CN114643365B - A Method of Interface-Induced Synthesis of Ordered L10 Structured Permanent Magnetic Nanoparticles - Google Patents

Abstract

The invention belongs to the technical field of magnetic nanometer materials, and in particular relates to a method for synthesizing ordered _L10 structure permanent magnetic nanoparticles by interface induction. First, add a certain proportion of seed crystal core metal precursor, surfactant and reducing agent into the solvent, heat the mixed solution to a certain temperature and keep it warm, and then cool down to room temperature, the seed crystal core metal precursor is reduced to form crystal kind of core. Then add a certain proportion of the shell metal precursor, slowly raise the temperature to a certain temperature, then keep warm and cool to room temperature, the shell metal precursor is reduced by the reducing agent, and grows under the induction of the interface of the seed core to form the shell of the L1 ₀ structure , and finally perform centrifugal cleaning to obtain a black powder of permanent magnetic nanoparticles with an ordered L1 ₀ structure. The monodisperse high coercive force ordered L1 ₀ structure nanomaterials were synthesized by ordering the metal seed interface induction, the synthesis temperature is low, and the operation is simple.

Description

A Method of Interface-Induced Synthesis of Ordered L10 Structured Permanent Magnetic Nanoparticles

Technical field:

The invention belongs to the technical field of magnetic nanometer materials, and in particular relates to a method for synthesizing ordered _L10 structure permanent magnetic nanoparticles by interface induction.

Background technique:

Some transition group intermetallic compounds have rich phase structures and diverse intrinsic magnetism, such as: FeCo and FeNi usually have A2 and B2 structures, exhibit high saturation magnetization and low coercive force, and are good soft magnetic materials; common MnAl and MnGa have a τ phase structure and exhibit ferrimagnetism. If these intermetallic compounds can be made into a chemically ordered L1 ₀ tetragonal phase, L1 ₀ -FeCo, L1 ₀ -FeNi, L1 ₀ -MnAl, L1 ₀ -MnGa, their crystal structures will have high symmetry, showing Large magnetocrystalline anisotropy, high Curie temperature and high coercive force are excellent permanent magnet materials. This type of intermetallic compound does not contain rare earth elements and is low in cost. It has broad application prospects. This type of alloy can be made into nano Particles have more important application value in high-density magnetic storage, electrochemical catalysis, micro-nano devices, and biomedicine.

However, FeCo, FeNi, MnAl, and MnGa nanoparticles usually prepared directly are difficult to obtain ordered tetragonal phases with high magnetocrystalline anisotropy, because the process window for obtaining alloys with this structure is very narrow, such as: L1 ₀ -MnAl It is a metastable phase formed by quenching and subsequent annealing (usually at 500°C) of the Mn-rich ε phase, which is easily decomposed into a non-magnetic phase. The L1 ₀ -FeNi phase diffuses slowly at the order-disorder transition temperature of 593K, and L1 ₀ -FeNi only exists in meteorites that have been cooled at extremely low cooling rates for billions of years. L1 ₀ -FeCo has more desirable magnetic properties than L1 ₀ -FeNi, but due to the limited understanding of the thermodynamics of phase formation, the preparation of L1 ₀ -FeCo remains to be studied, and so far, L1 has not been successfully synthesized in any laboratory ₀ -FeCo phase. However, the existing chemical synthesis methods generally directly reduce the metal precursors, and the atoms form FeCo, FeNi, MnAl or MnGa alloy nuclei in a certain reaction environment, and then grow into FeCo, FeNi, MnAl or MnGa nanoparticles. , Metal atoms are randomly stacked, so it is difficult to control the formation of an ordered structure, so it is difficult to prepare FeCo, FeNi, MnAl, and MnGa nanomaterials with L1 ₀ structure by ordinary processes. How to induce orderly growth of atoms in the process of nucleation and growth, and prepare L1 ₀ -FeCo, FeNi, MnAl, MnGa nanoparticles with good controllability and high degree of order is the bottleneck problem in this field.

Invention content:

The purpose of the present invention is to provide a method for interface-induced synthesis of ordered L1 ₀ structure permanent magnet nanoparticles, the order L1 ₀ structure permanent magnet nanoparticles of the present invention refers to transition group intermetallic compound nanoparticles, especially through It is difficult to form intermetallic compounds with an ordered L1 ₀ structure by conventional methods, specifically, permanent magnetic nanoparticles of intermetallic compounds such as FeCo, FeNi, MnAl, and MnGa.

The design of the patent of the present invention is as follows:

Nanoparticles such as FeCo, FeNi, MnAl, and MnGa with the L1 ₀ structure are difficult to obtain by direct synthesis, so they need to be induced to form an ordered structure during the synthesis process. Chemically synthesized nanoparticles are usually carried out in the form of nucleation and growth. Firstly, crystal nuclei are formed, and then grow into large-sized particles or various nanomaterials. During the growth process, usually different atoms will stack along the surface of the crystal nucleus, and epitaxial growth along the interface is the main growth mode, so the structure of the crystal nucleus is hereditary to the synthesized nanoparticles. If seeds with the L1 ₀ structure are put into the reaction system, these seeds serve as heterogeneous nucleation particles, and these reduced atoms are stacked along the surface of the seed crystal core. When the lattice constant of the seed crystal is the same as that of the The lattice constants of the particles are close, and their lattice lattices have a high degree of matching, and these atoms will grow epitaxially along the original crystal plane, thereby continuing to grow into nanoparticles with an ordered L1 ₀ structure.

Intermetallic compounds such as AuCu, MnNi, and FePt exist stably at lower temperatures and are easily obtained by chemical synthesis, and their lattice lattices are similar to those of ordered L1 ₀ -FeCo, FeNi, MnAl, and MnGa High matching degree, easy to form epitaxial growth. Therefore, AuCu, MnNi, and FePt with L1 ₀ structure can be synthesized first as seed crystals, and then these transition group intermetallic compounds with ordered L1 ₀ structure can be obtained by using these seeds as the core and through the interface induction of their lattices ( For example, permanent magnetic nanoparticles of FeCo, FeNi, MnAl, MnGa, etc. as described above.

The permanent magnetic nanoparticles formed in this way have intermetallic compound seeds such as AuCu, MnNi, and FePt with L1 ₀ structure as the core, and transition group intermetallic compounds such as FeCo, FeNi, MnAl, and MnGa with L1 ₀ structure as the outer shell. The morphology, degree of order, and magnetic properties of the product can be controlled by controlling the volume ratio, controlling the chemical composition of the product, and changing the reaction temperature and reaction time.

To achieve the above object, the present invention adopts a method for synthesizing permanent magnetic nanoparticles with ordered L1 ₀ structure by interface induction. First, add a certain proportion of seed crystal core metal precursor, surfactant and reducing agent into the solvent, heat the mixed solution to a certain temperature and keep it warm, and then cool down to room temperature, the seed crystal core metal precursor is reduced to form L1 ₀ structure of AuCu, MnNi, FePt and other intermetallic compound seed core. Then add a certain proportion of FeCo, FeNi, MnAl or MnGa shell metal precursor, slowly heat up to a certain temperature, then remove the heating source after keeping warm, cool to room temperature, the shell metal precursor is reduced by the reducing agent, and in the core of the seed crystal Growth is induced by the interface to form a FeCo, FeNi, MnAl or MnGa shell with an L1 ₀ structure, and finally centrifuged to obtain a black powder of permanent magnetic nanoparticles with an ordered L1 ₀ structure.

The inventive method specifically comprises the following steps:

S1: Weigh the seed core metal precursor and reducing agent.

The seed crystal core metal precursor is a metal source mixture of two metals capable of forming an L1 ₀ metal alloy with a highly ordered structure, and can generate a seed crystal core with an L1 ₀ structure after reduction. Specifically, the intermetallic compound or metal alloy as the seed core can be AuCu, MnNi, FePt, so the seed core metal precursor can be gold source and copper source, manganese source and nickel source or iron source and platinum source The mixture of metal ions in the two metal sources is preferably (0.1～1):(0.1～1) in molar ratio.

Specifically, in the seed crystal core metal precursor: the gold source is one or more of chloroauric acid HAuCl ₄ , potassium tetrachloroaurate KAuCl ₄ ; the copper source is copper acetylacetonate Cu(acac) ₂ , acetic acid One or more of copper Cu(Ac) ₂ , copper chloride CuCl ₂ ; manganese source is one or more of manganese acetate Mn(Ac) ₂ , manganese chloride MnCl ₂ , manganese acetylacetonate Mn(acac) ₂ The nickel source is one or more of nickel acetate Ni(Ac) ₂ , nickel nitrate Fe(NO ₃ ) ₃ , nickel sulfate Fe ₂ (SO ₄ ) ₃ , nickel chloride NiCl ₂ , nickel acetylacetonate Ni(acac) ₂ species; iron source is one or more of ferric chloride FeCl ₃ , ferric nitrate FeNO ₃ , ferric sulfate Fe ₂ (SO ₄ ) ₃ , iron acetylacetonate Fe(acac) ₃ ; platinum source is chloroplatinic acid H ₂ PtCl _6. One or more of platinum acetylacetonate Pt(acac) ₂ , potassium chloride platinum acid K ₂ PtCl ₆ .

The reducing agent is one of potassium borohydride KBH ₄ , sodium borohydride NaBH ₄ , 1,2-hexadecanediol C ₁₆ H ₃₄ O ₂ , lithium aluminum hydride LiAlH, sodium cyanoborohydride CH ₃ BNNa or several. The actual total addition amount of the reducing agent is not less than the theoretical addition amount, and the theoretical addition amount of the reducing agent is an amount capable of reducing all metal ions in the seed crystal core metal precursor and the shell metal precursor to zero-valent metals. Specifically, the ratio of the actual addition amount of the reducing agent to the theoretical addition amount may be (1-10):1.

S2: adding the seed crystal core metal precursor into the solvent, performing water removal treatment under the action of a protective atmosphere, and adding a surfactant after the water removal treatment to form a mixed solution.

Preferably, the solvent is hexadecylamine C ₁₆ H ₃₅ N, trioctylamine C ₂₄ H ₅₁ N, octadecylamine C ₁₈ H ₃₉ N, eicosylamine C ₂₀ H ₄₃ N, oleylamine C ₁₈ H ₃₇ N One or more of them, the surfactant is brominated quaternary amine C ₁₆ H ₃₈ Br ₂ N ₂ , lecithin C ₄₂ H ₈₀ NO ₈ P, glyceryl monostearate C ₂₁ H ₄₂ O ₄ , The two substances in oleylamine C ₁₈ H ₃₇ N and oleic acid C ₁₈ H ₃₄ O ₂ are mixed, and the two substances of surfactant are mixed according to the volume ratio (0.1-1): (0.1-1) and then added. The above-mentioned solvents and surfactants can promote the metal atoms generated after the reduction of the seed core metal precursor to grow into an L1 ₀ structure more favorably, and also promote the metal atoms of the shell metal precursor to be better in the core of the seed crystal. L1 ₀ structure was grown under the induction of lattice interface. The solvent provides a good platform for the growth of the two, and the surfactant can retain the surface activity of the synthesized L1 ₀ structure to the greatest extent, and the various groups existing on the surface provide guarantee for various subsequent applications.

The molar ratio of the metal ion to the solvent in the seed core metal precursor is 1: (10-30), and the molar ratio of the solvent to the surfactant (the surfactant is the total amount of the two substances) is 10: (1.0-5.0 ).

Preferably, the protective atmosphere is one of 93% Ar+7% H ₂ , 95% Ar+5% H ₂ , high-purity argon Ar or high-purity nitrogen N ₂ . The method of water removal treatment is as follows: under the action of a protective atmosphere, the temperature is raised to 100-120° C. at a heating rate of 1-10° C./min and kept for 30-120 minutes. Water removal treatment is more conducive to the role of surfactants.

S3: Heating the mixed solution to the first reaction temperature and keeping it warm, performing a reaction to form a seed crystal core, cooling down, weighing and adding the shell metal precursor.

During the heating and heat preservation process, the seed core metal precursors were reduced to 0-valent metal atoms and assembled into intermetallic compounds to form the seed core of L1 ₀ structure. Therefore, before this process, that is, before the reaction of generating seed crystal cores, it is necessary to ensure that there is a sufficient amount of reducing agent in the solution.

Preferably, the first reaction temperature is 280-360° C., the holding time is 30-300 minutes, and the mixed solution is cooled to 60-120° C. after the reaction.

The shell metal precursor is a metal source mixture of two metals that constitute the ordered L10 structure permanent magnetic nanoparticles to be prepared, such as FeCo, FeNi, MnAl or _MnGa , so specifically, the shell metal precursor can be Fe source and a source of cobalt, a source of iron and a source of nickel, a source of manganese and a source of aluminum or a source of manganese and a source of gallium.

As mentioned above, these metals are usually difficult to form intermetallic compounds or alloy nanoparticles with an ordered L1 ₀ structure, but in the present invention, under the premise that the seed core exists and the interface is induced, this The difficulty of forming intermetallic compounds of the structure is greatly reduced.

Preferably, the molar ratio of the two metal ions in the outer shell metal precursor metal source is (0.2-1): (0.2-1). In the shell metal precursor, the iron source is one or more of iron chloride FeCl ₃ , iron carbonyl Fe(CO) ₅ , iron acetylacetonate Fe(acac) ₃ , iron oleate C ₅₄ H ₉₉ FeO ₆ ; The cobalt source is one or more of cobalt acetylacetonate Co(acac) ₂ , dicobalt octacarbonyl Co ₂ (CO) ₈ , and cobalt acetate Co(Ac) ₂ ; the nickel source is nickel acetate Ni(Ac) ₂ , nitric acid One or more of nickel Fe(NO ₃ ) ₃ , nickel sulfate Fe ₂ (SO ₄ ) ₃ , nickel chloride NiCl ₂ , nickel acetylacetonate Ni(acac) ₂ ; manganese source is manganese acetate Mn(Ac) ₂ , One or more of manganese chloride MnCl ₂ and manganese acetylacetonate Mn(acac) ₂ ; the aluminum source is one or more of aluminum chloride AlCl ₃ and aluminum acetylacetonate Al(acac) ₃ ; the gallium source is gallium acetate One or more of Ga(Ac) ₂ , gallium chloride GaCl ₂ , gallium acetylacetonate Ga(acac) ₂ .

When adding the shell metal precursor to the mixed solution, the molar ratio of the total amount of metal ions in the shell metal precursor to the total amount of metal ions in the seed core metal precursor is (0.4-1): (0.2-1) .

S4: Heating the mixed solution to the second reaction temperature and keeping it warm, performing a reaction to form a shell, and then cooling to room temperature, and performing centrifugal cleaning on the mixed solution to obtain black powder, that is, the ordered L1 ₀ structure permanent magnetic nanoparticles.

During this heating and holding process, the shell metal precursors are reduced to 0-valent metal atoms, and an intermetallic compound with an ordered L1 ₀ structure is formed under the interface induction of the seed core. Therefore, before this process, that is, before the reaction to form the shell, it is necessary to ensure that the mixed solution contains a sufficient amount of reducing agent.

Preferably, the second reaction temperature is 200-300° C., and the holding time is 10-60 minutes.

Preferably, in the steps S3 and S4, the mixed solution is heated up to the reaction temperature by a slow temperature rise method with a temperature rise rate of 1-10°C/min, so as to ensure sufficient reduction of the precursor and make the intermetallic compound sufficiently growth time.

The following describes a method of centrifugally cleaning the mixed solution to obtain a black powder:

Use two mixed solvents for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform by volume ratio (1-5): (5-1), mixed solvent B is deionized water and absolute ethanol by volume ratio (1-5): a mixed solvent of (5-1).

First, wash the mixed solution with mixed solvent A, the volume ratio of mixed solvent A: mixed solution is (1-5): 1, then perform centrifugation, and pour off the upper liquid after centrifugation to obtain black powder;

Then wash the black powder with mixed solvent A and centrifuge, repeat 3 to 5 times;

Then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder alternately. The process of washing with mixed solvent B and then centrifuging + washing with mixed solvent A is called 1 time, and repeat this process 3 to 5 times. ;

Finally, the black powder after the last cleaning and centrifugation was stored in absolute ethanol.

In the above method, the rotational speed of the centrifuge for centrifugation is 6000-12000 rpm, and the centrifugation time is 3-10 minutes each time.

In the above method, it is introduced that in the reaction of forming the seed crystal core and forming the shell in step S3 and step S4, it is necessary to ensure that there is a sufficient amount of reducing agent in the mixed solution. Specifically, the reducing agent is added by one of the following two methods:

Method A: adding all the reducing agent before the reaction of generating the seed crystal core in step S3, for example, all the reducing agent can be added into the solvent together with the seed crystal core metal precursor in step S2.

Method B: Add the first part of the reducing agent before the reaction of generating the seed crystal core in step S3. For example, a solvent can be added together with the seed crystal core metal precursor. The amount, the second part of the remaining reducing agent is added before the reaction of forming the shell in step S4, for example, it can be added together with the shell metal precursor to ensure the complete reduction of the shell metal precursor.

Through the above method, ordered L1 ₀ structure nanoparticles can be successfully synthesized by interface induction, and the order degree of the product is 0.85-0.95. The coercive force Hc reaches 850.5-1500.8Oe, and the saturation magnetization Ms reaches 61.2-185.8emu/g.

Beneficial effects of the present invention:

(1) Monodisperse high-coercivity ordered L1 ₀ structured nanomaterials were synthesized through ordered metal seed interface induction, with low synthesis temperature and simple operation;

(2) By optimizing the synthesis process, ordered L1 ₀ structure nanomaterials with excellent dispersion, high degree of order and excellent magnetic properties can be obtained;

(3) The purpose of the present invention is to use interface induction to prepare highly ordered L1 ₀ structured nanoparticles, to avoid aggregation and abnormal growth during heat treatment, and to provide theoretical support and promote practical use for the preparation of highly ordered L1 ₀ structured nanomaterials process.

Description of drawings:

Fig. 1 is the XRD collection of illustrative plates of the synthesis product of embodiment 1 of the method of the present invention;

Fig. 2 is the hysteresis loop of the synthesis product of the method embodiment 1 of the present invention;

Fig. 3 is the TEM image of the synthetic product of the method embodiment 1 of the present invention;

Fig. 4 is the XRD collection of illustrative plates of the synthetic product of embodiment 2 of the method of the present invention;

Fig. 5 is the hysteresis loop of the synthetic product of the method embodiment 2 of the present invention;

Fig. 6 is the TEM image of the synthetic product of the method embodiment 2 of the present invention;

Fig. 7 is the XRD pattern of the synthesis product of the method embodiment 3 of the present invention;

Fig. 8 is the hysteresis loop of the synthetic product of the method embodiment 3 of the present invention;

Fig. 9 is a TEM image of the product synthesized in Example 3 of the method of the present invention.

Detailed ways:

The present invention will be described in further detail below in conjunction with embodiment.

In the following examples:

Experimental equipment, instruments, and experimental reagents were purchased commercially.

Experimental equipment and instruments include: three-necked flask, condenser tube, electronic balance, mechanical stirring heating mantle and centrifuge, etc.;

Experimental reagents include: chloroauric acid, potassium tetrachloroaurate, copper acetylacetonate, copper acetate, copper chloride, manganese acetate, manganese chloride, manganese acetylacetonate, nickel acetate, nickel nitrate, nickel sulfate, nickel chloride, acetyl Nickel acetone, ferric chloride, ferric nitrate, ferric sulfate, ferric acetylacetonate, chloroplatinic acid, platinum acetylacetonate, potassium chloroplatinate, carbonyl iron, ferric oleate, cobalt acetylacetonate, dicobalt octacarbonyl, cobalt acetate, acetic acid Nickel, nickel nitrate, nickel sulfate, nickel chloride, nickel acetylacetonate, manganese acetate, manganese chloride, manganese acetylacetonate, manganese chloride, aluminum acetylacetonate, gallium acetate, gallium chloride, gallium acetylacetonate, potassium borohydride, Sodium borohydride, 1,2-hexadecanediol, lithium aluminum hydride, sodium cyanoborohydride, hexadecylamine, trioctylamine, octadecylamine, eicosylamine, oleylamine, oleic acid, 93% Ar+ 7% H ₂ , 95% Ar+5% H ₂ , high-purity argon Ar, high-purity nitrogen N ₂ , chloroform, absolute ethanol, and deionized water were purchased from the market.

The magnetic properties of the product were measured by vibrating sample magnetometer (VSM), the morphology of the product was observed by field emission transmission electron microscope (TEM), and the phase of the product was analyzed by X-ray diffraction (XRD).

In the following examples, the reducing agent is added by one of the following two methods:

Method A: All reducing agents are added before the reaction for generating seed crystal cores, for example, all reducing agents can be added to the solvent together with the seed crystal core metal precursor in step S2.

Method B: Add the first part of the reducing agent before the reaction of generating the seed crystal core. For example, the solvent can be added together with the seed crystal core metal precursor. The amount of the first part added is not less than the amount that can completely reduce the seed crystal core metal precursor. A second part of the remaining reducing agent is added before the reaction for forming the outer shell in step S4 to ensure complete reduction of the outer shell metal precursor.

As long as the reducing agent can ensure that the metal sources in the seed crystal core metal precursor and the shell metal precursor can be fully reduced in the two reactions of generating the seed crystal core and the shell metal precursor, the specific details of the reducing agent are not specifically described in the following examples. Only the type and amount of addition are recorded.

Example 1:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor copper acetylacetonate and gold source chloroauric acid, the molar ratio of the two is 0.3:0.2, and weigh the reducing agent 1,2-hexadecane di For alcohol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:1.

(2) Add the weighed seed crystal core metal precursor powder (copper source + gold source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent hexadecylamine, wherein the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of a protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 120° C. at a heating rate of 10° C./min and kept at 120° C. for 120 minutes to remove moisture, and then a surfactant (oleylamine + oleic acid) was added to the mixed solution. By volume, oleylamine: oleic acid = 1:1; by molar ratio, solvent: surfactant = 10:1.0.

(3) Slowly heat up the mixed solution to 280°C for 300 minutes at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, add shell metal precursor powder iron source ferric chloride and The cobalt source is cobalt acetylacetonate, the molar ratio of the metal in the shell metal precursor powder and the seed core metal precursor powder is 1:0.5, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated to 300° C. at a heating rate of 1° C./min, then kept at a temperature of 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol ; The centrifuge speed of the centrifugal separation is 12000 rpm, and each centrifugation time is 10min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.92. The XRD pattern is shown in Figure 1. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1175.6Oe , and the saturation magnetization Ms was 89.9emu/g. The hysteresis loop is shown in Figure 2. The morphology of the product was observed by a field emission transmission electron microscope as a uniformly dispersed core-shell morphology, and the TEM image is shown in Figure 3. Comparative literature Nano Letters 2014, 14, 6493-6498. The coercive force of the core-shell nanoparticles obtained by heat treatment at 380°C is 846 Oe, which is similar to the result in this example.

Example 2:

(1) First, use an electronic balance to weigh the seed core metal precursor copper acetate and gold source potassium tetrachloroaurate, the molar ratio of the two is 0.5:0.2, and weigh a certain amount of reducing agent potassium borohydride, The ratio between the theoretical value and the actual value of the amount of reducing agent is 1:1.

(2) Add the weighed seed crystal core metal precursor powder (copper source+gold source) and reducing agent potassium borohydride into a three-necked flask equipped with solvent trioctylamine, wherein the seed crystal core metal precursor and The molar ratio of solvents is 1:15. Under the protective atmosphere of 95% Ar+5% H ₂ , the temperature was raised to 100° C. for 120 minutes at a heating rate of 1° C./min to remove moisture, and then the surfactant (brominated quaternary ammonium bromide+oleic acid) Add the mixed solution, by volume ratio, quaternary ammonium bromide:oleic acid=1:0.5; by molar ratio, solvent:surfactant=10:2.0.

(3) Slowly heat up the mixed solution to 290°C for 200 minutes at a heating rate of 2°C/min to obtain a black mixed solution, then cool it to 120°C, and add shell metal precursor powder iron source carbonyl iron and cobalt to the mixed solution The source is dicobalt octacarbonyl, the metal molar ratio of the shell metal precursor powder and the seed core metal precursor powder is 1:0.2, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.2.

(4) The mixed solution was heated up to 270° C. at a heating rate of 2° C./min, then kept for 10 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:2, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 3:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 2:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugal separation is 8000-12000 rpm, and the centrifugation time is 3 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.90. The XRD pattern is shown in Figure 4. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1028.9Oe , and the saturation magnetization Ms was 91.0emu/g. The hysteresis loop is shown in Figure 5. The morphology of the product was observed by a field emission transmission electron microscope as a uniformly dispersed core-shell morphology, and the TEM image is shown in Figure 6. Comparative literature Nano Letters 2014, 14, 6493-6498. The coercive force of the core-shell nanoparticles obtained by heat treatment at 380°C is 846 Oe, which is similar to the result in this example.

Example 3:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor copper source copper chloride and gold source chloroauric acid, the molar ratio of the two is 0.1:1, and weigh a certain amount of reducing agent sodium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:2.

(2) Add the weighed seed crystal core metal precursor powder (copper source + gold source) and reducing agent sodium borohydride into a three-necked flask equipped with solvent trioctylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:20. Under the action of high-purity argon Ar in the protective atmosphere, the temperature was raised to 105°C at a heating rate of 2°C/min and kept for 100 minutes to remove moisture, and then the surfactant (brominated quaternary ammonium bromide + oleic acid) was added to the mixed solution , by volume ratio, quaternary ammonium bromide:oleic acid=0.4:1; by molar ratio, solvent:surfactant=10:3.0.

(3) Slowly heat up the mixed solution to 300°C for 250 minutes at a heating rate of 3°C/min to obtain a black mixed solution, then cool it to 100°C, add shell metal precursor powder iron source iron acetylacetonate and The cobalt source is cobalt acetate, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.7, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.5.

(4) The mixed solution was heated to 260° C. at a heating rate of 5° C./min, then kept for 20 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:4, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 5:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 3:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 4 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugal separation is 8000-10000 rpm, and the centrifugation time is 4-8 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.91. The XRD pattern is shown in Figure 7. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1093.1Oe , and the saturation magnetization Ms was 76.4emu/g. The hysteresis loop is shown in Figure 8. The morphology of the product was observed by a field emission transmission electron microscope as a uniformly dispersed core-shell morphology, and the TEM image is shown in Figure 9. Comparative literature Nano Letters 2014, 14, 6493-6498. The coercive force of the core-shell nanoparticles obtained by heat treatment at 380°C is 846 Oe, which is similar to the result in this example.

Example 4:

(1) First, use an electronic balance to weigh the seed core metal precursor copper acetylacetonate and gold source potassium tetrachloroaurate, the molar ratio of the two is 0.5:1, and weigh a certain amount of reducing agent1,2 - For cetanediol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:2.

(2) Add the weighed seed crystal core metal precursor powder (copper source + gold source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent octadecylamine, wherein the seed crystal The molar ratio of core metal precursor and solvent is 1:25. Under the action of high-purity nitrogen _N2 in the protective atmosphere, the temperature was raised to 110°C at a heating rate of 10°C/min and kept at 110°C for 80 minutes to remove moisture, and then surfactants (oleylamine + lecithin) were added to the mixed solution. , oleylamine: lecithin = 0.3: 1; in molar ratio, solvent: surfactant = 10: 4.0.

(3) Slowly heat up the mixed solution to 320°C for 150 minutes at a heating rate of 5°C/min to obtain a black mixed solution, then cool it to 90°C, add shell metal precursor powder iron source iron oleate and The cobalt source is cobalt acetylacetonate, the metal molar ratio of the shell metal precursor powder and the seed core metal precursor powder is 1:0.5, and the molar ratio of the two metal ions in the shell metal precursor is 1:1.

(4) The mixed solution was heated up to 200° C. at a heating rate of 1° C./min, then kept for 30 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 4:5, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 5:4; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 4:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 4 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 8000-10000 rpm, and the centrifugation time is 6-8 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.95. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer, and its coercive force Hc was _1405.5Oe , and the saturation magnetization Ms was 92.5emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 5:

(1) First use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese acetate and nickel source nickel acetate, the molar ratio of the two is 0.3:1, and weigh a certain amount of reducing agent lithium aluminum hydride, the amount of reducing agent The ratio between theoretical value and actual value is 1:3.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and reducing agent lithium aluminum hydride into a three-necked flask equipped with solvent eicosamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:30. Under the action of high-purity argon Ar in a protective atmosphere, the temperature was raised to 115°C at a heating rate of 5°C/min and kept for 50 minutes to remove moisture, and then the surfactant (oleylamine + glyceryl monostearate) was added to the mixed solution , by volume, oleylamine:glyceryl monostearate=1:0.3; by molar ratio, solvent:surfactant=10:5.0.

(3) Slowly heat up the mixed solution to 340°C for 100 minutes at a heating rate of 8°C/min to obtain a black mixed solution, then cool to 80°C, and add shell metal precursor powder nickel source nickel acetate and iron to the mixed solution The source iron oleate, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.4, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:1.

(4) The mixed solution was heated up to 245° C. at a heating rate of 8° C./min, then kept for 40 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 2:5, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 5:2; first The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 5:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is washed with mixed solvent A and removed Centrifuge, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugal separation is 8000-10000 rpm, and the centrifugation time is 3-10 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.95. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer, and its coercive force Hc was _1405.5Oe , and the saturation magnetization Ms was 92.5emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Embodiment 6:

(1) First use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese chloride and nickel source nickel nitrate, the molar ratio of the two is 1:0.5, and weigh a certain amount of reducing agent sodium cyanoborohydride, The ratio between the theoretical value and the actual value of the amount of reducing agent is 1:4.

(2) Add the weighed seed crystal core metal precursor powder (manganese source+nickel source) and reducing agent sodium cyanoborohydride into a three-necked flask equipped with solvent oleylamine, wherein the seed crystal core metal precursor and The molar ratio of solvents is 1:25. Under the protection atmosphere 95% Ar + ₅ % H Under the action, be heated up to 120 ℃ and keep warm for 30min with the heating rate of 8 ℃/min, carry out dehydration treatment, then surfactant (brominated decalkane quaternary ammonium+lecithin) Add the mixed solution, by volume, quaternary ammonium bromide:lecithin=1:1; by mole ratio, solvent:surfactant=10:2.0.

(3) Slowly heat up the mixed solution to 360°C for 30 minutes at a heating rate of 10°C/min to obtain a black mixed solution, then cool it to 60°C, and add shell metal precursor powder iron source iron acetylacetonate and The nickel source is nickel nitrate, the metal molar ratio of the shell metal precursor powder and the seed core metal precursor powder is 1:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.2:1.

(4) The mixed solution was heated up to 240° C. at a heating rate of 10° C./min, then kept for 50 minutes, and cooled to room temperature to obtain a black mixed solution.

Adopt two kinds of mixed solvents to carry out centrifugal cleaning, mixed solvent A is the mixed solvent of absolute ethanol and chloroform by volume ratio 1:5, mixed solvent B is the mixed solvent of deionized water and absolute alcohol by volume ratio 5:1; First The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 5:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is washed with mixed solvent A and removed Centrifugal separation, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugal separation is 6000-12000 rpm, and the centrifugation time is 3-10 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.95. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1500.8Oe , and the saturation magnetization Ms was 85.6emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Embodiment 7:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese acetylacetonate and nickel source nickel sulfate, the molar ratio of the two is 1:0.2, and weigh a certain amount of reducing agent 1,2-16 For alkanediol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:3.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent cetylamine, in which the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of a protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 100° C. at a heating rate of 1° C./min and kept for 30 minutes to remove moisture, and then a surfactant (oleylamine + oleic acid) was added to the mixed solution. By volume, oleylamine: oleic acid = 1:1; by molar ratio, solvent: surfactant = 10:1.0.

(3) Slowly heat up the mixed solution to 280°C for 30 minutes at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, and add shell metal precursor powder iron source carbonyl iron and nickel to the mixed solution The source of nickel sulfate, the metal molar ratio of the shell metal precursor powder and the seed core metal precursor powder is 0.8:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated up to 280° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 1:5, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The centrifuge rotating speed of described centrifugation is 6000rpm, and each centrifugation time is at 3min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.86. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _896.8Oe , and the saturation magnetization Ms was 163.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Embodiment 8:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese chloride and nickel source nickel chloride, the molar ratio of the two is 0.5:1, and weigh a certain amount of reducing agent potassium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:7.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and reducing agent potassium borohydride into a three-necked flask equipped with solvent octadecylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:30. Under the action of high-purity argon in the protective atmosphere, the temperature was raised to 120°C at a heating rate of 10°C/min and kept at 120°C for 120 minutes to remove moisture, and then surfactants (oleylamine + lecithin) were added to the mixed solution. Oleylamine:lecithin=0.1:1; in molar ratio, solvent:surfactant=10:5.0.

(3) Slowly heat up the mixed solution to 360°C for 300 minutes at a heating rate of 10°C/min to obtain a black mixed solution, then cool it to 120°C, add shell metal precursor powder iron source ferric chloride and The nickel source is nickel chloride, the metal molar ratio of the shell metal precursor powder and the seed crystal core metal precursor powder is 1:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.2:1.

(4) The mixed solution was heated up to 340° C. at a heating rate of 10° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 1:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:1; first The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 5:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is washed with mixed solvent A and removed Centrifuge, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder alternately, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol ; The centrifuge speed of the centrifugal separation is 12000 rpm, and each centrifugation time is 10min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.89. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1096.8Oe , and the saturation magnetization Ms was 185.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Embodiment 9:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese acetylacetonate and nickel source nickel acetylacetonate, the molar ratio of the two is 0.8:1, and weigh a certain amount of reducing agent sodium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:2.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and reducing agent sodium borohydride into a three-necked flask equipped with solvent trioctylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:20. Under the action of high-purity nitrogen in a protective atmosphere, the temperature was raised to 110°C at a heating rate of 5°C/min and kept for 75 minutes to remove moisture, and then a surfactant (quaternary ammonium bromide + oleic acid) was added to the mixed solution. Volume ratio, decacene quaternary ammonium bromide:oleic acid=1:0.1; molar ratio, solvent:surfactant=10:3.0.

(3) Slowly heat up the mixed solution to 320°C for 150 minutes at a heating rate of 5°C/min to obtain a black mixed solution, then cool it to 90°C, add shell metal precursor powder iron source iron oleate and The nickel source is nickel acetylacetonate, the metal molar ratio of the shell metal precursor powder and the seed core metal precursor powder is 1:0.7, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.2.

(4) The mixed solution was heated up to 300° C. at a heating rate of 5° C./min, then kept at a temperature of 30 minutes, and cooled to room temperature to obtain a black mixed solution.

Adopt two kinds of mixed solvents to carry out centrifugal cleaning, mixed solvent A is the mixed solvent of absolute ethanol and chloroform by volume ratio 5:1, mixed solvent B is the mixed solvent of deionized water and absolute alcohol by volume ratio 5:1; First Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 4 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The centrifuge rotating speed of described centrifugation is 9000rpm, and each centrifugation time is at 6min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.90. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer, and its coercive force Hc was _1206.7Oe , and the saturation magnetization Ms was 61.2emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 10:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese acetate and nickel source nickel chloride, the molar ratio of the two is 0.7:1, and weigh a certain amount of reducing agent sodium cyanoborohydride, The ratio between the theoretical value and the actual value of the amount of reducing agent is 1:1.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and reducing agent sodium cyanoborohydride into a three-necked flask equipped with solvent eicosamine, wherein the seed crystal core metal precursor The molar ratio of solvent and solvent is 1:10. Under protective atmosphere 93%Ar+7%H _2Under the effect, be that 10 ℃/min heat up to 120 ℃ and keep warm for 120min with the heating rate, carry out dehydration treatment, then surfactant (oleylamine+glyceryl monostearate) Add the mixed solution, by volume, oleylamine:glyceryl monostearate=1:1; by molar ratio, solvent:surfactant=10:1.0.

(3) Slowly heat up the mixed solution to 280°C for 300 minutes at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, and add the shell metal precursor powder manganese source manganese acetate and aluminum to the mixed solution The source of aluminum chloride, the metal molar ratio of the shell metal precursor powder and the seed crystal core metal precursor powder is 0.4:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated up to 280° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifugal separation, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 6000-12000 rpm, and the centrifugation time is 10 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnAl, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.92. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1231.8Oe , and the saturation magnetization Ms was 75.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 11:

(1) First, use an electronic balance to weigh the core metal precursor gold source chloroauric acid and copper source copper chloride, the molar ratio of the two is 1:0.7, and weigh a certain amount of reducing agent 1,2-deca For hexanediol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:6.

(2) Add the weighed seed crystal core metal precursor powder (gold source + copper source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent cetylamine, in which the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of a protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 120°C at a heating rate of 8°C/min and kept at 120°C for 120min to remove moisture, and then a surfactant (oleylamine+oleic acid) was added to the mixed solution, By volume, oleylamine: oleic acid = 1:1; by molar ratio, solvent: surfactant = 10:1.0.

(3) Slowly raise the temperature of the mixed solution to 280°C for 300min at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, and add the shell metal precursor powder manganese source manganese chloride and The aluminum source is aluminum chloride, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.6, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.2.

(4) The mixed solution was heated up to 280° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The centrifuge rotating speed of described centrifugation is 9000rpm, and each centrifugation time is 10min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnAl, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.93. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force H _c was 1332.7 Oe, and the saturation magnetization Ms was 71.5 emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 12:

(1) First, use an electronic balance to weigh the core metal precursor gold source potassium tetrachloroaurate and the copper source copper acetylacetonate, the molar ratio of the two is 1:0.2, and weigh a certain amount of reducing agent 1,2 - Hexadecane glycol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:9.

(2) Add the weighed seed crystal core metal precursor powder (gold source + copper source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent cetylamine, in which the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of a protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 100° C. at a heating rate of 1° C./min and kept for 30 minutes to remove moisture, and then a surfactant (oleylamine + oleic acid) was added to the mixed solution. By volume, oleylamine: oleic acid = 1:1; by molar ratio, solvent: surfactant = 10:1.0.

(3) Slowly heat up the mixed solution to 280°C for 30 minutes at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, add shell metal precursor powder manganese source manganese acetylacetonate and The aluminum source is aluminum acetylacetonate, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 0.8:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated up to 280° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 1:5, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The centrifuge rotating speed of described centrifugation is 6000rpm, and each centrifugation time is at 3min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnAl, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.94. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1231.8Oe , and the saturation magnetization Ms was 75.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 13:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor iron source ferric chloride and platinum source platinum acetylacetonate, the molar ratio of the two is 0.5:1, and weigh a certain amount of reducing agent potassium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:2.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and reducing agent potassium borohydride into a three-necked flask equipped with solvent octadecylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:30. Under the action of high-purity argon in the protective atmosphere, the temperature was raised to 120°C at a heating rate of 10°C/min and kept at 120°C for 120 minutes to remove moisture, and then surfactants (oleylamine + lecithin) were added to the mixed solution. Oleylamine:lecithin=0.1:1; in molar ratio, solvent:surfactant=10:5.0.

(3) Slowly heat up the mixed solution to 360°C for 300 minutes at a heating rate of 10°C/min to obtain a black mixed solution, then cool it to 120°C, add shell metal precursor powder manganese source manganese acetylacetonate and The gallium source is gallium acetate, the molar ratio of the metals in the shell metal precursor powder to the seed core metal precursor powder is 1:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.2:1.

(4) The mixed solution was heated up to 340° C. at a heating rate of 10° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 1:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:1; first The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 5:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is washed with mixed solvent A and removed Centrifugal separation, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol ; The centrifuge speed of the centrifugal separation is 12000 rpm, and each centrifugation time is 10min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnGa, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.95. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1450.5Oe , and the saturation magnetization Ms was 85.9emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 14:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor iron source iron nitrate and platinum source chloroplatinic acid, the molar ratio of the two is 0.8:1, and weigh a certain amount of reducing agent sodium borohydride, reducing agent The ratio between theoretical value and actual value is 1:2.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and reducing agent sodium borohydride into a three-necked flask equipped with solvent trioctylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:20. Under the action of high-purity nitrogen in a protective atmosphere, the temperature was raised to 110°C at a heating rate of 5°C/min and kept for 75 minutes to remove moisture, and then a surfactant (quaternary ammonium bromide + oleic acid) was added to the mixed solution. Volume ratio, decacene quaternary ammonium bromide:oleic acid=1:0.1; molar ratio, solvent:surfactant=10:3.0.

(3) Slowly heat up the mixed solution to 320°C for 150 minutes at a heating rate of 5°C/min to obtain a black mixed solution, then cool to 90°C, and add shell metal precursor powder manganese source manganese acetate and gallium to the mixed solution Source gallium chloride, the metal molar ratio of the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.7, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.2.

(4) The mixed solution was heated up to 300° C. at a heating rate of 5° C./min, then kept at a temperature of 30 minutes, and cooled to room temperature to obtain a black mixed solution.

Adopt two kinds of mixed solvents to carry out centrifugal cleaning, mixed solvent A is the mixed solvent of absolute ethanol and chloroform by volume ratio 5:1, mixed solvent B is the mixed solvent of deionized water and absolute alcohol by volume ratio 5:1; First Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 4 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The centrifuge rotating speed of described centrifugation is 9000rpm, and each centrifugation time is at 6min.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnGa, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.90. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1460.8Oe , and the saturation magnetization Ms was 160.5emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 15:

(1) First use an electronic balance to weigh the seed core metal precursor iron source iron sulfate and platinum source potassium chloroplatinate, the molar ratio of the two is 0.7:1, and weigh a certain amount of reducing agent sodium cyanoborohydride , The ratio between the theoretical value and the actual value of the amount of reducing agent is 1:6.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and reducing agent sodium cyanoborohydride into a three-necked flask equipped with solvent eicosamine, wherein the seed crystal core metal precursor The molar ratio of solvent and solvent is 1:10. Under protective atmosphere 93%Ar+7%H _2Under the effect, be that 10 ℃/min heat up to 120 ℃ and keep warm for 120min with the heating rate, carry out dehydration treatment, then surfactant (oleylamine+glyceryl monostearate) Add the mixed solution, by volume, oleylamine:glyceryl monostearate=1:1; by molar ratio, solvent:surfactant=10:1.0.

(3) Slowly raise the temperature of the mixed solution to 280°C for 300min at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 60°C, and add the shell metal precursor powder manganese source manganese chloride and The gallium source is gallium acetylacetonate, the molar ratio of the metals in the shell metal precursor powder to the seed core metal precursor powder is 0.4:1, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated up to 200° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifugal separation, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 6000-12000 rpm, and the centrifugation time is 10 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnGa, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.92. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1492.4Oe , and the saturation magnetization Ms was 126.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 16:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor iron acetylacetonate and platinum source chloroplatinic acid, the molar ratio of the two is 0.2:0.3, and weigh a certain amount of reducing agent 1,2-deca For hexanediol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:4.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent hexadecylamine, in which the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of a protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 100° C. at a heating rate of 1° C./min and kept for 120 minutes to remove moisture, and then a surfactant (oleylamine + oleic acid) was added to the mixed solution. By volume, oleylamine:oleic acid=0.2:1; by molar ratio, solvent:surfactant=10:1.0.

(3) Slowly heat up the mixed solution to 280°C for 200 minutes at a heating rate of 10°C/min to obtain a black mixed solution, then cool it to 60°C, and add manganese source powder manganese acetate and gallium to the mixed solution The source gallium acetylacetonate, the metal molar ratio of the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.5, and the molar ratio of the two metal ions in the shell metal precursor is 0.5:0.5.

(4) The mixed solution was heated up to 280° C. at a heating rate of 10° C./min, then kept for 15 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 5:1, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 1:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 6000-12000 rpm, and the centrifugation time is 10 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnGa, which contains ordered phase characteristic peaks (001), (110) and (002), and the order degree is 0.91. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1358.6Oe , and the saturation magnetization Ms was 143.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 17:

(1) First, use an electronic balance to weigh the seed core metal precursor iron source iron sulfate and platinum source potassium chloroplatinate, the molar ratio of the two is 0.2:1, and weigh a certain amount of reducing agent potassium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:1.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and reducing agent potassium borohydride into a three-necked flask equipped with solvent trioctylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:10. Under the action of protective atmosphere 95% Ar + 5% H ₂ , the temperature was raised to 120° C. for 100 minutes at a heating rate of 3° C./min, and the water removal treatment was carried out, and then the surfactant (brominated quaternary ammonium bromide + oleic acid) was added For the mixed solution, by volume ratio, decacene quaternary ammonium bromide:oleic acid=0.8:1; by molar ratio, solvent:surfactant=10:4.1.

(3) Slowly heat up the mixed solution to 320°C for 300 minutes at a heating rate of 7°C/min to obtain a black mixed solution, then cool it to 120°C, add shell metal precursor powder iron source ferric chloride and The cobalt source is cobalt acetylacetonate, the molar ratio of the metal in the shell metal precursor powder and the seed core metal precursor powder is 1:0.8, and the molar ratio of the two metal ions in the shell metal precursor is 0.2:1.

(4) The mixed solution was heated up to 220° C. at a heating rate of 1° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Adopt two kinds of mixed solvents to carry out centrifugal cleaning, mixed solvent A is the mixed solvent of absolute ethanol and chloroform by volume ratio 1:5, mixed solvent B is the mixed solvent of deionized water and absolute alcohol by volume ratio 5:1; First The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 5:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is washed with mixed solvent A and removed Centrifugal separation, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol ; The rotational speed of the centrifuge for the centrifugal separation is 6000-12000 rpm, and the centrifugation time is 3-4 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.93. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force H _c was 1434.5 Oe, and the saturation magnetization Ms was 120.7 emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 18:

(1) First, use an electronic balance to weigh the seed core metal precursor gold source chloroauric acid and copper source copper acetylacetonate, the molar ratio of the two is 1:0.4, and weigh a certain amount of reducing agent sodium borohydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:3.

(2) Add the weighed seed crystal core metal precursor powder (gold source + copper source) and reducing agent sodium borohydride into a three-necked flask equipped with solvent octadecylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:10. Under the action of high-purity argon Ar in the protective atmosphere, the temperature was raised to 110°C at a heating rate of 5°C/min and kept for 30 minutes, and the moisture was removed. , oleylamine: lecithin = 1:0.1; in molar ratio, solvent: surfactant = 10:3.8.

(3) Slowly heat up the mixed solution to 360°C for 100 minutes at a heating rate of 9°C/min to obtain a black mixed solution, then cool it to 110°C, add shell metal precursor powder iron source ferric chloride and The cobalt source is cobalt acetylacetonate, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.8, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.9.

(4) The mixed solution was heated up to 240° C. at a heating rate of 7° C./min, then kept for 10 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 3:4, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 1:4; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 2:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 4 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol ; The rotational speed of the centrifuge for the centrifugal separation is 7000-10000 rpm, and the centrifugation time is 3-7 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.86. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _952.8Oe , and the saturation magnetization Ms was 85.2emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 19:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor manganese source manganese acetate and nickel source nickel acetylacetonate, the molar ratio of the two is 1:0.1, and weigh a certain amount of reducing agent 1,2-16 For alkanediol, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:5.

(2) Add the weighed seed crystal core metal precursor powder (manganese source + nickel source) and the reducing agent 1,2-hexadecanediol into a three-necked flask containing the solvent eicosamine, in which the seed crystal The molar ratio of core metal precursor and solvent is 1:10. Under the action of high-purity nitrogen _N2 in the protective atmosphere, the temperature was raised to 117°C at a heating rate of 7°C/min and kept for 70 minutes to remove moisture, and then the surfactant (oleylamine + glyceryl monostearate) was added to the mixed solution , by volume, oleylamine:glyceryl monostearate=1:0.5; by molar ratio, solvent:surfactant=10:1.9.

(3) Slowly heat up the mixed solution to 300°C for 20 minutes at a heating rate of 1°C/min to obtain a black mixed solution, then cool it to 90°C, add shell metal precursor powder iron source ferric chloride and The cobalt source is cobalt acetylacetonate, the molar ratio of the metal in the shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.8, and the molar ratio of the two metal ions in the shell metal precursor is 1:0.2.

(4) The mixed solution was heated up to 260° C. at a heating rate of 5° C./min, then kept for 40 minutes, and cooled to room temperature to obtain a black mixed solution.

Adopt two kinds of mixed solvents to carry out centrifugal cleaning, mixed solvent A is the mixed solvent of absolute ethanol and chloroform by volume ratio 5:2, mixed solvent B is the mixed solvent of deionized water and absolute alcohol by volume ratio 4:1; First Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 3:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 4 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder alternately, repeat 5 times; finally store the black powder after the last cleaning and centrifugation in absolute ethanol ; The rotational speed of the centrifuge for the centrifugal separation is 7000-8000 rpm, and the centrifugation time is 5-7 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeCo, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.93. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer, and its coercive force Hc was _1168.4Oe , and the saturation magnetization Ms was 106.8emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 20:

(1) First, use an electronic balance to weigh the seed crystal core metal precursor iron source ferric chloride and platinum source chloroplatinic acid, the molar ratio of the two is 0.9:1, and weigh a certain amount of reducing agent lithium aluminum hydride, reduce The ratio between the theoretical value and the actual value of dosage is 1:3.

(2) Add the weighed seed crystal core metal precursor powder (iron source + platinum source) and reducing agent lithium aluminum hydride into a three-necked flask equipped with solvent oleylamine, wherein the seed crystal core metal precursor and solvent The molar ratio is 1:10. Under the protective atmosphere of 93% Ar+7% H ₂ , the temperature was raised to 105°C at a rate of 10°C/min and kept at 105°C for 50min, followed by dehydration treatment, followed by addition of surfactant (brominated decacene quaternary ammonium+lecithin) For the mixed solution, by volume ratio, decacene quaternary ammonium bromide:lecithin=1:0.1; by molar ratio, solvent:surfactant=10:5.0.

(3) Slowly heat up the mixed solution to 340°C for 30 minutes at a heating rate of 3°C/min to obtain a black mixed solution, then cool it to 70°C, add shell metal precursor powder iron source ferric chloride and The nickel source is nickel nitrate, the metal molar ratio of the shell metal precursor powder to the seed core metal precursor powder is 1:0.8, and the molar ratio of the two metal ions in the shell metal precursor is 0.9:1.

(4) The mixed solution was heated up to 265° C. at a heating rate of 4° C./min, then kept for 60 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 3:5, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 2:5; first Wash the mixed solution by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 4:1, then perform centrifugation, pour off the upper liquid after centrifugation, and obtain a black powder; then wash the black powder with mixed solvent A and remove Centrifuge, repeat 5 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 3 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 9000 rpm, and the centrifugation time is 5-9 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -FeNi, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.93. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer. The coercive force Hc was _1069.5Oe , and the saturation magnetization Ms was 86.5emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

Example 21:

(1) First, use an electronic balance to weigh the core metal precursor gold source potassium tetrachloroaurate and the copper source copper acetylacetonate, the molar ratio of the two is 0.3:0.8, and weigh a certain amount of reducing agent cyanoboron For sodium hydride, the ratio between the theoretical value and the actual value of the amount of reducing agent is 1:1.

(2) Add the weighed seed crystal core metal precursor powder (gold source + copper source) and reducing agent sodium cyanoborohydride into a three-necked flask equipped with solvent hexadecylamine, wherein the seed crystal core metal precursor The molar ratio of solvent and solvent is 1:10. Under the action of a protective atmosphere of 95% Ar + 5% H ₂ , the temperature was raised to 113° C. at a heating rate of 8° C./min and kept for 60 minutes to remove moisture, and then a surfactant (oleylamine + oleic acid) was added to the mixed solution. By volume, oleylamine:oleic acid=0.8:1; by molar ratio, solvent:surfactant=10:2.2.

(3) Slowly raise the temperature of the mixed solution to 350°C for 120min at a heating rate of 4°C/min to obtain a black mixed solution, then cool it to 80°C, and add shell metal precursor powder manganese source manganese acetylacetonate and Gallium source gallium chloride, the metal molar ratio of the outer shell metal precursor powder and the seed crystal core metal precursor powder is 1:0.4, and the molar ratio of the two metal ions in the outer shell metal precursor is 0.5:1.

(4) The mixed solution was heated up to 235° C. at a heating rate of 9° C./min, then kept for 50 minutes, and cooled to room temperature to obtain a black mixed solution.

Two kinds of mixed solvents are used for centrifugal cleaning, mixed solvent A is a mixed solvent of absolute ethanol and chloroform in a volume ratio of 2:3, and mixed solvent B is a mixed solvent of deionized water and absolute alcohol in a volume ratio of 3:2; first The mixed solution is cleaned by mixed solvent A, the volume ratio of mixed solvent A: mixed solution is 3.2:1, and then centrifuged, after centrifuged, the upper liquid is poured off to obtain a black powder; then the black powder is cleaned with mixed solvent A and removed Centrifugal separation, repeat 3 times; then use mixed solvent B and mixed solvent A to wash and centrifuge the black powder in turn, repeat 5 times; finally, store the black powder after the last cleaning and centrifugation in absolute ethanol The rotational speed of the centrifuge for the centrifugation is 7500-10000 rpm, and the centrifugation time is 6-9 minutes each time.

The phase of the product characterized by X-ray diffraction is L1 ₀ -MnGa, which contains ordered phase characteristic peaks (001), (110) and (002), and the degree of order is 0.92. The hysteresis loop of the product at room temperature was measured by a vibrating sample ferromagnetometer, and its coercive force Hc was _1086.7Oe , and the saturation magnetization Ms was 96.5emu/g. The morphology of the product was observed by field emission transmission electron microscopy as a uniformly dispersed core-shell morphology.

It can be seen from the above examples that L1 ₀ -FeCo, L1 ₀ -FeNi, L1 ₀ -MnAl, L1 ₀ -MnGa nanomaterials have been successfully synthesized by using ordered nanoparticle interface induction, and the core-shell nanomaterials have excellent dispersion properties, high degree of order and excellent magnetic properties.

Claims (4)

1. Interface induction synthesis orderL1 ₀ A method of structuring permanent magnetic nanoparticles, comprising the steps of:

s1: weighing a seed crystal core metal precursor and a reducing agent;

s2: adding a seed crystal core metal precursor into a solvent, performing dehydration treatment under the action of a protective atmosphere, and adding a surfactant after the dehydration treatment to form a mixed solution; the solvent is hexadecylamine C ₁₆ H ₃₅ N, trioctylamine C ₂₄ H ₅₁ N, octadecylamine C ₁₈ H ₃₉ N, icosanamine C ₂₀ H ₄₃ One or more of N; the surfactant is decabromodecaHydrocarbon quaternary amine C ₁₆ H ₃₈ Br ₂ N ₂ Lecithin C ₄₂ H ₈₀ NO ₈ P, glyceryl monostearate C ₂₁ H ₄₂ O ₄ And oleic acid C ₁₈ H ₃₄ O ₂ Mixing the two substances in the (1), wherein the two substances of the surfactant are mixed according to a volume ratio of (0.1 to 1): (0.1 to 1) and adding the mixture; the molar ratio of metal ions to solvent in the seed crystal core metal precursor is 1: (10 to 30), wherein the molar ratio of the solvent to the surfactant is 10: (1.0 to 5.0); said protective atmosphere being 93% Ar +7% ₂ 、95%Ar + 5%H ₂ High purity nitrogen N ₂ One kind of (1);

the method for dewatering treatment comprises the steps of heating to 100-120 ℃ at a heating rate of 1-10 ℃/min for 30-120 min under the action of a protective atmosphere;

s3: heating the mixed solution to a first reaction temperature, preserving heat, carrying out a reaction for generating a seed crystal core, cooling, weighing and adding a shell metal precursor; the first reaction temperature is 280-360 ℃, the heat preservation time is 30-300 min, and the cooling temperature is 60-90 ℃;

s4: heating the mixed solution to a second reaction temperature, preserving heat, carrying out a shell generation reaction, cooling to room temperature, and carrying out centrifugal cleaning on the mixed solution to obtain black powder, namely the ordered powderL1 ₀ Structural permanent magnetic nanoparticles; the second reaction temperature is 240 to 300 ℃, and the heat preservation time is 40 to 60min;

the seed crystal core metal precursor can form a highly ordered structureL1 ₀ Metal source mixture of two metals of a metal alloy capable of forming a highly ordered structureL1 ₀ The two metals of the metal alloy are AuCu, mnNi or FePt; the molar ratio of two metal ions in the seed crystal core metal precursor is (0.1-1): (0.1 to 1);

the shell metal precursor is structured to be prepared in orderL1 ₀ Metal source mixture of two metals of structured permanent magnetic nanoparticles, said composition constituting the order to be producedL1 ₀ Two metals of the structural permanent magnetic nano particle are FeCo, feNi, mnAl or MnGa; in the metal precursor of the housingThe molar ratio of the two metal ions is (0.2 to 1): (0.2 to 1);

the molar ratio of the total amount of metal ions in the shell metal precursor to the total amount of metal ions in the seed crystal core metal precursor is (0.4 to 1): (0.2 to 1);

the total adding amount of the reducing agent is not less than the theoretical adding amount, and the theoretical adding amount of the reducing agent is the adding amount of the reducing agent capable of completely reducing the seed crystal core metal precursor and the shell metal precursor;

in the step S3 and the step S4, the temperature of the mixed solution is raised to the reaction temperature, and the heating rate is 1 to 10 ℃/min.

2. The interface-induced synthetic order of claim 1L1 ₀ A method of structuring permanent magnetic nanoparticles, characterized by:

in the seed core metal precursor: the gold source is potassium tetrachloroaurate KAuCl ₄ The copper source is copper acetate Cu (Ac) ₂ Copper chloride (CuCl) ₂ The manganese source is manganese acetate Mn (Ac) ₂ Manganese chloride MnCl ₂ Manganese acetylacetonate Mn (acac) ₂ The nickel source is nickel acetate Ni (Ac) ₂ Nickel nitrate Fe (NO) ₃ ) ₃ Nickel sulfate Fe ₂ (SO ₄ ) ₃ Nickel chloride NiCl ₂ Nickel acetylacetonate Ni (acac) ₂ The iron source is one or more of ferric chloride FeCl ₃ FeNO, iron nitrate ₃ Iron (Fe) sulfate ₂ (SO ₄ ) ₃ Fe acetylacetonate (acac) ₃ One or more of (A), the platinum source is chloroplatinic acid H ₂ PtCl ₆ Platinum acetylacetonate Pt (acac) ₂ Chloroplatinic acid K ₂ PtCl ₆ One or more of (a);

in the shell metal precursor: the iron source is ferric chloride FeCl ₃ Fe acetylacetonate (acac) ₃ C, iron oleate ₅₄ H ₉₉ FeO ₆ One or more of the above; the cobalt source is cobalt acetylacetonate Co (acac) ₂ Cobalt acetate Co (Ac) ₂ One or more of the above; the nickel source is nickel acetate Ni (Ac) ₂ Nickel nitrate Fe (NO) ₃ ) ₃ Nickel sulfate Fe ₂ (SO ₄ ) ₃ Nickel chloride NiCl ₂ Nickel acetylacetonate Ni (acac) ₂ One or more of (a); the manganese source is manganese acetate Mn (Ac) ₂ Manganese chloride MnCl ₂ Manganese acetylacetonate Mn (acac) ₂ One or more of (a); the aluminum source is aluminum chloride AlCl ₃ Aluminum acetylacetonate Al (acac) ₃ One or more of (a); the gallium source is gallium acetate Ga (Ac) ₂ Gallium chloride GaCl ₂ Ga acetylacetonate (acac) ₂ One or more of (a).

3. The interface-induced synthetic ordering of claim 1L1 ₀ The method for preparing the structural permanent magnetic nano particle is characterized in that the reducing agent is potassium borohydride KBH ₄ Sodium borohydride NaBH ₄ Lithium aluminum hydride LiAlH, sodium cyanoborohydride CH ₃ One or more of BNNa; the reducing agent is added by one of the following two methods:

the method A comprises the following steps: adding all reducing agents before the reaction of generating the seed crystal cores in the step S3;

the method B comprises the following steps: a first portion of the reducing agent is added before the seed core generation reaction of step S3, the first portion being added in an amount not less than the amount of the reducing agent capable of reducing the seed core metal precursor in its entirety, and a second portion of the remaining reducing agent is added before the shell generation reaction of step S4.

4. The interface-induced synthetic order of claim 1L1 ₀ The method for preparing the structural permanent magnetic nanoparticles is characterized in that the method for obtaining the black powder by centrifugally cleaning the mixed solution in the step S4 comprises the following steps:

carrying out centrifugal cleaning by adopting two mixed solvents, wherein the mixed solvent A is absolute ethyl alcohol and chloroform according to a volume ratio of (1 to 5): (5 to 1), wherein the mixed solvent B is deionized water and absolute ethyl alcohol in a volume ratio of (1 to 5): (5 to 1) a mixed solvent;

first, the mixed solution is washed by a mixed solvent a: the volume ratio of the mixed solution is (1 to 5): 1, then carrying out centrifugal separation, and pouring out upper liquid after the centrifugal separation to obtain black powder;

then cleaning the black powder by using a mixed solvent A, carrying out centrifugal separation, and repeating for 3 to 5 times;

then cleaning and centrifugally separating the black powder by adopting a mixed solvent B and a mixed solvent A in turn, and repeating for 3 to 5 times; finally, storing the black powder after the last cleaning and centrifugal separation in absolute ethyl alcohol;

the rotation speed of the centrifugal machine for centrifugal separation is 6000 to 12000rpm, and the time for each centrifugation is 3 to 10min.

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