A high-permeability cobalt-bismuth-nickel micro / nano soft magnetic material and its preparation method

Abstract

This invention discloses a high-permeability cobalt-bismuth-nickel micro / nano soft magnetic material and its preparation method. The micro / nano soft magnetic material exhibits high permeability at ultra-high frequencies. The material is micrometer-scale and chain-like. In this invention, different amounts of cobalt, nickel, and bismuth salts, along with an alkali, are uniformly mixed in a reducing solution environment. A certain amount of complexing agent and surfactant are then added to orderly complex the ions through interaction, modifying the surface of the CoBiNi micro / nano particles. The liquid mixture is gradually heated to 150°C. o C-250 o C, hydrothermal reaction for 8-24 hours. This invention has the advantages of simple operation and low cost. The prepared micro-nano soft magnetic materials maintain high permeability in the ultra-high frequency and super-high frequency bands (1GHz-18GHz). After measurement by a vector network analyzer (VNA), the prepared CoBiNi micro-nano particles still maintain a permeability of over 3.00 at ultra-high frequencies of 16.04GHz-16.86GHz, and can reach a maximum of 4.27, which is dedicated to meeting the high permeability requirements of 5G communication materials at specific frequencies.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-nano soft magnetic materials, and more particularly to a cobalt-bismuth-nickel micro-nano particle with high magnetic permeability under an ultra-high frequency band and a preparation method thereof. BACKGROUND

[0002] In today's information age, the explosive growth of mobile data traffic, the rapid growth of connected devices, cloud services, hyper-realistic media for converged services, and big data analysis driven by five trends, 5G communication has emerged. In order to meet the strict bandwidth requirements of 5G communication, at present, a large number of dense base stations are deployed in the millimeter wave range. This brings the problem of high energy consumption of 5G. The high energy consumption of communication base stations cannot be solved in time, and the high energy consumption will be more serious in the future 6G communication era. Therefore, the development of antenna substrate materials with high transmission performance and low energy consumption is of great significance for the transmission of 5G signals in a larger range.

[0003] In order to realize low-power transmission of signals, the antenna substrate material needs to meet the four basic characteristics of low dielectric constant, low dielectric loss, high magnetic permeability, and low magnetic loss. The magnetic permeability of the material is the most core index affecting the energy consumption and wireless transmission of the base station. At present, the high magnetic permeability magnetic powder produced on a large scale does not meet the requirements of 5G communication applications. Therefore, finding a simple, process-controllable, low-cost, and reproducible method to prepare high magnetic permeability magnetic powder is still a difficult problem to be solved in the process of 5G communication practical application such as unmanned aerial vehicle control and automatic driving, and further exploration and research are needed. SUMMARY

[0004] The present application provides a simple, process-controllable, and low-cost method for preparing high magnetic permeability cobalt-bismuth-nickel (CoBiNi) micro-nano soft magnetic material, which meets the demand of 5G communication materials.

[0005] The present application achieves the above-mentioned purposes by the following technical solutions:

[0006] A cobalt-bismuth-nickel micro-nano particle with high magnetic permeability under an ultra-high frequency band and a preparation method thereof. In a reducing solution environment, different contents of cobalt salt, nickel salt, and bismuth salt are mixed with alkali and uniformly mixed. Under the interaction of complexing agent and surfactant, the ions are orderly complexed, and the surface of the CoBiNi micro-nano particle is modified. Then, a hydrothermal reduction reaction is performed, which specifically includes the following steps:

[0007] 1) In a reducing solution, add cobalt salt, nickel salt, bismuth salt, and alkali, and mix and dissolve; add a certain amount of complexing agent and surfactant to the obtained mixed solution, and perform ultrasonic mixing;

[0008] 2) The liquid phase after ultrasonic mixing is heated to 150 o C-250 o C The hydrothermal reduction reaction is 8h-24h;

[0009] 3) After the reaction, the solid-liquid mixture is separated;

[0010] 4) The reaction product obtained in step 3) is washed multiple times using alcohol solution magnetic decantation to remove the solvent and impurities attached to the surface of the reaction product;

[0011] 5) The reaction product obtained in step 4) is vacuum dried at 40℃-100℃ for 60 min-600 min.

[0012] Preferably, the cobalt salt is any one of cobalt acetate, cobalt nitrate, and cobalt sulfate.

[0013] Preferably, the nickel salt is any one of nickel acetate, nickel nitrate, and nickel sulfate.

[0014] Preferably, the bismuth salt is any one of bismuth sulfate and bismuth nitrate.

[0015] Preferably, the molar number of cobalt salt accounts for 20.00% of the total molar number of cobalt salt, nickel salt, and bismuth salt, the molar number of nickel salt accounts for 70.00%-79.00% of the total molar number of cobalt salt, nickel salt, and bismuth salt, and the molar number of bismuth salt accounts for 1.00%-10.00% of the total molar number of cobalt salt, nickel salt, and bismuth salt.

[0016] Preferably, the base is any one of sodium hydroxide and potassium hydroxide.

[0017] Preferably, in step 1), the molar concentration of the base in the liquid phase after ultrasonic mixing is 0.75molL -1 -1.00molL -1 .

[0018] Preferably, the complexing agent is any one of triethylamine and diethylene; the complexing agent accounts for 3.75%-5.00% of the total volume of the complexing agent and the reducing solution.

[0019] Preferably, the surfactant is cetyltrimethylammonium bromide. The molar concentration of the surfactant in the liquid phase after ultrasonic mixing is 0.075molL -1 -0.100molL -1 .

[0020] Preferably, the reducing solution is any one of glycerol and ethylene glycol.

[0021] Preferably, the hydrothermal reduction reaction uses a polytetrafluoroethylene inner reaction kettle, and the reaction kettle has an inner lining, and the material of the inner lining includes but is not limited to one of a copolymer of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene, polytetrafluoroethylene and fluorinated ethylene propylene copolymer.

[0022] Preferably, the alcohol solution is anhydrous ethanol.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] 1. The present application uses a hydrothermal reduction method to prepare Co 20 Bi5Ni 75 The micro-nano soft magnetic material has relatively high magnetic permeability in a specific frequency band interval of an ultra-high frequency, that is, the prepared Co 20 Bi5Ni 75 The micro-nano soft magnetic material keeps the magnetic permeability above 3.00 in the frequency band interval of 16.04GHz-16.86GHz, and the highest can reach 4.27, which promotes the long-distance transmission of 5G communication signals.

[0025] 2. The present application has simple preparation process and low cost, and has been in pilot test in enterprises, and has the ability of large-scale production.

[0026] The series of CoBiNi micro-nano soft magnetic materials prepared by the present application are chain-shaped, the bismuth ions in the crystal structure can inhibit the movement of carriers in the structure, which helps to reduce eddy current loss, control magnetic loss, reduce energy consumption of the whole society, and help energy saving and emission reduction. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the scanning electron microscope image of the corresponding Co 20 Bi1Ni 79 micro-nano soft magnetic material in example 1.

[0028] Figure 2 is the scanning electron microscope image of the corresponding Co 20 Bi2Ni 78 micro-nano soft magnetic material in example 2.

[0029] Figure 3 is the scanning electron microscope image of the corresponding Co 20 Bi5Ni 75 micro-nano soft magnetic material in example 3.

[0030] Figure 4 is the scanning electron microscope image of the corresponding Co 20 Bi 10 Ni 70 micro-nano soft magnetic material in example 4.

[0031] Figure 5is the corresponding Co of Example 5 20 Bi 10 Ni 70 Scanning electron micrograph of the micro-nano soft magnetic material.

[0032] Figure 6 is the corresponding Co of Comparative Example 1 20 Bi5Ni 75 Scanning electron micrograph of the micro-nano soft magnetic material.

[0033] Figure 7 is the corresponding Co of Comparative Example 2 20 Bi 10 Ni 70 Scanning electron micrograph of the micro-nano soft magnetic material.

[0034] Figure 8 is the corresponding Co of Comparative Example 3 20 Bi 10 Ni 70 Scanning electron micrograph of the micro-nano soft magnetic material.

[0035] Figure 9 is the corresponding Co of Comparative Example 4 20 Ni 80 Scanning electron micrograph of the micro-nano soft magnetic material.

[0036] Figure 10 Scanning electron micrograph of the CoFe2O4 micro-nano soft magnetic powder corresponding to Comparative Example 5.

[0037] Figure 11 Scanning electron micrograph of the FeSiCr micro-nano soft magnetic powder corresponding to Comparative Example 6.

[0038] Figure 12 is the corresponding Co of Example 1 20 Bi1Ni 79 Permeability curve (a) and magnetic loss curve (b) of the micro-nano soft magnetic material.

[0039] Figure 13 is the corresponding Co of Example 2 20 Bi2Ni 78 Permeability curve (a) and magnetic loss curve (b) of the micro-nano soft magnetic material.

[0040] Figure 14 is the corresponding Co of Example 3 20 Bi5Ni 75 Permeability curve (a) and magnetic loss curve (b) of the micro-nano soft magnetic material.

[0041] Figure 15 is the corresponding Co of Example 4 20 Bi 10 Ni70 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0042] Figure 16 is the corresponding CoFe2O4 micro-nano soft magnetic material in Example 5 20 Bi5Ni 75 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0043] Figure 17 is the corresponding CoFe2O4 micro-nano soft magnetic material in Comparative Example 1 20 Bi5Ni 75 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0044] Figure 18 is the corresponding CoFe2O4 micro-nano soft magnetic material in Comparative Example 2 20 Bi 10 Ni 70 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0045] Figure 19 is the corresponding CoFe2O4 micro-nano soft magnetic material in Comparative Example 3 20 Bi 10 Ni 70 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0046] Figure 20 is the corresponding CoFe2O4 micro-nano soft magnetic material in Comparative Example 4 20 Ni 80 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material.

[0047] Figure 21 is the permeability curve (a) and the magnetic loss curve (b) of the corresponding CoFe2O4 micro-nano soft magnetic material in Comparative Example 5

[0048] Figure 22 is the permeability curve (a) and the magnetic loss curve (b) of the corresponding FeSiCr micro-nano soft magnetic material in Comparative Example 6 DETAILED DESCRIPTION

[0049] The present application relates to a kind of cobalt bismuth nickel (CoBiNi) micro-nanoparticles with high magnetic permeability under ultra-high frequency band and its preparation method, and is committed to meet the demand of high magnetic permeability of 5G communication materials under specific frequency.The present application greatly improves the preparation efficiency of high-performance soft magnetic material by hydrothermal reaction and the interaction of surfactant and complexing agent, ordered complexation and reduction of cobalt ions, nickel ions and bismuth ions in reducing solution.The bismuth itself has higher resistivity, and bismuth ions can hinder the movement of carriers to improve the resistivity, thereby improving the magnetic permeability;The present application uses hydrothermal reduction method to prepare CoBiNi micro-nanometer soft magnetic material with different bismuth ion content, and research shows that the magnetic permeability of CoBiNi micro-nanometer soft magnetic material can be adjusted by adjusting the content of bismuth ions.The CoBiNi micro-nanometer soft magnetic material prepared by the present application still maintains high magnetic permeability at higher frequency (1-18GHz), and the prepared CoBiNi micro-nanometer soft magnetic material still maintains magnetic permeability of 3.00 or more at ultra-high frequency of 16.04GHz-16.86GHz, and the highest can reach 4.27, and its dielectric constant is also at a lower value, and is committed to meet the demand of high magnetic permeability of 5G communication materials in specific frequency range.A series of tests such as scanning electron microscopy and magnetic performance determination show that the prepared micro-nanometer soft magnetic material has higher magnetic permeability at ultra-high frequency.The present application can realize large-scale batch production of communication materials in industry through simple preparation process, and can help to solve the shortcomings of high energy consumption and short communication signal transmission distance of current communication materials, so the method is a new type of technology with commercial application potential.

[0050] The principle of the present application is that saturation magnetization (Ms) is an inherent parameter of a material, which is determined by the number of unpaired electrons outside the atomic nucleus of the material. The higher the saturation magnetization of the material, the higher the magnetic permeability of the material. The value of saturation magnetization Ms also varies with materials. Combining different materials together can obtain a multi-phase material with higher Ms than the constituent materials. For example, Fe-Co, Fe-Ni, and Fe-Si-Al composite materials have much higher Ms values than their components Fe, Co, Ni, Si, and Al. At the same time, the resistivity of the material has a great influence on the magnetic permeability at high frequency. Increasing the resistivity of the material is beneficial to reducing eddy current loss and thus reducing magnetic loss. Among them, bismuth ions can inhibit the movement of carriers between ions, thereby causing the resistivity to increase.

[0051] The micro-nanometer soft magnetic material prepared in the embodiment must have high magnetic permeability. The magnetic permeability of the 5G communication materials currently used in the market cannot meet the performance indicators of the micro-nanometer soft magnetic material in the embodiment.

[0052] Example 1

[0053] (1) In the presence of 38.00 mL of reducing solvent glycerol, 0.20 mmol of cobalt acetate, 0.79 mmol of nickel acetate, 0.01 mmol of bismuth nitrate and 30.00 mmol of potassium hydroxide are mixed and dissolved.

[0054] (2) 2.00 mL of diethylene triamine and 0.40 mmol of cetyl trimethyl ammonium bromide are added to the dissolved mixed solution, and ultrasonic mixing is performed.

[0055] (3) The above liquid mixture is transferred to a polytetrafluoroethylene lined reaction kettle, sealed and heated in an oven, the reaction temperature is 150 o C, and the reaction time is 24 h.

[0056] (4) After the above reaction is completed, the reaction kettle is cooled to room temperature, and the obtained solid-liquid mixture is separated by magnetic attraction.

[0057] (5) The obtained reaction product is washed 5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product are removed.

[0058] (6) Drying in a vacuum oven for 60 min at 100°C.

[0059] (7) Figure 1 Co 20 Bi1Ni 79 micro-nano soft magnetic material obtained is a chain structure; Figure 12 Co 20 Bi1Ni 79 micro-nano soft magnetic material obtained is a chain structure;

[0060] Example 2

[0061] (1) In the presence of 38.50 mL of reducing solvent glycerol, 0.20 mmol of cobalt acetate, 0.79 mmol of nickel acetate, 0.01 mmol of bismuth nitrate and 30.00 mmol of potassium hydroxide are mixed and dissolved,

[0062] (2) Add 1.50 mL of triethylamine and 0.35 mmol of cetyltrimethylammonium bromide to the dissolved mixed solution, and perform ultrasonic mixing.

[0063] (3) Transfer the above liquid mixture into a polytetrafluoroethylene inner reaction kettle, seal it, and then place it into an oven for heating, with a reaction temperature of 250 o C and a reaction time of 8 h.

[0064] (4) After the reaction is completed, cool the reaction kettle to room temperature, and separate the obtained solid-liquid mixture by magnetic attraction.

[0065] (5) Wash the obtained reaction product by magnetic decantation with anhydrous ethanol for 5 times, so as to remove the solvent and impurities attached to the surface of the reaction product.

[0066] (6) Dry in a vacuum oven for 600 min, with an oven temperature of 40°C.

[0067] (7) Figure 2 is the obtained Co 20 Bi2Ni 78 micro-nano soft magnetic material, and the morphology thereof is a chain structure; Figure 13 is the obtained Co 20 Bi2Ni 78 micro-nano soft magnetic material, and the permeability curve (a) and the magnetic loss curve (b) thereof are shown in the figure. It is measured that the permeability thereof remains above 3.00 in the frequency range of 17.00 GHz-18.00 GHz, and the highest value can reach 3.20, while the magnetic loss fluctuates around 0 in the frequency range of 1.00 GHz-16.00 GHz, and the magnetic loss value is small. This shows that the permeability of the magnetic powder at a high frequency meets the requirements, and the magnetic loss is small, which meets the application requirements.

[0068] Example 3

[0069] (1) In the presence of 38.00 mL of reducing solvent ethylene glycol, 0.20 mmol of cobalt nitrate, 0.75 mmol of nickel nitrate, 0.05 mmol of bismuth sulfate and 31.25 mmol of sodium hydroxide are fully mixed and dissolved,

[0070] (2) Add 2.00 mL of diethylene triamine and 0.35 mmol of cetyltrimethylammonium bromide to the dissolved mixed solution, and perform ultrasonic mixing.

[0071] (3) Transfer the above liquid mixture into a polytetrafluoroethylene inner reaction kettle, seal it, and then place it into an oven for heating, with a reaction temperature of 220 o C and a reaction time of 20 h.

[0072] (4) After the reaction, the reactor is cooled to room temperature, and the obtained solid-liquid mixture is separated by magnetic attraction.

[0073] (5) The obtained reaction product is washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product are removed.

[0074] (6) Drying in a vacuum oven for 360 min at 60°C.

[0075] (7) Figure 3 is the obtained Co 20 Bi5Ni 75 The scanning electron microscope image of the micro-nano soft magnetic material has a chain structure. Figure 14 is the obtained Co 20 Bi5Ni 75 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material show that the permeability remains above 3.00 in the frequency range of 16.04 GHz-16.86 GHz, and the highest value is 4.27. The magnetic loss fluctuates around 0.20 in the frequency range of 1 GHz-17 GHz. The magnetic loss value is small. This shows that the magnetic powder has a high permeability at a specific frequency and a small magnetic loss, which meets the application requirements.

[0076] Example 4

[0077] (1) In the presence of 38.50 mL of reducing solvent ethylene glycol, 0.20 mmol of cobalt sulfate, 0.70 mmol of nickel acetate, 0.10 mmol of bismuth nitrate, and 31.25 mmol of sodium hydroxide are thoroughly mixed and dissolved

[0078] (2) Add 1.50 mL of diethylene triamine and 0.30 mmol of cetyl trimethyl ammonium bromide to the dissolved mixed solution, and mix by ultrasonic.

[0079] (3) The above liquid mixture is transferred to a polytetrafluoroethylene inner reactor, sealed, and then placed in an oven for heating. The reaction temperature is 220 o C, and the reaction time is 20 h.

[0080] (4) After the reaction, the reactor is cooled to room temperature, and the obtained solid-liquid mixture is separated by magnetic attraction.

[0081] (5) The obtained reaction product is washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product are removed.

[0082] (6) Drying in a vacuum oven for 360 min at 60°C.

[0083] (7) Figure 4 Co 20 Bi 10 Ni 70 SEM image of the micro-nano soft magnetic material, which has a chain structure; Figure 15 Co 20 Bi 10 Ni 70 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material, the measured permeability reaches a maximum value of 1.44 at 2.04 GHz, and the permeability basically remains above 1.10 in the frequency range of 1.00-6.00 GHz, and the permeability is 1.20 at about 17.00 GHz; the magnetic loss fluctuates around 0.40 in the range of 1.00-15.00 GHz, and the magnetic loss fluctuates slightly in the range of 15.00-18.00 GHz, and the maximum magnetic loss value can reach 0.70. This shows that the permeability of the magnetic powder at high frequency meets the requirements, and basically meets the application requirements.

[0084] Example 5

[0085] (1) In the presence of 38.00 mL of reducing solvent ethylene glycol, 0.20 mmol of cobalt acetate, 0.70 mmol of nickel acetate, 0.10 mmol of bismuth nitrate, and 31.25 mmol of potassium hydroxide were thoroughly mixed and dissolved

[0086] (2) 2.00 mL of diethylene triamine and 0.30 mmol of hexadecyl trimethyl ammonium bromide were added to the dissolved mixed solution, and ultrasonic mixing was performed.

[0087] (3) The above liquid mixture was transferred to a polytetrafluoroethylene inner reaction kettle, sealed and placed in an oven for heating, the reaction temperature was 220 o C, and the reaction time was 15 h.

[0088] (4) After the above reaction was completed, the reaction kettle was cooled to room temperature, and the obtained solid-liquid mixture was separated by magnetic attraction.

[0089] (5) The obtained reaction product was washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product were removed.

[0090] (6) Dried in a vacuum oven for 360 min, and the oven temperature was 60°C.

[0091] (7) Figure 5 Co 20 Bi 10 Ni 70 SEM image of the micro-nano soft magnetic material, which has a chain structure; Figure 16Co 20 Bi 10 Ni 70 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material are shown in the figure. The permeability reaches the maximum value of 1.30 at 2.04 GHz, and the permeability basically remains above 1.10 in the frequency range of 1.00-5.00 GHz and 16.00-17.00 GHz. The magnetic loss fluctuates around 0.10 in the frequency range of 1-15 GHz, and the fluctuation range of the magnetic loss is large in the frequency range of 15.00-18.00 GHz, reaching about 0.5. This shows that the permeability of the magnetic powder at high frequency and specific frequency basically meets the requirements, and basically meets the application requirements.

[0092] Comparative Example 1

[0093] (1) 0.20 mmol of cobalt acetate, 0.75 mmol of nickel acetate, 0.05 mmol of bismuth nitrate, and 31.25 mmol of sodium hydroxide were fully mixed and dissolved in the presence of 40 mL of a reducing solvent ethylene glycol

[0094] (2) 0.40 mmol of cetyltrimethylammonium bromide was added to the dissolved mixed solution, and ultrasonic mixing was performed.

[0095] (3) The above liquid mixture was transferred to a polytetrafluoroethylene inner reaction kettle, sealed, and then transferred to an oven for heating. The reaction temperature was 220 o C, and the reaction time was 20 h.

[0096] (4) After the above reaction was completed, the reaction kettle was cooled to room temperature, and the obtained solid-liquid mixture was separated by magnetic attraction.

[0097] (5) The obtained reaction product was washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product were removed.

[0098] (6) Dried in a vacuum oven for 360 min at an oven temperature of 60°C.

[0099] (7) Figure 6 Co 20 Bi5Ni 75 The scanning electron microscope image of the micro-nano soft magnetic material shows a spherical structure. Figure 17 Co 20 Bi5Ni 70The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material, the permeability reaches the maximum value of 1.16 at 1.00 GHz, and the permeability basically remains around 1.00 in the frequency range of 1.00-18.00 GHz, and the minimum permeability is 0.90; the magnetic loss fluctuates around 0.10 in the frequency range of 1.00-9.50 GHz, and the magnetic loss fluctuates around 0 in the frequency range of 9.50-18.00 GHz. This shows that the permeability of the magnetic powder at high frequency is low, which does not meet the application requirements.

[0100] Comparative Example 2

[0101] (1) In the presence of 40.00 mL of reducing solvent ethylene glycol, 0.20 mmol of cobalt acetate, 0.70 mmol of nickel acetate, 0.10 mmol of bismuth nitrate and 31.25 mmol of sodium hydroxide were mixed and dissolved

[0102] (2) 0.40 mmol of cetyltrimethylammonium bromide was added to the dissolved mixed solution, and ultrasonic mixing was performed.

[0103] (3) The above liquid mixture was transferred to a polytetrafluoroethylene inner reaction kettle, sealed and transferred to an oven for heating, the reaction temperature was 220 o C, and the reaction time was 15 h.

[0104] (4) After the above reaction was completed, the reaction kettle was cooled to room temperature, and the obtained solid-liquid mixture was separated by magnetic attraction.

[0105] (5) The obtained reaction product was washed 4-5 times by magnetic decantation method with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product were removed.

[0106] (6) Dried in a vacuum oven for 360 min, and the oven temperature was 60°C.

[0107] (7) Figure 7 Co 20 Bi 10 Ni 70 The scanning electron microscope image of the micro-nano soft magnetic material, the morphology is spherical structure; Figure 18 Co 20 Bi 10 Ni 70The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material are shown in the figure. The permeability reaches the maximum value of 1.07 at 2.04 GHz, and the permeability basically remains above 0.95 in the frequency range of 5.12-9.96 GHz, and the permeability basically remains at 0.90 in the frequency range of 10.00-18.00 GHz. The magnetic loss fluctuates around 0.10 in the frequency range of 1.00-8.50 GHz, and the magnetic loss fluctuates around 0 in the frequency range of 9.00-18.00 GHz. This shows that the permeability of the magnetic powder at high frequency is low, which does not meet the application requirements.

[0108] Comparative Example 3

[0109] (1) 0.20 mmol of cobalt acetate, 0.70 mmol of nickel acetate, 0.10 mmol of bismuth nitrate and 31.25 mmol of sodium hydroxide were mixed and dissolved in the presence of 39.00 mL of a reducing solvent ethylene glycol.

[0110] (2) 1.00 mL of diethylene triamine and 0.40 mmol of cetyl trimethyl ammonium bromide were added to the dissolved mixed solution, and ultrasonic mixing was performed.

[0111] (3) The above liquid mixture was transferred to a polytetrafluoroethylene inner reaction kettle, sealed and transferred to an oven for heating, and the reaction temperature was 220 o C, and the reaction time was 20 h.

[0112] (4) After the above reaction was completed, the reaction kettle was cooled to room temperature, and the obtained solid-liquid mixture was separated by magnetic attraction.

[0113] (5) The obtained reaction product was washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product were removed.

[0114] (6) Dried in a vacuum oven for 360 min, and the oven temperature was 60°C.

[0115] (7) Figure 8 Co 20 Bi5Ni 70 The scanning electron microscope image of the micro-nano soft magnetic material is shown in the figure, and the morphology is spherical structure. Figure 19 Co 20 Bi5Ni 70The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material, the permeability reaches the maximum value of 1.15 at 1.00 GHz, and the permeability basically remains 0.90 in the frequency range of 1.00 GHz-18.00 GHz; the magnetic loss fluctuates around 0.10 in the frequency range of 1.00 GHz-10.00 GHz, and the magnetic loss fluctuates slightly in the frequency range of 12.00-18.00 GHz, and the maximum magnetic loss value can reach 0.23. This shows that the permeability of the magnetic powder at high frequency is low, which does not meet the application requirements.

[0116] Comparative Example 4

[0117] (1) In the presence of 38.00 mL of reducing solvent ethylene glycol, 0.20 mmol of cobalt acetate, 0.80 mmol of nickel acetate and 31.25 mmol of sodium hydroxide were mixed and dissolved

[0118] (2) 2.00 mL of diethylene triamine was added to the dissolved mixed solution, and ultrasonic mixing was performed.

[0119] (3) The above liquid mixture was transferred to a polytetrafluoroethylene inner reaction kettle, sealed and transferred to an oven for heating, the reaction temperature was 220 o C, and the reaction time was 15 h.

[0120] (4) After the above reaction was completed, the reaction kettle was cooled to room temperature, and the obtained solid-liquid mixture was separated by magnetic attraction.

[0121] (5) The obtained reaction product was washed 4-5 times by magnetic decantation with anhydrous ethanol. The solvent and impurities attached to the surface of the reaction product were removed.

[0122] (6) Dried in a vacuum oven for 360 min, and the oven temperature was 60°C.

[0123] (7) Figure 9 Co 20 Ni 80 The scanning electron microscope image of the micro-nano soft magnetic material, and the morphology is also a chain structure; Figure 20 Co 20 Ni 80 The permeability curve (a) and the magnetic loss curve (b) of the micro-nano soft magnetic material, the permeability basically remains around 1.00 in the frequency range of 1.00 GHz-18.00 GHz, because the permeability fluctuates gently, resulting in a small magnetic loss, which fluctuates around 0.05 in the frequency range of 1 GHz-18 GHz. This shows that the permeability of the magnetic powder at high frequency is low, which does not meet the application requirements.

[0124] Comparative Example 5

[0125] (1) Weigh 0.005 mol Co (NO3)2 . 6H2O, 0.01 mol Fe (NO3)3.9H2O, 10 g polyvinyl alcohol (PEG20000);

[0126] (2) Dissolve the above weighed materials completely in 400 mL deionized water;

[0127] (3) Adjust the pH value of the solution to 7 with ammonia water, and obtain a brownish red solution;

[0128] (4) Dry on a hot plate at 80°C to obtain a brown porous gel;

[0129] (5) Then calcine at 950°C for 8 hours to obtain CoFe2O4 ferrite soft magnetic powder.

[0130] (6) Figure 10 is a scanning electron microscope image of the obtained CoFe2O4 micro-nano soft magnetic material, and the microstructure of the obtained CoFe2O4 soft magnetic material is granular; Figure 21 is the permeability curve (a) and magnetic loss curve (b) of the obtained CoFe2O4 micro-nano soft magnetic material, and the measured permeability is about 0.90 in the frequency range of 1.00 GHz-18.00 GHz, and the permeability at high frequency is low; the magnetic loss is about 0.80 in the frequency range of 1.00 GHz-18 GHz, and the magnetic loss is large. This shows that the magnetic powder has low permeability and high magnetic loss at high frequency, which does not meet the application requirements.

[0131] Comparative Example 6

[0132] Figure 11 is a scanning electron microscope image of FeSiCr micro-nano soft magnetic powder produced by Shenzhen Placone New Material Co., Ltd., which has high saturation magnetic induction intensity, low loss and other characteristics, and has potential application in wireless communication; Figure 22 is the permeability curve (a) and magnetic loss curve (b) of the FeSiCr micro-nano soft magnetic material, which shows that the permeability of the FeSiCr micro-nano soft magnetic powder slowly decreases in the frequency range of 1.00 GHz-18.00 GHz and maintains at about 1.00; the magnetic loss fluctuates around 0.05 in the frequency range of 1.00 GHz-18 GHz. This shows that the magnetic powder has low permeability at high frequency, which does not meet the application requirements.

[0133] The above experiments show that in the reducing solution, through the interaction of the surfactant and the complexing agent, the cobalt ions, nickel ions and bismuth ions are orderly complexed through the hydrothermal reaction, and the preparation efficiency of the high-performance soft magnetic material is greatly improved. Bismuth itself has a relatively high resistivity, and bismuth ions can hinder the movement of carriers to improve the resistivity, thereby improving the magnetic permeability; the CoBiNi micro-nano soft magnetic material with different bismuth ion contents is prepared by using the hydrothermal reduction method in the experiment, and research shows that the magnetic permeability of the CoBiNi micro-nano soft magnetic material can be adjusted by adjusting the bismuth ion content. The CoBiNi micro-nano soft magnetic material prepared in the application still maintains high magnetic permeability at a relatively high frequency (1.00-18.00 GHz), and through the measurement of a vector network analyzer (VNA), the CoBiNi micro-nano soft magnetic material prepared still maintains a magnetic permeability of 3.00 or more at an ultra-high frequency of 16.04 GHz-16.86 GHz, and the highest can reach 4.27, and the dielectric constant is also at a relatively low value, striving to meet the demand of the 5G communication material for high magnetic permeability in a specific frequency range.

Claims

1. A method for preparing cobalt-bismuth-nickel micro-nano soft magnetic material with high magnetic permeability in the ultra-high frequency band, characterized in that, The method comprises the following steps: 1) adding a cobalt salt, a nickel salt, a bismuth salt and a base respectively in a reducing solution, mixing and dissolving; then adding a certain amount of a complexing agent and a surfactant into the mixed solution, and ultrasonic mixing; 2) The liquid phase after ultrasonic mixing above is heated to 150 o C-250 o C Sewage thermal reduction reaction 8h-24h; 3) after the reaction, the obtained solid-liquid mixture is separated; 4) the reaction product obtained in step 3) is washed multiple times by alcohol solution magnetic decantation to remove the solvent and impurities attached to the surface of the reaction product; 5) the reaction product obtained in step 4) is vacuum dried at 40-100℃ for 60-600min; The surfactant is cetyltrimethylammonium bromide; The molar number of the cobalt salt accounts for 20.00% of the total molar number of the sum of the cobalt salt, the nickel salt and the bismuth salt, the molar number of the nickel salt accounts for 70.00%-79.00% of the total molar number of the sum of the cobalt salt, the nickel salt and the bismuth salt, and the molar number of the bismuth salt accounts for 1.00%-10.00% of the total molar number of the sum of the cobalt salt, the nickel salt and the bismuth salt; The complexing agent is selected from any one of triethylamine or diethylenetriamine; the complexing agent accounts for 3.75%-5.00% of the total volume of the complexing agent and the reducing solution; The molar concentration of the surfactant in the liquid phase after ultrasonic mixing was 0.075 mol L -1 -0.100 mol L -1 .

2. The method of claim 1, wherein, The cobalt salt is any one of cobalt acetate, cobalt nitrate or cobalt sulfate; the nickel salt is any one of nickel acetate, nickel nitrate or nickel sulfate; and the bismuth salt is any one of bismuth sulfate or bismuth nitrate.

3. The method of claim 1, wherein, The base is selected from any one of sodium hydroxide or potassium hydroxide; the molar concentration of the base in the liquid phase after ultrasonic mixing is 0.75 mol / L -1 -1.00 mol / L -1 .

4. The method of claim 1, wherein, The reducing solution is selected from any one of glycerol or ethylene glycol.

5. The cobalt-bismuth-nickel micro-nano soft magnetic material with high magnetic permeability in the ultra-high frequency band prepared by the method of any one of claims 1-4.

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