CN108526482B

CN108526482B - Magnetic alloy hollow microsphere and preparation method thereof

Info

Publication number: CN108526482B
Application number: CN201810338114.5A
Authority: CN
Inventors: 童国秀; 刘琳; 孙嘉诚; 乔儒; 陈锦绣; 宫培军; 韩佳女; 胡潘冰; 吴文华
Original assignee: Zhejiang Normal University CJNU
Current assignee: Zhejiang Normal University CJNU
Priority date: 2018-04-11
Filing date: 2018-04-11
Publication date: 2021-05-04
Anticipated expiration: 2038-04-11
Also published as: CN108526482A

Abstract

The invention relates to a magnetic alloy hollow microsphere and a preparation method thereof. The microsphere comprises cobalt and nickel, and has a structure formula of Co_xNi_1‑xWherein: x is more than or equal to 0.14 and less than or equal to 1; has a hollow structure, the diameter of which is 0.32 to 3.35 mu m, and the wall thickness of which is 4 to 370 nm; the saturation magnetization is 80.4-152.89 emu g^–1. The microsphere is prepared by adopting a mixed solvent high-temperature liquid phase reduction method: adding an organic solvent, water and a surfactant into a three-neck flask according to a certain ratio, and stirring for 10 minutes; then adding metal salt and stirring for 2 hours, dropping reducing agent and stirring for 1 hour, then condensing and refluxing for 3-4 hours at the temperature of 170-197 ℃, cooling, then carrying out magnetic separation and washing for multiple times by using ethanol, and finally drying to obtain the required magnetic alloy hollow microspheres. The invention has the advantages of cheap and easily obtained raw materials, low cost, simple process, high efficiency and easy popularization; the magnetic ball chain has the characteristics of adjustable size and composition and the like, and can be applied to magneto-rheological, magnetic separation, catalysis, electrode materials, microwave absorption or high-density magnetic recording materials.

Description

Magnetic alloy hollow microsphere and preparation method thereof

Technical Field

The invention relates to the field of nanotechnology, in particular to a simple method for preparing magnetic alloy hollow microspheres.

Background

The magnetic metal nano material has unique electrical, optical and magnetic properties and excellent chemical properties, and is widely applied to the aspects of nuclear magnetic resonance imaging, optical nano devices, targeted drugs, magnetic storage, catalysts and the like. Among them, the hollow magnetic micro-nano material is concerned by its characteristics of low density, high specific surface area, low thermal expansion coefficient and refractive index. The method for preparing the hollow microspheres mainly comprises the traditional hard template method, the sacrificial template synthesis method, the soft template preparation method and the template-free method. At present, only a few documents and patents report the preparation of magnetic metal/alloy hollow microspheres. Chinese patent document (CN201510083390.8) discloses a hard template method for preparing a nickel-based amorphous hollow microsphere alloy catalyst. Chinese patent document (CN105206373A) discloses a method for preparing a magnetic composite microsphere with a multilevel structure by assembling a magnetic metal nano-array structure on the surface of a hollow microsphere. Chinese patent document (CN102319903A) discloses a preparation method of hollow microspheres, which uses microspherical alloy powder with the component of AxB (1-x) (x is more than or equal to 0.4 and less than 1) as a raw material, firstly forms a layer of oxide micro-film through pre-oxidation treatment, and deposits the component A and the component B in calcination and evaporation on the surface of a sphere wall to form composite hollow microspheres containing metal and metal oxide. And further reducing or dissolving to obtain the metal hollow microsphere. Chinese patent document (CN101294055) discloses a preparation method of coating a metal coating layer on the surface of a hollow microsphere by using a chemical plating process. Chinese patent document (CN101941076A) discloses a method for preparing a multilayer hollow metal microsphere for an electromagnetic wave absorbing material, which adopts an inner layer hollow Ni sphere obtained by autocatalytic reduction reaction; the single-layer or multi-layer Co, Fe metal or Co1-xFex alloy film is coated on the surface of the Ni hollow sphere through chemical plating, and the thickness is adjustable. The method adopts a hard template, high-temperature calcination or chemical plating process, so that the defects of complicated multiple steps, high-temperature energy consumption, special requirements on equipment, long period, harsh conditions and the like exist. Therefore, the development of a simple one-step template-free method becomes a new direction for research of researchers.

In order to overcome the problems existing in the method, the magnetic alloy hollow microspheres are prepared by adopting a one-step mixed solvent high-temperature liquid phase reduction method, and the formation of the magnetic alloy hollow microspheres is attributed to the etching action of water and the Oswald curing mechanism. The size and the composition of the particles can be regulated and controlled by the temperature of the liquid phase reduction reaction, the reaction time, the amount of the surfactant, the water, the feed ratio of the cobalt to the nickel metal salt and the like. The magnetic alloy hollow microsphere has the characteristics of good dispersibility, adjustable size and composition and the like, and has wide application prospect in the fields of magnetic rheology, magnetic separation, catalysis, electrode materials, high-density magnetic recording materials, microwave absorption, drug transmission, biomedical imaging and the like.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the simple method of the magnetic alloy hollow microsphere with controllable size and composition is provided, and the magnetic alloy hollow microsphere obtained by the method has stronger magnetic responsiveness and excellent microwave absorption characteristic. The synthesis method has the advantages of simple and easy preparation process, low temperature, low energy consumption, cheap and easily-obtained raw materials, novel preparation flow, unique formation mechanism, no need of a template, low cost, good repeatability and easy popularization.

The invention adopts the following technical scheme for solving the technical problems:

the magnetic alloy hollow microsphere provided by the invention comprises the effective components of Co and Ni, and the structural formula of the magnetic alloy hollow microsphere is Co_xNi_1-xWherein: x is more than or equal to 0.14 and less than or equal to 1; has a hollow structure, the diameter of which is 0.32 to 3.35 mu m, and the wall thickness of which is 4 to 370 nm; the saturation magnetization is 80.4-152.89 emu g^-1。

The preparation method of the magnetic ball chain provided by the invention adopts a mixed solvent high-temperature liquid phase reduction method for preparation, and specifically comprises the following steps: adding an organic solvent, water and a surfactant into a three-neck flask according to a certain ratio, and stirring for 10 minutes; and then adding metal salt, stirring for 2 hours under an electric condition, then dropwise adding a reducing agent, stirring for 1 hour under an electric condition, then carrying out condensation reflux at the temperature of 170-197 ℃ for 3-4 hours, cooling, then carrying out magnetic separation and washing for multiple times by using ethanol, and finally drying to obtain the required magnetic alloy hollow microspheres.

In the method, the concentration of the metal salt is 0.045-0.18 mol per liter, the mass fraction of the surfactant is 6-12 g per liter, the volume ratio of the reducing agent to the total amount of the metal salt is 0.556-2.778 ml per millimole, and the volume ratio of the deionized water to the organic solvent is 3.5:99-6.5: 96.

The reducing agent adopts anhydrous hydrazine hydrate or 50-85% of hydrazine hydrate in volume fraction.

The metal salt is one of cobalt and nickel chloride salt and acetate.

The organic solvent is glycol or glycerol.

The mass ratio of the cobalt salt to the nickel salt is 1: (0-4).

The surfactant is polyvinylpyrrolidone (PVP).

In the method, the magnetic hollow microspheres are formed by adopting a magnetic field induction and an Oswald curing mechanism, have a hollow structure, have the diameter of 0.32-3.35 mu m and have the wall thickness of 4-370 nm.

The magnetic hollow microsphere provided by the invention has the saturation magnetization of 80.4-152.89 emu.g^-1And controllable in size and composition.

The magnetic hollow microsphere provided by the invention is applied to magnetorheological, magnetic separation, catalysis, electrode materials, microwave absorption or high-density magnetic recording materials.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects:

(1) the preparation process is simple and feasible, one-step synthesis, low temperature, short time, low energy consumption and good repeatability;

(2) the preparation process is novel, the formation mechanism is unique, and a template is not needed;

(3) the magnetic hollow microspheres have controllable size and composition and good dispersibility;

(4) the raw materials are cheap and easy to obtain, the preparation cost is low, the efficiency is high, and the industrial application and popularization are easy.

Drawings

FIGS. 1, 3, 8, 10, 12, 14 to 19 and 21 to 26 are respectively the morphologies of the products obtained in examples 1, 2, 3, 4, 5 to 10 and 11 to 16 observed under a scanning electron microscope.

FIG. 2 is an elemental composition analysis of the products obtained in examples 1-4 observed under a scanning electron microscope.

FIGS. 1 and 20 are XRD phase structure diagrams of products obtained in examples 1 to 4 and 10 to 11, respectively.

FIGS. 5 to 6 show the electromagnetic parameters of the products obtained in examples 1 to 4, respectively.

FIG. 4 shows the static magnetic properties of the products obtained in examples 1 to 4.

FIGS. 7, 9, 11 and 13 show the microwave absorption characteristics of the products obtained in examples 1 to 4, respectively.

Detailed Description

The magnetic alloy hollow microsphere is formed by utilizing the etching action of water and an Oswald curing mechanism. The size and the composition of the particles can be regulated and controlled by regulating the temperature of the mixed solvent high-temperature liquid-phase reduction reaction, the reaction time, the amount of the surfactant, the water, the feed ratio of the cobalt to the nickel metal salt and the like. The method has the advantages of cheap and easily-obtained raw materials, low cost, simple process, low requirement on equipment, high efficiency and easy popularization.

For a better understanding of the invention, the following examples and drawings are included to further illustrate the invention, but the invention is not limited to the following examples.

The magnetic alloy hollow microsphere provided by the invention comprises the components of Co and Ni, and the structural formula of the magnetic alloy hollow microsphere is Co_xNi_1-xWherein: x is more than or equal to 0.14 and less than or equal to 1; has a hollow structure, the diameter of which is 0.32 to 3.35 mu m, and the wall thickness of which is 4 to 370 nm; the saturation magnetization is 80.4-152.89 emu g^-1。

The magnetic alloy hollow microsphere provided by the invention has the characteristics of hollow or porous structure, adjustable size and composition and the like, and can be prepared by the following embodiment method.

Example 1:

firstly, 1.2g (12g/L) of surfactant [ polyvinylpyrrolidone (PVP)]Dissolved in a mixed solution of 98mL of pure ethylene glycol and 4.5mL of deionized water, stirred uniformly, and 0.6424g (0.027M) of CoCl was added₂·6H₂O and 0.4279g (0.018M) NiCl₂·6H₂O is stirred for 2 hours under electric power, then 2.5mL of anhydrous hydrazine hydrate is added into the solution and stirredAnd (4) 1 h. And heating the mixture to 197 ℃ for boiling, condensing and refluxing for four hours, cooling, then carrying out magnetic separation and washing for multiple times by using absolute ethyl alcohol until the solution is clear, and finally drying to obtain the required magnetic alloy hollow microspheres.

The phase, the element composition and the appearance of the product observed under a scanning electron microscope are shown in figures 1-3, the particle diameter is 0.72-1.68 mu m, and the wall thickness is 28-73 nm; energy spectrum analysis As shown in FIG. 2, the Co/Ni atomic ratio was 1.96; the static magnetic property is shown in FIG. 4, and the saturation magnetization is 110.03emu g^-1. The electromagnetic parameters are shown in figures 5-6, the real part and the imaginary part of the dielectric constant are respectively increased by 2.22-2.38 and 2.13-5.52 times relative to the hollow Co ball in the frequency range of 2-18 GHz, and the real part and the imaginary part of the magnetic conductivity are respectively increased by 0.79-0.94 and 0.22-0.75 time relative to the hollow Co ball. The two-dimensional reflectivity is shown in FIG. 7, the paraffin is used as the substrate, the mass fraction is 42%, the reflectivity is 4.32GHz, and the reflectivity is-42.34 dB when the sample thickness is 4.9 mm.

Example 2:

the procedure of example 1 was followed except that only 1.0706g (0.045M) of CoCl was added to the solution₂·6H₂And O, the appearance of the obtained product observed under a scanning electron microscope is shown in figure 8, the particle diameter is 0.84-1.85 mu m, and the wall thickness is 4-17 nm. The static magnetic property is shown in FIG. 5, and the saturation magnetization is 152.89emu g^-1(ii) a The two-dimensional reflectivity is shown in FIG. 9, the two-dimensional reflectivity is as shown by using paraffin as the substrate, the reflectivity is-18.08 dB at 2GHz when the mass fraction is 50% and the reflectivity is-18.08 dB when the thickness of the sample is 7.9 mm.

Example 3:

the procedure of example 1 was followed, except that 0.5353g (0.0225M) of CoCl was added to the solution at the same time₂·6H₂O and 0.5348g (0.0225M) NiCl₂·6H₂And O. The appearance of the obtained product observed under a scanning electron microscope is shown in figure 10, the particle diameter is 0.76-1.82 mu m, and the wall thickness is 47-78 nm. The energy spectrum analysis is shown in FIG. 2, and the Co/Ni atomic ratio is 1.69. The static magnetic property is shown in FIG. 5, and the saturation magnetization is 105.93emu g^-1(ii) a The electromagnetic parameters are shown in figures 5-6, the real part and the imaginary part of the dielectric constant are respectively increased by 0.75-1.39 times and 0.21-0.79 times relative to the hollow Co ball in the frequency range of 2-18 GHz, and the real part and the imaginary part of the magnetic conductivity are respectively increasedCompared with the addition of 0.98-1.02 times and 0.11-0.96 times respectively. The two-dimensional reflectivity is shown in FIG. 11, the two-dimensional reflectivity is as-51.5 dB when the paraffin is used as the substrate and the mass fraction is 50% and the reflectivity is 5.44GHz when the sample thickness is 3.9 mm.

Example 4:

the procedure of example 1 was followed, except that 0.2141g (0.009M) of CoCl was added simultaneously to the solution₂·6H₂O and 0.8557g (0.036M) NiCl₂·6H₂And O. The appearance of the obtained product observed under a scanning electron microscope is shown in figure 12, the particle diameter is 1.08-1.98 mu m, and the wall thickness is 84-137 nm. The energy spectrum analysis is shown in FIG. 2, and the Co/Ni atomic ratio is 0.16. The static magnetic property is shown in FIG. 5, and the saturation magnetization is 80.4emu g^-1. The electromagnetic parameters are shown in figures 5-6, the real part and the imaginary part of the dielectric constant are increased by 1.32-1.58 and 1.11-2.35 times relative to the hollow Co ball in the frequency range of 2-18 GHz respectively, and the real part and the imaginary part of the magnetic conductivity are increased by 0.97-0.98 and 0.52-1.21 times relative to the hollow Co ball respectively. The two-dimensional reflectivity is shown in FIG. 13, the two-dimensional reflectivity is-13.92 dB when the mass fraction is 50% and the reflectivity is 2GHz when the sample thickness is 6.8mm, and the paraffin is used as a substrate.

Example 5:

the procedure of example 1 was followed, except that 1.2848g (0.054M) of CoCl was added simultaneously to the solution₂·6H₂O and 0.8557g (0.036M) NiCl₂·6H₂O, 5mL of anhydrous hydrazine hydrate. The morphology of the obtained product observed under a scanning electron microscope is shown in figure 14, the particle diameter is 0.91-1.95 mu m, and the wall thickness is 34-57 nm.

Example 6:

the procedure of example 1 was followed, except that 2.5696g (0.108M) of CoCl was added simultaneously to the solution₂·6H₂O and 1.7114g (0.072M) NiCl₂·6H₂O, 10mL of anhydrous hydrazine hydrate. The morphology of the obtained product observed under a scanning electron microscope is shown in figure 15, the particle diameter is 1.88-3.35 mu m, and the wall thickness is 30-50 nm.

Example 7:

the procedure of example 1 was followed, except that 0.6g (6g/L) of PVP was added. The appearance of the obtained product observed under a scanning electron microscope is shown in figure 16, the particle diameter is 1.19-1.66 mu m, and the wall thickness is 60-110 nm.

Example 8:

the procedure of example 1 was followed, except that the reaction time was 3 hours under reflux. The appearance of the obtained product observed under a scanning electron microscope is shown in figure 17, the particle diameter is 1.03-2.03 mu m, and the wall thickness is 60-170 nm.

Example 9:

the steps are the same as those of the example 1, 98mL of glycerol and 4.5mL of deionized water are added as solvents, the morphology of the obtained product observed under a scanning electron microscope is shown in FIG. 18, the particle diameter is 0.86-1.65 μm, and the wall thickness is 56-162 nm.

Example 10:

the procedure of example 1 was followed, except that the reaction temperature was 170 ℃ under reflux. The morphology and the element composition of the obtained product observed under a scanning electron microscope are respectively shown in FIGS. 19 and 20, the particle diameter is 0.32-0.68 mu m, and the wall thickness is 41-106 nm.

Example 11:

the procedure of example 1 was followed, except that the reaction temperature was 180 ℃ under reflux. The appearance of the obtained product observed under a scanning electron microscope is shown in figure 21, the particle diameter is 0.94-2 mu m, and the wall thickness is 210-370 nm.

Example 12:

0.6725g (0.027M) of C were added simultaneously to the solution in the same procedure as in example 1₄H₆CoO₄·4H₂O and 0.4279g (0.018M) C₄H₆NiO₄·4H₂And O. The morphology of the obtained product observed under a scanning electron microscope is shown in figure 22, the particle diameter is 0.96-1.66 mu m, and the wall thickness is 48-91 nm.

Example 13:

1.2g (12g/L) of a surfactant, polyvinylpyrrolidone PVP, was dissolved in a solution of 98mL of ethylene glycol and 4.5mL of deionized water and stirred well, and 0.6424g (0.027M) of CoCl was added to the solution simultaneously₂·6H₂O and 0.4279g (0.018M) NiCl₂·6H₂Stirring with O electric motor for 2h, adding 5mL anhydrous hydrazine hydrate dropwise into the solution, stirring for one hour, heating the mixture to 197 deg.C, condensing and refluxing for 4 hours, cooling, and adding ethanol for several timesMagnetic separation and washing are carried out until the solution is clear, and finally, the required magnetic alloy hollow microspheres are obtained after drying. The morphology of the obtained product observed under a scanning electron microscope is shown in figure 23, the particle diameter is 1.22-2.18 mu m, and the wall thickness is 110-180 nm

Example 14:

1.2g (12g/L) of a surfactant, polyvinylpyrrolidone PVP, was dissolved in a solution of 98mL of ethylene glycol and 4.5mL of deionized water and stirred well, and 0.6424g (0.027M) of CoCl was added to the solution simultaneously₂·6H₂O and 0.4279g (0.018M) NiCl₂·6H₂And (3) stirring for 2 hours under an electric power, then dropwise adding 12.5mL of anhydrous hydrazine hydrate into the solution, stirring for one hour, heating the mixture to boil at 197 ℃, condensing and refluxing for 4 hours, cooling, then carrying out magnetic separation and washing for multiple times by using ethanol until the solution is clear, and finally drying to obtain the required magnetic alloy hollow microspheres. The morphology of the obtained product observed under a scanning electron microscope is shown in figure 24, and the particle diameter is 1.14-2.32 μm.

Example 15:

the procedure of example 1 was followed except that the solvent composition was 99mL of ethylene glycol and 3.5mL of deionized water. The morphology and the element composition of the obtained product observed under a scanning electron microscope are respectively shown in FIG. 25, the particle diameter is 0.86-1.87 mu m, and the wall thickness is 72-148 nm.

Example 16:

the procedure of example 1 was followed, except that the solvent composition was 96mL of ethylene glycol and 6.5mL of deionized water. The morphology and the element composition of the obtained product observed under a scanning electron microscope are respectively shown in FIG. 26, the particle diameter is 0.81-1.25 μm, and the wall thickness is 34-56 nm.

Claims

1. A preparation method of magnetic alloy hollow microspheres is characterized by adopting a mixed solvent high-temperature liquid phase reduction method, and specifically comprises the following steps: metal salt, a surfactant, a reducing agent, an organic solvent and water are proportioned according to a certain stoichiometric ratio, the organic solvent, the water and the surfactant are added into a three-neck flask according to a certain proportion, and the mixture is stirred for 10 minutes; then adding metal salt and stirring for 2 hours, then dropping a reducing agent and stirring for 1 hour, then condensing and refluxing for 3-4 hours at the temperature of 170-197 ℃, cooling, then carrying out magnetic separation and washing for multiple times by using ethanol, and finally drying to obtain the required magnetic alloy hollow microspheres; the organic solvent is glycol or glycerol; the surfactant is polyvinylpyrrolidone;

the dosage of each raw material is as follows: the concentration of the metal salt is 0.045-0.18 mol/L, the mass fraction of the surfactant is 6-12 g/L, the ratio of the volume of the reducing agent to the total mass of the metal salt is 0.556-2.778 ml/mmol, and the volume ratio of the deionized water to the organic solvent is 3.5:99-6.5: 96;

the effective components of the microsphere are Co and Ni, and the structural formula of the microsphere is Co_xNi_1-xWherein: x is more than or equal to 0.14 and less than or equal to 1; the hollow structure has the diameter of 0.32-3.35 mu m and the wall thickness of 4-370 nm; the saturation magnetization of the magnetic material is 80.4-152.89 emu^.g^-1。

2. The method for preparing hollow microspheres of magnetic alloy according to claim 1, wherein the reducing agent is anhydrous hydrazine hydrate or 50-85% hydrazine hydrate by volume.

3. The method for preparing hollow microspheres of magnetic alloy as claimed in claim 1, wherein the metal salt is one of chloride and acetate of cobalt and nickel.

4. The method for preparing hollow microspheres of magnetic alloy according to claim 1, wherein the ratio of the amount of cobalt salt to nickel salt is 1 (0-4).

5. The method of claim 1, wherein the magnetic alloy hollow microsphere is formed by etching with water and Oswald ripening mechanism.