JPS5842601B2 - Jisei Garnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the composition of magnetic garnet, and more specifically, to a magnetic garnet with a small magnetic resonance width ΔH and a small temperature change in magnetization Ms, which is used in a device utilizing magnetic resonance phenomena. It is something.

The magnetic resonance phenomenon of ferromagnetic materials such as yttrium iron garnet is used in microwave circuit elements and devices such as circulators and filters.

Among the material properties of the ferromagnetic materials used in these elements and devices, the most basic properties are the magnetic resonance width, the magnitude of magnetization, and the frequency stability.

Factors that determine frequency stability include the magnitude of magnetization and the temperature coefficient of the magnetic anisotropy constant.

The factors that determine the temperature stability of frequency will be described in detail below.

As is well known, the magnetic resonance angular frequency ω is given by the following equation.

ω=γ(Ho-4g(Nz Nt)MS+HA)
-(1) where γ is approximately 2.8 MHz/Oe (
Ho is a constant having a value of (Oersted) and is a magnetic field applied from the outside.

Nz and Nt are demagnetizing field coefficients in the magnetic field direction and the direction perpendicular thereto, and depend on the shape of the magnetic material.

For example, for a ball with a spherical shape, N z = N t
, for a sufficiently thin and flat shape, Nt<<N==1.

Therefore, in the case of a spherical element, the second term on the right side of equation (1) is O, and the resonance angular frequency ω does not depend on the magnetization Ms.

HA is an anisotropic magnetic field, and in the case of polycrystals, this term becomes zero.

In the case of a single crystal, VQ can be achieved by applying a magnetic field Ho in an appropriate direction of the crystal axis.

Since the magnetization MS and the anisotropic magnetic field HA are temperature dependent, the magnetic resonance angular frequency ω changes with temperature according to equation (1).

Therefore, from what was stated above, in a spherical polycrystalline body, (1
) is often used because the second term on the right side of the equation is O and the third term is quite small, so the temperature change in ω is small.

However, when used at a relatively low frequency of 3 GHz or less, for example, the so-called Suhl instability condition expressed by equation (2) becomes a problem.

ω> 21Nt 4 πMs (2) In order to satisfy this condition, the shape of the magnetic material should be made flat, or
Alternatively, it is a well-known fact that the magnetization MS of a magnetic material is reduced.

However, since N t << N z '' 1 in a flat-shaped element, ω is the magnetization Ms as seen from equation (1).
changes significantly as the temperature changes.

For example, in the case of normal CaV garnet, it is 1
4 MHz/'C (also null for 0.4%/'C).

However, the frequency stability required for the device is, for example,
In the case of UHFTV tuner, it is 0.23MHz/
'C, 0.1 for microwave circulators
%/°C and the material's inherent temperature change of 14 MHz/°C, which is very small.

In order to avoid this difficulty, the following methods have been considered.

(1) Place the entire device into the "Han-tan" bath.

(il) A material with a small magnetization Ns is used in the form of a sphere.

However, (1) requires very expensive equipment and is not very practical.

In addition, (ii) means that there is a lower limit to Ms's dog behavior, and Ms
The problem is that the efficiency decreases as the value decreases.

The present invention has been made in view of the problem that magnetization Ms.
An object of the present invention is to provide a novel material whose temperature coefficient is sufficiently small near room temperature and whose magnetic resonance width is small enough to utilize magnetic resonance phenomena.

Next, the principle of the present invention will be described in detail below.

The temperature change of magnetization Ms has already been described in US Patent 3.13.
2,105 GdzY3 zFe5 yAly01
There is an invention of magnetic garnet with two compositions.

Another example is A. Nis Hudson (A-S.H.
udson) Y3-2 x-a Ca2 x Ggo2a Fe5
Report on the material X 'J Z InzVxAy012 (I.E.).

E・E; Transaction on Magnetics (■・EE-E-Trans, onMag) ■o1M
AG-5. /I63, 1969. According to this data, materials with small temperature coefficients are
It has a relatively large magnetic resonance width.

Therefore, it has been thought that the magnetic resonance width of garnet in which yttrium (hereinafter referred to as Y) is usually replaced with gadolinium (hereinafter referred to as Gd) increases significantly with the amount of substitution.

However, as a result of research, by replacing Y with Gd and at the same time replacing part of Fe with indium (hereinafter referred to as In) and vanadium (hereinafter referred to as V), the temperature characteristics of magnetization could be improved without increasing the magnetic resonance width. I was able to improve it.

The reason why the magnetic resonance width ΔH becomes small will be explained below using FIGS. 1 and 2.

FIG. 1 shows Y as a typical example of the relationship between the amount of In substitution and the magnetic resonance width ΔH.

, 2Gd2. . CaO・8 Fe4-6-yIny v
Experimental results for O84012 are shown.

As can be seen from this figure, the magnetic resonance width ΔH decreases as In increases, and takes the lowest value at a value of 0.5 to 0.6.

This result does not depend on the amount of Gd when Gd is 0.1
/Molecular formula~2.2/All GdzY2.2-Z of molecular formula
Cao, 8Fe4.6-yInyVo, 40,2.

In FIG. 2, Yo, 2Gd2. □ Ca2 x Fe4.5-xIn
□ shows the experimental results of 5Vx012.

Regarding the amount of ■, it is similar to the case of In, and ■ is 0.2
The magnetic resonance width becomes small between /molecular formula and 0.7/molecular formula.

As described above in the representative examples shown in FIGS. 1 and 2, when V is 0.
47 molecular formula, Gd is 1. In the case of O/molecular formula, △H is 5
It has been found that it is possible to make it as small as 0e (Oersted) or less.

Next, the temperature coefficient αm will be described.

Here, the temperature coefficient αm was calculated using the following formula.

In addition, Ms (15°C), M3 (20°C), MS (2
5°C) are the magnitudes of magnetization at temperatures of 15°C, 20°C, and 25°C, respectively.

Figure 3 shows Gdzy2.2Z CaO-8Fe4-II
FIG. 3 is a diagram showing the relationship between the amount of Gd replaced by n□-5VO-4012 and the temperature coefficient of magnetization.

In the figure, data of the temperature coefficient 1 of magnetization Ms and the magnetic resonance width ΔH2 are written simultaneously.

From this figure, it can be seen that the temperature coefficient decreases as the amount of Gd substitution increases, and becomes WO when Gd is 2.2/molecular formula.

The magnetic resonance width ΔH increases as the amount of Gd substitution increases, but it becomes at least 50e or less.

FIGS. 4 and 5 are diagrams showing range 3 in which the temperature coefficient is O when In is 0.5/molecular formula and 0.6/molecular formula.

From this figure, the amount of Gd that makes the temperature coefficient zero is V, I
It can be seen that it depends on the amount of n.

Next, regarding the quantities of G d and V t I n, Fig. 1,
This will be described in detail using FIGS. 2, 4, and 5.

First, these amounts must comply with conditions determined by the crystal structure (garnet type) of this material and the principle of charge neutralization.

These conditions are well known and can be expressed for this system as follows.

First, according to the principle of neutralization, whenever 4 is replaced with XFe3+, it becomes necessary to replace Y3+ with 2X Ca2+.

Therefore, the composition of Ca is automatically determined to be 2x from the substitution amount X of (2).

Next, from the condition that Gd, Y, and Ca are in the same crystallographic position, the following equation is obtained: amount of Gd + amount of Y + amount of Ca = 3/3 + formula.

As a result, if Gd is determined to be z, and Ca is determined to be 2x, then Y
The amount of is 322xM.

This condition has already been stated as self-evident in the molecular formula.

On the other hand, from this condition, the maximum substitution amount Zmax of Gd when X is given is determined.

Obviously, when the amount of Y is "O", the amount of Gd is maximum, so 32 x z max=Oo Therefore, this satisfies the following condition.

Next, limiting conditions for XIyPZ arise from the conditions for obtaining good characteristics.

First of all, in order to reduce the magnetic resonance width ΔH, from Fig. 1, from Fig. 2, and from Fig. 4 and Fig. 5, the conditions related to temperature characteristics, the equation) is as follows: straight line x-=0.5z+1.5 and straight line X=0.5
From the condition of being surrounded by z+1.4, the lower limit of 2 depends on the amount of In in formula (e), and // 1. Bj/
.

It is obtained from the condition of "2.0".

Here, the condition in the formula) does not violate the more fundamental condition (a), so the condition in the formula holds true as is.

To summarize the above, under the following conditions, the temperature characteristics are approximately "O"'
A magnetic material with a large magnetic resonance width ΔH and a significantly small magnetic resonance width ΔH can be obtained.

Next, the present invention will be explained in detail with reference to Examples.

Examples The material for obtaining the magnetic material of the present invention is iron oxide (Fe2
03) 42.521 g, gadolinium oxide (Ga20
3) 52.364 g, indium oxide (■n20
3) 9.035g vanadium oxide (V205) 4.7
54 g, calcium carbonate (CaCOs) 10.
456 g of each powder was used.

All of these have chemical purity of 98% or more.

Especially when Gd203 (!11'203 is included, ¥2
03) and 99.99% Fe2O3 were used.

The raw materials are mixed in a ball mill, and the mixed powder is heated at 900℃ for 1
Calcined for an hour.

After the calcined body was pulverized, a small amount of water was added, a pressure of 1 tor+/- was applied, and the calcined body was pressure-molded into a disk with a diameter of 151 m, and then calcined at 1420° C. in an oxygen atmosphere for 3 hours.

The composition of the obtained magnetic material was Gd2. ．． 2cao-8Fe4.1inO-5vO”
4 o12.

The magnetization of this fired body was 430G (Gauss), the temperature coefficient of magnetization was 0%/° C. at room temperature, and the magnetic resonance width was 50e (Oersted).

As a result of using this material in a circulator with a center frequency of 1.4 GHz, the operating temperature range is -10°C to +50°C.
A product with a center frequency stability of 0.1%/°C or less was obtained.

This frequency stability cannot be achieved with conventional materials, and in the past, circulators had to be placed in a constant temperature bath, which was inconvenient.

As explained above, according to the present invention, a microwave element or device having significantly better temperature stability than the conventional one can be easily obtained.

[Brief explanation of drawings]

Figure 1 shows YO=2Gd2'OCao, 8Fe4.6-y
FIG. 2 is a diagram showing the dependence of the magnetic resonance width ΔH of InyVO'4012 on the amount of In substitution. oy,,2C
a2 xFe4.5 I I
FIG. 3 is a diagram showing the relationship between the magnetic resonance width ΔH and the temperature coefficient of the no.5Vo401□ system. Figure 4 also shows that In is 0.5/temperature coefficient O in the molecular formula.
Fig. 5 shows a composition distribution diagram of V and Gd which gives a temperature coefficient O in In 0.6/molecular formula.

Claims (1)

[Claims] I Gd zY, 2 x-zCa2 xFe5 x
In the magnetic material with the composition ylnyVx012, 0.2 < x < 0.7 and 0.4 < y < 0.
6 and 2.8-2 x<z<3-2 x and 2 y +
A magnetic garnet characterized by having a composition in the range of 0.8 < z.