WO2020111384A1 - Magnetic nanostructures comprising copper and preparation method of same - Google Patents

Abstract

Provided is a preparation method of magnetic nanostructures. The preparation method of magnetic nanostructures may comprise the steps of: preparing a source solution comprising a first precursor comprising a rare earth element, a second precursor comprising a transition metal element, and a third precursor comprising Cu; electrospinning the source solution to form preliminary magnetic nanostructures comprising a rare earth element oxide, a transition metal oxide, and a Cu oxide; and reducing the preliminary magnetic nanostructures to produce magnetic nanostructures comprising an alloy composition comprising the rare earth element, the transition metal element, and the Cu.

Description

Magnetic nanostructure containing copper and method for manufacturing the same

The present invention relates to a magnetic nanostructure containing copper and a method for manufacturing the same, and relates to a magnetic nanostructure containing copper and a method of manufacturing the same from a source solution containing a rare earth element.

Hard magnetic permanent magnets have been indispensable for electric devices such as motors, speakers, measuring instruments, and small motors in hybrid vehicles (HEV) and electric vehicles (EV). R ₂ Fe ₁₄ B series, R ₂ Fe ₁₇ N _x series and R ₂ TM ₁₇ series (R: rare earth elements, TM: transition metal elements) are widely used as these magnet materials. Unlike, R ₂ TM ₁₇ system is not easily thermally decomposed and has a high Curie temperature, which has advantages in terms of phase formation and chemical stability.

In recent years, in keeping with the light weight, miniaturization, and high performance of electronic products, a permanent magnet material having an improved maximum magnetic energy ((BH)max) is required. However, since each material has a critical point of magnetic properties, studies are being conducted to overcome this.

For example, in the Republic of Korea Patent Publication No. 10-2017-0108468 (application number: 10-2016-0032417, applicant: Yonsei University Industry-University Cooperation Foundation), a substrate, and formed on the substrate, a Bi thin film layer and a Mn thin film layer laminated Disclosed is a non-rare permanent magnet with improved coercive force including a thin film laminate obtained by repeatedly laminating and heat-treating units at least twice or more and a method for manufacturing the same.

One technical problem to be solved by the present invention is to provide a magnetic nanostructure including copper (Cu) with improved magnetic properties and a method for manufacturing the same.

Another technical problem to be solved by the present invention is to provide a magnetic nanostructure including copper (Cu) and a method of manufacturing the same, which can improve magnetic properties by a simple process.

Another technical problem to be solved by the present invention is to provide a magnetic nanostructure including copper (Cu) and a method for manufacturing the same, which have reduced economic cost.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above-described technical problems, the present invention provides a method for manufacturing a magnetic nano structure.

According to one embodiment, the method of manufacturing the magnetic nanostructure comprises preparing a source solution including a first precursor containing a rare earth element, a second precursor containing a transition metal element, and a third precursor containing Cu. , Electrospinning the source solution to form a preliminary magnetic nanostructure including a rare earth oxide, a transition metal oxide, and Cu oxide, and reducing the preliminary magnetic wire to reduce the rare earth element, the transition metal element, and It may include the step of manufacturing a magnetic nano-structure comprising the alloy composition of the Cu.

According to one embodiment, the molar ratio of the Cu in the source solution may include more than 5.8 at% and less than 10.0 at%.

According to an embodiment, the forming of the magnetic nanostructure may include mixing the preliminary magnetic nanostructure with a reducing agent, heat treating the preliminary magnetic nanostructure mixed with the reducing agent, and heat-treated the preliminary magnetic nanostructure. , Washing with a washing solution.

According to one embodiment, the reducing agent may include calcium (Ca).

According to an embodiment, the method of manufacturing a magnetic nanostructure may include controlling a content of the Cu to control a coercive force.

In order to solve the above technical problems, the present invention provides a magnetic nano structure.

According to an embodiment, the magnetic nanostructure includes an alloy composition of rare earth elements, transition metal elements, and Cu, and in the alloy composition, the content of Cu is greater than 5.8 wt% and less than 10.0 wt% Can be.

According to one embodiment, the alloy composition, ReM ₅ (Re: rare earth element, M: at least one of transition metal elements or Cu) may be composed of a unit lattice (unit cell).

According to an embodiment, the crystal structure of ReM ₅ may include a hexagonal system.

According to an embodiment, the Cu may include being disposed at at least one of 2c and 2g sites in the unit grid.

According to one embodiment, the rare earth element may include any one of La, Ce, Pr, Nd, Sm, or Gd.

According to an embodiment, the transition metal element may include either Co or Ni.

According to one embodiment, the magnetic nanostructure, may have a single crystal (single crystal), and anisotropic (anisotropic) properties.

According to an embodiment, in the alloy composition, the content of the rare earth element is 16.7 wt%, and the content of the transition metal element may include more than 73.3 wt% and less than 77.5 wt%.

According to another embodiment, the magnetic nanostructure may include an alloy composition composed of a unit lattice represented by <Formula 1> below.

<Formula 1>

ReTM _x Cu _5-x

(Re: rare earth element, TM: transition metal element)

According to another embodiment, the magnetic nanostructure, in the alloy composition composed of a unit lattice represented by <Formula 2> below, more than 7% and less than 12% of the TM is substituted with the Cu, the <Formula 1 It may include an alloy composition having a unit grid represented by >.

<Formula 2>

ReTM ₅

(Re: rare earth element, TM: transition metal element)

According to another embodiment, the magnetic nanostructure may have a coercive force of 40000 Oe or more.

Method of manufacturing a magnetic nanostructure according to an embodiment of the present invention, to prepare a source solution comprising a first precursor containing a rare earth element, a second precursor containing a transition metal element, and a third precursor containing Cu Step, electrospinning the source solution to form a preliminary magnetic nanostructure including rare earth oxide, transition metal oxide, and Cu oxide, and reducing the preliminary magnetic nanostructure to reduce the rare earth element and the transition metal element. And, It may include the step of manufacturing a magnetic nano-structure comprising the alloy composition of the Cu. That is, the method of manufacturing the magnetic nanostructure according to the embodiment may have a bottom-up approach.

When a magnetic nanostructure is manufactured through a manufacturing method having such a bottom-up feature, as a simple method of controlling the content of the third precursor in the source solution preparation step, the Cu content in the magnetic nanostructure that is the final product may be controlled. Can be. Cu content in the magnetic nanostructure is greater than 5.8 wt% and less than 10.0 wt%, or the magnetic nanostructure is more than 7% and 12% of the TM in the alloy composition consisting of a unit lattice represented by <Formula 2> When less than is substituted with Cu, and having a unit lattice represented by <Formula 1>, the coercive force of the magnetic nanostructure may be improved. As a result, a magnetic nanostructure with improved magnetic properties can be provided. In addition, as copper is used as a substitute for expensive cobalt, a magnetic nanostructure with reduced economic cost can be provided.

1 is a flowchart illustrating a method of manufacturing a magnetic nano structure according to an embodiment of the present invention.

2 is a flow chart specifically explaining a step of forming a magnetic nanostructure in a method of manufacturing a magnetic nanostructure according to an embodiment of the present invention.

3 is a view showing a manufacturing process of a magnetic nanostructure according to an embodiment of the present invention.

4 is a view showing a unit grid represented by SmCo ₅ to describe the structure of a magnetic nanostructure according to an embodiment of the present invention.

5 to 9 are photographs of magnetic nanostructures according to embodiments and comparative examples 1 of the present invention.

10 is a graph showing X-ray diffraction analysis of the Sm-Co alloy composition and the Sm-Co-Cu alloy composition.

11 is a graph showing X-ray diffraction analysis of the magnetic nanostructures according to Examples and Comparative Examples 1 of the present invention.

12 and 13 are X-ray diffraction analysis graphs for analyzing the structure of the magnetic nanostructures according to Examples and Comparative Examples 1 of the present invention.

14 is a graph showing magnetization characteristics of a magnetic nanostructure according to embodiments and comparative examples of the present invention.

15 is a graph comparing the coercive force of a magnetic nanostructure according to embodiments and comparative examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete and that the spirit of the present invention is sufficiently conveyed to those skilled in the art.

In the present specification, when a component is referred to as being on another component, it means that it may be formed directly on another component, or a third component may be interposed between them. In addition, in the drawings, the thickness of the films and regions are exaggerated for effective description of the technical content.

In addition, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another component. Therefore, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, in this specification,'and/or' is used to mean including at least one of the components listed before and after.

In the specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. Also, terms such as “include” or “have” are intended to indicate the presence of features, numbers, steps, elements, or combinations thereof described in the specification, and one or more other features, numbers, steps, or configurations. It should not be understood as excluding the possibility of the presence or addition of elements or combinations thereof. In addition, in the present specification, “connecting” is used in a sense to include both indirectly connecting a plurality of components, and directly connecting.

In addition, in the following description of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

1 is a flowchart illustrating a method of manufacturing a magnetic nanostructure according to an embodiment of the present invention, and FIG. 2 is a detailed description of a step of forming a magnetic nanostructure among methods of manufacturing a magnetic nanostructure according to an embodiment of the present invention Flowchart, Figure 3 is a view showing a manufacturing process of a magnetic nanostructure according to an embodiment of the present invention, Figure 4 is a unit grid represented by SmCo ₅ to describe the structure of the magnetic nanostructure according to an embodiment of the present invention It is a figure showing.

1 to 3, a source solution including a first precursor, a second precursor, and a third precursor may be prepared (S100). According to an embodiment, the first precursor may include a rare-earth element. For example, the rare earth element may include any one of La, Ce, Pr, Nd, Sm, or Gd. According to one embodiment, the second precursor may include a transition-metal element. For example, the transition metal element may include either Co or Ni. According to one embodiment, the third precursor may include Cu.

The source solution may further include a viscous source. According to one embodiment, the viscous source may include a polymer. For example, the polymer may include at least one of polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), poly(vinyl acetate) (PVAC), polyvinylbutyral (PVB), poly(vinyl alcohol) (PVA), or polyethylene oxide (PEO). It can contain. The viscous source may give viscosity to the source solution, thereby controlling the diameter of the magnetic nanostructure described below.

According to one embodiment, the molar fraction (at %) of the third precursor in the source solution may be controlled. Specifically, the molar ratio of the Cu in the source solution may be controlled to be greater than 5.8 at% and less than 10.0 at%. In this case, in the magnetic nanostructure described below, in the alloy composition composed of the unit lattice represented by <Formula 2> below, more than 7% and less than 12% of the TM are substituted with the Cu, to the <Formula 1> It may have a unit grid displayed. Accordingly, the maximum magnetic energy index ((BH) _max ) of the magnetic nanostructure may be improved. More detailed description will be given later.

<Formula 1>

ReTM _x Cu _5-x

(Re: rare earth element, TM: transition metal element)

<Formula 2>

ReTM ₅

(Re: rare earth element, TM: transition metal element)

The source solution may be electrospinned to form a preliminary magnetic nanostructure (S200). The preliminary magnetic nanostructure formed by electrospinning the source solution may include rare earth oxide, transition metal oxide, and Cu oxide.

According to one embodiment, the preliminary hybrid magnetic fiber forming step may include a first preliminary hybrid magnetic fiber forming step, and a second preliminary hybrid magnetic fiber forming step. The first preliminary hybrid magnetic fiber forming step may be performed by a method of electrospinning the source solution. The first preliminary hybrid magnetic fiber may be formed of a solid component of the source solution. The first preliminary hybrid magnetic fiber may include a water-soluble metal salt, a polymer, and the like. The step of forming the second preliminary hybrid magnetic fiber may be performed by a method of calcining the first preliminary hybrid magnetic fiber. That is, the first preliminary hybrid magnetic fiber may be heat-treated to decompose an organic material including a polymer in the first preliminary hybrid magnetic fiber. The second preliminary hybrid magnetic fiber may include rare earth oxide, transition metal oxide, and Cu oxide.

More specifically, the source solution may be injected into a syringe (10), and the source solution may be radiated using a syringe pump (20). In this case, the tip 30 of the syringe has a diameter of 0.05 to 2 mm, the syringe tip 30 and the pre-hybrid magnetic fiber collector (collector 40) are spaced 10-20 cm apart, and the syringe pump ( 20) is capable of spinning the source solution at a rate of 0.3 to 0.8 mL/h. In addition, the voltage applied for electric radiation may be 16 to 23 kV. The first preliminary hybrid magnetic fiber may be formed through the above-described process.

The first preliminary hybrid magnetic fiber may be collected in an alumina crucible and heat-treated in an atmospheric pressure of 500 to 900°C in an atmospheric atmosphere. In this process, all organic substances including polymers can be thermally decomposed. At this time, the temperature increase rate condition may be 1 to 10°C per minute. The second preliminary hybrid magnetic fiber may be formed through the above-described process.

The preliminary magnetic nanostructure may be reduced to form a magnetic nanostructure (S300). The magnetic nanostructure may include a rare earth element, a transition metal element, and an alloy composition of Cu. In addition, the magnetic nanostructure may be an alloy composition composed of a unit lattice represented by <Formula 1> below. More specifically, the magnetic nanostructure may include 15 to 18 wt% of the rare earth element, 70 to 79 wt% of the transition metal element, and 5.5 to 10.5 wt% of Cu. In addition, as the magnetic nanostructure is formed by an electrospinning method as described above, it may have a wire shape or a fiber shape.

<Formula 1>

ReTM _x Cu _5-x (Re: rare earth element, TM: transition metal element)

According to one embodiment, the magnetic nanostructure, may have a crystal structure (crystal structure). For example, the magnetic nanostructure may have a single crystal. When the magnetic nanostructure has a crystal structure, the magnetic nanostructure may be composed of a unit cell represented by ReM ₅ (at least one of Re: rare earth element, M: transition metal element, or Cu). . The crystal structure of ReM ₅ may be hexagonal.

The arrangement of atoms in the unit lattice represented by ReM ₅ may be the same as the arrangement of atoms in the unit lattice represented by SmCo ₅ . That is, the arrangement of Re (rare earth elements) in the unit lattice represented by ReM ₅ may be the same as the arrangement of Sm in the unit lattice represented by SmCo ₅ . In addition, the arrangement of M (at least one of transition metal elements or Cu) in the unit lattice represented by ReM ₅ may be the same as the arrangement of Co in the unit lattice represented by SmCo ₅ .

For more specific description, referring to FIG. 4, a unit grid represented by SmCo ₅ is shown. As illustrated in FIG. 4, in the unit grid represented by SmCo ₅ , Co may be disposed at at least one of 2c and 2g sites. Accordingly, in the unit grid represented by ReM ₅ , M may also be disposed at at least one of 2c and 2g sites. That is, the transition metal element or Cu may be disposed at 2c and 2g sites of the unit lattice represented by ReM ₅ .

In the magnetic nanostructure according to the embodiment, as the content of Cu increases, the saturation magnetization value and the residual magnetization value decrease, and squareness and coercive force improve. Can be. However, the ratio of the improved squareness ratio and the coercive force may be larger than the ratio of the reduced saturation magnetization value and the residual magnetization value. Accordingly, when the Cu content is increased, the maximum magnetic energy value ((BH) _max ) expressed as a product of the saturation magnetization value and the coercive force may be improved.

However, when the content of Cu exceeds a predetermined criterion, a problem in that the coercive force is significantly reduced may occur. More specifically, when the content of Cu exceeds a predetermined criterion, the energy level of the Cu is smaller as the atomic radius of Cu (1.57 Å) is smaller than the atomic radius of the transition metal (for example, 1.67 Å for Co). A stable SmCu ₅ phase can be easily formed. Accordingly, the magnetic nanostructure according to the embodiment may represent a composite phase form of ReM ₅ and ReCu ₅ , rather than the form of the single phase ReM ₅ described above. In the case of the ReM ₅ single phase, it exhibits anisotropy and exhibits high coercive force, but when a plurality of phases are mixed, it exhibits isotropy and exhibits low coercive force.

As a result, in order to obtain a high maximum magnetic energy value, the Cu content in the magnetic nanostructure according to the embodiment may be controlled. According to one embodiment, the Cu content in the magnetic nanostructure may be controlled to more than 5.8 wt% and less than 10.0 wt%. In addition, in the magnetic nanostructure, in the alloy composition composed of the unit lattice represented by <Formula 2> below, more than 7% and less than 12% of TM are substituted with Cu, and the unit represented by <Formula 1> And alloy compositions having a lattice.

<Formula 2>

ReTM ₅

(Re: rare earth element, TM: transition metal element)

That is, in the magnetic nanostructure, when the amount of substitution of the Cu substituting the TM is controlled to be more than 7% and less than 12%, the Cu content in the magnetic nanostructure may be greater than 5.8 wt% and less than 10.0 wt. As described above, when the content of Cu is controlled, the magnetic nanostructure may exhibit a ReM ₅ single phase and a high coercive force of 40000 Oe or more.

Unlike the above, when the Cu substitution amount in the magnetic structure is 7% or less, or 12% or more, a problem in that the coercive force and the maximum magnetic energy value may be reduced. In particular, when the amount of Cu substitution in the magnetic structure is less than 5%, the magnetic structure may exhibit a structure in which the Re ₂ M ₁₇ phase, the Re ₂ M ₇ phase, and the ReM ₅ phase are mixed, thereby lowering the coercive force. In addition, when the amount of Cu substitution in the magnetic structure is 20% or more, the magnetic structure may exhibit a structure in which the ReM ₅ phase and the ReCu ₅ phase are mixed, resulting in a problem that the coercive force is lowered.

According to an embodiment, as the Cu content in the magnetic nanostructure increases, the size of the crystal included in the magnetic nanostructure may increase. That is, as the Cu content in the magnetic nanostructure increases, crystallinity of the magnetic nanostructure may be improved. As a result, the Cu may affect the crystallinity of the magnetic nanostructure.

According to one embodiment, the forming of the magnetic nanostructure (S300) comprises mixing the preliminary magnetic nanostructure with a reducing agent (S310), and heat-treating the preliminary magnetic nanostructure mixed with the reducing agent (S320), And washing the pre-treated magnetic nanostructures with a washing solution (S330). That is, after the preliminary magnetic nanostructure is mixed with a reducing agent, and then heat-treated, the magnetic nanostructure may be formed.

The reducing agent may include calcium (Ca). For example, the reducing agent may include CaH ₂ . In this case, the magnetic nanostructure can be easily formed. Specifically, in the case of rare earth elements, it has very small oxidation energy, so it can maintain the most stable phase in the form of oxide. Accordingly, in order to reduce the rare earth oxide to a metal, a high temperature and a hydrogen atmosphere of 1500° C. or higher are required, resulting in process difficulties. However, since calcium (Ca) has a smaller oxidation energy than rare earth elements, when it is used as a reducing agent, a relatively low heat treatment temperature (for example, 500 to 800°C) and a rare earth oxide metal in a non-hydrogen atmosphere Can be easily reduced.

The washing solution may include at least one of ammonium chloride (NH ₄ Cl), and methanol (CH ₃ OH). In this case, the magnetic nanostructure can be easily formed. Specifically, when the preliminary magnetic nanostructure is reduced using a reducing agent containing calcium (Ca), calcium oxide (CaO) may be formed on the surface of the metal on which the rare earth oxide is reduced. Accordingly, a process for removing calcium oxide (CaO) is required. In the existing calcium oxide (CaO) removal process, a washing solution in which acetic acid or hydrochloric acid is mixed with ultrapure water was used. In this case, a problem may occur when the acid solution generates a fatal effect such as corrosion and oxidation even in the magnetic phase. However, in the case of a washing solution containing at least one of ammonium chloride (NH ₄ Cl) and methanol (CH ₃ OH), calcium oxide (CaO) can be easily removed without affecting the magnetic phase. .

Conventional methods for producing rare earth permanent magnets are composed of powder metallurgy methods such as melt casting of ingots, extrusion molding or injection molding, and they have a feature of a top-dowm approach. When a substitution type alloy is manufactured through a top-down approach, it is easy to form a complex microstructure of a grain-grain boundary rather than a single crystal form, and an isotropic alloy can be obtained while numerous grains are generated. . As a result, such an isotropic alloy may lower the coercive force and cause deterioration of magnetic properties. In addition, since defects and impurities are easily generated in the grain boundaries, and the grains and grain boundaries are easily formed in different phases, magnetic properties are exhibited by showing the behavior of the binary-phase separated on the magnetic hysteresis curve. A problem that adversely affects may occur.

However, the method of manufacturing a magnetic nanostructure according to an embodiment of the present invention includes a source solution including a first precursor containing a rare earth element, a second precursor containing a transition metal element, and a third precursor containing Cu. Preparing, electrospinning the source solution, forming a pre-magnetic nanostructure including rare earth oxide, transition metal oxide, and Cu oxide, and reducing the pre-magnetic nanostructure to reduce the rare earth element and the transition. It may include the step of preparing a magnetic nanostructure comprising a metal element, and the alloy composition of the Cu. That is, the method of manufacturing the magnetic nanostructure according to the embodiment may have a bottom-up approach.

When a magnetic nanostructure is manufactured through a manufacturing method having such a bottom-up feature, as a simple method of controlling the content of the third precursor in the source solution preparation step, the Cu content in the magnetic nanostructure that is the final product may be controlled. Can be. As described above, the Cu content in the magnetic nanostructure is controlled to be greater than 5.8 wt% and less than 10.0 wt%, or the magnetic nanostructure is 7% of the TM in an alloy composition composed of a unit lattice represented by <Formula 2> When the excess and less than 12% are substituted with the Cu, and having a unit lattice represented by <Formula 1>, the coercive force of the magnetic nanostructure may be improved. As a result, a magnetic nanostructure with improved magnetic properties can be provided. In addition, as copper is used as a substitute for expensive cobalt, a magnetic nanostructure with reduced economic cost can be provided.

As described above, a magnetic nano structure according to an embodiment of the present invention and a manufacturing method thereof have been described. Hereinafter, specific experimental examples and property evaluation results of the magnetic nanostructures and methods for manufacturing the same according to the embodiment of the present invention will be described.

Preparation of magnetic nanostructures according to Example 1

Samarium(III) nitrate hexahydrate; Sm(NO ₃ ) ₃ 6H ₂ O), Cobalt(II) nitrate hexahydrate; Co(NO ₃₎ ) ₂ 6H ₂ O), copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O), and PVP at a concentration of 3 wt% were mixed to prepare a source solution.

The prepared source solution is placed in a syringe for electrospinning and the solution is continuously pushed at a rate of 0.8 mL/h using a syringe pump. At this time, the tip portion of the syringe and the collector where the spun fibers are collected are spaced apart at 15 cm intervals, and a high voltage of 16 kV is applied to radiate the source solution by a potential difference. The material deposited on the collector is collected in an alumina (Al ₂ O ₃ ) crucible and calcined in an atmosphere at a temperature of about 700° C. for 3 hours to decompose all organic substances including polymers.

The calcined material is mixed with CaH ₂ in a volume ratio of 1:1 and reduced by heat treatment for about 1 hour at a temperature of about 700° C. in an inert atmosphere, followed by washing with a mixed solution of ammonium chloride and methanol, resulting in Cu compared to Co. A magnetic nanostructure according to the first embodiment substituted with 3% was prepared.

Preparation of magnetic nanostructures according to Example 2

A magnetic nanostructure was prepared by the method according to Example 1, but the ratio of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution was controlled, so that Cu compared to Co was substituted by 5%. Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Example 3

A magnetic nanostructure was prepared by the method according to Example 1, but the third embodiment in which Cu was 7% substituted with Co by controlling the ratio of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Example 4

A magnetic nanostructure was prepared by the method according to Example 1, but the fourth embodiment in which Cu was 10% substituted with Co by controlling the ratio of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Example 5

A magnetic nanostructure was prepared by the method according to Example 1, but by controlling the ratio of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution, the fifth implementation in which Cu was 12% substituted compared to Co Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Example 6

A sixth embodiment in which Cu is 15% substituted with Co by controlling the proportion of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution, by preparing a magnetic nanostructure in the method according to Example 1 above. Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Example 7

A magnetic nanostructure was prepared by the method according to Example 1, but by controlling the ratio of copper nitrate trihydrate (Cu(NO ₃ ) ₂ 3H ₂ O) in the source solution, the seventh embodiment in which Cu was substituted by 20% compared to Co Magnetic nanostructures according to examples were prepared.

Preparation of magnetic nanostructures according to Comparative Example 1

Samarium(III) nitrate hexahydrate; Sm(NO ₃ ) ₃ 6H ₂ O), cobalt(II) nitrate hexahydrate; Co(NO ₃ ) ₂ 6H in ultrapure water ₂ O), and PVP are mixed to prepare a source solution.

The prepared source solution was reduced after spinning by the method according to Example 1 to prepare a magnetic nanostructure according to a comparative example not containing Cu.

The magnetic nanostructures according to the examples and comparative examples are summarized through <Table 1> below, and specific component ratios of the magnetic nanostructures according to the examples and comparative examples are summarized through <Table 2> below.

division	Configuration	Cu substitution amount compared to Co
Example 1	Sm-Co-Cu	3%
Example 2	Sm-Co-Cu	5%
Example 3	Sm-Co-Cu	7%
Example 4	Sm-Co-Cu	10%
Example 5	Sm-Co-Cu	12%
Example 6	Sm-Co-Cu	15%
Example 7	Sm-Co-Cu	20%
Comparative Example 1	Sm-Co	0 %

division	Sm	Co	Cu
Example 1	16.7 wt%	80.8 wt%	2.5 wt%
Example 2	16.7 wt%	79.2 wt%	4.2 wt%
Example 3	16.7 wt%	77.5 wt%	5.8 wt%
Example 4	16.7 wt%	75.0 wt%	8.3 wt%
Example 5	16.7 wt%	73.3 wt%	10.0 wt%
Example 6	16.7 wt%	70.8 wt%	12.5 wt%
Example 7	16.7 wt%	66.7 wt%	16.7 wt%
Comparative Example 1	16.7 wt%	83.3 wt%	0 wt%

5 to 9 are photographs of magnetic nanostructures according to embodiments and comparative examples 1 of the present invention.

5 to 9, the magnetic nanostructures according to Comparative Example 1, Example 2, Example 4, Example 6, and Example 7 were respectively photographed by scanning electron microscope (SEM), and FIGS. 5 to 9. It was shown in. In addition, during each of the manufacturing process of the magnetic nanostructure, the state immediately after electrospinning, the sintered state, and the reduced state, respectively, were photographed and shown in (a) to (c).

5 to 9, the magnetic nanostructures according to Comparative Examples 1, 2, 4, 6, and 7 undergo electrospinning, sintering, and reduction processes. It was confirmed that the crystal form was exhibited. In addition, seeing that the size of the crystals included in each magnetic nanostructure gradually increases in the order of Comparative Example 1, Example 2, Example 4, Example 6, and Example 7, the crystal grains as the content of Cu increases It was found that the size increased. The grain size included in each magnetic nanostructure is summarized through <Table 3> below, and the size of grains was calculated through <Equation 1> below.

division	Grain size
Comparative Example 1	22.41 nm
Example 2	26.10 nm
Example 4	28.95 nm
Example 6	31.61 nm
Example 7	36.56 nm

<Equation 1>

(D: grain size, k: shape constant (=0.9), λ: 0.1541 nm, β: FWHM (deg.), θ: peak angle (deg.))

10 is a graph showing X-ray diffraction analysis of the Sm-Co alloy composition and the Sm-Co-Cu alloy composition.

Referring to FIG. 10, X-ray diffraction diffraction patterns were shown for each of the SmCo ₅ alloy composition, SmCo _4.5 Cu _0.5 alloy composition, SmCo ₄ Cu alloy composition, SmCo _3.5 Cu _1.5 alloy composition, and SmCo ₂ Cu ₃ alloy composition. .

As can be seen in FIG. 10, in the case of the alloy composition containing Cu, it was confirmed that the pattern was shifted at a low angle compared to the SmCo ₅ alloy composition. In addition, even in the Sm-Co-Cu alloy composition, as the content of Cu increased, it was confirmed that the pattern was shifted at a low angle. This has the same arrangement of atoms in the unit lattice represented by Sm _x Co _y (x,y>0) and atoms in the unit lattice represented by Sm _x Co _y Cu _z (x,y,z>0). However, it can be determined that this is a phenomenon that occurs as Cu is disposed in the place of Co. More specifically, when Cu is disposed at the position of Co in the unit lattice represented by Sm _x Co _y , the energy level of Cu is smaller as the atomic radius of Cu (1.57 Å) is smaller than the atomic radius of Co (1.67 Å). It is easy to form a stable SmCu ₅ phase, which has a larger lattice constant than the SmCo ₅ phase, and thus exhibits a shift from the X-ray diffraction diffraction pattern to a low angle.

11 is a graph showing X-ray diffraction analysis of the magnetic nanostructures according to Examples and Comparative Examples 1 of the present invention.

Referring to FIG. 11, X-ray diffraction diffraction patterns are shown for each of the magnetic nanostructures according to Comparative Example 1, Example 2, Example 4, Example 6, and Example 7.

As can be seen through Figure 11, compared to the magnetic nanostructure according to Comparative Example 1 does not contain Cu, the magnetic according to Example 2, Example 4, Example 6, and Example 7 containing Cu In the nanostructure, it was confirmed that the pattern was shifted at a low angle. In addition, when the magnetic nanostructures according to Examples 2, 4, 6, and 7 were compared with each other, it was confirmed that the X-ray diffraction diffraction pattern shifted to a low angle as the Cu content increased. there was.

12 and 13 are X-ray diffraction analysis graphs for analyzing the structure of the magnetic nanostructures according to Examples and Comparative Examples 1 of the present invention.

12 and 13, X-ray diffraction analysis results of the magnetic nanostructures according to Example 7, Example 4, Example 2, Example 1, and Comparative Example are shown. 12(a) to 12(e) show the X-ray diffraction analysis results of the magnetic nanostructures according to Examples 7, Examples 4, 2, 1 and 1, respectively, and FIG. 13. (A) to (e) are graphs showing enlarged portions A to E shown in FIGS. 12A to 12E.

As can be seen in Figures 12 (d) and (e), 13 (d) and (e), the magnetic nanostructures according to Example 1 and Comparative Example 1, SmCo ₅ phase, Sm ₂ Co ₇ phase , And Sm ₂ Co ₁₇ phase was confirmed to indicate a mixed state.

Alternatively, as can be seen in FIGS. 12(b) and 12(c) and 13(b) and (c), the magnetic nanostructures according to Examples 2 and 4 above exhibited a single SmCo5 phase. I could confirm. In addition, as can be seen in FIGS. 12(a) and 13(a), it was confirmed that the magnetic nanostructures according to Example 7 exhibited a state in which the SmCo ₅ phase and the SmCu ₅ phase were mixed.

That is, in order to obtain a high coercive force through the anisotropic ReM ₅ single phase, it can be seen that in the magnetic nanostructure according to the embodiment, a minimum amount of substitution of the Cu relative to the transition metal is 5%.

14 is a graph showing magnetization characteristics of a magnetic nanostructure according to embodiments and comparative examples of the present invention.

Referring to FIG. 14, the saturation magnetization, squareness ratio, and coercive force of the magnetic nanostructures according to Comparative Example 1 and Examples 1 to 7 were measured and illustrated. The magnetic property values measured through FIG. 14 and the crystal phase structure of each magnetic nanostructure are summarized through <Table 4> below.

division	Crystalline structure (M: Co+Cu)	Saturation magnetization (emu/g)	Residual magnetization (emu/g)	Square ratio (%)	Coercive Force (Oe)
Comparative Example 1	Sm 2 Co 17 ,Sm 2 Co 7	75.716	45.063	59.516	7570.8
Example 1	SmM 5 Sm 2 M 17 ,Sm 2 M 7	65.416	43.310	66.207	13195.9
Example 2	SmM 5	55.927	39.074	69.867	29707.9
Example 3	SmM 5	54.365	41.078	75.559	35062.5
Example 4	SmM 5	51.652	39.433	76.276	40737.9
Example 5	SmM 5	50.774	37.840	74.525	37775.8
Example 6	SmM 5	48.888	36.972	75.626	18936.5
Example 7	SmM 5	45.267	34.132	75.403	16469.7

14 and <Table 4>, as compared with the magnetic nanostructures according to Comparative Example 1, it was confirmed that the saturation magnetization and residual magnetization of the magnetic nanostructures according to Examples 1 to 7 was low. On the other hand, compared with the magnetic nanostructures according to Comparative Example 1, it was confirmed that the coercive force of the magnetic nanostructures according to Examples 1 to 7 was high.

On the other hand, when the magnetic structures according to Examples 1 to 7 were compared with each other, it was confirmed that saturation magnetization and residual magnetization decreased as Cu content increased. In addition, it was confirmed that the magnetic structures according to Examples 1 to 4 increase the coercive force as the Cu content increases, while the magnetic structures according to Examples 5 to 7 decrease the coercive force as the Cu content increases.

As a result, when the substitution amount of Cu relative to Co is controlled to be more than 7% and less than 12%, saturation magnetization and residual magnetization are slightly reduced, but it can be seen that a magnetic nanostructure having improved magnetic properties is provided through remarkable coercive force improvement .

15 is a graph comparing the coercive force of a magnetic nanostructure according to embodiments and comparative examples of the present invention.

Referring to FIG. 15, magnetic nanostructures according to Examples 1 to 7 and magnetic nanostructures according to Comparative Examples 1 to 6 were prepared, and coercivity (H _ci , kOe) was measured for each, and shown. . The magnetic nanostructures according to Comparative Examples 2 to 6 are summarized through <Table 5> below.

division	Manufacturing method	rescue
Comparative Example 2	Induction melting, As-cast	SmCo 5-x Cu x alloys
Comparative Example 3	Induction melting, Annealed	SmCo 5-x Cu x alloys
Comparative Example 4	Arc-melting	Sm-Co-Cu and Pr-Co-Cu alloys in a ratio of 1:5
Comparative Example 5	Arc-melting	Sm(Co, Cu) 5 alloys
Comparative Example 6	Magnetron sputtering	SmCo 5

As can be seen in Figure 15, it was confirmed that the magnetic nanostructures according to the above embodiments exhibit a significantly higher coercive force than the magnetic nanoparticles according to the comparative examples. In addition, among the magnetic nanostructures according to the above embodiments, it was found that the coercive force of the magnetic nanostructures according to Example 4 was highest.

As described above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

The magnetic nanostructure including copper (Cu) according to an embodiment of the present invention may be used in various industrial fields such as a permanent magnet, an electric motor, and a sensor.

Claims (16)

1. Preparing a source solution comprising a first precursor comprising a rare earth element, a second precursor comprising a transition metal element, and a third precursor comprising Cu;

   Electrospinning the source solution to form a pre-magnetic nanostructure including rare earth oxide, transition metal oxide, and Cu oxide; And

   And reducing the preliminary magnetic wire to prepare a magnetic nanostructure including the rare earth element, the transition metal element, and the alloy composition of Cu.
2. According to claim 1,

   A method of manufacturing a magnetic nanostructure, wherein the molar ratio of Cu in the source solution is greater than 5.8 at% and less than 10.0 at%.
3. According to claim 1,

   The step of forming the magnetic nanostructure,

   Mixing the preliminary magnetic nanostructure with a reducing agent;

   Heat-treating the pre-magnetic nanostructure mixed with the reducing agent; And

   A method of manufacturing a magnetic nanostructure, comprising washing the pre-heated pre-magnetic nanostructure with a washing solution.
4. According to claim 1,

   The reducing agent, a method of manufacturing a magnetic nanostructure containing calcium (Ca).
5. According to claim 1,

   A method of manufacturing a magnetic nano structure, comprising controlling the content of the Cu to control a coercive force.
6. Rare earth elements, including transition metal elements, and alloy compositions of Cu,

   In the alloy composition, the magnetic content of the Cu is greater than 5.8 wt% and less than 10.0 wt%.
7. The method of claim 6,

   The alloy composition is a magnetic nano-structure consisting of a unit cell (Re cell) represented by ReM ₅ (Re: rare earth element, M: transition metal element or at least one of Cu).
8. The method of claim 7,

   The crystal structure of ReM ₅ is a magnetic nanostructure including a hexagonal system (hexagonal).
9. The method of claim 7,

   The Cu is a magnetic material that is disposed in at least one of 2c, 2g sites (site) in the unit lattice.
10. The method of claim 6,

    The rare earth element is a magnetic nanostructure comprising any one of La, Ce, Pr, Nd, Sm, or Gd.
11. The method of claim 6,

    The transition metal element is a magnetic nanostructure comprising either Co or Ni.
12. The method of claim 6,

    Magnetic nanostructures having single crystal and anisotropic properties.
13. The method of claim 6,

    In the alloy composition, the content of the rare earth element is 16.7 wt%, and the content of the transition metal element is greater than 73.3 wt% and less than 77.5 wt%.
14. Magnetic nanostructure comprising an alloy composition consisting of a unit grid represented by <Formula 1> below.

    <Formula 1>

    ReTM _x Cu _5-x

    (Re: rare earth element, TM: transition metal element)
15. The method of claim 14,

    In the alloy composition comprising the unit lattice represented by <Formula 2> below, more than 7% and less than 12% of the TM are substituted with the Cu to include the alloy composition having the unit lattice represented by <Formula 1> Magnetic nanostructures.

    <Formula 2>

    ReTM ₅

    (Re: rare earth element, TM: transition metal element)
16. The method of claim 14,

    Magnetic nano-structure having a coercive force of 40000 Oe or more.

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