JPH08319191A - Production of oxide single crystal and device therefor - Google Patents

Abstract

PURPOSE: To provide a method for producing an oxide single crystal by a μ- pulling down method, capable of forming the good oxide single crystal by continuously pulling it down in spite of enlarging the size of a crucible or increasing the amount of its raw material. CONSTITUTION: This method for producing an oxide single crystal comprises melting the raw material of the oxide single crystal in a crucible 7, contacting a seed crystal 15 to the molten material 8 and growing the oxide single crystal 14 while pulling the molten material down by a μ-pulling down method. The device equipping a crucible 7 and a nozzle part 13 extended from the crucible 7, and installing a single crystal growing part 35 at the bottom end of the crucible 7, is used. The temperatures at the crucible 7 and the crystal growing part 35 are independently regulated each other.

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 an oxide single crystal and an apparatus therefor.

[0002]

2. Description of the Related Art Recently, as a method for growing an oxide single crystal, a method of forming a single crystal fiber by a so-called μ pulling down method has been attracting attention. "Electronic Research Institute News" 1
July 993 (522), pages 4-8, JP-A-4-4-2
In Japanese Patent No. 80891 and Japanese Patent Application Laid-Open No. 6-345588, by this method, niobate / potassium / lithium (K ₃ Li _2-2x Nb _{5 + x} O _{15 + x} , hereinafter referred to as KLN) and the like are used. The history of growing the crystal fiber is disclosed.

According to the above-mentioned article of "Electronic Research Institute News",
Electricity is supplied to a platinum cell or crucible for resistance heating. At the bottom of this cell, a melt outlet is formed, and a rod-shaped body called a melt feeder is inserted into this outlet, and the amount of melt supplied to the outlet is thereby,
It also controls the state of the solid-liquid interface. By adjusting the diameter of the melt outlet, the thickness of the feeder, the length of protrusion of the feeder from the outlet, etc., a thin KLN single crystal fiber is continuously formed. According to this μ pulling down method, a single crystal fiber having a diameter of 1 mm or less can be formed, and thermal strain can be reduced, convection in the melt can be controlled, and the diameter of the single crystal fiber can be easily controlled. It has the feature of being able to produce a small, high-quality single crystal suitable for the generation of second harmonics.

[0004]

DISCLOSURE OF THE INVENTION The present inventor has
We have been conducting research to mass produce KLN single crystal fibers and the like by the pull-down method. The most important mass production technique is to increase the size of the crucible to process a large amount of melt, and to pull the single crystal fiber from the crucible continuously for a long time. Therefore,
The present inventor increased the amount of powder to be added to the crucible up to about 5 g, increased the size of the crucible accordingly, supplied electric power to the crucible to generate heat, and melted the raw material powder in the crucible, I tried the micro pull-down method.

However, it has been found that it is extremely difficult to pull down the melt from the outlet to form a single crystal when the size of the crucible is increased and the melting amount of the powder is increased. Specifically, when the temperature of the furnace in which the crucible is installed is set to 900 ° C. or lower and the powder in the crucible is melted mainly by energizing the crucible, the crystal growth in the vicinity of the draw-out port can be performed well. I didn't understand. That is, when the power supplied to the crucible was increased, the melt melted at the outlet and was not crystallized, and when this power was decreased, the melt became solid near the outlet and the melt could not be withdrawn.

When the temperature of the above-mentioned furnace is raised above 900 ° C., the whole crucible is heated to a large extent due to the radiant heat from the furnace, and the temperature gradient in the vicinity of the outlet becomes very small. It was not possible to grow crystals continuously.

An object of the present invention is to continuously produce a good oxide single crystal even when the size of the crucible is increased or the amount of raw material is increased when the oxide single crystal is manufactured by the μ pulling down method. It is to be able to form by pulling down.

[0008]

A method for producing an oxide single crystal according to the present invention comprises: melting a raw material of an oxide single crystal in a crucible; bringing a seed crystal into contact with the melt; When growing an oxide single crystal while pulling downward, the crucible and a nozzle portion extending from the crucible are provided, and a single crystal growth portion facing downward is provided at the tip of the nozzle portion. It is characterized in that the temperature of the crucible and the single crystal growing portion are controlled independently of each other by using a manufacturing apparatus that is used.

Further, in the apparatus for producing an oxide single crystal according to the present invention, the raw material of the oxide single crystal is melted in the crucible, the seed crystal is brought into contact with the melt, and the melt is directed downward. When growing an oxide single crystal while pulling it down, the crucible, the nozzle portion extending from this crucible, the single crystal growing portion provided at the lower end of this nozzle portion, and the crucible and the single crystal growing portion are independent of each other. And a heating mechanism for temperature control.

The inventor of the present invention has been conducting research to increase the size of the crucible in order to establish a mass production technique of the oxide single crystal by the μ pulling down method. Separately equipped with a nozzle part extending from the crucible,
It has been conceived that a single crystal growing portion is provided at the lower end of the nozzle portion and the crucible and the single crystal growing portion are temperature-controlled independently of each other.

As a result, the amount of powder that melts in the crucible is reduced to 5
It has been found that the oxide single crystal can be easily and continuously pulled down even if the crucible volume is increased correspondingly to a large amount such as g or more, and the present invention has been accomplished.

The reason why such an effect is obtained is probably that the crucible itself is not provided with an outlet for the melt, but the crucible is provided with a nozzle portion and the nosle portion is provided with a single crystal growth portion. By making it difficult for the single crystal growth part to be directly affected by the amount of heat generated by the melt in the crucible, and at the same time controlling the temperature of the single crystal growth part and the crucible separately, the temperature gradient in the vicinity of the single crystal growth part can be improved. It is thought that it was possible to make it larger.

In the conventional form in which the bottom of the crucible is provided with a draw-out port and the melt is directly drawn out from the draw-out port, the draw-out port is caused by the thermal influence of the crucible and the melt therein in the vicinity of the draw-out port. Perhaps it was not possible to form a good solid-liquid interface in the vicinity.

Moreover, according to the present invention, it is not only possible to melt a large amount of powder and continuously withdraw it from the lower end portion of the nozzle portion. The inventor used a conventional single crystal production apparatus, but kept the amount of powder in the crucible to about 300 to 500 mg, and continuously pulled out the KLN single crystal fiber. Then, the composition was measured accurately. As a result, the composition is 1.0 mol
It was discovered that there was a fluctuation of about%.

On the other hand, according to the manufacturing method of the present invention, even if the amount of the raw material powder melted in the crucible is increased to about 30 to 50 g, the compositional variation in the KLN single crystal fiber is small. It was discovered that the accuracy was reduced to a surprising accuracy of 0.01 mol% or less. As described above, according to the manufacturing method and the apparatus of the present invention, surprisingly high accuracy can be realized even from the viewpoint of improving the homogeneity of the composition of the single crystal, as compared with the conventional μ lowering method. did it.

[0016]

Further, the present inventor studied the state of the melt in the single crystal growing portion and the physical properties of the single crystal by using the above-mentioned manufacturing apparatus. As a result, when the surface tension is more dominant than the gravity in the environment of the single crystal growth part, it is possible to continuously extract a good oxide single crystal with extremely small fluctuation in composition. I found it. This is probably because a good solid-liquid phase interface is formed.

As described above, in order to generate the condition that the surface tension is more dominant than the gravity in the single crystal growth portion, it is effective to provide a mechanism for reducing the gravity applied to the melt in the nozzle portion. .

The present inventor has studied such a mechanism. Particularly, by setting the inner diameter of the nozzle portion to 0.5 mm or less, the surface tension is more dominant than the gravity applied to the melt in the nozzle portion. It was confirmed that various conditions can be generated and a uniform meniscus can be formed at the tip opening of the nozzle portion.

However, the inner diameter of this nozzle is 0.01 m.
If it is less than m, the growth rate of the single crystal becomes too small. Therefore, from the viewpoint of mass production, the inner diameter of the nozzle portion is preferably 0.01 mm or more. The optimum inner diameter of the nozzle is
Within the range of 0.01 to 0.5 mm, it slightly varies depending on the viscosity of the melt, the surface tension, the specific gravity, the growth rate of the single crystal, and the like.

Further, as a result of pursuing this point, the present inventor has obtained the following knowledge. That is, in the conventional μ pulling down method, it is considered that the single crystal fiber could be continuously pulled down because the scale of the crucible was small, but this was because the amount of melt in the crucible was small,
Since the melt adhered to the wall surface of the crucible due to its surface tension, the gravity applied to the outlet was relatively small.Therefore, a solid-liquid phase interface was formed to a certain extent. Can be estimated. However, it is presumed that when the size of the crucible was increased, the condition in which the surface tension was dominant near the outlet was lost.

Further, in the present invention, it is easy to increase the temperature gradient when the nozzle portion is viewed in the lengthwise direction near the single crystal growing portion. As a result, the melt flowing down in the nozzle portion can be rapidly cooled.

Therefore, the present invention is particularly suitable for producing a solid solution single crystal. In a solid solution single crystal,
Under equilibrium conditions, the composition ratio has the property of fluctuating. When the conventional μ-down method is used, the composition of the solid solution fluctuates due to a slight temperature change or a change in the solidification rate because the equilibrium condition is present near the outlet, which is considered to be due to such a cause. On the other hand, according to the method and apparatus of the present invention, rapid cooling in the vicinity of the single crystal growth portion is possible, and therefore the composition of the melt can be maintained.

As such a solid solution, for example, KL
N, KLTN [K₃Li _2-2x(Ta_yNb_1-y)_{5 + x}O
_{15 + x}], Ba_1-XSr_XNb₂O₆Tongue
Examples of structure of stainless bronze and Mn-Zn ferrite
Can be

Further, for the above-mentioned reason, it is possible to produce an oxide single crystal having composition segregation. For example, LiNb
When neodymium is dissolved in O ₃ as a solid solution, since the segregation coefficient is not 1, only a smaller amount of neodymium than the amount of neodymium in the composition of the melt enters the single crystal. For example, even if about 1.0 mol of neodymium is contained in the melt, only about 0.3 mol is contained in the single crystal. However, according to the present invention, a single crystal having a composition similar to that of the melt can be produced without causing segregation by rapidly cooling the melt in the nozzle portion as described above. This is YA replaced by other laser single crystals, eg Nd, Er, Yb.
The same can be applied to YVO ₄ substituted with G, Nd, Er, Yb.

As a result of further studies, the present inventor has obtained the following findings. That is, nozzles having various inner diameters were formed of platinum, and a single crystal growth experiment such as KLN was actually performed. As a result, when the amount of the melt in the crucible is large, the melt drips from the tip surface of the nozzle portion, which may make it difficult to grow the fiber or the like. For example, when the height of the liquid surface of the melt (height from the bottom surface of the crucible) is increased to 30 mm or more, and further to 50 mm or more, the inner diameter of the nozzle portion is reduced to 0.2 to 0.5 mm. Also, liquid dripping occurred from the tip surface of the nozzle part.

As described above, in order to stably mass-produce the oxide single crystal even if the amount of raw material accommodated in the crucible is increased, a nozzle portion is provided on the side surface of the crucible, and a part of the nozzle portion is provided. Can be formed so as to extend in the upward direction beyond the connecting portion between the crucible and the nozzle portion. Thus, the difference between the height of the tip surface of the nozzle portion and the height of the liquid surface of the melt is set so that the oxide single crystal can be pulled down most stably.

How to set the difference between the height of the tip surface of the nozzle portion and the height of the liquid surface of the melt to obtain the optimum growth conditions depends on the physical properties of the crystal (viscosity, melting point, etc.), the furnace body, and the like. It is determined by a number of factors such as the structure (temperature distribution, etc.), the crucible structure (the shape of the melting part, the shape of the nozzle part), the growth temperature, the temperature gradient of the single crystal growth part, etc. However, for example, if this difference is increased, the growth rate is increased, and if this difference is decreased, the influence of gravity applied to the melt on the tip end surface of the nozzle portion is further reduced, and liquid dripping is less likely to occur. Therefore, when the height of the tip surface of the nozzle part is 0, the height of the liquid surface of the melt in the crucible is -10 mm or more and 50 mm.
The following is preferable. Here, by setting the height of the liquid surface of the melt to 50 mm or less, the control of the above-mentioned growing state becomes easier. On the other hand, even when the height of the tip surface of the nozzle portion is higher than the height of the liquid surface of the melt in the crucible, if the difference is 10 mm or less, the melt is continuously supplied by the capillary phenomenon in the nozzle portion. To be done. The tip surface of the nozzle portion may be provided at a position lower than the bottom surface of the melt in the crucible.

In this embodiment, a heat insulating wall for heat insulating the melting furnace containing the crucible and the growing furnace having the single crystal growing portion is further provided, and the through hole provided in the heat insulating wall has a through hole. The nozzle part can be inserted. As a result, the melt in the crucible can be melted at a sufficiently high temperature, and the temperature difference between the temperature of the single crystal growth part and the melt in the crucible can be freely controlled, and the melt flowing through the nozzle part can be controlled. Can be cooled rapidly in the single crystal growth part.

In the manufacturing apparatus of the present invention, the crucible heating method is not particularly limited. However, it is preferable to provide a heating furnace so as to surround the single crystal manufacturing apparatus. In the aspect in which the nozzle portion extending downward of the crucible is provided, the heating furnace is separated into an upper furnace and a lower furnace, the crucible is surrounded by the upper furnace, and the upper furnace generates heat at a relatively high temperature. Therefore, it is preferable to assist the melting of the powder in the crucible. On the other hand, a lower furnace is installed around the nozzle, and the temperature of the lower furnace is relatively lowered to increase the temperature gradient in the single crystal growing portion at the lower end of the nozzle. Is preferred.

Further, in order to improve the efficiency of melting the powder in the crucible, rather than heating the crucible only by the heating furnace outside the crucible, the crucible itself is made of a conductive material, and the crucible is supplied with electric power. It is preferable to heat the crucible by supplying Further, in order to maintain the molten state of the molten material flowing in the nozzle portion, it is preferable that the nozzle portion be formed of a conductive material and that the nozzle portion be heated to generate heat.
Alternatively, the temperatures of the nozzle portion and the crucible portion can be controlled by high frequency heating.

In order to increase the temperature gradient particularly in the single crystal growing portion, it is preferable to separate the energizing mechanism of the crucible and the energizing mechanism of the nozzle part so that they can be independently controlled.

As such a conductive material, from the viewpoint of corrosion resistance, materials such as platinum, platinum-gold alloy, platinum-rhodium alloy, platinum-iridium alloy and iridium are preferable.

However, since all corrosion-resistant metals such as platinum have a relatively low resistivity, in order to supply electric power to the metal and effectively generate heat, the thickness of the nozzle portion is reduced. It is necessary to increase the resistance value to some extent or more. For example, when the nozzle portion was formed of platinum, it was necessary to form a thin film having a thickness of about 100 to 200 μm. However, when the nozzle portion is formed of such a thin film, the nozzle portion is structurally weakened and the nozzle portion is deformed, which may make stable production of a single crystal difficult.

Therefore, a resistance heating material is installed so as to surround the nozzle portion, and power can be supplied to the resistance heating material to generate heat. In this case, the nozzle portion may be formed of the corrosion-resistant metal as described above, and current may be supplied to generate heat, but power may not be supplied. In this way, if the resistance heating material that surrounds the nozzle portion is given a major heating function, the heat load required for the nozzle portion is reduced, and it is not necessary to heat the nozzle portion. By making the part thicker (for example, 300 μm or more), the mechanical strength of the nozzle part can be improved, and the device suitable for mass production can be obtained.

Further, according to the manufacturing apparatus of the present invention, the raw material can be continuously or intermittently supplied to the crucible. This is because when a raw material is supplied to the crucible, the heat of fusion of the raw material causes a change in the thermal state in the crucible, which causes a change in the composition of the single crystal and the like. However, according to the present invention, even if such thermal fluctuations occur in the crucible, the thermal effect on the single crystal growth portion is small, and the single crystal growth portion is not in an equilibrium state and is a kinetic state, More and less susceptible to thermal fluctuations.

The present invention can be favorably applied not only to the production of a single crystal fiber, but also to the production of a plate or plate made of a single crystal. A specific plate forming method will be described later.

The KLN single crystal has recently attracted attention as an optical material, and particularly as a single crystal for a blue light second harmonic generation (SHG) element for a semiconductor laser. Since it is possible to generate up to the ultraviolet light region of 390 nm, by using such short wavelength light, it is possible to have a wide range of applications such as optical disk memory, medical, photochemical, and various optical measurement. is there. Further, since the KLN single crystal has a large electro-optical effect, it can be applied to an optical storage element utilizing the photorefractive effect.

Embodiments of the present invention will be described in more detail below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a manufacturing apparatus for growing a single crystal, and FIGS. 2A to 2C are conceptual views for explaining the state of the tip portion of the nozzle portion.

A crucible 7 is installed inside the furnace body. To surround the crucible 7 and its upper space 5,
An upper furnace 1 is installed, and a heater 2 is installed in the upper furnace 1.
Is buried. The nozzle portion 13 extends downward from the lower end portion of the crucible 7, and an opening 13 a is formed in the lower end portion of the nozzle portion 13. The lower furnace 3 is installed so as to surround the nozzle portion 13 and the space 6 around the nozzle portion 13, and the heater 4 is embedded in the lower furnace 3.
Both the crucible 7 and the nozzle portion 13 are made of a corrosion-resistant conductive material. Of course, the form of the heating furnace itself can be variously changed. For example, the heating furnace is divided into two zones in FIG. 1, but the heating furnace can be divided into three or more zones.

To the position A of the crucible 7, one electrode of the power source 10 is connected by the electric wire 9, and to the lower end B of the crucible 7, the other electrode of the power source 10 is connected. One electrode of the power supply 10 is connected to the position C of the nozzle portion 13 by the electric wire 9, and the other electrode is connected to the lower end D of the nozzle portion 13. Each of these energization mechanisms is separated together and is configured so that its voltage can be controlled independently.

Further, after heaters 12 are provided in the space 6 at intervals so as to surround the nozzle portion 13. An intake pipe 11 extends upward in the crucible 7, and an intake port 22 is provided at an upper end of the intake pipe 11. The intake 22 slightly projects from the bottom of the melt 8.

If the temperature gradient in the nozzle portion is optimized by the furnace body (heating element and refractory material), the after-heater 12 is not always necessary.

The melt intake port may be formed at the bottom of the crucible so as not to protrude from the bottom of the crucible. In this case, the intake pipe 11 is not provided. However, if this crucible is used for a long period of time, impurities in the melt may gradually accumulate at the bottom of the crucible. As in the present embodiment, by providing the intake port 22 at the upper end of the intake pipe 11, even if impurities are collected at the bottom of the crucible, the intake pipe 11 projects from the bottom, so that the impurities at the bottom are introduced into the intake port. It is hard to enter.

The upper furnace 1, the lower furnace 3 and the after-heater 12 are caused to generate heat to appropriately determine the temperature distribution of the spaces 5 and 6, and the raw material for the melt is supplied into the crucible 7 to the crucible 7 and the nozzle portion 13. Electricity is supplied to generate heat. In this state, as shown in FIG. 2A, in the single crystal growing portion 35 at the lower end of the nozzle portion 13, the melt 8
Slightly protrudes and is held by the surface tension, so that a relatively flat surface 17 is formed.

The gravity applied to the melt 8 in the nozzle portion 13 is greatly reduced by the contact of the melt with the wall surface in the nozzle portion 13. In particular, by setting the inner diameter of the nozzle portion 13 to 0.5 mm or less, it was possible to form a uniform solid-liquid phase interface as described above.

In this state, seed crystal 15 is moved upward as indicated by arrow E, and end face 15a of seed crystal 15 is brought into contact with surface 17. Next, as shown in FIG. 2B, the seed crystal 15 is pulled down. At this time, a uniform solid-liquid-phase interface (meniscus) 19 is formed between the upper end of the seed crystal 15 and the melt 8 drawn out downward from the nozzle 13.

As a result, as shown in FIG.
The single crystal fiber 14 is continuously formed on the upper side of and is drawn downward. In this embodiment, the seed crystal 15 and the single crystal fiber 14 are sent by a roller 16.

On the other hand, when using the conventional crucible and increasing the amount of powder to be charged into the crucible, the crucible goes downward from the opening 13a of the nozzle portion 13 as shown in FIG. 2 (c). Thus, the expanded portion 20 is formed by the melt 8.
If the end face 15a of the seed crystal 15 is brought into contact with the melt 8 in this state, a good solid-liquid phase interface is not formed.

Since the manufacturing apparatus shown in FIG. 3 is almost the same as the manufacturing apparatus shown in FIG. 1, the same functional members as those in FIG. 1 are designated by the same reference numerals, and the description thereof is incorporated by reference. I will decide. However, in the manufacturing apparatus of FIG. 3, the apparatus of FIG. 1 does not have a mechanism for supplying electric power to the crucible 7 itself, so that the crucible 7 itself is not caused to generate heat. However, even in this case, the raw material in the crucible 7 can be satisfactorily melted by adjusting the temperature of the upper furnace 1 and, if necessary, by installing a high-frequency heating mechanism (not shown) around the crucible 7. You can

FIG. 4 is a schematic sectional view schematically showing a manufacturing apparatus according to still another embodiment. The same parts as those of the apparatus shown in FIGS. The peripheral parts such as the upper furnace and the lower furnace shown in FIGS. 1 and 3 are not shown in FIG. In the apparatus of FIG. 4, the electrode of the power source 10A is connected to the upper end F and the substantially central portion G of the crucible 7, and the power source 10B is connected to the approximately central portion G and the lower end portion H of the crucible 7. The electrodes of the AC power supply 10C are connected to the lower end portion H of the crucible 7 and the upper end portion I of the nozzle portion. The AC power supply 10 is connected to the nozzle unit 13.
Each of these energization mechanisms is separated together and is configured so that its voltage can be controlled independently.

FIG. 5 is a schematic sectional view schematically showing the form of the crucible in the manufacturing apparatus according to still another embodiment.
The nozzle portion 24 extends from the lower end portion of the crucible 7, an opening 24a is formed in the lower end portion of the nozzle portion 24, and the single crystal fiber or the plate 14 is pulled out from the opening 24a. An intake pipe 11 extends upward in the crucible 7, and an intake port 22 is provided at an upper end of the intake pipe 11.

The crucible 7, the intake pipe 11 and the nozzle portion 24 are all made of a corrosion resistant conductive material. For the upper end A and the lower end B of the crucible 7, the power source 1
0 electrodes are connected. A circular tube-shaped heating element 25 is installed so as to surround the periphery of the nozzle portion 24. One electrode of the power supply 10 is connected to the upper end C of the heating element 25 by the electric wire 9, and the other electrode is connected to the lower end D of the heating element 25. Each of these energization mechanisms is separated together and is configured so that its voltage can be controlled independently.

Further, in order to heat the nozzle portion, a high-frequency heating mechanism (not shown) was installed around the nozzle portion, and it was possible to grow the single crystal by precisely controlling this mechanism.

When a DC power source is connected to the nozzle portion 13, bubbles may be generated due to electrolysis of the ionized melt. In this case, it is necessary to connect an AC power source to the nozzle section. However, when the circular tube-shaped heating element 25 is installed around the nozzle portion as in the present embodiment, it is possible to connect a DC power source to the heating element 25.

FIG. 6 is a schematic sectional view schematically showing the crucible 26 used in the manufacturing apparatus of still another embodiment. The nozzle portion 13 extends downward from the lower end of the main body 28 of the crucible 26, and the intake pipe 11A extends upward on the opposite side. Crucible 26
In the main body 28 of the
Is installed between the outer wall of the main body 28 and the intake pipe 11A. The partition wall 27 can be fixed to the outer wall of the main body 28 at a portion not shown, but the partition wall 27 can be attached to a member outside the crucible.

The lower end of the partition wall 27 is not in contact with the bottom 29 of the main body 28, so that a gap 39 is formed between the partition wall 27 and the main body 28. Therefore, when the raw material is supplied from the raw material supply port 37 outside the partition wall 27 to the space 38, the raw material is melted in the space 38, the melt passes through the gap 39 and rises in the space 40, From the intake port 22 enters the intake pipe 11A.

It is generally difficult or expensive to form a nozzle portion having an inner diameter of 0.2 mm or less by processing a material made of a noble metal such as platinum.
Therefore, the present inventor has found that such a fine diameter nozzle having an inner diameter of 0.2 mm or less can be formed by the following method.

That is, a groove is formed in a corrosion-resistant member made of a corrosion-resistant metal or a corrosion-resistant ceramic, preferably a flat plate, and the flat plate is bonded or joined to another corrosion-resistant member, preferably a flat plate, to form a nozzle portion. In the nozzle portion, the groove serves as an elongated fine diameter melt flow hole.

At this time, the grooves are formed on both flat plates,
The melt flow holes can be formed by integrating these grooves when bonding both flat plates. Or, when the groove is formed on one of the flat plates and the other flat plate is left as it is, when bonding both flat plates,
A melt flow hole can be formed by the groove formed on one of the flat plates.

Further, a plurality of rows of grooves are formed in the nozzle portion, each melt flow hole is formed by each groove, and the melt is simultaneously flown out from each melt flow hole, so that the single crystal plate will be described later. Could be formed.

In these cases, the width of each groove is 0.0
It is preferably 1 mm to 0.5 mm, and the interval between the grooves is preferably 0.1 to 10 mm. Moreover, the cross-sectional shape of the groove can be a quadrangle, a V-shape, a semicircle, or the like.

Specifically, as shown in FIG. 7A, an elongated flat plate 41 is prepared, and as shown in FIG. 7B, an elongated groove 42 is formed so as to extend in the longitudinal direction of the flat plate 41. Form. Such a groove 42 is formed on each flat plate 41, as shown in FIG.
As shown in (c), the flat plates 41 are attached to each other to form a nozzle part 43, and the melt flow hole 4 is formed in the nozzle part 43.
4 is formed. As shown in FIG. 7D, the nozzle part 43 is joined to the bottom part 45 a of the crucible 45, and the melt flows down in the melt flow hole 44 of the nozzle part 43. With such a method, a nozzle portion having an inner diameter of 0.2 mm or less for forming a single crystal fiber can be easily manufactured. Of course, the inner diameter of this nozzle portion can be 0.2 mm or more.

Next, a specific form of the nozzle portion for manufacturing the single crystal plate will be described. The inventor
In the μ pull-down method, at the tip of the nozzle part, a flat surface having a planar shape corresponding to the cross section of the single crystal plate is formed, and a plurality of rows of melt flow holes are formed in this nozzle part. At the same time, it was confirmed that a single crystal plate could be formed by pulling down the melt and integrating the melt pulled down from each flow hole along a flat surface.

In this aspect, the entire nozzle portion can be formed into a flat plate shape. In addition, an extension portion may be provided at the tip of the tubular nozzle portion, and the tip end surface of the extension portion may be the flat surface as described above. Alternatively, the nozzle portion may be composed of a plurality of tubular members, the tubular members may be joined together and integrated, and the tip end surface of each tubular member may form an integral flat surface.

For example, as shown in FIG.
In FIG. 6, a plurality of rows of elongated grooves 47 are formed so as to be parallel to each other. As shown in FIG. 8B, the flat plates 46 are attached to each other to form a flat plate-shaped nozzle portion 48, and a plurality of rows of melt flow holes 49 are formed in the nozzle portion 48. Fifty
Is a seam.

As shown in FIG. 8C, the nozzle portion 48 is joined to the bottom of the rectangular crucible 52. The melt in the crucible 52 flows down in the melt flow holes 49 of the nozzle portion 48 and flows out from the melt flow holes 49.
At this time, the melt flowing out from each melt flow hole integrally flows on the flat surface 48a of the nozzle portion 48 and becomes a solid phase immediately below the flat surface 48a. The crystal 53 is pulled out downward of the nozzle portion 48. With such a method, a nozzle portion having a small inner diameter for forming a single crystal plate can be easily manufactured.

Further, in the embodiment shown in FIG. 9, the nozzle portion 71 is formed by a plurality of tubular members 55. The tubular members 55 were arranged in a line, and the outer peripheral surfaces of the tubular members 55 were installed so as to be continuous. However, in FIG.
Although illustration of the crucible portion is omitted, for example, a crucible as shown in FIG. 8C can be used. In each tubular member 55, a melt flow hole 54 is formed,
Each circulation hole 54 is open to the bottom surface 55a at the lower end of each tubular member 55.

The melt in the crucible flows down through the flow holes 54 of the tubular members 55 and flows out from the flow holes 54 to the bottom surface 55a. At this time, the melt flowing out from each of the flow holes 54 integrally flows on the flat surface 72 formed of each bottom surface of the tubular member, and becomes a solid phase immediately below the flat surface 72. As a result, the plate-shaped single crystal 53 is moved to the nozzle portion 71.
Is pulled out toward below.

Further, a diameter-expanded portion can be provided at the tip of the nozzle portion. That is, when the nozzle portion is made of a refractory metal such as platinum, it is preferable that the thickness of the nozzle portion be 0.2 mm or less in order to energize the nozzle portion to generate heat. Also, there is an upper limit on the diameter of the flow hole inside the nozzle portion. Therefore, the outer diameter of the nozzle portion is limited.
On the other hand, the diameter of the fiber pulled down from the nozzle portion is usually less than or equal to the outer diameter of the nozzle portion. As a result, the outer diameter of the nozzle portion may become smaller than the desired outer diameter of the fiber, and in this case, the fiber cannot be pulled down. As a means for solving this problem, the nozzle portion can be composed of a main body having a relatively small outer diameter and an enlarged diameter portion provided at the tip of the main body having a relatively large outer diameter.

FIG. 10 is a schematic cross-sectional view schematically showing an apparatus according to this aspect of the present invention. A nozzle portion 58 extends from the lower end of the crucible 7. The nozzle portion 58 includes a main body 56 of the nozzle portion and a diameter-expanded portion 57 at the lower end portion of the main body 56. The single crystal growth portion 35 is provided in the expanded diameter portion 57. The single crystal fiber 14 is drawn out from the opening 57a of the expanded diameter portion 57 as shown by an arrow J. Crucible 7, intake pipe 11, nozzle body 56, expanded diameter portion 57
Are formed of a corrosion-resistant conductive material. The electrodes of the power source 10 are connected to the upper end A and the lower end B of the crucible 7. Further, the electric wire 9 from the power source 10 is connected to the main body 56 of the nozzle portion at C and D, for example.

Next, an example will be described in which an extension portion is provided at the tip of the tubular nozzle portion, the tip surface of this extension portion is made the above-mentioned flat surface, and the single crystal plate is pulled down along this flat surface. FIG. 11 is a schematic cross-sectional view schematically showing the device according to this aspect. A nozzle portion extends from the lower end portion of the crucible 7. There is a melt flow hole 59a in the main body 59 of the nozzle portion, and an opening 59b is formed at the lower end.

The expansion portion 60 is joined to the bottom of the main body 59. The outer shell 60a of the expansion portion 60 has a substantially flat plate shape,
A flow hole 60c is formed in the outer shell 60a so as to spread horizontally in the drawing. Further, a large number of vertically extending through holes 60b are formed in the outer shell 60a, and the through holes 60b are formed horizontally and at regular intervals. An opening 60d is formed on the tip side of each circulation hole 60b. A flat surface 61 is formed below the expansion portion 60.

The melt in the crucible 7 is the main body 5 of the nozzle part.
9 flows down in the flow hole 59a, flows horizontally through the flow hole 60c, passes through each flow hole 60b, and flows out from the opening 60d. The melt flowing out from each opening 60d is flat surface 61.
It flows integrally as above and becomes a solid phase immediately below this flat surface 61, whereby the plate-shaped single crystal 53 is pulled out toward the lower part of the nozzle portion.

FIG. 12 is a schematic sectional view showing a manufacturing apparatus for growing a single crystal according to still another embodiment of the present invention.
FIG. 13 is a plan view schematically showing the device of FIG. 12. A substantially cylindrical crucible 63 is installed inside the melting furnace 66, and heating devices 65A, 65B, and 65C are installed so as to surround the crucible 63 from, for example, three directions. The melt 8 is contained in the crucible 63. Crucible 6
One of the electrodes of the power source 10 is connected to the position A of 3 by the electric wire 9, and the lower end B of the crucible 63 is
The other electrode of the power supply 10 is connected. Although the bottom wall 63b of the crucible 63 has a flat plate shape in this embodiment, this shape can be variously changed.

Melting furnace 66 in which crucible 63 is installed
Is separated from the growing furnace by a heat insulating wall 68. A nozzle portion 64 is provided on the side wall 63 a of the crucible 63. Both the crucible and the nozzle portion are formed of a corrosion-resistant conductive material. The nozzle portion 64 includes a horizontal portion 64a protruding horizontally from the side wall 63a, a vertical portion 64b extending vertically from the horizontal portion 64a, an insertion portion 64c inserted into the through hole 68a of the heat insulating wall 68,
In addition, a tip portion 64d extending downward from the tip of the insertion portion 64c is provided. That is, the nozzle portion 64 includes the vertical portion 64b extending upward when viewed from the connecting portion 77 of the nozzle portion and the crucible. The power source 10 is connected to a predetermined portion of the nozzle portion 64, for example, L or M, so that the nozzle portion 64 can generate heat.

Here, the projecting position of the nozzle portion 64 from the crucible 63 is preferably provided between the liquid surface 30 of the melt and the bottom surface 73 of the crucible at a height not higher than the middle of both.
This is because, particularly when the raw material is continuously or intermittently supplied into the crucible, a minute variation in the composition is likely to occur near the liquid surface of the melt 8, which affects the composition of the oxide single crystal. There is a possibility that the above-mentioned protruding position of the nozzle portion is provided at a height not higher than the middle of the liquid surface 30 of the melt and the bottom surface 73 of the crucible, thereby preventing the influence on the composition due to the supply of the raw material. Because you can.

The heating devices 65A, 65B and 65C are caused to generate heat, and the crucible is energized to generate heat, whereby the raw material in the crucible is melted. The temperature distribution in the nozzle portion 64 is appropriately determined by energizing the nozzle portion 64 so that the melt does not stay in the nozzle portion 64. With this,
By appropriately setting the thickness and material of the heat insulating wall 68, the temperature of the heater 67, and the temperature of the after-heater 12, the temperature distribution in the vicinity of the single crystal growth portion 35 is optimized in particular. This pulls down the single crystal fiber or plate 14 from the opening 76 in the nozzle portion 64. In this embodiment, the seed crystal 15 and the single crystal fiber 14 are used.
Is sent by the roller 16.

Also in the single crystal manufacturing apparatus as shown in FIGS. 12 and 13, as described above, a flat surface is provided at least at the tip of the nozzle portion, and the single crystal plate is pulled down along this flat surface. You can Also in this case, as described above, it is possible to use the plate-shaped nozzle portion. However, in this aspect, the nozzle portion itself is bent so that the outlet of the nozzle portion is positioned higher than the bottom surface of the crucible. At this time, the plate-shaped nozzle portion may be replaced by, for example, the one shown in
Bending as shown in FIG. 3 can also be implemented in manufacturing.

The form of the nozzle body itself is
For example, a tubular body as shown in FIG. 12 is provided, and an extension portion is provided at the tip of the tubular main body of the tubular portion, and the tip surface of the extension portion is the flat surface as described above, and the single crystal plate is pulled down along the flat surface. be able to. This aspect will be illustrated with reference to FIG.

FIG. 14 is a partial cross-sectional view of the vicinity of the tip of the nozzle portion when another nozzle portion is used in the single crystal manufacturing apparatus shown in FIGS. 12 and 13 as seen from the growth furnace side. is there. The crucible 63 and the melting furnace of the manufacturing apparatus of this embodiment are the same as those shown in FIGS. The main body 69 of the nozzle portion is formed vertically downward on the outside of the through hole 68 a, and the main body 69 has an extension portion 60.
Are joined. There is a through hole 69a in the main body 69, and an opening 69b is formed at the lower end.

The form of the expansion section 60 is the same as that shown in FIG. The melted material in the crucible 7 flows down in the circulation holes of the main body 69 of the nozzle portion, flows horizontally in the circulation holes 60c, passes through the circulation holes 60b, and flows out from the openings 60d.
The melt flowing out from each opening 60d integrally flows on the flat surface 61 and becomes a solid phase immediately below the flat surface 61, whereby the plate-shaped single crystal 53 moves toward the lower side of the nozzle portion. Be withdrawn.

[0082]

[Examples] More specific experimental results will be described below. Example 1 A KLN single crystal fiber was manufactured according to the present invention using a single crystal manufacturing apparatus as shown in FIG. However, as the nozzle portion, the nozzle portion 58 having the form shown in FIG. 10 was used. The temperature inside the furnace was controlled by the upper furnace 1 and the lower furnace 3. The temperature gradient in the vicinity of the single crystal growth part 35 can be controlled by supplying power to the nozzle part 58 and generating heat from the after-heater 12. As a mechanism for pulling down the single crystal fiber, a mechanism for pulling down the single crystal fiber was mounted while controlling the pulling speed uniformly within the range of 2 to 100 mm / hour in the vertical direction.

Potassium carbonate, lithium carbonate and niobium oxide were mixed in a composition ratio of 30:20:50 to produce a raw material powder. About 50 g of the raw material powder was supplied into the crucible 7 made of platinum, and the crucible 7 was set at a predetermined position.
The temperature of the space 5 in the upper furnace 1 was adjusted to a range of 1100 to 1200 ° C. to melt the raw material in the crucible 7. Lower furnace 3
The temperature of the inner space 6 was uniformly controlled at 500 to 1000 ° C. Predetermined electric power was supplied to the crucible 7, the nozzle portion 58, and the after-heater 12 to grow a single crystal. At this time, the temperature of the single crystal growing portion is set to 1050 ° C to 115 ° C.
The temperature could be set to 0 ° C., and the temperature gradient in the single crystal growing portion could be controlled to 10 to 150 ° C./mm.

The outer and inner cross-sectional shapes of the nozzle portion 58 were circular. Of these, the outer diameter of the main body 56 is 0.4
mm, the inner diameter was 0.2 mm, and the length was 20 mm. The outer diameter of the expanded diameter portion 57 is 1.0 mm, and the inner diameter is 0.2
mm and the length was 2 mm. The planar shape of the crucible 7 is circular, its diameter is 30 mm, and its height is 30 m.
m. In this state, when the single crystal fiber was pulled down in the a-axis direction at a speed of 20 mm / hour, a good KL was obtained.
It has been found that the N single crystal fiber can be pulled down. Further, similarly to this, the single crystal fiber could be pulled down also in the c-axis direction.

Further, the thus-grown, 1 mm in length and 1 in width
With respect to a single crystal fiber having a length of 100 mm and a length of 100 mm, the composition distribution was examined when the single crystal fiber was viewed in the length direction (growing direction). Specifically, SHG
The phase matching wavelength was irradiated to each part in the length direction of the single crystal fiber, and the wavelength of the output light was measured. If the composition of the KLN single crystal fluctuates even a slight amount, the composition fluctuation causes a change in the SHG phase matching wavelength.

When this measurement was carried out, the composition could be controlled with an accuracy of 1 nm or less, that is, with an accuracy of 0.01 mol% or less in terms of composition, which is as high as ever as a KLN single crystal. Further, the wavelength conversion efficiency was also the same as the theoretical value within a measurement error range of approximately ± 2% or less.

(Embodiment 2) In the same manner as in Embodiment 1, KL
N single crystal fiber was grown. However, a raw material supply mechanism for intermittently feeding the raw material to the crucible 7 was provided in the furnace.
Further, a single crystal fiber was continuously grown by providing a mechanism for intermittently cutting the single crystal fiber to a predetermined length under the furnace. As the growth of the single crystal fiber progresses, the amount of the grown single crystal and the crucible 7
The raw material powder was supplied into the crucible 7 in an amount corresponding to the amount of the components volatilized from the crucible 7. Thus, a single crystal fiber having a length of about 10 m was continuously formed, and the composition variation was measured by the same method as in Example 1. As a result, the composition variation is 0.01 mol over the entire length of about 10 m.
Succeeded in controlling below%.

(Embodiment 3) Nozzle portion 48 as shown in FIG.
Using the crucible 52, the KLN single crystal plate having a thickness of 1 mm and a width of 30 mm was successfully pulled down. However, the size of the flat plate 46 is 30 mm × 30 mm × 0.
A 6 mm platinum plate was used. Grooves 47 were formed on this platinum plate by dicing. However, the interval between the grooves 47 was 5 mm, and the width of the grooves 47 was 0.1 mm. By joining two platinum plates, a 1.2 mm-thick flat plate-shaped nozzle portion was formed. As described with reference to FIGS. 8A to 8C, the melt was flown from each melt flow hole. When the SHG phase matching wavelength and the conversion efficiency inside the single crystal plate were measured, the same values as in the case of the single crystal fiber described above were obtained.

(Example 4) The present invention was applied to a method for growing a single crystal in which neodymium was solid-solved in LiNbO ₃ . However, in this system, for example, when the CZ method is used, the solid solution amount of neodymium is about 0.3 mol%.

Neodymium oxide, lithium carbonate and niobium oxide were mixed in a molar ratio of 1:49:50 to prepare a raw material powder. The same single crystal fiber manufacturing apparatus as in Example 1 was used. About 50 g of the above raw material powder was placed in the crucible 7. The temperature of the space 5 in the upper furnace 1 was set to 1250
The raw material in the crucible 7 was melted by adjusting the temperature in the range of ˜1350 ° C. The temperature of the space 6 in the lower furnace 3 is 500 to 120.
The temperature was uniformly controlled at 0 ° C. Predetermined electric power was supplied to the crucible 7, the nozzle portion 13 and the after-heater 12 to grow a single crystal.

At this time, the temperature of the single crystal growing portion was set to 1200 ° C.
Up to 1300 ° C. and the temperature gradient in the single crystal growth part is 1
It was controlled at 0 to 150 ° C / mm. 20mm in this state
When pulling down the single crystal fiber at a speed of / hour,
It has been found that a good Nd-LiNbO ₃ single crystal fiber can be pulled down.

Further, thus grown, 1 mm in length and 1 in width
With respect to a single crystal fiber having a length of 100 mm and a length of 100 mm, the element distribution was analyzed by EPMA for the composition distribution when the single crystal fiber was viewed in the length direction (growing direction). As a result, the ratio of neodymium was set to 1.0 mol% in the composition of the raw material powder, but in the single crystal fiber,
It was found that the composition was controlled with an accuracy equal to or lower than the detection limit of ± 2% with respect to 1.0 mol%. Further, when an Nd laser oscillation experiment was performed using this single crystal, an output that was three times or more that of a sample manufactured by the CZ method could be obtained, and its wavelength characteristic was also sharp.

(Embodiment 5) A single crystal production apparatus as shown in FIGS. 12 and 13 was used, and K was used in accordance with the method described above.
LN single crystal fiber was manufactured. Potassium carbonate, lithium carbonate and niobium oxide were mixed in a composition ratio of 30:20:50 to produce a raw material powder. About 5 of this raw material powder
0 g was supplied into a platinum crucible 63, and this crucible was set at a predetermined position. Heating device 65A, 65B, 65C
The temperature in the melting furnace 66 was controlled by, and the temperature on the growth furnace 70 side was controlled by the heating device 67. The temperature gradient in the vicinity of the single crystal growth portion 35 can be controlled by supplying power to the nozzle portion 64 and heat generation from the after heater 12. As the pulling mechanism of the single crystal fiber,
A mechanism for pulling down the single crystal fiber was mounted while uniformly controlling the pulling rate within the range of 2 to 100 mm / hour in the vertical direction.

The inside of the melting furnace was controlled at 1100 ° C. to 1200 ° C. to melt the raw material in the crucible. The temperature of the growth furnace 70 was uniformly controlled at 500 to 1000 ° C. Crucible 6
3, a predetermined electric power was supplied to the nozzle portion 64 and the after-heater 12, the temperature gradient in each portion was optimized, and a single crystal was grown. At this time, the single crystal growth unit 3
The temperature of No. 5 was set to 1050 ° C to 1150 ° C, and the temperature gradient in the single crystal growing portion could be controlled to 10 to 150 ° C / mm.

Both the outer shape and the inner shape of the cross section of the nozzle portion 64 are circular, the outer diameter is 1 mm, and the inner diameter is 0.8 m.
m and the length was about 50 mm. The nozzle portion 64 was pulled out horizontally from the vicinity of the middle of the liquid surface 30 and the bottom surface 73 of the melt of the crucible 63. The crucible 63 had a circular plan shape, a diameter of 30 mm, and a height of 30 mm. In this state, when the single crystal fiber was pulled down in the a-axis direction at a speed of 20 mm / hour, it was found that a good KLN single crystal fiber could be pulled down. Also,
In the same manner, the single crystal fiber could be pulled down in the c-axis direction.

Further, thus grown, 1 mm in length and 1 in width
With respect to a single crystal fiber having a size of 100 mm and a length of 100 mm, the composition distribution when the single crystal fiber was viewed in the length direction (growing direction) was tested in the same manner as in Example 1. As a result, the composition could be controlled with an accuracy of 1 nm or less, that is, with a high accuracy of 0.01 mol% or less when converted to the composition, which is unprecedented as a KLN single crystal. Further, the wavelength conversion efficiency was also the same as the theoretical value within a measurement error range of approximately ± 2% or less.

(Sixth Embodiment) KL is carried out in the same manner as in the fifth embodiment.
N single crystal fiber was grown. However, a raw material supply mechanism for intermittently feeding the raw material to the crucible 63 was provided in the furnace. Moreover, a single crystal fiber was continuously grown by providing a mechanism under the afterheater to intermittently cut the single crystal fiber into a predetermined length.

As the growth of the single crystal fiber progresses, the amount of melt in the crucible decreases. Here, the liquid level of the melt is 0.5 mm with respect to the tip of the nozzle part.
The raw material powder was supplied into the crucible so that it was located at a position higher by about ± 0.1 mm. In this way, a single crystal fiber with a length of about 10 m is continuously formed, and the composition variation is
The measurement was performed in the same manner as in Example 1. As a result, about 10
The composition variation is 0.01 m over the entire length of m.
Succeeded in suppressing to less than ol%.

Example 7 A single crystal was grown in the same manner as in Example 5, and a nozzle portion as shown in FIG. 14 was used to pull down a KLN single crystal plate having a thickness of 1 mm and a width of 30 mm. Successful. The tip 60 is 3m high
It was formed by a platinum plate having m, a width of 30 mm and a thickness of 1 mm. The distance between the flow holes 60b is 3 mm, and the flow holes 60 are
Each width of b was 0.5 mm.

As the growth of the single crystal plate progresses, the amount of melt in the crucible decreases. Here, the liquid level of the melt is 2.0 ± with respect to the tip of the nozzle.
The raw material powder was fed into the crucible so that the raw material powder was located at a position higher by about 0.1 mm. SH inside the single crystal plate
When the G phase matching wavelength and the conversion efficiency were measured, the same values as in the case of the single crystal fiber described above were obtained.

(Example 8) The present invention was applied to a method for growing a single crystal in which neodymium was dissolved in LiNbO ₃ as a solid solution. This single crystal was grown in the same manner as in Example 5. However, neodymium oxide, lithium carbonate, and niobium oxide were mixed in a molar ratio of 1:49:50 to prepare a raw material powder. Approximately 50 g of raw material powder is added to a platinum crucible 63
Housed inside. The inside of the melting furnace is 1250 ° C-1350 ° C.
The raw material in the crucible was melted under the control. The temperature of the growth furnace 70 was uniformly controlled at 500 to 1200 ° C. Predetermined electric power was supplied to the crucible 63, the nozzle portion 64, and the after-heater 12 to optimize the temperature gradient in each portion and grow a single crystal. At this time, the temperature of the single crystal growing portion 35 was set to 1200 ° C to 1300 ° C, and the temperature gradient in the single crystal growing portion was controlled to 10 to 50 ° C / mm.

In this state, when the single crystal fiber was pulled down at a speed of 20 mm / hour, it was found that a good single crystal fiber could be pulled down.

[0103] Furthermore, the thus-grown, vertical 1 mm, horizontal 1
With respect to a single crystal fiber having a length of 100 mm and a length of 100 mm, the element distribution was analyzed by EPMA for the composition distribution when the single crystal fiber was viewed in the length direction (growing direction). As a result, the ratio of neodymium was set to 1.0 mol% in the composition of the raw material powder, but in the single crystal fiber,
It was found that the composition was controlled with an accuracy equal to or lower than the detection limit of ± 2% with respect to 1.0 mol%. Further, when an Nd laser oscillation experiment was performed using this single crystal, an output that was three times or more that of a sample manufactured by the CZ method could be obtained, and its wavelength characteristic was also sharp.

(Comparative Experiment 1) A KLN single crystal fiber similar to that of Experiment 1 was prepared by using a manufacturing apparatus having a conventional structure. The amount of raw material powder was 500 mg. The crucible was made of platinum. The temperature inside the furnace was controlled by the upper furnace and the lower furnace. Set the temperature of the space in the upper furnace to 1100-1
The raw material in the crucible was melted by adjusting the temperature within the range of 200 ° C. The temperature of the space 6 in the lower furnace 3 is 500 to 1000 ° C.
Controlled uniformly. An electric power was supplied to the crucible, and an attempt was made to control the growth and the pulling out of the single crystal from the pulling opening by this. In this state, when the single crystal fiber was pulled down at a speed of 20 mm / hour, the KLN single crystal fiber could be pulled down.

[0105] Thus manufactured, 1 mm long, 1 mm wide,
With respect to a single crystal fiber having a length of 100 mm, the composition distribution when the single crystal fiber was viewed in the length direction (growing direction) was examined in the same manner as in Experiment 1. As a result, the wavelength of the output light changed by 50 nm. This exceeds 1.0 mol% in terms of composition, and S
For HG devices, there was a problem in practical use.

(Comparative Experiment 2) In Comparative Experiment 1, raw material powders in an amount corresponding to the amounts of the component extracted from the crucible and the component evaporated from the crucible were periodically supplied to the crucible to continuously produce a single crystal. Tried to grow fibers. However, once the raw material was supplied, the thermal equilibrium state in the crucible was greatly disrupted, making it impossible to continue growing the single crystal fiber.

(Comparative Experiment 3) In Comparative Experiment 1, the size of the crucible was increased and the amount of raw material powder initially charged into the crucible was increased to 5 g. An attempt was made to control the temperature in the entire furnace by the upper furnace and the lower furnace and supply electric power to the crucible, thereby controlling the growth and extraction of the single crystal from the extraction port.

However, the temperature in the upper furnace is set to 500 to 900.
If the temperature is adjusted to a low value of ℃, it is necessary to increase the power supply to the crucible to accelerate the melting of the raw material powder in the crucible. However, when the output was increased, the melt did not crystallize. On the other hand, when the power supplied to the crucible was reduced, the melt solidified before it came out of the outlet. Thus, it was not possible to find the conditions for pulling out the single crystal.

On the other hand, when the temperature of the upper furnace is 900 ° C. or higher, the heat radiation from the furnace body makes it impossible to maintain the temperature gradient necessary for crystallization in the vicinity of the drawing port, which is the crystal growth point. The single crystal fiber could not be pulled down.

[0110]

As described above, according to the present invention, μ
When growing an oxide single crystal by the pull-down method,
It is possible to process a large amount of raw materials and continuously pull down a large amount of oxide single crystals to form, and to prevent fluctuations in the composition of these oxide single crystals, etc. to produce high quality oxide single crystals. can do. Therefore, the present invention is a very important technique in mass-producing such oxide single crystal fibers and plates.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing apparatus for growing a single crystal according to an embodiment of the present invention.

2 (a) to 2 (c) are conceptual diagrams for explaining a state of a tip portion of a nozzle portion 13 of a manufacturing apparatus for growing a single crystal.

FIG. 3 is a schematic sectional view showing a manufacturing apparatus for growing a single crystal according to another embodiment of the present invention.

FIG. 4 shows a manufacturing apparatus according to still another embodiment of the present invention,
It is a schematic sectional drawing which shows the structure of a crucible and its electric power supply mechanism roughly.

FIG. 5 shows a manufacturing apparatus according to still another embodiment of the present invention,
It is a schematic sectional drawing which shows the structure of a crucible and its electric power supply mechanism roughly.

FIG. 6 shows a manufacturing apparatus according to still another embodiment of the present invention,
It is a schematic sectional drawing which shows the structure of a crucible schematically.

7A is a plan view showing a flat plate 41 made of a corrosion resistant material, FIG. 7B is a plan view showing a state in which a groove 42 is formed in the flat plate 41, and FIG. Flat plate 4
It is sectional drawing which shows the nozzle part 43 formed by joining 1 and (d) is sectional drawing which shows the crucible 45 to which this nozzle part 43 was attached.

FIG. 8A is a plan view showing a state in which a plurality of rows of grooves 47 are formed in a flat plate 46 made of a corrosion-resistant material, and FIG.
Is a sectional view showing a nozzle portion 48 formed by joining a pair of flat plates 46, and (c) is a sectional view showing a crucible 45 to which the nozzle portion 48 is attached.

FIG. 9 is a cutaway perspective view showing a nozzle portion 71 including a plurality of tubular members 55.

FIG. 10 is a cross-sectional view schematically showing the periphery of a crucible and a nozzle portion 58 in which an enlarged diameter portion 57 having a relatively large diameter is provided at the tip of a nozzle portion main body 56.

FIG. 11 is a schematic cross-sectional view schematically showing an apparatus according to an aspect in which an extension having a large number of through holes is provided at the tip of the nozzle portion.

FIG. 12 is a schematic sectional view showing a manufacturing apparatus for growing a single crystal according to still another aspect of the present invention.

13 is a plan view schematically showing the device of FIG.

FIG. 14 is a portion of the single crystal manufacturing apparatus shown in FIGS. 12 and 13 when the periphery of the tip of the nozzle portion when another nozzle portion is used is viewed from a direction parallel to the through hole 68a. FIG.

[Explanation of symbols]

1 upper furnace, 2, heater in furnace 4, 3 lower furnace, 5 space in upper furnace 1, 6 space in lower furnace 3,
7,26,45,52,63 crucible, 8 melt,
10 AC power supply (energization mechanism), 11 intake pipe,
12 after heater, 13, 24, 43, 48,
58,64 nozzle part, 14 single crystal fiber or plate, 15 seed crystal, 16 roller, 1
9 Interface between solid phase and liquid phase, 22 Melt intake, 30 Melt surface, 35 Single crystal growth part,
53 single crystal plate, 56 main body of nozzle part 58,
57 expanded diameter part of nozzle part 58, 59 main part of nozzle part, 60 expanded part, 65A, 65B, 65C, 67
Heating device, 48a, 61, 72 flat surface, 66 melting furnace, 68 heat insulating wall, 68a through hole of heat insulating wall 68,
70 growth furnace, 73 bottom of crucible, 75 tip of nozzle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C30B 29/60 7202-4G C30B 29/60

Claims (19)

[Claims] 1. A raw material for an oxide single crystal is melted in a crucible, a seed crystal is brought into contact with the melt, and the oxide single crystal is grown while pulling the melt downward. A method for manufacturing an oxide single crystal, comprising the crucible and a nozzle portion extending from the crucible, and a manufacturing apparatus provided with a single crystal growth portion facing downward at the tip of the nozzle portion. A method for producing an oxide single crystal, which is characterized in that the temperature of the crucible and the single crystal growing portion are controlled independently of each other. 2. The method for producing an oxide single crystal according to claim 1, wherein the surface tension is more dominant than the gravity with respect to the environment of the melt in the single crystal growing portion. . 3. The nozzle portion extends downward from the crucible, and the single crystal growth portion is provided at a lower end portion of the nozzle portion.
Or the method for producing an oxide single crystal according to 2. 4. The nozzle portion is provided on a side surface of the crucible, and a part of the nozzle portion extends upward from a connecting portion between the crucible and the nozzle portion. The method for producing an oxide single crystal according to claim 1 or 2. 5. The height of the liquid surface of the melt in the crucible when the height of the tip surface of the nozzle portion is 0, is −10.
The method for producing an oxide single crystal according to claim 4, wherein the thickness is not less than 50 mm and not more than 50 mm. 6. The oxide single crystal is continuously grown by supplying the raw material to the crucible regularly or continuously while continuously pulling down the melt from the nozzle portion. The method for producing an oxide single crystal according to any one of claims 1 to 5, characterized by: 7. A flat surface having a planar shape corresponding to the cross section of the single crystal plate is formed at the tip of the nozzle part, and a plurality of rows of melt flow holes are formed in this nozzle part. 7. The single crystal plate is formed by simultaneously pulling down the melt from the above, and integrating the melt pulled down from each flow hole along the flat surface. A method for producing an oxide single crystal according to one of the claims. 8. The method for producing an oxide single crystal according to any one of claims 1 to 7, wherein the oxide single crystal is a solid solution single crystal. 9. The method for producing an oxide single crystal according to any one of claims 1 to 7, wherein the oxide single crystal is an oxide single crystal having segregation. 10. A raw material for an oxide single crystal is melted in a crucible, a seed crystal is brought into contact with the melt, and the oxide single crystal is grown while pulling the melt downward. An oxide single crystal manufacturing apparatus, the crucible, a nozzle portion extending from the crucible, a single crystal growth portion provided at the lower end of the nozzle portion, the crucible and the single crystal growth portion to each other. An apparatus for producing an oxide single crystal, comprising a heating mechanism for independently controlling the temperature. 11. The nozzle portion is provided on a side surface of the crucible, and a part of the nozzle portion extends upward from a connecting portion between the crucible and the nozzle portion. The oxide single crystal manufacturing apparatus according to claim 10. 12. A melting furnace containing the crucible,
12. A heat insulating wall for thermally insulating the single crystal growing portion from a growing furnace is provided, and the nozzle portion is inserted into a through hole provided in the heat insulating wall. An apparatus for producing an oxide single crystal as described. 13. The apparatus for producing an oxide single crystal according to claim 10, wherein an inner diameter of the nozzle portion is 0.5 mm or less. 14. The crucible and the nozzle portion are formed of a conductive material, and an electric power supply mechanism for heating the crucible by supplying electric power to the crucible and electric power to the nozzle portion. And a current-carrying mechanism that heats this nozzle section by
13. The apparatus for producing an oxide single crystal according to claim 10, wherein an energization mechanism of the crucible and an energization mechanism of the nozzle unit are separated. 15. The apparatus for producing an oxide single crystal according to claim 14, further comprising an AC power source as an energizing mechanism for the nozzle portion. 16. The apparatus for producing an oxide single crystal according to claim 14, further comprising a high frequency heating mechanism for heating the nozzle portion by high frequency induction. 17. A crucible is formed of a conductive material, a resistance heating material is installed so as to surround the nozzle portion, and a power supply mechanism for generating heat by supplying electric power to the crucible is provided. And an energization mechanism that heats the resistance heating material by supplying electric power to the resistance heating material, and the energization mechanism of the crucible and the energization mechanism of the resistance heating material are separated. The apparatus for producing an oxide single crystal according to any one of claims 10 to 13, which is characterized. 18. The nozzle portion is formed of a joined body of a pair of corrosion resistant members, and a groove is formed on the surface of at least one of the corrosion resistant members, and the groove forms a flow hole for the melt. It is characterized by the above-mentioned.
The apparatus for producing an oxide single crystal according to claim 13. 19. A flat surface having a planar shape corresponding to a cross section of the single crystal plate is formed at the tip of the nozzle portion, and a plurality of rows of melt flow holes are formed in the nozzle portion. The apparatus for producing an oxide single crystal according to any one of claims 10 to 13, characterized in that each opening of the melt flow hole faces the flat surface.