed of iron oxide and divalent metal ion oxide. Common M can be copper, zinc, nickel, manganese, cobalt, barium and strontium. At the same time, Fe in ferrite 3+ Ions can be replaced by other ions. Ion substitution, preparation methods and synthesis conditions can all lead to changes in the properties of ferrite materials.

[0003] In order to improve the performance of ferrite, measures can be taken to improve its microstructure, control its chemical composition, grain size and morphology, etc. Therefore, how to prepare ferrite with high purity, ultrafine, uniform distribution and excellent magnetic properties has become a hot topic in recent years. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing rare earth co-doped ferrite. The rare earth co-doped ferrite prepared by the method of the present invention has good overall magnetic properties and the preparation method is simple.

[0005] The present invention adopts the following technical solutions to achieve the above purpose:

[0006] A method for preparing rare earth co-doped ferrite, specifically comprising the following steps:

[0007] Step 1, adding ferric nitrate nonahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and cerium nitrate hexahydrate to water, stirring at 50-60° C. for 1.5-2 hours, then adding citric acid, continuing stirring at 50-60° C. for 15-20 minutes to obtain a mixed solution; adding ammonia solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0-7.5, heating to 70-80° C., stirring at 50-60° C. until the mixed solution is in a sol state, and then drying to obtain a gel; sintering the gel, cooling, and grinding to obtain a primary product;

[0008] Step 2, dissolving lithium chloride and nickel chloride in water, adjusting the alcohol content to 50-60%, stirring at 50-60° C. for 10-20 minutes, adding tributyl phosphate, and continuing to stir at this temperature for 40-60 minutes to obtain a mixture; adding ammonia solution dropwise to the mixture until the pH value of the mixture reaches 7.5-8.0, adding sodium alginate and the initial product obtained in step 1, stirring at this temperature until it becomes viscous, drying, and grinding;

[0009] Step 3, after grinding, pressing and forming to obtain a blank; sintering and cooling the blank to obtain rare earth co-doped ferrite.

[0010] Furthermore, the usage amounts of the components in step 1 are 200-230 parts by weight of ferric nitrate nonahydrate, 15-25 parts by weight of zinc nitrate hexahydrate, 30-40 parts by weight of cobalt nitrate hexahydrate, 8-10 parts by weight of cerium nitrate hexahydrate, 800-1000 parts by weight of water, and 90-100 parts by weight of citric acid.

[0011] Furthermore, the aqueous ammonia solution in step 1 is an aqueous ammonia solution with a mass concentration of 25-30%.

[0012] Furthermore, the usage of each component in step 2 is 3-5 parts by weight of lithium chloride, 10-15 parts by weight of nickel chloride, 100-120 parts by weight of water, 5-8 parts by weight of tributyl phosphate, 10-12 parts by weight of sodium alginate, and 200-300 parts by weight of the primary product.

[0013] Furthermore, the sintering process in step 1 is: heating to 200-300° C. at a rate of 10° C. / min and keeping the temperature for 1.5-2 h.

[0014] Furthermore, the sintering process in step 3 is: heating to 500-600°C at a rate of 10°C / min and keeping warm for 1-1.5h, and then heating to 900-1000°C at a rate of 10°C / min and keeping warm for 1.5-2h.

[0015] Furthermore, the grinding method in step 1 is dry ball milling, and the speed of the ball mill is 100-150r / min.

[0016] Furthermore, the grinding method in step 2 is dry ball milling, and the speed of the ball mill is 100-150r / min.

[0017] The present invention has the following beneficial effects:

[0018] In the preparation process of the rare earth co-doped ferrite of the present invention, Ce element is doped. 3+ Replace Fe 3+ After entering the lattice, it causes the increase of magnetocrystalline anisotropy. At the same time, a small amount of Ce 3+After being oxidized to generate CeO2, it is distributed on the grain boundary to produce a pinning effect, which hinders the displacement of the domain wall and increases the coercive force of the ferrite. However, due to the presence of a small amount of CeO2, the grain size of the ferrite will be reduced, resulting in a decrease in the saturation magnetization. To overcome this defect, the preparation process is optimized in the present invention. After preparing the primary ferrite product, a composite containing lithium chloride and nickel chloride is added. During the preparation of the composite, tributyl phosphate, sodium alginate and other ingredients are added to avoid agglomeration, so that the grains are evenly distributed. The prepared ferrite can improve the coercive force while also improving the saturation magnetization and the residual magnetization, thereby increasing the magnetic properties of the ferrite as a whole. DETAILED DESCRIPTION

[0019] The present invention is further explained below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications to the present invention by those skilled in the art all fall within the scope of protection of the claims of this application.

[0020] Example 1

[0021] Step 1, add 200g of ferric nitrate nonahydrate, 25g of zinc nitrate hexahydrate, 30g of cobalt nitrate hexahydrate, and 8g of cerium nitrate hexahydrate to 1000g of water, keep warm and stir for 1.5h in a water bath at 60°C, then add 90g of citric acid, continue to keep warm and stir for 20min to obtain a mixed solution; add a 30% ammonia solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.5, heat the water bath to 80°C, keep warm and stir until the mixed solution is in a sol state, and then dry it in an environment of 200°C to obtain a gel; place the gel in a resistance furnace, heat it to 300°C at a rate of 10°C / min, keep warm and sinter for 1.5h, cool, discharge, place it in a ball mill, and perform dry spheroidal graphite at 150r / min to obtain a primary product;

[0022] Step 2, dissolving 3g of lithium chloride and 15g of nickel chloride in 120g of water, adjusting the alcohol content to 60%, stirring in a 50°C water bath for 20min, adding 5g of tributyl phosphate, and continuing to stir in a 40min heat preservation to obtain a mixture; adding an ammonia solution dropwise to the mixture until the pH value of the mixture reaches 8.0, adding 10g of sodium alginate and 300g of the initial product obtained in step 1, stirring in a viscous state, drying in a 200°C environment, placing in a ball mill, and performing dry spherical graphite at 150r / min;

[0023] Step 3, after ball milling, press and form to obtain a blank; place the blank in a resistance furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 1 hour, then heat it to 1000°C at a rate of 10°C / min and keep it warm for 1.5 hours, cool it, and obtain rare earth co-doped ferrite.

[0024] Example 2

[0025] Step 1, adding 230g of ferric nitrate nonahydrate, 15g of zinc nitrate hexahydrate, 40g of cobalt nitrate hexahydrate, and 10g of cerium nitrate hexahydrate to 800g of water, stirring under the condition of 50°C water bath for 2h, then adding 100g of citric acid, and continuing to stir under the condition of stirring ...

[0026] Step 2, dissolving 5g of lithium chloride and 10g of nickel chloride in 100g of water, adjusting the alcohol content to 50%, stirring in a water bath at 60°C for 10min, adding 8g of tributyl phosphate, and continuing stirring in a water bath at 60°C for 60min to obtain a mixture; adding an ammonia solution dropwise to the mixture until the pH value of the mixture reaches 7.5, adding 12g of sodium alginate and 200g of the initial product obtained in step 1, stirring in a water bath at 200°C until the mixture becomes viscous, drying in a ball mill, and performing dry spherical graphite at 100r / min;

[0027] Step 3, after ball milling, press and form to obtain a blank; place the blank in a resistance furnace, heat it to 500°C at a rate of 10°C / min and keep it warm for 1.5h, then heat it to 900°C at a rate of 10°C / min and keep it warm for 2h, cool it, and obtain rare earth co-doped ferrite.

[0028] Example 3

[0029] Step 1, add 210g of ferric nitrate nonahydrate, 20g of zinc nitrate hexahydrate, 35g of cobalt nitrate hexahydrate, and 9g of cerium nitrate hexahydrate to 900g of water, keep warm and stir for 1.5h in a water bath at 60°C, then add 100g of citric acid, continue to keep warm and stir for 20min to obtain a mixed solution; add a 30% ammonia solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, heat the water bath to 80°C, keep warm and stir until the mixed solution is in a sol state, and then place it in a 200°C environment to dry to obtain a gel; place the gel in a resistance furnace, heat it to 300°C at a rate of 10°C / min, keep warm and sinter for 1.5h, cool, discharge, place it in a ball mill, and perform dry spheroidal graphite at 150r / min to obtain a primary product;

[0030] Step 2, dissolving 4g of lithium chloride and 13g of nickel chloride in 110g of water, adjusting the alcohol content to 55%, stirring in a water bath at 60°C for 15min, adding 7g of tributyl phosphate, and continuing stirring in a water bath at 60°C for 50min to obtain a mixture; adding an ammonia solution dropwise to the mixture until the pH value of the mixture reaches 8.0, adding 11g of sodium alginate and 250g of the initial product obtained in step 1, stirring in a water bath at 200°C until the mixture becomes viscous, drying in a ball mill, and performing dry spherical graphite milling at 150r / min;

[0031] Step 3, after ball milling, press and form to obtain a blank; place the blank in a resistance furnace, heat it to 600°C at a rate of 10°C / min and keep it warm for 1 hour, then heat it to 900°C at a rate of 10°C / min and keep it warm for 2 hours, cool it, and obtain rare earth co-doped ferrite.

[0032] Comparative Example 1

[0033] 230 g of ferric nitrate nonahydrate, 15 g of zinc nitrate hexahydrate, 40 g of cobalt nitrate hexahydrate and 10 g of cerium nitrate hexahydrate are added to 800 g of water, and the mixture is stirred in a water bath at 50° C. for 2 h, and then 100 g of citric acid is added, and the mixture is stirred in a water bath at 50° C. for 15 min to obtain a mixed solution; a 25% ammonia solution is added dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, the mixture is heated to 70° C. in a water bath, stirred in a water bath until the mixture is in a sol state, and then dried in an environment of 200° C. to obtain a gel; the gel is placed in a resistance furnace, heated to 900° C. at a rate of 10° C. / min, and sintered in a water bath at 900° C. for 2 h, cooled, and discharged to obtain a rare earth co-doped ferrite.

[0034] Comparative Example 2

[0035] Step 1, adding 230g of ferric nitrate nonahydrate, 15g of zinc nitrate hexahydrate, 40g of cobalt nitrate hexahydrate, and 10g of cerium nitrate hexahydrate to 800g of water, stirring under the condition of 50°C water bath for 2h, then adding 100g of citric acid, and continuing to stir under the condition of stirring ...

[0036] Step 2, dissolving 15g of nickel chloride in 100g of water, adjusting the alcohol content to 50%, stirring in a 60°C water bath for 10min, adding 8g of tributyl phosphate, and continuing to stir in a 60min bath to obtain a mixture; adding 200g of the initial product obtained in step 1 to the mixture, stirring in a viscous state, drying in a 200°C environment, placing in a ball mill, and performing dry spherical graphite at 100r / min;

[0037] Step 3, after ball milling, press and form to obtain a blank; place the blank in a resistance furnace, heat it to 500°C at a rate of 10°C / min and keep it warm for 1.5h, then heat it to 900°C at a rate of 10°C / min and keep it warm for 2h, cool it, and obtain rare earth co-doped ferrite.

[0038] Comparative Example 3

[0039] 230g of ferric nitrate nonahydrate, 15g of zinc nitrate hexahydrate, 40g of cobalt nitrate hexahydrate, 10g of cerium nitrate hexahydrate, 4g of lithium chloride and 13g of nickel chloride are added to 800g of water, and the mixture is stirred in a water bath at 50°C for 2h, and then 100g of citric acid and 12g of sodium alginate are added, and the mixture is stirred in a water bath at a temperature of 15°C for 15min to obtain a mixed solution; an ammonia solution with a mass concentration of 25% is added dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, the mixture is heated to 70°C in a water bath, stirred in a water bath until the mixture is in a sol state, and then dried in an environment of 200°C to obtain a gel; the gel is placed in a resistance furnace, heated to 500°C at a rate of 10°C / min and kept warm for 1.5h, and then heated to 900°C at a rate of 10°C / min and kept warm for 2h, cooled, and a rare earth co-doped ferrite is obtained.

[0040] Performance Testing

[0041] With reference to existing literature, the rare earth co-doped ferrites prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to comprehensive magnetic property testing, and the results are shown in Table 1 below:

[0042] From the results in Table 1, it can be seen that the overall magnetic properties of the rare earth co-doped ferrites prepared by the preparation methods of Examples 1 to 3 of the present invention are relatively excellent; indicators such as coercive force and residual magnetization intensity have been significantly improved, and the magnetic properties are significantly better than those of the traditional preparation method (Comparative Example 1); Lithium chloride and sodium alginate are not used in Comparative Example 2, and the preparation process in Comparative Example 3 is different. The ferrite obtained has better performance than Comparative Example 1, but compared with the present invention, the magnetic properties are poor.

[0043] Table 1 Room temperature magnetic properties parameters of rare earth co-doped ferrites

[0044]

Claims

1. A method for preparing rare earth co-doped ferrite, characterized in that: The following steps are involved: Step 1, adding ferric nitrate nonahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and cerium nitrate hexahydrate to water, stirring at 50-60° C. for 1.5-2 hours, then adding citric acid, continuing stirring at 50-60° C. for 15-20 minutes to obtain a mixed solution; adding ammonia solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0-7.5, heating to 70-80° C., stirring at 50-60° C. until the mixed solution is in a sol state, and then drying to obtain a gel; sintering the gel, cooling, and grinding to obtain a primary product; Step 2, dissolving lithium chloride and nickel chloride in water, adjusting the alcohol content to 50-60%, stirring at 50-60° C. for 10-20 minutes, adding tributyl phosphate, and continuing to stir at this temperature for 40-60 minutes to obtain a mixture; adding ammonia solution dropwise to the mixture until the pH value of the mixture reaches 7.5-8.0, adding sodium alginate and the initial product obtained in step 1, stirring at this temperature until it becomes viscous, drying, and grinding; Step 3, after grinding, pressing and forming to obtain a blank; sintering and cooling the blank to obtain rare earth co-doped ferrite.

2. The method according to claim 1, characterized in that The usage amounts of the components in step 1 are respectively 200-230 parts by weight of ferric nitrate nonahydrate, 15-25 parts by weight of zinc nitrate hexahydrate, 30-40 parts by weight of cobalt nitrate hexahydrate, 8-10 parts by weight of cerium nitrate hexahydrate, 800-1000 parts by weight of water, and 90-100 parts by weight of citric acid.

3. The method according to claim 1, characterized in that The ammonia solution in step 1 is an ammonia solution with a mass concentration of 25-30%.

4. The method according to claim 1, characterized in that The usage of each component in step 2 is 3-5 parts by weight of lithium chloride, 10-15 parts by weight of nickel chloride, 100-120 parts by weight of water, 5-8 parts by weight of tributyl phosphate, 10-12 parts by weight of sodium alginate, and 200-300 parts by weight of the primary product.

5. The method according to claim 1, characterized in that The sintering process in step 1 is: heating to 200-300° C. at a rate of 10° C. / min and keeping the temperature for 1.5-2 hours.

6. The method according to claim 1, characterized in that The sintering process in step 3 is: heating to 500-600°C at a rate of 10°C / min and keeping the temperature for 1-1.5h, and then heating to 900-1000°C at a rate of 10°C / min and keeping the temperature for 1.5-2h.

7. The method according to claim 1, characterized in that The grinding method in step 1 is dry ball milling, and the speed of the ball mill is 100-150r / min.

8. The method according to claim 1, characterized in that The grinding method in step 2 is dry ball milling, and the speed of the ball mill is 100-150r / min.

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