JPS6024568B2 - Gd, Ca, Sn substituted yttrium iron garnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ferrimagnetic garnet used in microwave devices such as circulators and isolators for high frequency bands such as VHF, UHF, and SHF bands, particularly Gd, Ca,
This invention relates to Sn-substituted yttrium iron garnet.

The characteristics possessed by the magnetic material for microwave elements are that the ferromagnetic resonance absorption half-value has a narrow △day, and an appropriate saturation magnetization (4 戀Ms).
, and its temperature coefficient is extremely small.

Generally, the magnetic resonance frequency is expressed by the following equation. ■＝ツ｛
[Ny-N2) 4mMS] [H+(NX-NZ)
4mMs]}★Here: H: Strength of external magnetic field Nx: Demagnetizing field coefficient in the x direction Ny: Demagnetizing field coefficient in the y direction Nz: Demagnetizing field coefficient in the z direction (NX 0 Ny + NZ = 1) y: Magnetic rotation ratio Therefore, if the microwave element is a sphere, Nx=Ny=
Since Nz=1, the above value is unrelated to 4mMs, but when the element has a shape other than a sphere, a change in 4mMs appears as a direct change in .

Many of the elements actually used in circulators, isolators, etc. have shapes other than spheres, and they change as a function of the above-mentioned 'M4T Ms'. Therefore, the temperature coefficient Q' of 4T Ms must be set to a value of 0.1%/°C or less in the operating temperature range of -20 to 60°C. However, in conventional yttrium iron garnet, the above temperature coefficient Q is 0.2 to 0.3% in the above temperature range.
/°C. For this reason, there is no choice but to either use the device by housing it in a tank or use a spherical device. In this case, the former method requires a large amount of cost, and the latter method has the disadvantage that not only the shape of the element is limited, but also that it is extremely difficult to manufacture a spherical element. Generally, garnet is {A3} [B2] (C3)○,2
It has the chemical formula:

A, B, and C represent elements occupying the child points 24c, 16a, and 24d, respectively. Particularly in magnetic garnet, magnetic ions occupy part or all of the child points. Therefore, within each sublattice of [B], the magnetic moment is ferromagnetically coupled, and antiferromagnetically coupled with [B], and {
A}'s magnetic ion receives the 'CI's molecular field and combines with Ni in the opposite direction. Therefore, the temperature change in saturation magnetization is {A}
[B] is the sum of temperature changes in saturation magnetization of each sublattice. Therefore, in order to reduce the temperature change in saturation magnetization, it is necessary to either reduce the temperature change of each sublattice to 4.0 or reduce the temperature change as a sum. In the above-mentioned yttrium iron garnet, since the yttrium ions occupying the 24c sublattice are non-magnetic, the temperature change in the total magnetization is the difference between the changes in the 16a and 24d sublattices, and its value is 0. 2-0.
As mentioned above, it is extremely large at 3%/°C. At present, as polycrystals, the smallest Ca, V,
In ln-substituted yttrium iron garnet, -20
The temperature coefficient Q of 4mMs in the range of qo to 6000 reaches as much as 0.4%'°C. However, by replacing the non-magnetic yttrium ion of 24c with a magnetic ion, the magnetic moments of the sublattice become opposite to each other, that is, they cancel each other out, and the value of magnetization observed externally becomes zero. It has a magnetic cancellation point. Since the magnetization is zero at the upper atmosphere magnetic cancellation point and the Curie temperature Tc, the temperature coefficient of saturation magnetization can be set to 4.in the temperature range between them. A.S. Hu ship on etc. is 1. E. E.
E Transaction on Mag. V
oIMog published o. 3196 snake. In 610-613, {Y3-2raCa2xGL}[Fe2-zlnz]
(Fe3-ryVxA1y) ○Although it has been reported that garnet with the same composition has a minimum temperature coefficient of 0.24%/OC, ``In actual use, temperature compensation means are required.'' At the same time, △H during ferromagnetic resonance absorption half value
=7 e, which is extremely large. There are drawbacks. The present invention eliminates the various drawbacks of garnet materials as described above, and
, Ca, Sn-substituted yttrium iron garnet,
By making the composition such that the temperature at which the maximum saturation magnetization occurs between the magnetic cancellation point and the Curie temperature is between -20 and 60 qo, the temperature coefficient of saturation magnetization is extremely small and the temperature coefficient of ferromagnetic resonance absorption is within the half value. The purpose is to provide small garnets.

Example 1 {W2. .

Y,-yCay}[Fe2-yS-](Fe3)0,2
In, y=0. to 0.5 0.6,
Gb203, CaC03, Y203, Fe203, Sn
02 or hydroxides, salt salts, carbonates, etc. that decompose to form the above oxides are weighed to the above composition ratio and mixed in a ball mill. Then, it was heated for 1 to 6 hours at 800 to 1,200°C, then ground again in a ball mill, and after compression molding, 126
It was fired in oxygen for 1 to 8 hours at 0 to 145 pi. The obtained samples were examined by X-ray diffraction, and as a result, it was confirmed that all the samples had a single garnet phase. Next, for the above sample, the saturation magnetization is 4 from -180qo to the Curie temperature.
The temperature change in the middle Ms was determined and the results are shown in FIG.

As is clear from the figure, 4mMs decreases as the temperature rises from -18,000, and reaches a minimum around -16,000. This point is the magnetic cancellation point. When the temperature is further increased, the temperature increases by 4mMs, reaches a maximum value, then decreases, and finally reaches zero. This temperature is the Curie temperature. 4 Ms between the magnetic cancellation point and the Curie temperature
The temperature at which Tmax is the maximum is defined as Tmax. As is clear from FIG. 1, when the proportion y of Sn in [Fe2-ySnO9 is increased, Tmax moves at a rate of -2000C/1 molecular formula. Table 1 shows the results of measuring various characteristics of samples of each of the above compositions.

Table 1 (Gd2.oY, -yCay} [Fe2-ySn
y] Cape e3)○,2 4mMs and Tc in Table 1
The values of each correspond to the values in FIG. 1 above.

In the same table, the temperature coefficient is -4℃ and 19℃ for Tmax.
When oo, it shows 0.09 and 0.05 respectively, but Tm
As ax becomes higher, it follows a tendency to increase again. In Table 1, △H, that is, the value in the half value of ferromagnetic resonance absorption, is calculated by cutting the sample into a disk shape and polishing the surface with N203 to a mirror finish.
Measured at 0 skin Hz. As the value of y increases, △
The value of the day decreases. Example 2 {GdZY2.57C4.5} [Fel. 5S~. 5]
(Fe3).

12, z=1. F1.8, 2.0, 2.2, 2
．． Gd 3, CaC03, Y203, S to be 4
n02 or hydroxide, hakamate, carbonate, etc. which decompose to become the above-mentioned oxides were weighed out to the above-mentioned composition ratio and mixed in a ball mill.

As a result of X-ray diffraction of a sample prepared in the same manner as in Example 1, it was confirmed that all the samples were single-phase garnet. Next, the above sample was prepared in the same manner as in Example 1.
The temperature change in mMs was measured and the results shown in FIG. 2 were obtained.

From the same figure, it can be seen that there are 4 M
It can be seen that the temperature Tmax at which s is maximum moves at a rate of 80 qo/1 molecular formula. Also, 4mMs at room temperature
The value of G is reduced by 35 points per 1 molecule replacement of 10 ions. Table 2 is a table showing the measurement results of the characteristic values of the samples having the above-mentioned respective compositions. Table 2 {GdzY. 5-zCao. 5
}Goe,. 5Sno. 5] (Fe3)012 As is clear from Table 2, the temperature coefficient Q of 4000 ms is -20o to 6
In the range 0oo, it decreases as z increases, and z=2
．． 4 shows 0.06%/°C.

Further, the ferromagnetic resonance absorption half-value at 80 MHz increases as z increases. From the results of the above examples,
Between the magnetic cancellation point and the Curie temperature Tc, y
, even if the values of z are changed, that is, the amount of Sn40 and G is changed, the temperature Tmax at which 4mMs is the maximum is o
If it is between o and 35℃, the temperature coefficient Q'ma0 of 4mMs
．． 0.8%/°C, which is extremely small compared to the conventionally reported value of 0.24%/°C.

Especially when Tmax=20qo, Q=0.05%/q
C. From the results of the above example, the relationship between y, z and Tmax is as follows: {GdzY3-y-zC
ay}[Fe2-ySny] (Fe3) In 0,2, it can be expressed as -84 of Tmax=8th place -20.

Therefore, in order for Tmax to be between 00 and 35°C, O
S8-20W-84S35 In other words, it is sufficient to determine the values of y and z so as to satisfy SII9 of 84S8-20. However, the value of y is a factor that determines the value of the magnetocrystalline anisotropy K, Become.

Therefore, in order to make △day small, it is necessary to set the value of K above to 4. For this purpose, it is desirable that the value of y be large, but if it is too large, the Curie temperature will drop, which is disadvantageous. On the other hand, since it is necessary to take into account the value of Δday, 0.3<y≦0.6 is a desirable value. Also, the value of z is 1.7 based on the relationship between y and z at Tmax.
Must be SzS2.7. However, since the value of Y30 is 31y-z, the minimum is 0 and the maximum is 3, so 0<y10zS3
It is necessary to do so. As described above, the enemy of the present invention, C
a.Sn-substituted yttrium iron garnet is a garnet that eliminates the various drawbacks of conventional garnet materials and has a small temperature coefficient of saturation magnetization and a small half value of magnetic resonance absorption, and is an invention with great industrial effects. .

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams each showing the relationship between temperature and 4mMs in an example of the present invention. Figure 2

Claims (1)

[Claims] 1 {Gd_zY_3_-_y_-_zCa_y} [F
e_2_-_ySn_y](Fe3)O_1_2, 84≦80z-200y≦119, 0.3
It has a composition range of <y≦0.6, 1.7≦z≦2.7, 0<y+z≦3, and the temperature showing the maximum saturation magnetization between the magnetic cancellation point and the Curie temperature is 0 to 35. C. and has a ferromagnetic resonance absorption half width ΔH value of less than 750e.