JP2003342062A - Mn-Zn-BASED FERRITE SINTERED COMPACT AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Mn-Zn-based ferrite sintered compact showing only a small amount of distortion of an output wave form to an input wave and excellent in THD characteristics, and to provide a method for producing the same. <P>SOLUTION: The number of holes in crystal grains is 40% or less relative to the total number of holes in the Mn-Zn-based ferrite sintered compact composed mainly of Fe<SB>2</SB>O<SB>3</SB>, ZnO and manganese oxide. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Mn-Zn type ferrite sintered body used for a transmission transformer and a filter of a communication device for xDSL, and particularly, there is little waveform distortion generated when a signal passes through a magnetic core, Mn- with excellent THD characteristics
The present invention relates to a Zn-based ferrite sintered body and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a Mn--Zn ferrite sintered body having a high magnetic permeability has been used as a magnetic core in various transformers and filters, but a magnetic core used in electronic parts for communication equipment such as an xDSL modem has a high magnetic permeability. In addition to the magnetic susceptibility, it is required that the waveform distortion that occurs when a communication signal passes through an electronic component for communication equipment is small.

[0003]

SUMMARY OF THE INVENTION ADSL (Asymmetric Metric Dig) especially for high-speed and large-capacity communication
In the magnetic core used in the communication device for xDSL represented by ital Subscriber Line),
Since the distortion of the signal waveform that occurs when the signal passes causes an increase in the error rate during information transmission, it is required to further reduce the waveform distortion when the signal is output. It is required to improve the characteristics of

For example, the distortion of the output waveform that occurs when a signal passes through the magnetic core is caused by the fact that the output fundamental wave contains a harmonic component centered on the third harmonic of the input fundamental wave. It is considered that this is due to the non-linearity / hysteresis curve characteristics of the magnetic field H and the magnetic flux density B. Practically, the linearity is improved by providing a gap in the magnetic core for the distortion of the output waveform and reducing the effective magnetic permeability.
It is currently used as a communication transformer.
However, such a method has not been able to substantially improve the linearity of the BH loop such as reduction of coercive force, and has a problem that a load of increasing the number of windings is required to obtain a required inductance. Therefore, further distortion reduction is required by improving the magnetic core itself used in the xDSL communication device.

The present invention has been found as a result of extensive studies to solve the above problems, and is a Mn-Zn ferrite sintered body excellent in THD characteristics and having a small output waveform distortion with respect to an input wave, and its production. The purpose is to provide a method.

[0006]

A first invention is Fe ₂ O.
₃ , Mn-Z containing ZnO and manganese oxide as main components
An n-based ferrite sintered body, which is 40% or less of the total number of holes in the Mn-Zn-based ferrite sintered body and has excellent THD characteristics and excellent THD characteristics. It is a sintered body. In the present invention, it is 52.0 to 54.0 mol% in terms of Fe ₂ O ₃ , and 18.0 in terms of ZnO.
˜25.0 mol%, with the balance manganese oxide as the main component, and 0 to 0.2 wt% (excluding 0) of Ca in terms of CaO as subcomponents and 0 to 0.01 wt% (0 in terms of SiO ₂ ).
It is preferable to contain Si). M of the present invention
In the n-Zn-based ferrite sintered body, THD / μa represented by the ratio between the THD value and the amplitude magnetic permeability μa is −135 dB or less in the maximum magnetic flux density of 30 mT, the frequency of 5 kHz, and the temperature range of 0 ° C. to 85 ° C. You can do it.

The second invention is that the sintering atmosphere is set to an oxygen partial pressure of 5%.
Of an Mn-Zn-based ferrite sintered body excellent in THD characteristics in which the sintering temperature is set to 1300 ° C. to 1380 ° C. and the number of pores in the grain of the sintered body is 40% or less of the total number of pores It is a manufacturing method. In the present invention, the rate of temperature increase from 1000 ° C to the sintering temperature is preferably 5 ° C / hour to 150 ° C / hour.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The THD / μa used as an index indicating the distortion amount of the output waveform in the present invention will be described. TH
D (Total Harmonic Distorti
on total harmonic distortion) is the ratio of the harmonic component Vh (V) to the fundamental wave Vb (V) and is given by the following equation: THD = 20 × LOG ₁₀ (Vh / Vb) [dB] Also, THD / μa is given by the following equation. THD / μa = 20 × LOG ₁₀ ((Vh / Vb) / μ
a) [dB] Here, μa is the amplitude permeability. The value obtained by dividing the ratio of the harmonic component by μa is used as an index of distortion, for example, Pr.
ocedings of the Eight I
international Conference o
n Ferrite, 509, 2000,
This is because the evaluation peculiar to the material is performed excluding the influence of μa change due to gap formation or the like on THD. This THD /
By using μa as an index, the evaluation in the toroidal shape used for material evaluation and the evaluation in the shape of the actual product can be correlated.

In the present invention, in order to further eliminate the influence of factors such as the number of windings, the circuit resistance, and the inductance, the following Distortion of Transform is performed.
The rmer Coefficient (DTC) was also used.

[0011]

[Equation 1]

Then, the THD _F characteristic obtained by the above DTC and THD / μa and obtained by the following equation is also shown as an index of the magnetic core characteristic. This makes it possible to evaluate the magnetic core characteristics while eliminating the influence of the shape and specifications of the actual product as much as possible. THD _F = THD / μa + 20 × LOG ₁₀ (1 / DT
C) [dB] Here, it is shown that the smaller the THD / μa and THD _F, the smaller the distortion amount of the output waveform. The frequency used by ADSL is 20 kHz to 1.1 MHz, but the audio analyzer used for THD measurement covers only a part of the low frequency side of the frequency range, and sufficient accuracy can be obtained even in this range. In the present invention, the frequency is set to 5 for convenience of measurement of THD / μa.
It was set to kHz.

Although the value of THD / μa increases as the maximum magnetic flux density increases, it is set to 30 mT in the present invention from the level of practical use. That is, THD / μa
Since the value of is different from the measurement frequency and the magnetic flux density and is not unambiguous, the THD / μa value in the present invention is the value under the above-mentioned measurement conditions and is used as the standard for material evaluation. In addition, the evaluation of THD / μa in the present invention was set to 0 ° C. to 85 ° C. from the operating environment temperature of the ADSL modem. Frequency 5kHz,
By setting the magnetic flux density to -135 dB or less (corresponding to -114 dB or less in THD _F ) under the measurement conditions of the maximum magnetic flux density of 30 mT, the error rate of information transmission in an actual device is improved, and practically sufficient and high transmission characteristics can be provided.

The Mn-Zn ferrite sintered body according to the present invention is characterized in that the number of voids in the grain of the sintered body is 40% or less of the total number of voids. It is preferable that there are few voids that are defects in the sintered body, but it is difficult to completely remove such voids in the actual manufacturing process of the Mn—Zn ferrite sintered body. The presence of such holes is considered to cause a decrease in the density and saturation magnetization of the sintered body and deteriorate the soft magnetic properties such as the initial permeability.
As a result of extensive studies on the relationship with the D characteristic, the present invention has been achieved. That is, among the above-mentioned vacancies, there are vacancies existing at the grain boundaries and vacancies existing inside the grains, but the number of vacancies within the grains should be reduced to 40% or less of the total number of vacancies. The THD characteristics are remarkably improved in the room temperature range (25 ° C)
It becomes possible to obtain a good THD / μa value of 140 dB or less. In order to obtain a better THD characteristic, it is more preferably 25% or less, further preferably 15%.
% Or less. It is not always clear why the reduction of intragranular vacancies improves THD characteristics, but it is considered that intragranular vacancies act as pinning sites for domain walls. Through improving sex
It is presumed that it contributes to the improvement of HD characteristics. The total number of vacancies in the sintered body and the number of vacancies in the grains can be calculated, for example, by cutting the sintered body, polishing the cut surface with mirror surface, and performing SIM (Scann).
ing Ion Microscopy) image. The SIM image is an SEM (Sca
nningElectron Microscopy)
Unlike an image or an optical microscope image, contrast is obtained depending on the crystal orientation of each crystal grain, so that grain boundaries and intra-grain vacancies can be recognized without etching. In addition, by observing grain boundaries and intra-grain vacancies by etching the mirror-polished surface, SEM (Scanning Electron)
It is also possible to count all vacancies / intra-granular vacancies by using n Microscopy) or an optical microscope.

It is considered that the voids in the crystal grains are formed by being left in the grains without being discharged to the grain boundaries because of the rapid progress of sintering. Therefore, the number of holes in the grains can be reduced by slowing the progress of sintering. As a result of studying a method for achieving such an object, the present inventors reduced the void ratio in the crystal grains by setting the sintering temperature and the atmosphere at the time of sintering within a predetermined range, and
It was found that the D characteristic was improved. That is, when the atmosphere during sintering is set to an oxygen partial pressure of 5% to the atmosphere and the sintering temperature is set to 1300 to 1380 ° C., the crystal grain size becomes finer and the intragranular vacancies decrease, which is favorable. T
HD characteristics can be obtained. The reason for limiting the sintering temperature to the above range is that if the sintering temperature exceeds 1380 ° C., the ratio of intragranular vacancies increases and the THD characteristics deteriorate, and if it is lower than 1300 ° C., the sintered body density and initial permeability are reduced. This is because the decrease in magnetic susceptibility increases.
Also, the atmosphere during sintering is limited to the above range, because when the oxygen partial pressure is less than 5%, the initial magnetic permeability is lowered and the THD property is deteriorated due to the increase of the intragranular void ratio, and the atmosphere is more This is also because when the oxygen partial pressure is high, the cost for introducing oxygen gas increases and it is not practical.

The present inventors have further studied the method of obtaining a good THD characteristic by reducing the ratio of vacancies in the crystal grains, and as a result, it is particularly effective to keep the temperature rising rate within a certain range. It was one that was found. That is, the temperature rising rate from 1000 ° C. to the sintering temperature is 5 ° C./hour
By setting the temperature to 150 ° C./hour, intragranular vacancies are reduced and good THD characteristics can be obtained. Decreasing the heating rate is
When the high magnetic permeability material is manufactured by increasing the grain size, the decrease in the temperature rising rate is not always preferable, because the crystal grains become finer. However, as a result of the crystal grain size becoming finer and the intragranular vacancies decreasing by setting the heating rate within a predetermined range, the THD characteristics are improved and the initial permeability is increased on the contrary, which is good. It is possible to obtain a Mn-Zn based ferrite sintered body having both excellent THD characteristics and high magnetic permeability. The reason for limiting the rate of temperature rise to the above range is that
This is because when the heating rate exceeds 150 ° C./hour, the ratio of the number of intragranular vacancies to the total number of vacancies increases and good THD characteristics cannot be obtained, and the heating rate is less than 5 ° C./hour. This is because the sintering process requires a great deal of time, which significantly deteriorates the productivity. In order to reduce the number of intragranular vacancies and obtain better THD characteristics, it is more preferably 5 ° C. /
Time to 100 ° C./hour.

The temperature rising rate from room temperature to 1000 ° C. is selected in accordance with the binder and the like in order to remove the binder used for granulation. Also, 10
From the viewpoint of reducing the proportion of intragranular vacancies, the atmosphere in the temperature raising step from 00 ° C. to the sintering temperature is preferably 1% to atmospheric oxygen partial pressure, and more preferably 5% to atmospheric air. In the middle.

Further, in the present invention, CaO is used as an accessory component.
0 to 0.2 wt% (excluding 0) of Ca and SiO
By including 0 to 0.01 wt% (including 0) of Si in terms of ₂ , the number of intragranular vacancies can be reduced and good THD characteristics can be obtained. Ca forms a grain boundary layer with Si,
It is known that the resistivity is increased and the eddy current loss is reduced. However, the inclusion of Ca contributes to the improvement of THD characteristics by making the crystal grains fine and reducing the number of intragranular vacancies. C
The reason for limiting the a content to the above range is that the Ca content contributes to the refinement of the crystal grains and the reduction of the number of vacancies in the grain as described above. This is because growth occurs and, conversely, the THD characteristic deteriorates. Also, S
This is because i forms a grain boundary layer together with Ca, but if it exceeds 0 to 0.01 wt% (including 0) in terms of SiO ₂ , abnormal grain growth also occurs and THD characteristics deteriorate.

The main component composition of the Mn-Zn ferrite in the present invention is 52.0 to 54.0 mol% in terms of Fe ₂ O ₃ , more preferably 52.0 to 53.0 mol%, ZnO.
Converted to 18.0 to 25.0 mol%, more preferably 2
2.0 to 25.0 mol% and the balance manganese oxide. The reason why the main component is limited to this range is as follows. By changing the ratio of the main components Fe ₂ O ₃ , ZnO and manganese oxide, the Curie temperature (Tc) and the so-called secondary peak temperature (Ts) at which the initial permeability μi exhibits a maximum can be controlled. The temperature change of the THD / μa value, which is an index of waveform distortion in the invention, can be controlled by the above principal component ratio. That is, the temperature change of THD / μa is interlocked with the temperature change of μi and becomes minimum at the secondary peak temperature (Ts) of μi. When THD / μa exceeds the secondary peak temperature, it increases with increasing temperature and then decreases again toward the Curie temperature (Tc). It was confirmed that the greater the temperature difference between Ts and Tc, the greater the increase in THD / μa between Ts and Tc. Therefore 0 ℃ ~ 8
In order to obtain stable THD / μa in the range of 5 ° C., it is necessary to control Ts and Tc within a certain range. To achieve such an object, preferably T
s is -20 ° C to 50 ° C and Tc is 90 to 160 ° C, more preferably Ts is -20 ° C to 50 ° C and Tc is 90 to 160 ° C.
140 ° C, and even more preferably Ts is 0 ° C to 40 ° C and Tc is 100 ° C to 130 ° C.

When Fe ₂ O ₃ is less than 52.0 mol%, Ts shifts to the high temperature side, and as a result, the increase of THD / μa becomes remarkable at low temperature, and when it exceeds 54.0 mol%, Ts shifts to the low temperature side. Result of shift THD / μ between Ts and Tc
This is because the increase of a becomes large. More preferably 5
By setting it as 2.0 to 53.0 mol%, a smaller THD / μa value can be obtained in the normal temperature range of 0 ° C. to 85 ° C.

Further, ZnO is limited to the above range because
If ZnO is less than 18.0 mol%, Tc shifts to the high temperature side, and as a result, the increase in THD / μa between Ts and Tc becomes large, while if it exceeds 25.0 mol%, THD / μa increases.
This is because c shifts to the low temperature side and becomes equal to or lower than the upper limit of the practical temperature, and it cannot be practically used.

In the present invention, the above main component and by-product are formed.
It does not deny the inclusion of components other than the above, but may
In addition, it may contain components other than the above main components and subcomponents.
It For example, from the viewpoint of promoting sintering, Bi_TwoO_ThreeIn conversion
0 to 0.015 wt% (including 0) Bi, Nb_TwoO₅
0 to 0.03 wt% (including 0) Nb and MoO
_Three0 to 0.01 wt% (including 0) of Mo and Zr
O_Two0 to 0.03 wt% Zr (including 0), V
_TwoO₅0, 0.05 wt% (including 0) V and T
iO_Two0 to 1.0 wt% (including 0) of Ti and S
nO_Two0 to 0.5 wt% (including 0) of Sn
One kind or two or more kinds can be contained.

[0023]

EXAMPLES The Mn—Zn based ferrite sintered body according to the present invention will be specifically described below. Fe ₂ O ₃ 5
2.50 mol%, 23.10 mol% ZnO, and the balance manganese oxide (using Mn ₃ O ₄ ) were weighed and mixed, and calcined at 850 ° C. for 2 hours. In this, 0.005 wt% in terms of CaO (note that CaCO ₃ was used in the present invention), S
It was added so as to be 0.002 wt% in terms of iO ₂ .
Next, after pulverizing with a wet ball mill for 5 hours, a binder was added to these, the mixture was granulated with a spray dryer, compression-molded into a ring shape, and then subjected to the sintering described below. That is, in the atmosphere and the sintering temperature shown in Table 1, the temperature rising rate from 1000 ° C. was set to 150 ° C./hour, and after sintering for 5 hours, it was cooled in a nitrogen atmosphere in which the oxygen concentration was controlled. The initial magnetic permeability and THD / μa at 25 ° C. of the obtained ring-shaped sintered body having an outer diameter of 25 mm, an inner diameter of 15 mm and a height of 5 mm were measured. The number of windings in the ring shape has an inductance of 3 mH
It was adjusted so that The THD is measured by an audio analyzer (Sys) manufactured by Audio Precision Co., Ltd. shown in FIG.
temTwo) was used, the measurement frequency was 5 kHz, and the measurement magnetic flux density was 30 mT. In addition, the cross section of the ring-shaped sintered body was mirror-polished and a SIM image of 700 times was used.
The total number of vacancies (N _a ) and the number of intragranular vacancies (N _i ) in the region of m × 120 μm were counted, and the ratio of intragranular vacancies was calculated by the following formula. Ratio of voids in grains = 100 × (N _i / N _a ) [%]

Table 1 shows the evaluation results of the ring-shaped samples. In the table, those within the range of the present invention were taken as Examples and those outside the range were taken as Comparative Examples. As shown in Table 1, by setting the ratio of intragranular vacancies to the number of vacancies within the range of the present invention, TH
It can be seen that an Mn-Zn based ferrite sintered body having a small D / [mu] a and a high initial permeability can be obtained. Further, by setting the sintering atmosphere and the sintering temperature within the ranges of the present invention, a Mn—Zn-based ferrite sintered body having a small ratio of intragranular vacancies to all vacancies and a small THD / μa is manufactured. Know that you can

[0025]

[Table 1]

52.50 mol% of Fe ₂ O ₃ , 23.10 mol% of ZnO and the balance manganese oxide (using Mn ₃ O ₄ ) were weighed and mixed, and calcined at 850 ° C. for 2 hours. In addition to this, 0.005 wt% in terms of CaO (note that CaCO ₃ was used in the present invention) and 0.00 in terms of SiO ₂
It was added so as to be 2 wt%. Next, after crushing with a wet ball mill for 5 hours, a binder is added to these,
After granulation with a spray dryer, compression molding into a ring shape was performed and then sintering was performed with the following contents. That is, in the atmosphere,
After raising the temperature range of 1000 ° C. to 1360 ° C. at a predetermined heating rate shown in Table 2 and sintering at 1360 ° C. for 5 hours,
It was cooled in a nitrogen atmosphere with controlled oxygen concentration. The initial magnetic permeability and THD / μa at 25 ° C. of the obtained ring-shaped sintered body having an outer diameter of 25 mm, an inner diameter of 15 mm and a height of 5 mm were measured. The number of windings, THD measurement conditions, etc. were the same as those in the above-described embodiment.

Table 2 shows the evaluation results of the ring-shaped sample. In the table, those within the range of the present invention were taken as Examples and those outside the range were taken as Comparative Examples. As shown in Table 2, by setting the ratio of intragranular vacancies to the total number of vacancies within the range of the present invention, T
It can be seen that a Mn-Zn ferrite having a small HD / μa and a high initial permeability can be obtained. In addition, S of Example 7
The IM image is shown in FIG. 1 and the SIM image of Comparative Example 5 is shown in FIG.
It can be seen that the ratio of intragranular vacancies is remarkably reduced by setting the heating rate within the range of the present invention. Ie 1000
By setting the rate of temperature increase from ℃ to the sintering temperature within the range of the present invention, the ratio of intragranular vacancies to the total number of vacancies is small, and THD /
It becomes possible to manufacture a Mn—Zn-based ferrite sintered body having a small μa and a high initial permeability.

[0028]

[Table 2]

Next, in the composition ratio shown in Table 3, Fe_TwoO_Three, Z
nO, manganese oxide (Mn_ThreeO_FourWeigh) and mix
Then, it was calcined at 850 ° C. for 2 hours. In addition to this, CaO (Ca
CO _ThreeUsed), SiO_TwoContent in the ferrite core
However, CaO (in the present invention, CaCO_ThreeConversion)
0.005wt%, SiO_Two0.002 wt% in conversion
And pulverize with a wet ball mill for 5 hours.
It was Add a binder to these and spray dryer
After granulating with, press-molding into ring shape,
I gave it to the conclusion. That is, in the atmosphere, 1000 ° C to 1
Raises temperature range of 360 ℃ at a heating rate of 100 ℃ / hour
And then control the oxygen concentration after sintering at 1360 ° C for 5 hours
And cooled in a nitrogen atmosphere. The obtained outer shape is 25 mm,
For a ring-shaped sintered body with an inner diameter of 15 mm and a height of 5 mm at 25 ° C
Initial permeability and temperature dependence of initial permeability and THD / μa
Existence was measured. The number of windings and THD measurement conditions are as described above.
The conditions were the same as in the example.

The evaluation results of the ring-shaped sample are shown in Table 3 and
It shows in Table 4. In the table, those within the scope of the present invention are shown as examples.
However, those outside the range were used as comparative examples. Table 3 shows 0 ° C to 85 ° C
Of the initial permeability μi and THD / μa in the temperature range up to
The minimum and maximum values are shown along with the measured temperature, but examples
Is applicable in the temperature range from 0 ℃ to 85 ℃.
THD / μa is -135 dB or less (THD /_FAt -114
dB or less), and Fe _TwoO_Three, ZnO, manganese oxide
Is within the range of the present invention.
Mn-Zn-based blower with good THD / μa in a certain temperature range
An ito sintered body can be obtained.

[0031]

[Table 3]

[0032]

[Table 4]

Next, 52.40 mol% of Fe ₂ O ₃ and Z
25.00 mol% of nO and the balance manganese oxide (Mn ₃ O
₄ ) was weighed and mixed, and calcined at 850 ° C. for 2 hours. CaO (using CaCO ₃ ), SiO ₂
Was added so that the content in the ferrite core would be the composition shown in Table 5. In Table 5, there are Examples and Comparative Examples in which the composition amount of SiO ₂ is parenthesized, but this is mixed in the main component as an impurity and contained in the ferrite sintered body.
The amount of iO ₂ is shown, which is added to the raw material to be distinguished from the amount of SiO ₂ contained in the ferrite sintered body. In addition, in general, ferrite sintered body as impurities,
Metal elements such as V, Co, Ni and Zr may be contained. Next, after crushing with a wet ball mill for 5 hours,
A binder was added to these, and the mixture was granulated with a spray dryer, compression-molded into a ring shape, and then subjected to sintering with the following contents. That is, in the atmosphere, 1000 ° C to 1360
The temperature range of ℃ is raised at a heating rate of 150 ℃ / hour, 1
After sintering at 360 ° C. for 5 hours, it was sintered in a nitrogen atmosphere with controlled oxygen concentration. Obtained outer diameter 25 mm, inner diameter 1
The ring-shaped sintered body having a size of 5 mm and a height of 5 mm was measured for the initial magnetic permeability at 20 ° C. and the temperature dependence of the initial magnetic permeability and THD / μa. The number of windings, THD measurement conditions, etc. were the same as those in the above-described embodiment.

Table 5 shows the evaluation results of the ring-shaped samples. In the table, those within the range of the present invention were taken as Examples and those outside the range were taken as Comparative Examples. Although not specified in the table, in the sintered body structures of the samples of Comparative Example 10 containing 0.3 wt% CaO and Comparative Example 11 containing 0.015 wt% SiO ₂ , both were Abnormal grain growth was confirmed. As shown in Table 5, by setting CaO and SiO ₂ in the range of the present invention, Mn-Zn having a small THD / μa.
It can be seen that a system ferrite can be obtained.

[0035]

[Table 5]

[0036]

According to the present invention, by setting the ratio of intragranular vacancies to the total number of vacancies within a predetermined range, the output waveform distortion with respect to the input wave is small, and the Mn-Zn system ferrite having excellent THD characteristics is obtained. A sintered body and a manufacturing method thereof can be provided.

[Brief description of drawings]

FIG. 1 is a micrograph of a sintered body according to an example of the present invention.

FIG. 2 is a micrograph of a conventional sintered body.

FIG. 3 is a measurement circuit diagram for THD characteristic evaluation.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G018 AA08 AA21 AA25 AA31 AC14                       AC16                 5E041 AB02 AB19 BD01 CA01 HB03                       HB11 NN06 NN18

Claims (5)

[Claims] 1. A Mn—Zn-based ferrite sintered body containing Fe ₂ O ₃ , ZnO and manganese oxide as main components, wherein the crystal is formed with respect to the total number of holes in the Mn—Zn-based ferrite sintered body. A Mn-Zn ferrite sintered body having excellent THD characteristics, characterized in that the number of voids in the grains is 40% or less. 2. A Fe ₂ O ₃ conversion of 52.0 to 54.0 mol%, a ZnO conversion of 18.0 to 25.0 mol%, a balance of manganese oxide as a main component, and a CaO conversion of 0 as a minor component.
Excellent in THD characteristics according to claim 1, characterized in that it contains Ca of 0.2 wt% (not including 0) and Si of 0 to 0.01 wt% (including 0) in terms of SiO _2. M
n-Zn ferrite sintered body. 3. THD / μa represented by the ratio of the THD value and the amplitude permeability μa has a maximum magnetic flux density of 30 mT and a frequency of 5
-135 dB in the temperature range of 0 ° C to 85 ° C at kHz
The Mn-Zn based ferrite sintered body having excellent THD characteristics according to claim 1 or 2, wherein: 4. A method for producing a Mn—Zn-based ferrite sintered body containing Fe ₂ O ₃ , ZnO and manganese oxide as main components, wherein the sintering atmosphere is oxygen partial pressure of 5% to the atmosphere and the sintering is performed. Mn-Zn excellent in THD characteristics, characterized in that the temperature is set to 1300 ° C to 1380 ° C and the number of intragranular vacancies in the Mn-Zn ferrite sintered body is set to 40% or less of the total number of vacancies.
Of manufacturing a ferrite ferrite sintered body. 5. The Mn-Zn-based ferrite firing excellent in THD characteristics according to claim 4, wherein the temperature rising rate from 1000 ° C. to the sintering temperature is 5 ° C./hour to 150 ° C./hour. A method for producing a bound body.