JPS6045158B2 - Method for manufacturing thin plate-like single crystal ferrite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing single-crystal ferrite, and particularly to a method for producing thin-plate-like single-crystal ferrite in which any crystal orientation can be selected, the composition is uniform, and the yield is high.

Conventionally, single-crystal ferrite is produced by melting the raw material ferrite.
Bridgmann method, which involves gradual cooling and direct single crystallization, or low melting point PbO, PbF.

It is manufactured using the flux method, in which raw ferrite is melted in a melt such as, and gradually cooled and precipitated to form a single crystal. By the way, the advantage of the Bridgmann method is that large-sized single crystal ferrite can be obtained relatively easily, but since the melting point of ferrite is extremely high at around 1600°C, the heating device becomes large and expensive, and Since the chemical activity of the ferrite melt is high, there is a disadvantage that the crucible for holding the melt must be made of an expensive noble metal.
On the other hand, although the flux method has the advantage of being able to produce single crystals at relatively low temperatures, it still requires the use of a crucible made of precious metals due to the high chemical activity of the flux, and it also requires the use of crucibles made of precious metals such as PbO and PbF2 used for the flux. There are many low melting point substances that are harmful, and there is a problem in that they tend to evaporate during single crystal growth. The object of the present invention is to provide a method for manufacturing thin plate-like ferrite that improves the drawbacks of the conventional single-crystal ferrite manufacturing method.

According to the present invention, a pre-fabricated single crystal ferrite and a polycrystalline ferrite are brought into contact with each other, and heat treatment is performed at a relatively low temperature while applying pressure perpendicular to the contact surface. When joining (merging) the two through a solid phase reaction, the temperature and oxygen partial pressure conditions at the time of joining were made to be more oxidizable than the temperature and oxygen partial pressure conditions used for producing single crystal ferrite, and Temperature during manufacturing
By selecting a reducing property compared to the oxygen partial pressure conditions, polycrystalline ferrite can be merged and integrated into single crystal ferrite parts at a significantly faster rate, and this was discovered through various experiments. .

The present invention will be explained below based on examples.

Example 1 Mn0.60zn0.34Fe2.1.

Single-crystal ferrite with a composition of 04 was heated at 1700°C in air.
It was manufactured from the molten state of

Next, polycrystalline ferrite of the same composition was heated at 1400℃ and 1300℃.
It was manufactured by hot pressing at a firing temperature of 1200°C. The oxygen partial pressure during hot pressurization was 0.05 atm in both cases. Next, these single crystal ferrite and polycrystalline ferrite were combined, and a pressure of 0 kg/d was applied to both at 1300° C. and held for 1 hour to produce three types of bonded ferrite. The oxygen partial pressure during hot pressurization was 0.05 atm in both cases. Figure 1 shows MrlO. 6OznO. 34Fe2. l2
This is an equilibrium phase diagram of ferrite with a composition of O4. In Figure 1, A is the phase boundary, and the upper right of A is the phase boundary between ferrite and α-Fe2O.
The lower left of A is a single-phase ferrite region.

A, b, c, d, e, f, g are contained in ferrite (indicate the amount (weight %) of two Fe, sequentially 1.87
, 1.8, 1.7, 1.5, 1.3, 1.1, 0.9%
It corresponds to

As can be seen from Figure 1, the joining process was carried out 13
The conditions of 00℃ and oxygen partial pressure of 0.05 atm are conditions in which the concentration of Fe2+ decreases and the concentration of Fe3+ increases, that is, oxidizing conditions for single crystal ferrite and polycrystalline ferrite manufactured at 1400℃. Yes, this is a neutral condition for polycrystalline ferrite produced at 1300℃, and 120
Regarding polycrystalline ferrite produced at 0° C., this is a condition in which the concentration of Fe2+ increases and the concentration of Fe3+ decreases, that is, a reducing condition. FIG. 2 is a micrograph of the vicinity of the junction boundary of these three types of joined ferrites.

A: If the temperature and oxygen partial pressure conditions during bonding are oxidizing for single-crystal ferrite and reducing for polycrystalline ferrite, oxidizing for bright single-crystal ferrite and polycrystalline! When ferrite is neutral, C corresponds to oxidizing single-crystal ferrite, and oxidizing polycrystalline ferrite. In addition, a is the single crystal ferrite part, b is the polycrystalline ferrite part, 1 is the position of one boundary between the single crystal ferrite and the polycrystalline ferrite before joining, 2 is the boundary after joining, and 3 is the position of the boundary after joining. This is a layer of polycrystalline ferrite particles that is merged with a single crystal ferrite portion. As can be seen from Figure 2, when the temperature and oxygen partial pressure conditions during bonding are oxidizing for single crystal ferrite and reducing for polycrystalline ferrite (Figure 2 A), the single crystal ferrite part The thickness of the polycrystalline ferrite part merged with is approximately 200μ
It has reached m.

On the other hand, when single crystal ferrite is oxidizing, and polycrystalline ferrite is neutral or oxidizing (see Figure 2), the thickness of the polycrystalline ferrite part that is merged with the single crystal ferrite part during the bonding process is Very little. In addition,
The polycrystalline ferrite portion that has been merged with the single-crystalline ferrite portion by the bonding process can be clearly identified because there are many etch bits in this merged layer. As is clear from the above results, it is clear that the temperature and The oxygen partial pressure conditions are oxidizing compared to the temperature and oxygen partial pressure conditions when manufacturing single crystal ferrite, and the temperature and oxygen partial pressure conditions when manufacturing polycrystalline ferrite are oxidizing.
It can be seen that when the condition is reduced compared to the oxygen partial pressure condition, the polycrystalline ferrite portion is merged into the single crystal ferrite portion at a significantly faster rate, that is, it can be turned into single crystal ferrite.

Example 2 A single crystal ferrite having a composition of Mn0◆60zn0.34Fe2◆1204 was produced from a molten state at 1700° C. in air.

Next, polycrystalline ferrite having the same composition was produced by hot pressing at a firing temperature of 1200° C. in a gas stream with an oxygen partial pressure of 0.05 atm. After that, these single-crystal ferrite and polycrystalline ferrite were combined into 407! Rmφ×1TI! The pieces were finished to a size of Mt, and both were combined, and a pressure of 5 kg/Clt was applied at 1400° C. in a gas stream with an oxygen partial pressure of 0.05 atm, and maintained for 2 hours. When the thus produced bonded (merged) ferrite was cut, polished, and etched, all of the polycrystalline ferrite parts were merged into single-crystal ferrite. As explained above, according to the present invention, thin plate-shaped single crystal ferrite can be produced at a relatively low temperature without using an expensive precious metal crucible or using harmful substances.

Further, according to the present invention, since polycrystalline ferrite having a uniform composition is converted into a single crystal, there is an advantage that the composition of the obtained single-crystal ferrite becomes uniform.

Further, since the single crystal ferrite produced in advance is made into a single crystallized sheet, the crystal orientation of the obtained single crystal ferrite is the same as that of the sheet, that is, it is possible to obtain a single crystal ferrite having a desired crystal orientation. However, in the process of converting single crystal ferrite into components and circuit elements, single crystal ferrite is usually finished to a predetermined size, but according to the present invention, a single crystal ferrite having a predetermined size can be easily obtained. In addition, as can be easily inferred from the above explanation or examples,
The present invention can also be applied to ferrites having different compositions and component ratios.

In addition, in order to make the temperature and oxygen partial pressure conditions during bonding more reducible than those during polycrystalline ferrite production,
Even if the manufacturing temperature of polycrystalline ferrite and the bonding treatment temperature are the same, only the oxygen partial pressure conditions need to be reduced.

[Brief explanation of the drawing]

Figure 1 shows MrlO. ．． ZrXO. 34Fe2. l2O4
Figure 2 is a micrograph of single crystal ferrite obtained by joining (merging) polycrystalline ferrite and single crystal ferrite; C indicates cases in which a method other than the present invention was used.

Claims (1)

[Claims] 1. When producing single crystal ferrite by bringing single crystal ferrite and polycrystalline ferrite into contact and hot pressurizing them to form an interdiffusion layer through a direct solid phase reaction between the two, during the hot press A method for producing thin plate-like single crystal ferrite, characterized in that temperature and oxygen partial pressure conditions are selected to be oxidizing for single crystal ferrite as an element body and reducing for polycrystalline ferrite.