JPH081843B2 - Microwave / millimeter wave magnetic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a magnetic material composition used in a high frequency region such as a microwave and a millimeter wave.

<Prior Art> Conventionally, Mn-Mg ferrite, Ni-Zn ferrite, YIG ferrite, lithium ferrite and the like have been used as high frequency magnetic material.

These are excellent materials with saturation magnetization (4πMs) values of 500-4000 Gauss.

Of these, lithium ferrite has 37% 4πMs.
It is as large as about 00 gauss and has a Curie point (Tc) of 650 ° C.
It is a material that can be applied to circuit elements such as highly stable isolators and circulators because it has a high temperature near it and has a small rate of temperature change near room temperature of 4πMs.

<Problems to be Solved by the Invention> However, lithium ferrite has a drawback that loss such as dielectric loss (tan δe) of ferromagnetic resonance absorption half width (ΔH) is larger than that of other ferrites for microwaves and millimeter waves. have.

For example, pure lithium ferrite Li _0.5 Fe _2.5 O ₄ is Δ
H and tan δe are large at 500 Oersted and 0.01 or more, respectively, at a frequency of 10 GH ₂ and cannot be used for actual microwave / millimeter wave circuit elements.

The present invention has been made in view of the above problems, in which a portion of Li _0.5 Fe _2.5 O ₄ is replaced with Ti so that 4πMs can be set to an arbitrary value, and B ₂ O ₃ , It is an object of the present invention to provide a magnetic material for microwave / millimeter wave in which ΔH and tan δe are improved by adding and containing any one or more kinds of SiO ₂ .

<Means for Solving the Problems> In order to achieve the above object, the microwave of the present invention
The magnetic composition for millimeter waves is Li _x Fe _y Ti _z O _{0.5 + y + 1.5z} (however,
x + y + z = 1), x, y,
z is 0.15 ≦ x ≦ 0.30, 0.55 ≦ y <0.85, 0 <z ≦
The main component is a composition in the range of 0.30, and B ₂ O ₃ , SiO ₂
Any one or more of 0.02 mol% or more, 1.0 mol%
The feature is that it is added below. .

<Operation> According to the present invention, 4πMs can be arbitrarily set in the range of 600 to 3700 gauss, and therefore, a material having a value of 4πMs most suitable for the frequency to be used can be selected, and Tc is high, so that the material can be used near room temperature. The temperature change rate of 4πMs is small, and
It is possible to obtain a magnetic body having a sufficiently small ΔH and tan δe and good microwave / millimeter wave characteristics.

The above-mentioned objects, features, and advantages of the present invention will be described below by way of embodiments with reference to the drawings.

<Example> First, as a raw material, high purity _{Li 2 CO 3, Fe 2 O} 3, TiO 2, B
₂ O ₃ and SiO ₂ were prepared. These raw materials were weighed so as to obtain the composition shown in Table 1, and wet-mixed in a ball mill for 16 hours using ethyl alcohol as a dispersion medium. After this mixture was dried, it was calcined at 850 ° C. for 2 hours to obtain a calcined product. This calcined product was put into a ball mill together with ethyl alcohol and an organic binder, and wet-milled for 16 hours. After drying this crushed product, granulate through a 50 mesh net,
The obtained powder was molded into a 3 mm × 3 mm × 20 mm prism with a pressure of 2000 kg / cm ² . After this molded product was fired at 1050-1200 ℃ for 2 hours, it was machined to a ball with a diameter of 1.3mm and a diameter of 1.3m.
A cylindrical sample of m and 16 mm in length was obtained.

For the obtained spherical sample, 4πMs and Tc were measured using a vibrating magnetometer, and 10 GHz was measured in the TE106 cavity resonator.
ΔH at was measured.

Further, ε and tan δe at 10 GHz were measured for the cylindrical sample in the TM010 cavity resonator by using the displacement method. The results are shown in Table 1.

In addition, in Table 1, sample numbers 1 to 7, 12, 13, 18 to 25, 30,
31 and 36 to 42 are out of the scope of the present invention, and those marked with * indicate those which are not suitable for practical use because the values of ΔH and tan δe are large.

In addition, sample numbers 1 to 6 and 19 to 24 are comparative examples in which Ti is not added, and by comparing with other samples to which Ti is added,
It can be seen that the value of 4πMs can be set arbitrarily depending on the addition and the addition amount.

Furthermore, the results of the experimental examples shown in Table 1 are shown as Li _x Fe _y Ti _z O
_It is shown in the three-component composition diagram showing the composition ratio of _{0.5 + y + 1.5z} .
The numbers in this figure represent the sample numbers. In this drawing, the region showing the composition ratio within the scope of the invention is
A quadrangle with vertices A, B, C and D, where z = 0
Is not included).

Next, the reason why the composition range of the present invention is limited will be described.

B as in sample numbers 1, 7, 13, 19, 25 and 31
Addition amount of at least one of ₂ O ₃ and SiO ₂ is 0.02 mol% in total
If it is less than 1, the ΔH and tan δe are large, and are not suitable for practical use.

In addition, B ₂ as in sample numbers 6, 12, 18, 24, 30 and 36
If the total amount of one or more of O ₃ and SiO ₂ exceeds 1.0 mol%, tan δe becomes large, which is not preferable.

When x is less than 0.15 as in sample numbers 37 and 38, ΔH and tan δe increase, which is not preferable.

As in sample numbers 39 and 40, when y is less than 0.55, ΔH and tan δe are large, and Tc is low,
Therefore, the temperature change rate of 4πMs becomes large, which is not preferable.

When x exceeds 0.3, as in sample numbers 41 and 42,
ΔH and tan δe increase, which is not preferable.

On the other hand, the magnetic composition of the present invention has sufficiently small ΔH and tan δe, and has a high Tc.
Furthermore, _x represented by the chemical formula of Li _x Fe _y Ti _z O _{0.5 + y + 1.5z} ,
By appropriately changing y and z within the scope of the present invention, it is possible to freely select the value of 4πMs between 600 and 3700 gauss, and thus to obtain the value of 4πMs most suitable for the frequency to be used. Can be done.

[Brief description of drawings]

The drawing is a three-component composition diagram showing the composition ratio of Li _x Fe _y Ti _z O _{0.5 + y + 1.5z in} the microwave / millimeter wave magnetic material composition according to the present invention.

Claims (1)

[Claims] 1. Li _x Fe _y Ti _z O _{0.5 + y + 1.5z} (where x + y + z
= 1), x, y and z are respectively
0.15 ≤ x ≤ 0.30, 0.55 ≤ y <0.85, 0 <z ≤ 0.30 as the main component, and at least one of B ₂ O ₃ and SiO ₂ in total of 0.
A magnetic material composition for microwaves and millimeter waves, which contains 02 mol% or more and 1.0 mol% or less.