Ferrite sintered body

Abstract

The present invention provides a ferrite sintered body comprising Co and Fe, wherein the Co content is 38-60 mol% in terms of CoO, the Fe content is 40-50 mol% in terms of Fe2O3, and the average particle size of the sintered body is 1.0-5.0 μm.

Description

Technical Field

[0001] The present disclosure relates to a ferrite sintered body.

Background Art

[0002] In recent years, communication devices have been operating at higher frequencies, and inductance elements suitable for use at higher frequencies have been demanded. Conventionally, MnZn-based ferrites and NiZn-based ferrites have been used for inductance elements for high frequencies, but the real part of their magnetic permeability begins to attenuate in the MHz band. In response to such a problem, Patent Document 1 discloses a Co-based ferrite as a ferrite in which the real part of the magnetic permeability is less likely to attenuate at MHz.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The Co ferrite disclosed in Patent Document 1 has a real part of the magnetic permeability that is less likely to attenuate in the high frequency band, but the imaginary part of the magnetic permeability rises from a lower frequency band than 1 GHz, for example, around 0.2 GHz. Therefore, the Co ferrite disclosed in Patent Document 1 has a problem of large magnetic loss in the high frequency band.

[0005] An object of the present invention is to provide a ferrite sintered body in which attenuation of the real part of the magnetic permeability and rise of the imaginary part of the magnetic permeability are suppressed even in the high frequency band.

Means for Solving the Problems

[0006] The present disclosure includes the following aspects. [1] A ferrite sintered body containing Co and Fe, The content of Co is 38 mol% or more and 60 mol% or less in terms of CoO, the content of Fe is 40 mol% or more and 50 mol% or less in terms of Fe2O3, the average particle diameter of the sintered body is 1.0 μm or more and 5.0 μm or less, ferrite sintered body. [2] The ferrite sintered body according to [1] above, wherein the content of Co is 41 mol% or more and 60 mol% or less in terms of CoO. [3] The ferrite sintered body according to [1] or [2] above, further containing more than 0 mol% and 9 mol% or less of Zn in terms of ZnO. [4] The ferrite sintered body according to any one of [1] to [3] above, further containing more than 0 mol% and 9 mol% or less of Ni in terms of NiO. [5] The ferrite sintered body according to any one of [1] to [3] above, further containing a total of more than 0 mol% and 9 mol% or less of Cu and Ni in terms of CuO and NiO, respectively. [6] The ferrite sintered body according to any one of [1] to [5] above, wherein the average particle diameter of the sintered body is 1.4 μm or more and 4.0 μm or less. [7] Ferrite powder containing Co and Fe, wherein the content of Co is 38 mol% or more and 60 mol% or less in terms of CoO, the content of Fe is 40 mol% or more and 50 mol% or less in terms of Fe2O3, the BET specific surface area is 5.0 m 2 / g or more and 10 m 2 / g or less, ferrite powder. [8] The ferrite powder according to [7] above, wherein the content of Co is 41 mol% or more and 60 mol% or less in terms of CoO. [9] The ferrite powder according to [7] or [8] above, further containing more than 0 mol% and 9 mol% or less of Zn in terms of ZnO.

[10] Further, the ferrite powder according to any one of [7] to [9] above, containing Ni in terms of NiO in an amount of more than 0 mol% and 9 mol% or less.

[11] Further, the ferrite powder according to any one of [7] to [9] above, containing Cu and Ni in terms of CuO and NiO, respectively, in a total amount of more than 0 mol% and 9 mol% or less.

[12] The BET specific surface area is 7.0 m 2 / g or more and 9.0 m 2 / g or less, the ferrite powder according to any one of [7] to

[11] above.

[13] A method for manufacturing a ferrite sintered body, CoO is 38 mol% or more and 60 mol% or less, Fe2O3 is 40 mol% or more and 50 mol% or less, ZnO is 0 mol% or more and 9 mol% or less, CuO is 0 mol% or more and 9 mol% or less, NiO is 0 mol% or more and 9 mol% or less, However, the total of CuO and NiO is 0 mol% or more and 9 mol% or less, obtaining a mixture of oxides containing the above, calcining the mixture of the oxides at a temperature of 600°C or more and 700°C or less to obtain a calcined product, grinding the calcined product so that the BET specific surface area is 5.0 m 2 / g or more and 10 m 2 / g or less to obtain a ground product, forming the ground product to obtain a formed body, and firing the formed body at a temperature of 1000°C or more and 1150°C or less to obtain a sintered body A method for manufacturing a ferrite sintered body, including the above. [Effect of the Invention]

[0007] According to the present disclosure, it is possible to provide a ferrite sintered body in which attenuation of the real part of the magnetic permeability and rise of the imaginary part of the magnetic permeability are suppressed even in the high-frequency conduction band. [Embodiment for Carrying Out the Invention]

[0008] Hereinafter, the ferrite sintered body of the present disclosure will be described.

[0009] The ferrite sintered body of the present disclosure contains at least Co and Fe.

[0010] The content of Co in the ferrite sintered body, in terms of CoO, is 38 mol% or more, preferably 41 mol% or more, for example 45 mol% or more, and 60 mol% or less, for example 55 mol% or less, or 50 mol% or less, based on the total of the metal elements (in terms of oxide) contained in the ferrite sintered body. In a preferred embodiment, the content of Co, in terms of CoO, can be 38 mol% or more and 60 mol% or less, preferably 41 mol% or more and 60 mol% or less, based on the total of the metal elements (in terms of oxide) contained in the ferrite sintered body.

[0011] The content of Fe in the ferrite sintered body, in terms of Fe2O3, is 40 mol% or more, for example 45 mol% or more, and 50 mol% or less, for example 47 mol% or less, based on the total of the metal elements (in terms of oxide) contained in the ferrite sintered body. In a preferred embodiment, the content of Fe, in terms of Fe2O3, can be 40 mol% or more and 50 mol% or less, for example 40 mol% or more and 47 mol% or less, based on the total of the metal elements (in terms of oxide) contained in the ferrite sintered body.

[0012] By setting the contents of Co and Fe in the ferrite sintered body within the above ranges, it is possible to suppress the attenuation of the real part of the magnetic permeability and the rise of the imaginary part of the magnetic permeability in the high frequency band.

[0013] The ferrite sintered body of the present disclosure may further contain at least one selected from Zn, Ni, and Cu.

[0014] In one embodiment, the ferrite sintered body of the present disclosure further contains Zn.

[0015] The content of Zn in the above ferrite sintered body, in terms of ZnO conversion, is more than 0 mol%, preferably 1 mol% or more, for example 5 mol% or more, and 9 mol% or less, for example 8 mol% or less, based on the total of the metal elements (in terms of oxide conversion) contained in the ferrite sintered body. In a preferred embodiment, the content of Zn, in terms of ZnO conversion, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, based on the total of the metal elements (in terms of oxide conversion) contained in the ferrite sintered body.

[0016] By setting the content of Zn in the above ferrite sintered body within the above range, the real part of the magnetic permeability in the high-frequency band can be increased.

[0017] In one embodiment, the ferrite sintered body of the present disclosure further contains Ni.

[0018] The content of Ni in the above ferrite sintered body, in terms of NiO conversion, is more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxide conversion) contained in the ferrite sintered body. In a preferred embodiment, the content of Ni, in terms of NiO conversion, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, based on the total of the metal elements (in terms of oxide conversion) contained in the ferrite sintered body.

[0019] By setting the content of Ni in the above ferrite sintered body within the above range, the coercive force can be increased, and the rise of the imaginary part of the magnetic permeability in the high-frequency band can be suppressed.

[0020] In one embodiment, the ferrite sintered body of the present disclosure further contains Cu.

[0021] The content of Cu in the above ferrite sintered body, in terms of CuO, is more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite sintered body. In a preferred embodiment, the content of Cu, in terms of CuO, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite sintered body.

[0022] By setting the content of Cu in the above ferrite sintered body within the above range, the rise of the imaginary part of the magnetic permeability in the high-frequency band can be suppressed.

[0023] In one embodiment, the ferrite sintered body of the present disclosure further contains Cu and Ni.

[0024] In this embodiment, the contents of Cu and Ni in the ferrite sintered body, in terms of CuO and NiO respectively, in total are more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite sintered body. In a preferred embodiment, the total content of Cu and Ni can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, in terms of CuO and NiO respectively, based on the total of the metal elements (in terms of oxides) contained in the ferrite sintered body.

[0025] By setting the contents of Cu and Ni in the above ferrite sintered body within the above range, the rise of the imaginary part of the magnetic permeability in the high-frequency band can be suppressed.

[0026] In a preferred embodiment, the ferrite sintered body of the present disclosure substantially does not contain metal elements other than the above Fe, Co, Zn, Ni, and Cu. Here, "substantially does not contain" means not containing metal elements in an amount exceeding the impurity level, and for example, it may contain an unavoidably small amount of metal elements during production. For example, "substantially does not contain metal elements" means that the content of metal elements is 0.01 mol% or less in terms of oxide conversion.

[0027] In one embodiment, the metal elements contained in the ferrite sintered body of the present disclosure are substantially only Co and Fe.

[0028] In another embodiment, the metal elements contained in the ferrite sintered body of the present disclosure are substantially only Co, Fe, and Zn.

[0029] In another embodiment, the metal elements contained in the ferrite sintered body of the present disclosure are substantially only Co, Fe, and Ni.

[0030] In another embodiment, the metal elements contained in the ferrite sintered body of the present disclosure are substantially only Co, Fe, Zn, and Ni.

[0031] In another embodiment, the metal elements contained in the ferrite sintered body of the present disclosure are substantially only Co, Fe, Zn, Ni, and Cu.

[0032] In another embodiment, the above ferrite sintered body may further contain additive components. Examples of the above additive components include, but are not limited to, Bi, Sn, etc. The Bi content (addition amount) can be 0.1 to 1 part by mass in terms of Bi2O3 with respect to 100 parts by mass in total of the above Co (in terms of CoO conversion), Fe (in terms of Fe2O3 conversion), Zn (in terms of ZnO conversion), Cu (in terms of CuO conversion), and Ni (in terms of NiO conversion). Also, the Sn content (addition amount) can be 0.3 to 1.0 parts by mass in terms of SnO2 with respect to 100 parts by mass in total of the above Co (in terms of CoO conversion), Fe (in terms of Fe2O3 conversion), Zn (in terms of ZnO conversion), Cu (in terms of CuO conversion), and Ni (in terms of NiO conversion).

[0033] The average particle size of the sintered body is 1.0 μm or more, preferably 1.4 μm or more, for example 1.9 μm or more, and 5.0 μm or less, preferably 4.0 μm or less, for example 3.2 μm or less. In a preferred embodiment, the average particle size of the sintered body can be 1.0 μm or more and 5.0 μm or less, preferably 1.4 μm or more and 4.0 μm or less.

[0034] By setting the average particle size of the ferrite sintered body within the above range, the coercive force can be improved, the real part of the magnetic permeability in the high-frequency band can be increased, and the rise of the imaginary part can be suppressed.

[0035] The average particle size of the ferrite sintered body is calculated as the particle size at which the integrated value of the area becomes 50% by obtaining the equivalent circle diameters of 30 or more (for example, 30 or more and 50 or less) particles from an image obtained by observing the polished surface of the polished sintered body with SEM.

[0036] The magnetic permeability of the ferrite sintered body is preferably such that the real part μ' is 1.3 or more and 2.7 or less, and the imaginary part μ'' is 0.01 or more and 0.8 or less at a frequency of 1 GHz or more and 5 GHz or less.

[0037] The ferrite sintered body of the present disclosure can be obtained by firing the ferrite powder of the present disclosure.

[0038] The ferrite powder of the present disclosure contains Co and Fe.

[0039] The content of Co in the ferrite powder, in terms of CoO, is 38 mol% or more, preferably 41 mol% or more, for example 45 mol% or more, and 60 mol% or less, for example 55 mol% or less, or 50 mol% or less, based on the total of the metal elements contained in the ferrite powder (in terms of oxide). In a preferred embodiment, the content of Co can be 38 mol% or more and 60 mol% or less, preferably 41 mol% or more and 60 mol% or less, in terms of CoO, based on the total of the metal elements contained in the ferrite powder (in terms of oxide).

[0040] The content of Fe in the ferrite powder is 40 mol% or more, for example 45 mol% or more, and 50 mol% or less, for example 47 mol% or less, in terms of Fe2O3 with respect to the total of metal elements (in terms of oxide) contained in the ferrite powder. In a preferred embodiment, the content of Fe may be 40 mol% or more and 50 mol% or less, for example 40 mol% or more and 47 mol% or less, in terms of Fe2O3 with respect to the total of metal elements (in terms of oxide) contained in the ferrite powder.

[0041] By setting the contents of Co and Fe in the ferrite powder within the above ranges, it is possible to suppress the attenuation of the real part of the magnetic permeability and the rise of the imaginary part of the magnetic permeability in the high-frequency band when fired.

[0042] The ferrite powder of the present disclosure may further contain at least one selected from Zn, Ni, and Cu.

[0043] In one embodiment, the ferrite powder of the present disclosure further contains Zn.

[0044] The content of Zn in the ferrite powder is more than 0 mol%, preferably 1 mol% or more, for example 5 mol% or more, and 9 mol% or less, for example 8 mol% or less, in terms of ZnO with respect to the total of metal elements (in terms of oxide) contained in the ferrite powder. In a preferred embodiment, the content of Zn may be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, in terms of ZnO with respect to the total of metal elements (in terms of oxide) contained in the ferrite powder.

[0045] By setting the content of Zn in the ferrite powder within the above range, it is possible to increase the real part of the magnetic permeability in the high-frequency band when fired.

[0046] In one embodiment, the ferrite powder of the present disclosure further contains Ni.

[0047] The content of Ni in the ferrite powder, in terms of NiO, is more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder. In a preferred embodiment, the content of Ni, in terms of NiO, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder.

[0048] By setting the content of Ni in the ferrite powder within the above range, the BET specific surface area increases, and the average particle size of the resulting sintered body decreases. As a result, the coercive force of the sintered body increases, and the rise of the imaginary part of the magnetic permeability in the high-frequency band can be suppressed.

[0049] In one embodiment, the ferrite powder of the present disclosure further contains Cu.

[0050] The content of Cu in the ferrite powder, in terms of CuO, is more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder. In a preferred embodiment, the content of Cu, in terms of CuO, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder.

[0051] By setting the content of Cu in the ferrite powder within the above range, the rise of the imaginary part of the magnetic permeability in the high-frequency band during firing can be suppressed.

[0052] In one embodiment, the ferrite powder of the present disclosure further contains Cu and Ni.

[0053] In this embodiment, the contents of Cu and Ni in the ferrite powder, when converted to CuO and NiO respectively, are in total more than 0 mol%, preferably 1 mol% or more, for example 3 mol% or more, and 9 mol% or less, for example 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder. In a preferred embodiment, the total content of Cu and Ni, when converted to CuO and NiO respectively, can be more than 0 mol% and 9 mol% or less, preferably 1 mol% or more and 9 mol% or less, for example 3 mol% or more and 6 mol% or less, based on the total of the metal elements (in terms of oxides) contained in the ferrite powder.

[0054] By setting the contents of Cu and Ni in the ferrite powder within the above ranges, it is possible to suppress the rise of the imaginary part of the magnetic permeability in the high-frequency band during firing.

[0055] In a preferred embodiment, the ferrite powder of the present disclosure substantially does not contain metal elements other than the above Fe, Co, Zn, Ni, and Cu. Here, substantially not containing means not containing metal elements in an amount exceeding the impurity level, and for example, it may contain an amount of metal elements unavoidable in production. For example, substantially not containing metal elements means that the content of metal elements is 0.01 mol% or less in terms of oxides.

[0056] In one embodiment, the metal elements contained in the ferrite powder of the present disclosure are substantially only Co and Fe.

[0057] In another embodiment, the metal elements contained in the ferrite powder of the present disclosure are substantially only Co, Fe, and Zn.

[0058] In another embodiment, the metal elements contained in the ferrite powder of the present disclosure are substantially only Co, Fe, and Ni.

[0059] In another embodiment, the metal elements contained in the ferrite powder of the present disclosure are substantially only Co, Fe, Zn, and Ni.

[0060] In another aspect, the metal elements contained in the ferrite powder of the present disclosure are substantially only Co, Fe, Zn, Ni, and Cu.

[0061] In another aspect, the ferrite powder may further contain additive components. Examples of the additive components include, but are not limited to, Bi, Sn, etc. The Bi content (added amount) can be 0.1 to 1 part by mass in terms of Bi2O3 with respect to 100 parts by mass in total of the above Co (in terms of CoO), Fe (in terms of Fe2O3), Zn (in terms of ZnO), Cu (in terms of CuO), and Ni (in terms of NiO). Also, the Sn content (added amount) can be 0.3 to 1.0 part by mass in terms of SnO2 with respect to 100 parts by mass in total of the above Co (in terms of CoO), Fe (in terms of Fe2O3), Zn (in terms of ZnO), Cu (in terms of CuO), and Ni (in terms of NiO).

[0062] The BET specific surface area of the above powder is 5.0 m 2 / g or more, preferably 7.0 m 2 / g or more, for example 8.0 m 2 / g or more, and 10 m 2 / g or less, preferably 9.0 m 2 / g or less, for example 8.6 m 2 / g or less. In a preferred embodiment, the average particle size of the above powder is 5.0 m 2 / g or more and 10 m 2 / g or less, preferably 7.0 m 2 / g or more and 9.0 m 2 / g or less.

[0063] By setting the BET specific surface area of the above ferrite powder within the above range, the firing temperature can be lowered, and the average particle size of the sintered body after firing can be reduced.

[0064] The BET specific surface area of the above ferrite powder is obtained by preparing a slurry of the ferrite powder and measuring the BET specific surface area of the ferrite powder in the slurry with a specific surface area measuring device (for example, Macsorb (registered trademark) manufactured by Mountech Co., Ltd.).

[0065] The above ferrite powder can be obtained by mixing oxides of respective metal elements as raw materials and calcining the obtained mixture at a predetermined temperature.

[0066] Specifically, CoO is 38 mol% or more and 60 mol% or less, Fe2O3 is 40 mol% or more and 50 mol% or less, ZnO is 0 mol% or more and 9 mol% or less, CuO is 0 mol% or more and 9 mol% or less, NiO is 0 mol% or more and 9 mol% or less, However, the total of CuO and NiO is 0 mol% or more and 9 mol% or less, are mixed to obtain a mixture of oxides, and then the obtained mixture of oxides is fired at a temperature of 600°C or more and 700°C or less, preferably 620°C or more and 680°C or less, and the obtained calcined product is pulverized to obtain a ferrite powder having a BET specific surface area of 5.0 m 2 / g or more and 10 m 2 / g or less.

[0067] The present disclosure also provides a method for manufacturing a ferrite sintered body.

[0068] The ferrite sintered body of the present disclosure contains CoO in an amount of 38 mol% or more and 60 mol% or less, Fe2O3 in an amount of 40 mol% or more and 50 mol% or less, ZnO in an amount of 0 mol% or more and 9 mol% or less, CuO in an amount of 0 mol% or more and 9 mol% or less, NiO in an amount of 0 mol% or more and 9 mol% or less, However, the total of CuO and NiO is 0 mol% or more and 9 mol% or less, to obtain a mixture of oxides containing the same, calcining the obtained mixture of oxides at a temperature of 600°C or more and 700°C or less to obtain a calcined product, subjecting the obtained calcined product to a BET specific surface area of 5.0 m 2 / g or more and 10 m2 Crush it so that it becomes / g or less to obtain a crushed product, Mold the obtained crushed product to obtain a molded body, and Firing the obtained molded body at a temperature of 1000 ° C or higher and 1150 ° C or lower to obtain a sintered body.

[0069] The sintered body of the present disclosure has a high coercive force, and the attenuation of the real part of the magnetic permeability and the rise of the imaginary part of the magnetic permeability in the high frequency band are suppressed. Therefore, it is preferably used in an inductor element or the like.

[0070] Therefore, the present disclosure provides an inductor element including a base body including a ferrite sintered body and a coil embedded in the base body, wherein the ferrite sintered body is the ferrite sintered body of the present disclosure.

[0071] Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

Example

[0072] CoO, Fe2O3, ZnO, CuO, and NiO were weighed at a predetermined ratio shown in Table 1 so that the total amount of the oxides was 300 g, and 300 g of pure water, 6 g of a dispersant of ammonium polycarboxylate, and 1.2 kg of 2 mmφ PSZ jade stones were placed in a 1000 cc polyester material pot and mixed for 16 hours with a ball mill at a rotation speed of 116 rpm. The obtained mixture was evaporated and dried at a temperature of 120 ° C to obtain a mixed dried powder. This mixed dried powder was passed through a sieve having a coarseness of 425 μm to obtain a sized powder. This sized powder was calcined in air at 650 ° C for 2 hours to obtain a calcined powder. The crystal structure of the obtained calcined powder was a spinel-type single phase.

[0073] To 90 g of the calcined powder obtained above, 63 g of pure water, 1.8 g of a dispersant of ammonium polycarboxylate, and 600 g of 5 mmφ PSZ jade stones were placed in a 500 cc polyester material pot and pulverized for 16 hours with a ball mill at a rotation speed of 154 rpm to obtain a slurry atomized into fine particles. Table 1 shows the results of measuring the average particle diameter of the Co-based ferrite powder contained in the obtained slurry with a laser diffraction / scattering particle size distribution measuring device (manufactured by Horiba, Ltd.). Table 1 also shows the results of measuring the BET specific surface area of the Co-based ferrite powder contained in this slurry with a specific surface area measuring device Macsorb (registered trademark) (manufactured by Mountech Co., Ltd.).

[0074] To the atomized slurry obtained above, 10 g of an acrylic binder having a molecular weight of 20,000 and 0.5 g of dibutyl phthalate as a plasticizer were added, and sheet forming was carried out by the doctor blade method (sheet material polyethylene terephthalate, gap between blade and sheet 200 μm, drying temperature 60 °C, sheet winding speed 20 cm / min). The obtained sheet was punched out into a 4.5×2.5 cm square, and the polyethylene terephthalate sheet was peeled off to obtain a ferrite sheet. The ferrite sheets were stacked so that the total sheet thickness was 1.5 mm. The obtained laminate was placed in a stainless steel mold, heated to 60 °C, and pressure-bonded from above and below with a pressure of 200 MPa to obtain a pressure-bonded body. The pressure-bonded body was cut into a 2×1.5×5 mm block for SEM observation to obtain a processed body. For magnetic permeability measurement, it was cut into a 18×5×0.3 mm square plate after sintering to obtain a processed body. The processed bodies of each shape were placed on a zirconia setter and heated in the air at a heating rate of 0.5 °C / min, a maximum temperature of 450 °C, and a maximum temperature holding time of 2 hours to thermally decompose and degrease the acrylic binder, etc., and then fired at a heating and cooling rate of 5 °C / min and a maximum temperature holding time of 2 hours to obtain sintered bodies of each shape.

[0075] The obtained sintered body in block shape was embedded in resin using an epoxy resin and a curing agent. The sintered body embedded in the resin was mirror-polished with an automatic polishing machine. The polished surface of the mirror-polished sintered body was observed by SEM, and after obtaining the equivalent circle diameters of 30 or more particles from the obtained image, the particle size at which the integrated value of the area became 50% was calculated as the average particle size. Also, the frequency characteristics of the magnetic permeability were measured with an E5071C ENA vector network analyzer (Keysight Technologies, Inc.) using a sintered body in rectangular plate shape, and the coercive force was measured using a VSM-5 type vibrating sample magnetometer manufactured by Toyo Corporation. The results are shown in Table 2.

[0076]

Table 1

[0077]

Table 2

[0078] From the above results, it was confirmed that the ferrite sintered body of the present disclosure has a high coercive force Hc of 4000 A / m or more, and also that the attenuation of the real part μ' of the magnetic permeability is suppressed even at 1 GHz and the rise of the imaginary part μ" does not occur. On the other hand, it was confirmed that the ferrite sintered body of the comparative example outside the scope of the present invention has a low retention rate, and further at 1 GHz, the real part of the magnetic permeability decreases or the rise of the imaginary part occurs.

Industrial Applicability

[0079] The ferrite material of the present disclosure can be used as a material for high-frequency electronic components, particularly inductance elements and the like.

Claims

1. A ferrite powder containing Co and Fe, wherein the content of Co is 38 mol% or more and 60 mol% or less in terms of CoO, The content of the Fe is 40 mol% or more and 50 mol% or less in terms of Fe ２ O ３ converted thereto, and The BET specific surface area is 7.0 m ２ / g or more and 9.0 m ２ / g or less, the ferrite powder.

2. The ferrite powder according to Claim 1, wherein the content of Co is 41 mol% or more and 60 mol% or less in terms of CoO.

3. The ferrite powder according to Claim 1 or 2, further containing more than 0 mol% and 9 mol% or less of Zn in terms of ZnO.

4. The ferrite powder according to Claim 1 or 2, further containing more than 0 mol% and 9 mol% or less of Ni in terms of NiO.

5. The ferrite powder according to Claim 1 or 2, further containing more than 0 mol% and 9 mol% or less in total of Cu and Ni in terms of CuO and NiO, respectively.

6. A method for manufacturing a ferrite sintered body, comprising: obtaining a mixture of oxides containing CoO at 38 mol% or more and 60 mol% or less, Fe ２ O ３ is 40 mol% or more and 50 mol% or less, ZnO at more than 0 mol% and 9 mol% or less, CuO at more than 0 mol% and 9 mol% or less, NiO at more than 0 mol% and 9 mol% or less, provided that the total of CuO and NiO is more than 0 mol% and 9 mol% or less; calcining the mixture of oxides at a temperature of 600°C or more and 700°C or less to obtain a calcined product; forming the pulverized product to obtain a formed body; and Crush the calcined product so that the BET specific surface area is 5.0 m ２ / g or more and 10 m ２ / g or less to obtain a crushed product. firing the formed body at a temperature of 1000°C or more and 1150°C or less to obtain a sintered body. A method for manufacturing a ferrite sintered body. ​

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