A praseodymium-doped nickel-zinc-cobalt ferrite and its preparation method

Abstract

The present invention belongs to the technical field of soft ferrite materials, and specifically relates to a praseodymium-doped nickel-zinc-cobalt ferrite and a preparation method thereof, wherein the molecular formula is: Ni m Zn n Co 1‑m‑n Pr x Fe 2‑x O4, wherein 0<x≤0.1, 0.5≤m<1, 0<n<0.5, is prepared by combining sol-gel self-propagating combustion method and microwave sintering; in addition, Pr 3+ Replace Fe 3+ To improve the magnetic and electrical properties of the material, its preparation process is simple and pollution-free. The resulting material also achieves a high cutoff frequency, a high DC resistivity, and a low dielectric loss. It can provide a reference for the development of high-frequency miniaturized electronic equipment and is expected to enhance my country's core competitiveness in the miniaturization and integration of high-frequency and even ultra-high-frequency electronic devices.

Description

Technical Field

[0001] The invention belongs to the technical field of soft ferrite materials, and particularly relates to praseodymium-doped nickel-zinc-cobalt ferrite and a preparation method thereof. Background Art

[0002] With the rapid development of electronic information, Internet, biomedicine and other industries, the requirements for miniaturization and integration of electronic equipment are becoming increasingly higher, and it is necessary to develop higher performance materials to meet the needs of contemporary electronic components. Ferrite ceramics have good chemical stability, high resistivity and excellent magnetic properties. They are an important magnetic material and are widely used in many electromagnetic devices. The main component of ferrite is metal oxide containing Fe3O4, which is mainly divided into soft ferrite, permanent ferrite and gyromagnetic ferrite. NiZnCo ferrite is a very representative spinel soft ferrite with excellent electromagnetic properties, including high Curie temperature (θ f ), high resistivity (ρ), low coercivity (H c ), high saturation magnetization (M s ), low dielectric loss tanδ and high initial permeability μ i Therefore, NiZnCo ferrite is widely used in the preparation of various electronic components, including high-frequency soft magnetic devices, radio frequency broadband devices and anti-interference devices.

[0003] However, with the rapid development of modern industry and the emergence of many emerging functional materials, electronic components have become highly integrated. This has necessitated the exploration of new preparation processes, novel ion doping and substitution, and the integration of new functional materials with NiZnCo ferrites to meet the specific operating conditions of electronic components. Therefore, improving the electromagnetic properties of ferrites remains a major technical challenge in device applications. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a praseodymium-doped nickel-zinc-cobalt ferrite prepared by a sol-gel self-propagating combustion method and microwave sintering.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] In one aspect, the present invention provides a praseodymium-doped nickel-zinc-cobalt ferrite, wherein the molecular formula of the praseodymium-doped nickel-zinc-cobalt ferrite is: Ni m Zn n Co 1-m-n Pr x Fe 2-x O4, where 0<x≤0.1, 0.5≤m<1, 0<n<0.5.

[0007] In some embodiments, the molecular formula of the praseodymium-doped nickel-zinc-cobalt ferrite is: Ni 0.55 Zn 0.3 Co 0.15 Pr x Fe 2- x O4, where 0.025≤x≤0.1, x=0.025, 0.05, 0.075 or 0.1.

[0008] In another aspect, the present invention provides a method for preparing praseodymium-doped nickel-zinc-cobalt ferrite, comprising the following steps:

[0009] a. Prepare a wet gel precursor: Mix nickel salt, zinc salt, cobalt salt, iron salt, praseodymium salt and deionized water, add citric acid after dissolving, and stir at 70-90°C for 2-4 hours while controlling the pH value of the reaction system to 6.5-7.5 to obtain a wet gel precursor;

[0010] b. Preparing a dry gel precursor: drying the wet gel precursor obtained in step a to obtain a dry gel precursor;

[0011] c. Self-propagating combustion reaction: heating the dry gel precursor to make it self-propagating combustion into nano-scale powder, and then adding polyvinyl alcohol for granulation;

[0012] d. Blank making: the granulated powder is pressed into blanks;

[0013] e. Microwave sintering: Place the blank in a microwave sintering furnace and sinter it to obtain praseodymium-doped nickel-zinc-cobalt ferrite.

[0014] In some embodiments, in step a, the nickel salt is nickel nitrate, the zinc salt is zinc nitrate, the cobalt salt is cobalt nitrate, the iron salt is iron nitrate, and the praseodymium salt is praseodymium nitrate.

[0015] In some embodiments, in step a, the amount of citric acid added is 2 to 4 times the sum of the amounts of nickel salt, zinc salt, cobalt salt, iron salt and praseodymium salt.

[0016] In some embodiments, in step a, the reaction temperature is 80° C., the reaction is stirred for 4 h, and the pH value of the reaction system is controlled to be 7.

[0017] In some embodiments, in step c, the amount of polyvinyl alcohol added is 6-10 wt% of the weight of the nanopowder.

[0018] In some embodiments, in step d, the pressing pressure is 5-25 MPa, and the pressing time is 0.5-2 min. It should be noted that if the granulated powder is pressed into a round billet, the pressing pressure is 10 MPa and the pressing time is 1 min. If the granulated powder is pressed into a ring billet, the ring pressing pressure is 20 MPa and the pressing time is 1 min.

[0019] In some embodiments, in step e, the blank is sintered at a temperature of 1000-1200° C. and for a time of 1-4 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The praseodymium-doped nickel-zinc-cobalt ferrite of the present invention is based on Ni m Zn n Co 1-m-n Fe2O4 ferrite is used as the basis, and the preparation process adopts the combination of sol-gel self-propagating combustion method and microwave sintering method. 3+ Replace Fe 3+ To improve the magnetic and electrical properties of the material, the preparation process is simple and the process is pollution-free. The resulting material also achieves a high cutoff frequency, a high DC resistivity, and a low dielectric loss. It can provide a reference for the development of high-frequency miniaturized electronic equipment and is expected to enhance my country's core competitiveness in the miniaturization and integration of high-frequency and even ultra-high-frequency electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM morphology of the nickel-zinc-cobalt ferrite prepared in Comparative Example 1 of the present invention;

[0023] Figure 2 This is a SEM morphology of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 1 of the present invention;

[0024] Figure 3 This is an SEM morphology of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 2 of the present invention;

[0025] Figure 4 This is a SEM morphology of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 3 of the present invention;

[0026] Figure 5 This is an SEM morphology of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 4 of the present invention;

[0027] Figure 6 This is the EDS spectrum of nickel-zinc-cobalt ferrite prepared in Comparative Example 1 of the present invention;

[0028] Figure 7This is an EDS spectrum of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 1 of the present invention;

[0029] Figure 8 This is an EDS spectrum of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 2 of the present invention;

[0030] Figure 9 This is an EDS spectrum of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 3 of the present invention;

[0031] Figure 10 This is the EDS spectrum of the praseodymium-doped nickel-zinc-cobalt ferrite prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some of the embodiments of the present disclosure, not all of them. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0033] The praseodymium-doped nickel-zinc-cobalt ferrite of the present invention has the molecular formula: Ni m Zn n Co 1-m-n Pr x Fe 2-x O4, where 0<x≤0.1, 0.5≤m<1, 0<n<0.5.

[0034] The praseodymium-doped nickel-zinc-cobalt ferrite of the present invention is based on Ni m Zn n Co 1-m-n Fe2O4 ferrite is based on Pr 3+ Replace Fe 3+ In order to improve the magnetic and electrical properties of the material, the resulting praseodymium-doped nickel-zinc-cobalt ferrite has a high cutoff frequency, high DC resistivity and low dielectric loss, which can provide a reference for the development of high-frequency miniaturized electronic equipment, and is expected to enhance my country's core competitiveness in the miniaturization and integration of high-frequency and even ultra-high-frequency electronic devices.

[0035] Preferably, m=0.55, n=0.3, that is, the molecular formula of the praseodymium-doped nickel-zinc-cobalt ferrite is: Ni 0.55 Zn 0.3 Co 0.15 Pr x Fe 2-x O4. The study found that when m=0.55, n=0.3, the performance of the material is better than Ni 0.6 Zn 0.35 Co 0.05 Prx Fe 2-x O4、Ni 0.5 Zn 0.3 Co 0.2 Pr x Fe 2-x O4 and others have higher magnetic permeability, high resistivity, low coercivity and low dielectric loss.

[0036] Preferably, 0.025≤x≤0.1.

[0037] As a preferred embodiment, x=0.025, 0.05, 0.075 or 0.1, that is, the molecular formula of the praseodymium-doped nickel-zinc-cobalt ferrite is Ni 0.55 Zn 0.3 Co 0.15 Pr 0.025 Fe 1.975 O4、Ni 0.55 Zn 0.3 Co 0.15 Pr 0.05 Fe 1.95 O4、Ni 0.55 Zn 0.3 Co 0.15 Pr 0.075 Fe 1.925 O4 or Ni 0.55 Zn 0.3 Co 0.15 Pr 0.1 Fe 1.9 O4.

[0038] The present invention also provides a method for preparing the praseodymium-doped nickel-zinc-cobalt ferrite of the present invention.

[0039] The preparation method of praseodymium-doped nickel-zinc-cobalt ferrite of the present invention comprises the following steps:

[0040] a. Preparing a wet gel precursor: nickel salt, zinc salt, cobalt salt, iron salt, praseodymium salt and deionized water are mixed, citric acid is added after dissolving, and the mixture is stirred at 70-90°C for 2-4 hours while controlling the pH value of the reaction system to 6.5-7.5, thereby obtaining a wet gel precursor;

[0041] b. Preparing a dry gel precursor: drying the wet gel precursor to obtain a dry gel precursor;

[0042] c. Self-propagating combustion reaction: heating the dry gel precursor to make it self-propagating combustion into nano-scale powder, and then adding polyvinyl alcohol for granulation;

[0043] d. Blank making: the granulated powder is pressed into blanks;

[0044] e. Microwave sintering: Place the blank in a microwave sintering furnace and sinter at 1000-1200°C for 1-4 hours to obtain praseodymium-doped nickel-zinc-cobalt ferrite.

[0045] The method of the present invention adopts the sol-gel self-propagating combustion method and the microwave sintering method to prepare Ni m Zn n Co 1-m- n Pr x Fe 2-x O4 spinel ferrite material has a simple preparation process and is pollution-free. The obtained material simultaneously obtains a high cutoff frequency, a high DC resistivity and a low dielectric loss.

[0046] The traditional solid-phase method for preparing ferrites requires high sintering temperatures, typically exceeding 1200°C, far exceeding the temperature of microwave sintering and prone to excessive electromagnetic losses. Therefore, the present invention utilizes a preparation method that combines sol-gel self-propagation with microwave sintering, while also preparing the doped ferrite material through ion replacement. This avoids the problems of traditional sintering, such as excessive sintering times and internal thermodynamic inhomogeneity. It effectively leverages the advantages of microwave sintering, including rapid sintering speed, easy modification of the ferrite microstructure (ultrafine grain structure with high strength and toughness), high energy efficiency, selective sintering, and pollution-free operation. This method also enables the preparation of high-performance NiZnCo ferrites, addressing the issues of high coercivity, high dielectric loss, and other key electromagnetic performance degradation issues associated with ferrites prepared by traditional sintering.

[0047] The purpose of step a is to obtain a wet gel precursor. Nickel salt, zinc salt, cobalt salt, iron salt, praseodymium salt and deionized water are mixed, citric acid is added after dissolution, and the mixture is stirred at 70-90°C for 2-4 hours. At the same time, the pH value of the reaction system is controlled at 6.5-7.5 to obtain a wet gel precursor.

[0048] The ratio of nickel salt, zinc salt, cobalt salt, iron salt and praseodymium salt is determined by the molecular formula of the target product. 0.55 Zn 0.3 Co 0.15 Pr 0.025 Fe 1.975 O4, the molar ratio of the metal elements in nickel salt, zinc salt, cobalt salt, iron salt and praseodymium salt is 0.55: 0.3: 0.15: 0.025: 1.975, that is, in molar ratio, Ni: Zn: Co: Pr: Fe=0.55: 0.3: 0.15: 0.025: 1.975.

[0049] Commonly used water-soluble metal salts are suitable for the present invention. Preferably, the nickel salt is nickel nitrate, the zinc salt is zinc nitrate, the cobalt salt is cobalt nitrate, the iron salt is iron nitrate, and the praseodymium salt is praseodymium nitrate.

[0050] When nickel salt, zinc salt, cobalt salt, iron salt, praseodymium salt and deionized water are mixed, there is no requirement for the order in which the metal salts are added, as long as all the metal salts are dissolved in water after mixing.

[0051] In order to speed up the mixing and dissolution rate, stirring can be used during mixing.

[0052] The present invention does not require the amount of deionized water added during mixing, as long as it can dissolve the added metal salts. For example, the sum of the concentrations of nickel salt, zinc salt, cobalt salt, iron salt, and praseodymium salt is 0.15 mol / L.

[0053] After the above metal salts are mixed and dissolved in deionized water, citric acid is added. Preferably, the amount of citric acid added is 2 to 4 times the total amount of the nickel salt, zinc salt, cobalt salt, iron salt, and praseodymium salt. As a preferred embodiment, the amount of citric acid added is 3 times the total amount of the nickel salt, zinc salt, cobalt salt, iron salt, and praseodymium salt.

[0054] After adding citric acid, the temperature is raised and stirred at 70-90° C. for 2-4 h, while the pH value of the reaction system is controlled to be 6.5-7.5. The methods commonly used in the art for adjusting pH are applicable to the present invention. For example, the pH value of the system can be maintained by gradually adding ammonia water.

[0055] As a preferred embodiment, in step a, the reaction is stirred at 80° C. for 4 h, and the pH value of the reaction system is controlled to be 7.

[0056] The purpose of step b is to obtain a xerogel precursor. This process simply involves removing moisture from the wet gel precursor obtained in step a. Conventional methods for removing moisture can be used, such as oven drying, air drying, or air drying. Preferably, drying is performed at 80°C.

[0057] Step c: The dry gel precursor is heated to cause self-propagating combustion to form nano-sized powder, which is then granulated by adding polyvinyl alcohol.

[0058] The heating methods commonly used in the art are applicable to the present invention. Preferably, an alcohol burner is used to heat the xerogel precursor.

[0059] After the self-propagation reaction, the dry gel precursor becomes a nano-scale powder, which is mixed with polyvinyl alcohol for granulation. Preferably, the amount of polyvinyl alcohol added is 6 to 10 wt% of the weight of the nano-scale powder.

[0060] In step d, the pellets are formed using any commonly used pressing methods in the art. Preferably, the pressure for pellet pressing is 5-15 MPa, and the pressure for ring pressing is 15-25 MPa, with a pressing time of 0.5-2 minutes. More preferably, the pressure for pellet pressing is 10 MPa, with a pressing time of 1 minute; and the pressure for ring pressing is 20 MPa, with a pressing time of 1 minute. Pressing can be performed using commonly used equipment, such as a manual hydraulic press.

[0061] Step e is a microwave sintering step, in which the blank is placed in a microwave sintering furnace and sintered at 1000-1200° C. for 1-4 hours to obtain praseodymium-doped nickel-zinc-cobalt ferrite.

[0062] As a preferred solution, in step e, the blank is sintered at 1150° C. for 4 hours.

[0063] The specific embodiments of the present invention are further described below in conjunction with the examples, but the present invention is not limited to the scope of the examples. The purity of the raw materials Ni(NO3)2·6H2O, Zn(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and Pr(NO3)3·6H2O used in the examples is greater than 99wt%.

[0064] Example 1

[0065] 1. According to Ni 0.55 Zn 0.3 Co 0.15 Pr 0.025 Fe 1.975 The O4 component was prepared into a 1 L solution with a concentration of 0.3 mol / L. 13.6815 g of Ni(NO3)2·6H2O, 7.5575 g of Zn(NO3)2·6H2O, 3.6967 g of Co(NO3)2·6H2O, 67.9094 g of Fe(NO3)3·9H2O, and 0.9209 g of Pr(NO3)3·6H2O were weighed, totaling 93.766 g of powder. All of the above powders were added to a beaker, and deionized water was added to mix and stir for 30 minutes until all nitrates were dissolved. Citric acid was then added at a molar ratio of 3:1 to nitrates.

[0066] 2. Stir the prepared solution with a constant temperature magnetic stirrer at 80°C for 4 h while gradually adding ammonia water to maintain the pH at 7 to obtain a wet gel precursor.

[0067] 3. Place the obtained wet gel precursor in an oven and dry it at 80°C to obtain a dry gel precursor;

[0068] 4. Heating the xerogel precursor to cause self-propagating combustion into nano-sized powders, followed by the addition of 10 wt% polyvinyl alcohol for granulation;

[0069] 5. Add the granulated powder into the mold and press into discs (Ø10 mm × h2 mm, 10 MPa) and rings (Ø18 mm × h2 mm, 20 MPa) on a manual hydraulic press, maintaining the pressure for 1 minute;

[0070] 6. The pressed discs and rings were placed in a microwave sintering furnace for heat treatment at 1150°C for 4 hours. The spinel NiZnCo ferrite material, i.e., praseodymium-doped nickel-zinc-cobalt ferrite, was obtained. The SEM morphology is shown in Figure 2 The SEM morphology shows that the prepared praseodymium-doped nickel-zinc-cobalt ferrite is polyhedral in shape. In addition, the particle size is observed to be smaller than that of comparative example 1, which may be due to the change in crystal structure caused by praseodymium doping. Figure 7 The table shows the concentration of each element in the ferrite. In Example 1, a trace amount of Pr was detected, with an atomic concentration of 0.003, indicating that the praseodymium element has entered the lattice of the nickel-zinc-cobalt ferrite, which is in line with expectations.

[0071] 7. Measure the sintered density, initial magnetic permeability, cutoff frequency, dielectric loss and DC resistivity of the material.

[0072] Example 2

[0073] 1. According to Ni 0.5 Zn 0.3 Co 0.15 Pr 0.05 Fe 1.95 The O4 component was prepared into a 1 L solution with a concentration of 0.3 mol / L. 13.5603 g of Ni(NO3)2·6H2O, 7.4970 g of Zn(NO3)2·6H2O, 3.6640 g of Co(NO3)2·6H2O, 66.4574 g of Fe(NO3)3·9H2O, and 1.8256 g of Pr(NO3)3·6H2O were weighed, totaling 93.0043 g of powder. All of the above powders were added to a beaker, and deionized water was added to mix and stir for 30 minutes until all nitrates were dissolved. Citric acid was then added at a molar ratio of 3:1 to nitrates.

[0074] 2. Stir the prepared solution with a constant temperature magnetic stirrer at 80°C for 4 h while gradually adding ammonia water to maintain the pH at 7 to obtain a wet gel precursor.

[0075] 3. Place the obtained wet gel precursor in an oven and dry it at 80°C to obtain a dry gel precursor;

[0076] 4. Heating the xerogel precursor to cause self-propagating combustion into nano-sized powders, followed by the addition of 10 wt% polyvinyl alcohol for granulation;

[0077] 5. Add the granulated powder into the mold and press into discs (Ø10 mm × h2 mm, 10 MPa) and rings (Ø18 mm × h2 mm, 20 MPa) on a manual hydraulic press, maintaining the pressure for 1 minute;

[0078] 6. The pressed discs and rings were placed in a microwave sintering furnace for heat treatment at 1150°C for 4 hours. The spinel NiZnCo ferrite material, i.e., praseodymium-doped nickel-zinc-cobalt ferrite, was obtained. The SEM morphology is shown in Figure 3 The SEM morphology shows that the prepared praseodymium-doped nickel-zinc-cobalt ferrite is polyhedral in shape. In addition, the particle size is observed to be smaller than that in Example 1, which further indicates that praseodymium doping may cause changes in the crystal structure. Figure 8 The table shows the concentration of each element in the ferrite. In Example 2, a trace amount of Pr was detected, with an atomic concentration of 0.008, indicating that the praseodymium element has entered the lattice of the nickel-zinc-cobalt ferrite, which is in line with expectations.

[0079] 7. Measure the sintered density, initial magnetic permeability, cutoff frequency, dielectric loss and DC resistivity of the material.

[0080] Example 3

[0081] 1. According to Ni 0.55 Zn 0.3 Co 0.15 Pr 0.075 Fe 1.925 The O4 component was prepared into a 1 L solution with a concentration of 0.3 mol / L. 13.4419 g of Ni(NO3)2·6H2O, 7.4251 g of Zn(NO3)2·6H2O, 3.6319 g of Co(NO3)2·6H2O, 65.0309 g of Fe(NO3)3·9H2O, and 2.7144 g of Pr(NO3)3·6H2O were weighed, totaling 92.2442 g of powder. All of the above powders were added to a beaker, and deionized water was added to mix and stir for 30 minutes until all nitrates were dissolved. Citric acid was then added at a molar ratio of 3:1 to nitrates.

[0082] 2. Stir the prepared solution with a constant temperature magnetic stirrer at 80°C for 4 h while gradually adding ammonia water to maintain the pH at 7 to obtain a wet gel precursor.

[0083] 3. Place the obtained wet gel precursor in an oven and dry it at 80°C to obtain a dry gel precursor;

[0084] 4. Heating the xerogel precursor to cause self-propagating combustion into nano-sized powders, followed by the addition of 10 wt% polyvinyl alcohol for granulation;

[0085] 5. Add the granulated powder into the mold and press into discs (Ø10 mm × h2 mm, 10 MPa) and rings (Ø18 mm × h2 mm, 20 MPa) on a manual hydraulic press, maintaining the pressure for 1 minute;

[0086] 6. The pressed discs and rings were placed in a microwave sintering furnace for heat treatment at 1150°C for 4 hours. The spinel NiZnCo ferrite material, i.e., praseodymium-doped nickel-zinc-cobalt ferrite, was obtained. The SEM morphology is shown in Figure 4 The SEM morphology shows that the prepared praseodymium-doped nickel-zinc-cobalt ferrite is in a polyhedral shape. In addition, compared with Example 2, the particle size of the prepared praseodymium-doped nickel-zinc-cobalt ferrite particles is observed to be smaller. This observation further supports the hypothesis that praseodymium doping causes changes in the crystal structure. Figure 9 The table shows the concentration of each element in the ferrite. In test example 3, a trace amount of Pr was detected, with an atomic concentration of 0.013, indicating that the praseodymium element has entered the lattice of the nickel-zinc-cobalt ferrite, which is in line with expectations.

[0087] 7. Measure the sintered density, initial magnetic permeability, cutoff frequency, dielectric loss and DC resistivity of the material.

[0088] Example 4

[0089] 1. According to Ni 0.55 Zn 0.3 Co 0.15 Pr 0.1 Fe 1.9 The O4 component was prepared into a 1 L solution with a concentration of 0.3 mol / L. 13.3252 g of Ni(NO3)2·6H2O, 7.3607 g of Zn(NO3)2·6H2O, 3.6004 g of Co(NO3)2·6H2O, 63.6292 g of Fe(NO3)3·9H2O, and 3.5877 g of Pr(NO3)3·6H2O were weighed, totaling 91.5032 g of powder. All of the above powders were added to a beaker, and deionized water was added to mix and stir for 30 minutes until all nitrates were dissolved. Citric acid was then added at a molar ratio of 3:1 to nitrates.

[0090] 2. Stir the prepared solution with a constant temperature magnetic stirrer at 80°C for 4 h while gradually adding ammonia water to maintain the pH at 7 to obtain a wet gel precursor.

[0091] 3. Place the obtained wet gel precursor in an oven and dry it at 80°C to obtain a dry gel precursor;

[0092] 4. Heating the xerogel precursor to cause self-propagating combustion into nano-sized powders, followed by the addition of 10 wt% polyvinyl alcohol for granulation;

[0093] 5. Add the granulated powder into the mold and press into discs (Ø10 mm × h2 mm, 10 MPa) and rings (Ø18 mm × h2 mm, 20 MPa) on a manual hydraulic press, maintaining the pressure for 1 minute;

[0094] 6. The pressed discs and rings were placed in a microwave sintering furnace for heat treatment at 1150°C for 4 hours. The spinel NiZnCo ferrite material, i.e., praseodymium-doped nickel-zinc-cobalt ferrite, was obtained. The SEM morphology is shown in Figure 5 The SEM morphology shows that the prepared praseodymium-doped nickel-zinc-cobalt ferrite is in a polyhedral shape. In addition, compared with Example 3, the particle size of the praseodymium-doped nickel-zinc-cobalt ferrite particles prepared in Example 4 is observed to be smaller. This observation further supports the hypothesis that praseodymium doping leads to changes in the crystal structure. Figure 6 It can be seen that the table shows the concentration of each element contained in the ferrite. In Comparative Example 1, nickel, zinc, cobalt, iron, and oxygen elements were detected, which verified the formation of nickel-zinc-cobalt ferrite. Figure 10 The table shows the concentration of each element in the ferrite. In test example 4, a trace amount of Pr was detected, with an atomic concentration of 0.016, indicating that the praseodymium element has entered the lattice of the nickel-zinc-cobalt ferrite, which is in line with expectations.

[0095] 7. Measure the sintered density, initial magnetic permeability, cutoff frequency, dielectric loss and DC resistivity of the material.

[0096] Comparative Example 1

[0097] 1. According to Ni 0.55 Zn 0.3 Co 0.15The Fe2O4 component was prepared into a 1 L solution with a concentration of 0.3 mol / L. 13.8045 g of Ni(NO3)2·6H2O, 7.6254 g of Zn(NO3)2·6H2O, 3.7299 g of Co(NO3)2·6H2O, and 69.3874 g of Fe(NO3)3·9H2O were weighed, totaling 94.5472 g of powder. All of the above powders were added to a beaker, and deionized water was added to mix and stir for 30 minutes until all nitrates were dissolved. Citric acid was then added at a molar ratio of 3:1 to nitrates.

[0098] 2. Stir the prepared solution with a constant temperature magnetic stirrer at 80°C for 4 h while gradually adding ammonia water to maintain the pH at 7 to obtain a wet gel precursor.

[0099] 3. Place the obtained wet gel precursor in an oven and dry it at 80°C to obtain a dry gel precursor;

[0100] 4. Heating the xerogel precursor to cause self-propagating combustion into nano-sized powders, followed by the addition of 10 wt% polyvinyl alcohol for granulation;

[0101] 5. Add the granulated powder into the mold and press into discs (Ø10 mm × h2 mm, 10 MPa) and rings (Ø18 mm × h2 mm, 20 MPa) on a manual hydraulic press, maintaining the pressure for 1 minute;

[0102] 6. The pressed discs and rings were placed in a microwave sintering furnace for heat treatment at 1150°C for 4 hours. The spinel NiZnCo ferrite material, i.e., praseodymium-doped nickel-zinc-cobalt ferrite, was obtained. The SEM morphology is shown in Figure 1 The SEM morphology shows that the prepared nickel-zinc-cobalt ferrite is polyhedral in shape, which is consistent with the theory of spinel structure. In the spinel structure, metal ions can be in a hexahedral or octahedral coordination environment, which may lead to the polyhedral shape of the particles.

[0103] 7. Measure the sintered density, initial magnetic permeability, dielectric loss and DC resistivity of the material.

[0104] The detection method of the present invention is as follows:

[0105] 1. The diameter and thickness of the sintered samples were measured using a micrometer caliper, and the mass was weighed using a high-precision electronic balance (FA2104J) with an accuracy of 0.1 mg.

[0106] 2. The initial magnetic permeability of the sintered samples was measured by Agilent HP4291B.

[0107] 3. The coercivity of the sintered samples was obtained by measuring the hysteresis loop using a Lake Shore 8604 vibrating sample magnetometer in the magnetic field range of -6000 to +6000 Oe at room temperature.

[0108] 4. The DC resistivity of the sintered samples was measured using a GWM-200 high-temperature dielectric measurement device in the temperature range of 30 to 300°C.

[0109] 5. The dielectric loss of the sintered samples was measured using a WK 6500P LCR meter in the frequency range of 100 Hz to 1 MHz.

[0110] The sintering density d and initial magnetic permeability μ of the specific embodiments 1-4 of the present invention and the comparative example 1 i (10 MHz), coercivity Hc, cutoff frequency f r The test results of dielectric loss tanδ and DC resistivity ρ are shown in Table 1.

[0111] Table 1

[0112]

[0113] It can be seen from Table 1 that the sintering density of the examples is lower than that of the comparative examples. This may be because Pr 3+ The radius of the ion is larger than that of Fe 3+ The ions are large. After the introduction of Pr element, the initial magnetic permeability of ferrite decreases. The initial magnetic permeability of Example 4 at 10MHz reaches the minimum value of 5.94332. The coercive force of the embodiment remains basically unchanged compared with the comparative example. 3+ As the doping amount increases, the cutoff frequency f r The improvement is great, which may be due to the reduction of the initial permeability. The cut-off frequency f of Example 4 is r The dielectric loss of Example 1 at 100 Hz reaches a minimum of 0.41417, and the DC resistivity ρ at 30°C reaches a maximum of 4.756×10 6 In general, the praseodymium-doped nickel-zinc-cobalt ferrite of the present invention has a high cutoff frequency, a relatively high DC resistivity, and a low dielectric loss, and can provide a key material for high-frequency inductors and capacitors.

[0114] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A praseodymium-doped nickel-zinc-cobalt ferrite, characterized in that: The molecular formula of praseodymium-doped nickel-zinc-cobalt ferrite is: Ni 0.55 Zn 0.3 Co 0.15 Pr x Fe 2-x O4, where 0.025≤x≤0.

1.

2. A method for preparing praseodymium-doped nickel-zinc-cobalt ferrite, for preparing the praseodymium-doped nickel-zinc-cobalt ferrite according to claim 1, characterized in that: The steps include: a. Prepare a wet gel precursor: Mix nickel salt, zinc salt, cobalt salt, iron salt, praseodymium salt and deionized water, add citric acid after dissolving, and stir at 70-90°C for 2-4 hours while controlling the pH value of the reaction system to 6.5-7.5 to obtain a wet gel precursor; b. Preparing a dry gel precursor: drying the wet gel precursor obtained in step a to obtain a dry gel precursor; c. Self-propagating combustion reaction: heating the dry gel precursor to make it self-propagating combustion into nano-scale powder, and then adding polyvinyl alcohol for granulation; d. Blank making: the granulated powder is pressed into blanks; e. Microwave sintering: Place the blank in a microwave sintering furnace and sinter it to obtain praseodymium-doped nickel-zinc-cobalt ferrite.

3. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, wherein: In step a, the nickel salt is nickel nitrate, the zinc salt is zinc nitrate, the cobalt salt is cobalt nitrate, the iron salt is iron nitrate, and the praseodymium salt is praseodymium nitrate.

4. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, wherein: In step a, the amount of citric acid added is 2 to 4 times the sum of the amounts of nickel salt, zinc salt, cobalt salt, iron salt and praseodymium salt.

5. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, wherein: In step a, the reaction temperature is 80° C., the reaction is stirred for 4 h, and the pH value of the reaction system is controlled to be 7.

6. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, wherein: In step c, the amount of polyvinyl alcohol added is 6 to 10 wt% of the weight of the nano-powder.

7. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, characterized in that: In step d, the pressing pressure is 5 to 25 MPa, and the pressing time is 0.5 to 2 min.

8. The method for preparing praseodymium-doped nickel-zinc-cobalt ferrite according to claim 2, wherein: In step e, the blank is sintered at a temperature of 1000-1200° C. for a time of 1-4 hours.

Images