JPH07115994B2 - Method for producing single crystal ferrite - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method capable of producing a large amount of single crystal ferrite having a small composition segregation and a homogeneous and ordered crystal orientation with a high yield.

"Prior Art" In recent years, oxide-based single crystal bodies have been widely used in the field of electronic industry for magnetic head materials and various oscillating elements, or for various sensors. Conventionally known methods for producing this type of oxide-based single crystal are the Czochralski method and Bridgman method, which utilize the solidification phenomenon, or the hydrothermal synthesis method and high-temperature high-pressure reaction method, which utilize thermal reaction. ing.

However, in the conventional method, it takes a long time to grow a single crystal body, and segregation or crack generation occurs inside the manufactured single crystal body, or the ingot has a plurality of single crystal bodies. There is a problem that the product is divided into multiple bodies to cause polycrystallization and the product yield rate is low.

Therefore, as an example of a method for producing a single crystal that can solve these problems, a method disclosed in Japanese Patent Application Laid-Open No. 59-18188 has been proposed. In the method disclosed in the above publication, the side surface 1a of a rectangular parallelepiped single crystal ferrite 1 is brought into contact with the side surface of a rectangular parallelepiped polycrystalline ferrite 2 and the contact surface is pressed. In this method, the single crystal ferrite 1 is used as a seed crystal and the polycrystalline ferrite 2 is single crystallized.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, it is necessary that the side surface 1a of the single crystal ferrite 1 and the side surface of the polycrystalline ferrite 2 have substantially the same size. There is a problem that the size of such single crystal ferrite is limited.

Further, when an additive is added in order to improve the magnetic characteristics of the ferrite, the polycrystalline ferrite can be bonded to the single crystal ferrite, but there is a problem that the whole cannot be made single crystal.

The present invention has been made in view of the above problems, without the occurrence of segregation or cracks, moreover, the single crystal ferrite of the required size without being restricted by the shape and size of the single crystal ferrite to be a seed crystal It is an object of the present invention to provide a method capable of producing a high yield and producing a single crystal of polycrystalline ferrite mixed with an additive.

"Means for solving problems" Single crystal ferrite and this single crystal ferrite, is the same,
Alternatively, a single crystal ferrite is used which has a similar composition and is composed of a body portion having a larger circumference than the single crystal ferrite and a neck portion having a tapered front end surface which is integrally provided on the body portion. One surface is brought into contact with the tip of the neck part of the polycrystalline ferrite, pressure heat is applied to induce an interfacial reaction at the contact interface between the two, and both are integrated, and then the whole is enclosed in a deformable container. The whole is single-crystallized by heating from the outside of the container by hot isostatic pressing while the single-crystal ferrite and the polycrystalline ferrite are pressed against each other. Further, as a container for bringing the polycrystalline ferrite and the single crystal ferrite into contact with each other, a hollow storage portion for inserting the single crystal ferrite is provided, and further, a tapered shape having a larger diameter than the storage portion for storing the polycrystalline ferrite is provided. It is possible to use a capsule provided with the storage unit main body.

[Operation] In the present invention, a polycrystalline ferrite comprising a single crystal ferrite, a body having a waist circumference larger than that of the single crystal ferrite, and a neck portion provided integrally with the body and having a tapered front end surface is provided. Use, contact one surface of the single crystal ferrite with the front end surface of the neck of the polycrystalline ferrite, pressurize and heat to induce an interfacial reaction at the contact interface between the two, and integrate them, and then single crystallize. Polycrystalline ferrite, which has a larger circumference than single crystal ferrite, can be made into single crystals.

In addition, since the size of the single-crystal ferrite can be single-crystallized without being restricted by the size of the single-crystallized ferrite, the size of the single-crystal ferrite finally obtained by single-crystallization can Not limited to crystals. In the present invention, the amount of expensive single crystal ferrite used can be small. Further, in the present invention, since the contact interface between the single crystal ferrite and the polycrystalline ferrite can be made small, the stress acting on the contact interface at the time of joining by heating and pressing becomes small. Furthermore, since the polycrystalline ferrite and the single-crystal ferrite are sealed in the container and bonded, even if the polycrystalline ferrite contains an additive, the risk of volatilization of the additive component does not occur and the processing temperature is increased. This enables single crystallization.

Hereinafter, the method of the present invention will be described in detail with reference to FIG.

In the present invention, for example, it is inert at high temperature,
It is preferable to manufacture the single crystal ferrite by the procedure described below using the capsule A having a structure shown in FIG. 1 and made of a material such as platinum that can be deformed by pressure.

The capsule A shown in FIG. 1 is composed of a cylindrical housing main body 10 with one side being tapered, and a lid 11 that closes the other side opening of the housing main body 10. The storage unit body 10
Is a cylindrical body 10a, a tapered connecting wall 10b formed on one side of the cylindrical body 10a, and a bottomed cylindrical shape having an inner diameter smaller than that of the cylindrical body 10a extending at the tip of the connecting wall 10b. Storage part 10c
It consists of and. Further, the lid body 11 is a disc-shaped lid plate 11a that closes the opening of the cylindrical body 10, and a deaeration pipe 11b that penetrates the central portion of the lid plate 11a and is hung from the lid plate 11a.
It is composed of a flange portion 11c that is provided around the outer peripheral portion of the lid plate 11a.

To produce a single crystal ferrite using the capsule A, the same as the single crystal ferrite to be produced, or
Polycrystalline ferrite 12 (see FIG. 3) having the same composition ratio and having a shape that can be inserted into the capsule A, and the storage portion.
A rod-shaped single crystal ferrite 13 bonded body (see FIG. 3) having a size that can be inserted into 10c is prepared. Here, in order to obtain the joined body shown in FIG. 3, the single crystal ferrite 13 is formed at the center of one end face of the cylindrical polycrystalline ferrite 12 'as shown in FIG.
The two may be joined together by hot pressing so as to be erected vertically, and after the joining, a part of the polycrystalline ferrite 12 'may be cut by machining or the like to prepare. As a result, a joined body is obtained in which the single crystal ferrite 13 is integrated with the polycrystalline ferrite 12 including the cylindrical body 12a, the tapered neck 12b, and the tip surface 12c of the neck 12b.

Next, the joint body shown in FIG. 3 is inserted into the housing main body 10, the lid 11 is put over the opening of the housing main body 10 as shown in FIG. 1, the opening is closed, and the collar portion 11c is attached. After welding to the cylindrical body 10a, the degassing pipe 1b is evacuated from the degassing pipe 11b.
1b is crushed with a tool such as a hammer and vacuum sealed.

Next, this capsule A is hot isostatically pressed at 1000 ° C.
Up to about 50 kg / cm ² and apply a gas pressure of about 50 kg / cm ² , then raise the temperature from about 1000 ° C to about 1500 ° C over several hours to increase the gas pressure to 1000 kg / cm ^2. It is set to about cm ² and held for several hours (for example, 5 hours), and the single crystal ferrite is used as a seed crystal to single crystallize the polycrystalline ferrite. After this, the capsule A is removed by cooling to room temperature.

According to the method described above, it is possible to produce a single crystal ferrite having a shape and size corresponding to the housing body 10 of the capsule A, without being influenced by the size and shape of the single crystal ferrite 13 that is a seed crystal. it can. As mentioned above, the single crystal ferrite 13 and the polycrystalline ferrite 12 are contained in the capsule A.
By encapsulating and heat treating under pressure, a volatile substance can be treated without volatilizing, so that the heat treatment temperature can be set higher than in the past, and single crystallization can be smoothly performed. If the material is sealed in a container and single-crystallized at a high temperature as described above, even a polycrystalline ferrite containing an additive can be single-crystallized without volatilizing the additive element. In addition, since single crystal is formed under pressure, pores and the like inside the single crystal can be eliminated, and a single crystal ferrite without defects can be obtained.

[Examples] MnO 30 mol%, ZnO 17 mol%, Fe ₂ O ₃ 53 mol%, a diameter of 5 mm, a columnar single crystal Mn-Zn ferrite having a length of 20 mm, and the same composition as this single crystal Mn-Zn ferrite A cylindrical polycrystalline ferrite having a diameter of 100 mm and a length of 200 mm is prepared. Next, the single crystal Mn-Zn ferrite and polycrystalline Mn-Zn
Using a hot pressing method so that the ferrite could be bonded as shown in FIG. ² , it was treated at a pressure of 200 kg / cm ² at 1100 ° C. for 3 hours to obtain a bonded body.

Next, this joined body is enclosed in a platinum capsule of the size shown in FIGS. 4 and 5, and after vacuuming from the deaeration pipe, the deaeration pipe is crushed with a hammer or the like to seal the capsule. To do.

Next, the capsule was heated and pressed under the following conditions by hot isostatic pressing. First, the temperature was raised to 1000 ° C. at a rate of 300 ° C./hour under an argon gas pressure of 50 kg / cm ² . Then, heat at a rate of 100 ° C / hour from 1000 ° C to 1500 ° C, and when the temperature reaches 1500 ° C, the pressure of the argon gas is set to 10 ° C.
The pressure was set to 00 kg / cm ^2, and this state was maintained for 5 hours. After this,
It was cooled to room temperature at a rate of 250 ° C./hour, and during this cooling, the pressure was gradually lowered so that an atmospheric pressure argon gas atmosphere was obtained at 700 ° C.

After removing the capsule after performing the above treatment,
The polycrystalline ferrite inside was completely single crystallized.

"Effects of the Invention" As described above, the present invention has a single-crystal ferrite, a body portion having a waist circumference larger than the single-crystal ferrite, and a tapered front end surface integrally provided with the body portion. The polycrystalline ferrite consisting of the neck and one side of the single crystal ferrite is brought into contact with the front end of the neck of the polycrystalline ferrite, heated under pressure to induce an interfacial reaction at the contact interface between the two, and then integrated. Since it is single-crystallized, a polycrystalline ferrite larger than the single-crystal ferrite can be single-crystallized.
Therefore, a single crystal ferrite larger than the single crystal ferrite that becomes the seed crystal can be obtained.

In addition, it is possible to single crystallize a larger polycrystalline ferrite without being restricted by the size of the single crystal ferrite, so the size of the single crystal ferrite finally obtained by single crystallization is limited to the seed single crystal. Not done. In the present invention, the amount of expensive single crystal ferrite used can be small.
Further, in the present invention, since the contact interface between the single crystal ferrite and the polycrystalline ferrite can be made small, the stress acting on the contact interface at the time of joining by heating and pressing becomes small.

Next, the integrated single-crystal ferrite and polycrystalline ferrite are enclosed in a deformable container, and the single-crystal ferrite and polycrystalline ferrite are heated from the outside of the container by a hot isostatic press in a state of being pressed against each other, and the whole is heated. Is crystallized,
Since the volatilization of volatile components is suppressed and the heating temperature can be increased to raise the temperature to a single crystal, even a polycrystalline ferrite containing an additive can be easily made into a single crystal.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which polycrystalline ferrite and single crystal ferrite are inserted in a capsule used for carrying out an example of the method of the present invention, and FIG. 2 is a state in which polycrystalline ferrite and single crystal ferrite are bonded. FIG. 3 is a perspective view showing a state of the joined single crystal ferrite and polycrystalline ferrite after cutting, and FIG. 4 is a sectional view showing the dimensions of each part of the accommodating part body of the capsule. FIG. 5 is a perspective view showing the size of each part of the lid of the capsule, and FIG. 6 is a side view for explaining a conventional method for producing a single crystal. A: Capsule (container), 10 ... Storage unit main body, 10a ... Storage unit, 10b ... Connection part, 10c ... Insertion part, 11 ... Lid, 11a ... Lid plate, 11b ... Degassing Pipe, 11c …… Collar part, 12,12 ′ …… Polycrystalline ferrite, 12a …… Body part, 12b …… Neck part, 12c …… Tip surface, 13 …… Single crystal ferrite.

Claims (2)

[Claims] 1. A single crystal ferrite, a body having the same or a similar composition as that of the single crystal ferrite, and a body having a body circumference larger than that of the single crystal ferrite and a tapered shape integrally formed with the body. A polycrystalline ferrite consisting of a neck having a tip surface is contacted with one surface of the single crystal ferrite to the tip surface of the neck of the polycrystalline ferrite, and pressure heating is applied to induce an interfacial reaction at the contact interface between the two. , Then the whole is enclosed in a deformable container, and then the single crystal ferrite and the polycrystalline ferrite are heated from the outside of the container by hot isostatic pressing in a state of being pressure-welded to make the whole single crystal. A method for producing a single crystal ferrite, which is characterized in that 2. A container for contacting the polycrystalline ferrite and the single crystal ferrite with a hollow accommodating portion into which the single crystal ferrite is inserted, and a container having a diameter larger than that of the accommodating portion and accommodating the polycrystalline ferrite. The method for producing a single crystal ferrite according to claim 1, characterized in that a capsule having a constricted housing body is used.