CN117070794A - Preparation method of morphology controllable magnetic nanoalloy and its application in microwave absorption - Google Patents

Abstract

A preparation method of magnetic nano alloy with controllable morphology and application in microwave absorption belong to the technical field of microwave absorption. The preparation method of the magnetic nano alloy comprises the following steps: preparing a precursor: mixing a transition metal source, a sulfur source and an organic amine solvent, heating to a preset temperature under the protection of inert gas for reaction, carrying out solid-liquid separation, and drying to obtain a precursor containing metal sulfide; the transition metal source comprises organic iron and organic transition metal, and the transition element in the organic transition metal is not iron element; the preset temperature is not higher than the boiling point of the organic amine solvent; preparing a magnetic nano alloy: under the protection of inert gas, the precursor reacts with the tri-coordination phosphorus compound to carry out desulfurization, and organic matters in the precursor are removed, so that the magnetic nano alloy is prepared in situ. The magnetic nano alloy prepared by the method has higher saturation magnetization and good electromagnetic wave absorption efficiency in a wide frequency band and a low frequency band.

Description

Preparation method of morphology controllable magnetic nanoalloy and its application in microwave absorption

Technical field

The present application relates to the technical field of microwave absorbing materials. Specifically, it relates to a preparation method of a shape-controllable magnetic nanoalloy and its application in microwave absorption.

Background technique

Microwave absorbers are mainly used for stealth coatings on aircraft, tanks or missiles and for anti-electromagnetic interference packaging layers in electronic devices. Their mechanism of action is to produce a large amount of loss to incident electromagnetic waves and reduce electromagnetic wave reflection. Inside electronic devices, complex circuits and signal generators create complex electromagnetic environments, so electromagnetic wave sensitive accessories need to be protected. Microwave absorbers can reduce electromagnetic waves in the environment, protect electromagnetic wave-sensitive parts from interference by electromagnetic waves in the environment, and ensure the normal operation of electronic devices.

Currently commercial microwave absorbers usually use ferrite powder filled with neoprene to solve electromagnetic compatibility problems when electronic devices are working and protect the normal operation of electronic devices. They are mainly used in RFID, wireless charging and other technologies, and are used in mobile phones, digital devices, etc. It is widely used in consumer products such as cameras.

However, with the development of 5G technology (Sub-6 GHz), electric frequency electronics are not easily attenuated by existing electromagnetic wave absorbers due to the longer wavelength of low-frequency electromagnetic waves. Microwave absorbers need to have higher complex magnetic permeability and Complex dielectric constant. The magnetic permeability of current ferrite materials at GHz tends to 1 as the frequency increases, and in order to achieve impedance matching, the dielectric constant is also low, and the absorption performance at low frequencies is poor. Moreover, due to limitations in the performance of existing microwave absorbing materials, the thickness of current microwave absorbers is relatively large, which is not conducive to many practical application scenarios. Therefore, the development of efficient microwave absorbers in low and wide frequency bands is an urgent problem to be solved.

Contents of the invention

Based on the above shortcomings, this application provides a preparation method of a morphology-controllable magnetic nanoalloy and its application in microwave absorption to partially or fully improve the absorption efficiency of microwave absorbing materials in related technologies for low-frequency and wide-band electromagnetic waves. low question.

This application is implemented as follows:

In a first aspect, examples of the present application provide a method for preparing a morphology-controllable magnetic nanoalloy, including:

Preparing the precursor: Mix the transition metal source, the sulfur source and the organic amine solvent, raise the temperature to the preset temperature under the protection of an inert gas for reaction, separate the solid and liquid, and dry to obtain a precursor containing metal sulfide; the transition metal source includes Organic iron and organic transition metals, the transition element in organic transition metals is not iron; the preset temperature is not higher than the boiling point of the organic amine solvent;

Preparation of magnetic nanoalloy: Under the protection of inert gas, react the precursor with a three-coordinated phosphorus compound to desulfurize and remove organic matter in the precursor to prepare the magnetic nanoalloy in situ.

In the above implementation process, after heating under the protection of inert gas, the transition metal source and sulfur source in the mixed liquid can form a precursor containing metal sulfide with a certain morphological structure under the action of the organic amine solvent. Then, the sulfur element and organic matter in the precursor are removed in the subsequent desulfurization reaction, and a magnetic nanoalloy that basically maintains the morphology and structure of the precursor can be produced in situ. The magnetic nanoalloy prepared in the example of this application has high saturation magnetization and good electromagnetic wave absorption efficiency in broadband and low frequency bands.

In conjunction with the first aspect, in an optional example of the present application, the transition element in the organic transition metal is selected from at least one of Co, Ni, Ag, Cu, Pt, Cr, Nb, Nd, Ti or Mn.

In the above implementation process, the magnetic nanoalloy formed by the transition metal and iron has high saturation magnetization and good electromagnetic wave absorption efficiency in broadband and low frequency bands.

In conjunction with the first aspect, in an optional example of this application, the organic iron is selected from at least one of iron acetylacetonate or ferrous acetylacetonate; the organic transition metal is selected from cobalt acetylacetonate, nickel acetylacetonate, silver acetylacetonate, acetylacetonate At least one of copper acetylacetonate, platinum acetylacetonate, chromium acetylacetonate, niobium acetylacetonate, neodymium acetylacetonate, titanium acetylacetonate or manganese acetylacetonate.

In connection with the first aspect, in an optional example of the present application, the sulfur source is selected from at least one of thiourea, thiosemicarbazone, sodium thiosulfate, thioacetamide or L-cysteine.

In conjunction with the first aspect, in an optional example of the present application, the organic amine solvent is selected from at least one of diethylenetriamine, triethylenetetramine, hexamethylenediamine or propylenediamine.

In the above implementation process, the organic ligand in the organic metal source is selected from acetylacetone, and can be evenly dispersed in the organic amine solvent with sulfur sources such as thiourea, sodium thiosulfate or thioacetamide. Moreover, the temperature at which acetylacetone, as an organic metal source of organic ligands, decomposes and releases metal ions in an organic amine solvent, and sulfur sources such as thiourea, sodium thiosulfate, or thioacetamide, releases sulfur element ions in an organic amine solvent. The precipitation temperature of the solvent is not much different. It can precipitate metal ions and sulfur ions almost simultaneously at a temperature lower than the boiling point of the organic amine solvent, and react to form metal sulfide. In addition, organic amine solvents such as diethylenetriamine, triethylenetetramine, hexamethylenediamine or propylenediamine can serve as a support for metal sulfides during the reaction to form precursors, and can form complexes to limit the formation of metal sulfides. Crystal morphology, obtaining a precursor with a certain morphological structure.

In conjunction with the first aspect, in an optional example of the present application, the three-coordinated phosphorus compound is selected from tri-n-octylphosphine, tricyclohexylphosphine, trialkylphosphine, tris(4-trifluorotolyl)phosphine or tritertiary phosphine At least one kind of butylphosphine.

Optionally, react the precursor with a three-coordinated phosphorus compound for desulfurization, and remove organic matter at a temperature of 270-290°C for 2-4 hours.

In the above implementation process, tri-coordinated phosphorus compounds such as tri-n-octylphosphine, tricyclohexylphosphine, trialkylphosphine, tris(4-trifluorotolyl)phosphine or tritert-butylphosphine can be used at 270-290 React with the metal sulfide in the precursor at ℃ temperature to desulfurize the metal sulfide and remove the organic matter in the precursor to obtain a magnetic nanoalloy that is basically free of sulfide and organic matter, and the morphology structure of the magnetic nanoalloy It is basically consistent with the morphology and structure of the precursor.

Combined with the first aspect, in an optional example of this application, the molar ratio of iron element to transition element in the transition metal source is 1:0.01-0.4; the molar ratio of the metal element in the transition metal source and the sulfur element in the sulfur source The ratio is 1:0.5-2.

Optional, the preset temperature is not lower than 180℃.

Optional, the preset temperature is 180-200℃.

In the above implementation process, the molar ratio of iron element to transition element in the transition metal source is 1:0.01-0.4, and an iron-based transition metal magnetic nanoalloy can be obtained. The molar ratio of the metal elements in the transition metal source and the sulfur element in the sulfur source is 1:0.5-2, and metal sulfides of different compositions can be obtained to obtain iron-based magnetic nanoalloys with different morphologies and compositions.

Moreover, when the raw materials in the mixed liquid are reacted at 180-200°C, metal ions and sulfur ions can be precipitated basically at the same time, which can react to form small crystal seeds of metal sulfides, and can also keep the organic amine solvent relatively stable. Stable coordination regulates the growth of metal sulfide crystals and adjusts the structural morphology of the precursor.

Combined with the first aspect, in an optional example of the present application, the structure of the magnetic nanoalloy is a one-dimensional structure, the sulfur source is selected from thioacetamide, and the organic amine solvent is selected from at least one of diethylenetriamine or hexamethylenediamine. kind. The magnetic nanoalloy has a two-dimensional structure, the sulfur source is selected from thiourea, and the organic amine solvent is selected from triethylenetetramine; or the sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from diethylenetriamine. The magnetic nanoalloy has a three-dimensional structure, the sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from triethylenetetramine.

In the above implementation process, the example of this application provides a method that can control the morphology and structure of magnetic nanoalloys, in which the sulfur source is selected from thioacetamide, the organic amine solvent is selected from diethylenetriamine, or the sulfur source is selected from Thioacetamide and organic amine solvents are selected from hexanediamine, which can prepare magnetic nanoalloys with one-dimensional nanofiber structures. The sulfur source is selected from thiourea and the organic amine solvent is selected from triethylenetetramine. Alternatively, the sulfur source is selected from sodium thiosulfate and the organic amine solvent is selected from diethylenetriamine. A magnetic nanoalloy with a two-dimensional nanosheet structure can be prepared. The sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from triethylenetetramine to prepare a magnetic nanoalloy with a three-dimensional block structure.

By controlling the type of reactant sulfur source and selecting different solvents, the structure and morphology of the precursor can be controlled, so that magnetic nanoalloys with specific morphologies can be produced in situ after subsequent high-temperature desulfurization. Compared with existing ferrite magnetic powders, magnetic nanoalloys with one-dimensional, two-dimensional or three-dimensional structures have more efficient low-frequency microwave absorption properties and wider microwave absorption bandwidth.

In a second aspect, examples of the present application provide a magnetic nanoalloy, the chemical composition of the magnetic nanoalloy includes at least one of iron elements and transition metal elements other than iron, and the structure of the magnetic nanoalloy includes one-dimensional and/or Two-dimensional structure.

In a third aspect, the present application provides an application of the magnetic nanoalloy provided in the second aspect in preparing a microwave absorber.

In the above implementation process, this application provides a microwave absorber prepared from magnetic nanoalloy. Since the magnetic nanoalloy has high saturation magnetization and good electromagnetic wave absorption efficiency in broadband and low frequency bands, it can improve the absorption effect of the microwave absorber.

Description of the drawings

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly introduced below.

Figure 1 is a schematic diagram of the preparation process of the nanomagnetic alloy provided as an example in this application;

Figure 2 is an SEM image of the two-dimensional FeNb nanosheets provided in Example 1 of the present application;

Figure 3 is an SEM image of the one-dimensional FeNb nanofiber provided in Example 2 of the present application;

Figure 4 is an SEM image of the three-dimensional FeNb particles provided in Example 3 of the present application;

Figure 5 is the magnetization curve provided by the test example of this application;

Figure 6 is the frequency-microwave absorption intensity curve provided by the test example of this application.

Detailed ways

The embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conditions should be carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

At present, microwave absorbers are usually made of chloroprene filled with absorbing materials such as ferrite powder. However, current microwave absorbers based on absorbing materials such as ferrite powder are not suitable for absorbing electromagnetic waves in the low frequency band, and the absorption frequency range of existing microwave absorbers is narrow.

Based on this, this application example provides a magnetic nanoalloy and a preparation method thereof to improve the problem of poor microwave absorption capabilities of microwave absorbing materials in low frequency bands and wide frequency ranges.

The preparation method of the magnetic nanoalloy provided in the examples of this application is described in detail below with reference to the accompanying drawings.

Please refer to Figure 1. The preparation method of the morphology controllable magnetic nanoalloy provided in the example of this application includes:

S1. Preparation of precursor

Mix the transition metal source, the sulfur source and the organic amine solvent, raise the temperature to a preset temperature under the protection of an inert gas for reaction, separate the solid and liquid, and dry to obtain a precursor containing metal sulfide; the transition metal source includes organic iron and organic Transition metals, the transition element in organic transition metals is not iron; the preset temperature is not higher than the boiling point of the organic amine solvent.

The transition metal source and the sulfur source are dispersed in the organic amine solvent to facilitate subsequent heating, so that the transition metal source can decompose and release metal ions, and react with the ions of sulfur element precipitated in the sulfur source to form metal sulfides. Using an organic amine as a solvent, and the reaction temperature does not exceed the boiling point of the organic amine solvent, the organic amine can be used as an organic support for the metal sulfide, and the sulfur source can be used to regulate and limit the growth of the metal sulfide seed crystal to obtain a certain The precursor of morphological structure.

In a possible embodiment, the organic amine solvent is selected from at least one of diethylenetriamine, triethylenetetramine, hexamethylenediamine or propylenediamine.

Furthermore, this application does not limit the specific type of transition metal source, and relevant personnel can make corresponding selections as needed.

In a possible embodiment, the transition element in the organic transition metal may be selected from at least one of Co, Ni, Ag, Cu, Pt, Cr, Nb, Nd, Ti or Mn.

Illustratively, the transition element may be selected from Nb.

In a possible embodiment, the organic iron may be selected from at least one of iron acetylacetonate or ferrous acetylacetonate.

Illustratively, the organic iron may be selected from iron acetylacetonate.

Illustratively, the organic iron may be selected from ferrous acetylacetonate.

In a possible embodiment, the organic transition metal may be selected from the group consisting of cobalt acetylacetonate, nickel acetylacetonate, silver acetylacetonate, copper acetylacetonate, platinum acetylacetonate, chromium acetylacetonate, niobium acetylacetonate, neodymium acetylacetonate, and titanium acetylacetonate. or at least one of manganese acetylacetonate.

Illustratively, the organic transition metal may be selected from niobium acetylacetonate.

Further, in the transition metal source, the molar ratio of iron element to transition element can be 1:0.01-0.4 to obtain an iron-based transition metal magnetic nanoalloy.

For example, the molar ratio of iron element to transition element may be 1:0.01, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35 or 1:0.4. one of or any range in between.

In a possible embodiment, the sulfur source is selected from at least one of thiourea, thiosemicarbazide, sodium thiosulfate, thioacetamide or L-cysteine.

Further, the molar ratio of the metal element in the transition metal source and the sulfur element in the sulfur source can be 1:0.5-2.

For example, the molar ratio of the metal element in the transition metal source and the sulfur element in the sulfur source can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1: One of 1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 2.0 or the range between any two.

Sulfur sources such as thiourea, sodium thiosulfate or thioacetamide are mixed with organic irons such as iron acetylacetonate and organic transition metals such as niobium acetylacetonate in organic amine solvents, which can react at a certain temperature to form metal sulfides. Precursors with specific morphological structures.

The precursor contains organic matter, and part or all of the organic matter comes from the organic amine solvent and its complex support.

Exemplarily, the specific morphological structure includes at least one of a one-dimensional structure, a two-dimensional structure and a three-dimensional structure.

Among them, the one-dimensional structure refers to the linear fiber structure, the two-dimensional structure refers to the sheet structure, and the three-dimensional structure refers to the block structure, such as particle structure.

Further, in order to facilitate the control of the morphology structure of the precursor, please continue to refer to Figure 1. The preparation methods provided in the examples of this application include:

S101. Preparation of one-dimensional structure

The sulfur source is selected from thioacetamide, and the organic amine solvent is selected from at least one of diethylenetriamine or hexamethylenediamine.

For example, when preparing the precursor, the preset temperature may be 180-200°C.

For example, when the sulfur source is selected from thioacetamide and the organic amine solvent is selected from diethylenetriamine, the temperature can be raised to 180°C. The preset temperature is lower than the boiling point of diethylenetriamine, and the transition metal source and sulfur can be The source basically precipitates corresponding metal ions and sulfur ions at the same time. After the reaction time is about 3 hours, the nanofiber-shaped precursor containing metal sulfide can be obtained after centrifugal cleaning and drying.

For example, when the sulfur source is selected from thioacetamide and the organic amine solvent is hexamethylenediamine, the temperature can be raised to 200°C. The preset temperature is lower than the boiling point of hexamethylenediamine, and the transition metal source and the sulfur source can be basically simultaneously The corresponding metal ions and sulfur ions are precipitated. After the reaction time is about 3 hours, the nanofiber-shaped precursor containing metal sulfide can be obtained after centrifugal cleaning and drying.

Thioacetamide can precipitate -S ^-2 in diethylenetriamine or hexamethylenediamine at a temperature of about 200°C, and can be separated from organic metal sources such as iron acetylacetonate in diethylenetriamine or hexamethylenediamine. Metal ions such as iron ions have similar temperatures and can precipitate almost simultaneously to form small seeds of metal sulfides.

Compared with sulfur sources such as sodium thiosulfate, thioacetamide and thiourea contain carbon-sulfur double bonds, with a bond energy of approximately 577kJ/mol, and a larger bond energy. In sulfur sources with high bond energy, S precipitates slowly, and the reaction tends to form one-dimensional and two-dimensional nanocrystals; while in sulfur sources with low bond energy, S precipitates quickly, forming a large number of crystal seeds, which tend to stack during the reaction. Three-dimensional structure. Moreover, thioacetamide contains amino groups, while thiourea does not contain amino groups. Thioacetamide containing amino groups tends to form one-dimensional crystals; thiourea without amino groups tends to form two-dimensional crystals.

Further, please continue to refer to Figure 1. The preparation method provided by the example of this application includes:

S102. Preparation of two-dimensional structure

The sulfur source is selected from thiourea, and the organic amine solvent is selected from triethylenetetramine; alternatively, the sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from diethylenetriamine.

For example, when the sulfur source is selected from thiourea and the organic amine solvent is selected from triethylenetetramine, the temperature can be raised to 200°C. The preset temperature is lower than the boiling point of triethylenetetramine and can make the transition metal source and thiourea basically At the same time, the corresponding metal ions and sulfur ions are precipitated. After the reaction time is about 3 hours, the nanosheet-shaped precursor containing metal sulfide can be obtained after centrifugal cleaning and drying.

For example, when the sulfur source is selected from sodium thiosulfate and the organic amine solvent is selected from diethylenetriamine, the temperature can be raised to 180°C. The preset temperature is lower than the boiling point of diethylenetriamine, and the transition metal source and sulfur can be Urea basically precipitates corresponding metal ions and sulfur ions at the same time. After a reaction time of about 3 hours, centrifugal cleaning can obtain a nanosheet-shaped precursor containing metal sulfide.

Both thioacetamide and thiourea contain carbon-sulfur double bonds with a bond energy of about 577kJ/mol, which is a relatively large bond energy. However, thiourea does not contain an amine group and sulfide ions precipitate quickly. Therefore, at around 200°C At the preset temperature, after reacting for about 3 hours, a flaky precursor can be obtained.

The bond energy of sodium thiosulfate is relatively low and it precipitates sulfide ions quickly. Under the restriction of diethylenetriamine, it can form a nanosheet precursor.

Compared with triethylenetetramine, diethylenetriamine can cooperate with sodium thiosulfate and can limit the growth of metal sulfide during the reaction to obtain a nanosheet precursor.

Further, please continue to refer to Figure 1. The preparation method provided by the example of this application includes:

S103. Preparation of three-dimensional structure

The sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from triethylenetetramine.

For example, when the sulfur source is selected from sodium thiosulfate and the organic amine solvent is selected from triethylenetetramine, the temperature can be raised to 200°C. The preset temperature is lower than the boiling point of triethylenetetramine, and the transition metal source and sulfur can be Urea basically precipitates corresponding metal ions and sulfur ions at the same time. After a reaction time of about 3 hours, centrifugal cleaning can obtain a massive precursor containing metal sulfide. Further, please continue to refer to Figure 1. The preparation method provided by the example of this application includes:

S2. Preparation of magnetic nanoalloys

Under the protection of inert gas, the precursor is reacted with a three-coordinated phosphorus compound to desulfurize and remove organic matter in the precursor to prepare the magnetic nanoalloy in situ.

The sulfur element in the precursor can be removed at high temperature by using a three-coordinated phosphorus compound to react with the precursor. At the same time, under the temperature conditions of the desulfurization reaction of the three-coordinated phosphorus compound, the organic matter in the precursor can be removed, for example, the organic amine solvent support is decomposed, and the morphology and structure of the precursor is basically consistent with the morphology and structure of the precursor, which basically does not contain sulfur elements and organic matter. Magnetic nanoalloys.

A magnetic nanoalloy whose morphology and structure is basically consistent with the precursor refers to, for example, the precursor having a one-dimensional fiber structure, and a magnetic nanoalloy with a one-dimensional fiber structure can be produced in situ; for example, the precursor has a two-dimensional sheet structure, which can be produced in-situ. Magnetic nanoalloys with a two-dimensional sheet-like structure are prepared in situ; for example, if the precursor is a three-dimensional bulk structure, a magnetic nanoalloy with a three-dimensional bulk structure can be prepared in situ.

Exemplarily, the three-coordinated phosphorus compound may be selected from at least one of tri-n-octylphosphine, tricyclohexylphosphine, trialkylphosphine, tris(4-trifluorotolyl)phosphine or tritert-butylphosphine.

For example, the three-coordinated phosphorus compound is selected from trialkyl phosphine. During the desulfurization reaction, the compound is heated to 280°C and reacted for 3 hours to obtain a magnetic nanoalloy.

Through the above preparation method, the example of this application provides a magnetic nanoalloy, including at least one of a one-dimensional structure or a two-dimensional structure. The chemical composition of the magnetic nanoalloy contains Fe element and at least one of Co, Ni, Ag, Cu, Pt, Cr, Nb, Ti or Mn elements.

Furthermore, magnetic nanoalloys can also include three-dimensional structures.

Exemplarily, the magnetic nanoalloy can be a one-dimensional nanofiber FeNb alloy, FeCo alloy, FeNi alloy, FeAg alloy, FeCu alloy, FePt alloy, FeCr alloy, FeNd alloy, FeTi alloy, FeMn alloy, FeCoNi alloy, FeCoNb alloy , FeCoNbMn alloy or FeCoNiMn alloy.

Exemplarily, the magnetic nanoalloy can be a two-dimensional nanosheet FeNb alloy, FeCo alloy, FeNi alloy, FeAg alloy, FeCu alloy, FePt alloy, FeCr alloy, FeNd alloy, FeTi alloy, FeMn alloy, FeCoNi alloy, FeCoNb alloy , FeCoNbMn alloy or FeCoNiMn alloy.

Exemplarily, the magnetic nanoalloy can be a three-dimensional bulk FeNb alloy, FeCo alloy, FeNi alloy, FeAg alloy, FeCu alloy, FePt alloy, FeCr alloy, FeNd alloy, FeTi alloy, FeMn alloy, FeCoNi alloy, FeCoNb alloy, FeCoNbMn alloy or FeCoNiMn alloy.

Furthermore, in order to facilitate the subsequent acquisition of magnetic nanoalloys with two or three structures of one-dimensional fiber structure, two-dimensional sheet structure and three-dimensional bulk structure, the corresponding one-dimensional structure precursor, two-dimensional structure can be Two or three of the three-dimensional structure precursor and the three-dimensional structure precursor are mixed, and then a desulfurization reaction is performed to remove organic matter in the precursor.

Furthermore, the examples of this application also provide a microwave absorber, which is prepared by the magnetic nanoalloy provided in the examples of this application.

For example, the magnetic nanoalloy and the epoxy resin solution can be uniformly mixed and tape-cast to obtain a microwave absorbing film.

The magnetic nanoalloy provided by the present application will be described in further detail below with reference to examples.

Example 1

Embodiment 1 provides a magnetic nanoalloy, and the preparation method is as follows:

(1) Raw material preparation: Mix 70mmol iron acetylacetonate, 30mmol niobium acetylacetonate and 100mmol sodium thiosulfate in 150mL diethylenetriamine. Pour the solution into a 250mL three-neck flask and stir vigorously until completely dissolved. The specific ingredients are shown in Table 1.

(2) Precursor preparation: Continuously pass Ar gas into the three-neck flask, and carry out the reaction in an inert gas. The mixed solution was heated to 200°C to react for 3 hours, and then cooled naturally after the reaction was completed. Centrifuge and clean to obtain the nanosheet precursor.

(3) Preparation of magnetic nanoalloy: Place 10g of the nanofiber precursor powder obtained in step (2) into 20mL of trialkylphosphine solution and stir evenly, add argon gas, and heat to 280°C for 3 hours in an argon atmosphere. After natural cooling, centrifuge and clean. The SEM picture of the product is shown in Figure 2, and two-dimensional FeNb nanosheet powder is obtained.

Example 2

The difference between Example 2 and Example 1 is that in step (1), 70 mmol iron acetylacetonate, 30 mmol niobium acetylacetonate and 100 mmol thioacetamide are mixed in 150 mL hexamethylenediamine. The specific ingredients are shown in Table 1. The SEM picture of the product is shown in Figure 3, and one-dimensional FeNb nanofiber powder is obtained.

Example 3

The difference between Example 3 and Example 1 is that in step (1), 70 mmol iron acetylacetonate, 30 mmol niobium acetylacetonate and 100 mmol sodium thiosulfate are mixed in 150 mL triethylenetetramine. The specific ingredients are shown in Table 1. The SEM image of the product is shown in Figure 4, and a three-dimensional FeNb granular powder is obtained.

Example 4

The difference between Example 4 and Example 1 is that in step (1), 70 mmol iron acetylacetonate, 30 mmol niobium acetylacetonate and 100 mmol thiourea are mixed in 150 mL triethylenetetramine. The specific ingredients are shown in Table 1. Two-dimensional FeNb nanosheet powder was obtained.

Example 5

The difference between Example 5 and Example 1 is that in step (1), 70 mmol iron acetylacetonate, 30 mmol niobium acetylacetonate and 100 mmol thioacetamide are mixed in 150 mL diethylenetriamine. The specific ingredients are shown in Table 1. One-dimensional FeNb nanofiber powder was obtained.

test case

The magnetic nanoalloys provided in Examples 1-5 were respectively prepared into 1.5mm thick films. The film prepared with Fe ₂ O ₃ micron spherical powder was used as Comparative Example 1, and the film prepared with carbonyl iron powder was used as Comparative Example 2. A film prepared from micron flake iron-nickel powder was used as Comparative Example 3. The preparation method includes: uniformly mixing 6g of target powder with 4g of epoxy resin solution, adding 10-20mg of curing agent, and casting the mixture onto a glass plate to form a film with a thickness of 1.5mm. The commercially available ferrite-filled chloroprene rubber was used as comparative example 4.

A vibrating sample magnetometer (VSM-8604) was used to test the magnetization curves of the films prepared according to Examples 1 to 5 and Comparative Example 4 respectively. The tested magnetic field intensity was -2T to 2T. The test results are shown in Figure 5. In Figure 5, the curve (a) is Example 1, the curve (b) is Example 2, the curve (c) is Example 3, the curve (d) is Example 4, the curve (e) is Example 5, ( f) The curve is Comparative Example 4.

Result analysis: Compared with the ferrite chloroprene rubber film in Comparative Example 4, the microwave absorption film prepared according to Examples 1-5 has a higher saturation magnetization (about 180 emu/g), which is much greater than that of ferrite. Saturation magnetization (about 90emu/g).

Agilent N5227B was used to test the electromagnetic properties and microwave absorption intensity of the microwave absorbing films prepared according to Examples 1-5 and the ferrite-filled epoxy resin microwave absorber of Comparative Example 4 to examine the electromagnetic wave loss performance of the microwave absorber. The test temperature is 25°C and the test frequency is 2-18GHz. The results are shown in Figure 6. In Figure 6, the curve (a) is Example 1, the curve (b) is Example 2, the curve (c) is Example 3, the curve (d) is Example 4, the curve (e) is Example 5, ( f) The curve is Comparative Example 4.

Using the above method, the electromagnetic properties and microwave absorption intensity of the microwave absorption films provided in Comparative Examples 1-3 were tested. The saturation magnetization intensity of the ferrite in Comparative Example 1 was 90emu/g, the microwave absorption intensity was -32dB, and the microwave absorption bandwidth is 5.5GHz; the saturation magnetization intensity of Comparative Example 2 is 120emu/g, the microwave absorption intensity is -45dB, and the microwave absorption bandwidth is 3GHz; the saturation magnetization intensity of Comparative Example 3 is 120emu/g, the microwave absorption intensity is -40dB, and the microwave absorption bandwidth is 3GHz. The bandwidth is 3.5GHz.

Result analysis: It can be seen from Figure 6 that compared with the ferrite rubber film in Comparative Example 4, the film prepared according to the magnetic nanoalloy provided in Examples 1-5 has higher microwave absorption intensity (RL<-50dB) and more Wide microwave absorption bandwidth (greater than 6GHz).

The above descriptions are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the protection scope of this application.

Claims (10)

1. A method for preparing a morphology-controllable magnetic nanoalloy, which is characterized by comprising: Preparing the precursor: Mix the transition metal source, the sulfur source and the organic amine solvent, raise the temperature to a preset temperature under the protection of an inert gas for reaction, separate the solid and liquid, and dry to obtain a precursor containing metal sulfide; the transition metal The source includes organic iron and organic transition metal, and the transition element in the organic transition metal is not iron; the preset temperature is not higher than the boiling point of the organic amine solvent; Preparing the magnetic nanoalloy: Under the protection of inert gas, react the precursor with a three-coordinated phosphorus compound to desulfurize, remove organic matter in the precursor, and prepare the magnetic nanoalloy in situ. 2. The preparation method according to claim 1, characterized in that the transition element in the organic transition metal is selected from at least one of Co, Ni, Ag, Cu, Pt, Cr, Nb, Nd, Ti or Mn. kind. 3. The preparation method according to claim 2, characterized in that the organic iron is selected from at least one of iron acetylacetonate or ferrous acetylacetonate; The organic transition metal is selected from at least one of cobalt acetylacetonate, nickel acetylacetonate, silver acetylacetonate, copper acetylacetonate, platinum acetylacetonate, chromium acetylacetonate, niobium acetylacetonate, neodymium acetylacetonate, titanium acetylacetonate or manganese acetylacetonate. kind. 4. The preparation method according to claim 3, wherein the sulfur source is selected from at least one of thiourea, thiosemicarbazide, sodium thiosulfate, thioacetamide, or L-cysteine. kind. 5. The preparation method according to claim 4, characterized in that the organic amine solvent is selected from at least one of diethylenetriamine, triethylenetetramine, hexamethylenediamine or propylenediamine. 6. The preparation method according to claim 5, characterized in that the three-coordinate phosphorus compound is selected from the group consisting of tri-n-octylphosphine, tricyclohexylphosphine, trialkylphosphine, tris(4-trifluorotolyl) At least one of phosphine or tri-tert-butylphosphine; Optionally, the precursor is reacted with a three-coordinated phosphorus compound to perform desulfurization, and the temperature for removing organic matter is 270-290°C, and the reaction is carried out for 2-4 hours. 7. The preparation method according to claim 6, characterized in that, in the transition metal source, the molar ratio of the iron element to the transition element is 1:0.01-0.4; The molar ratio of the element to the sulfur element in the sulfur source is 1:0.5-2; Optionally, the preset temperature is not lower than 180°C; Optionally, the preset temperature is 180-200°C. 8. The preparation method according to claim 7, characterized in that, The structure of the magnetic nanoalloy is a one-dimensional structure, the sulfur source is selected from thioacetamide, and the organic amine solvent is selected from at least one of diethylenetriamine or hexamethylenediamine; The structure of the magnetic nanoalloy is a two-dimensional structure, the sulfur source is selected from thiourea, and the organic amine solvent is selected from triethylenetetramine; alternatively, the sulfur source is selected from sodium thiosulfate, and the organic amine The solvent is selected from diethylenetriamine; The structure of the magnetic nanoalloy is a three-dimensional structure, the sulfur source is selected from sodium thiosulfate, and the organic amine solvent is selected from triethylenetetramine. 9. A magnetic nanoalloy prepared by the preparation method according to any one of claims 1 to 8, characterized in that the chemical composition of the magnetic nanoalloy includes iron and transition metal elements other than iron. At least one of the structures of the magnetic nanoalloy includes one-dimensional and/or two-dimensional structures. 10. Application of the magnetic nanoalloy according to claim 9 in the preparation of microwave absorbers.