KR102234488B1 - Hexagonal plate-shaped ferrite and method of fabricating of the same - Google Patents

Abstract

In the ferrite structure in the form of a hexagonal plate, it has a hexagonal magnetoplumbite-type crystal structure including a first metal and iron (Fe), and includes a hexagonal plate-shaped structure, wherein the crystal structure is A portion of the first metal may be substituted with a second metal, and the first metal may be included in a range of 0.35 or more and less than 0.70, and the second metal may be included in a range of more than 0 and less than 0.4.

Description

Hexagonal plate-shaped ferrite and method of fabricating of the same}

The present application relates to a hexagonal plate-shaped ferrite structure and a method of manufacturing the same, and more specifically, selectively including a magnetoplumite phase including a first metal and iron, wherein a part of the first metal is a second metal It relates to a ferrite structure in the form of a hexagonal plate substituted with and a manufacturing method thereof.

Hard magnetic permanent magnets have been used in electric devices such as motors, speakers, and measuring instruments, and motors such as hybrid vehicles and electric vehicles. As such a hard magnetic permanent magnet, a rare earth magnet having a large coercive force is mainly used.

Rare earth magnets have more than tens of times more magnetic properties than ferrite magnets, one of the non-rare earth magnets. However, due to the limited reserves of rare earth elements and high prices, research on gap magnets having magnetic properties as much as rare earth magnets is being conducted while reducing the amount of rare earth elements.

To develop a new gap magnet, use the exchange-coupling effect induced at the interface between the hard magnetic material and the soft magnetic material, find a new composition through first-principle calculation, or change the structure of a conventional commercial magnet. Research such as Let's is under way.

However, spring magnets manufactured using the exchange magnetic coupling effect have a nano-sized core-shell structure, and in most cases, the composition calculated as a result of the experiment is not implemented in the neomagnetic material manufactured through the first-principle calculation.

Therefore, a number of studies are currently underway to modify the composition of conventional commercial magnets to modify the microstructure. For example, Korean Patent Publication No. 10-2025520 (Application No. 10-2019-7009075) has a single crystal having an average particle diameter of 1 to 2000 nm, has a polyhedral particle shape, and contains 5 to 10% by weight of Ni, Ni-, characterized in that it contains 15 to 30% by weight of Zn, 1 to 5% by weight of Cu, and 25 to 50% by weight of Fe, characterized in that the Zn or the Cu is segregated on the surface. Zn-Cu-based ferrite particles are disclosed.

One technical problem to be solved by the present application is a ferrite in the form of a hexagonal plate with improved magnetic properties by selectively including a magnetoplumite phase including a first metal and iron, and a part of the first metal is replaced with a second metal. It is to provide a structure and a method of manufacturing the same.

Another technical problem to be solved by the present application is to provide a hexagonal plate-shaped ferrite structure having a high aspect ratio by inducing lateral growth through substitution, and a method of manufacturing the same.

Another technical problem to be solved by the present application is that it is oriented in an easy-axis for magnetization without a magnetic field applied from the outside, and has a hexagonal plate shape with improved intrinsic coercivity without deteriorating magnetization. It is to provide a ferrite structure and a method of manufacturing the same.

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

In order to solve the above technical problem, the present application provides a ferrite structure in the form of a hexagonal plate.

According to an embodiment, the ferrite structure has a hexagonal magnetoplumbyte type crystal structure including a first metal and iron (Fe), and includes a hexagonal plate shape, wherein the crystal structure is, A portion of the first metal may be substituted with a second metal, and the first metal may be included in a range of 0.35 or more and less than 0.70, and the second metal may be included in a range of more than 0 and less than 0.4. .

According to an embodiment, the ferrite structure may include one having an average aspect ratio in the range of 3.0 to 9.5.

According to an embodiment, the ferrite structure may include an increase in an average aspect ratio as the amount of the second metal increases.

According to an embodiment, when the second metal has a range of more than 0.15 and less than 0.25, the ferrite structure may include one having a maximum coercivity.

According to an embodiment, as the amount of the second metal increases, the ferrite structure may include an increase in a 2θ value representing the (107) plane in the X-ray diffraction pattern (XRD).

According to an embodiment, the ferrite structure may include an increase in the intensity of the (107) plane compared to the intensity of the (114) plane in the X-ray diffraction pattern (XRD) as the amount of the second metal increases. have.

According to an embodiment, the first metal may include strontium (Sr), and the second metal may include calcium (Ca).

According to an embodiment, the ferrite structure may include at least one of lanthanum (La) and cobalt (Co).

In order to solve the above technical problem, the present application provides a sintered magnet.

According to an embodiment, the sintered magnet may include the ferrite structure.

In order to solve the above technical problem, the present application provides a magnet for bonding.

According to an embodiment, the magnet for bonding may include the ferrite structure.

In order to solve the above technical problem, the present application provides a method of manufacturing a ferrite structure in the form of a hexagonal plate.

According to an embodiment, the method of manufacturing the ferrite structure includes preparing a precursor solution including a first metal precursor, a second metal precursor, an iron precursor, and a salt, and forming droplets by providing ultrasonic waves to the precursor solution. The step of pyrolyzing the droplet in an oxidizing atmosphere to form an intermediate oxide including a first metal, a second metal, and iron, and calcining the intermediate oxide in an oxidizing atmosphere, the first metal, the iron, And preparing a ferrite structure in the form of a hexagonal plate, which is an oxide containing oxygen and in which the second metal is substituted at the position of the first metal.

According to an embodiment, the pyrolyzing of the droplet may include performing at a first temperature, and the calcining of the intermediate oxide may include performing at a second temperature higher than the first temperature.

According to an embodiment, the step of pyrolyzing the droplet includes forming the intermediate oxide and simultaneously depositing the salt into crystals, and immediately after the step of preparing the ferrite structure, removing the crystal can do.

According to an embodiment, the precursor solution may include a third metal precursor and a fourth metal precursor.

According to an embodiment, the third metal precursor may include lanthanum nitrate, and the fourth metal precursor may include cobalt nitride.

A method of manufacturing a ferrite structure in a hexagonal plate shape according to an embodiment of the present invention includes preparing a precursor solution including a first metal precursor, a second metal precursor, an iron precursor, and a salt, and providing ultrasonic waves to the precursor solution. Forming a droplet by thermally decomposing the droplet in an oxidizing atmosphere to form an intermediate oxide including a first metal, a second metal, and iron, and calcining the intermediate oxide in an oxidizing atmosphere, the first metal, It is an oxide containing iron and oxygen, and may include manufacturing a ferrite structure in the form of a hexagonal plate in which the second metal is substituted at the position of the first metal.

The droplets are thermally decomposed, and the intermediate product is formed, and the salt may be crystallized. In this case, the salt may prevent aggregation of the metal precursors of the droplet, and the salt may be crystallized, and crystallinity of the intermediate product may be improved.

In the step of calcining the intermediate product, the intermediate product may be mainly crystallized in a transverse direction compared to a longitudinal direction, and the ferrite structure thus produced has a high aspect ratio (that is, the size of the particle diameter in the longitudinal direction relative to the length in the transverse direction) ) May have a hexagonal plate shape.

The ferrite structure may have an easy magnetization axis in the transverse direction, and the ferrite structure may be stacked along the easy magnetization axis substantially without an externally applied magnetic field. Accordingly, the ferrite structure having improved intrinsic coercivity can be manufactured without substantially lowering the magnetization.

1 is a flowchart illustrating a method of manufacturing a ferrite structure having a hexagonal plate shape according to an exemplary embodiment of the present invention.
2 to 3 are views for explaining a method of manufacturing a ferrite structure having a hexagonal plate shape according to an embodiment of the present invention.
4 is a schematic cross-sectional view of an ultrasonic spray pyrolysis apparatus (USP) for explaining a method of manufacturing a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.
5 is a schematic schematic diagram of a ferrite structure having a hexagonal plate shape according to an embodiment of the present invention.
6 is a scanning electron microscope (SEM) image immediately after a step of forming a droplet and a step of calcining an intermediate oxide in the manufacturing step of a ferrite structure having a hexagonal plate shape according to an embodiment of the present invention.
7 to 9 are scanning electron microscope (SEM) images of a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention in a shape according to the amount of substituted calcium.
10 is a scanning electron microscope (SEM) image of a stacked form of a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.
11 is a diagram illustrating particle distribution of the ferrite structure according to the amount of substituted calcium in the hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.
12 to 13 are diagrams illustrating an X-ray diffraction pattern (XRD) according to the amount of substituted calcium of a ferrite structure having a hexagonal plate shape according to an exemplary embodiment of the present invention.
14 is a diagram showing a lattice constant and a volume according to an amount of substituted calcium in a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention.
15 is a diagram showing a hysteresis loop according to the amount of substituted calcium in a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.
16 is a diagram showing magnetization and intrinsic coercivity according to the amount of substituted calcium of a ferrite structure in a hexagonal plate shape according to an embodiment of the present invention.
FIG. 17 is a diagram showing a half width (FWHM) and a crystal size of a (107) plane according to the amount of substituted calcium in a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention.
18 to 20 are diagrams illustrating results of analysis of a law of approach to saturation (LAS) according to the amount of substituted calcium in a ferrite structure in a hexagonal plate shape according to an exemplary embodiment of the present invention.
21 to 22 are diagrams showing average particle diameter, aspect ratio, and magnetic properties according to the amount of substituted calcium of a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea 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 so that the disclosed contents may be thorough and complete, and the spirit of the present invention may be 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 the other component or that a third component may be interposed therebetween. In addition, in the drawings, thicknesses of films and regions are exaggerated for effective description of technical content.

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

In the specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In addition, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, components, or a combination thereof described in the specification, and one or more other features, numbers, steps, or configurations. It is not to be understood as excluding the possibility of the presence or addition of elements or combinations thereof.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a flowchart illustrating a method of manufacturing a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention, and FIGS. 2 to 3 are a flowchart illustrating a method of manufacturing a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention. 4 is a schematic cross-sectional view of an ultrasonic spray pyrolysis apparatus (USP) for explaining a method of manufacturing a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention, and FIG. 5 is It is a schematic schematic diagram of a ferrite structure in the form of a hexagonal plate according to this.

Referring to FIG. 1, a precursor solution 100 including a first metal precursor, a second metal precursor, an iron precursor, and a salt may be prepared (S110).

According to an embodiment, the precursor solution 100 may be an aqueous solution containing at least five or more kinds of metal precursors and the salt. In other words, the precursor solution 100 may be an aqueous solution containing the first metal precursor, the second metal precursor, the iron precursor, and the salt, and at the same time, the precursor solution 100 is a third metal precursor. , And it may be an aqueous solution containing a fourth metal precursor.

According to an embodiment, the metal precursors may be nitride. Specifically, for example, the first metal precursor may be strontium nitride (Sr(NO ₃ ) ₂ ), the second metal precursor may be calcium nitride (Ca(NO ₃ ) ₂ ), and the iron precursor is Iron nitride (Fe(NO ₃ ) ₂ ) may be, the third metal precursor may be lanthanum nitride (La(NO ₃ ) ₂ ), and the fourth metal precursor may be cobalt nitride (Co(NO ₃ ) ₂ ) Can be

If, unlike the above description, when the metal precursors are chloride, chlorine gas may be generated in the thermal decomposition step of the droplet 110, which will be described later. In addition, when the metal precursors are hydroxide or acetate, the solubility of the metal precursors in water is low, so that an acid solvent may be used as a solvent for the droplet 110. Accordingly, Acidic waste may be formed in the thermal decomposition step of the droplet 110 described below.

However, according to an embodiment, the metal precursors may be the nitride. Accordingly, by-products such as the chlorine gas and the acidic waste may not be formed in the pyrolysis step of the droplet 110 described below. That is, the thermal decomposition step of the droplet 110 described below may be performed in a comparatively environmentally friendly manner.

According to an embodiment, the salt may be a material having a high solubility in the solvent of the precursor solution 100, and at the same time, may be a material having substantially no reactivity with the metal precursors.

According to an embodiment, the salt may be at least one of a chloride-based salt or a sulfide-based salt.

For example, when the salt is the chloride-based salt, the chloride-based salt _{may be at least one of sodium chloride (NaCl), barium chloride (BaCl 2} ), or potassium chloride (KCl).

For another example, when the salt is a sulfide-based salt, the sulfide-based salt is at least in sodium sulfate (K ₂ SO ₄ ), potassium sulfate (Na ₂ SO ₄ ), magnesium sulfate (MgSO ₄ ), or calcium sulfate (CaSO ₄ ). It can be either.

1, 2, and 4, ultrasonic waves may be provided to the precursor solution 100 to form droplets 110 (S120).

According to an embodiment, the precursor solution 100 may be provided to an ultrasonic spray pyrolysis apparatus (USP), and in the ultrasonic spray pyrolysis apparatus, the precursor solution 100 is atomized, and the droplet 110 ) Can be formed.

Specifically, as shown in FIG. 4, the ultrasonic spray pyrolysis apparatus includes a tubular reactor 300 including a lower surface part 300a and an upper surface part 300b opposite to the lower surface part 300a, and the reaction It may include a first inlet 320 disposed on the side of the furnace 300 to provide the precursor solution 100 to the lower surface portion 300a of the reactor 300.

Therefore, through the first inlet 320, the precursor solution 100 may be provided to the lower surface portion 300a of the reactor 300 of the ultrasonic spray pyrolysis apparatus, and at the same time, the precursor solution 100 ) Is atomized by receiving ultrasonic waves by the ultrasonic generator 310 disposed under the lower surface part 300a, so that the droplet 110 may be formed.

According to an embodiment, as described above, the droplet 110 may contain the salt. In this case, the salt may prevent aggregation between the metal precursors, and thus, the crystallinity of the intermediate oxide 120, which will be described later, may be improved.

If, unlike the above, when the precursor solution 100 and the droplet 110 do not contain the salt, aggregation between the metal precursors may occur in the droplet 110. Accordingly, the crystallinity of the intermediate oxide 120 to be described later may be lowered.

However, according to an embodiment, the droplet 110 may contain the salt, and accordingly, aggregation between the metal precursors is prevented, so that the crystallinity of the intermediate oxide 120 described below may be improved, and As a result, the crystallinity of the ferrite structure 130 manufactured using the intermediate oxide 120 may be improved. That is, the ferrite structure 130 can be easily manufactured in a hexagonal plate shape.

An intermediate oxide 120 including a first metal, a second metal, and iron may be formed by pyrolyzing the droplet 110 in an oxidizing atmosphere (S130).

According to an embodiment, the droplet 110 may be thermally decomposed in the reaction furnace 300, and accordingly, the intermediate oxide 120 including metal elements of the metal precursors may be formed.

Specifically, as shown in Figure 4, the ultrasonic spray pyrolysis device is disposed on the side of the heating unit 340 and the reaction furnace 300 for providing thermal energy to the droplet 110, the first injection port It may include a second injection hole 330 facing the (320).

Accordingly, along the carrier gas provided from the second injection port 330, the droplet 110 may be moved from the lower surface portion 300a of the reaction furnace 300 to the upper surface portion 300b, and at the same time , The droplet 110 may be thermally decomposed at a first temperature by receiving thermal energy from the heating unit 340. For example, the first temperature may be 650°C.

That is, the droplet 110 may be pyrolyzed in the carrier gas atmosphere, and in this case, the carrier gas may be an oxidizing atmosphere gas. For example, the carrier gas may be oxygen gas.

As described above, the droplet 110 is thermally decomposed, and the intermediate oxide 120 including a metal element of the metal precursors and oxygen may be generated, and at the same time, the salt of the droplet 110 is crystallized. As a result, salt crystals 200 may be formed.

Accordingly, as shown in (b) of FIG. 2, the salt crystal 200 and the intermediate oxide 120 may have a form in which the salt crystal 200 and the intermediate oxide 120 are aggregated with each other. That is, the salt crystal 200 may be formed inside the intermediate oxide 120 and at the same time cover the surface of the intermediate oxide 120. Accordingly, the salt crystal 200 may control crystal growth of the intermediate oxide 120.

As shown in Figure 4, the aggregate of the salt crystal 200 and the intermediate oxide 120 may be collected through the filter 350 disposed on the upper portion of the reactor 300, and at the same time, the intermediate Impurities (by-product) formed in the process of generating the oxide 120 may be removed through the outlet 360 disposed above the filter 350.

1, 3, and 5, an oxide containing the first metal, the iron, and oxygen by calcining the intermediate oxide 120 in an oxidizing atmosphere, and the first metal is positioned at the position of the first metal. The ferrite structure 130 in the form of a hexagonal plate in which the second metal is substituted may be manufactured (S140).

For example, the oxidizing atmosphere may be at least one of an air atmosphere or an oxygen atmosphere.

According to an embodiment, the ferrite structure 130 may be manufactured through a calcination process of the aggregate of the intermediate oxide 120 and the salt crystal 200. In this case, the intermediate oxide 120 may be crystal grown in the aggregate, and accordingly, the intermediate oxide 120 may be separated from the salt crystal 200. Accordingly, as shown in (a) of FIG. 3, the ferrite structure 130 manufactured according to the above description may have a form separated from the salt crystal 200 from each other.

Specifically, for example, as described above, the intermediate product including the metal element of the metal precursors may be calcined to a second temperature higher than the first temperature, and accordingly, the following <Chemical Formula 1> The ferrite structure 130 having a structure may be manufactured. For example, the second temperature may be 1050°C.

<Formula 1>

Sr _0.75-x La _0.25 Ca _x Fe _11.8 Co _0.2 O ₁₉

According to an embodiment, the intermediate product 120 may be grown in a specific direction according to the content of the second metal. Specifically, in a range in which the content of the second metal is greater than 0 and less than 0.4, as the content of the second metal increases, the intermediate product 120 may grow along the <00w> direction. That is, the intermediate product 120 may be crystal grown mainly in a transverse direction compared to a longitudinal direction.

Accordingly, in a range in which the content of the second metal is greater than 0 and less than 0.4, the average aspect ratio of the ferrite structure 130 may increase as the content of the second metal increases. Specifically, for example, the average aspect ratio of the ferrite structure 130 may have a range of 3.0 to 0.5.

If, unlike the above, when the content of the second metal is 0.4 or more, the average aspect ratio of the ferrite structure 130 may decrease as the content of the second metal increases.

However, according to an embodiment, the content of the second metal may be in the range of more than 0 and less than 0.4, and accordingly, as the content of the second metal increases, the ferrite structure in the form of a hexagonal plate whose average aspect ratio is increased. 130 can be manufactured.

According to an embodiment, the ferrite structure 130 has a hexagonal magnetoplumbyte type crystal structure including the first metal and the iron, but a part of the first metal is substituted with the second metal Can have.

Specifically, the substitution amount of the second metal may be in the range of more than 0 and less than 0.4, and accordingly, the ferrite structure 130 may have the substituted magnetoplumbite phase as a single phase. For example, the magnetoplum bite phase may be any one _{of SrFe 12} O ₁₉ or BaFe ₁₂ O _19.

If, unlike the above, when the substitution amount of the second metal is 0.4 or more, the ferrite structure 130 may further include a _{hemitite (α-Fe 2} O _{3) phase.} That is, the ferrite structure 130 may include both the substituted magnetoplumite phase and the hemitite phase. In general, the magnetoplumbite phase may exhibit ferromagnetic, and the hemitite phase may exhibit antiferromagnetic. Accordingly, the phase purity and crystallinity of magnetic particles of the ferrite structure 130 may be reduced, so that magnetic properties may be deteriorated.

However, according to an embodiment, the substitution amount of the second metal may be greater than 0 and less than 0.4, and accordingly, the ferrite structure 130 includes the substituted magnetoplumbyte phase alone, so that magnetic properties may be improved. I can. Specifically, in a range in which the substitution amount of the second metal is greater than 0.15 and less than 0.25, the ferrite structure 130 may have a maximum coercivity.

According to an embodiment, in the range of the substitution amount of the second metal greater than 0 and less than 0.4 and the substitution amount of the second metal is increased, the ferrite structure 130 may change the (107) plane in the X-ray diffraction pattern (XRD). The indicated 2θ value can be increased.

If, unlike the above, when the substitution amount of the second metal is 0.4 or more, the 2θ value representing the (107) plane may be substantially the same regardless of the substitution amount of the second metal. That is, as described above, when the substitution amount of the second metal is 0.4 or more, the second metal may be maximally substituted, and at the same time, the ferrite structure 130 may further include the hemitite phase.

However, according to an embodiment, the substitution amount of the second metal may be greater than 0 and less than 0.4, and accordingly, the lattice constant of the ferrite structure 130 is changed according to the substitution amount of the second metal, thereby forming the (107) plane. The indicated 2θ value can be changed.

Specifically, the ionic radius of the second metal may be smaller than the ionic radius of the first metal, and accordingly, the substituted magnetoplumbite phase may contract the crystal lattice along the c-axis (ie, longitudinal direction). . That is, in the range of the substitution amount of the second metal greater than 0 and less than 0.4, the c-lattice constant of the ferrite structure 130 may decrease as the substitution amount of the second metal increases.

In addition, as described above, the ferrite structure 130 may be manufactured by being grown substantially in a transverse direction compared to a longitudinal direction. Accordingly, as the substitution amount of the second metal increases in the range of the substitution amount of the second metal greater than 0 and less than 0.4, the ferrite structure 130 has a (107) plane compared to the intensity of the (114) plane in the X-ray diffraction pattern. The value of the intensity of may be increased, and at the same time, the value of the intensity of the (108) plane compared to the intensity of the (110) plane may be increased.

As described above, the ferrite structure 130 may be manufactured, which selectively includes the substituted magneto plumbite phase and has a hexagonal plate shape.

As shown in FIG. 5, the ferrite structure 130 may have a transverse direction as the crystal growth direction 130a, and thus, as described above, as the substitution amount of the second metal increases, the transverse direction It can grow and increase the particle size.

In addition, the ferrite structure 130 may have a longitudinal direction as an easy-axis for magnetization 130c, and at the same time, as shown in FIG. 5(b), the ferrite structure 130 May be stacked along the easy magnetization axis 130c. In particular, when the second metal has a range of more than 0.15 and less than 0.25, the ferrite structure 130 may be laminated to a maximum, and thus, as described above, the coercive force of the ferrite structure 130 is a maximum value. Can have.

According to an embodiment, the ferrite structure 130 in the form of a hexagonal plate may be included in at least one of a sintered magnet or a bonding magnet.

For example, the sintered magnet may be manufactured by sintering the powder of the ferrite structure 130 and then molding it.

For another example, the bonding magnet may be manufactured by mixing the powder of the ferrite structure 130 and a synthetic resin, and then by at least one of a compression molding method or an injection molding method.

At this time, when the magnet for bonding is manufactured by compression molding, the powder of the ferrite structure 130 and the thermosetting synthetic resin are mixed, and then provided to a mold and pressure is applied to prepare the magnet for bonding. I can. Specifically, for example, the thermosetting resin may be at least one of an epoxy resin, a phenol resin, and a urea resin.

On the other hand, when the magnet for bonding is manufactured by injection molding, the powder of the ferrite structure 130 and the thermoplastic resin may be provided in a syringe, and the mixture is extruded from the syringe into a mold, and the thermoplastic resin is It can be cured, and accordingly, the magnet for bonding can be manufactured. Specifically, for example, the thermoplastic resin may be a nylon resin.

Hereinafter, a method of manufacturing a ferrite structure having a hexagonal plate shape according to a specific experimental example of the present invention and a result of evaluation of characteristics will be described.

Preparation of a hexagonal plate-shaped ferrite structure according to Comparative Example 1

Sr(NO ₃ ) ₂ , La(NO ₃ ) ₂ , Ca(NO ₃ ) ₂ , Fe(NO ₃ ) ₂ , and Co(NO ₃ ) ₂ were prepared as metal precursors, and sodium chloride ( NaCl) was prepared.

At this time, the mixing ratio of the metal precursors was adjusted to satisfy x=0.00 in the above <Formula 1>, and at this time, the amount of cations contained in the metal precursors (that is, the strontium ion (Sr ²⁺ ), the lanthanum ions (La ²⁺ ), the calcium ions (Ca ²⁺ ), the iron ions (Fe ²⁺ ), and the total amount of the cobalt ions (Co ²⁺ ) were prepared to be 65 mmol.

The metal precursors having a controlled mixing ratio were provided to 300 mL of distilled water, and at the same time, 0.92 M of the sodium chloride was mixed and stirred for 3 hours to prepare a precursor solution.

After loading the precursor solution into a reaction furnace of an ultrasonic spray pyrolysis apparatus (UPS), ultrasonic waves were applied to the precursor solution to form droplets. At the same time, oxygen gas was provided inside the reaction furnace to move the droplets to the upper surface portion in which the heating unit was disposed.

In the oxygen gas atmosphere, the droplets are thermally decomposed at a temperature of 650° C. to crystallize the salt, and at the same time, a metal of the metal precursors and an intermediate oxide including oxygen may be prepared.

The intermediate oxide and the salt crystal were calcined at a temperature of 1050° C. for 1 hour to prepare a ferrite structure from the intermediate product. The salt crystals included with the ferrite structure were removed by dissolving in distilled water.

Accordingly, a ferrite structure in the form of a hexagonal plate according to Comparative Example 1 having a value of x=0.00 in the above <Chemical Formula 1>, that is, having <Chemical Formula 2> below was manufactured.

<Formula 2>

Sr _0.75 La _0.25 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 1

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but the precursor solution was prepared so as to satisfy x=0.05 in <Chemical Formula 1>, and <Chemical Formula 3> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 1 was manufactured.

<Formula 3>

Sr _0.70 La _0.25 Ca _0.05 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 2

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but the precursor solution was prepared so as to satisfy x=0.10 in <Chemical Formula 1>, and <Chemical Formula 4> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 2 was manufactured.

<Formula 4>

Sr _0.65 La _0.25 Ca _0.10 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 3

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but the precursor solution was prepared so as to satisfy x=0.15 in <Chemical Formula 1>, and <Chemical Formula 5> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 3 was manufactured.

<Formula 5>

Sr _0.60 La _0.25 Ca _0.15 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 4

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but by preparing the precursor solution so as to satisfy x=0.20 in <Chemical Formula 1>, and <Chemical Formula 6> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 4 was manufactured.

<Formula 6>

Sr _0.55 La _0.25 Ca _0.20 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 5

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but the precursor solution was prepared so as to satisfy x=0.25 in <Chemical Formula 1>, and <Chemical Formula 7> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 5 was manufactured.

<Formula 7>

Sr _0.60 La _0.25 Ca _0.25 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 6

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but by preparing the precursor solution so as to satisfy x=0.30 in <Chemical Formula 1>, and <Chemical Formula 8> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 6 was manufactured.

<Formula 8>

Sr _0.45 La _0.25 Ca _0.30 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Experimental Example 7

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but the precursor solution was prepared so as to satisfy x=0.40 in <Formula 1>, and <Formula 9> below instead of <Formula 2> A ferrite structure in the form of a hexagonal plate according to Experimental Example 7 was manufactured.

<Formula 9>

Sr _0.35 La _0.25 Ca _0.40 Fe _11.8 Co _0.2 O ₁₉

Preparation of a hexagonal plate-shaped ferrite structure according to Comparative Example 2

Prepared by the same method as the ferrite structure according to Comparative Example 1 described above, but by preparing the precursor solution so as to satisfy x=0.60 in <Chemical Formula 1>, and <Chemical Formula 10> below instead of <Chemical Formula 2> A ferrite structure in the form of a hexagonal plate according to Comparative Example 2 was manufactured.

<Formula 10>

Sr _0.15 La _0.25 Ca _0.60 Fe _11.8 Co _0.2 O ₁₉

Of the first metal (eg, strontium), and the second metal (eg, calcium) of the hexagonal plate-shaped ferrite structure according to Comparative Example 1, Comparative Example 2, and Experimental Examples 1 to 7 described above. The quantity is written in <Table 1> below.

Sr (first metal) Ca (second metal) Comparative Example 1 0.75 0.00 Experimental Example 1 0.70 0.05 Experiment Example 2 0.65 0.10 Experiment Example 3 0.60 0.15 Experiment Example 4 0.55 0.20 Experimental Example 5 0.50 0.25 Experimental Example 6 0.45 0.30 Experimental Example 7 0.35 0.40 Comparative Example 2 0.15 0.60

6 is a scanning electron microscope (SEM) image immediately after a step of pyrolyzing a droplet and a step of calcining an intermediate oxide in a manufacturing step of a ferrite structure having a hexagonal plate shape according to an exemplary embodiment of the present invention.

Referring to FIG. 6A, a mixture of the intermediate oxide and the salt crystal formed immediately after the step of pyrolyzing the droplet was photographed in the manufacturing step of the hexagonal plate-shaped ferrite structure according to the exemplary embodiment of the present invention.

In addition, referring to FIG. 6B, a mixture of the ferrite structure formed immediately after the step of calcining the intermediate oxide and the salt crystal was photographed during the manufacturing step of the ferrite structure.

As described above with reference to FIGS. 1 to 3, the salt crystals were precipitated in the intermediate oxide, and compared to the surface of the ferrite structure, the surface of the intermediate oxide was found to have relatively less salt crystals. I can.

In addition, compared to the intermediate oxide, it was confirmed that the ferrite structure had a hexagonal plate shape.

7 to 9 are scanning electron microscope (SEM) images of a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention in a shape according to the amount of substituted calcium.

7 to 9, the amount of substitution of calcium (that is, the second metal) in the hexagonal plate-shaped ferrite structure according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 of the present invention The surface along was observed. The average particle diameter, average thickness, and average aspect ratio of the ferrite structure were prepared in Table 2 below.

Particle diameter [nm] Thickness [nm] Average aspect ratio (D/t) Average (D) Standard Deviation Mean(t) Standard Deviation Comparative Example 1 499.2 217.7 186.3 62.2 2.7 Experimental Example 1 618.8 252.9 191.4 58.8 3.2 Experiment Example 2 837.2 280.5 210.6 51.3 4.0 Experiment Example 3 955.5 293.0 174.0 48.0 5.5 Experiment Example 4 1111.5 599.6 151.6 46.3 7.3 Experimental Example 5 1145.0 495.6 160.4 62.4 7.1 Experimental Example 6 1286.8 611.9 182.4 62.2 7.1 Experimental Example 7 1314.3 740.9 141.2 62.5 9.3 Comparative Example 2 2535.6 1007.3 299.3 100.7 8.5

As can be seen from Table 2 and FIGS. 7 to 9, it can be seen that as the concentration of calcium increases, the particle diameter of the ferrite structure increases. On the other hand, the thickness of the ferrite structure depends on the amount of calcium. You can see that it changes. That is, when the amount of calcium is 0.4 or less, the thickness of the ferrite structure has a value within about 210 nm, but when the amount of calcium is 0.4 or more, it can be seen that the thickness of the ferrite structure increases by about 90 nm or more.

Accordingly, it can be seen that when the amount of calcium is 0.4 or less, the average aspect ratio of the ferrite structure calculated by the particle diameter and thickness of the ferrite structure increases as the amount of calcium increases, whereas the amount of calcium When this was 0.4 or more, it was confirmed that the average aspect ratio of the ferrite structure was decreased.

That is, when the amount of calcium is 0.4, it can be seen that the average aspect ratio of the ferrite structure has a maximum value.

10 is a scanning electron microscope (SEM) image of a stacked form of a hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.

Referring to FIG. 10, as described above with reference to FIGS. 1 to 3, it can be seen that the hexagonal plate-shaped ferrite structure according to Experimental Example 7 of the present invention is stacked along the easy magnetization axis.

On the other hand, it was confirmed that the ferrite structure in the form of a hexagonal plate according to Comparative Example 1 of the present invention was not substantially laminated.

11 is a diagram illustrating particle distribution of the ferrite structure according to the amount of substituted calcium in the hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.

Referring to FIG. 11, the ferrite structures of the hexagonal plate shape according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 of the present invention have a larger particle diameter as the concentration of calcium increases. You can see that the amount of is increased. Accordingly, as described above with reference to FIG. 9, it can be seen that as the amount of calcium increases, the average particle diameter of the ferrite structure increases.

12 to 13 are diagrams illustrating an X-ray diffraction pattern (XRD) according to the amount of substituted calcium of a ferrite structure having a hexagonal plate shape according to an exemplary embodiment of the present invention.

12 to 13, the crystal structures of the hexagonal plate-shaped ferrite structures according to Comparative Example 1, Experimental Example 4 (x=0.20), Experimental Example 7 (x=0.40), and Comparative Example 2 of the present invention are shown. Confirmed.

When the amount of calcium is less than 0.4, it can be seen that _{the ferrite structure has the magnetoplumbyte phase of SrFe 12} O _{19 as a single phase.}

On the other hand, when the amount of calcium is 0.4 or more, it can be seen that _{the ferrite structure further includes the hemitite (α-Fe 2} O _{3) phase.} That is, when the amount of calcium is 0.4, it can be seen that the calcium is maximally substituted on the magnetoplumbite.

Specifically, as shown in FIG. 13, when the amount of calcium is less than 0.4, it can be seen that the 2θ value of the (107) plane of the ferrite structure increases as the amount of calcium increases.

Accordingly, compared to the strontium ion having an ionic radius of 0.118 nm, it can be seen that calcium ions having an ionic radius of 0.099 nm are substituted at the strontium ions, and the lattice constant of the ferrite structure is changed.

In addition, when the amount of calcium is less than 0.4, as the amount of calcium increases, the intensity of the (008) plane compared to the intensity of the (110) plane (that is, I ₍₀₀₈₎ / I ₍₁₁₀₎ ), and (114) It can be seen that the intensity of the (107) plane (that is, I ₍₁₀₇₎ / I _{(114)) increases compared to the intensity of the plane.} That is, in the range where the amount of calcium is less than 0.4, it can be seen that as the amount of calcium increases, the growth in the <00w> direction perpendicular to the easy magnetization axis is mainly made compared to the growth in the direction of the easy magnetization axis. I can.

14 is a diagram showing a lattice constant and a volume according to an amount of substituted calcium of a ferrite structure in a hexagonal plate shape according to an exemplary embodiment of the present invention.

Referring to FIG. 14, as described above with reference to FIG. 13, the hexagonal plate-shaped ferrite structures according to Comparative Example 1, Experimental Examples 1 to 7 and Comparative Example 2 of the present invention have a substituted amount of calcium. As it increases, it can be seen that the lattice constant (ie, c-lattice constant) in the direction of the easy magnetization axis decreases.

As described above with reference to <Table 2>, it can be seen that as the amount of calcium increases, the particle diameter of the ferrite structure increases, but the thickness decreases, and accordingly, the volume of the ferrite structure decreases. Able to know.

15 is a diagram showing a hysteresis loop according to the amount of substituted calcium of a ferrite structure in a hexagonal plate shape according to an embodiment of the present invention.

Referring to FIG. 15, magnetization of an electric field applied to a hexagonal plate-shaped ferrite structure according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 of the present invention was confirmed.

As described above with reference to FIGS. 12 to 13, the ferrite structure may have the magneto plumbite phase as a single phase when the amount of calcium is less than 0.4. Accordingly, it can be seen that when the amount of calcium is less than 0.4, the ferrite structure exhibits substantially the same hysteresis curve.

When the amount of calcium is in the range of 0.4 or more, the ferrite structure may further include the hemitite phase. However, the amount of the hemitite phase may be relatively small, and accordingly, it was confirmed that the ferrite structure exhibits a single-phased ferroelectric behavior.

However, compared to the case where the amount of calcium was less than 0.4, it was confirmed that the magnetization of the ferrite structure was reduced.

16 is a diagram showing magnetization and intrinsic coercivity according to the amount of substituted calcium of a ferrite structure in a hexagonal plate shape according to an embodiment of the present invention.

Referring to FIG. 16, magnetization at 25kOe of the hexagonal plate-shaped ferrite structure according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 of the present invention (M _25kOe ), residual magnetism (M _r , remanence ), and intrinsic coercivity (H _C ) were written in <Table 3>.

M _25kOe [emu/g] M _r [emu/g] H _C [Oe] M _r /M _25kOe [%] Comparative Example 1 71.364 38.233 7035.1 53.575 Experimental Example 1 71.862 38.427 7310.9 53.473 Experiment Example 2 71.647 38.320 7580.4 53.484 Experiment Example 3 72.837 38.688 7745.5 53.116 Experiment Example 4 72.647 38.854 7880.4 53.483 Experimental Example 5 71.401 38.567 7471.9 54.015 Experimental Example 6 72.669 38.926 7415.9 53.566 Experimental Example 7 66.886 35.288 7388.6 52.758 Comparative Example 2 60.426 31.510 7178.0 52.146

Referring to <Table 3> and FIG. 16, as described above with reference to FIG. 15, the magnetization (M _25kOe ) of the ferrite structure has a substantially constant value when the amount of calcium is less than 0.4, As the amount increases to 0.4 or more, it can be seen that it decreases. That is, it contains calcium to 0.4 or more, and the ferrite structure further includes the hemitite phase, and thus, the crystallinity of the ferrite structure As a result, it can be seen that the magnetization of the ferrite structure is reduced.

It can be seen that the intrinsic coercivity (H _C ) of the ferrite structure has a maximum value when the amount of calcium is 0.2. In addition, it can be seen that the ferrite structure including calcium has a higher coercivity than the hexagonal plate-shaped ferrite structure according to Comparative Example 1.

FIG. 17 is a diagram showing the half width (FWHM) and crystal size of the (107) plane according to the amount of substituted calcium in the hexagonal plate-shaped ferrite structure according to an embodiment of the present invention.

Referring to FIG. 17, the half width of the (107) plane of the hexagonal plate-shaped ferrite structure according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 of the present invention described above with reference to FIGS. 12 to 13 , And the size of the crystal calculated by the X-ray diffraction pattern of the ferrite structure was confirmed.

As shown in FIG. 17, it can be seen that in the range where the amount of calcium is less than 0.40, the half width of the (107) plane of the ferrite structure is reduced. In addition, it can be seen that the half width of the (107) plane of the ferrite structure is substantially constant in a range in which the amount of calcium in which the calcium is maximally substituted on the magnetoplumbite is 0.40 or more.

Therefore, in the range where the amount of calcium is less than 0.40, it can be seen that as the amount of calcium increases, the crystallinity of the calcium-substituted magnetoplumbite phase increases, and accordingly, the magnetization of the ferrite structure is substantially constant. In addition, it was confirmed that in the range where the amount of calcium was 0.40 or more, the hemitite phase was formed, thereby reducing the magnetization of the ferrite structure.

As described above with reference to <Table 2>, it was confirmed that the amount of calcium was increased, and the calculated crystal size of the ferrite structure was increased.

18 to 20 are diagrams illustrating results of analysis of a law of approach to saturation (LAS) according to the amount of substituted calcium in a hexagonal plate-shaped ferrite structure according to an exemplary embodiment of the present invention.

18 to 20, analysis results of the hexagonal plate-shaped ferrite structures according to Comparative Example 1, Experimental Examples 1 to 7, and Comparative Example 2 according to the saturation approach law of the present invention were confirmed.

16 and <Table 3>, it can be seen that the intrinsic coercivity of the ferrite structure becomes maximum when the amount of calcium is 0.2. In this case, as shown in FIGS. 8 to 10, it can be seen that the amount of calcium has a value greater than 0.2, and the shape of the ferrite structure has a substantially hexagonal plate shape.

That is, it can be seen that the ferrite structure has the shape of the hexagonal plate, and the intrinsic coercivity is reduced, and accordingly, it was confirmed that there are factors affecting the intrinsic coercivity in addition to the shape of the ferrite structure.

Therefore, in order to confirm the factor affecting the intrinsic coercivity, an analysis by the saturation approach law of the ferrite structure according to the substitution amount of calcium was performed.

In general, the saturation approach law is a method used to determine the local crystalline anisotropy of a magnetic material, and the dependence of the coercive force on magnetization can be calculated using the following <Equation 1>.

<Equation 1>

Here, A/H is an inhomogeneity of the magnetic material, χ _P H is a magnetization value due to an electric field, and B/H ² is a value related to a magnetocrystalline anisotropy parameter.

Accordingly, by substituting the experimental results of the ferrite structure in the above <Equation 1>, graphs as shown in FIGS. 18 to 20 were derived. The goodness of the curve fit (R ² ) of the ferrite structure was written in <Table 4> below.

Curve goodness-of-fit (R ² ) Comparative Example 1 0.99951 Experimental Example 1 0.99931 Experiment Example 2 0.99939 Experiment Example 3 0.99933 Experiment Example 4 0.99938 Experimental Example 5 0.99949 Experimental Example 6 0.99945 Experimental Example 7 0.99925 Comparative Example 2 0.99911

As can be seen from <Table 4>, it can be seen that the ferrite structure substantially corresponds to the above <Equation 1>, and accordingly, the A constant, B constant, and χ _P constant of the ferrite structure below < It was written in Table 5>.

A (Χ10 ³ ) B (Χ10 ⁶ ) χ _p (Χ10 ^-4 ) Comparative Example 1 2.7792 15.6282 3.4675 Experimental Example 1 2.9710 16.2676 3.6570 Experiment Example 2 2.9983 16.4826 3.8692 Experiment Example 3 3.0046 17.6702 3.9233 Experiment Example 4 2.9983 18.2826 3.8692 Experimental Example 5 3.0847 18.2278 3.5873 Experimental Example 6 3.0714 17.1724 3.8744 Experimental Example 7 3.6815 17.1256 1.7774 Comparative Example 2 3.9001 16.7892 8.1328

As can be seen from <Table 5>, it can be seen that the A constant representing the non-uniformity of the magnetic material is substituted with 0.4 or more of the calcium, and the value is increased. Accordingly, it can be seen that the ferrite structure further includes the hemitite phase in the range of 0.4 or more of the calcium substitution. In general, in a magnetic material having a hexagonal crystal structure, the B constant is < It can be calculated as Equation 2>.

<Equation 2>

Here, H _A is an anisotropy field, and K ₁ is a magnetocrystalline anisotropy constant.

_{At this time, the values of H A} and K _{1 of the ferrite structure calculated using M 25kOe} (here, _{substituted for M S} ) written in <Table 3> and the B constant written in <Table 5> are < It was written in Table 6>.

H _A (Cal.) [kOe] K ₁ (Cal.) [Χ10 ⁶ erg/cm ³ ] Comparative Example 1 15.311 2.8955 Experimental Example 1 15.621 2.9748 Experiment Example 2 15.724 2.9854 Experiment Example 3 16.280 3.1424 Experiment Example 4 16.560 3.1881 Experimental Example 5 16.535 3.1287 Experimental Example 6 16.049 3.0907 Experimental Example 7 16.028 2.8409 Comparative Example 2 15.869 2.5412

As can be seen from <Table 6>, the H _A of the ferrite structure and the The value of K ₁ confirmed that the amount of calcium increased below 0.2 (ie, Comparative Example 1, and Experimental Examples 1 to 4). Accordingly, when the amount of calcium is 0.2 or less, lateral growth is mainly generated compared to the longitudinal growth of the ferrite structure, and at the same time, the ferrite structure is stacked, so that the H _A and the It can be seen that the value of K ₁ increases. On the other hand, when the amount of calcium is more than 0.2, the H _A of the ferrite structure and the It was confirmed that the value of _{K 1 decreased.} Accordingly, the calcium is substituted, and the purity of the magnetoplumbite phase is reduced, so that the H _A and the It can be seen that the value of K _{1 decreases.}

In this case, in general, the anisotropy of the coercive force of the magnetic material can be calculated by the following <Equation 3>.

<Equation 3>

Here, α is a shape constant, and N _d and H _d are values related to a demagnetization coefficient.

Accordingly, it can be seen that the intrinsic coercivity of the ferrite structure _{is proportional to the anisotropic field (H A} ) or the magnetic crystal anisotropy constant (K _{1 ).}

As described above, it can be seen that the magnetization of the ferrite structure is determined by the purity of the crystal phase of the ferrite structure, and it was confirmed that the intrinsic coercivity of the ferrite structure is mainly determined by the self-crystal anisotropy of the ferrite structure.

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 who have acquired ordinary knowledge in this technical field should understand that many modifications and variations are possible without departing from the scope of the present invention.

100: precursor solution
110: droplet
120: intermediate oxide
130: ferrite structure
130a: crystal growth direction
130c: easy-axis for magnetization
200: salt crystal
300: reactor
300a: lower surface
300b: upper surface
310: ultrasonic generator
320: first inlet
330: second inlet
340: heating part
350: filter
360: outlet

Claims (15)

A first metal containing strontium (Sr) and a hexagonal magnetoplumbite crystal structure containing iron (Fe), including those in the shape of a hexagonal plate,
The crystal structure includes that a part of the first metal is substituted with a second metal including calcium (Ca), and is represented by the following <Chemical Formula 1>,
<Formula 1>
Sr _0.75-x La _0.25 Ca _x Fe _11.8 Co _0.2 O ₁₉ (atomic ratio)
(0<x<4)
Ferrite structure in the form of a hexagonal plate, including those having a single phase magnetoplumite.
The method of claim 1,
The average aspect ratio (aspect ratio), including those having a range of 3.0 to 9.5, a ferrite structure in the form of a hexagonal plate.
The method of claim 1,
A ferrite structure in the form of a hexagonal plate, comprising increasing an average aspect ratio as the amount of the second metal increases.
The method of claim 1,
When x in <Formula 1> has a range of more than 0.15 and less than 0.25, a ferrite structure in the form of a hexagonal plate, including those having a maximum coercivity.
The method of claim 1,
A ferrite structure having a hexagonal plate shape, comprising increasing a 2θ value representing a (107) plane in an X-ray diffraction pattern (XRD) as the amount of the second metal increases.
The method of claim 1,
A ferrite structure in the form of a hexagonal plate, comprising increasing the intensity of the (107) plane compared to the intensity of the (114) plane in the X-ray diffraction pattern (XRD) as the amount of the second metal increases.
delete The method of claim 1,
A hexagonal plate-shaped ferrite structure comprising at least one of lanthanum (La) and cobalt (Co).
A sintered magnet comprising a ferrite structure in the form of a hexagonal plate according to claim 1.
A magnet for bonding comprising a ferrite structure in the form of a hexagonal plate according to claim 1.
Preparing a precursor solution including a first metal precursor, a second metal precursor, an iron precursor, and a salt;
Providing ultrasonic waves to the precursor solution to form droplets;
Pyrolyzing the droplet in an oxidizing atmosphere to form an intermediate oxide including a first metal, a second metal, and iron; And
Calcination of the intermediate oxide in an oxidizing atmosphere to prepare a hexagonal plate-shaped ferrite structure, which is an oxide containing the first metal, the iron, and oxygen, and the second metal is substituted at the position of the first metal Including,
The ferrite structure is represented by the following <Chemical Formula 1>,
<Formula 1>
Sr _0.75-x La _0.25 Ca _x Fe _11.8 Co _0.2 O ₁₉ (atomic ratio)
(0<x<4)
A method of manufacturing a ferrite structure in the form of a hexagonal plate, including those having a single phase magnetoplumite.
The method of claim 11,
The step of pyrolyzing the droplets is performed at a first temperature,
The step of calcining the intermediate oxide comprises performing at a second temperature higher than the first temperature.
The method of claim 11,
The step of pyrolyzing the droplets includes forming the intermediate oxide and simultaneously depositing the salt into crystals,
Immediately after the step of preparing the ferrite structure, a method of manufacturing a ferrite structure in a hexagonal plate shape comprising the step of removing the crystal.
The method of claim 11,
The precursor solution is a method of manufacturing a ferrite structure having a hexagonal plate shape including a third metal precursor and a fourth metal precursor.
The method of claim 14,
The third metal precursor is lanthanum nitrate,
The fourth metal precursor is a method of manufacturing a ferrite structure having a hexagonal plate shape including cobalt nitrate.

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