JPS6151405B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic material for non-reciprocal circuit elements in microwave and millimeter wave bands. In order to configure non-reciprocal circuit elements such as circulators and isolators used in the microwave and millimeter wave bands, a large saturation magnetic flux density (hereinafter referred to as 4π
Ms), the temperature coefficient of 4πMs is small, the magnetic loss is small (ferromagnetic resonance absorption width (hereinafter referred to as ΔH)), the Curie temperature is high, and the dielectric loss (hereinafter referred to as tanδε) is small.
A magnetic material with excellent overall properties that satisfies these conditions at the same time is absolutely necessary. However, these conditions may include mutually contradictory requirements, and the current situation is that it is difficult to obtain a material that satisfies the required overall characteristics. Currently, microwave and millimeter wave bands, especially 8GHz to 80G
Common magnetic materials commonly used for non-phase rotary circuit elements in the quasi-millimeter wave and millimeter wave bands around Hz are yttrium, iron, garnet, nickel, zinc, ferrite, manganese, magnesium, ferrite, etc. . However, yttrium, iron, and garnet have the disadvantages that the 4πMs value is too small, about 1800 Gauss or less, and the Kyurie temperature is too low, about 280° C. or less, for use in microwave and millimeter wave bands. Further, although nickel, zinc, and ferrite can achieve a 4πMs value of approximately 5000 Gauss, they have the drawback of having a low Kyrie temperature of approximately 300°C. Furthermore, manganese-magnesium ferrite has the drawbacks of a small 4πMs value of about 300 Gauss and a low Curie temperature of about 300° C. or less. On the other hand, the 4πMs value is about 3700 Gauss or more, the ΔH value is about 400 Oersted or less, and the Curie temperature is 400℃.
The above is a material that exhibits fairly good properties.
Lithium ferrite represented by the composition formula Li ₀ . ₅ Fe ₂ . ₅ O ₄ is known. However, the 4πMs value of this lithium ferrite is the desired value (at least
(approximately 500 Gauss), and furthermore, the tan δε value is large, making it difficult to use from the viewpoint of overall characteristics. Therefore, the present inventor attempted to achieve the desired characteristics by substituting a part of the composition of this lithium ferrite with other elements, and carried out detailed experiments on various substitution elements and substitution ratios. As a result of theoretical studies, it has been discovered that the composition of the present invention has unprecedented superiority in terms of comprehensive properties. That is, according to the present invention,
It is expressed by the general formula Li ₀ . _5-0 . _5x-0 . _5y Fe ₂ . _5-0 . _5x-0 . _5y Zn _x Mn _y O ₄ , and x and y in the formula are 0.15≦x≦
A magnetic material for a non-reciprocal circuit element for microwave/millimeter wave bands is obtained, which has a composition defined in the range of 0.45, 0.02≦y≦0.18. Below is a part of the composition of lithium ferrite.
Substitution with Zn and Mn, and the amount of Zn substitution and Mn
The reason for limiting the amount of substitution as in the claims will be explained in detail by citing data. First, when a part _of the lithium ferrite represented by _the composition formula Li ₀ . ₅ Fe ₂ . When, Li _{0.5-0.5x - 0.5y Fe 2.5-0.5x - 0.5y ZnxMnyO 4}
It was found that the entire solid solution was formed in a spinel crystal body expressed by the general formula: As the Zn substitution amount x increases, 4
The πMs value initially shows a tendency to increase gradually, and x
It was found that a peak was formed around = 0.28, and beyond that, it gradually decreased again. Unfortunately, however, as x increases, the dielectric loss tan δε tends to increase slightly. On the other hand, as the Mn substitution amount y increases, tanδ
It was found that ε decreases rapidly at first, but the amount of change in decrease gradually becomes smaller until it reaches a nearly constant value around y=0.08 to 0.10. However, at this point, the inventors were not willing to expect much from the Mn substitution on the 4πMs value. This is because the inventor has previously discovered lithium ferrite.
I have tried replacing with Mn only, and the first
This was because it was known that the result as shown in the figure, that is, the 4πMs value, tends to decrease monotonically as y increases, starting from y=0 without Mn substitution. However, this time I decided to reconsider it in more detail. The reason is the Zn substitution effect and
This is because a fairly simple principle was observed between the Mn substitution effect, that is, there was a tendency for both effects to be effective in arithmetic addition rather than synergistically. Therefore, we thought that increasing the 4πMs value could be achieved by Zn substitution, and decreasing the tanδε value might be achieved by Mn substitution. Therefore, in an attempt to determine the point where the effects of both can be utilized most advantageously overall, even though I had previously obtained the results shown in Figure 1, I changed the direction of y extremely small. I tried to find the change in the 4πMs value again. The results generally reconfirmed the trend shown in Figure 1 previously obtained;
In the region of 0≦y≦0.2, the 4πMs value tends to form a peak around 0.08≦y≦0.12, as shown in Figure 2. I found out. Furthermore, in the process of conducting detailed experimental and theoretical studies, we also determined the amount of Mn substitution, that is, y
It has also been found that increasing the material has the effect of increasing the density of the material after sintering. As mentioned above, Zn substitution and Mn substitution, which we started considering individually, do not hold each other back.
Perhaps I should rather call it luck that it brought about an effect in terms of arithmetic addition. However, it is true that both of these effects work in this way. The following table and Figure 3 show a typical example.

【table】

[Table] The results in the above table are obtained by fixing the amount of Zn substitution at the value x = 0.28, which indicates its maximum effect, and setting the amount of Mn substitution y from 0 to 0.20.
It is scaled in steps of 0.02 within the range of . The experiment started with LiCO ₃ ,
The raw materials Fe ₂ O ₃ , ZnO, and MnCO ₃ were weighed, mixed using a steel ball mill with ethyl alcohol as a dispersion medium, and pre-calcined at 800°C for 4 hours.
After pulverizing with a stirrer and mixing a binder, a molded body was prepared, and the main firing was performed in an oxygen-containing atmosphere at the firing temperatures shown in the table. 4πMs and the Curie temperature were measured using a magnetic balance, and ΔH was measured at 9.3GHz using a 1.0mmφ spherical sample. Tan δε was measured using a TE ₁₁₂ cavity resonator method at 9.3 GHz using a disk sample with a diameter of 13.5 mm and a thickness of 0.25 mm. As a result, according to the present invention, 4πMs exceeds 5000 Gauss at its maximum value, and the tanδε value is approximately 4×
10 ^-3 , ΔH has decreased to about 180 oersted at its lowest value, and the Kyrie temperature is as high as 420 to 465°C, making it a magnetic material for non-reciprocal circuit elements in the microwave and millimeter wave bands that could never be realized before. It was confirmed that a product with excellent overall properties could be obtained with good reproducibility. The results in Figure 3 were obtained using the same method used to obtain the results in the table above, by fixing the Mn substitution amount y and varying the Zn substitution amount x, contrary to the case in the table above. be. In order to avoid complication, Figure 3 shows the two values of Mn substitution amount y=0.08 and Mn substitution amount y=0.
However, as y gradually increases from 0, the data approaches the data of y = 0.08, and when y = 0.10 is exceeded, y =
It shows a tendency to move away from the data of 0.08 and approach the data of y=0. That is, if we comprehensively judge the results in the table above and the results in Figure 3, the amount of Zn substitution x and the amount of Mn substitution y
It can be seen that there is naturally a range from which to choose. This selection was made in the scope of the patent search.
The range is 0.15≦x≦0.45, 0.02≦y≦0.18. The magnetic material having the composition of the present invention determined in this way can be produced under the desired conditions, that is,
It has a large 4πMs value, a small temperature coefficient of 4πMs, a small magnetic loss (a small ΔH value), a high Kyrie temperature, and a small tanδε value. Materials are also important in terms of manufacturing technology.
Also, from the point of view of manufacturing cost, it is an excellent magnetic material for non-reciprocal circuit elements in microwave and millimeter wave bands without any notable drawbacks.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing experimental data obtained by the inventor before the completion of the present invention, and shows the amount of substitution y and 4 when a part of lithium and ferrite is replaced with Mn.
This shows the correlation with the πMs value. This data shows no signs of triggering the present invention. FIG. 2 is a diagram showing the experimental data that triggered the present invention. In the experimental data of FIG. 1, there were 4
It was found that there is a peak of πMs value. FIG. 3 is an example of experimental data prepared to explain the effects of the present invention, and shows the correlation between the Zn substitution amount x and the 4πMs value using the Mn substitution amount y as a parameter.

Claims (1)

[Claims] 1 Li ₀ . _5-0 . _5x-0 . _5y Fe ₂ . _5-0 . _5x-0 . _5y ZnxMnyO ₄ Represented by the general formula, and x and y in the formula are 0.15
A magnetic material for a microwave/millimeter wave band non-reciprocal circuit element, characterized by having a composition defined in the range of ≦x≦0.45, 0.02≦y≦0.18.