KR20080037521A - Hexagonal z type ferrite sintered material and method of fabricating the same - Google Patents

Abstract

A hexagonal Z type ferrite sintered material and a method for fabricating the same are provided to obtain high density by using a Ba-rich composition, high permeability, and low anisotropy of permeability. A hexagonal Z type ferrite sintered material includes a C-axis-oriented surface with a degree of orientation fc_ given as fc_= SigmaI(HK0)/I(HKL) of more than 0.4 when l(HKL) is integral intensity of a diffraction peak represented by an index(HKL), SigmaI(HKL) is total integral intensity of all diffraction peaks of a hexagonal Z type ferrite, and SigmaI(HK0) is total integral intensity of all diffraction peaks with L of 0 in an X-ray diffraction of which a measurement range is 2Theta=20 to 80 degrees. The degree of orientation fc// calculated from fc//=l(0018)/l(110) in an X-ray diffraction is not less than 0.3 in at least two surfaces which are perpendicular to the c-axis-oriented surface and are perpendicular to each other.

Description

Hexagonal jet ferrite sintered body and its manufacturing method {HEXAGONAL Z TYPE FERRITE SINTERED MATERIAL AND METHOD OF FABRICATING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to magnetic materials for high frequencies, and more particularly, to hexagonal Z type ferrites used for electronic components such as choke coils and noise canceling elements and radio wave absorbers in the high frequency band from several MHz to several GHz.

In recent years, with the high frequency of signals such as mobile phones, wireless LANs, and PCs, it is required that elements used in the apparatus also be used at high frequencies. In response to such a demand, in the spinel-based ferrites that have been conventionally used, since there is a frequency limit called a snake limit in the high frequency band, it is difficult to use it. For this reason, hexagonal ferrite having a hexagonal crystal structure has been studied as a high frequency material exceeding such a frequency limit.

Among hexagonal ferrites, in particular, Z-type ferrites containing cobalt (Co) are known to have relatively high permeability and to exhibit excellent high frequency characteristics. In addition, since Z-type ferrite containing cobalt (Co) has an easy magnetization surface, an operation of preparing the C-axis direction of crystal grains by a rotating magnetic field applied externally during molding (hereinafter, this operation is referred to as surface orientation). And the surface on which this operation is performed is called an orientation surface.) By performing the surface orientation, it is possible to improve the permeability in the alignment surface.

Japanese Patent Laid-Open No. 35-11280 (Patent Document 1) discloses that a Z-type ferrite can be oriented by applying a rotating magnetic field. In addition, Japanese Patent Application Laid-Open No. 48-97091 (Patent Document 2) applies a magnetic field from two orthogonal directions, and molds a hygroscopic mold so as to reduce the disturbance of the orientation, whereby a high level of surface orientation can be performed. There is description of the purpose. Further, WO 2004/097863 (Patent Document 3) discloses a Z-type ferrite face-oriented by rotating a mold in a certain magnetic field and molding.

Patent Documents 1 to 3 provide a technique for obtaining a sintered body in which Z-type ferrite crystals are surface-oriented.

However, in the invention described in patent documents 1 and 2, the apparatus and process which are involved in shaping | molding are complicated, and there exists a problem in productivity. In addition to the productivity, there is a possibility that the material is not necessarily preferable in view of the applicability of the material to the device. For example, in patent document 2, since surface orientation was performed, the high permeability exceeding 30 was obtained in the orientation surface, but the direction perpendicular | vertical to an orientation surface becomes a difficult direction of magnetization, and shows the value with permeability low as 3 or less. There is a description.

That is, the surface-oriented Z-type ferrite sintered compact described in patent documents 1-3 can be considered to be a sintered compact including the direction with such a low permeability. For example, the first table of Patent Document 2 discloses a ferrite having a magnetic permeability μ of 1.5 in the direction perpendicular to the easy magnetic screen. The magnetic permeability in this direction is not significantly different from the magnetic permeability 1 of the vacuum, and it can be considered that the magnetic permeability does not function substantially in that direction.

Therefore, such a plane-oriented Z-type ferrite can only be applied to the formation of two-dimensional pores, so that the application range has to be made extremely limited. That is, such extreme anisotropy is a big limitation when designing an inductance element.

In view of the above problems, an object of the present invention is to provide a hexagonal Z-type ferrite having a high permeability and excellent balance of permeability in addition to a high permeability in a specific direction, especially in a direction other than the direction, and a manufacturing method thereof. .

In view of the above problems, an object of the present invention is to provide a hexagonal Z-type ferrite having a high permeability and excellent balance of permeability in addition to a high permeability in a specific direction, especially in a direction other than the direction, and a manufacturing method thereof. .

The present invention is a hexagonal Z-type ferrite sintered body, in which the sum of the integral intensities of all diffraction peaks of hexagonal Z-type ferrite is ΣI (HKL) in an X-ray diffraction pattern having a measurement range of 2θ = 20 to 80 ° ( Where I (HKL) gives the integral intensity of the diffraction peaks shown by the exponent (HKL), and the sum of the integral intensity of the diffraction peaks of all (HK0) where L = 0 is ΣI (HK0), fc _⊥ = The orientation given by ΣI (HK0) / ΣI (HKL) also has a C-axis orientation plane where fc _⊥ is at least 0.4, and at least on two planes perpendicular to the C-axis orientation plane and perpendicular to each other, fC _{/ The} orientation calculated from _/ = I (0018) / I (110) is characterized in that fc _// is 0.3 or more.

According to the related structure, a hexagonal Z type ferrite sintered compact which has high permeability and small anisotropy of permeability can be provided.

The degree of orientation fc _⊥ is more preferably not less than 0.45. The orientation degree fc _// is more preferably 0.5 or more.

In addition, the present invention is a hexagonal Z-type ferrite sintered body, θ _AV = Σθn (θ) / Σn (θ) (where θ is a hexagonal Z-type ferrite sintered body in azimuth analysis by EBSP (Electron Back Scattering Pattern) Represents the azimuth angle difference between the direction perpendicular to the orientation analysis plane of the plane and the C-axis direction of the hexagonal Z-type ferrite at the measurement point of EBSP, and n (θ) represents the number of measurement points representing θ. Σn (θ) represents θn (θ) and n (θ) added to each other in a range from 0 to 90 °, respectively), and has a C-axis orientation plane with an average orientation difference θ _AV of 65 ° or more, n _AV = ΣI (φ) / m (where, φ represents an angle when the orientation difference between the projection direction to the azimuth analysis plane in the C-axis direction and one straight line in the azimuth analysis plane is a positive acute angle. I (φ) represents the number of measurement points representing the azimuth difference φ, and m represents the divided score between 0 and 90 °. By an average of the number of measurement points, and by SD = {ΣI (φ) -n AV) 2 / m} ^1/2 wherein the standard deviation divided by the SD SD / _AV n of 0.6 or less are given in.

According to the related structure, a hexagonal Z type ferrite sintered compact which has high permeability and small anisotropy of permeability can be provided.

In addition, the hexagonal Z-type ferrite sintered body includes BaO, CoO, Fe ₂ O ₃ as a main component, and its composition is preferably Ba-rich than the stoichiometric composition Ba ₃ Co ₂ Fe ₂₄ O ₄₁ of hexagonal Z-type ferrite. Do. Densification can be achieved by using a Ba-rich composition.

Further, in the hexagonal Z-type ferrite sintered body, the sintered compact density is preferably 5.0 × 10 ³ kg / m ³ or more. By making the sintered compact density into a relevant range, it contributes to the improvement of permeability. The sintered compact density of 5.0x10 <^3> kg / m <^3> or more is more preferable for obtaining permeability of 40 or more. From the related point of view, the sintered compact is more preferably at least 5.1 × 10 ³ kg / m ³ .

Further, in the hexagonal Z-type ferrite sintered body, when the magnetic permeability in the direction perpendicular to the C-axis alignment surface is μ _⊥ and the magnetic permeability in the direction parallel to the C-axis alignment surface is μ _// , For a magnetic permeability μ _// in at least two directions parallel and orthogonal to each other, it is preferable that the ratio μ _// / μ _⊥ is equal to or less than 0.6 at 100 kHz and / or 100 MHz.

The small ratio μ _// / μ _의미 means that the orientation is good, and that high μ _높은 can be obtained at the same time. The permeability ratio is more preferably 0.4 or less. Further, the ratio μ _// / μ _⊥ is more preferably not less than 0.1.

When the orientation is increased, the magnetic permeability in the direction parallel to the C-axis alignment surface is lowered. If the difference in permeability between the direction perpendicular to the C-axis alignment surface and the direction parallel to the C-axis alignment surface becomes too large, it becomes difficult to use the C-axis alignment surface direction as the magnetic path direction, thereby increasing the constraint on the magnetic circuit design. do.

In particular, in the conventional plane orientation in which the C axis is aligned in one direction of the C-axis alignment plane inward direction, the magnetic permeability ratio μ _// / μ _의 in this direction becomes extremely small, so it is practically difficult to use this direction in the magnetic path direction.

In the permeability at 100 kHz, the permeability is measured by inserting a hexagonal Z-type ferrite sintered body sample piece into the gap provided in the existing ring sample and measuring the permeability. The permeability at 100 MHz is described later. The value by the ring method is used. The detailed description of this measuring method is mentioned later.

Further, in the hexagonal Z-type ferrite sintered body, it is preferable that the magnetic permeability at 100 kHz in the direction perpendicular to the C-axis alignment plane is 30 or more. In order to form a high inductance element, the permeability is more preferably 35 or more, and still more preferably 40 or more. In order to form an inductance element exhibiting high inductance at a high frequency, the magnetic permeability at 100 MHz is preferably 30 or more, more preferably 35 or more.

In the hexagonal Z-type ferrite sintered body, it is preferable that the magnetic permeability at 100 kHz in at least two directions parallel to and perpendicular to the C-axis alignment plane is 8 or more.

In the present invention, the permeability in the direction perpendicular to the C-axis alignment surface is particularly high, but according to the above configuration, a high permeability can be exhibited even in a direction parallel to the C-axis alignment surface. Therefore, the direction parallel to a C-axis orientation surface can also be utilized as a magnetic path direction.

To exhibit a high permeability in at least two directions parallel to the C-axis alignment plane and orthogonal to each other means that the anisotropy of the permeability in the backward inward direction is small. According to the related structure, the hexagonal Z-type ferrite sintered compact with small anisotropy of permeability and high design freedom can be provided. More preferably, the permeability in 100 kHz of a direction parallel to a C-axis orientation plane is 10 or more. Moreover, as for the permeability of the direction parallel to a C-axis orientation plane, it is more preferable that it is 8 or more at 100 MHz.

Moreover, it is preferable that the said hexagonal Z-type ferrite sintered compact has a machining surface. By having a machining surface, it becomes the structure by which the part by which the orientation of the sintered compact edge part was distorted was removed, and contributes to the high permeability and the variation of permeability.

Moreover, the manufacturing method of the hexagonal Z-type ferrite sintered compact of this invention is a shaping | molding process of shape | molding hexagonal Z-type ferrite powder whose specific surface area is in the range of 800-4000 m <^2> / kg in a uniaxial magnetic field, and obtaining said molded object, and the said It has a baking process which sinters a molded object, It is characterized by the above-mentioned. According to the related method, a hexagonal Z-type ferrite sintered compact having a high permeability and a low anisotropy of permeability can be provided.

In the method for producing a hexagonal Z-type ferrite sintered body, it is preferable that the hexagonal Z-type ferrite powder is mixed with water to form a slurry, and the concentration of the hexagonal Z-type ferrite powder in the slurry is 70 wt% or less. desirable. According to this structure, higher orientation can be implement | achieved. The concentration is more preferably 65 wt% or less.

In the method for producing a hexagonal Z-type ferrite sintered compact, it is preferable to form the hexagonal Z-type ferrite powder after stirring while applying a magnetic field in a mold cavity. According to this structure, a higher orientation can be implement | achieved.

Moreover, in the manufacturing method of the said hexagonal Z-type ferrite sintered compact, it is preferable that the said hexagonal Z-type ferrite powder is obtained by grinding the hexagonal Z-type ferrite sintered compact. The related hexagonal Z-type ferrite powder is advantageous in that it is easy to orientate since there are few abnormalities and crystal grains are sufficiently grown.

According to the present invention, a hexagonal Z ferrite having a particularly high permeability in a specific direction and having a high permeability in a direction other than this direction and having excellent balance of permeability can be provided, and a manufacturing method thereof. By using the ferrite sintered body of the present invention, it is also possible to provide high quality choke coils, inductors, and radio wave absorbers.

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated concretely by embodiment, this invention is not limited to this embodiment.

The ferrite sintered compact used as a raw material of the present invention can be produced according to the usual powder metallurgy method applied to ferrite production except as specifically defined in the present invention. Typical powder metallurgy is as follows.

For example, calcined powder is obtained by mixing the raw materials with a wet ball mill and calcining using an electric furnace or the like. Moreover, the obtained calcined powder is pulverized using a wet ball mill etc., the obtained pulverized powder is shape | molded by a press machine, for example, it bakes using an electric furnace etc., and a hexagonal Z-type ferrite sintered compact is obtained.

In this invention, the grinding | pulverization powder used for the said shaping | molding is produced as follows, for example. The sintered compact obtained as mentioned above is pulverized using a jaw crusher, a disk mill, or the like to obtain a coarse powder. The obtained coarse powder is pulverized using a vibration mill, a ball mill, a jet mill, or the like to obtain fine powder. Water is added to the obtained fine powder to make a slurry, and it presses, applying a magnetic field, using the metal mold | die designed to attract magnetic flux to a molding space. After drying the obtained molded object, it is re-sintered and a ferrite sintered compact is obtained. This manufacturing method is mentioned later in detail.

Hereinafter, the hexagonal Z-type ferrite sintered compact which concerns on this invention is demonstrated concretely.

Hexagonal Z-type ferrite is typically represented by Ba ₃ Co ₂ F ₂₄ O ₄₁ . A hexagonal Z-type ferrite sintered compact is a sintered compact containing such a hexagonal Z-type ferrite phase. A part of barium (Ba) may be replaced with Sr, or a part of cobalt (Co) may be partially substituted with at least one of copper (Cu), zinc (Zn), and nickel (Ni). In the hexagonal Z-type ferrite sintered body, abnormalities such as hexagonal ferrite phases (W phase, Y phase, M phase), spinel phase, and BaFe ₂ O ₄ phase other than the Z phase may be included in part.

In addition, the hexagonal Z-type ferrite sintered body has BaO, CoO, Fe ₂ O ₃ as a main component, and its composition is Ba-rich composition than the stoichiometric composition Ba ₃ Co ₂ Fe ₂₄ O ₄₁ of hexagonal Z-type ferrite It is preferable. It can be considered that abnormality occurs when the stoichiometric composition deviates from Ba ₃ Co ₂ Fe ₂₄ O ₄₁ , but a BaFe ₂ O ₄ phase is easily generated in a Ba rich composition. The BaFe ₂ O ₄ phase contributes to the improvement of the density of the sintered compact, and since the BaFe ₂ O ₄ phase is a nonmagnetic layer, the BaFe ₂ O ₄ phase does not significantly affect the orientation. Therefore, since the sintered compact can be improved while maintaining high orientation, the Ba-rich composition is very suitable for obtaining hexagonal Z-type ferrite having a high permeability.

To to obtain a high sintered density, mainly composed of 17 ~ 21 mol% of BaO, 6 ~ 13 mol% of CoO, the balance of Fe ₂ O ₃ is preferred. Further, it is preferable that with respect to the main component, containing a lithium (Li), 0.05 ~ 1.0% by weight in terms of Li ₂ CO _3. The main component composition range and the content of Li are very suitable for increasing the density of the sintered compact.

Moreover, you may contain Li and silicon (Si) more complex. When containing Li together with Si, the synergistic effect of the sintered compact density improvement and permeability improvement peculiar to it can be acquired. Si exhibits the effect of complex inclusion with Li and an increase in the volume resistivity even in a small amount, but this substantive effect is not exerted at less than 0.05 mass% in terms of SiO ₂ , while the volume resistivity is not improved when exceeding 0.5 mass%. At the same time, the permeability and the sintered compact are lowered, so the range of 0.05 to 0.5 mass% is preferable. By containing Si in the above range in combination with Li, the initial permeability improvement effect by Li can be exhibited while the sintered compact density is 4.95 × 10 ³ kg / m ³ or more and the volume resistivity is 10 ⁴ Ω · m or more. . Further, in order to increase volume resistivity, it may be bivalent in terms of containing a manganese (Mn) of manganese (Mn ₃ O ₄₎ Oxidation 0.05 ~ 5% by weight as the metal ion.

Next, the structure of the hexagonal Z-type ferrite sintered compact which concerns on this invention is demonstrated in detail. In the hexagonal Z-type ferrite sintered body which concerns on this invention, it has the following orientation.

X-ray diffraction is performed on the specific surface of the sintered compact, and the degree of orientation is determined as follows. First, in the one-plane X-ray diffraction pattern of the hexagonal Z-type ferrite sintered body, the integral intensity sum of all diffraction peaks derived from the hexagonal Z-type ferrite included in the measurement range of 2θ = 20 to 80 ° is taken, and ΣI ( HKL), and the sum of integrated intensity of diffraction peaks of all (HK0) planes of L = 0 included in the above range is taken as ΣI (HK0).

That is, ΣI (HKL) is an integral of the diffraction peaks of hexagonal Z-type ferrites over 2θ of 20 ° to 80 °. In addition, I (HKL) represents the integral intensity of the diffraction peaks from the lattice plane represented by the index (HKL). Here, as the I (HKL), when the peak angle of the diffraction line on the (HKL) plane is θ (HKL), an integral value in the range from θ (HKL)-0.4 ° to θ (HKL) + 0.4 ° is used. Doing.

It defines the degree of orientation fc _⊥ from the, ΣI (HKL), and ΣI (HK0). The degree of orientation fc _⊥ is given by fc _⊥ = ΣI (HK0) / ΣI (HKL). It is the degree of orientation fc _⊥ is greater, that is, the greater the ΣI (HK0) of the molecule, in the surface, which conduct X-ray diffraction, and means that if the c-axis is the art there are many crystal grains toward the direction. Among the hexagonal Z-type ferrites, in the composition represented by Ba ₃ Co ₂ Fe ₂₄ O ₄₁ , since the direction perpendicular to the C axis (that is, the C plane) becomes an easy magnetization surface, there are many crystal grains whose C axis faces the plane direction. That means that the permeability of the direction perpendicular to the plane increases.

When the orientation degree fc _으로 is 0.4 or more, the permeability in the direction perpendicular to the plane on which the X-ray diffraction is performed becomes particularly high, and it is possible to obtain a permeability of 30 or more at a frequency of 100 kHz, for example. In addition, in this invention, the surface which has a related orientation degree is called C-axis orientation surface. More preferably, when it is 0.45 or more, the structure is very suitable for obtaining 35 or more magnetic permeability. It is also desirable to have a permeability of 30 or more even at 100 MHz. It is preferable that the C axis of more crystal grains faces the surface direction which performs X-ray diffraction. As an ideal state, the state in which the C-axis of all crystal grains face the surface direction in which X-ray diffraction is performed is shown in FIG.

As can be seen from FIG. 1, the C plane of each crystal grain is perpendicular to the plane of X-ray diffraction. In this case, as long as the C plane, which is an easy magnetization plane, is perpendicular to the plane of X-ray diffraction, the permeability increases in the direction perpendicular to the plane of X-ray diffraction, even if the direction of the C-axis is directed. have.

In this case, it is also equivalent to the case where the state of the C-axis is also arranged in a constant direction as shown in Patent Literature 1 in the case of the surface orientation. However, the C plane is parallel in the direction perpendicular to the plane on which the X-ray diffraction is performed, so there is no change in the state of FIG. Will not be. On the contrary, when the C axis is also provided in a constant direction, the permeability of the constant direction is extremely low.

Accordingly, in the present invention, while the C plane is oriented (the C plane is parallel to the direction) in the direction perpendicular to the plane on which the X-ray diffraction is performed as shown in FIG. 1, in the plane direction perpendicular to the direction, The state in which the C-axis faces a random shape is adopted. As such an index, in at least two planes (hereinafter referred to as vertical planes) perpendicular to and perpendicular to the C-axis oriented plane (corresponding to the plane of the above-described X-ray diffraction), X-ray diffraction The orientation degree fc _// computed from fc _// = I (0018) / I110 is employ | adopted, and it takes the structure that the said orientation degree fc _// is 0.3 or more.

The large degree of orientation fc _// indicates that a large number of crystal grains whose C-axis faces in the direction perpendicular to the vertical plane. This ensures that the C-axis is randomly filled by filling at least two planes perpendicular to each other. Such an orientation mode corresponds to the orientation mode of the sintered compact obtained through the shaping | molding which applies a uniaxial magnetic field, ie, the direct-flow static magnetic field of a predetermined direction. By doing in this way, a high permeability can be obtained in the direction parallel to a C-axis orientation plane, without biasing to a specific direction.

While if C-axis orientation by this arrangement maintains the permeability of direction, by the degree of orientation fc _⊥ to a predetermined range, point to increase the magnetic permeability in a direction perpendicular to the plane C-axis orientation, one of the features of the present invention. By the degree of orientation fc _⊥ to 0.4 or more, parallel to the plane C-axis orientation, and, in at least two directions perpendicular to each other, parallel to the C-axis oriented side of the permeability at 100 kHz in the direction perpendicular to the plane C-axis orientation The ratio of permeability at 100 kHz can be made 0.6 or less.

In particular, when high permeability is required, it is preferable to increase the permeability in the direction perpendicular to the C-axis alignment surface with the permeability ratio of 0.4 or less, and further 0.3 or less. On the other hand, by providing the said orientation mode, the said ratio can be made 0.1 or more in at least two directions parallel to a C-axis orientation plane and orthogonal to each other. Also in the ratio with respect to permeability of the direction perpendicular | vertical to a C-axis oriented surface, you may provide the hexagonal Z-type ferrite sintered compact excellent in the balance of permeability as 0.15 or more.

The configuration regarding the ratio of magnetic permeability can be satisfied even at 100 MHz for or in addition to 100 kHz.

It is possible to obtain a magnetic permeability of 8 or more at 100 kHz in a direction parallel to the C-axis alignment plane. By having such a high permeability also in the direction parallel to a C-axis orientation plane, the said direction can also be used sufficiently as a gyro direction.

In addition, it is desirable to have a magnetic permeability of 8 or more even at 100 MHz. In the case of face orientation, it is possible to fill fc _// , 0.3 or more in one plane perpendicular to the C-axis alignment plane (face orientation), but fc _// , 0.3 or more can be filled in two planes perpendicular to each other. There is no.

More preferably, the orientation degree fc _// is made 0.5 or more. In addition, in at least two planes perpendicular to the C-axis alignment plane and perpendicular to each other, fc _// may be 0.3 or more, but for example, three planes that form an angle of 120 °, and more than one plane, fc It is preferable that _// is 0.3 or more. More preferably, fc _// is 0.3 or more in any plane perpendicular to the C-axis alignment plane.

The hexagonal Z-type ferrite sintered body should just have the C-axis orientation surface which satisfy | fills the conditions mentioned above. The related surface may be a sintered compact surface or may be in the sintered compact. When it exists in a sintered compact, it exposes by cutting or grinding a sintered compact, and what is necessary is just to evaluate the said orientation degree.

In the case where the sintered body is a rectangular parallelepiped, for example, X-ray diffraction is performed on one of its surfaces to evaluate the orientation degree fc _⊥ . We can evaluate the orientation degree fc _// on two different surfaces.

Moreover, the hexagonal Z-type ferrite sintered compact which is excellent in a balance with small anisotropy of permeability can also be grasped as follows. That is, the orientation analysis by the reflection electron pattern (EBSP: Electron Back Back Scattering Pattern) in the scanning electron microscope SEM can also be used. In the relevant orientation analysis, since the inclination amount of the C-axis of the grain with respect to the direction perpendicular to the orientation analysis plane of the sintered body can be observed, the orientation state of the grain can be evaluated.

In this orientation analysis

θ _AV = Σθn (θ) / Σn (θ)

Calculate Is the azimuth angle difference between the direction perpendicular to the orientation analysis plane of the hexagonal Z-type ferrite sintered body and the C-axis direction of the hexagonal Z-type ferrite at the measurement point of EBSP, and n (θ) is the angle θ above. Indicates the number of measurement points. In addition, Σθn (θ) and Σn (θ) indicate that θn (θ) and n (θ) for all θ are added to each other in an interval of 0 to 90 °.

By setting the average orientation difference θ _AV to 65 ° or more, the C plane is oriented in a direction perpendicular to the azimuth analysis plane, resulting in a hexagonal Z ferrite having excellent permeability in the direction. In a related case, the C axis is oriented in a direction parallel to the azimuth analysis plane, and the azimuth analysis plane is a C axis orientation plane.

In addition, the average value n _{AV of the} number of measurement points = ΣI (φ) / m (where φ is an angle when the azimuth difference between the projection direction to the azimuth analysis plane in the C-axis direction and the "one straight line" in the azimuth analysis plane is a positive acute angle I (φ) represents the number of measurement points representing the azimuth difference φ, and m represents the divided score between 0 and 90 °.), And the standard deviation SD = {Σ (I (φ) -n _AV ) ² / When the value SD / n _AV divided by m｝ ^1/2 is 0.6 or less, it means that the C-axis is randomly directed in a direction parallel to the C-axis alignment plane.

In addition, said "one straight line" may be arbitrary in the said orientation analysis surface. By doing in this way, high permeability can also be obtained also in the direction parallel to a C-axis orientation surface. In addition, since SD becomes a large value when the number of measurement points becomes large, the index divided by a considerable number n _AV to the average number of measurement points is used as an index so that the results of EBSP analysis of different measurement points can be compared.

n _AV is preferably set to about 4000. By setting the average orientation difference θ _AV to 65 ° or more and SD / n _AV to 0.6 or less, the magnetic permeability in 100 kHz perpendicular to the C-axis alignment plane is set to 30 or more and 100 kHz in the direction parallel to the C-axis alignment plane. It is also possible to make ratio of permeability 8 or more and permeability of the direction parallel to a C-axis orientation plane with respect to the permeability of the direction perpendicular | vertical to a C-axis orientation plane to 0.15 or more. The ratio is more preferably 0.20 or more.

In addition, evaluation of EBSP should just be performed by measuring in 1 micrometer span using the thing of 1 micrometer as a beam diameter. The analysis region may be selected within the range of 0.01 to 0.3 × 10 ⁻⁶ m ² depending on the average particle diameter of the crystal grains so that 40 or more crystal grains are included in the analysis region. However, in the present invention, 0.16 × 10 ⁻⁶ is a general purpose condition. Azimuth analysis is performed by employing an analysis region of m ² .

In order to raise the absolute value of permeability, it is preferable to make the density of hexagonal Z-type ferrite sintered compact into 4.7x10 <^3> kg / m <^3> or more. Since the sintered compact density of 5.0x10 <^3> kg / m <^3> or more obtains permeability of 40 or more, it is more preferable. More preferably, the sintered compact density is 5.1x10 <^3> kg / m <^3> or more. Although an upper limit is not specifically limited, When it is going to make a sintered compact high, it will become easy to produce a big and big particle | grain, and it is preferable to set it as less than 5.25 * 10 <^3> kg / m <^3> .

As described above, hexagonal Z-type ferrite having improved permeability by improving orientation is advantageous in frequency characteristics of permeability as compared with the case where improvement of permeability is achieved by controlling other factors such as composition and structure.

In order to improve the magnetic permeability by controlling other factors, the magnetic anisotropy and the like also change, so that the frequency characteristics deteriorate and the magnetic permeability decreases at a lower frequency.

On the other hand, in the case of improving the permeability by controlling the orientation, the magnetic anisotropy does not change, so the influence on the frequency characteristic is small. Therefore, the hexagonal Z-type ferrite of the present invention is excellent in frequency characteristics, and for example, the permeability value at 1 GHz can be 30% to 80% of the permeability value at 100 MHz.

Moreover, it is preferable to make the average crystal grain diameter of a sintered compact into the range of 4-50 micrometers from the viewpoint of the improvement of the frequency characteristic of permeability. For example, the magnetic permeability (real part of complex permeability) complex permeability the real part μ rate of change of _{1 GHz} at 1 GHz for the _{μ 100 MHz (= 100 × (} Iμ 100 MHz -μ 1 GHz I at 100 MHz) / μ _{100 MHz} ) decreases. It is also possible to make this change rate 40% or less. As a result, a high permeability can be obtained even at a high frequency of about 1 GHz. It is possible to set the value of permeability at 1 GHz to 25 or more.

Here, the grain diameter of the sintered compact is the longest (maximum diameter) of the line segments that can be drawn inside the observed grains, and the longest of the line segments that can be drawn inside the grains perpendicular to the long axis. As a short axis, the average of the short axis and the long axis was made into individual grain size. The average grain size may be obtained by evaluating arbitrary 100 particles and taking these averages.

The hexagonal Z-type ferrite sintered body described above can be obtained, for example, by using the method for producing a hexagonal Z-type ferrite sintered body shown below. That is, the hexagonal Z-shaped hexagonal Z-type ferrite powder having a specific surface area in the range of 800 to 4000 m ² / kg is formed in a uniaxial magnetic field to obtain a molded body, and a sintered hexagonal Z-form through a sintering process of the molded body. A ferrite sintered body is obtained.

Usually, the ferrite powder uses what was finely ground in order to improve sinterability. On the other hand, in the manufacturing method of the hexagonal Z-type ferrite sintered compact which concerns on this invention, the specific surface area of hexagonal Z-type ferrite powder is controlled to 800-4000 m <^2> / kg. This achieves high orientation and high permeability. When the said specific surface area is too small, a sintered compact will not rise and orientation is also low. On the other hand, when a specific surface area is too big | large, orientation will fall and coarse grains will arise easily.

As the molding method, pressure molding, extrusion molding, injection molding or the like can be used, but particularly simple pressure molding is preferable. In the case of pressure molding, the seed field molding method in which the magnetic field application direction and the pressing direction are parallel, or the horizontal field molding method in which the magnetic field application direction and the pressing direction are perpendicular to each other can be used, but the horizontal field molding method is preferable in order to obtain a high orientation.

In addition, orientation is performed by shaping | molding in a magnetic field. As the method of applying the magnetic field, a uniaxial magnetic field, that is, a DC static magnetic field applied in a predetermined direction may be used as described above. An application method in which the angle of application direction of the magnetic field changes in time such as a rotating magnetic field is not suitable. The hexagonal field which concerns on the said invention which is oriented so that the C surface of a crystal grain may become parallel to a magnetic field application direction by applying and shape | molding a uniaxial magnetic field, and the C-axis direction is a random shape in the plane orthogonal to a magnetic field application direction. A positive Z type ferrite sintered body can be obtained.

In addition, although shaping | molding can also be performed by dry shaping | molding using dry powder, in order to improve orientation, it is preferable to carry out by wet shaping | molding using the slurry obtained by mixing hexagonal Z-type ferrite powder with media, such as water. . Although the kind of water as a medium is not specifically limited to this, For example, you may use a constant.

In addition, impurity ions can be reduced by using ion-exchanged water or distilled water. Although the slurry for shaping | molding may be produced by mixing water with dry grinding powder, it is preferable to use the slurry after wet grinding as a slurry for shaping | molding as it is, without going through a drying process. According to such a method, a higher degree of orientation can be obtained.

The slurry concentration, that is, the weight ratio of the hexagonal Z-type ferrite powder in the slurry may be 85 wt% or less. It is because the friction between particles increases when it exceeds 85 wt%, the rotation of the particles is not sufficiently achieved, and the degree of orientation is lowered. For example, the degree of orientation fc _⊥ the viewpoint of obtaining a high orientation, such as 0.5 or more, it is more preferable to form the concentration of hexagonal Z-type ferrite powder in the slurry to less than 70 wt%. The slurry concentration is more preferably 65 wt% or less.

In addition, it is preferable that the said slurry concentration shall be 50 wt% or more. This is because the productivity is lowered by taking a long time for dehydration during molding to less than 50%. In addition, if the hexagonal Z-type ferrite powder is stirred after applying the magnetic field in the mold cavity and then dried, the agglomeration of the hexagonal Z-type ferrite powder can be released to further increase the orientation.

In addition, in the wet forming method by pressurization using a slurry, as a supply method of a slurry, the method of pressurizing and inject | pouring a slurry into a mold cavity during magnetic field application may be sufficient, or the method of applying a magnetic field after putting a slurry into a cavity may be sufficient. The medium in the slurry is removed from the dewatering hole or clearance formed in the cavity when pressurized. Hexagonal Z-shaped ferrite powder, that is, a molded body, after molding is sufficiently subjected to sintering after drying.

The hexagonal Z-type ferrite powder may be obtained by calcining and pulverizing in a powder state as in a normal process, but a method obtained by pulverizing a hexagonal Z-type ferrite sintered body is preferable from the viewpoint of pulverization. In order to orientate, it is preferable that the particle | grains which comprise hexagonal Z-type ferrite powder are single crystals. In this respect, since grain growth is progressing in the sintered compact, when the sintered compact is pulverized, a powder containing a large amount of single crystal particles is easily obtained.

Therefore, the method of pulverizing a hexagonal Z-type ferrite sintered compact and obtaining powder is a powder adjustment method which is very suitable for orientation in a magnetic field. In this case, it is preferable that the average grain size of the hexagonal Z type ferrite sintered compact provided for related grinding | pulverization is 5-200 micrometers.

In addition, although the powder after calcining can be shape | molded using the hexagonal Z-type ferrite powder grind | pulverized like a normal process, also in this case, the average grain diameter of hexagonal Z-type ferrite in the powder after calcining is 5-200 micrometers. Is preferably.

In addition, a method of obtaining a powder by pulverizing a hexagonal Z-type ferrite sintered compact and a method of using hexagonal Z-type ferrite powder obtained by pulverizing the powder after calcining may be used. It is more preferable not to contain a type ferrite phase. The hexagonal M-type ferrite phase exhibits uniaxial anisotropy in which the C-axis is an easy magnetization axis, is oriented in the direction of the uniaxial applied magnetic field, and is different from the orientation state according to the present invention even if the hexagonal M-type ferrite phase is changed into a hexagonal Z-type ferrite phase by sintering. It is because it produces an orientation state (plane orientation).

Here, substantially free of a hexagonal M-type ferrite phase is a peak of hexagonal M-type ferrite with respect to the intensity of the peak (1016) which is the largest peak of the intensity of hexagonal Z-type ferrite in X-ray diffraction. 006) It means that the ratio of the intensity of the peak is 5% or less. Moreover, it is especially preferable that the powder used for shaping | molding is hexagonal Z-type ferrite which does not contain substantially Y-type ferrite and spinel ferrite.

Substantially free of Y-type ferrite and spinel ferrite, the ratio of the intensity of the peak of the Y-type ferrite to the intensity of the peak, which is the largest peak of the hexagonal Z-type ferrite (1016), is 5% or less, It is said that the ratio of the intensity | strength of the peak of 440 of spinel ferrite is 7% or less.

In the hexagonal Z-type ferrite sintered body obtained by molding in a magnetic field as described above, confusion in orientation may occur in the vicinity of the surface. Therefore, by removing the surface by processing, the ratio of the portion having high degree of orientation in the entire sintered body is increased, which is advantageous for obtaining a high permeability. In addition, removing a surface by processing leads to suppressing the dispersion | variation in orientation, and also permeability in a sintered compact. As for the process, at least one part of the sintered compact should just be processed. The surface is removed even in the processing surface by either grinding or cutting.

EXAMPLE

First, Fe ₂ O ₃ , BaCO ₃ , Co ₃ O ₄ are weighed so that the main component composition is in the same proportion as Fe ₂ O ₃ : 70.2 mol%, BaO: 18.8 mol%, CoO: 11.0 mol%, Mn ₃ O ₄ , Li ₂ CO ₃ and SiO ₂ were added to a ratio of Mn ₃ O ₄ : 3.0 mass%, Li ₂ CO ₃ : 0.4 mass%, and SiO ₂ : 0.13 mass%, respectively. 16 hours of mixing. On the other hand for the _{Mn 3 O 4, Li 2 CO} 3, SiO 2 may be added during the grinding to be carried out after the preliminary firing.

Next, this was calcined at 1100 ° C. for 2 hours in the air. This calcined powder was pulverized with a wet ball mill for 18 hours. A binder (PVA) was added to the produced ground powder and granulated. After granulation, compression molding was performed, followed by sintering at 1300 ° C. for 3 hours in an oxygen atmosphere.

The obtained sintered compact was crushed with a jaw crusher and coarsely pulverized with a disk mill to obtain coarse pulverized powder. On the other hand, the powder which grind | pulverized the coarse grind | pulverized powder with the stamp mill, the powder | pulverized grind | pulverized powder obtained by the vibration mill, and the powder which grind | pulverized the powder grind | pulverized with the vibration mill were respectively obtained. At this time, the milling time of the ball mill was changed to obtain powders having different particle diameters (powders 1 to 5). These powders are almost Z-shaped single phase and have an intensity with respect to the peak of Z-type ferrite at the peak of (0012) of the Y-type ferrite, the (006) peak of the M-type ferrite, and the peak of (440) of the spinel ferrite. The ratio was all less than 3%.

Furthermore, the specific surface area of such pulverized powder was evaluated by the gas adsorption method (BET method) using Macsorb Co. Model 1201. Water was added to powders 1 to 5 to obtain a slurry having a powder concentration of 73 wt%, and wet molding was performed in a magnetic field. Here, the molding pressure was 87.5 MPa, and a 848 kA / m magnetic field was applied in the direction orthogonal to the press direction. The obtained molded body was again sintered on the same conditions as said sintering, and the sintered compact density was evaluated by the underwater substitution method. The obtained powder characteristic and the sintered compact density are shown in Table 1.

Grinding method Powder specific surface area (BET value) m ² / kg Sintered Density × 10 ³ kg / m ³ Powder 1 Grinding crushed powder into stamp mill 200 4.2 Powder 2 Grinding coarse powder into vibratory mill (medium grinding powder) 1080 4.6 Powder 3 Grind crushed powder in a ball mill for 2 h50min 2350 5.0 Powder 4 Grinding powder for 4 h in a ball mill 3560 5.2 Powder 5 Grinding powder for 18 h in a ball mill 6450 5.25

From these results, it turns out that the density of the obtained sintered compact improves, so that powder becomes small. Here, in powder 1, the sintered compact strength was insufficient and it was not used, but in powder 5, coarse grains generate | occur | produced and it also confirmed that this was also practically unsuitable.

The sintered compact was produced by changing molding conditions as follows centering on the powders 2, 3, and 4 which can obtain the sintered compact which has a sintered compact density of 4.5x10 <^3> kg / m <^3> or more and excellent strength. Water was added and wet-molded in the uniaxial magnetic field so that it might become a slurry concentration of 73 wt%. Here, the molding pressure was 87.5 MPa, and the magnetic field was applied in the direction that is directly parallel to the press direction. The magnetic field to apply was made into the range of 0-848 kA / m.

The obtained molded body was re-sintered under the same conditions as the above sintering to obtain a cube-shaped sintered body of about 10 mm square. Cutting a cross-section so as to obtain a sample having the direction of the applied magnetic field and sintered in the normal, X-ray diffraction of the cut surface: by carrying out (XRD X ray diffraction) measurement, and evaluating the degree of orientation fc _⊥.

That is, in the X-ray diffraction pattern obtained by performing XRD in the measurement range of 2θ = 20 to 80 °, the sum of the integral intensity values of all the diffraction peaks of the hexagonal Z-type ferrite is ΣI (HKL), and all L = 0 The sum of the integrated intensity of the diffraction peaks of (HK0) was set to ΣI (HK0). _{fc ⊥ = ΣI (HK0) /} ΣI calculated the degree of orientation fc _⊥ from the formula (HKL). On the other hand, I (HKL) is an integrated value in the range from (theta) (HKL)-0.4 degrees to (theta) (HKL) + 0.4 degrees, when the peak angle of the diffraction line of the (HKL) plane is (theta) (HKL).

On the other hand, had a press direction of the cut of the sample cross-section and a magnetic field is applied so as to obtain a cross-section having a direction orthogonal to the direction and the press direction of the normal line with the normal line, and subjected to XRD measurement in such a cut surface, evaluating the fc _{/ /} . These surfaces become two surfaces perpendicular to each other and perpendicular to the cross section having the above-described magnetic field application direction as a normal line. The orientation degree fc _// defined here is a value obtained by dividing the diffraction peak intensity generated from the lattice plane of the exponent (0018) of the Z-type ferrite by the diffraction intensity generated from the lattice plane of the index (110).

Then, as the magnetic field applying direction H direction, and the surface having the magnetic permeability of H direction of the μ _H, H direction of the normal line, like that, and H-plane for pressing direction P direction, μ _P, P-plane, the magnetic field in the case of applying the direction orthogonal with the direction and the press direction is referred to as L direction, μ _L, L-plane.

In addition, the magnetic permeability of one direction of a sample was evaluated by the method demonstrated below. The conceptual diagram is shown in FIG. As shown in this figure, a gap is formed in a ring-shaped high? Ferrite whose permeability is measured in advance, and the coil is wound (hereinafter referred to as a yoke portion). In the present example, Mn-Zn ferrite of µi = 8100 at 100 kHz was used as the yoke portion. Orientated hexagonal ferrites (μ 2.8, 5.7, 12.9), green powder (μ 5, 60), spinel ferrite (μ 4.0, 19.2, 29.3, 32.8) with standard magnetic permeability of 0 to 60 as standard samples. , 50.0, 55.0) were prepared.

As shown in FIG. 2, after processing so that the gap part and the cross-sectional shape of a yoke part may match, it inserted in the gap part and measured the inductance value at 100 kHz. Since the permeability of the standard sample is already known, the relationship between permeability and inductance from 0 to 60 can be obtained by this. The correspondence of permeability and inductance is approximated by the sixth order polynomial to obtain an approximation curve.

Here, the sample whose magnetic permeability to be measured was similarly processed into the gap site | part like FIG. 2, and the inductance L at 100 kHz was measured. Permeability was computed using said approximation curve from the value of obtained inductance L. In the following, this method will be referred to as a gap method.

Tables 2, 3 and 4 show the results of evaluating the XRD and the permeability of the samples prepared by using the powders 4, 3 and 2, changing the applied magnetic field strength to wet molding, and sintering at 1310 ° C.

Moreover, for comparison, the hexagonal Z-type ferrite sintered compact by the conventional dry process was also produced. The conditions to calcination and baking conditions were made the same conditions as the said method. The calcined powder was pulverized with a ball mill for 18 hours, PVA was added to the obtained pulverized powder, granulated, and dry-molded in a magnetic field. The obtained molded product was sintered at 1300 ° C. in oxygen for 3 hours.

The frequency dependence of the magnetic permeability of the obtained hexagonal Z-type ferrite sintered body is shown in FIG. As can be seen from Fig. 3, in the conventional process, the magnetic permeability at 100 kHz is 19.4 and the magnetic permeability at 100 MHz is 16.6 and 20 or less. On the other hand, in the case of the hexagonal Z-type ferrite sintered body having the composition used in the present embodiment, as shown in FIG. 3, the permeability of 100 MHz is slightly decreased with respect to the permeability of 100 kHz.

Table 2 shows the values of the sintered compact density, fc _소결 , fc _// , and permeability at 100 kHz of the sintered compact obtained by changing the applied magnetic field strength in the range of 0 to 848 kA / m. Even when the applied magnetic field is 0, the permeability at 100 kHz is 20 or more, and it can be seen that the permeability is higher than that of the hexagonal Z-type ferrite sintered body by the conventional dry process shown in FIG. 3.

Used raw powder Applied magnetic field strength (kA / m) Sintered Density (× 10 ³ kg / m ³ ) Orientation H direction permeability real part (100kHz) fC _⊥ fC _// H-plane L-plane P-plane Comparative Example 1 Powder 4 0 5.16 0.21 0.52 1.12 23.5 Comparative Example 2 Powder 4 2.5 5.16 0.25 0.38 1.02 22 Comparative Example 3 Powder 4 15.2 5.12 0.24 0.32 1.24 25.5 Example 1 Powder 4 136 5.14 0.41 0.48 1.81 32 Example 2 Powder 4 376 5.16 0.51 0.52 0.89 38.5 Example 3 Powder 4 568 5.16 0.46 0.72 1.11 40 Example 4 Powder 4 848 5.15 0.49 1.46 1.85 41

From Table 2, it can be seen that by applying a magnetic field of 136 kA / m or more, fc _⊥ becomes 0.3 or more, and a high permeability of H direction of 30 or more can be obtained. Specifically, the above fc _⊥ 0.41, permeability was 32 or more.

In addition, the density of the sintered compact of Examples 1-4 was 5.1x10 <^3> kg / m <^3> or more, and all showed the high value of 5.00x10 <^3> kg / m <^3> or more. Further, in Examples 2 to 4 where fc _0.4 is 0.45 or more, a high permeability of 35 or more can be obtained. Particularly, in Examples 3 and 4 in which the applied magnetic field strength is 568 kA / m or more, an extremely high permeability in H direction of 40 or more is obtained. You can get it.

In addition, the orientation degree fc _// in L-plane and P-plane is 0.3 or more, and the c-axis faces random also in the direction orthogonal to the magnetic field application direction (direction parallel to a c-axis orientation plane), and anisotropy of orientation This small hexagonal Z-type ferrite sintered body can be obtained.

In addition, the value of fc _// exceeded the value measured by L-plane in the value measured by P-plane in all the samples.

In the case of molding in a uniaxial magnetic field, in principle, the orientation state in the direction perpendicular to the applied magnetic field is considered to be random and uniform. However, in the case of this embodiment, since the powder of the used sample contains many plate-shaped particles whose C-axis faces the normal direction of the plate surface, the C plane orientation occurs on the P-plane due to the applied pressure during molding. It can be considered that the peak intensity of 0018) is stronger.

Accordingly, in the case of press-molding, in a direction perpendicular to the H direction, the degree of orientation fc _// of P-plane the higher, the degree of orientation in a plane perpendicular to the L-direction fc _// is the smallest. The degree of orientation fc _// of the associated L-plane not to be less than 0.3 indicates that the anisotropy of the orientation is small by that amount. Further, fc _// exhibited both L-plane, P-plane tends to increase with the increase of fc _⊥.

This is because the tendency of the H-plane and the C plane of the crystal becomes stronger as the applied magnetic field strength increases and fc _⊥ increases, so that the diffraction peak of the C plane becomes stronger in the direction orthogonal to the H-plane. Can be. When the applied magnetic field strength is 376 kA / m or more, the L-plane orientation degree fc _// becomes 0.5 or more, and the L-plane orientation degree fc _// ratio with respect to the fc _// orientation of the P-plane is 0.5 or more. do.

Further, when the applied magnetic field is 700 kA / m or more, the degree of orientation fc _// of L-plane is more than 1.0, and the degree of orientation fc _// of L-plane non than 0.7 for the degree of orientation fc _// of P-plane It can be seen that the anisotropy in the direction perpendicular to the magnetic field application direction (direction parallel to the C-axis alignment plane) is further reduced.

Using the powder 3 in Table 3, it showed the samples produced by varying the extent of the magnetic field up to 23.2 ~ 848 kA / m, fc ⊥, a real part of permeability at 100 kHz. In addition, Example 12 is a sample which stirred the raw material powder in a cavity with the stirring rod during the application of a magnetic field before the press molding in a magnetic field.

Used raw powder Slurry concentration (wt%) Applied magnetic field strength (kA / m) Sintered Density (× 10 ³ kg / m ³ ) Orientation fc⊥ (H-plane) Permeability real part (100kHz) μH Example 7 Powder 3 73 23.2 5.06 0.43 31 Example 8 Powder 3 73 136 5.13 0.52 43 Example 9 Powder 3 73 376 5.10 0.52 42.5 Example 10 Powder 3 73 568 5.13 0.62 41 Example 11 Powder 3 73 848 5.11 0.58 40.5 Example 12 Powder 3 73 848 (Stirring) 5.13 0.68 48.5

When using powder 3 having a larger average particle diameter than powder 4, that is, having a specific surface area of 2350 m ² / kg or less, fc _⊥ of 0.4 or more and a permeability of 30 or more even in a magnetic field of 23.2 kA / m Becomes

Further, the embodiment was for example about 11, by gaepbeop, P permeability of the direction and L direction (μ _P, μ _L) is measured, each of 15.5, and a 20.5, in a direction perpendicular to the H direction, the high magnetic permeability of 15 or Indicated. In this case, the ratio of permeability (μ _L / μ _H , μ _P / μ _H ) at 100 kHz is also 0.38 to 0.51, is 0.6 or less, at the same time 0.1 or more, and hexagonal Z type with excellent anisotropy balance. A ferrite sintered body was obtained.

In particular, the degree of orientation is greatly improved by stirring the slurry in the magnetic field, and a high value of 45 or more can be obtained as the magnetic permeability in the magnetic field application direction (H direction). Furthermore, the magnetic field applying direction and a pressing direction, for comparison, but also making the sample by the longitudinal magnetic field molding in the same direction, such a degree of orientation fc _⊥ is, compared to the case of the transverse sheet molding was found to be reduced by up to 0.2 to 0.3 .

The frequency characteristics of the magnetic permeability in one direction of the oriented hexagonal Z-type ferrite, particularly the magnetic permeability at a high frequency of 100 MHz or more, were evaluated by the method described below. That is, since the permeability in the direction parallel to the c plane of the ferrite sintered body oriented in the uniaxial magnetic field cannot be measured simply by the ring sample, the ring annular plane is parallel to the H-plane, P-plane or L-plane. Three ring samples were cut out, and the permeability of the H direction, the P direction, and the L direction was calculated from the permeability measurement results of these ring samples.

Before contacting the evaluation method, the necessary relations are drawn. The longitudinal direction and the lateral direction are defined in the Y direction (for example, P direction) and X direction (for example, H direction) along the plate surface of the magnetic plate having anisotropy, and the difference between the outer diameter and the inner diameter is It is assumed that a sufficiently small ring sample is cut, the coil is wound N times on the ring sample, and a current I is passed through the coil to measure the superpermeability. In addition, the cross-sectional area of a ring sample shall be S.

If θ, r of the ring sample is defined at the origin as shown in Fig. 4, the following relational expression 1 can be obtained.

　　(관계식 1)

(Relationship 1)

는, 링 시료의 접선방향의 미소선소 벡터이다. 또한, 링 시료로부터 자속의 누설이 없는 것으로 하고, 링시료 내부의 자속밀도 벡터의 크기가 일정하다고 하면, 아리와 같은 관계시 2를 얻을 수 있다.here,

Is the micro element vector of the tangential direction of a ring sample. Further, if there is no leakage of magnetic flux from the ring sample, and the magnitude of the magnetic flux density vector inside the ring sample is constant, the relation time 2 similar to Ari can be obtained.

　(관계식 2)

(Relationship 2)

는 링시료내부의 자속밀도 벡터이고,

이다.here,

Is the magnetic flux density vector inside the ring sample,

to be.

If the permeability in the X direction and the permeability in the Y direction are set to μ _x and μ _y , respectively, the following relational expression 3 can be obtained.

　　　(관계식 3)

(Relationship 3)

는 링 시료 내부의 자계 벡터이다. 또한,μ_x 및 μ_y 및 후술의 μ_xyplane는 모두 비투자율이다.here,

Is the magnetic field vector inside the ring sample. _Incidentally , mu _x and mu _y and the mu _xyplane described later are both specific permeability.

From the above relations 1-3 and the law of Anper

(식 4)

(Equation 4)

Relationship can be obtained.

Since the magnetic inductance L is the ratio of the interlinked magnetic flux and the current, using the relationship of (Equation 4),

를 얻을 수 있다.

Can be obtained.

이기 때문에, 링 시료로부터 관측되는 투자율을 μ_xyplane로 두면,In vacuum (μ _x = 1 μ _y = 1)

Since the permeability observed from the ring sample is μ _xyplane ,

(식5)의 관계를 얻을 수 있다.

The relationship of equation (5) can be obtained.

Considering the relationship as shown in (Equation 5), three kinds of ring samples are cut out so that the annular surface becomes H-plane, L-plane, or P-plane, and is 10MHz -1 with an inductance meter 4291B (manufactured by Agilent). The complex relative permeability (μ _{plane H-, L- planee} μ, μ _{P- plane)} to 8GHz were measured. The sample had dimensions of 6.8 mm in outer diameter, 3.2 mm in inner diameter and 1.5 mm in thickness. Permeability in each direction was computed using the following formula from the measured value.

In the following, this method is called a "ring method."

In addition, the following sample was created for comparison, and the permeability etc. of each direction were measured. That is, water was added to powder 2 in Table 1 so as to have a slurry concentration of 73 wt%, and the slurry was placed in a nonmagnetic mold, and rotated three times for each mold in a 480 kA / m static magnetic field. It was molded at a molding pressure of 22 MPa. At this time, the molding pressure was applied in a direction perpendicular to the magnetic field. The obtained compact was sintered at 1350 ° C. in an oxygen atmosphere to obtain a sintered compact (Comparative Example 4).

In addition, the direction in which the magnetic field is applied during pressurization of the molding is the H direction, the direction in which the press direction is orthogonal to both the P direction, the H direction and the P direction is referred to as the L direction, and the surfaces having the respective directions as normal lines are H-plane, It is called P-plane and L-plane.

Table 4 shows the sintered compact densities of Comparative Examples 1 to 4, Examples 1 and 4, the degree of orientation (f _{C ⊥} , f _{C //} ), and the permeability of H, L and P directions in each of 100 MHz determined by the ring method. The value of the real part was shown.

Used raw powder Sintered Density (× 10 ³ kg / m ³ ) Orientation Permeability real part (100MHz) fC _⊥ fC _// H-plane L-plane P-plane μH μL μP Comparative Example 4 Powder 2 4.80 0.74 0.07 － 35.0 27.8 4.0 Comparative Example 1 Powder 4 5.16 0.21 0.52 1.12 15.6 17.6 10.5 Comparative Example 2 Powder 4 5.16 0.25 0.38 1.02 17.4 17.3 10.7 Comparative Example 3 Powder 4 5.12 0.24 0.32 1.24 17.9 14.7 11.3 Example 1 Powder 4 5.14 0.41 0.48 1.81 24.9 13.9 9.6 Example 4 Powder 4 5.15 0.49 1.46 1.85 37.7 11.5 9.1

Comparison of Example 4 fc _// of P-plane is, I (0018) and is very strongly observed, could not be evaluated hidden by the diffraction peak of the diffraction peak (0018) plane of the face (110), the fc _// 0.3 It was clear over. In addition, it is understood that fc _{에서 의} in the H-plane is 0.7 or more, and a high value of 35 in the H direction at 100 MHz is obtained.

On the other hand, fc _// in L-plane is, and the smaller value of 0.1 or less, as compared with fc _// of P-plane is small, it was confirmed that the heading is concentrated in H-plane in the c-axis direction specific. In this case, the magnetic permeability in the P direction is a low value of 4 or less.

In Comparative Examples 1 to 3 where the applied magnetic field strength was low and the orientation degree fc _⊥ was less than 0.4, the ratio (μ _L / μ _H , μ _P / μ _H ) of the magnetic permeability at 100 MHz exceeded 0.6, and _H was changed by the orientation. It can be seen that the permeability of the direction is not high enough.

On the contrary, in Example 1, the degree of orientation fc _⊥ 0.4 or more, a ratio _{(μ L / μ H, μ} P / μ H) of the magnetic permeability is 0.39 ~ 0.56, and 0.6, and at the same time represents a value above 0.1.

In Example 4, fc _// is 1.4 or more in both L-plane and P-plane, and the C axis is random in the direction perpendicular to the magnetic field application direction (the direction parallel to the c-axis alignment plane). The hexagonal Z-type ferrite sintered compact with small anisotropy of orientation in an orientation surface can be obtained. As a result, the L direction, the magnetic permeability μ _L, the magnetic permeability μ of the _P-P direction is 11.5 and 9.1 respectively, were all confirmed that the high value of more than 8. The permeability in the H direction also shows a high value of 35 or more. Further, in the L direction, the magnetic permeability μ _L, the magnetic permeability of the P direction μ _P, H direction, that is the ratio of a magnetic permeability μ _H in the direction perpendicular to the plane C-axis orientation, it has 0.31, 0.24, and all of not more than 0.4, At the same time, it exhibits a high value of 0.15 or more, and it is understood that the balance of permeability anisotropy is excellent.

It showed a value of μ _H obtained from fc _⊥, gaepbeop, the sintered density of a sample prepared by using the powder 2, in Table 5.

Used raw powder Slurry Concentration (%) Approved magnet strength (kA / m) Sintered Density (× 10 ³ kg / m ³ ) Orientation fC _⊥ Permeability real part (100 kHz) H-plane μH Example 13 Powder 2 73 136 4.59 0.55 35 Example 14 Powder 2 73 848 4.60 0.61 31

It is understood that in Examples 13 and 14, the degree of orientation is 0.5 or more by applying a magnetic field of 136 kA / m or more, and the permeability is 30 or more. In addition, when using powder 2 having a specific surface area smaller than that of powder 3 and having a specific surface area of 1080 m ² / kg or less, the orientation degree fc _⊥ is increased when compared with the case of using powder 3 at the same applied magnetic field strength. Able to know.

From the results of Table 2-4 with the powder 2 to 4, it can be seen that the smaller the specific surface area of the hexagonal Z-type ferrite powder providing a molding with high orientation fc _⊥. However, although the density of sintered compact is 4.5x10 <^3> kg / m <^3> or more, although it becomes slightly low, permeability is suppressed by that much. For example, in Examples 2 and 8, fc _⊥ = 0. As the magnetic permeability of 38 or more is obtained even at about 5, it can be seen that when the sintered compact density is 4.7 × 10 ³ kg / m ³ or more, a higher permeability is more easily obtained.

Next, the sintered compact sample was produced like the sample of Example 11 except having adjusted the slurry concentration to 68%, and shape | molding without drying the slurry after grinding | pulverization (Example 15). Moreover, the sintered compact sample was produced on the conditions different only from a related sample and a main component composition (Example 16). The main component compositions of Example 16 were Fe ₂ O ₃ : 70.6 mol%, BaO: 17.6 mol%, CoO: 11.8 mol%, and a stoichiometric composition of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ .

Table 6 shows the results of evaluating the real parts of the magnetic permeability at sintered compact density and orientation degree _fcPa and 100 kHz in Examples 15 and 16. Permeability, on the other hand, is measured by the gap method.

Used raw powder Slurry concentration (wt%) Applied magnetic field strength (kA / m) Sintered Density (× 10 ³ kg / m ³ ) Orientation fc _⊥ (H-plane) Permeability real part (100kHz) μH Example 15 Powder 3 68 848 5.14 0.70 55.0 Example 16 Powder 3 68 848 4.95 0.74 40.0

As shown in Table 6, even in the sample of Example 16 having a stoichiometric composition, a high orientation of 0.7 or more and a high permeability of 40 or more can be obtained. On the other hand, in Example 15 which has a composition which is Ba rich rather than stoichiometric composition, the sintered compact density improves 3% or more. On the other hand, the degree of orientation of Example 15 remains slightly lower than that of Example 16. As a result, the permeability can be improved by 30% or more, and a permeability of 50 or more can be obtained. Accordingly, it can be seen that a Ba-rich composition is more suitable for achieving higher density and higher permeability of the oriented hexagonal Z-type ferrite than the stoichiometric composition.

In addition, compared with the sample of Example 11, the sample of Example 15 has significantly improved both the degree of orientation fc _⊥ and the permeability, and it can be seen that it is particularly effective to improve the orientation by using the slurry after wet grinding without drying the slurry. .

About the sample of Example 15, the real part (mu) _H , (mu) _L , (mu) _P of permeability of H, L, and P directions in 100 kHz was evaluated by the gap method, respectively, and it was 55.0, 21.0, and 12.5, respectively. In the direction perpendicular to the C-axis alignment plane, even at 100 kHz, a very high permeability of 50 or more can be obtained. In addition, even in a direction parallel to the C-axis alignment plane, a high permeability of 10 or more can be obtained, and the ratio () of the permeability is also 0.23 to 0.00. Hexagonal Z-type ferrite sintered compact having a balance of 38, 0.4 or less and 0.01 or more and excellent in anisotropic balance was obtained.

Further, by ringbeop, I evaluated the H, L, P real part of magnetic permeability in all directions μ _H, μ _L, μ _P at 100MHz, respectively, 51.5, 11.8, 8. 1. In the direction perpendicular to the C-axis alignment plane, even at 100 MHz, a very high permeability of 50 or more can be obtained. In addition, even in a direction parallel to the C-axis alignment plane, a high permeability of 8 or more can be obtained, and the ratio of permeability (μ _L / μ _H , μ _P / μ _H ) is also 0.16 to 0.23, and simultaneously 0.1 to 0.4 or less. As mentioned above, it turns out that the outstanding characteristic is exhibited also in 100 MHz.

Next, the sample was produced like Example 15 except having calcined at 1330 degreeC in oxygen for 3 hours, and calcining powder for 22 hours and providing it for shaping | molding (Example 17). A sintered body density, the degree of orientation fc _⊥, results of evaluation of the permeability at 100 kH real part of the resultant samples are shown in Table 7. Permeability is measured by the gap method.

Slurry concentration (wt%) Applied magnetic field strength (kA / m) Sintered Density (× 10 ³ kg / m ³ ) Orientation fc _⊥ (H-plane) Permeability real part (100kHz) μH Example 17 68 848 5.05 0.66 42.0

Instead of pulverizing the sintered body, by adopting a step of growing sufficiently by raising the plasticization temperature and extending the plasticizing time, an orientation degree of fc _이상의 of 0.4 or more was obtained.

Next, the crystal | crystallization which exists in the c-axis orientation plane (H-plane) which is an observation surface about the sample (comparative example 1, Example 1, 2, 8) of some of the samples of Tables 2-4. The orientation of the particles was measured by EBSP (TSL, OIM ™ 4.0).

The observation magnification was selected so that at least 40 or more crystal grains were included in the observation area of EBSP. The observation area was 200 μm × 800 μm (0.16 × 10 ⁻⁶ m ³ ), and the step spacing of the beam was 1 μm. Based on the azimuth information obtained from each measurement point, the azimuth angle difference between the c-axis direction of the crystal and the vertical direction of the sample plane (observation surface) is obtained for each point, and the number of points having the same azimuth angle difference θ is counted, and n Azimuth difference distribution of (theta) was obtained as (theta) as a vertical axis. The obtained orientation difference distribution chart is summarized in FIG.

The results shown in FIG. 5 show that the distribution in the C-axis direction is concentrated in a direction parallel to the C-axis orientation plane (H-plane) as the orientation degree fc _⊥ is improved. From the obtained orientation difference distribution, the C-axis average orientation difference θ _AV of the crystal was calculated using (Equation 1). The results are shown in [Table 8].

Used raw powder Slurry concentration (wt%) Applied magnetic field strength (kA / m) Orientation fc _⊥ Permeability real part (100kHz) θAV (°) SD / nAV Comparative Example 1 Powder 4 73 0 0.21 23.5 57.1 0.44 Example 1 Powder 4 73 136 0.41 32 68.1 0.36 Example 2 Powder 4 73 376 0.51 38.5 72.3 0.45 Example 8 Powder 3 73 848 0.68 48.5 74.4 0.21

When the degree of orientation fc _⊥ is more than 0.4, and the average c-axis orientation by more than θ _AV is 65 °, it can be seen that the C axis is C-axis oriented in parallel with the side closer. At the same time, the permeability of 100 kHz in the gap method is 30 or more. Furthermore, when the degree of orientation fc _⊥ is improved to 0.5 or more is realized scent C axial average orientation difference θ _AV is more than 70 ° gobae. In Examples 2 and 8, it becomes clear that (theta) _AV becomes 72.3 degrees and 74.4 degrees, and becomes closer to parallel to a C-axis orientation plane. When θ _AV is 70 ° or more, the permeability of 100 kHz in the gap method is 35 or more.

Let φ be an angle when the azimuth difference between the projection direction to the observation plane in the C-axis direction and one straight line in the observation plane is a positive acute angle, and the result of taking φ on the horizontal axis and I (φ) on the vertical axis 6 is shown.

From Fig. 6, all of Comparative Examples 1, 1, 2, and 8 are in the same tendency, and a slight deflection can be seen in the distribution of I (φ) due to φ, but the strongest observation score exceeds 20000 points. Compared with the case of 5, the value is 7000 points or less even in the direction in which the c-axis direction is observed most strongly in FIG. The ratios are all 0.6 or less in the Example, and the degree of deflection is low.

Here, Table 8 also shows the value of SD / n _AV obtained by dividing SD calculated in (Equation 3) by n _AV calculated in (Equation 2). The value of SD / n _AV can be used as an index of dispersion, and is also 0.6 or less in Comparative Examples 1, 1, 2, and 8, and it is confirmed that the projection direction of the C-axis to the C-axis alignment plane does not show strong deflection. It became. In addition, in Example 8, SD / n _AV is especially 0.21 or less, and the projection direction of the C-axis to the C-axis alignment plane is randomly distributed in-plane.

It showed a value of the degree of orientation fc _⊥, when magnetic permeability of Table 9 in using the powder 4, and a constant magnetic field is 848 kA / m, In other molding the slurry concentration. It turns out that orientation degree improves when slurry concentration falls. When the slurry concentration is 65 wt% or less, fc _⊥ becomes 0.6 or more, and a high permeability of more than 40 can be obtained.

Used raw powder Slurry concentration (wt%) Applied magnetic field strength (kA / m) Sintered Density (1 × 0 ³ kg / m ³ ) Orientation fc⊥ (H-plane) Permeability real part (100kHz) μH Example 4 Powder 4 73 848 5.15 0.49 41 Example 5 Powder 4 65 848 5.22 0.60 40 Example 6 Powder 4 60 848 5.18 0.71 44

In FIG. 7, 100 MHz-1. of the complex permeability calculated | required by the ring method of Example 4. Frequency characteristics up to 8 GHz were shown. It can be seen from FIG. 7 that the real part of the complex permeability in the H direction is 30 or more up to 1 GHz, and a high permeability is maintained. Permeability of _{1 GHz} μ _{1 GHz} maintains 80% or more of _{100 MHz} permeability μ _{100 MHz} , and the rate of change (= 100 × (| μ _{100 MHz} -μ _{1 GHz} |) / μ _{100 MHz} is 20% and 40% It becomes the following small value.

As described above, the present invention can provide a hexagonal Z-type ferrite having a particularly high permeability in a specific direction and having a high permeability in a direction other than this direction and having excellent balance of permeability, and a manufacturing method thereof. . And by using the ferrite sintered compact of this invention, a high quality choke coil, an inductor, an electromagnetic wave absorber, etc. can also be provided.

1 is a conceptual diagram showing a state in which the C axis of the crystal grains faces the observation plane direction;

2 is a conceptual diagram illustrating a measuring method of a gap method.

3 is a diagram showing the frequency dependence of the magnetic permeability of a hexagonal Z-type ferrite sintered body by a conventional dry process.

4 is a diagram showing definitions of r, θ and line elements in a ring sample.

5 is a diagram illustrating a distribution of azimuth differences between a C-axis orientation and a sample plate vertical direction.

Fig. 6 is a diagram showing a distribution of azimuth difference between a direction in which the C-axis direction is projected on the sample plate surface (observation surface) and a specific direction in the sample plate surface (observation surface).

7 is a diagram showing frequency characteristics of complex permeability in the H, L, and P directions of Example 4;

Claims (12)

Hexagonal Z-type ferrite sintered body, in the X-ray diffraction pattern having a measurement range of 2θ = 20 to 80 °, the hexagonal Z-type is obtained when I (HKL) is the integral intensity of the diffraction peak represented by the exponent (HKL). When the sum of integrated intensity of all diffraction peaks of ferrite is ΣI (HKL) and the sum of integrated intensity of diffraction peaks of all (HK0) where L = 0 is ΣI (HK0), The orientation given by fc _⊥ = ΣI (HK0) / I (HKL) also has a C-axis orientation plane with fc _⊥ greater than or equal to 0.4, and at least on at least two planes perpendicular to the C-axis orientation plane and perpendicular to each other, A hexagonal Z-type ferrite sintered body, wherein the orientation degree fc _// calculated from fc _// = I (0018) / I (110) of 0.3 is 0.3 or more. Hexagonal Z-type ferrite sintered body, which has a C-axis orientation plane in which the average orientation difference represented by θ _AV = Σθn (θ) / Σn (θ) is 65 ° or more in orientation analysis by EBSP (Electron Back Scattering Pattern). , the mean value of the number of measurement points given by n _AV = ΣI (φ) / m, and the standard deviation SD given by SD = (ΣI (φ) -n _AV ) ² / m} ^1/2 divided by SD / n _AV = 0.6 A hexagonal Z-type ferrite sintered body which is the following. (Theta: θ: azimuth angle difference between the direction perpendicular to the orientation analysis plane of the hexagonal Z-type ferrite sintered body and the C-axis direction of the hexagonal Z-type ferrite at the measurement point of EBSP, n (θ): number of measurement points representing θ, Σθn (θ): Sum of θn (θ) plus one another in a range from 0 to 90 °, Σn (θ): Sum of n (θ) plus one another in a range from 0 to 90 °, φ: Angle when the azimuth difference between the projection direction to the azimuth analysis plane in the C-axis direction and one straight line in the azimuth analysis plane is a positive acute angle I: number of measurement points indicating azimuth difference φ, m: The score is divided between 0 and 90 °.) The method according to claim 1 or 2, The hexagonal Z-type ferrite sintered body includes BaO, CoO, Fe ₂ O ₃ as a main component, and the composition is Ba rich than the stoichiometric composition Ba ₃ Co ₂ Fe ₂₄ O ₄₁ of the hexagonal Z-type ferrite. Hexagonal Z-type ferrite sintered body. The method according to any one of claims 1 to 3, Hexagonal Z-type ferrite sintered body, characterized in that the sintered body density is 5.0 × 10 ³ kg / m ³ or more The method according to any one of claims 1 to 4, Permeability μ _의 in the direction perpendicular to the C-axis alignment plane and at least two directions parallel to the C-axis alignment plane and orthogonal to each other when the permeability in the direction parallel to the C-axis alignment plane is μ _// . A hexagonal Z-type ferrite sintered body, wherein the ratio μ _// / μ _⊥ is 0.6 or less at 100 kHz and / or 100 MHz with respect to the magnetic permeability μ _// . The method according to any one of claims 1 to 5, A hexagonal Z-type ferrite sintered compact having a magnetic permeability of 100 or more at 100 kHz perpendicular to the C-axis alignment plane. The method according to any one of claims 1 to 6, Hexagonal Z-type ferrite sintered compact having a permeability of 8 or more at 100 kHz in a direction parallel to the C-axis alignment plane The method according to any one of claims 1 to 7, The hexagonal Z-type ferrite sintered body has a machined surface, wherein the hexagonal Z-type ferrite sintered body. Preparation of hexagonal Z-type ferrite sintered body having a molding process of molding a hexagonal Z-type ferrite powder having a specific surface area in the range of 800 to 4000 m ² / kg in a uniaxial magnetic field to obtain a molded body, and a sintering process of the molded body. Way. The method of claim 9, The hexagonal Z-type ferrite sintered body is mixed with water to form a slurry, and the hexagonal Z-type ferrite sintered body is molded at a concentration of 70 wt% or less in the slurry. The method of claim 10, A method of manufacturing a hexagonal Z-type ferrite sintered body, wherein the hexagonal Z-type ferrite powder is stirred while applying a magnetic field in a mold cavity, followed by molding. The method according to any one of claims 9 to 11, The hexagonal Z-type ferrite powder is obtained by pulverizing a hexagonal Z-type ferrite sintered body, wherein the hexagonal Z-type ferrite sintered body is produced.

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