Mnbi-based magnet

Abstract

A magnetic body according to an embodiment of the present invention comprises a magnet comprising, on the basis of 100 at% of all elements thereof, manganese (Mn), bismuth (Bi) and ruthenium (Ru) elements, wherein the amount of the manganese (Mn) element is 35-65 at%, the amount of the bismuth (Bi) element is 35-65 at%, the amount of the ruthenium (Ru) element is 2-10 at%, and the magnet may further comprise inevitable impurities.

Description

MnBi-based magnets

[0001] The embodiments relate to a magnetic material and an actuator containing the same. More specifically, the magnetic material relates to an MnBi-based magnet.

[0002] The strongest magnet currently used industrially is the neodymium magnet (Nd-Fe-B). The neodymium magnet is applied in HDDs, speakers, mobile phones, automobiles, or robots. The coercivity of the neodymium magnet decreases as the temperature rises. Accordingly, dysprosium (Dy) is added to the neodymium magnet for use. As a result, the neodymium magnet can maintain high coercivity even at high temperatures. However, dysprosium is an expensive material. Accordingly, there is a demand for permanent magnet materials that can replace the neodymium magnet without the addition of rare earth elements.

[0003] MnBi-based magnets are permanent magnet materials that do not contain rare earth elements. However, MnBi-based magnets have a problem in that their coercivity decreases as the temperature decreases. For example, the decrease rate of magnetic anisotropy energy and coercivity from room temperature of about 23°C to -40°C is more than 30%, which is a problem in that the decrease rate is large.

[0004] Therefore, MnBi-based magnets with low magnetic anisotropy energy reduction and coercivity reduction rates are required even in low-temperature ranges.

[0005]

[0006] Prior art related to the above MnBi-based magnet is disclosed in Korean registered patent (KR10-1585478).

[0007] One of the technical problems of the present invention is to provide an MnBi-based magnet having improved magnetic properties even in a low-temperature range.

[0008] In addition, the present invention can provide an excellent magnetic material that suppresses performance degradation at low temperatures when Mn is 35 at% to 65 at%, Bi is 35 at% to 65 at%, Ru is 1 at% to 10 at%, and the remainder is unavoidable impurities.

[0009] The magnetic material according to an embodiment of the present invention comprises a magnet having manganese (Mn) element, bismuth (Bi) element, and ruthenium (Ru) element when the total at% is 100 at%, wherein the manganese (Mn) element has a range of 35 at% to 65 at%, the bismuth (Bi) element has a range of 35 at% to 65 at%, and the ruthenium (Ru) element has a range of 2 at% to 10 at%, and the magnet may further include unavoidable impurities.

[0010] In addition, the above ruthenium (Ru) element may contain 2 at% to 8 at%.

[0011] In addition, the above ruthenium (Ru) element may contain 4 at% to 8 at%.

[0012] In addition, the reduction rate of coercivity from 300K to 233K can be 60% or less.

[0013] In addition, the rate of reduction in magnetic anisotropy energy from 300K to 233K can be 30% or less.

[0014] In addition, the ruthenium (Ru) element may be included in at least one of the manganese (Mn) phase, the bismuth (Bi) phase, and the MnBi phase.

[0015] A method for manufacturing a magnetic body according to an embodiment of the present invention may include the steps of: melting a raw material of the magnetic body to produce a ribbon, an ingot, or atomized powder; grinding the ribbon, ingot, or atomized powder to produce a powder; separating the powder by a magnetic field; and mixing the powder with a curable resin.

[0016] In addition, the actuator according to an embodiment of the present invention may include any one of the magnetic materials.

[0017] The magnetic material according to an embodiment of the invention can reduce performance degradation from room temperature to low temperature by adding ruthenium (Ru).

[0018] In addition, the reduction rate of magnetic anisotropy energy and coercivity can be significantly reduced from room temperature 300K to 233K by adding ruthenium (Ru).

[0019] In addition, the magnetic material of the example has a coercivity reduction rate (1-Hc) from 300K to 233K. 233K / Hc 300K ) can be reduced to 60% or less.

[0020] Figure 1 is a graph showing the temperature dependence of the lattice constant and the temperature dependence of the magnetic anisotropy energy of an MnBi magnet.

[0021] Figure 2 is a graph comparing experimental and theoretical data on the temperature change of the magnetic anisotropy energy of an MnBi magnet.

[0022] Figure 3 is a schematic diagram showing a method for synthesizing a magnetic material.

[0023] Figure 4 shows the results of magnetization measurements in the hard axis direction of Comparative Example 1.

[0024] Figure 5 shows the magnetization measurement results in the Easy axis direction of Comparative Example 1.

[0025] Figure 6 shows the results of SEM-WDS measurements of Comparative Example 2 after annealing.

[0026] Figure 7 shows the result of measuring the annealing of Example 1 using SEM-WDS.

[0027] Figure 8 is a graph of the X-ray diffraction patterns of the comparative example and the example.

[0028] FIG. 9 shows a cross-sectional view of an actuator including a magnetic body according to an embodiment of the present invention.

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0030] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a sense that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0031]

[0032] Magnetic material (MnBi-based magnet)

[0033] The magnetic body according to the embodiment is (MnBi) a M b It is composed of. Specifically, the magnetic material is formed by substituting or adding an M element to an MnBi magnet. The added M element substitutes at least one of manganese or bismuth, a and b are positive, and the composition formula: a > b is satisfied.

[0034] The magnetic material may contain 35 at% to 65 at% of manganese elements and 35 at% to 65 at% of bismuth elements. Specifically, the MnBi magnet may contain 45 at% to 65 at% of manganese elements and 35 at% to 55 at% of bismuth elements. Additionally, the at% of manganese elements in the MnBi magnet may be greater than the at% of bismuth elements. The at% of manganese elements and bismuth elements is based on the total at% of MnBi being 100 at%.

[0035] The above magnetic material may contain an M element within a set range. Specifically, (MnBi) a M b The magnetic body having the composition may contain M element in an amount greater than 0 at% and less than or equal to 10 at%. More specifically, the magnetic body may contain M element in an amount greater than 0 at% and less than or equal to 8 at%. More specifically, the magnetic body may contain M element in an amount greater than 0 at% and less than or equal to 6 at%. The at% of the M element is (MnBi) a M b It is based on the assumption that the total at% of the atoms is 100 at%. For example, the above M element may include zirconium (Zr), iron (Fe), gallium (Ga), vanadium (V), niobium (Nb), molybdenum (Mo), titanium (Ti), tantalum (Ta), palladium (Pd), ruthenium (Ru), and silicon (Si).

[0036]

[0037] Substitution or addition element crystals of magnetic materials

[0038] Figure 1 is a graph showing the temperature dependence of the lattice constant and magnetic anisotropy energy of an MnBi magnet, and Figure 2 is a graph comparing experimental and theoretical data on the temperature change of the magnetic anisotropy energy of an MnBi magnet.

[0039] Referring to Figures 1 and 2, the spin rearrangement temperature of MnBi is about 100K, and as the temperature increases from about 100K, the magnetic anisotropy energy of MnBi is enhanced.

[0040] More specifically, MnBi can have a hexagonal crystal system structure, and its magnetic properties are characterized by two axes. These two axes are the c-axis (interlayer distance), which represents the direction perpendicular to the basal plane, and the a-axis (in-plane atomic alignment), which represents the direction within the basal plane. In the crystal structure of MnBi, the c-axis is the direction where spin-orbit coupling acts strongly, making it easier for magnetization to align stably. In other words, the c-axis represents the Easy axis. On the other hand, the a-axis represents the direction within the basal plane; since the magnetic anisotropy energy is low and spin alignment is relatively unstable in this direction, more energy is required to align the magnetization in this direction, thus representing the Hard axis.

[0041] When the MnBi lattice stretches with temperature, the c-axis increases the stability of spin alignment, thereby increasing the magnetic anisotropy energy. As the temperature of MnBi rises, both the c-axis and the a-axis stretch due to lattice expansion; however, since the c-axis stretches more than the a-axis, c / a increases, which in turn can cause the magnetic anisotropy energy to increase with temperature. Furthermore, the increase in the magnetic anisotropy energy of MnBi with rising temperature can lead to an increase in the coercivity of MnBi.

[0042] On the other hand, the magnetic anisotropy energy and coercivity of MnBi may decrease with decreasing temperature from 300K to 100K. That is, the magnetic anisotropy energy or coercivity decreases significantly from 300K to 233K, which can degrade the performance of products containing MnBi magnets at low temperatures.

[0043] To address this, the present invention provides an optimal element and ratio capable of suppressing temperature changes in lattice constants, magnetic anisotropy energy, and coercivity by substituting an M element with a small coefficient of thermal expansion into MnBi.

[0044]

[0045] First of all, the thermal expansion coefficient of manganese is 22×10 -6 / K, the coefficient of thermal expansion of bismuth is 13×10 -6 Since / K, the case of substituting manganese is 22×10 -6 For / K or less, in the case of bismuth substitution, 13×10 -6 You just need to substitute an element with a coefficient of thermal expansion of / K or less.

[0046] For example, the above-mentioned substituent element M may include Si, Fe, V, Nb, Mo, Ti, Zr, Ta, Ru, Pd, etc., which are elements with a coefficient of thermal expansion smaller than that of manganese (Mn) and bismuth (Bi).

[0047]

[0048] Composition Saturation Magnetization [emu / g] Anisotropic Magnetic Field [Oe] MAE [MJ / m 3]300K~233K MAE reduction rate Coercivity [Oe]300K~233K Coercivity Reduction Rate 233K 300K 233K 300K 233K 300K 233K 300K Comparative Example 1 Mn 55Bi 45 6 2.36 0.13 30 535 0 50 8 0.92 1.36 3 2.2% 88 7.32 429.76 3.5% Comparative Example 2 Mn 49Bi 49Si 2 6.16 2.93 30 92 49 85 2 0.98 1.41 3 0.2% 10 7 2.32 90 6.36 3.1% Comparative Example 3 Mn 48Bi 48Si 4 39.53 7.93 30 768 45 66 6 0.54 0.77 29.8% 34 9.916 15.87 8.3% Comparative Example 4 Mn 49Bi 49Fe 23 2.3 29.730740445990.440.5925.2%372.41933.980.7%Comparative Example 5Mn48Bi48Fe440.538.330249446990.550.7728.4%379.61833.679.3%Comparative Example 6Mn47.5Bi47.5Ga555.853.733168500720.831.2131.1%1068.12993.464.3%Comparative Example 7Mn49Bi49V268.164.532819482061.001.3928.1%1072.62927.663.4%Comparative Example 8M n48Bi48V463.960.232941494870.941.3429.4%1012.13105.767.4%Comparative Example 9Mn49Bi49Nb263.360.332659476160.931.2927.9%1269.03629.365.0%Comparative Example 10Mn48Bi48Nb462.659.132525483880.911.2828.8%1287.64083.268.5%Comparative Example 11Mn49Bi49Mo268.064.732099490570.981.4231.2%1128.231 79.564.5% Comparative Example 12Mn48Bi48Mo463.261.133425503920.951.3831.4%1054.93288.167.9% Comparative Example 13Mn49Bi49Ti269.265.732692485171.011.4329.0%1175.13473.166.2% Comparative Example 14Mn48Bi48Ti477.073.233339512291.151.731.6%993.23387.670.7% Comparative Example 15Mn49Bi49Zr267.263.632395486810.971.3929.7%1077.63316.867.5%Comparative Example 16Mn48Bi48Zr463.560.23286450968.920.941.432.0%901.72986.41369.8%Comparative Example 17Mn49Bi49Ta261.958.732731490300.911.2929.6%1082.23085.164.9%Comparative Example 18Mn48Bi48Ta458.15531894 48549.570.831.230.2%850.62712.3168.6%Comparative Example 19Mn49Bi49Zn262.158.833613500460.931.3229.2%1048.72912.864.0%Comparative Example 20Mn49Bi49In240.5393282649651.410.600.930.9%1077.94005.36673.1%Comparative Example 21Mn48Bi48In4 47.2453213147746.090.681.029.5%934.44052.66376.9%Comparative Example 22Mn49Bi49Pd241.036.929089436210.520.7126.1%1673.35591.770.1%Example 1Mn49Bi49Ru260.456.731878467940.861.1927.5%1512.33254.753.5%Example 2Mn4 8Bi48Ru440.436.538512506150.700.8315.8%3058.34493.731.9%Example 3Mn47Bi47Ru633.230.037990518110.560.6918.9%3007.94374.631.2%Example 4Mn46Bi46Ru825.222.143582555140.490.5410.4%3638.44059.210.4%.

[0049] [Table 1] shows the saturation magnetization, anisotropic magnetic field, magnetic anisotropic energy, MAE reduction rate from 300K to 233K, coercivity, and coercivity reduction rate from 300K to 233K when zirconium (Zr), iron (Fe), gallium (Ga), vanadium (V), niobium (Nb), molybdenum (Mo), titanium (Ti), tantalum (Ta), palladium (Pd), ruthenium (Ru), and silicon (Si) are substituted into MnBi magnets.

[0050]

[0051] Figure 3 is a schematic diagram showing a method for synthesizing a magnetic material.

[0052] Referring to FIG. 3, first, the raw material is heated and melted in a ceramic crucible in an Ar atmosphere at approximately 1200°C (S1). Subsequently, the molten metal is transferred to a metal mold to produce an ingot, ribbon, or atomized powder, and this ingot, ribbon, or atomized powder is homogenized by annealing it for 48 hours in a temperature range of 280-320°C (S2). Afterward, the annealed ingot, ribbon, or atomized powder is crushed to form a powder (S3). The crushed powder is separated by a magnetic field to remove impurities and increase the purity of the magnetic material particles (S4). Subsequently, the particle size of the magnetic material is uniformly classified through sieving to ensure an optimal particle distribution (S5). Finally, the classified powdered magnetic material is mixed with a curable resin and cured in a magnetic field to produce a sample with orientation (S6).

[0053]

[0054] Figure 4 shows the results of magnetization measurements in the Hard axis direction of Comparative Example 1, and Figure 5 shows the results of magnetization measurements in the Easy axis direction of Comparative Example 1.

[0055] [Comparative Example 1]

[0056] Referring to FIGS. 4 and 5, Comparative Example 1 is formed by combining Mn and Bi in the ratio of Mn: 55 at% and Bi: 45 at% as an MnBi magnet. Here, the magnetization of the sample of Comparative Example 1 in the direction of the hard axis is measured.

[0057] In Comparative Example 1, the anisotropic magnetic field at 223 K was defined as the intersection of a linear approximation line from 0 to 30 kOe and a linear approximation line from 80 to 90 kOe, and the anisotropic magnetic field at 300 K was defined as the intersection of a linear approximation line from 0 to 50 kOe and a linear approximation line from 80 to 90 kOe. Referring to [Table 1], the anisotropic magnetic fields at 233 K and 300 K of Comparative Example 1 are measured as 33053 Oe and 50508 Oe, respectively. The saturation magnetization at 233 K and 300 K of Comparative Example 1 is measured as 62.3 emu / g and 60.1 emu / g, respectively.

[0058] The magnetic anisotropy energy is calculated using Equation 1 below, and the magnetic anisotropy energies MAE at 233K and 300K of Comparative Example 1 233K and MAE 300K 0.92 MJ / m² respectively 3 and 1.36 MJ / m² 3 It is measured as.

[0059] Equation 1: Magnetic Anisotropy Energy = (Anisotropic Magnetic Field) x (Saturation Magnetization) / 2

[0060]

[0061] The magnetic anisotropy energy reduction rate is calculated using Equation 2 below, and the magnetic anisotropy energy reduction rate from 300K to 233K in Comparative Example 1 is calculated to be 32.2%.

[0062] Equation 2: Magnetic Anisotropy Energy Decrease Rate = 1 - (MAE 233K / MAE 300K )

[0063]

[0064] The coercivity was calculated by performing magnetization measurements on the above-mentioned oriented sample at -10 to 50 kOe along the easy-to-magnetize axis. In Fig. 4, the magnetic field at which the magnetization in the second quadrant is 0 emu / g is defined as the coercivity. The coercivity Hc of Comparative Example 1 at 233 K and 300 K. 233K and Hc 300KThe values ​​are calculated to be 887.3 Oe and 2429.7 Oe, respectively. At this time, the reduction rate of coercivity from 300K to 233K in Comparative Example 1 is calculated to be 63.5% when calculated based on Equation 3 below.

[0065] Equation 3: Coercivity reduction rate = 1-(Hc 233K / Hc 300K )

[0066]

[0067] In other words, Comparative Example 1 is an MnBi magnet that is not substituted with any element, and it can be seen that the reduction rate of magnetic anisotropy energy and the reduction rate of coercivity in the low and high temperature ranges are large.

[0068]

[0069] [Comparative Example 2]

[0070] Comparative Example 2 is (MnBi) a M b The element M is replaced with the silicon element (Si).

[0071] In Comparative Example 2, Mn: 49at%, Bi: 49at%, Si: 2at% were combined, (MnBi) 49 Si2 was manufactured. Comparative Example 2 was manufactured using the same technique as Comparative Example 1, and each value was calculated.

[0072] The reduction rates of magnetic anisotropy energy and coercivity from 300K to 233K in Comparative Example 2 are 30.2% and 63.1%, respectively, which are measured to be similar to Comparative Example 1.

[0073] Figure 6 shows the results of SEM-WDS measurements of Comparative Example 2 after annealing.

[0074] Generally, MnBi-based magnets cannot exist as 100% MnBi phase. That is, MnBi-based magnets may contain some Bi phase and Mn phase mixed in addition to the MnBi phase. In addition, silicon (Si) elements are presumed to be present in the MnBi phase, Bi phase, Mn phase, and at the boundaries between each phase.

[0075] In Comparative Example 2, judging by the occurrence of cracks, it is presumed that Si is hardly dissolved in the MnBi magnetic phase; consequently, it is expected that the effect of suppressing the change in thermal expansion of MnBi does not appear, and the reduction rate of magnetic anisotropy energy and coercivity does not decrease. In other words, (MnBi) a M b For the effect of thermal expansion of MnBi-based magnets to be reduced at low temperatures of 233K, the reduction rate of magnetic anisotropy energy and the reduction rate of coercivity can be lowered. In other words, to reduce the reduction rate of magnetic anisotropy energy and the reduction rate of coercivity, it is important to substitute an element that has a lower coefficient of thermal expansion than Mn and Bi and is dissolved in the MnBi magnetic phase.

[0076]

[0077] [Example]

[0078] Example 1 is (MnBi) a M b It is in which the element M is replaced with the element ruthenium (Ru).

[0079] Example 1 is composed of Mn: 49at%, Bi: 49at%, and Ru: 2at%, (MnBi) 49 Ru2 was prepared. Example 2 was prepared by combining Mn: 48at%, Bi: 48at%, and Ru: 4at%, (MnBi) 48Ru4 was prepared. Example 3 was prepared by combining Mn: 47at%, Bi: 47at%, and Ru: 6at%, (MnBi) 47 Ru6 was prepared. Example 4 was prepared by combining Mn: 46 at%, Bi: 46 at%, and Ru: 8 at%, (MnBi) 46 Ru8 was manufactured. The example was manufactured using the same method as Comparative Example 1, and each value was calculated.

[0080] It can be seen that the reduction rates of magnetic anisotropy energy and coercivity from 300K to 233K in Example 1 are 27.5% and 53.5%, respectively, which is smaller compared to Comparative Example 1.

[0081] Figure 7 shows the result of measuring the annealing of Example 1 using SEM-WDS.

[0082] In Example 1, not only the MnBi phase but also the Bi phase and Mn phase may exist in a partially mixed manner. In this case, it is presumed that the ruthenium (Ru) element is contained within the MnBi phase, Bi phase, Mn phase, and the boundaries between each phase.

[0083] Referring to Fig. 7, since no cracks occurred in Example 1, it is presumed that the magnetic phase is evenly dissolved at the interfaces of the MnBi phase, Bi phase, Mn phase, and each phase, and thus is less affected by heat. In other words, it is presumed that the ruthenium element, which has a small coefficient of thermal expansion, suppresses the change in thermal expansion of each phase, thereby reducing the reduction rate of magnetic anisotropy energy and coercivity. Furthermore, even considering that the reduction rates of magnetic anisotropy energy and coercivity in Examples 2, 3, and 4, where the content of the ruthenium element is increased, are further reduced, it appears that the content of the ruthenium element influences the reduction rate of magnetic anisotropy energy and coercivity.

[0084]

[0085] Figure 8 is a graph of the X-ray diffraction patterns of the comparative example and the example.

[0086] Figure 8(a) is a graph of the X-ray diffraction patterns of Comparative Example 1, Example 1, Example 2, Example 3, and Example 4, showing the relationship between 2θ (diffraction angle) and intensity. X-rays exhibit diffraction peaks at specific angles, which can provide information on lattice constants, atomic arrangement, and phase.

[0087] In MnBi-based magnets, the MnBi phase may exist in a mixture of partial Bi and Mn phases as well as the MnBi phase. In this case, the MnBi phase can have a Low Temperature Phase (LTP) and a High Temperature Phase (HTP). The low-temperature phase of MnBi has a hexagonal structure, while the high-temperature phase has a tetragonal structure. The wt% of the high-temperature and low-temperature phases of MnBi can be measured from the X-ray diffraction pattern graph.

[0088]

[0089] Referring to [Table 1] and Figures 8(a) and 8(b), Comparative Example 1 has only a low-temperature phase of MnBi, with the low-temperature phase of MnBi being 67.9 wt%, the Mn phase being 6.2 wt%, and the Bi phase being 25.9 wt%. That is, since Comparative Example 1 has a Bi phase content of 25.9 wt%, it can be seen that the proportion of the MnBi phase is somewhat reduced. As a result, a difference in the coefficient of thermal expansion occurs depending on the wt% ratio of the MnBi phase, Bi phase, and Mn phase, which can easily lead to cracking.

[0090] On the other hand, it can be seen that as the ruthenium element content of Examples 1 to 4 increases, the wt% of the high-temperature phase of MnBi increases, while the wt% of the Mn phase and Bi phase decreases. In other words, it is presumed that the occurrence of cracks in MnBi-based magnets decreases as the Mn phase and Bi phase, which have high coefficients of thermal expansion, decrease. Consequently, the rate of reduction in magnetic anisotropy energy and coercivity of MnBi-based magnets may decrease.

[0091]

[0092] FIG. 9 shows a cross-sectional view of an actuator including a magnetic body according to an embodiment of the present invention.

[0093] Referring to FIG. 9, the actuator (10) according to the embodiment may be a voice coil motor (VCM). The actuator (10) includes a housing (100), a bobbin assembly (200) including a bobbin (210) and a coil (220), a leaf spring (300), and a magnet (400).

[0094] The above housing (100) is intended to support the bobbin assembly (200) and may have a housing base portion (110) and a housing body portion (120) having a certain space inside. The housing body portion (120) may include the bobbin assembly (200), a leaf spring (300), a permanent magnet (400), and a spacer (not shown). The housing (100) may include a square column shape, a circular column, a polygonal column, etc., but is not limited thereto.

[0095] The bobbin (210) is movable in a vertical direction, and a coil (220) is wound on its outer surface. This bobbin (210) may be a camera lens holder or a magnetic head, etc. The coil (220) wound on the outer surface of the bobbin (210) forms a magnetic field according to the magnitude and direction of the input current, and can move the bobbin (210) in a vertical direction through attractive and repulsive forces with an adjacent permanent magnet (400).

[0096] The above-mentioned plate spring (300) is coupled to one side of the bobbin (210) to elastically support the vertical movement of the bobbin (210) and may have a metal material having elasticity.

[0097] The magnet (400) may include a magnetic material according to an embodiment of the present invention. Since the magnetic material has a small reduction rate of magnetic anisotropy energy and a reduction rate of coercivity from 300K to 233K, the reliability of the actuator (10) can be improved.

[0098]

[0099] Although the above description has focused on the embodiments, this is merely an example and is not intended to limit the embodiments. A person skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the embodiments. For instance, each component specifically shown in the embodiments may be modified and implemented. Furthermore, differences related to such modifications and applications should be interpreted as being included within the scope of the embodiments set forth in the appended claims.

[0100]

[0101] The MnBi-based magnetic material of the present invention does not contain rare earth elements, yet by adding Ru, it can reduce the reduction rate of magnetic anisotropy energy and coercivity in the range from room temperature (300K) to low temperature (233K), making it applicable to various drive systems where performance degradation in low-temperature environments is a problem. In particular, this magnetic material can be applied as a permanent magnet for actuators such as voice coil motors (VCMs), and in this case, it can improve device reliability by suppressing the decrease in driving force / responsiveness caused by the reduction in coercivity at low temperatures. Therefore, the present invention can be manufactured and used in various industrial fields, such as lens driving devices for camera modules, precision position control actuators, small motors, and electronic and electrical components including sensors and magnets.

Claims

1. When the total at% is set to 100 at%, It includes a magnet having the elements manganese (Mn), bismuth (Bi), and ruthenium (Ru), and The above manganese (Mn) element has a range of 35 at% to 65 at%, and The above bismuth (Bi) element has a range of 35 at% to 65 at%, and The above ruthenium (Ru) element has a range of 2 at% to 10 at%, and The above magnet is a magnetic material containing additional unavoidable impurities.

2. In Paragraph 1, The above ruthenium (Ru) element is a magnetic material containing 2 at% to 8 at%.

3. In Paragraph 1, The above ruthenium (Ru) element is a magnetic material containing 4 at% to 8 at%.

4. In any one of paragraphs 1 to 3, A magnetic material with a coercivity reduction rate of 60% or less from 300K to 233K.

5. In any one of paragraphs 1 to 3, A magnetic material having a magnetic anisotropy energy reduction rate of 30% or less from 300K to 233K.

6. In any one of paragraphs 1 to 3, The above ruthenium (Ru) element is a magnetic material included in at least one of the above manganese (Mn) phase, the above bismuth (Bi) phase, and the MnBi phase.

7. In any one of paragraphs 1 to 3, The above ruthenium element is a magnetic material included at the boundary of the above manganese (Mn) phase, the above bismuth (Bi) phase, and the MnBi phase.

8. In a magnetic material according to any one of paragraphs 1 to 6, A step of melting the raw material of the above magnetic material to produce a ribbon, ingot, or atomized powder; A step of manufacturing powder by grinding the above ribbon, ingot, or atomized powder; Step of magnetic field separation of the above powder; and A method for manufacturing a magnetic material comprising the step of mixing the above powder with a curable resin.

9. In Paragraph 7, A method for manufacturing a magnetic material comprising the step of homogenizing the above ribbon, ingot, or atomized powder by annealing at 280°C to 320°C for 48 hours.

10. An actuator comprising a magnetic material according to any one of claims 1 to 6.

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