KR0157325B1 - Process and apparatus for mn-zn ferrite single crystal growth - Google Patents

Abstract

The present invention relates to a growth medium of manganese-zinc ferrite single crystals and a method for preparing manganese-ferrite single crystal using the same.

That is, the growth apparatus of the Nn-Zn ferrite single crystal of the present invention is a crucible transfer device, a platinum crucible capable of attaching seed crystals to the upper portion, a melting vessel and heating apparatus for melting raw materials, and controlling the cooling rate of the generated single crystal. It consists of bobo heating furnace and auxiliary heating device for shielding the molten raw material from the outside and preventing solidification. It has the form of single crystal to grow on the raw material dissolved inside the molten container and has a seed crystal attached on the top. By inserting a platinum crucible and pulling the crucible at a constant speed, a single crystal of uniform composition can be obtained, a large single crystal can be prepared, and the size of the available single crystal ingot can be increased per single crystal ingot.

Description

Mn-Zn Ferrite Single Crystal Growth Device and Manufacturing Method of Single Crystal Using Same

1 is a schematic structural diagram of a single crystal growth path of a Bridgeaann method used in the prior art,

2 is a schematic structural diagram of a single crystal growth apparatus of the present invention,

3 is a composition change diagram along the longitudinal direction of the single crystal ingot grown by the conventional Bridgemann method,

4 is a composition change diagram in the longitudinal direction of the single crystal ingot grown by the method of the present invention,

5 is a cross-sectional view of formation of cracks formed in a single crystal grown by a conventional method.

* Explanation of symbols for main parts of the drawings

-●-: Fe ₂ O ₃ ,-x-: MnO

-o-: Zn01 1,1 ': Crucible feeder

2: growth furnace 3,3 ': platinum crucible

4,4 ': seed crystal 5,5': auxiliary heating furnace

6: auxiliary heating device 7: heating device

8: melt container 9: single crystal ingot

10 crack

The present invention relates to an apparatus for growing manganese-zinc ferrite single crystals used as head materials of audio, VTR and computers, and a method for manufacturing manganese-zinc ferrite single crystals using the same.

The head material of the VTR is manufactured by using Mn-Zn ferrite, which has high permeability at high frequencies and excellent processability and durability, in a single crystal state, and gradually becomes Mn as a head for a rigid disk drive of a computer. Zn Ferra art single crystals are being used.

Conventionally, the Mn-Zn ferrite single crystal manufacturing method is a method using a single crystal growth furnace (2) of the Bridgemann type, as shown in Figure 1, that is, the seed crystal (4) and the raw material to the platinum crucible (3) After melting the raw material of the upper part including a part of the seed crystal (4) and lowering the crucible position, a method of growing single crystal or lowering the crucible position while rotating the crucible was used, but the upper part of the platinum crucible (3) Since the composition of the grown single crystal is changed because ZnO is evaporated from the molten raw material because it is exposed to the outside, it is difficult to produce a single crystal of the desired composition, and due to the difference in composition of the raw material Among the single crystal ingots, the characteristics were good and there was a disadvantage that the size of the available single crystal was small.

In addition, in the conventional method, due to structural problems, single crystals smaller than the size of the crucible are grown, and the upper part of the single crystals not only forms defects, particularly microcracks, but also single crystal growth by reduction and oxidation reactions in the outside air (atmosphere). Since the cost of platinum crucible used in the material cost and processing cost of the crucible occupy more than 50% of the total material cost, there is a disadvantage that the manufacturing cost is expensive because the effective length available in the single crystal ingot is short.

Accordingly, an object of the present invention is to provide a Mn-Zn ferrite single crystal growth apparatus, and another object is to provide a method for producing a Mn-Zn ferrite single crystal ingot having a uniform composition using the apparatus.

It is still another object of the present invention to provide a method for preparing Mn-Zn ferrite single crystal, which is suitable for the production of large single crystal and can increase the yield of single crystal.

In order to solve the above object, in the present invention, the crucible conveying apparatus (1 '), platinum crucible (3'), seed crystal (4 '), auxiliary heating furnace (5'), auxiliary heating cabinet (6), heating equipment ( 7) and Mn-Zn ferrite single crystals were prepared using a single crystal growth apparatus composed of a melting vessel (8).

The field name will be described in more detail based on the accompanying drawings.

As shown in FIG. 2, first, a large amount of raw material is melted using a resistance heating or induction heating method in a platinum melting container 8 by a heating device 7, and then a single crystal to be grown. The crucible 3 'is made in the ingot form and the platinum crucible 3' configured to attach the seed crystal 4 'is melted to a part of the seed crystal 4'. After positioning, the single crystal is grown from the seed crystal 4 'provided on the top of the platinum crucible 3' while pulling up the platinum crucible 3 'with rotation using the crucible feeder 1'. In this case, since the raw material grown as a single crystal is shielded from the outside by a crucible, ZnO cannot be evaporated and a single crystal with a uniform composition is grown.

On the other hand, the Mn-Zn ferrite growth apparatus of the present invention suppresses the formation of polycrystals from the crucible 9 'wall by attaching the auxiliary heating paper 6 to the boundary between the liquid phase in which the raw material is dissolved and the atmosphere. I was.

By passing the single crystal grown in the above-described manner through the auxiliary heating furnace, the cooling rate of the grown single crystal was controlled to prevent the grown single crystal from rapidly cooling.

It is preferable to perform pretreatment before putting a single crystal raw material into a melting container and melting it. For example, MnCO ₃ , ZnO, Fe ₂ O ₃ may be mixed, dehydrated, dried, calcined, and crushed to prepare a mixed powder of MnO, ZnO, Fe ₂ O ₃ .

The melting method of the raw material can be remelted by a conventional method, but it is effective to use an induction heating method or a resistance heating method.

By using the above-described Mn-Zn ferrite single crystal manufacturing method of the present invention, the size of the crucible can be increased to easily produce a large single crystal, and since the single crystal is formed up to the end of the crucible, the effect of increasing the size of the single crystal is obtained. Can be.

In addition, since the end of the single crystal is limited by oxidation and reduction reactions caused by contact with the outside air due to contact with the molten liquid, fine cracks are not formed at the end of the single crystal so that the entire single crystal ingot can be used.

The following examples and comparative examples will be described in more detail the Mn-Zn ferrite single crystal growth apparatus of the present invention and a method for producing Mn-Zn ferrite single crystal using the same, but is not intended to limit the scope of the present invention.

Example 1

MnCO ₃ , ZnO and Fe ₂ O ₃ are mixed and dehydrated and dried at 160 ° C for 8 hours, then calcined at 1250 ° C for 8 hours, water quenched and quenched and crushed to prepare raw materials. Manufacture.

During the calcination process during the manufacturing process, MnCO ₃ is decomposed into MnO and CO ₂ , blown off with CO ₂ gas and left as MnO. At this time, the composition ratios of MnO, ZnO and Fe ₂ O ₃ were 28 mol%, 18 mol% and 54 mol%, respectively.

This was put into the melting vessel (8), and then melted using a heating apparatus (7). A cylindrical crucible (3 ') having a diameter of 50 mm, a length of 280 mm, and a seed crystal (4') was provided at the top. A portion of the seed crystal 4 'is placed in the melting vessel 8 to the extent that it is melted, and then the single crystal is grown while pulling up at a speed of 4 mm / hour using the crucible feeder 1', and the auxiliary heating furnace 6 ' Cooling was adjusted while adjusting the cooling rate of the grown single crystal to 1.5 ° C / min to prepare a single crystal having a diameter of 50mm, length 250mm.

The prepared single crystals were cut at intervals of 15 mm in the longitudinal direction, and the composition change according to the length change was analyzed using EDAX, and the results are shown in FIG. 4, and the cross section was observed by cutting in the longitudinal direction of the single crystal ingot. Could not be confirmed.

Comparative Example 1

A single crystal was prepared in the same manner as in Example 1 except that the raw material was manufactured in the same manner as in Example 1 except that a Mn-Zn ferrite single crystal was manufactured using a conventional Bridgemann type single crystal growth furnace. As a result of analyzing the change of the composition according to the length change, the result is shown in FIG. 3, and the cross section cut in the longitudinal direction was observed. As shown in FIG. .

As can be seen from FIG. 3 and FIG. 4, in the case of the single crystal manufactured by the method of the present invention, the composition was slightly changed at about 20 mm from the tip of the ingot, but the composition was changed according to the length of the single crystal ingot. On the other hand, in the case of a single crystal manufactured by using a Bridgemann type single crystal growth furnace, the composition was severely changed according to the length change.

As described above, the single crystal prepared using the Mn-Zn ferrite single crystal manufacturing method of the present invention has a uniform composition, and by using the method and apparatus of the present invention, it is easy to prepare a large single crystal and defects of crystals, in particular, Single crystals could be prepared.

That is, the Mn-Zn ferrite single crystal manufacturing method of the present invention prevents evaporation of ZnO to obtain a single crystal having a uniform composition by shielding the molten raw material to be grown from the outside, unlike the conventional single crystal growth method. Has an effect.

In addition, due to the structural characteristics of the single crystal growth apparatus of the present invention, large single crystals can be easily manufactured and single crystals can be grown to the end of the crucible, thereby increasing the size of the effective single crystal ingots available per single crystal ingot.

Claims (2)

Crucible transfer site, platinum crucible for attaching seed crystals on top, melting vessel and heating device for melting raw materials, auxiliary heating furnace for controlling the cooling rate frame of generated single crystal, and shielding and solidifying molten raw materials from outside Mn-Zn ferrite single crystal growth apparatus, characterized in that consisting of an auxiliary heating device for preventing. The single crystal growing apparatus of claim 1 is used, but has a form of a single crystal to be grown on raw materials dissolved in the melting vessel, and a platinum crucible with a seed crystal attached to the upper portion thereof is rotated and the crucible is pulled up at a constant speed. The manufacturing method of Mn-Zn ferrite single crystal which uses.

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