sintered body

Abstract

The present invention provides a sintered body having a high Curie point and exhibiting high magnetic permeability in a high frequency region. The sintered body comprises a spinel-type ferrite oxide having a main component of a metal element being Fe, Ni, Cu, and Zn, and further comprises Zr, Mn, Al, Co, and Cr, and when the molar fractions of Zn, Ni, Cu, Zr, Mn, Al, Co, and Cr, with Fe being 100 mol, are respectively set as a, b, c, d, e, f, g, and h, 100-a-b-c+2d+(1 / 2)e, a+b+c+d+e / 2, f, g, and h respectively satisfy the following formulas (1) to (5). 49.0 < 100-a-b-c+2d+(1 / 2)e < 50.0 (1) 50.2 < a+b+c+d+e / 2 < 52.7 (2) 0.0012 ≤ f ≤ 0.010 (3) 0.0005 ≤ g ≤ 0.0015 (4) 0.0005 ≤ h ≤ 0.004 (5).

Description

Technical Field

[0001] This disclosure relates to sintered bodies, and more specifically, to sintered bodies comprising spinel-type ferrite oxides. Background Technology

[0002] In recent years, there has been a demand for miniaturization and high density in electronic devices, leading to increasingly higher operating frequencies. In particular, magnetic materials for power transformers used in the high-frequency region are increasingly employing materials such as Mn-Zn ferrites, which are easily magnetized in low magnetic fields and exhibit low power loss, and Ni-Zn ferrites, which have high resistivity. Patent Document 1 discloses a Ni-Zn ferrite composition with high initial permeability and resistivity that reduces power loss in the high-frequency region. The above-mentioned Ni-Zn ferrite composition contains, as the main component, 47.1 to 49.95 mol% iron oxide (equivalent to Fe2O3), 2.3 to 10.0 mol% copper oxide (equivalent to CuO), 27.6 to 32.0 mol% zinc oxide (equivalent to ZnO), and 0.01 to 2.1 mol% manganese oxide (equivalent to Mn2O3). The remainder is composed of nickel oxide. As a secondary component relative to 100 parts by mass of the above-mentioned main component, it contains 2 to 63 ppm phosphorus (equivalent to P), 43 to 4530 ppm zirconium oxide (equivalent to ZrO2), and 0.01 to 0.15 parts by mass of molybdenum oxide (equivalent to MoO3).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-96961 Summary of the Invention

[0006] In recent years, there has been a demand for magnetic materials with high Curie points (Tc) and higher permeability in high-frequency regions, such as above 100 kHz. However, the Ni-Zn ferrite composition of Patent Document 1 is difficult to achieve this property and requires further improvement. This disclosure is made in view of the above situation, and its object is to provide a sintered body with a high Curie point and high permeability in the high-frequency region.

[0007] According to one aspect of the present invention,

[0008] A sintered body is provided, comprising a spinel-type ferrite oxide with Fe, Ni, Cu, and Zn as its main metallic elements.

[0009] It also contains Zr, Mn, Al, Co, and Cr.

[0010] When the molar contents of Zn, Ni, Cu, Zr, Mn, Al, Co, and Cr are a, b, c, d, e, f, g, and h respectively when Fe is 100 molar parts, 100-a-b-c+2d+(1 / 2)e, a+b+c+d+e / 2, f, g, and h respectively satisfy the following equations (1) to (5).

[0011] 49.0<100-a-b-c+2d+(1 / 2)e<50.0···(1)

[0012] 50.2<a+b+c+d+e / 2<52.7···(2)

[0013] 0.0012≤f≤0.010···(3)

[0014] 0.0005≤g≤0.0015···(4)

[0015] 0.0005≤h≤0.004···(5)

[0016] In one embodiment of the present invention, in the sintered body described above, d satisfies the following formula (6) and e satisfies the following formula (7).

[0017] 0.10≤d≤0.50···(6)

[0018] 0.055≤e≤0.25···(7)

[0019] According to this disclosure, sintered bodies with high Curie points and high permeability in the high-frequency region can be provided. Attached Figure Description

[0020] Figure 1 It represents the reflected electron image of the cross-section of the sintered body and the microscopic photograph of the Cu distribution observed using SEM-WDX (Scanning Electron Microscope-Wavelength Dispersive X-ray spectroscopy). Detailed Implementation

[0021] The sintered body of this embodiment comprises spinel-type ferrite oxides whose main metallic elements are Fe, Ni, Cu and Zn.

[0022] Further includes Zr, Mn, Al, Co, and Cr.

[0023] When the molar contents of Zn, Ni, Cu, Zr, Mn, Al, Co, and Cr are a, b, c, d, e, f, g, and h respectively when Fe is 100 molar parts, 100-a-b-c+2d+(1 / 2)e, a+b+c+d+e / 2, f, g, and h respectively satisfy the following equations (1) to (5).

[0024] 49.0<100-a-b-c+2d+(1 / 2)e<50.0···(1)

[0025] 50.2<a+b+c+d+e / 2<52.7···(2)

[0026] 0.0012≤f≤0.010···(3)

[0027] 0.0005≤g≤0.0015···(4)

[0028] 0.0005≤h≤0.004···(5)

[0029] The spinel-type ferrite oxide contained in the sintered body of this embodiment contains Fe, Ni, Cu, and Zn as the main metallic elements. In this specification, "main component" refers to 50 mol% or more. The proportion of Fe, Ni, Cu, and Zn among all the metallic elements contained in the aforementioned spinel-type ferrite oxide can be 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more.

[0030] The content of each of the metal elements in the main components mentioned above is not particularly limited. For example, when the molar contents of Zn, Ni, and Cu are set as a, b, and c respectively when Fe is 100 molar parts, a, b, and c are all greater than 0, and a can be in the range of 23.9 to 34.6. b can be in the range of 6.7 to 27.0. c can be in the range of 0.1 to 10.2.

[0031] The sintered body of this embodiment comprises the aforementioned spinel-type ferrite oxide. The proportion of spinel-type ferrite oxide in the sintered body of this embodiment is preferably 90% by mass or more, more preferably 95% by mass or more. In the sintered body of this embodiment, the proportion of spinel-type ferrite oxide can substantially be 100% by mass, that is, it is formed from spinel-type ferrite oxide. The sintered body of this embodiment may, for example, contain unavoidable impurities such as carbon and sulfur from the binder used during manufacturing, within a range of, for example, a total of 5% by mass or less, and further, a total of 1% by mass or less.

[0032] The sintered body of this embodiment further comprises Zr, Mn, Al, Co, and Cr. The molar contents of Fe, Ni, Cu, and Zn, and the contents of these elements, expressed as a, b, c, d, e, f, g, and h, satisfy all of the above equations (1) to (5). These equations will be explained below.

[0033] In this embodiment, it was found that by setting the total stoichiometry (mol%) of Fe2O3, Mn2O3, and (3 / 2)ZrO2 in the sintered body, i.e., [Fe2O3+Mn2O3+(3 / 2)ZrO2], within a specified range, and by strictly controlling the contents of Al, Co, and Cr within the above range, the permeability (μ') in the high-frequency region was significantly improved (hereinafter, the realization of high μ' is sometimes referred to as "high μ'ization"). First, the high μ'ization in the high-frequency region achieved by controlling [Fe2O3+Mn2O3+(3 / 2)ZrO2] will be explained.

[0034] [High μ' in the high-frequency region is achieved by controlling [Fe2O3+Mn2O3+(3 / 2)ZrO2]]

[0035] Spinel-type ferrite oxides are represented as AO·B₂O₃ (A: divalent ion, B: trivalent ion). When the amount of trivalent ions constituting the above oxides becomes excessive, Fe… 3+ Part of it becomes Fe 2+ For charge compensation, the permeability (μ') in the high-frequency region decreases. Furthermore, in spinel-type ferrite oxides with Fe-Ni-Cu-Zn as the main component, Mn can also exist in the trivalent state. Therefore, conventionally, as a means to improve permeability, the amounts of Fe and Mn capable of forming trivalent ions are suppressed to below a specified amount. However, in this invention, a detailed investigation was conducted on the relationship between the composition of spinel-type ferrite oxides with Fe-Ni-Cu-Zn as the main component and charge compensation, and it was found that Zr... 4+ This also contributes to the study. Therefore, [Fe2O3+Mn2O3+(3 / 2)ZrO2] was identified as an index that also includes Zr, and this index was applied to the design of the composition. The results showed that it was correlated with μ' in the high-frequency region and could reliably improve μ' in the high-frequency region.

[0036] In this invention, the molar contents of Zn, Ni, Cu, Zr, and Mn when Fe is 100 molar parts are respectively set as a, b, c, d, and e, and [Fe2O3+Mn2O3+(3 / 2)ZrO2] is controlled by [100-a-b-c+2d+(1 / 2)e] (hereinafter sometimes referred to as "α value"), which is expressed in terms of the molar contents of the above elements. First, the method of transforming [Fe2O3+Mn2O3+(3 / 2)ZrO2] into [100-a-b-c+2d+(1 / 2)e], which is expressed in terms of the molar contents of the above elements, will be described.

[0037] The Fe, Ni, Zn, Cu, Mn, and Zr contained in the spinel-type ferrite oxide of this embodiment are converted into oxides (Fe₂O₃, NiO, ZnO, CuO, Mn₂O₃, ZrO₂). Then, when the sum is set to 100 molar parts, the sintered body of this embodiment can reliably improve μ' in the high-frequency region by satisfying the above-mentioned content of Fe₂O₃, Mn₂O₃, and ZrO₂. The reason for setting this range will be explained in detail later.

[0038] 49.50<[Fe2O3+Mn2O3+(3 / 2)ZrO2]<50.00···(1a)

[0039] The above equation (1a) is divided into the following equation (1b) and the following equation (1c).

[0040] 49.50<[Fe2O3+Mn2O3+(3 / 2)ZrO2]···(1b)

[0041] [Fe2O3+Mn2O3+(3 / 2)ZrO2]<50.00···(1c)

[0042] When the molar contents of Zn, Ni, Cu, Zr, and Mn when Fe is 100 molar parts are set as a, b, c, d, and e respectively, the molar percentages of Fe2O3, ZrO2, and Mn2O3 are represented by a, b, c, d, and e respectively, as shown in equations (1d), (1e), and (1f) below.

[0043] Fe2O3={50 / (50+a+b+c+d+e / 2)}×100···(1d)

[0044] ZrO2={d / (50+a+b+c+d+e / 2)}×100···(1e)

[0045] Mn2O3={(e / 2) / (50+a+b+c+d+e / 2)}×100···(1f)

[0046] Substituting equations (1d), (1e), and (1f) into equation (1b), equation (1g) is calculated as follows.

[0047] 49.50<{(50+(3 / 2)d+e / 2) / (50+a+b+c+d+e / 2)}×100

[0048] 50+a+b+c+d+e / 2<(50+(3 / 2)d+e / 2)×2.02

[0049] 50+a+b+c+d+e / 2<101+3.03d+1.01e

[0050] 49.0<100-a-b-c+2.03d+0.51e···(1g)

[0051] In equation (1g), if we set 2.03≈2 and 0.51≈1 / 2, we get equation (1h).

[0052] 49.0<100-a-b-c-2d+e / 2···(1h)

[0053] Substituting equation (1c) into equations (1d), (1e), and (1f) above, equation (1i) is calculated as follows.

[0054] {(50+(3 / 2)d+e / 2) / (50+a+b+c+d+e / 2)}×100<50.00

[0055] 100 + 3d + e < 50.0 + a + b + c + d + e / 2

[0056] 100-a-b-c+2d+e / 2<50.0···(1i)

[0057] Combining equation (1h) with equation (1i), we obtain equation (1). It should be noted that a, b, c, d, and e are all greater than 0.

[0058] 49.0<100-a-b-c+2d+(1 / 2)e<50.0···(1)

[0059] When the amount (mol%) of [Fe2O3+Mn2O3+(3 / 2)ZrO2] is too small, the oxygen vacancies in spinel-type ferrite oxides increase. To address this issue, CuO tends to escape from the spinel crystals during sintering, resulting in increased CuO segregation and a decrease in μ' in the high-frequency region. Therefore, by increasing the amount of [Fe2O3+Mn2O3+(3 / 2)ZrO2], the oxygen vacancies can be reduced, and the μ' in the high-frequency region can be increased. Based on these considerations, [100-a-b-c+2d+(1 / 2)e] should exceed 49.0. [100-a-b-c+2d+(1 / 2)e] can be above 49.5.

[0060] By increasing the aforementioned [100-a-b-c+2d+(1 / 2)e], it is easy to achieve high μ' in the high-frequency region. On the other hand, when the aforementioned [100-a-b-c+2d+(1 / 2)e] is 50 or higher, Fe 3+ Part of it becomes Fe 2+ Used for charge compensation, producing Fe 3+ with Fe 2+ The jump conduction between these points becomes the starting point and generates relaxation loss, thus reducing μ' in the high-frequency region. Therefore, [100-a-b-c+2d+(1 / 2)e] is less than 50.0. [100-a-b-c+2d+(1 / 2)e] can be below 49.8.

[0061] As shown in the prior art, even when the combined stoichiometry of Fe2O3 and Mn2O3 is less than about 50 mol%, it is difficult to reliably increase μ' in the high-frequency region. According to the present invention, it has been found that by making [Fe2O3+Mn2O3+(3 / 2)ZrO2] particularly less than 50.00 mol%, i.e., satisfying 100-a-b-c+2d+(1 / 2)e<50.0, the decrease in μ' in the high-frequency region due to relaxation loss can be reliably suppressed.

[0062] In addition to the aforementioned α value, specifying the amount of Fe2O3 is also important for achieving high μ' in the high-frequency region. The following explains how to achieve high μ' in the high-frequency region by controlling the amount of Fe2O3.

[0063] [High μ' in the high-frequency region is achieved by controlling the amount of Fe2O3]

[0064] By controlling the amount of Fe2O3 in the sintered body of this embodiment, μ' can be reliably increased in the high-frequency region. In this invention, the amount of Fe2O3 (mol%) is controlled using [a+b+c+d+e / 2] (hereinafter sometimes referred to as "β value"), expressed in molar parts of each element, similar to the α value described above. First, the method for converting the amount of Fe2O3 into [a+b+c+d+e / 2], expressed in molar parts of each element, will be described.

[0065] The Fe, Ni, Zn, Cu, Mn, and Zr contained in the spinel-type ferrite oxide of this embodiment are converted into oxides (Fe2O3, NiO, ZnO, CuO, Mn2O3, ZrO2). Then, when the total amount is set to 100 molar parts, the content of Fe2O3 in the spinel-type ferrite oxide of this embodiment satisfies the following range, which can reliably improve μ' in the high-frequency region.

[0066] 48.67<Fe2O3<49.91···(2a)

[0067] The above equation (2a) can be divided into the following equations (2b) and (2c).

[0068] 48.67 < Fe2O3···(2b)

[0069] Fe2O3<49.91···(2c)

[0070] When the molar contents of Zn, Ni, Cu, Zr, and Mn are set as a, b, c, d, and e respectively when Fe is 100 molar parts, Fe2O3 uses a, b, c, d, and e as shown in the following formula (2d).

[0071] Fe2O3=50 / (50+a+b+c+d+e / 2)×100···(2d)

[0072] Substituting equation (2b) into equation (2d) above, we can calculate equation (2e) as follows.

[0073] 48.67<{50 / (50+a+b+c+d+e / 2)}×100

[0074] 50 + a + b + c + d + e / 2 < 5000 / 48.67

[0075] a + b + c + d + e / 2 < 52.7···(2e)

[0076] Substituting equation (2c) into equation (2d) above, we can calculate equation (2f) as follows.

[0077] {50 / (50+a+b+c+d+e / 2)}×100<49.91

[0078] 5000 / 49.91 < 50 + a + b + c + d + e / 2

[0079] 50.2 < a + b + c + d + e / 2···(2f)

[0080] Combining equation (2e) with equation (2f), we obtain equation (2). It should be noted that a, b, c, d, and e all exceed 0.

[0081] 50.2 < a + b + c + d + e / 2 < 52.7 (2)

[0082] By making [a+b+c+d+e / 2], representing the amount of Fe2O3, greater than 50.2 and less than 52.7, μ' in the high-frequency region can be reliably improved. [a+b+c+d+e / 2] can be 50.4 or more. Alternatively, [a+b+c+d+e / 2] can be 52.0 or less.

[0083] In this embodiment, the sintered body contains [Fe2O3+Mn2O3+(3 / 2)ZrO2] and Fe2O3 within a specified range, and the molar contents f, g, and h of Al, Co, and Cr are strictly controlled within the following ranges.

[0084] 0.0012≤f≤0.010···(3)

[0085] 0.0005≤g≤0.0015···(4)

[0086] 0.0005≤h≤0.004···(5)

[0087] By limiting the contents of Al, Co, and Cr within the ranges specified above, as in the examples described later. Figure 1As shown, Cu segregation can be suppressed, and high μ' in the high-frequency region can be achieved. The reason for suppressing Cu segregation by strictly controlling the contents of Al, Co, and Cr is as follows. Since Al, Co, and Cr are elements that are difficult to dissolve in spinel, it is speculated that if they are included in excess, they will combine with Cu, which is a component of the liquid phase, to form precipitates as impurities, thereby causing Cu segregation. By suppressing the amounts f, g, and h of Al, Co, and Cr to 0.010 or less, 0.0015 or less, and 0.004 or less, respectively, Cu segregation is suppressed, and high μ' in the high-frequency region can be achieved. Al(f) is preferably 0.005 or less, more preferably 0.003 or less. Co(g) is preferably 0.0010 or less, more preferably 0.0008 or less. Cr(h) is preferably 0.0030 or less, more preferably 0.0015 or less. Since Cu segregation tends to form in the range of [Fe2O3+Mn2O3+(3 / 2)ZrO2] in the sintered body of the present invention, i.e., at a relatively high value of [Fe2O3+Mn2O3+(3 / 2)ZrO2], it is particularly important to strictly control the contents of Al, Co, and Cr. On the other hand, when the contents of Al, Co, and Cr in the sintered body are too low, it is difficult to form a liquid phase component, resulting in reduced sinterability, and therefore it is speculated that μ' in the high-frequency region will decrease. Therefore, Al(f) is set to 0.0012 or more, and Co(g) and Cr(h) are set to 0.0005 or more. Al(f) is preferably 0.0015 or more, more preferably 0.0020 or more. Co(g) is preferably 0.0006 or more, more preferably 0.0007 or more. Cr(h) is preferably 0.0007 or more, more preferably 0.0010 or more.

[0088] According to the present invention, by keeping the amounts of [Fe2O3+Mn2O3+(3 / 2)ZrO2] and Fe2O3 within a specified range, and by strictly controlling the amounts of Al, Co and Cr to extremely small amounts, which is not done in the prior art, μ' in the high-frequency region can be improved more reliably.

[0089] The sintered body of this embodiment, for example, contains Fe, Ni, Cu, Zn, Zr, Mn, Al, Co, and Cr as a composite oxide. The sintered body of this embodiment can be a composite oxide of Fe, Ni, Cu, Zn, Zr, Mn, Al, Co, and Cr. As described above, the sintered body of this embodiment may contain unavoidable impurities.

[0090] In the sintered body of this embodiment, it is further preferred that the above-mentioned d representing the amount of Zr satisfies the following formula (6) and the above-mentioned e representing the amount of Mn satisfies the following formula (7).

[0091] 0.10≤d≤0.50···(6)

[0092] 0.055≤e≤0.25···(7)

[0093] By ensuring that the Mn amount (e) is within a specified range, and then including ZrO2 to ensure that the Zr amount (d) is within the aforementioned range, it is possible to further improve μ' in the high-frequency region. This is believed to be because by adding a specified amount of Zr while ensuring that the Mn amount (e) is within the specified range, magnetic anisotropy is reduced, and μ' in the high-frequency region is further improved. From the viewpoint of further reducing magnetic anisotropy and further improving μ' in the high-frequency region, the Mn amount (e) is more preferably 0.064 or more, and more preferably 0.22 or less. In addition, the Zr amount (d) is more preferably 0.20 or more, and more preferably 0.40 or less.

[0094] In the sintered body of this embodiment, although there are no particular limitations, the ratio of (Ni+Cu) / Zn, expressed as a molar concentration ratio, corresponds to the Curie temperature, and the Curie temperature increases by increasing this ratio. A desirable range for (Ni+Cu) / Zn is 0.5 to 1.1.

[0095] The characteristic of this embodiment lies in the composition of the sintered body, and its manufacturing method is not limited. Conventional methods can be used as manufacturing methods. For example, multiple oxides can be used as raw materials, pure water can be added, and additives such as dispersants and stabilizers can be added. Instead of the oxides or together with the oxides, compounds such as halides and organometallic compounds that form oxides through sintering can be used.

[0096] The above-mentioned raw materials are mixed to obtain a raw material mixture. For example, as shown in the examples described later, a ball mill can be used for mixing and pulverizing. Next, the raw material mixture can be pre-calcined at, for example, 650°C to 850°C. After pre-calcination, it is pulverized to obtain a pulverized material. At this time, binders, sintering aids, etc., for molding and sintering can be added and mixed and pulverized. The pulverized mixture is granulated to obtain granules, and then the granules are molded to obtain a molded body. Then, the molded body can be formally fired in the range of, for example, 900°C to 1200°C to obtain a sintered body.

[0097] Example

[0098] The present invention will be further illustrated below with examples. The present invention is not limited to the following examples, and appropriate modifications may be made to implement it within the scope of the above and following spirit, all of which are included within the technical scope of the present invention.

[0099] [Preparation of ferrite sintered bodies]

[0100] [Example 1]

[0101] First, Fe2O3, CuO, NiO, ZnO, Mn2O3, ZrO2, Al2O3, Co3O4, and Cr2O3 were weighed as raw materials to achieve the composition of the calcined product as shown in Examples 1-1 to 1-9 of Table 1. In this example, high-purity oxide materials were prepared to strictly control the content of trace amounts of Al, Co, and Cr. The purity of the oxide materials was: Fe2O3: 99.9%, ZnO: 99.7%, NiO: 99.3%, and CuO: 99.96%. It should be noted that since the amount of other oxide materials used was trace, the influence of any impurities was considered minimal.

[0102] The weighed raw materials, along with pure water, dispersant, and PSZ (partially stabilized zirconia) balls, were placed in a ball mill and wet-mixed and pulverized for 6 hours. After evaporation and drying, the mixture was pre-calcined at 750°C for 2 hours to produce the pre-calcined material (pre-calcined powder).

[0103] The obtained pre-calcined powder was placed in a ball mill with pure water, binder (acrylic binder), defoamer, and PSZ balls for wet mixing and pulverization. The resulting slurry was evaporated and dried, then granulated to obtain granular powder. The granular powder was filled into a mold with an inner diameter of 12 mm and an outer diameter of 20 mm, and pressurized to obtain a ring-shaped body. The body was then fired in a furnace at the firing temperatures listed in Table 1 under atmospheric conditions for 1 hour to obtain a ring-shaped ferrite sintered body.

[0104] [Example 2]

[0105] Fe2O3, CuO, NiO, ZnO, Mn2O3, ZrO2, Al2O3, Co3O4, and Cr2O3 were weighed as raw materials to make the composition after firing the same as that in Examples 2-1 to 2-7 of Table 1. Otherwise, the sintered body was made in the same manner as in Example 1.

[0106] [Example 3]

[0107] Fe2O3, CuO, NiO, ZnO, Mn2O3, ZrO2, Al2O3, Co3O4, and Cr2O3 were weighed as raw materials to make the composition after firing the same as that in Examples 3-1 to 3-5 in Table 1. Otherwise, the sintered body was made in the same way as in Example 1.

[0108] [Comparative Example]

[0109] Fe2O3, CuO, NiO, ZnO, Mn2O3, ZrO2, Al2O3, Co3O4, and Cr2O3 were weighed as raw materials to make the composition after firing the same as that of Comparative Examples 1-1 to 1-12 in Table 1. Otherwise, the sintered body was prepared in the same manner as in Example 1.

[0110] [Evaluation of ferrite sintered bodies]

[0111] Using the ferrite sintered bodies obtained in [Example 1], [Example 2], [Example 3] and [Comparative Example] above, the μ' and Curie temperature at 100 kHz were determined as follows. Furthermore, the ferrite sintered bodies were observed under a microscope to confirm the presence or absence of Cu segregation and to analyze their composition.

[0112] (Determination of μ' and Curie temperature at 100 kHz)

[0113] The μ' at 100 kHz was measured using an impedance analyzer (model 4294A, manufactured by KEYSIGHT TECHNOLOGIES). The obtained μ' at 100 kHz is shown in Table 1.

[0114] In addition, Cu wire was wound 20 times onto the sintered body, and the temperature characteristics of μ' at 100 kHz were measured using an LCR meter (model E4980, Agilent) to calculate the Curie temperature. The Curie temperature was calculated as follows: In a coordinate graph with temperature on the horizontal axis and μ' at 100 kHz on the vertical axis, with room temperature μ' set to 100%, the temperature at which the straight line passing through the points where μ' is 80% and 20% is μ' = 1 was taken as the Curie temperature. During temperature measurement, the sintered body was placed in a constant temperature bath (model STH-120, ESPEC) and the temperature was varied from room temperature to 200°C. The calculated Curie temperatures (Tc) are shown in Table 1.

[0115] (Microscopic observation)

[0116] The sintered bodies described above were cut and embedded in resin using epoxy resin and a curing agent to allow observation of the cross-sections of the annular ferrite sintered bodies of Examples 1-1 and Comparative Examples 1-3, which were substantially perpendicular to the circumferential direction and substantially horizontal to the axial and radial directions. The cut surfaces of the resin-embedded sintered bodies were mirror-polished using an automatic grinding machine. The mirror-polished surfaces were then subjected to SEM-WDX analysis using a scanning electron microscope (JEOL Ltd., JXA-8530F) to obtain reflected electron images and determine the Cu distribution. The results are shown below. Figure 1 .exist Figure 1 As can be seen, more Cu segregation, appearing as white spots, was observed in the comparative example than in the examples. As stated above, it is presumed that the Cu segregation in this comparative example was due to the Al, Co, and Cr contents being outside the specified range.

[0117] (Component composition analysis and calculation of α and β values)

[0118] The sintered body was pulverized in a mortar, and the contents of Fe, Zn, Ni, Cu, Zr, Mn, Al, Co, and Cr were determined by ICP-AES / MS. The molar contents of these elements relative to 100 moles of Fe are shown in Table 1. Furthermore, when the molar contents of Zn, Ni, Cu, Zr, and Mn relative to 100 moles of Fe were set as a, b, c, d, and e, respectively, the α value (=100-a-b-c+2d+(1 / 2)e) and β value (=a+b+c+d+e / 2) were calculated. Additionally, the (Ni+Cu) / Zn ratio, which is closely related to the Curie temperature, was also calculated. These results are shown in Table 1.

[0119]

[0120]

[0121] Examples 1-1 to 1-9 of [Example 1], Examples 2-1 to 2-7 of [Example 2], and Comparative Examples 1-1 to 1-12 are examples of controlling the (Ni+Cu) / Zn ratio to achieve a Curie temperature of approximately 140°C. Based on these examples, the effect of composition on μ' at 100 kHz within this Curie temperature range was confirmed.

[0122] A comparison of Example 1-1 with Comparative Examples 1-1 and 1-2 shows that when the upper and lower limits of the Al content (f) are exceeded, the μ' in the high-frequency region decreases. Furthermore, a comparison of Example 1-1 with Comparative Examples 1-3 to 1-5 shows that when the Co content (g) and Cr content (h) exceed their upper and lower limits, the μ' in the high-frequency region also decreases. These comparisons demonstrate that by strictly controlling the contents of Al, Co, and Cr within an appropriate range of trace amounts, the μ' in the high-frequency region can be reliably improved.

[0123] Examples 1-2 to 1-4 are examples of changing the value of α. A comparison of Examples 1-2 to 1-4 with Comparative Examples 1-6 shows that when the value of α exceeds the upper limit and the value of β exceeds the lower limit, μ' in the high-frequency region decreases.

[0124] Examples 1-5 and Examples 2-1 to 2-4 are examples of changing the Zr amount (d). Comparative Examples 1-7 to 1-10 are also examples of changing the Zr amount (d), and the α value exceeds the range of the present invention. From the comparison of Examples 1-5 and Examples 2-1 to 2-4 with Comparative Examples 1-7 to 1-10, it can be seen that as the Zr amount (d) increases, μ' in the high-frequency region increases, but even with excessive increase in Zr amount, the increase in μ' in the high-frequency region saturates. Furthermore, even with an increase in Zr amount (d), if the α value exceeds the lower limit, μ' in the high-frequency region decreases. In particular, from the comparison of Comparative Examples 1-7 to 1-9 with Comparative Examples 1-10, it can be seen that when both the upper limits of Zr amount (d) and β value are exceeded, μ' in the high-frequency region decreases significantly.

[0125] Comparing Examples 2-1 and Examples 1-9, it can be seen that by keeping the amount of Mn within a preferred range, μ' is further increased in the high-frequency region.

[0126] Examples 1-6 to 1-8 are examples with a relatively high Mn content (e). When Mn exceeds the preferred range, the effect of increasing μ' in the high-frequency region brought about by Zr addition is weakened. Comparing Examples 1-5 and Examples 2-1 to 2-4 with Examples 1-6 to 1-8, it can be seen that when the Zr content is below 0.34, the μ' in the high-frequency region is high in the examples with a high Mn content, but when the Zr content is 0.34, the μ' in the high-frequency region is high in the examples with a low Mn content.

[0127] Examples 2-5 to 2-7 illustrate variations in the α value and the Zr quantity (d). Comparing these examples with Comparative Example 1-11, it is evident that when the α value and Zr increase, μ' in the high-frequency region increases; however, when the α value exceeds the upper limit, μ' in the high-frequency region decreases. Comparing Comparative Example 1-11 and Comparative Example 1-12, where the α value exceeds the range, it is evident that the Zr quantity (d) exceeds the upper limit along with the α value, thereby further reducing μ' in the high-frequency region.

[0128] Based on the above examples, by setting the α and β values, i.e., the amounts of [Fe2O3+Mn2O3+(3 / 2)ZrO2] and Fe2O3, within a specified range, it is possible to suppress the decrease in μ' in the high-frequency region due to relaxation loss. Furthermore, by setting the Al, Co, and Cr amounts within a specified range, Cu segregation can be suppressed. As a result, a high μ' of over 1600 is achieved in the high-frequency region near Tc = 140℃.

[0129] Furthermore, as shown in [Example 2], by further reducing the Zr and Mn amounts to a specified range, the magnetic anisotropy is reduced, and a higher μ' of over 1700 is achieved in the high-frequency region near Tc = 140°C.

[0130] Furthermore, Examples 3-1 to 3-5 of [Example 3] are examples of changing Tc by altering (Ni+Cu) / Zn. Although Tc and μ' are in a trade-off relationship, in these examples, a high μ' in the high-frequency region is obtained in each Tc.

[0131] This application claims priority to Japanese Patent Application No. 2021-176701, which is incorporated herein by reference.

[0132] Industrial availability

[0133] The sintered body of the present invention can be used as a sintered magnetic component in various electromagnetic devices, such as inductors, transformers, coils, etc.

Claims

1. A sintered body comprising a spinel-type ferrite oxide, wherein the main metallic elements of the spinel-type ferrite oxide are Fe, Ni, Cu, and Zn. It also contains Zr, Mn, Al, Co, and Cr. in, When Fe is set to 100 molar parts, and the molar contents of Zn, Ni, Cu, Zr, Mn, Al, Co, and Cr are set to a, b, c, d, e, f, g, and h respectively, 100-a-b-c+2d+(1 / 2)e, a+b+c+d+e / 2, f, g, and h respectively satisfy the following equations (1) to (5), where a is in the range of 23.9~34.6, b is in the range of 6.7~27.0, and c is in the range of 0.1~10.

2. 49.0<100-a-b-c+2d+(1 / 2)e<50.0···(1) 50.2<a+b+c+d+e / 2<52.7···(2) 0.0012≤f≤0.010···(3) 0.0005≤g≤0.0015···(4) 0.0005≤h≤0.004···(5)。 2. The sintered body according to claim 1, wherein, The d satisfies the following equation (6) and the e satisfies the following equation (7). 0.10≤d≤0.50···(6) 0.055≤e≤0.25···(7)。

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