Manganese carbide-based magnetic material and preparation method therefor

Abstract

The present invention relates to a manganese carbide-based magnetic material and a preparation method thereof. Specifically, the present invention relates to a manganese carbide-based magnetic material enabling the adjustment of the magnetization temperature coefficient and saturation magnetization according to the intended purpose, and a preparation method therefor.

Description

Manganese carbide-based magnetic material and method for manufacturing the same

[0001] The present invention relates to a manganese carbide-based magnetic material and a method for manufacturing the same. Specifically, the invention relates to a manganese carbide-based magnetic material capable of controlling the magnetization temperature coefficient and saturation magnetization according to the intended purpose, and a method for manufacturing the same. The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2024-0141316 filed with the Korean Intellectual Property Office on October 16, 2024, the entire contents of which are incorporated into the present invention.

[0002] The magnetization of most materials decreases with increasing temperature within a temperature range where no structural or magnetic phase transition occurs. For example, FeRh, which is antiferromagnetic at room temperature and ferromagnetic at elevated temperatures, is metamagnetic within a very narrow temperature range, and magnetization enhancement occurs at the phase transition temperature. The reduction in magnetization due to agitation has primarily limited the operating temperatures of well-known Nd-Fe-B magnetic materials. In other words, the thermal stability of information bits in magnetic recording media is critical. Thermally induced magnetization fluctuation noise is considered a prominent source of noise in read heads used in hard disk drives.

[0003] Therefore, it is highly desirable to find a material that can withstand the thermal degradation of magnetization. For example, Y3Ga x Fe 5-x O 12 Some magnetic materials may increase in magnetization as temperature increases, but this behavior usually disappears at temperatures above room temperature.

[0004] The Mn4C manganese carbide magnetic material has the characteristic that magnetization increases linearly as temperature increases in a temperature range of about 50K to 600K. As a result, it can prevent a decrease in magnetization caused by thermal fluctuations and is a magnetic material that can be used when thermal magnetic stability is required.

[0005] Meanwhile, Mn4C has a simple cubic perovskite crystal structure. Figure 1 is a schematic diagram showing the crystal structure of Mn4C. As shown in Figure 1, the chemical formula of Mn4C is (Mn II )3Mn I It can be written in C, where Mn I is an atom located at the vertices of the cube, and Mn II is a face-centered atom, and carbon is a body-centered atom. Mn surrounds the C atom in eight faces. II The atom is strongly bonded to the C atom. Therefore, Mn II Atoms are chemically stable.

[0006] The technical problem to be solved by the present invention is to provide a manganese carbide-based magnetic material with adjustable magnetization temperature coefficient and saturation magnetization, and a method for manufacturing the same.

[0007] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0008] One embodiment of the present invention is a composition formula Mn 3+x Ga 1-x A manganese carbide-based magnetic material is provided, represented by C (0≤x<1).

[0009] Another embodiment of the present invention provides a method for manufacturing a manganese carbide-based magnetic material according to one embodiment of the present invention, comprising the steps of: melting manganese, gallium, and a carbon-based compound together; and cooling the melt of the manganese, gallium, and carbon-based compound to produce an ingot.

[0010] According to one embodiment of the present invention, the magnetization temperature coefficient and saturation magnetization of the manganese carbide-based magnetic body may change depending on the content of Ga substituting Mn, and the composition of the manganese carbide-based magnetic body is the composition formula Mn 3+x Ga 1-x By adjusting C (0≤x<1), the magnetization temperature coefficient and saturation magnetization can be controlled according to the desired outcome.

[0011] The effects of the present invention are not limited to those described above, and unmentioned effects will be clearly understood by those skilled in the art from the present specification and the accompanying drawings.

[0012] Figure 1 is a schematic diagram showing the crystal structure of Mn4C.

[0013] Figure 2 is a diagram showing the XRD patterns of manganese carbide-based magnetic materials prepared in Examples 1 to 6.

[0014] FIG. 3 is a graph showing the saturation magnetization as a function of temperature for the manganese carbide-based magnetic materials of Examples 1 to 6 and the magnetization temperature coefficient (△M / △T) for each example.

[0015] FIG. 4 is Example 1 (Mn 3.25 Ga 0.75 This shows the MH graph for the magnetic material of C at a temperature of 5K and the saturation magnetization intensity measured for the magnetic materials of Examples 1 to 6 at temperature conditions of 5K and 300K.

[0016] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0017] Throughout this specification, when a component is described as being located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0018] Throughout the entire specification, the unit "parts by weight" may refer to the ratio of weight between each component.

[0019] Throughout this specification, "magnetization temperature coefficient" refers to the rate of change of the magnetization intensity (emu / g) of a magnetic material with respect to temperature (K), and may also be expressed as "△M / △T" or "dM / dT". More specifically, the "magnetization temperature coefficient" may be determined as the rate of change of the saturation magnetization intensity (emu / g) of a magnetic material with respect to temperature (K). Throughout this specification, unless otherwise noted, the unit of the magnetization temperature coefficient is emu·g -1 ·K -1 - am.

[0020] Throughout this specification, "A and / or B" means "A and B, or A or B".

[0021] One embodiment of the present invention is a composition formula Mn 3+x Ga 1-x A manganese carbide-based magnetic material is provided, represented by C (0≤x<1).

[0022] According to one embodiment of the present invention, the manganese carbide-based magnetic material comprises an Mn4C type crystalline phase, and the fraction of the Mn4C type crystalline phase may be 90% to 100%.

[0023] More preferably, the fraction of the Mn4C type crystal phase may be 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more.

[0024] According to one embodiment of the present invention, the manganese carbide-based magnetic body may have a perovskite crystal structure.

[0025] According to one embodiment of the present invention, the Mn4C type crystal phase is one in which a portion of Mn in the Mn4C crystal structure is substituted with Ga. More specifically, Mn I It is possible that some of the Mn atoms at the position have been substituted with Ga.

[0026] According to one embodiment of the present invention, the manganese carbide-based magnetic material may exhibit diffraction peaks of crystal planes (111), (200), (220), (311), and (222), respectively, at 2θ values ​​near 40°, 48°, 69°, 82°, and 88°, respectively, as a result of XRD analysis. That is, the manganese carbide-based magnetic material according to one embodiment of the present invention may have the same crystal structure as the crystal structure of a gallium-unsubstituted Mn4C magnetic material.

[0027] According to one embodiment of the present invention, the manganese carbide-based magnetic material has a magnetization strength that increases or begins to decrease in a temperature range of 30K to 80K, for example, a temperature range of 50K to 70K, and can increase or decrease linearly in a temperature range of 540K to 640K, for example, a temperature range of 560K to 600K.

[0028] A manganese carbide-based magnetic material according to one embodiment of the present invention exhibits a magnetization intensity that increases or decreases linearly within the aforementioned temperature range, and does not undergo a degradation phenomenon in which the magnetization intensity drops sharply, allowing the magnetization intensity to be maintained within a certain range. Accordingly, the manganese carbide-based magnetic material according to one embodiment of the present invention can maintain a stable magnetization state within an operating temperature range, and it is possible to control the degree of change in magnetization intensity according to temperature and magnetization intensity as intended.

[0029] According to one embodiment of the present invention, the magnetization temperature coefficient of the manganese carbide-based magnetic material may change depending on the ratio of Ga substituting Mn, and the compositional formula Mn of the manganese carbide-based magnetic material 3+x Ga 1-x The magnetization temperature coefficient can be controlled according to the purpose by adjusting the value of x in C (0≤x<1). Specifically, the larger x is in the above compositional formula, that is, the lower the ratio of Ga, the higher the magnetization temperature coefficient of the manganese carbide-based magnetic material can be.

[0030] According to one embodiment of the present invention, when x of the composition formula is 0.8 or higher, 0.81 or higher, 0.82 or higher, 0.83 or higher, 0.84 or higher, or 0.85 or higher, the magnetization temperature coefficient of the manganese carbide-based magnetic material satisfying this can be 0 or higher. When x of the composition formula satisfies the above-described range, the magnetization strength of the manganese carbide-based magnetic material can increase linearly as the temperature increases.

[0031] According to one embodiment of the present invention, when x of the composition formula is 0.8 or more, 0.81 or more, 0.82 or more, 0.83 or more, 0.84 or more, or 0.85 or more, the magnetization temperature coefficient of the manganese carbide-based magnetic material satisfying this may be 0 or more and 0.5 or less, 0 or more and 0.4 or less, 0 or more and 0.3 or less, 0 or more and 0.2 or less, 0 or more and 0.1 or less, 0 or more and 0.05 or less, or 0 or more and 0.01 or less.

[0032] According to one embodiment of the present invention, when x of the composition formula is 0.8 or less, 0.79 or less, 0.78 or less, 0.77 or less, 0.76 or less, or 0.75 or less, the magnetization temperature coefficient of the manganese carbide-based magnetic material satisfying this may be 0 or less. When x of the composition formula satisfies the above-described range, the magnetization intensity of the manganese carbide-based magnetic material may decrease linearly as the temperature increases.

[0033] According to one embodiment of the present invention, when x of the composition formula is 0.8 or less, 0.79 or less, 0.78 or less, 0.77 or less, 0.76 or less, or 0.75 or less, the magnetization temperature coefficient of the manganese carbide-based magnetic material satisfying this may be -0.5 or more and 0 or less, -0.4 or more and 0 or less, -0.3 or more and 0 or less, -0.2 or more and 0 or less, -0.1 or more and 0 or less, -0.095 or more and 0 or less, -0.09 or more and 0 or less, -0.05 or more and 0 or less, or -0.01 or more and 0 or less.

[0034] According to one embodiment of the present invention, the magnetization temperature coefficient (△M / △T) of the manganese carbide-based magnetic material may satisfy the following mathematical formula 1.

[0035] [Mathematical Formula 1]

[0036]

[0037] In the above mathematical formula 1, △M / △T is the magnetization temperature coefficient [emu·g -1 ·K -1 ] and x is the same as x in the above manganese carbide-based magnetic material composition formula, and a = -0.0107 (95% confidence interval: [-0.0484, 0.0270]), b = -1.7091 (95% confidence interval: [-3.9450, 0.5268]), c = 0.0722 (95% confidence interval: [-0.0334, 0.0722]).

[0038] According to one embodiment of the present invention, the saturation magnetization of the manganese carbide-based magnetic material may change depending on the ratio of Ga substituting Mn, and the compositional formula of the manganese carbide-based magnetic material Mn 3+x Ga 1-x C (0 <x<1)에서의 x값을 조절함으로써 포화 자화를 목적에 따라 제어할 수 있다. 구체적으로. 상기 조성식의 x가 작을수록, 즉 Ga의 비율이 클수록 탄화 망간계 자성체의 포화 자화(M s ) can increase.

[0039] A manganese carbide-based magnetic material according to one embodiment of the present invention may have a saturation magnetization strength in the range of 1 to 200 emu / g.

[0040] According to one embodiment of the present invention, when x of the composition formula is 0.5 or less, the saturation magnetization strength of the manganese carbide-based magnetic material at 300 K may be 35 emu / g or more, 40 emu / g or more, 45 emu / g or more, or 50 emu / g or more.

[0041] According to one embodiment of the present invention, when x of the composition formula is 0.25 or less, the saturation magnetization strength of the manganese carbide-based magnetic material at 300 K may be 50 emu / g or more, 55 emu / g or more, 60 emu / g or more, or 65 emu / g or more.

[0042] According to one embodiment of the present invention, the saturation magnetization (M) of the manganese carbide-based magnetic material at a temperature of 5 K s ) may satisfy the following mathematical formula 2.

[0043] [Mathematical Formula 2]

[0044]

[0045] In the above mathematical formula 2, x is the same as x in the above manganese carbide-based magnetic material composition formula, 107≤a1≤119, and -120≤b1≤-102.

[0046] According to one embodiment of the present invention, the saturation magnetization (M) of the manganese carbide-based magnetic material at a temperature of 300 K s ) may satisfy the following mathematical formula 3.

[0047] [Mathematical Formula 3]

[0048]

[0049] In the above mathematical formula 3, x is the same as x in the above manganese carbide-based magnetic material composition formula, 86≤a2≤92, and -84≤b2≤-78.

[0050] Another embodiment of the present invention provides a method for manufacturing a manganese carbide-based magnetic material according to one embodiment of the present invention, comprising the steps of: melting manganese, gallium, and a carbon-based compound together; and cooling the melt of the manganese, gallium, and carbon-based compound to produce an ingot.

[0051] According to one embodiment of the present invention, it may be preferable to use high-purity manganese carbide magnetic material by using manganese, gallium, and carbon-based compounds as raw materials used to manufacture a magnetic material.

[0052] According to one embodiment of the present invention, the carbon-based compound may be one or more selected from graphite, graphene, carbon nanotubes, and carbon fibers.

[0053] According to one embodiment of the present invention, the step of melting the manganese, gallium, and carbon-based compound together may be performed by an induction heating method.

[0054] According to one embodiment of the present invention, the manganese, gallium, and carbon-based compounds are in the compositional formula Mn of the manganese carbide-based magnetic material to be manufactured. 3+x Ga 1-x They can be mixed in stoichiometric ratios satisfying C (0≤x<1) and melted together.

[0055] According to one embodiment of the present invention, the induction heating may be performed at a temperature of 1000 to 3500 ℃.

[0056] According to one embodiment of the present invention, cooling the molten material may be performed by natural cooling or by forced cooling. The forced cooling is 10 1 K / min to 10 5 Cooling rate of K / min, e.g., 10 2 K / min to 10 5 K / min, 10 3 K / min to 10 5 K / min, 10 4 K / min to 10 5 Manganese carbide alloy ingots can be manufactured by cooling to a temperature of 200 K to 300 K at a cooling rate of K / min.

[0057] Compositional formula of the manganese carbide-based magnetic material to be manufactured: Mn 3+x Ga 1-x When x in C is 0 or greater and less than 0.95, the homogeneity of the alloy ingot obtained by natural cooling of a melt of manganese, gallium, and carbonaceous compounds can be high without additional processing.

[0058] The above alloy ingot can be crushed and pulverized, and then the obtained powder can be magnetically separated to remove impurities and obtain a manganese carbide-based magnetic material of the desired purity. At this time, the method of crushing is not particularly limited.

[0059] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0060] Examples 1 to 6. Preparation of Gallium-Substituted Manganese Carbide-Based Magnetic Materials

[0061] As raw materials, manganese metal flakes (purity: 99.95%, source: Taewon Science), high-purity graphite (purity: 99.5%, source: Taewon Science), and gallium (purity: 99.999%, source: Taewon Science) were prepared to satisfy the respective content ratios of Examples 1 to 6 shown in Table 1 below.

[0062] Raw materials were loaded into an alumina crucible, introduced into an induction heating chamber, and induction heated to melt the manganese metal flakes, graphite, and gallium together. The molten material was naturally cooled to room temperature to obtain an alloy ingot magnetic body.

[0063] For the alloy ingot of Example 6, an additional step of heat treatment at 1000°C and rapid cooling with water was performed.

[0064] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Composition Formula Mn 3+x Ga 1-x x 0.25 0.5 0.65 0.75 0.85 0.95 in C composition formula Mn 3.25 Ga 0.75 CMn 3.5 Ga 0.5 CMn 3.65 Ga 0.35 CMn 3.75 Ga 025 CMn 3.85 Ga 0.15 CMn 3.95 Ga 0.05 C

[0065]

[0066] XRD analysis

[0067] To analyze the X-ray diffraction pattern of the magnetic material prepared in the example, the alloy ingot was crushed using hand grinding until the particle size was 1 mm or less. X-ray diffraction analysis (XRD analysis) (measurement equipment: D / MAX-2500V / PO, Rigaku; measurement conditions: Cu-Kα ray) was performed on the crushed magnetic material powder.

[0068] Figure 2 shows the XRD patterns of the manganese carbide-based magnetic materials prepared in Examples 1 to 6. In Figure 2, the peak marked with * is Mn 23 This refers to the C6 crystal phase. Referring to FIG. 2, peaks corresponding to the diffraction peaks of the (111), (200), and (220) crystal planes of the Mn4C crystal phase were observed in all embodiments, which means that the manganese carbide-based magnetic material according to one embodiment of the present invention has the same crystal structure as the pure Mn4C magnetic material without gallium substitution. Furthermore, it was confirmed that the manganese carbide-based magnetic material produced by the manufacturing method according to the present invention is produced with excellent purity, as almost no impurity peaks corresponding to the secondary phase of Mn4C were observed.

[0069] The fraction of the Mn4C crystal phase among manganese carbide-based magnetic materials measured by XRD analysis is shown in Table 2.

[0070] x (Mn 3+x Ga 1-x C)Mn4C Phase Fraction (%)0.95~100%0.85~90-92%0.75~100%0.65~95%0.50~95-97%0.25~90-92%

[0071] As shown in Table 2, the manganese carbide-based magnetic materials prepared in Examples 1 to 6 had a purity of 90% or higher.

[0072]

[0073] Measurement of magnetization intensity according to temperature

[0074] For the manganese carbide-based magnetic material prepared in the example, the saturation magnetization was measured under temperature conditions of 5K to 300K. The magnetization intensity of the magnetic material according to temperature was measured using the Vibrating Sample Magnetometer (VSM) function of the Physical Property Measurement System (PPMS®) device from Quantum Design, and the results are shown in Fig. 3 as a Magnetization-Temperature (MT) curve. The magnetic hysteresis curve at 5K was measured using the same equipment.

[0075] FIG. 3 shows the MT curves for the manganese carbide-based magnetic materials of Examples 1 to 6 and the magnetization temperature coefficients (△M / △T) of each example. Referring to FIG. 3, the compositional formula Mn of the manganese carbide-based magnetic material according to the present invention 3+x Ga 1-x It was confirmed that as the x value of C increases, that is, as the Ga ratio decreases, the magnetization temperature coefficient of the manganese carbide-based magnetic material increases, and conversely, as the x value decreases, that is, as the Ga ratio increases, the saturation magnetization strength increases in the temperature range of 5K to 300K.

[0076] FIG. 4 is Example 1 (Mn 3.25 Ga 0.75 This shows the MH graph at a temperature of 5K for the magnetic material of C) and the saturation magnetization intensity measured at temperature conditions of 5K and 300K for the magnetic materials of Examples 1 to 6. Referring to FIG. 4, the compositional formula Mn of the manganese carbide-based magnetic material 3+x Ga 1-x In Example 1, where the x value of C is 0.25, the saturation magnetization decreased as the temperature increased from 5 K to 300 K, and the saturation magnetization was the highest compared to other examples under both 5 K and 300 K temperature conditions. On the other hand, the compositional formula Mn of the manganese carbide-based magnetic material 3+x Ga 1-xExample 6, in which the x value of C is 0.95, showed the lowest saturation magnetization under temperature conditions at 5 K and 300 K, but it was confirmed that the saturation magnetization increased at 300 K compared to 5 K.

[0077] In addition, the magnetization temperature coefficient (△M / △T) measured for the above Examples 1 to 6 and the compositional formula Mn 3+x Ga 1-x To investigate the correlation between the x values ​​of C, △M / △T=ax was determined through computer simulation. b Fitted using the equation of +b.

[0078] As a result of the simulation, a = -0.0107 (95% confidence interval: [-0.0484, 0.0270]), b = -1.7091 (95% confidence interval: [-3.9450, 0.5268]), and c = 0.0722 (95% confidence interval: [-0.0334, 0.0722]), the Sum of Squared Errors (SSE), coefficient of determination (R²), Degrees of Freedom for Error (DFE), Adjusted R², and Root Mean Squared Error (RMSE) values ​​of the fitting were 0.0002, 0.9800, 3.0000, 0.9667, and 0.0073, respectively, confirming that the fitting was performed with very high accuracy.

[0079] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

1. Cho Seong-sik Mn 3+x Ga 1-x Manganese carbide magnetic material represented by C (0≤x<1).

2. The manganese carbide magnetic material of claim 1, wherein the manganese carbide magnetic material has a perovskite crystal structure.

3. In Claim 1, The above manganese carbide-based magnetic material comprises an Mn4C-type crystal phase, wherein the fraction of the Mn4C-type crystal phase is 90% to 100%.

4. In Claim 3 The above Mn4C type crystal phase is Mn of the Mn4C crystal structure. I A manganese carbide-based magnetic material in which some of the Mn atoms at the position are substituted with Ga.

5. In Claim 1, The above manganese carbide magnetic material exhibits diffraction peaks of crystal planes (111), (200), (220), (311), and (222), respectively, at 2θ values ​​near 40°, 48°, 69°, 82°, and 88°, respectively, as a result of XRD analysis.

6. The manganese carbide magnetic material of Claim 1, wherein the magnetization temperature coefficient (△M / △T) of the manganese carbide magnetic material satisfies Equation 1: [Mathematical Formula 1] In the above mathematical formula 1, △M / △T is the magnetization temperature coefficient [emu·g -1 ·K -1 ] and, x is the same as x in the above manganese carbide-based magnetic material composition formula, and a = -0.0107 (95% confidence interval: [-0.0484, 0.0270]), b = -1.7091 (95% confidence interval: [-3.9450, 0.5268]), c = 0.0722 (95% confidence interval: [-0.0334, 0.0722]).

7. In Claim 1, the saturation magnetization (M) of the manganese carbide-based magnetic material at a temperature of 5 K s ) is a manganese carbide-based magnetic material satisfying mathematical formula 2: [Mathematical Formula 2] In the above mathematical formula 2, x is the same as x in the above manganese carbide-based magnetic material composition formula, 107≤a1≤119, and -120≤b1≤-102.

8. In Claim 1, the saturation magnetization (M) of the manganese carbide-based magnetic material at a temperature of 300 K s ) is a manganese carbide-based magnetic material satisfying mathematical formula 3: [Mathematical Formula 3] In the above mathematical formula 3, x is the same as x in the above manganese carbide-based magnetic material composition formula, 86≤a2≤92, and -84≤b2≤-78.

9. The manganese carbide magnetic material of Claim 1, wherein the magnetization temperature coefficient (△M / △T) of the manganese carbide magnetic material is 0 or more and 0.5 or less.

10. The manganese carbide magnetic material of claim 1, wherein the saturation magnetization intensity at 300 K of the manganese carbide magnetic material is 50 emu / g or more and 200 emu / g or less.

11. A method for manufacturing a manganese carbide-based magnetic material according to Claim 1, A step of melting manganese, gallium, and carbonaceous compounds together; and A method for manufacturing a manganese carbide-based magnetic material comprising the step of manufacturing an ingot by cooling a melt of the above manganese, gallium, and carbon-based compounds.

12. In Claim 11, A method for manufacturing a manganese carbide-based magnetic material in which the step of melting the above manganese, gallium, and carbon-based compounds together is performed by induction heating.

13. In Claim 12, A method for manufacturing a manganese carbide-based magnetic material, wherein the above-mentioned induction heating is performed at a temperature of 1000 to 3500 ℃.

Images