JP2893302B2 - Oxide magnetic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a magnetic core material provided in a communication device or the like, and more particularly to an oxide magnetic material as a magnetic core material for a high frequency band.

[0002]

2. Description of the Related Art Conventionally, soft magnetic materials of this type have a higher electric resistance than metal materials and can have a higher frequency characteristic, so that Mn-Zn ferrite, Ni-Zn ferrite, Mn-Mg A spinel type ferrite sintered body such as a system ferrite is used.

[0003]

However, since these soft magnetic materials are usually magnetic core materials adapted to a frequency of about 10 MHz or less, a loss occurs when they are used in a high frequency band of several tens of MHz or more. It becomes extremely large. For this reason, the conventional soft magnetic material cannot be used as a magnetic core material for a high frequency band.
There is a problem that it is difficult to realize high-precision information processing or the like by increasing the frequency in electronic / communication devices.

[0004] The present invention has been made to solve such problems, and the technical problem thereof is to provide an oxide magnetic material that can be manufactured at low cost and that can be applied as a magnetic core material for a high frequency band. It is in.

[0005]

According to the present invention, Ni,
For a spinel-type ferrite sintered body containing Cu, Co, and Fe oxides as main components, a NiO phase of 0 to 60 watts is added.
An oxide magnetic material containing t% (but not including 0) dispersed therein is obtained.

[0006]

The oxide magnetic material of the present invention will be described in detail below with reference to examples. First, the outline of the oxide magnetic material will be described.

According to the present invention, as a result of various studies, Ni,
For a spinel-type ferrite sintered body containing Cu, Co, and Fe oxides as main components, a NiO phase of 0 to 60 watts is added.
By manufacturing an oxide magnetic material in which t% (but not including 0) is dispersed and contained, the magnetic core loss is small (Q, which is the reciprocal of the loss coefficient tan δ, is improved), and the magnetic core can be increased in frequency. It has been found to be a material.

[0008] Evaluation of the frequency characteristic in the oxide magnetic material, symbol μ10MHz, Q _{ma x,} was used fQ _max. Here, μ10 MHz represents the effective magnetic permeability at 10 MHz, and since this value can increase the inductance, it is generally better to set it higher. However, if it is too high, the high-frequency characteristics deteriorate.

Q _max indicates the maximum value of Q,
The higher the value of the magnetic core material, the higher the performance. fQ
_max indicates the frequency when _Qmax indicates the maximum value, and the frequency before and after that frequency is a frequency band in which the material can be effectively operated as a magnetic core material.

Accordingly, the improved materials and more high frequency, Myu10MHz moderately high, fQ _max is high frequency, Q is required to have a correlation to improve.

The reason why the dispersion content of the NiO phase relative to the spinel-type ferrite sintered body is set to 0 to 60 wt% is apparently due to the inclusion of the NiO phase, the Q _max and fQ _max.
This is because the improvement is recognized. Further, the reason why the dispersion content of the NiO phase is set to 60 wt% or less is that at higher values, the frequency increases, but the Q _max becomes almost the same as the state without the NiO phase, and the μ10 MHz becomes 2, This is because the usefulness on inductance is lower than that of the non-magnetic material 1.

Incidentally, in the oxide magnetic material of the present invention, as a method of measuring the amount of precipitation of the NiO phase, it is obtained by estimating from the intensity ratio of the X-ray diffraction lines of the spinel phase and the NiO phase. The X-ray diffraction lines used here are from the spinel phases (311), (222) and (400). On the other hand, the NiO phase is from (111) and (200). As incident X-rays, Cr-Kα rays were used to improve the state of separation of diffraction rays. Here, (311) indicates the highest diffraction intensity in the spinel phase and (200) indicates the highest diffraction intensity in the NiO phase. Therefore, the sum of the diffraction line intensities from these phases is I _NiO for the NiO phase, I _spinel for the spinel phase, and NiO for the spinel phase.
The intensity ratio of X-ray diffraction lines representing the state of phase precipitation was I _NiO /
(I _spinel + I _NiO ).

Hereinafter, the oxide magnetic material of the present invention will be specifically described with reference to several examples.

Example 1 In Example 1, the chemical composition ratio was N
i _0.8 · Cu _0.2 · Fe _(2- α ₎ · Co _0.1 · O ₄ , where α = 0, _0.1 , 0.15, 0.2,
0.25, 0.3, 0.4, 0.5, 0.6, 0.7,
Iron oxide (α-F) such that 0.8, 0.9, 1.0.
e ₂ O ₃ ), nickel oxide (NiO) and cupric oxide (C
uO) and cobalt trioxide (Co ₂ O ₃ ) as raw materials, and these raw materials were wet-mixed in a ball mill for 20 hours. Next, these raw material mixed powders were calcined in air at 800 ° C. for 2 hours, and then wet-pulverized in a ball mill for 3 hours to obtain molding powders. Furthermore, 1 wt% of PVA was added to these pulverized powders.
% Wet-mixed, with an outer diameter of about 8 at a molding pressure of ² ton / cm ^2.
It was compression molded using a mold so as to form a molded body having a diameter of about 1 mm, an inner diameter of about 1 mm, and a height of about 10 mm. Subsequently, these compacts were sintered at 970 ° C. for 4 hours in the atmosphere, gradually heated, and furnace cooled.

Next, the magnetic core properties of these sintered bodies were measured by a penetration method using an analyzer made of YHP and using a coaxial measuring jig. FIG. 1 shows the relationship between the intensity ratio of the X-ray diffraction line [I _{Ni O} / I _spinel + I _NiO (%)] of each sintered body and the magnetic core characteristics. FIG. Permeability μ10 at 10 MHz with respect to the intensity ratio of the X-ray diffraction line of the body
MHz relationships, FIG (b) is a frequency when the Q _max with respect to the intensity ratio of X-ray diffraction line of each sintered body fQ _max (M
(C) shows the relationship between the maximum value Q _{max and} the intensity ratio of the X-ray diffraction line of each sintered body.

Here, I _NiO is the sum of the diffraction intensities of (111) and (200) of NiO by X-ray diffraction using Cr-Kα, and I _spinel is the spinel phase (311) and (2).
22) is the sum of the diffraction intensities of (400). Therefore,
X-ray diffraction line intensity ratio I _NiO / (I _spinel + I _NiO ) is 0
% Is spinel single phase, and 100% is Ni
O single phase. Incidentally, the numerical value of the intensity ratio does not always coincide with the amount of precipitation, but an increase or decrease in the number corresponds to an increase or decrease in the amount of precipitation.

From the measurement results shown in FIGS. 1 (a) to 1 (c), it can be seen that the precipitation of NiO results in a material having a higher frequency and a clearly improved Q value.
FIG. 1 (a) shows the intensity ratio I _NiO / (I
_spinel + I _NiO ) is 50% or less and μ10 MHz is 2 or more. Therefore, it is understood that the X-ray diffraction line is useful when the intensity ratio is in the range of 0 to 50%.

When the crystal structures of these sintered bodies were observed, it was found that the crystals were not significantly localized locally, and the NiO phase was dispersed in the spinel phase. There was found.

Example 2 In Example 2, the chemical composition ratio was N
i _0.8 .Cu _0.8 .Fe ₂ .Co _0.1 .O ₄ forming powder (this powder is a single phase of spinel) was added with an average particle size of about 0.7
μm nickel oxide (NiO) powder
30, 40, 50, 60, 70 (wt%) mixed and X
A sample for line diffraction was formed.

Next, these samples were subjected to X-ray diffraction in the same manner as in Example 1 to obtain an X-ray diffraction pattern of the spinel phase and the NiO phase.
The intensity ratio of X-ray diffraction lines was determined.

Table 1 shows the relationship (measurement results) between the mixing amount (wt%) of the NiO powder in each sample and the intensity ratio (%) of X-ray diffraction lines.

[0022]

[Table 1]

From Table 1, it can be _{seen that} the intensity ratio of the X-ray diffraction line I _NiO /
It can be seen that the range where (I _spinel + I _NiO ) is 50% or less corresponds to the range where the NiO mixing ratio is 60% by weight or less.

Therefore, when the above embodiments are combined, N
A NiO phase of 0-6 is applied to a spinel-type ferrite sintered body containing an oxide of i, Cu, Co, Fe as a main component.
It can be seen that a material containing 0 wt% (not including 0) dispersed therein becomes an oxide magnetic material for a high frequency band showing an improvement in Q.

In the first embodiment described above, the case where the chemical composition ratio is Ni _0.8 · Cu _0.2 · Fe _(2- α ₎ · Co _0.1 · O ₄ and α = 0 to 1.0 is described. However, the present invention is not limited to this. That is, the present invention only needs to contain oxides of Ni, Cu, Co, and Fe as main components. For example, the substitution amount of the oxides of Cu and Co changes in the above-described chemical composition ratio, Other additives may be contained. Also, the case where the pre-firing of the powder and the sintering of the compact were performed in the atmosphere has been described, but the magnetic product in the sintering is spinel-type ferrite and NiO
If a state in which the phases are dispersed can be obtained, the production method may be without pre-firing, or a coprecipitation method, a hydrothermal synthesis method, a spray roasting method, or the like may be applied. Further, it does not matter whether the firing atmosphere is oxidizing or reducing as compared with the atmosphere. Therefore,
The forming method of the formed body in the oxide magnetic material of the present invention is not limited to those disclosed in the examples.

[0026]

As described above, according to the present invention, an oxide magnetic material applicable as a magnetic core material for a high frequency band can be produced at a low cost by incorporating an appropriate amount of a NiO phase in a sintered spinel ferrite. Will be obtained. As a result, for example, electric / electronic / communication equipment provided with a magnetic core (transformer) using the oxide magnetic material of the present invention can perform information processing at a higher frequency with higher precision than ever before.
Therefore, the oxide magnetic material of the present invention is expected to bring great benefits to the electric, electronic and communication industries.

[Brief description of the drawings]

FIG. 1 shows an intensity ratio [I _NiO / I _spinel ] of an X-ray diffraction line of each sintered body in Example 1 according to the oxide magnetic material of the present invention.
+ I _NiO (%)] and the magnetic core characteristics.
(A) is 10M with respect to the intensity ratio of the X-ray diffraction line of each sintered body.
(B) is the relationship of fQ _max (MHz), which is the frequency at the time of Q _max with respect to the intensity ratio of the X-ray diffraction line of each sintered body, and (c) is the relationship of each sintered body. 2 shows the relationship between the maximum value _Qmax of Q and the intensity ratio of X-ray diffraction lines of FIG.

Claims (1)

(57) [Claims] 1. A spinel type ferrite sintered body containing an oxide of Ni, Cu, Co, Fe as a main component,
An oxide magnetic material comprising a NiO phase dispersedly contained in an amount of 0 to 60 wt% (excluding 0).