JPS61146779A - Production of single crystal - Google Patents

Abstract

PURPOSE:To obtain a single crystal of large size with a good yield by mirror- polishing the bonding surfaces between a polycrystal and a single crystal, interposing an acid between the polished surfaces, bonding the polycrystal and the single crystal, keeping the crystals in a bonded state at a prescribed humidity and then heating. CONSTITUTION:The bonding surface of the polycrystal block made of ferrite consisting of, by mol%, 20-40 MnO, 5-30 ZnO and the balance Fe2O3 is polished with diamond abrasive grain, after that the single crystal having the bonding surface dimension and the composition identical to those of the polycrystal is bonded to the polished surface of the polycrystal. A strong acid such as hydrochloric acid, etc., is then dropped onto both the bonding surfaces and both the crystals are kept in >=70% relative humidity atmosphere for >=2hr, then heated up to a fixed temp. at which no growth of discontinuous crystal particles of polycrystals takes place, thus all the polycrystals are converted into single crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to uniform single crystallization of polycrystals,
In particular, the present invention relates to a method of manufacturing single crystal ferrite useful for magnetic heads such as VTRs.

(Prior art) Conventionally, as a method for producing single crystals, the applicant has
No. 162496 discloses a single crystal production method using a solid phase reaction method. In this manufacturing method, the joint surfaces of the single crystal and polycrystalline material are mirror-polished, and then they are joined using a strong acid such as hydrochloric acid or nitric acid, and the polycrystalline material is immediately heated to become a single crystal. was.

(Problems to be Solved by the Invention) The above-mentioned manufacturing method has advantages over single-crystal manufacturing methods such as the Bridgman method, such as mass production and lower cost of single-crystal products. It was difficult for the entire body to become a uniform single crystal, and there were cases where abnormal growth of polycrystalline crystals was observed due to poor attachment of the seed single crystal. Therefore,
This method has the disadvantage that the yield of single crystals is low and that large single crystals cannot be obtained.

Figures 2 (a) and (b) are perspective views showing typical examples of defects, respectively, where 1 is a seed single crystal, 2 is a polycrystal, 3 is a back dummy, 4 is an abnormal crystal growth part, and 5 is a The generated single crystal part is shown. In addition, Fig. 2 (a) shows the pasting of the seed single crystal;
Abnormal crystal growth that occurs due to insufficient deposition is also
Figure (b) shows abnormal crystal growth that occurs due to the poor material of the polycrystalline body 2.

An object of the present invention is to provide a method for producing a single crystal that can eliminate the above-mentioned problems, prevent abnormal growth of crystals due to poor seed attachment, etc., and obtain large single crystals with good yield. It is something to do.

(Means for solving the same layer point) The method for producing a single crystal of the present invention is to grow the single crystal in the direction of the polycrystal by contacting and heating the polycrystal and the single crystal. In the method of obtaining crystals, the joint surfaces of a polycrystalline body and a single crystal are mirror-polished, and an acid is interposed between the mirror-polished surfaces to join the polycrystalline body and the single crystal, and the polycrystalline body and the single crystal are joined together. The method is characterized in that the polycrystalline material is kept in an atmosphere with a relative humidity of 70% or more for at least 2 hours or more, and then heated to convert the polycrystalline material into a single crystal.

(Function) When a strong acid is applied to the bonding surface between a single crystal and a polycrystalline material, under certain conditions, a thin layer of metal salt (a thin layer of metal salt) is formed on the bonding surface. It is most desirable to obtain a single crystal by heating the single crystal and the polycrystal in a state where the single crystal and the polycrystal are firmly joined by a layer.

As a result of various studies, the present inventors have found that in order to achieve the above-mentioned state and obtain a desirable single crystal, it is advisable to age the single crystal and polycrystal for at least 2 hours in a relative humidity of at least 70% or more after joining. I understand. Here, relative humidity 7
Aging for 2 hours or more is required at 0% or higher.
This is because unless this condition is met, desired bonding cannot be achieved and abnormal growth of crystals due to poor seed attachment cannot be prevented.

(Example) Hereinafter, the present invention will be explained in detail based on examples.

Although the method for producing a single crystal of the present invention can be applied to polycrystals of any composition, the following compositions are actually preferred.

E Ferrite MnO20-40 mol% Zn 0
5-30 moA/% 1”e 20s Remaining (preferably 45-55%) ■ Ferrite Ni0. 15-40 mole% Zn0
15-40 mol% FezO3 remaining (preferably 45-55%) ■Garnet; 3Y203.5FezO for garnet
s, 3Y203 and 5A203, all of which can be manufactured by the method of the present invention.

The blending ratio is Y2O3: FezO5-3:5 or Y20s:AizOs-3:5.

■ Spinel: Spinel has a composition of MgO.Aizo3, and the blending ratio is M(IQ:AJ!zoi=1:1).

First, a polycrystalline block having the composition as described above is prepared, and its joint surface is mirror-polished with diamond abrasive grains. On the other hand, a single crystal with the same composition and a bonding surface of the same size is prepared as a seed, and the bonding surface is mirror-polished in the same manner. Thereafter, a strong acid such as hydrochloric acid or nitric acid was dropped onto both bonding surfaces to bond the single crystal and polycrystalline body. At this time, it is more suitable for single crystallization to prepare a dummy material made of a polycrystalline material that does not grow crystals, and to bond the polycrystalline material to the surface facing the single crystal via a mirror polisher and strong acid. Next, the zygote obtained by the method described above is heated at a relative humidity of 70% or more, preferably 8%.
It is maintained in an atmosphere of 0% or more for 2 hours or more, preferably 5 hours or more. Thereafter, the joined body is heated to a temperature lower than the temperature at which discontinuous crystal grain growth occurs in the polycrystalline body, thereby converting the entire polycrystalline body into a single crystal.

衷JLI Raw materials are manganese oxide obtained by roasting manganese carbonate with a purity of 99.9%, zinc oxide and ferric oxide with a purity of 99.9%, and the composition is Mn0-31 mol%, znQ
-16.5 mol%, Fe 203-52.5T:lLt
% and impurities include St 02 0.01% or less, T
Forming a formulation with i 02 0.05% or less, Ca OO, 005% or less, Na 200.003% or less,
It was fired at 1320° C. for 4 hours under equilibrium oxygen partial pressure to obtain a manganese zinc ferrite polycrystal.

From this ferrite polycrystal and a ferrite single crystal manufactured by the high-pressure Bridgman method having almost the same composition as the ferrite polycrystal, 70 x 30 x 5 times - and 70 x
A 30× O, 5 m-plate was cut out, and the joint surfaces of each were polished using diamond abrasive grains.

Thereafter, 6N hydrochloric acid was applied to the joint surfaces, and the polycrystalline ferrite plate and the single crystal ferrite plate were stacked on top of each other. Further, a dummy material made of polycrystalline ferrite, which does not undergo crystal growth, was prepared and bonded to the polycrystalline ferrite on the side opposite to the bonding surface of the single-crystal ferrite via a polishing bond using hydrochloric acid.

For this ferrite bonded body, the aging time and atmospheric conditions during aging (
Aging was performed by changing the relative humidity in the air. After aging, this bonded body was placed in a nitrogen atmosphere for 12 hours.
After heating at 50°C for 30 minutes, the temperature was maintained at 1350°C for 15 hours, which is a temperature below 1360°C at which discontinuous crystal grain growth of ferrite polycrystals occurs, to cause an in-phase reaction and produce a single crystal according to the present invention. I got it. The results are shown in Table 1 as the appearance rate (%) of completely single crystals.

Table 1 ■ Good product (completely single crystallized) ■ Defective product (not single crystallized) Also, based on the results in Table 1, the relationship between aging atmosphere (relative humidity), aging time, and non-defective product rate was As shown in the figure.

As is clear from Table 1 and Figure 1, the aging time of 2 hours or more, preferably 5 hours or more, and the aging atmosphere in the range of atmospheric relative humidity of 70% or more, which is the scope of the present invention, is suitable for seedlings. Good results have been obtained with less abnormal growth of polycrystalline ferrite due to insufficient adhesion.

(Effects of the Invention) As is clear from the above detailed explanation, according to the method for producing a single crystal of the present invention, a single crystal in which the entire polycrystalline body is completely single crystallized can be obtained in good yield. . Moreover, it is possible to obtain large single crystals and to improve the yield of single crystallization of polycrystals. Furthermore, the ferrite single crystal obtained by the method of the present invention can be suitably used as a magnetic head for a VTR.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between aging atmosphere (relative humidity) and aging time of the present invention, and Fig. 2(a),
(b) is a perspective view showing typical examples of defects. 1... Seed single crystal 2... Polycrystalline body 3... Back dummy 4... Abnormal crystal growth part patent applicant
Nippon Insulators Co., Ltd. 1st drawing - Zonge w4 c time

Claims (1)

[Claims] 1. A method for obtaining a single crystal by growing the single crystal in the direction of the polycrystal by contacting and heating the polycrystal and the single crystal, comprising: The joint surfaces are mirror-polished, and the polycrystal and single crystal are joined by interposing acid between the mirror-polished surfaces, and the joined polycrystal and single crystal are placed in an atmosphere with a relative humidity of 70% or more for at least 2 hours. A method for producing a single crystal, which comprises holding the polycrystalline material for a period of time or longer and then heating the polycrystalline material to form a single crystal. 2. The above-mentioned polycrystalline and single crystal bonded body was heated to a relative humidity of 80%.
The method for producing a single crystal according to claim 1, characterized in that the above atmosphere is maintained for 5 hours or more.