A method for preparing rare earth co-doped ferrite

Abstract

The present invention relates to a method for preparing rare earth co-doped ferrite, belonging to the technical field of magnetic materials. The rare earth co-doped ferrite is prepared from materials such as ferric nitrate nonahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, cerium nitrate hexahydrate, lithium chloride, and nickel chloride. The rare earth co-doped ferrite prepared using the method has excellent overall magnetic properties, and can improve the coercivity and magnetization strength of the ferrite.

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 such as improving its microstructure, controlling its chemical composition, grain size and morphology can be taken. Therefore, how to prepare ferrite with high purity, ultrafine, uniform distribution and excellent magnetic properties has become a research hotspot 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-mentioned purpose:

[0006] A method for preparing rare earth co-doped ferrite comprises 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, and continuing stirring at 50-60° C. for 15-20 minutes to obtain a mixed solution; adding an 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, then 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 primary product obtained in step 1, stirring at this temperature until the mixture 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 ammonia solution in step 1 is an 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 hours.

[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 1-1.5 hours, and then heating to 900-1000° C. at a rate of 10° C. / min and keeping warm for 1.5-2 hours.

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

[0016] Furthermore, the grinding method in step 2 is dry ball milling, and the ball mill speed 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 boundaries to produce a pinning effect, which hinders the displacement of domain walls 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 compound containing lithium chloride and nickel chloride is added. During the preparation of the compound, components such as tributyl phosphate and sodium alginate are added to avoid agglomeration and make the grains evenly distributed. The prepared ferrite can improve the coercive force while also improving the saturation magnetization and residual magnetization, thereby increasing the magnetic properties of the ferrite as a whole. DETAILED DESCRIPTION

[0019] The present invention is further illustrated below with reference to 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, modifications of various equivalent forms of the present invention made 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 60°C water bath, then add 90g of citric acid, continue to keep warm and stir for 20min to obtain a mixed solution; add a 30% ammonia aqueous 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 a 200°C environment 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 dry spherical graphite at 150r / min to obtain a primary product;

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

[0023] Step 3: After ball milling, press and form the 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: add 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, keep stirring in a water bath at 50°C for 2h, then add 100g of citric acid, continue keeping stirring for 15min to obtain a mixed solution; add a 25% ammonia aqueous solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, heat the water bath to 70°C, keep stirring 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 200°C at a rate of 10°C / min, keep it warm for 2h, cool it, discharge it, place it in a ball mill, and dry spherical graphite at 100r / min to obtain a primary product;

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

[0027] Step 3: After ball milling, press and form the 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 1.5 hours, 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.

[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 60°C water bath, then add 100g of citric acid, continue to keep warm and stir for 20min to obtain a mixed solution; add a 30% ammonia aqueous 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 dry it in a 200°C environment 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 dry spherical graphite at 150r / min to obtain a primary product;

[0030] Step 2: dissolving 4 g of lithium chloride and 13 g of nickel chloride in 110 g of water, adjusting the alcohol content to 55%, stirring in a 60° C. water bath for 15 min, adding 7 g of tributyl phosphate, and continuing to stir in a 50 min 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 11 g of sodium alginate and 250 g of the primary product obtained in step 1, stirring in a viscous state, drying in a 200° C. environment, and placing in a ball mill for dry spherical graphite at 150 r / min;

[0031] Step 3: After ball milling, press and form the 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 aqueous solution is added dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, the water bath is heated to 70° C., and the mixture is stirred in a water bath at 70° C. until the mixture is in a sol state, and then dried in an environment at 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 heat preservation state for 2 h, cooled, and discharged to obtain a rare earth co-doped ferrite.

[0034] Comparative Example 2

[0035] Step 1: add 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, keep stirring in a water bath at 50°C for 2h, then add 100g of citric acid, continue keeping stirring for 15min to obtain a mixed solution; add a 25% ammonia aqueous solution dropwise to the mixed solution until the pH value of the mixed solution reaches 7.0, heat the water bath to 70°C, keep stirring 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 200°C at a rate of 10°C / min, keep it warm for 2h, cool it, discharge it, place it in a ball mill, and dry spherical graphite at 100r / min to obtain a primary product;

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

[0037] Step 3: After ball milling, press and form the 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 1.5 hours, 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.

[0038] Comparative Example 3

[0039] 230 g of ferric nitrate nonahydrate, 15 g of zinc nitrate hexahydrate, 40 g of cobalt nitrate hexahydrate, 10 g of cerium nitrate hexahydrate, 4 g of lithium chloride, and 13 g of nickel chloride 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 and 12 g of sodium alginate are added, and the mixture is stirred in a water bath at 50° C. for 15 min to obtain a mixed solution; a 25% ammonia aqueous 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 at 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 1.5 h, and then heated to 900° C. at a rate of 10° C. / min, and kept warm for 2 h, and cooled to obtain a rare earth co-doped ferrite.

[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 and 2 were subjected to comprehensive magnetic property testing. The results are shown in Table 1 below:

[0042] As can be seen from the results in Table 1, 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 coercivity and residual magnetization are significantly improved, and the magnetic properties are significantly better than those of the traditional preparation method (Comparative Example 1); in Comparative Example 2, no lithium chloride or sodium alginate is used, and the preparation process in Comparative Example 3 is different. The ferrite obtained has better performance than that of Comparative Example 1, but its magnetic properties are worse than those of the present invention.

[0043] Table 1 Room temperature magnetic properties 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, and continuing stirring at 50-60° C. for 15-20 minutes to obtain a mixed solution; adding an 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, then 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 reaches 7.5-8.0, adding sodium alginate and the primary product obtained in step 1, stirring at this temperature until the mixture 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, wherein 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.

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

4. The method according to claim 1, wherein 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, wherein 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, wherein The sintering process in step 3 is: heating to 500-600° C. at a rate of 10° C. / min and keeping warm for 1-1.5 hours, then heating to 900-1000° C. at a rate of 10° C. / min and keeping warm for 1.5-2 hours.

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

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

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