JPS5946082B2 - Garnet magnetic material for microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferrimagnetic garnet magnetic material for microwave elements such as circulators, isolators, Shear radars, and oscillators used in VHF, UHF, and SHF bands.

In general, the characteristics required of a magnetic material for a microwave device are that the ferromagnetic resonance absorption half-width ΔH is small, the required saturation magnetization value is 4πMs, and the temperature coefficient α of 4πMs is small.

Here, it is assumed that the temperature coefficient α is expressed by the following equation. α=
Δ4πMs'ΔT・4πMs 20℃ ・・・・・・・・・・・・(1) Δ4πMs is the difference between the maximum value and minimum value of 4πMs at -20 to 60℃.

ΔT=600-(-200)=80 4πMs2o℃ is the value of 4πMs at 20℃.

Yttrium iron garnet (hereinafter referred to as YIG) has conventionally been used as a microwave magnetic material. Generally, garnet has the chemical formula (As)[B2](Cs)O,2, where A, B and C are 24C, 16a, and
Hail elements occupying 24d lattice points.

Particularly in magnetic garnet, magnetic ions occupy some or all of these lattice points.

Magnetically, the magnetic moments of the ions are coupled in parallel inside each of (A), [B], and (C), and [B] and (C) or (A) and (C) are antiparallel. It is said to be a combination.

Therefore, the temperature change of saturation magnetization is (A), [B], (C)
This is the vector sum of the temperature changes of each saturation magnetization. Therefore, in order to reduce the temperature change of 4πMs, (A)
Either the temperature change in the magnetic moment of each of [B] and (C) is reduced, or the temperature change in the magnetic moment as the vector sum of (A), [B], and (C) is reduced. In YIG, the temperature coefficient α of 4πMs is (A) because it is a nonmagnetic yttrium ion, so the temperature change in total magnetization is [B]
and (C), and its value is 0.2 to 0.
It is large at 3%/℃.

In addition, Ca, V, In-substituted YIG, which is currently reported to have the smallest ferromagnetic resonance absorption half-width △H, has α
reaches as much as 0.4%/°C.

Therefore, when creating microwave devices using these materials, methods such as using magnetic shunt steel or magnetic shunt ferrite, using them within a certain temperature range, or using them in a constant temperature oven are taken. . On the other hand, by replacing the yttrium ions of {A} with gadolinium ions, which are magnetic ions, the magnetic moments of {A} and (C) become antiparallel, and since their temperature dependencies are different, the observed magnetization It comes to have a temperature called the so-called magnetic cancellation point where the value becomes zero. Since the magnetization becomes zero at this magnetic cancellation point and the temperature of the Curly, the temperature change in magnetization becomes small at temperatures between them. However, the composition of these materials is not properly selected and the absolute value of the magnetocrystalline anisotropy constant K1 is large. Alternatively, the actual situation is that the selected elements are not appropriate and it is difficult to increase the density, so that the value of ΔH becomes extremely large. In the materials reported so far, the actual situation is that when α is small, ΔH becomes large, and when ΔH is small, α becomes large.

The present invention has an extremely small temperature coefficient α of 4πMs, which could not be achieved with conventionally known materials, and a ferromagnetic resonance absorption half-width △.
The purpose is to provide a material with a small value of H.

In order to achieve the above object, in the present invention, the composition {GdzY
3-x-,-ZCax+｝[Fe2-,Sn,](F
e3-XGeX)012, and in the above composition, 0.3≦X≦0.6, 0.3≦y≦0.6, 0.
5≦Z≦2.0 and 30≦80X-280y+80Z
It is characterized by having a composition that satisfies the relational expression ≦75.

Example 1 {Gdl. 8YO. 7-XCaO. 5+x} [Fel.
5snO. 5] (Fe3-XGeX)
Gd so that =0, 0.3, 0.4, 0.5, 0.6
2O3, Y2O3, cacO3, Fe2O3, GeO2
, snO2 raw materials were weighed and mixed in a ball mill to form 90
Calcinate at 0 to 1200℃ for 1 to 10 hours, crush again in a ball mill, and after compression molding at 1250 to 1450℃ for 1 to 24 hours.
Baked for an hour.

As a result of X-ray diffraction of the obtained sample, it was confirmed that all the samples had a single garnet phase. Furthermore, we used a magnetic balance to measure the saturation magnetization from liquid N2 degrees to Kyuri temperature.
The temperature Tmax at which 4πMs becomes the maximum and the temperature Tc at which 4πMs becomes the maximum were measured. Further, the value of the ferromagnetic resonance absorption half width ΔH was measured. These results are shown in Table 1. Example 2 {Gd2. OYO. 5.

caO. 5+,}[Fe2-,Sn,](Fe2.5G
eO. 5) At 012, y=0, 0.3, 0.4, 0
．． A sample was prepared in the same manner as in Example 1 so as to have a value of No. 5, and various characteristics were measured. Table 2 shows the measurement results. Example
3 {GdzY2-ZCal. O} [Fel. 5snO. ，
] (Fe2.5GeO.5)012 Z: 0,0
．． 5.] As is clear from the above examples, the Ge4+ substitution amount X plays an important role in determining the value of 4πMs in the present invention.

Further, the Sn4+ substitution amount y plays an important role in determining the value of Tmax, and this is closely linked to the value of α.
When the value of y is less than 0.3, ΔH becomes impractical. Moreover, if it exceeds 0.6, Tc will decrease and α will increase. Further, the Gd3+ substitution amount z plays an important role in determining the value of 4πMs and Tmax, that is, α. Also,
From the example, if the value of Tmax is between -10°C and +35°C, the temperature coefficient α of 4πMs can be 0.1%/°C, which is about half of that of conventional materials. Therefore, Tmax and X, y
Find the relationship between and z. As is clear from Example 1, x
Tmax changes by about +8°C on average per amount 0.1, and y amount 0
．． The average change is about -28℃ per 1, and the average change is about +8℃ per z amount of 0.1 〇 Also, x = 0.5, y = 0.5
, when z=2.0, 1 (1.0, 1.5, 1, 8, 2.
A sample was prepared in the same manner as in Example 1 so that the
Various characteristics were measured.

Table 3 shows the measurement results. Example 4 {Gdl. 8YO. 3CaO. 9} [Fel. 6snO
．． 4] Example 1 in (Fe2.5vO.5)012
Samples were prepared in the same manner as above and various properties were measured.

Claims (1)

[Claims] 1 {Gd_ZY_3_-_X_-_y_-_ZCa_
X_+_y} [Fe_2_-_ySn_y] (Fe_3
_-_XGe_X)O_1_2, and in the above composition, 0.3≦X≦0.6, 0.3≦y≦0.6
, 0.5≦Z≦2.0, 30≦80X-280y+80
A garnet magnetic material for microwave use characterized by having a composition that satisfies the relational expression Z≦75.