JPH08143399A - Production of helical single crystal, device therefor and crucible - Google Patents

Abstract

PURPOSE: To obtain a helical single crystal. CONSTITUTION: A seed crystal 40 is dipped in a melt L through a nozzle 12 communicating with a raw material melting crucible 10, and then the seed crystal 40 is pulled up or down to produce a fibrous single crystal. In this case, the seed crystal is rotated around the axis A of rotation and moved toward the axis A. The method is effectively used for an oxide single crystal. The production device 20 is provided with a seed crystal holder 21, a connecting member 30 to place the holder 31 at a specified distance from the axis A of rotation, a mechanism 21 for rotating the connecting rod 30 around the axis A of rotation at a fixed speed, and vertical moving mechanism 23 for moving the rotating mechanism 21 toward the axis A of rotation at a fixed speed. A small-diameter nozzle 12 for making the melt in the crucible 10 communicate with the outside is formed as a crucible to melt a single crystal material, and the nozzle is directed horizontally or at an angle of 30 deg. to horizontal.

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 spiral single crystal, an apparatus for producing the same and a crucible.

[0002]

2. Description of the Related Art In recent years, LN (LiNbO₃), YAG
(Y₃Al_FiveO₁₂), LBO (Li₂B _FourO₇) Acids such as
The single crystal of the compound is an important material for optical communication such as optical communication.
It is a material that has been sought after. Single crystal growth of such oxides
In the synthesis method, research on growing a single crystal into a desired shape
Has been done. For example, single crystal fiber, capillary
Of alumina single crystal and rutile single crystal by the method (EFG method)
Nurturing can be mentioned. This capillary method is used in crucibles
Place a die with a capillary or slit in the center
Seed the melt rising by capillary action into the slit in the die.
It is pulled up using crystals. With this method
Single crystal grown, especially single crystal fiber,
It has been widely studied because it can be incorporated
There is.

[0003]

However, the shape of the fiber obtained by the growth method such as the above-mentioned capillary method is only linear in the related art. However, in recent years, applications of oxide single crystals have expanded, and spiral single crystals have also been required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a spiral single crystal, an apparatus for producing the same, and a crucible.

[0005]

In order to achieve the above object, the present invention provides the following method for producing a spiral single crystal, an apparatus for producing the same, and a crucible. (1) When a fibrous single crystal is produced by immersing a seed crystal in a melt through a nozzle communicating with the raw material melting crucible and then pulling or pulling down the seed crystal, the seed crystal is rotated around an axis of rotation. A method for producing a spiral single crystal, characterized in that the spiral single crystal is moved while being rotated. (2) The method for producing a spiral single crystal according to the above (1), wherein the direction of the nozzle is inclined from the horizontal direction by a predetermined angle, and the crystal axis of the seed crystal is matched with the angle of the nozzle. (3) The method for producing a spiral single crystal according to (1) or (2) above, wherein the direction of the axis of rotation is vertical. (4) The above (1) to (3), wherein the single crystal is an oxide crystal.
A method for producing the spiral single crystal described. (5) Seed crystal holder, a connecting member that separates the seed crystal holder from the rotation axis by a predetermined distance, a rotation mechanism that rotates the connection member around the rotation axis at a constant speed, and the rotation mechanism. And a vertical moving mechanism for moving the worm at a constant speed in the direction of the axis of rotation thereof. (6) A crucible for melting a raw material for a single crystal, wherein a narrow-mouth nozzle for communicating the melt inside the crucible with the outside of the crucible is provided, and the direction of the nozzle is set from the horizontal direction to 30 degrees from the horizontal direction. A crucible for the production of spiral single crystals.

[0006]

According to the method for producing a spiral single crystal of the present invention, in addition to the conventional vertical movement in the moving direction of the seed crystal, horizontal rotation is applied, whereby the spiral single crystal can be grown. It is a thing. In this case, the crucible is provided with a nozzle communicating with the inside in correspondence with the spiral drawing direction, and the horizontal direction or at a slight angle from the horizontal direction, and the crystal axis of the seed crystal coincides with the angle of this nozzle. It is effective to let

In order to cause the seed crystal to move, the apparatus for producing a spiral single crystal of the present invention has the above structure. Further, the crucible of the present invention corresponds to the rotation of the seed crystal and the movement in the direction perpendicular to this rotation so that the direction of the nozzle coincides with the moving direction of the seed crystal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic diagram showing a crucible and a manufacturing apparatus for manufacturing a single crystal according to the present invention. Crucible 1 made of platinum
Reference numeral 0 is for melting a single crystal raw material such as LN and storing the melt L therein, and is provided with a heater (not shown) for heating and melting the raw material. On the bottom surface of the crucible 10, a discharge port 1 that can communicate with the inside and discharge the melt to the outside
1 is provided, and a nozzle 12 that is inclined downward at a predetermined angle from the horizontal is connected to the discharge port 11. The inclination angle θ of the nozzle 12 as shown in FIG. 2 is selected at an angle corresponding to the desired pitch of the spiral single crystal or the like, but is usually in the range of 0 to 30 degrees with respect to the horizontal direction. Moreover, the inner diameter of the nozzle can be selected according to the outer diameter of the obtained spiral single crystal fiber, and is selected according to the application. The inner diameter of the nozzle is usually in the range of 7 μm to 1.5 mm. The nozzle may be integrated with the crucible or may be attached as a separate body. The material is preferably the same as that of the crucible, but another material may be used. Further, the nozzle may be equipped with a heater for heating.

Below the crucible 10 as described above, an apparatus 20 for producing a spiral single crystal is arranged. The manufacturing apparatus 20 includes a rotation drive device 21 having a rotation mechanism inside.
The rotary shaft 22 is rotatably supported on a vertical rotary shaft center A passing through the center of the rotary shaft 22.
The rotation shaft 22 is given a constant rotation speed by a rotation mechanism such as a motor in the rotation drive device 21. The rotary drive device 21 is disposed on the lift drive device 23, and the vertical drive mechanism in the lift drive device 23 causes the rotary drive device 21 to move.
Can be lowered or raised at a constant speed. The rotation speed of the rotation drive device 21 and the lowering speed of the elevating drive device 23 can be freely set by the control device 24.

An arm (connecting member) 30 inclined obliquely upward is attached to the tip of the rotary shaft 22, and a holder 31 for holding a seed crystal 40 is attached to the tip of the arm 30.
Is attached. As a holding means for the seed crystal 40, a usual holding means such as a chuck can be adopted. Also, the holder 3
No. 1 is configured so that the crystal axis direction of the seed crystal 40 can be adjusted, and as shown in FIG.
And the angle of the seed crystal 40 is adjusted so as to give an angle of θ with the horizontal direction. Here, the horizontal distance r between the tip edge of the nozzle 12 and the rotation axis A becomes the rotation radius, that is, the outer diameter of the obtained helix (indicated by R in FIG. 3), and the rotation axis 2
A descent rate of 2 approximately determines the pitch of the helix (indicated by P in FIG. 3). Therefore, the inclination angle θ of the nozzle 12 (attachment angle of the seed crystal) and the length of the arm 30 are determined in consideration of them. The horizontal direction of the nozzle 12 is preferably tangential to the circumference of rotation of the seed crystal. An after-heater 25 is installed so as to surround the obtained spiral single crystal.
The temperature can be controlled by the controller 24. The after-heater 25 can be composed of a platinum heating coil. After heater 2
5 can be omitted.

In order to grow a spiral single crystal using the crucible and the manufacturing apparatus, first, the crucible 10 is filled with a single crystal raw material and heated and melted. Next, the seed crystal 40 held by the holder 30 of the manufacturing apparatus 20 is inserted from the tip of the nozzle 12, and the seed crystal 40 is immersed in the melt in the crucible 10 for growth. Then, by operating the manufacturing apparatus 20 and applying a constant descending speed while applying a constant rotating speed to the rotating shaft 22, the seed crystal is rotated and vertically descended, whereby the seed crystal is spirally formed. Move, Figure 3
The spiral single crystal 41 as shown in FIG.

In this case, the moving speed of the seed crystal (pulling speed)
Degree) is generally 1 to 120 mm / hr, and the descending speed is
Generally, it is in the range of 0.5 to 60 mm / hr. The present invention
The method for producing a filamentous single crystal is suitable for any type of single crystal.
Can be used, especially suitable for oxide single crystal
It Examples of this oxide include MgO and rutile (Ti
O₂), YAG (Y₃Al_FiveO₁₂), LBO (Li₂B
_FourO ₇), LN (LiNbO₃), LT (LiTa
O₃), GGG (Gd₃GaO₁₂), BGO (Bi₁₂G
eO₂₀), Crystal (SiO₂), Alumina (Al₂O₃)
Etc. can be illustrated.

Of course, the atmosphere during the production of the single crystal should be an atmosphere suitable for the single crystal. Also,
Although omitted in FIG. 1, a shutter may be installed around the rotation axis to separate the rotary drive device 21 and the elevating drive device 23 from the single crystal heat zone.

Next, a description will be given of an experimental example in which a spiral single crystal is specifically grown using the above apparatus. [Experimental Example] As a raw material, lithium niobate (LiNbO
_{Using 3} ), it was placed in a platinum crucible and heated and melted.
A seed crystal having an a-axis orientation tilted in the same direction was immersed in a nozzle having an inner diameter of 0.5 mm and tilted downward by 5 degrees with respect to the horizontal under the crucible to grow the seed crystal. 0.5 mm / min. The crystal axis was rotated with an inner diameter of 2 mm at a speed of about 3 mm. One rotation was made in about 12 minutes, and the pitch was about 1 mm. After growing for about 100 minutes, a spiral single crystal of 8 turns could be grown.

The spiral single crystal thus obtained can be expected to be used as, for example, a vibration sensor, an acceleration sensor, an optical switch, etc. by utilizing its spring-like shape. In this case, since the single crystal withstands high temperatures, the sensor can be used up to about 1200 ° C depending on the material.

In the present invention, the position of the nozzle of the crucible may be on the side surface of the crucible instead of on the bottom surface as shown in FIG. 4, and as shown in FIG. It may be provided on the liquid surface. In the latter case,
A helical single crystal can be obtained by imparting a rotational movement to a conventional pulling apparatus.

The present invention is not limited to the above embodiment. For example, the rotation drive mechanism and the elevation drive mechanism may be integrated, and the shape of the arm, the rotation shaft, and the like may be variously changed within the scope of the invention.

[0018]

According to the method and the apparatus for producing a spiral single crystal of the present invention, it is possible to easily produce a single crystal having a helical shape, which has heretofore been unavailable. Further, the crucible of the present invention has a structure particularly suitable for producing a spiral single crystal.

[Brief description of drawings]

FIG. 1 is a schematic view of a crucible and a manufacturing apparatus for manufacturing a spiral single crystal of the present invention.

FIG. 2 is a schematic view showing a tilt angle of a nozzle provided in a crucible and a crystal axis direction of a seed crystal.

FIG. 3 is a perspective view showing a spiral single crystal obtained by the manufacturing method of the present invention.

FIG. 4 is a sectional view showing an example of the crucible of the present invention.

FIG. 5 is a sectional view showing another example of the crucible of the present invention.

[Explanation of Codes] 10 Crucible 11 Discharge Port 12 Nozzle 20 Single Crystal Production Device 21 Rotation Drive Mechanism 22 Rotation Shaft 23 Elevation Drive Mechanism 24 Controller 30 Arm (Coupling Member) 31 Seed Crystal Holder 40 Seed Crystal A Rotation Center r Radius of rotation L Melt θ Angle of inclination of nozzle to horizontal P Pitch of helix R Diameter of helix

Claims (6)

[Claims] 1. When a fibrous single crystal is produced by immersing a seed crystal in a melt through a nozzle communicating with a raw material melting crucible and then pulling or pulling down the seed crystal, the seed crystal is rotated around the axis of rotation. A method for producing a spiral single crystal, which is characterized in that the spiral single crystal is moved while being rotated around. 2. The method for producing a spiral single crystal according to claim 1, wherein the direction of the nozzle is tilted from the horizontal direction by a predetermined angle, and the crystal axis of the seed crystal is made coincident with the angle of the nozzle. 3. The method for producing a spiral single crystal according to claim 1, wherein the direction of the axis of rotation is the vertical direction. 4. The single crystal is an oxide crystal.
A method for producing the spiral single crystal described. 5. A seed crystal holder, a connecting member for separating the seed crystal holder from the rotation axis by a predetermined distance, a rotating mechanism for rotating the connection member around the rotation axis at a constant speed, An apparatus for producing a spiral single crystal, comprising: a vertical moving mechanism that moves the rotating mechanism in the direction of the axis of rotation at a constant speed. 6. A crucible for melting a single crystal raw material,
A nozzle having a narrow mouth for communicating the melt inside the crucible with the outside of the crucible is provided, and the direction of the nozzle is from horizontal direction to 3 from the horizontal direction.
A crucible for producing a spiral single crystal, characterized by being set at 0 degree.