JP3042088B2 - Single crystal manufacturing method - Google Patents

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 single crystal suitable for producing a multi-component single crystal such as ferrite.

[0002]

2. Description of the Related Art Conventionally, as a method for producing various single crystals, the Bridgman method, which is easy to operate and has simple equipment, has been widely used. In the Bridgman method, crystallization is promoted by using a temperature gradient. For example, one end of a molten sample is cooled and crystallized, and this is gradually grown. In the Bridgman method, it is customary to increase the probability of single crystallization by inserting a seed crystal into the crucible apex.However, in order to improve productivity, the ingot has to be made larger and longer. It is planned.

[0003]

However, in the conventional single crystal manufacturing method described above, when growing a large single crystal, the temperature condition of the solid-liquid interface at which crystallization occurs depends on the heat capacity and the size of the single crystal itself. For this reason, the crystal growth disadvantageously changes, and as a result, there is a problem that a crystal grain boundary and a bending of a crystal orientation are generated, which significantly adversely affects the crystallinity.

The present invention has been made in view of such problems, and provides a method capable of greatly improving the probability of single crystallization and obtaining a single crystal having excellent crystallinity. The purpose is to:

[0005]

Production method of the present invention a single crystal, there is provided a resolving means for] is a crucible raw material of the melt state is maintained, the temperature
Crystals are slowly passed through a furnace with a gradient
In the method for producing a single crystal for growing
It is a feature. (A) The cranial point of the crucible is
Keep and protect with refractory. (B) The refractory is substantially cylindrical
The bottom surface of one of the cylinders has the refractory and the
Processed so that the pointed head can always be in close contact
You. (C) The refractory has a diameter equivalent to the diameter of the crucible.
With a diameter of 1 to 1.5 times the diameter of the crucible.
Have. Further, the method for producing a single crystal of the present invention,
A crucible holding raw materials is placed in a furnace with a temperature gradient.
A single crystal that grows by gradually passing through
A method for producing a crystal, characterized by the following:
It is. (B) Keep the crucible head warm with refractory
And protect. (B) The refractory has a substantially cylindrical shape.
On one bottom side of the pillar, the refractory and the pointed head are always
It is processed so that it can be in close contact. (C) The above resistance
The fire has a diameter of 0.8 to 1 times the diameter of the crucible,
And has a height approximately equal to the diameter of the crucible. In addition,
The production method for bright single crystals is that raw materials in the molten state are retained.
The crucible that passes through the furnace with a temperature gradient
In this way, a single crystal manufacturing method for growing a crystal
And is characterized by the following. (B) Above
The crucible tip is kept warm and protected with refractory. (B)
The refractory is substantially frustoconical, and one bottom of the frustum is
On the surface side, the refractory and the pointed head can always be in close contact.
Indeed, it has been processed. (C) The refractory is
One bottom surface has a diameter approximately equal to the diameter of the crucible, and the other
Has a diameter of 0.5 to 1 times the diameter of the crucible,
And has a height approximately equal to the diameter of the crucible.

[0006]

According to the method for producing a single crystal of the present invention, the crucible tip 1a is made of a refractory 4 having a substantially cylindrical or frusto-conical shape .
By maintaining and protecting the temperature, the probability of single crystallization can be greatly improved, and a single crystal having excellent crystallinity can be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for producing a single crystal according to the present invention will be described below with reference to FIGS.

FIG. 2 shows an example of an apparatus for realizing single crystal production by the Bridgman method.

First, a platinum crucible 1 as shown in FIG.
Is prepared, and the raw material 2 is put.

Next, as shown in FIG. 2A, the crucible 1 is installed at the center of the growth furnace, and the temperature of the growth furnace is raised to completely melt the raw material 2 to form a melt 2. Then, FIG.
The furnace is gradually lowered in a furnace having a temperature gradient as schematically shown on the right side.

Subsequently, when the crucible 1 is lowered, the lower end of the crucible 1 reaches a point X where the furnace temperature is the crystallization temperature, as shown in FIG. Is cooled below the crystallization temperature, and a single crystal 3 starts to crystallize from the lower end of the melt 2.

Finally, as shown in FIG. 2 (c), the crucible 1 is continued to descend until all of the melt 2 becomes a single crystal 3, and is gradually cooled to take out a rod-shaped single crystal 3.

At this time, in the present invention, the pointed tip of the crucible 1 is formed in a substantially cylindrical shape having a height h longer than the crucible diameter R and having a diameter r substantially equal to the crucible diameter R. The single crystal is grown while keeping the temperature and protection with the refractory.

According to this method, the probability of single crystallization of the obtained single crystal is greatly improved, and excellent crystallinity is obtained.

Here, the tip of the crucible 1 is shown in FIG.
(A) to (c) and a refractory (alumina brick) having a shape as shown in FIGS. For comparison, a ferrite single crystal was prepared even when nothing was attached to the point of the crucible 1.

As shown in FIG. 1, the crucible 1 is a cylindrical container having a conical bottom end and a seed crystal part 1b at the tip, and has a tube diameter (crucible diameter) of R. , The length is L, and the angle of the pointed head 1a is 90 °. It is assumed that the refractory 4 is processed and fixed to the pointed head 1a so that the refractory 4 and the pointed head 1a can always be in close contact with each other.

FIG. 3A shows a case where the diameter r of the cylindrical refractory is equal to the crucible diameter R and the height h is half of the crucible diameter R (Comparative Example 1), and FIG. When the diameter r of the cylindrical refractory is as small as 4/5 of the crucible diameter R and the height h is equal to the crucible diameter R ( Example 1 ), FIG. The upper diameter r is the crucible diameter R and the lower diameter r '
Is 1/2 of the crucible diameter R and the height h is equal to the crucible diameter R ( Example 2 ), FIG. 4A shows that the diameter r of the cylindrical refractory is equal to the crucible diameter R, When the height h is equal to the crucible diameter R (Example 3 ), FIG. 4B shows that the diameter r of the cylindrical refractory is equal to the crucible diameter R, and the height h is 1.5 times the crucible diameter R. when is longer (example 4), FIG. 4 (c) shows the case where without a refractory (Comparative example 2).

FIGS. 5 (a) to 5 (a) show the appearance of the surface of the single crystal obtained in each of the examples and comparative examples and the occurrence rate P of the crystal grain boundaries.
6 (c) and FIGS. 6 (a) to 6 (c). Note that the occurrence rate P of the crystal grain boundary is expressed as a ratio of the number of single crystals in which the crystal grain boundary is generated when 10 single crystals are manufactured in each of Examples and Comparative Examples. is there. FIG. 5A shows the single crystal obtained in Comparative Example 1, in which many crystal grain boundaries were observed from the seed crystal part, and the occurrence rate P of the crystal grain boundaries was 100%. FIG. 5 (b) shows the implementation
In the single crystal obtained in Example 1 , two to three crystal grain boundaries were observed from the upper end of the cusp, and the occurrence rate P of the crystal grain boundaries was 50%. FIG. 5C shows the single crystal obtained in Example 2 , in which one large crystal grain boundary was observed from the seed crystal part, and the occurrence rate P of the crystal grain boundary was 30%. FIG. 6A shows the single crystal obtained in Example 3 , in which the bending of the crystal grain boundaries and the crystal orientation was hardly recognized. FIG. 6B shows the single crystal obtained in Example 4 , in which no bending of the crystal grain boundaries or crystal orientation was observed. FIG. 6C shows the single crystal obtained in Comparative Example 2 , in which a large number of crystal grain boundaries and several cracks were observed from within the pointed tip to the rear end of the ingot, and the occurrence rate of the crystal grain boundaries was observed. P
Was 100%.

From FIGS. 5 (b) and 5 (c) and FIGS. 6 (a) and 6 (b), the probability of single crystallization of the obtained single crystal is improved, and the crystallinity is improved. Is obvious.

Summarizing the above, according to the method of this example, when growing a single crystal by the Bridgman method, the tip of the crucible is kept warm and protected by a substantially columnar or substantially frustoconical refractory. By doing so, the generation of crystal nuclei causing crystal grain boundaries can be suppressed, and growth from seed crystals can be promoted, so that the probability of single crystallization can be greatly improved, and crystallinity can be improved. Excellent single crystals could be obtained.

The present invention is not limited to the above-described embodiment, but can adopt various configurations without departing from the gist of the present invention.

[0022]

As described above, according to the present invention,
Since the generation of crystal nuclei causing crystal grain boundaries can be suppressed and growth from seed crystals can be promoted, the probability of single crystallization can be greatly improved, and single crystals with excellent crystallinity can be obtained. Is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a single crystal manufacturing apparatus used in this example.

FIG. 2 is a diagram showing a single crystal manufacturing process of the present example.

FIG. 3 is a diagram showing a refractory used in the present example.

FIG. 4 is a diagram showing a refractory used in this example.

FIG. 5 is a diagram showing a single crystal obtained in this example.

FIG. 6 is a diagram showing a single crystal obtained in this example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crucible 1a Pointed head 1b Seed crystal part 1c Point nose 4 Refractory

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C30B 1/00-35/00

Claims (3)

(57) [Claims] 1. A method for producing a single crystal, in which a crucible holding raw materials in a molten state is gradually passed through a furnace having a temperature gradient to grow a crystal , characterized by the following features. Single crystal production method. (B) Keep the crucible heads warm and protected with refractory
You. (B) The refractory is substantially cylindrical, and one bottom of the column
On the surface side, the refractory and the pointed head can always be in close contact.
Indeed, it has been processed. (C) The refractory has a diameter approximately equal to the diameter of the crucible.
And has a height of 1 to 1.5 times the diameter of the crucible
You. 2. Ruth holding raw materials in a molten state.
To gradually pass through the furnace with a temperature gradient.
According to a method for producing a single crystal for growing a crystal, a method for producing a single crystal characterized by the following. (B) Keep the crucible heads warm and protected with refractory
You. (B) The refractory is substantially cylindrical, and one bottom of the column
On the surface side, the refractory and the pointed head can always be in close contact.
Indeed, it has been processed. (C) The refractory is 0.8 to 1 times the diameter of the crucible.
It has a diameter and a height about the same as the diameter of the crucible.
You. 3. Ruth holding raw materials in a molten state.
To gradually pass through the furnace with a temperature gradient.
According to a method for producing a single crystal for growing a crystal, a method for producing a single crystal characterized by the following. (B) Keep the crucible heads warm and protected with refractory
You. (B) The refractory has a substantially frusto-conical shape.
On the bottom side, the refractory and the pointed head are always in close contact.
It has been processed so that it can be used. (C) In the refractory, the one bottom surface has a diameter of the crucible.
The diameter of the crucible is the same as that of the crucible.
0.5 to 1 times the diameter and about the same as the diameter of the crucible
With a height of