JPH07157313A - Production of calcium-vanadium based ferrimagnetic garnet - Google Patents

Abstract

PURPOSE:To prevent the leaching of Ca and V in a production process and obtain a product free from unevenness in compsn. with a high reproducibility by previously converting at least CaCO3 and V2O5 among starting materials into a slightly water-soluble compd. by dry mixing and burning. CONSTITUTION:When magnetic garnet represented by the general formula (YaCa3-a) (Fe5-b-c-dInbVcAld)O12 (where 0.1<=a<=2.9, 0.0<=b<=0.5, 0.1<=c<=1.5 and 0.0<=d<=0.8) is produced, powders of Y2O3, CaCO3, Fe2O3, In2O3, V2O5 and Al2O3 as starting materials for the garnet are dry-mixed and burnt at >=950 deg.C to form a slightly water-soluble garnet phase and then wet mixing, burning and firing are carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a calcium-vanadium ferrimagnetic garnet used for a high frequency circuit element.

[0002]

2. Description of the Related Art A magnetic substance used in a high frequency circuit element, particularly a microwave circuit element, has an arbitrary saturation magnetization (4πM).
s), and the full width at half maximum of ferromagnetic resonance (ΔH)
Is required to be small, and magnetic loss and dielectric loss are low. Furthermore, in terms of the temperature characteristics of the high frequency circuit element, 4π
It is desired that the temperature coefficient (β) of Ms be extremely small.

At present, yttrium-iron-based garnet, calcium-vanadium-based garnet, manganese-magnesium spinel-based ferrite and the like are known as magnetic materials used in the high frequency band, particularly in the microwave band and quasi-microwave band. .

Of these, yttrium-iron garnet is a low loss material as compared with the conventional spinel ferrite, and can be set to an appropriate 4πMs by Al substitution.
Since the temperature coefficient (β) of 4πMs can be reduced by d substitution, it was most often used as a magnetic material for high frequency circuit elements.

On the other hand, calcium-vanadium garnet is a material having a lower loss than yttrium-iron garnet, and it has an appropriate 4π by Al substitution.
Since it can be set to Ms and the temperature coefficient β of 4πMs can be reduced by Gd substitution or the like, it is superior to yttrium-iron-based garnet as a magnetic material for high frequency circuit elements.

[0006]

However, as will be described in detail below, since the composition of the magnetic material material is deviated in the manufacturing process, it has not been used so much. First,
This calcium-vanadium-based magnetic garnet was generally manufactured as follows. That is, the raw materials Y ₂ O ₃ , CaCO ₃ , Fe ₂ O ₃ , In ₂ O ₃ and V ₂
The O ₃ and Al ₂ O ₃ powders are wet mixed. next,
It was dehydrated and dried, calcined, crushed, then compression molded, and then fired at a temperature of 1300 to 1500 ° C.

In the raw material of this calcium-vanadium garnet, V ₂ O ₅ is about 0.007 g / water.
1 liter is dissolved and the solution shows acidity. Furthermore, Ca
CO ₃ easily liberates CO ₂ by the action of its acidic aqueous solution, and the produced CaO reacts with H _{2 O} to produce Ca (OH) ₂ having a solubility in water of about 0.126 g / liter. Therefore, according to the conventional method for producing a calcium-vanadium garnet, when the raw material powder is wet mixed, Ca
And V elute and composition shift occurs, and C
The calcium-vanadium-based magnetic garnet has a composition in which the amounts of a and V are small. The amounts of Ca and V that decrease due to this elution differ depending on changes in water temperature during wet mixing, and therefore cannot be accurately predicted, and it is very difficult to obtain a calcium-vanadium magnetic garnet with good reproducibility. I had a problem.

Therefore, the object of the present invention is to obtain a calcium-vanadium-based ferrimagnetic garnet obtained by molding and firing a mixture of raw material powders, for example, the general formula {Y _a Ca _3-a }.
[Fe _5-bcd In _b V _c Al _d ] O ₁₂ (however, 0.1
≦ a ≦ 2.9, 0.0 ≦ b ≦ 0.5, 0.1 ≦ c ≦ 1.
5,0.0 ≦ d ≦ 0.8), it is to provide a manufacturing method in which Ca and V do not elute in the manufacturing process to cause compositional deviation.

[0009]

In order to achieve the above object, a method for producing a calcium-vanadium ferrimagnetic garnet according to the present invention is a method for producing a calcium-vanadium ferrimagnetic garnet in which a mixture of raw material powders is molded and fired. In advance, at least CaCO among the raw materials of the calcium-vanadium ferrimagnetic garnet
₃ and V ₂ O ₅ are dry-mixed and calcined to obtain a water-insoluble compound.

Further, calcined by molding a mixture of raw material powders, the general formula _{{Y a Ca 3-a}} [Fe 5-bcd In b V c
Al _d ] O ₁₂ (however, 0.1 ≦ a ≦ 2.9, 0.0 ≦ b
≦ 0.5, 0.1 ≦ c ≦ 1.5, 0.0 ≦ d ≦ 0.8)
In the production of the calcium-vanadium-based ferrimagnetic garnet represented by the formula, Y ₂ O ₃ , CaCO ₃ , and F which are raw materials of the calcium-vanadium-based ferrimagnetic garnet
Powders of e ₂ O ₃ , In ₂ O ₃ , V ₂ O ₅ and Al ₂ O ₃ are dry-mixed and calcined at 950 ° C. or higher to form a hardly soluble garnet phase in water, and then wet. It is characterized in that it is mixed and calcined and then fired.

[0011]

According to the manufacturing method of the present invention, at least CaCO ₃ and V ₂ O ₅ are mixed in advance by a dry method, and then calcined to form a compound hardly soluble in water, for example, a garnet phase, so that they are mixed by a wet method. CaCO ₃ or V ₂ O in the process
₅ does not dissolve in water to cause compositional deviation.

[0012]

【Example】

(Examples) Examples of the method for producing a calcium-vanadium-based ferrimagnetic garnet of the present invention will be described below. First, Y ₂ O ₃ and C, which are raw materials, were used so as to obtain a calcium-vanadium-based ferrimagnetic garnet having the composition shown in Table 1.
aCO ₃ , Fe ₂ O ₃ , In ₂ O ₃ , V ₂ O ₃ and A
The powder of l ₂ O ₃ was dry mixed to obtain 5 kinds of mixed powder. It should be noted that, in order to improve the degree of mixing between the respective raw materials during dry mixing, the average particle diameter of each raw material is about 1.2.
A raw material having a size of μm or less was used. As the dry mixer, a fixed container type mixer (high-speed flow type) was used to improve the degree of mixing. Further, in order to improve the slipperiness between the inner wall of the dry mixer and the raw materials, each raw material is sufficiently dried before compounding, and the organic powder as a sliding material is added to the raw material in an amount of 1%.
About 2 wt% was added.

Next, each of the five dry-mixed powders was calcined at 950 ° C. or higher at which a garnet phase was formed, and Ca
And V were made to be in the state of a compound sparingly soluble in water. When the calcination temperature is higher than 750 ° C and lower than 950 ° C, CaCO ₃ is
It is not suitable because it thermally dissociates into O to form water-soluble Ca (OH) ₂ .

Thereafter, each of the obtained garnet powders was wet mixed and ground, dehydrated and dried, and calcined again at 950 ° C. This is because the mixing and dispersion of the raw materials in the obtained garnet powder is insufficient only by dry mixing, so the calcined powder is wet-mixed and pulverized to be uniformly dispersed, and then calcined again. is there. In the wet mixing, a hard cobblestone and a pot were used to adjust the crushing time to obtain a desired crushed particle size and to achieve uniform dispersion.

Approximately 70 g of a polyvinyl acetate alcohol-based binder and 1500 ml of pure water were added to 700 g of each of the five types of garnet powder obtained by calcination again to disperse the binder. Then, this was dehydrated, dried at about 130 ° C. for about 24 hours, and passed through a # 40 mesh sieve to obtain an extremely fine garnet powder having a uniform particle size. About 1.5 ton / cm ^{2 of} this garnet powder
It was press-formed into a plate-like shape under pressure and was fired at 1300 to 1500 ° C. to obtain a calcium-vanadium-based ferrimagnetic garnet fired body. The above operation was repeated to obtain 15 lots of calcium-vanadium-based ferrimagnetic garnet fired body for each composition.

Next, the saturation magnetization (4πMs) and the ferromagnetic resonance absorption half-value width (ΔH) showing the degree of magnetic loss of these magnetic garnet fired bodies were measured. The results are shown in Table 1. In addition, the numerical value in the parentheses in the same table is the standard deviation σ _n-1 indicating the variation among 15 lots.

(Conventional Example) As a conventional example for comparison, a calcium-vanadium-based ferrimagnetic garnet fired body was obtained as follows. That is, the same Y ₂ O ₃ and CaCO as in the example
₃ , Fe ₂ O ₃ , In ₂ O ₃ , V ₂ O ₃ and Al ₂ O
The powder of No. ₃ was wet-mixed and pulverized with the same composition as in Example, dehydrated and dried, and calcined at 950 ° C. to obtain 5 kinds of garnet powder. In the wet mixing, a hard boulder and a pot were used in the same manner as in the examples to adjust the crushing time to obtain a desired crushed particle size and to achieve uniform dispersion.

Next, to each of 700 g of the five types of garnet powder obtained by calcination, about 70 g of a polyvinyl acetate alcohol-based binder and 1500 ml of pure water were added to disperse the binder. Then, this was dehydrated, dried at about 130 ° C. for about 24 hours, and passed through a # 40 mesh sieve to obtain an extremely fine garnet powder having a uniform particle size. About 1.5 ton / cm of this garnet powder
Press-molded into a plate with a pressure of ² , 1300-1500 ° C
Was fired to obtain a calcium-vanadium-based ferrimagnetic garnet fired body. The above operation was repeated to obtain 15 lots of calcium-vanadium-based ferrimagnetic garnet fired body for each composition.

Next, 4 of these magnetic garnet fired bodies were prepared.
πMs and ΔH were measured. The results are shown in Table 1. The numerical value in parentheses in the table is 15 as in the example.
It is the standard deviation σ _n-1 which shows the variation between lots.

[0020]

[Table 1]

As shown in Table 1, the lot-to-lot variation (standard deviation) of 4πMs and ΔH characteristics of the calcium-vanadium-based ferrimagnetic garnet obtained by the production method of the present invention is 4πMs as compared with that of the conventional method. And then 1/3 ~
It is extremely small, 1/4 to 1/37 in 1/4 and ΔH. Therefore, according to the method for producing a calcium-vanadium-based ferrimagnetic garnet according to the present invention, the conventional YI
It is understood that the calcium-vanadium-based ferrimagnetic garnet having extremely low magnetic loss as compared with G can be stably produced with good reproducibility.

In the above examples, all the calcium-vanadium-based ferrimagnetic garnet raw materials are dry-mixed and calcined at once to form a water-insoluble garnet phase. It is not limited only to this, but in the calcium-vanadium-based ferrimagnetic garnet raw material, at least only CaCO ₃ and V ₂ O _{5 which} are soluble in water are dry-mixed and calcined to give a compound that is hardly soluble in water. It goes without saying that the same effect can be obtained by the method of generating.

The composition of the calcium-vanadium ferrimagnetic garnet is not limited to the above-mentioned examples, but the general formula {Y disclosed in Japanese Patent Publication No. 56-31288.
_a Ca _3-a } [Fe _5-bcd In _b V _c Al _d ] O
₁₂ (However, 0.1 ≦ a ≦ 2.9, 0.0 ≦ b ≦ 0.5,
The same effect was obtained for all magnetic garnets represented by 0.1 ≦ c ≦ 1.5 and 0.0 ≦ d ≦ 0.8).

[0024]

As is apparent from the above description, the method for producing a calcium-vanadium ferrimagnetic garnet according to the present invention is a Y-, In-, Al-substituted system of calcium-vanadium ferrimagnetic garnet {Y _a C
_{a 3-a} [Fe 5} -bcd In b V c Al d] O 12 0.
1 ≦ a ≦ 2.9, 0.0 ≦ b ≦ 0.5, 0.1 ≦ c ≦
Regarding the composition represented by 1.5 and 0.0 ≦ d ≦ 0.8,
At least CaCO ₃ and V ₂ O ₅ are dry-mixed, and then calcined to form a poorly water-soluble compound, whereby CaCO ₃ or V ₂ O ₅ is dissolved in water during the production process to cause a composition shift. There is no such thing.

Therefore, a calcium-vanadium-based ferrimagnetic garnet having a magnetic loss lower than that of the conventional yttrium-iron-based garnet and exhibiting an appropriate saturation magnetization (4πMs) and an appropriate temperature coefficient (β) can be reproducibly stabilized. Can be manufactured.

Claims (2)

[Claims] 1. In the production of a calcium-vanadium ferrimagnetic garnet in which a mixture of raw material powders is molded and fired, at least CaCO ₃ and V ₂ O ₅ among the raw materials of the calcium-vanadium ferrimagnetic garnet are previously dry-processed. A method for producing a calcium-vanadium-based ferrimagnetic garnet, which comprises mixing and calcining to obtain a compound that is sparingly soluble in water. 2. A mixture of raw material powders is molded and fired,
Formula _{{Y a Ca 3-a}} [Fe 5-bcd In b V c Al
_d ] O ₁₂ (provided that 0.1 ≦ a ≦ 2.9, 0.0 ≦ b ≦
0.5, 0.1 ≦ c ≦ 1.5, 0.0 ≦ d ≦ 0.8), which is a raw material of the calcium-vanadium ferrimagnetic garnet in the production of the calcium-vanadium ferrimagnetic garnet. Y ₂ O ₃ , CaCO ₃ , Fe
Powders of ₂ O ₃ , In ₂ O ₃ , V ₂ O ₅ and Al ₂ O ₃ are dry-mixed and calcined at 950 ° C. or higher to form a sparingly soluble garnet phase in water, and then wet-mixed. A method for producing a calcium-vanadium-based ferrimagnetic garnet, which comprises firing after calcination.