JP2000327333A - Oxide magnetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an oxide magnetic material comprising an Mn-Zn-based ferrite having a high magnetic permeability and a high impedance. SOLUTION: This oxide magnetic material comprises 0.005-0.025 wt.% of SiO2, 0.02-0.07 wt.% of CaO, 0.005-0.030 wt.% of Bi2O3 and 0-0.060 wt.% (with the proviso that 0 is not included) of K2O as accessory components in an Mn-Zn- based ferrite consisting essentially of 52.0-54.0 mol% of Fe2O3, 19.0-22.0 mol% of ZnO and the balance of MnO and has >=5 μm average crystal grain diameter of a sintered compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide magnetic material, and more particularly to an oxide magnetic material having high magnetic permeability and high impedance in spinel type Mn-Zn ferrite.

[0002]

2. Description of the Related Art In recent years, there have been remarkable technological innovations in miniaturization and high performance of electronic equipment, and accordingly, there has been a demand for higher performance, for example, higher permeability and lower loss of Mn-Ζn ferrite used. Have been. In particular, ferrite cores for noise filters are strongly required to have high permeability and high impedance performance.

[0003] In general, the composition range of the main component of Mn-Ζn-based ferrite having high magnetic permeability is 52.0 to 54.5 m.
ol% Fe ₂ O ₃ , 24.0 to 28.0 mol% Mn
O, and the balance is about ΖnO, and those currently on the market are also in this range. In some cases, the Mn-Δn-based ferrite contains SiO ₂ , CaO, Bi ₂ O _{3, and the} like as accessory components. SiO ₂ and CaO are added for the purpose of forming a high-resistance grain boundary layer, thereby reducing eddy current loss and improving the frequency characteristics of the initial magnetic permeability (μi). Bi ₂ O ₃ is added for the purpose of promoting grain growth, and is for obtaining a large crystal grain size necessary for obtaining a high initial magnetic permeability. On the other hand, when the initial permeability maintains a high value up to a high frequency, the imaginary part (μ ′)
The peak value of ') appears on the high frequency side, and the impedance (Ζ) also increases.

In order to achieve a high initial magnetic permeability, it is necessary not only to examine the above composition to select an optimum composition, but also to make the crystal grain size relatively large and uniform. .

[0005]

Although Bi ₂ O ₃ is effective in promoting grain growth, it is also a factor that promotes abnormal grain generation. The abnormal grains increase the eddy current loss, reduce the specific resistance, and also cause a significant decrease in impedance. For this reason, it has been difficult to simultaneously achieve high initial permeability and high impedance characteristics.

An object of the present invention is to provide an oxide magnetic material composed of Mn-Δn-based ferrite having high magnetic permeability and high impedance.

[0007]

The inventor of the present invention has achieved the above object.
As a result of various studies to achieve this, the main component composition was 5%.
2.0 to 54.0 mol% Fe_TwoO_Three, 19.0-2
2.0 mol% of {nO, Mn-} composed of balance MnO
n-type ferrite contains 0.005 to 0.02 as an auxiliary component
5wt% SiO_Two, 0.02-0.07 wt% Ca
O, 0.005 to 0.030 wt% Bi_TwoO_Three, 0
0.060 wt% (but not including 0) K _TwoContains O
Higher initial permeability and high impedance characteristics
Was obtained. In addition to the above composition,
By setting the average crystal grain size of the sintered body to 5 μm or more,
High permeability oxidation with initial permeability and high impedance characteristics
It has been found that a magnetic material can be reliably obtained.

The oxide magnetic material comprising the Mn-Δn-based ferrite of the present invention has a higher initial permeability, higher specific resistance and higher impedance than conventional Mn-Δn-based ferrite. This is because, by having a high specific resistance, the frequency characteristic of the initial magnetic permeability is improved, whereby the peak value of the imaginary part of the initial magnetic permeability is shifted to a high frequency side, and a high impedance is obtained. It is understood that a high initial magnetic permeability was obtained by setting the average crystal grain size of the sintered body to 5 μm or more.

Although Bi ₂ O ₃ was added, the grain growth was promoted as described above, but the addition of K ₂ O made it possible to suppress the occurrence of abnormal grains.

The main component composition is 52.0-54.0 mol%
Of Fe ₂ O _3, 19.0~22.0mol% of ZetanO, to that the remainder MnO, first, the Fe ₂ O _3, 52.0mo
If the amount is less than 1%, the impedance is lowered. On the other hand, if it exceeds 54.0 mol%, a sufficient initial magnetic permeability cannot be obtained. Next, ΖnO is 19.0 m
ol%, sufficient initial magnetic permeability cannot be obtained.
If it exceeds 22.0 mol%, the Curie temperature (hereinafter, Tc
This is because it is not practical.

The sub-components are 0.005 to 0.025 wt% SiO ₂ , 0.02 to 0.07 wt% CaO, 0.0
05～0.030Wt% of Bi ₂ O _3, 0~0.060w
First, the K ₂ O of t% (however, excluding 0) was set as follows.
SiO ₂ is less than 0.005 wt% and CaO is 0.1 wt%.
If the content is less than 02 wt%, a high-resistance grain boundary layer cannot be obtained, and high impedance cannot be obtained. On the other hand, Si
O ₂ exceeds 0.025 wt%, and CaO is 0.2%.
If it exceeds 07 wt%, a sufficient initial magnetic permeability cannot be obtained. Next, if Bi ₂ O ₃ is less than 0.005 wt%, the effect of crystal grain growth cannot be obtained, while if it exceeds 0.030 wt%, abnormalities will occur even if K ₂ O within the above range is added. This is because grain growth cannot be suppressed, and therefore, eddy current loss increases due to generation of abnormal grains, and specific resistance and further impedance are reduced. Also, K ₂ O is 0.060
If the content exceeds wt%, solid solution is formed as an impurity in the crystal grains, and the initial magnetic permeability is reduced. The reason why the average crystal grain size of the sintered body is set to 5 μm or more is that if the average crystal grain size is less than 5 μm, a sufficient initial magnetic permeability cannot be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an oxide magnetic material and a method for manufacturing the same according to an embodiment of the present invention will be described. (Example 1) In Example 1, the composition ranges of Fe ₂ O ₃ , ΔnO, and MnO constituting the above-described main components were changed, and the sub-components were constant. Characteristics such as Curie temperature, initial magnetic permeability, and impedance were examined. In this example, the average crystal grain size of the sintered body was different between the invention product and the comparative product.

That is, first, as Invention Products 1 to 3, ΔnO in the main component composition was fixed at 20.5 mol%, and Fe ₂ O ₃ was 52.0, 53.0, and 54.0 mol, respectively.
% And the balance of MnO, and the sub-components are constant for the inventions 1 to 3, and 0.055 wt% of Ca (OH) ₂ , 0.020 w in terms of 0.015 wt% of SiO ₂ and CaO.
0.030 wt% K ₂ in terms of t% Bi ₂ O ₃ and K ₂ O
CO ₃ was weighed and mixed for 2 hours using an attritor. After mixing, the mixture was granulated with a spray dryer. afterwards,
Each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground by an attritor. After crushing, granulate with a spray drier, 25mmφ-15mmφ-
It was pressed into a 12 mm toroidal shape and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

Further, as Comparative Products 1 and 2, ΔnO of the main component composition was kept constant at 20.5 mol% similarly to Invention Products 1 to 3, and Fe ₂ O ₃ was 51.0 mol and 55.0 mol, respectively.
1%, the balance being MnO, and the minor component was Comparative Product 1,
In the same manner as in Invention products 1 to 3, 0.015 wt% Si
Mn-Δn-based ferrites containing O ₂ , 0.055 wt% CaO, 0.020 wt% Bi ₂ O ₃ , and 0.030 wt% K ₂ O, respectively, were produced in the same process.
In addition, in Invention products 1 to 3, the average crystal grain size of the sintered body was 5.0.
μm, that of Comparative Product 1 was 5.5 μm, and that of Comparative Product 2 was 4.5 μm.

Next, as invention products 4 to 7, the main component composition
Of which Fe_TwoO_ThreeIs fixed at 52.5 mol%, and
{NO is 19.0, 20.0, 21.0, 22.0mo
1%, the balance being MnO, and the subcomponents are invention products 1 to 3
A sample similar to the above was produced in a similar step. In addition, comparison product
3 and 4, Fe in the main component composition_TwoO_ThreeThe invention 4 ~
7 and the same at 52.5 mol%.
When O is 18.0, 23.0 mol%, and the balance is MnO,
In both cases, the sub-component is 0.015 w as in the case of invention products 4 to 7.
t% SiO_Two, 0.055 wt% CaO, 0.02
0wt% Bi_TwoO _Three, 0.030 wt% K_TwoO,
Each containing Mn-Ζn-based ferrite is processed in the same process.
Produced. In the inventions 4 to 7, the average crystal grain of the sintered body was used.
The diameter is 5.0 μm, and that of Comparative product 3 is 4.5 μm.
In the case of the product 4, the thickness was 5.5 μm.

Table 1 shows the average crystal grain size, the specific resistance, the Curie temperature, the initial permeability (μi) at 100 kHz, and the impedance of 10 turns when the number of turns is 10 for the invention products 1 to 7 and the comparison products 1 to 4. The maximum value (Ζmax) is shown.

[0017]

[Table 1] From Table 1, first, from invention products 1 to 3 and comparison products 1 and 2,
In the main component composition, ΔnO was constant at 20.5 mol%, and F
By increasing e ₂ O _{3 in} the range of 51.0 to 55.0 mol%, and thus decreasing (remainder) MnO in the range of 28.5 to 24.5 mol%, the specific resistance becomes 35 to 100 Ω-c.
m, and the Curie temperature also increases to 130 to 160 ° C. The initial permeability (μi) at 100 kHz and the maximum value of the impedance (Ζm
ax), it was found that μi decreased from 10,000 to 4000, while Δmax increased from 2500 to 5600Ω.

In Table 1, in Comparative Example 1 in which 51.0 mol% of Fe ₂ O ₃ was used, the specific resistance was as low as 35 Ω-cm.
Is as high as 10000, but Δmax is too low at 2500Ω, and Comparative Example _{2 having} 55.0 mol% of Fe ₂ O ₃ has a high specific resistance of 100Ω-cm and a Δmax of 560.
Although it is as high as 0Ω, μi is as low as 4000.

On the other hand, 52.0 to 54.0 mol% of Fe
Inventive products 1 to ₃ having ₂ O ₃ had a specific resistance of 50,
70, 80 Ω-cm, μi is 8000, 6500, 50
00 and Δmax became 3300, 4000 and 4800Ω.

Further, even if Fe ₂ O _{3 is set} to 52.5 mol% in the same range as the invention products 1 to 3, 18.0 mol% of Δ
In Comparative Product 3 in which nO was used, the specific resistance was as high as 100 Ω-cm and Δmax was as high as 5700 Ω, but μi was too low as 3800. Has a specific resistance of 35Ω-
cm, and Δmax is too low, 2800Ω. In Comparative Product 4 containing 23.0 mol% of ΔnO, the Curie temperature is lowered to 135 ° C., which is not practical.

On the other hand, the content of Fe ₂ O ₃ was set to 52.5 mol% in the same range as the invention products 1 to 3, and 19.0 to 22.0 mol
% Of ΔnO, the specific resistance is 90, 80, 70, 55 Ω-cm, and μi is 5000, 5
500, 6500, 8000, Ζmax is 5000, 4
500, 4000, and 3500 Ω.

As described above, the main component composition is 52.0-54.
The inventions 1 to 7 comprising 0 mol% of Fe ₂ O ₃ , 19.0 to 22.0 mol% of ΔnO, and the balance of MnO have high specific resistance, relatively high initial magnetic permeability (μi) and high impedance (Δmax). ) At the same time. In addition, the Curie temperature was found to be 140 ° C. or higher, and a practically high height was obtained. (Example 2) In Example 2, the composition of the main component was fixed,
Among the above-mentioned subcomponents, the composition ranges of SiO ₂ and CaO were changed respectively, and Bi ₂ O ₃ and K ₂ O were fixed, and the specific resistance, Curie temperature, initial permeability, impedance, etc. were determined for each oxide magnetic material. I examined the characteristics of

First, as invention products 8 to 10, the main component composition was 52.5 mol% of Fe ₂ O ₃ , 21.0 mol.
% Of ΔnO and the balance of MnO are fixed, and among the subcomponents, S
iO ₂ was adjusted to 0.005, 0.015, and 0.02, respectively.
5 wt%, and other auxiliary components such as CaO and Bi
₂ O ₃ and K ₂ O are fixed and converted to CaO by 0.055
wt% Ca (OH) ₂ , 0.020 wt% Bi
0.030 wt% K ₂ CO ₃ in terms of ₂ O ₃ and K ₂ O was weighed and mixed for 2 hours using an attritor. After mixing
Granulated with a spray dryer. Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground by an attritor. After pulverization, the mixture was granulated by a spray drier, pressed into a toroidal shape of 25 mmφ-15 mmφ-12 mm, and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

In Comparative products 5 and 6, the main component composition was constant as in Invention products 8 to 10.
O ₂ was not added (0.000 wt%),
30% by weight, and other sub-components such as CaO and B
Mn-Δn-based ferrites in which i ₂ O ₃ and K ₂ O were constant at 0.055, 0.020, and 0.030 wt%, respectively, were produced in the same steps as in Inventions 8 to 10.
In addition, the average crystal grain size of the sintered body was 5.0 μm in each of Invention Products 8 to 10 and Comparative Products 5 and 6.

Next, as invention products 11 to 13, the main component composition was fixed, and among the sub components, SiO ₂ was 0.015 watts.
t%, CaO is 0.020, 0.05 respectively
5, 0.070 wt%, and other sub-components, Bi ₂ O _3, are 0.020 wt%, and K ₂ O is 0.030 wt%.
% Were prepared in the same process as the inventions 8 to 10. In addition, invention products 11 to 1 were used as comparative products 7 and 8.
3, the main component composition is constant, and the
O ₂ is constant at 0.015 wt%, and CaO is 0.1% each.
With the 010,0.080wt%, the Bi ₂ O ₃ is another subcomponent 0.020wt%, K ₂ O 0.030
A Mn-Δn-based ferrite having a constant wt% was produced in the same process. In addition, invention products 11 to 13 and comparison products 7 and 8
In both cases, the average crystal grain size of the sintered body was 5.0 μm.

Table 2 shows the average crystal grain size, the specific resistance, the Curie temperature, the initial magnetic permeability (μi) at 100 kHz, and the impedance when the number of windings is 10 turns for the invention products 8 to 13 and the comparison products 5 to 8. The maximum value (Ζmax) is shown.

[0027]

[Table 2]From Table 2, first, invention products 8 to 10 and comparative products 5 and 6
Et al., SiO as a subcomponent _TwoIs not added (0.000wt
%) To 0.030 wt%.
The specific resistance has increased to 40 to 90 Ω-cm. 100k
Initial permeability (μi) at 10 Hz and 10 turns
The maximum value (イ ン ピ ー ダ ン ス max) of the impedance when
Decreases from 9800 to 4200, while Ζma
x is found to increase from 2900 to 5500Ω
did.

In Table 2, the comparative product 5 containing no added SiO ₂ has a low specific resistance of 40 Ω-cm and a μi of 9800
高 い max is too low as 2900Ω, and Si
Comparative product 6 in which O ₂ was 0.030 wt% had a high specific resistance of 90 Ω-cm and a high Δmax of 5500 Ω.
μi is too low at 4200. On the other hand, 0.00
Inventions 8 to 10 of 5 to 0.025 wt% SiO ₂
Then, the specific resistance is 55, 70, 80 Ω-cm, μ, respectively.
i is 8500, 6500, 5300, Ζmax is 350
0, 4000, and 4800 Ω.

Further, SiO ₂ was added in the same amount as that of the invention product 9 by 0.01.
Even at 5 wt%, in Comparative Product 7 in which CaO was 0.010 wt%, the specific resistance was as low as 40 Ω-cm, Δmax was too low as 2900 Ω, and CaO was 0.080 wt%.
In Comparative Example 8, the specific resistance was as high as 80 Ω-cm.
Although max is 4400Ω, μi is reduced to 4900. On the other hand, SiO ₂ was set to 0.0
15% by weight, and 0.020 to 0.070% of CaO
%, The specific resistance is 60, 70, 75 Ω-cm, and μi is 7100, 650, respectively.
0,5800, Ζmax is 3600,4000,430
It became 0Ω.

As described above, the main component composition is 52.5 mol%
Of Fe ₂ O ₃ , 21.0 mol% of ΔnO, and the balance of MnO, and 0.005 to 0.025 wt% of SiO ₂ , 0.02 to 0.07 wt% of CaO, 0.0
The inventions 8 to 13 containing 20 wt% of Bi ₂ O ₃ and 0.030 wt% of K ₂ O have high specific resistance, and simultaneously obtain relatively high initial permeability (μi) and high impedance (Ζmax) at the same time. I found it easy. (Embodiment 3) In Embodiment 3, the compositions of the main component and the subcomponent were fixed, and the specific resistance and initial permeability were determined for two oxide magnetic materials having different sintering temperatures and, consequently, different average crystal grain sizes of the sintered bodies. I examined characteristics such as magnetic susceptibility and impedance.

That is, first, the invention product 14 was composed of 52.5 mol% of Fe ₂ O ₃ , 21.0 mol% of 、 nO and the balance of MnO, and 0.015 w as a sub-component.
0.055Wt% of Ca (OH) ₂ in terms of t% of SiO _2, CaO, and converted to 0.020 wt% of Bi ₂ O _3, K ₂ O were weighed 0.030wt% K ₂ CO ₃ Using an attritor for 2 hours. After mixing, the mixture was granulated with a spray dryer. Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground by an attritor. After crushing, granulate with a spray dryer,
It was pressed into a toroidal shape of 25 mmφ-15 mmφ-12 mm and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours. The average crystal grain size of the sintered body was 9.5 μm. As Comparative Product 9, as in Invention Product 14, as a main component, 52.5 mol% of Fe ₂ O ₃ , 21.0 mol
1% ΔnO and the balance MnO, and 0.0%
15 wt% SiO ₂ , 0.055 wt% CaO,
0.020 wt% Bi ₂ O ₃ , 0.030 wt% K ₂
A sample containing O was manufactured in substantially the same process except that the firing temperature was 1300 ° C. and the average crystal grain size of the sintered body was 4.0 μm.

Table 3 shows the average crystal grain size, specific resistance, and initial magnetic permeability (μm) at 100 kHz of invention product 14 and comparative product 9.
i), and the maximum value of the impedance (Ζmax) when the number of windings is 10 turns, respectively.

[0033]

[Table 3] Table 3 shows that Comparative Product 9 in which the average crystal grain size of the sintered body was 4.0 μm had μi of 4800, whereas Invention Product 14 in which the average crystal grain size of the sintered body was 9.5 μm was , Μi is 6500, indicating that a high initial magnetic permeability can be obtained. (Example 4) In Example 4, the composition of the main component was fixed,
Of the above-mentioned subcomponents, SiO ₂ , CaO and K ₂ O are fixed, and the specific resistance, Curie temperature, initial magnetic permeability, impedance, etc. are determined for each oxide magnetic material whose composition range is changed for Bi ₂ O _3. I examined the characteristics of

First, as invention products 15 to 17, 52.5 mol% of Fe ₂ O ₃ of the main component composition, 21.0 mol% of ΔnO, the balance MnO, and 0.015 wt% of the subcomponents
0.055 wt% of Ca in terms of SiO ₂ and CaO
0.030 wt% of K ₂ C in terms of (OH) ₂ and K ₂ O
O ₃ is fixed, and Bi ₂ O ₃ is 0.005, 0.
020 and 0.030 wt% were weighed and mixed for 2 hours using an attritor. After mixing, the mixture was granulated with a spray dryer. Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours. The obtained powder was ground by an attritor. After crushing, granulate with a spray drier, 25mm
It was pressed into a toroidal shape of φ-15 mmφ-12 mm, and fired at a firing temperature of 1350 ° C. and a holding time of 2 hours.

The comparative products 10 and 11 are the invention products 1
52.5 mol% of F of the main component composition as in 5 to 17
e ₂ O ₃ , 21.0 mol% of ΔnO, balance MnO, and 0.015 wt% of sub-components as SiO ₂ and CaO, converted to 0.055 wt% of Ca (OH) ₂ and K ₂ O. A sample containing 0.030 wt% of K ₂ CO ₃ , and Bi ₂ O ₃ of 0.000 (no addition) and 0.040 wt%, respectively, was manufactured in the same process.

Table 4 shows that the invention products 15 to 17 and the comparison product 10,
11 average crystal grain size, specific resistance, 10 kHz and 1
The initial magnetic permeability (μi) at 00 kHz and the maximum value of the impedance (Ζmax) when the number of turns is 10 are shown.

[0037]

[Table 4] Table 4 based, Bi ₂ O ₃ is 0.000 (no addition) to 0.04
It can be seen that the average crystal grain size gradually increases to 4.0, 5.5, 8.0, 11.0, and 14.0 by increasing in the range of 0 wt%. Bi ₂ O ₃ is 0.005 to 0.0
Invention products 15 to 17 and comparison product 11 in the range of 40 wt%
In this case, the average crystal grain size is large, and the initial permeability (μi) at 10 kHz is large. However, the invention product 15 containing Bi ₂ O _{3 in} the range of 0.005 to 0.030 wt%.
17, the initial permeability (μi) at 100 kHz as well as at 10 kHz was 6000, 6500, 8000.
And while a large value is obtained, the Bi ₂ O ₃ 0.040
In the comparative product 11 containing wt%, the initial magnetic permeability (μi) at 100 kHz is 4900, which is significantly reduced on the high frequency side.

As described above, Bi ₂ O ₃ is added in an amount of 0.005 to 0.0
It was found that by containing 30 wt%, the average crystal grain size became large and the frequency characteristics of the initial magnetic permeability (μi) became extremely good. (Example 5) In Example 5, the composition of the main component was fixed,
Among the above-mentioned subcomponents, SiO ₂ , CaO and Bi ₂ O ₃ were kept constant, and the specific resistance, Curie temperature, initial permeability, impedance, etc. were determined for each oxide magnetic material whose composition range was changed for K ₂ O. I examined the characteristics of

First, as invention products 18 to 20, 52.5 mol% of Fe ₂ O ₃ , 21.0 mol% of ΖnO, balance MnO, and 0.015 wt% of sub-components as main components
0.055 wt% of Ca in terms of SiO ₂ and CaO
(OH) ₂ , 0.035 wt% Bi ₂ O ₃ is fixed,
0.010-0.060wt each converted to K2O
% K ₂ CO ₃ was weighed and mixed for 2 hours using an attritor. After mixing, the mixture was granulated with a spray dryer. Thereafter, each mixed powder was pre-fired in an atmosphere at 850 ° C. for 2 hours.
The obtained powder was ground by an attritor. After grinding,
Granulate with a spray dryer, 25mmφ-15mm
Press into toroidal shape of φ-12mm, 1350 ℃
At a firing temperature of 2 hours.

The comparative products 12 and 13 are the invention products 1
Similarly to 8 to 20, 52.5 mol% of F of the main component composition
e ₂ O ₃ , 21.0 mol% of ΔnO, balance MnO, and 0.055 wt% of Ca (OH) ₂ , 0.035 w in terms of 0.015 wt% of SiO ₂ and CaO of the subcomponents
Bi ₂ O ₃ of t% was constant, respectively 0.000 (no addition) in terms of K ₂ O, the sample containing K ₂ CO ₃ in 0.080Wt%, was manufactured by the same steps.

Table 5 shows that the invention products 18 to 20 and the comparison product 12,
13 shows the average crystal grain size, the specific resistance, the initial permeability (μi) at 100 kHz, and the maximum value of the impedance (と き max) when the number of turns is 10 turns.

[0042]

[Table 5] From Table 5, Bi ₂ O ₃ was fixed at 0.035 wt% and K ₂
By increasing O in the range of 0.000 (no addition) to 0.080 wt%, the average crystal grain size becomes 13.0, 11.
It can be seen that it gradually decreases to 0, 8.0, 7.0, 4.5. Inventive products 18 to 20 in which K ₂ O is in the range of 0.010 to 0.060 wt%, the average crystal grain size falls to 11.0, the specific resistance is high, and both μi and Δmax have high values. Have been. On the other hand, Bi ₂ O ₃
Comparative product 12 in which K ₂ O is 0.000 (no addition) with t%.
Then, μi is slightly lower at 4800, and Δmax is 2900
Ω. In the comparative product 13 in which Bi ₂ O ₃ is 0.035 wt% and K ₂ O is 0.080 wt%, Δm
Although ax can be obtained at 5600Ω, μi is significantly reduced to 3800.

As described above, K ₂ O is adjusted to 0.010 to 0.06.
It has been found that by adding 0 wt%, abnormal grain growth can be suppressed, and high characteristics can be obtained in both initial magnetic permeability and impedance. (Example 6) In Example 6, the composition of the main component was fixed,
Although SiO ₂ and CaO are similarly contained as accessory components,
When i ₂ O ₃ and K ₂ O are not included (conventional example), Bi ₂ O ₃
The oxide magnetic material of the present invention containing a predetermined amount of K ₂ O and K ₂ O was examined for characteristics such as specific resistance, initial magnetic permeability, and impedance.

First, as invention product 21, the main component composition 5
2.5 mol% Fe_TwoO_ThreeΖn of 20.5 mol%
O, the balance MnO, and 0.015 wt%
SiO _Two, CaO converted to 0.05 wt% of Ca (O
H)_Two, 0.020 wt% Bi _TwoO_Three, K_TwoConverted to O
0.030wt% K_TwoCO_ThreeWeigh and use an attritor
And mixed for 2 hours. After mixing, make with a spray dryer
Granulated. Then, each mixed powder was placed in the air at 850 ° C for 2 hours.
Baked for a while. The obtained powder is pulverized with an attritor.
Was. After crushing, granulate with a spray drier, 25mm
Press to toroidal shape of φ-15mmφ-12mm
And fired at a firing temperature of 1350 ° C and a holding time of 2 hours.
Was. The average crystal grain size of the sintered body was 10.0 μm.
Was.

As a conventional product, 52.5 mol% of a main component composition of Fe ₂ O ₃ , 20.
5 mol% of ΔnO, the balance MnO, and
In terms of 0.015 wt% of SiO ₂ and CaO, 0.0
Although containing 5 wt% of _{Ca (OH) 2, Bi 2} O 3 and K ₂
A sample containing no O (no addition) was produced in the same process. The average crystal grain size of the sintered body was 8.0 μm.

Table 6 shows the average crystal grain size, the specific resistance, the initial magnetic permeability (μi) at 100 kHz, and the maximum value of the impedance (Ζmax) when the number of windings is 10 turns, respectively, for the inventive product 21 and the conventional product. Show.

[0047]

[Table 6] According to Table 6, Bi ₂ O ₃ and K ₂ O were not contained at all (no addition).
In the conventional product of the above, even if the average crystal grain size of the sintered body is 8.0 μm
Even at m, only low values were obtained for the specific resistance, μi, and Δmax. In contrast, 0.020 wt% B
Invention 2 containing i ₂ O ₃ and 0.030 wt% K ₂ O
In the case of 1, high values were obtained for both the specific resistance, μi, and Δmax.

[0048]

As is apparent from the above description, according to the present invention, 52.0 to 54.0 mol% of Fe ₂ O ₃ , 1
9.0 to 22.0 mol% of ΖnO, with the balance being Mn—Zn-based ferrite containing MnO as a main component and 0.1% as a subcomponent.
005 to 0.025 wt% SiO ₂ , 0.02 to 0.
07Wt% of CaO, 0.005~0.030wt% of Bi ₂ O _3, 0~0.060wt% (not inclusive of 0)
Because it contains the K ₂ O, it becomes possible to achieve high initial permeability and high impedance characteristic at the same time. In particular,
By setting the average crystal grain size of the sintered body to 5 μm or more, a high initial magnetic permeability and high impedance characteristics can be reliably obtained. Therefore, it is possible to provide an oxide magnetic material composed of Mn-Δn-based ferrite having high magnetic permeability and high impedance.

Claims (2)

[Claims] 1. An amount of 52.0 to 54.0 mol% of Fe
₂ O ₃ , 19.0 to 22.0 mol% ΔnO, balance Mn
0.005 to 0.025 wt% of SiO ₂ , 0.0
2 to 0.07 wt% CaO, 0.005 to 0.030
oxide magnetic material characterized by containing K ₂ O in wt% of Bi ₂ O _3, 0~0.060wt% (not inclusive of 0). 2. The oxide magnetic material according to claim 1, wherein the average crystal grain size of the sintered body is 5 μm or more.