JP3106182B2 - Manufacturing method of bulk single crystal - 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 an oxide bulk single crystal. More specifically, low-temperature phase Ba (B ₁ -xM _x ) ₂ O ₄ (where M ≦ Al, Ga is 0 ≦ x <0.15), which is useful in the optical field such as a laser element and a wavelength conversion element. And a method for efficiently producing an oxide bulk single crystal.

[0002]

2. Description of the Related Art As a conventional industrial bulk single crystal manufacturing method, a pulling method or a floating zone melting method for manufacturing from a melt is known. Bulk single crystals of about -50 mm have been produced. Further, as a method for producing a fiber single crystal having a diameter on the order of microns, a micro pulling method, a micro pulling method, a laser heating pulling method, and the like have been adopted.

However, none of the conventional methods described above has provided a method for efficiently producing a single crystal having a diameter of about 1-2 mm. Diameter 1
In the case of a single crystal of about -2 mm,
It has the feature that it can be used for optical devices only by cutting and polishing both ends. Therefore, the development of an efficient manufacturing method of such a single crystal is desired. There is a problem that some technologies cannot cope.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and has a diameter of 1-2 mm.
To provide a method for producing a bulk single crystal of about using an infrared heating floating zone melting device and a raw material supply tube,
Since a single crystal is produced under a large temperature gradient, a low-temperature phase single crystal is produced efficiently and reproducibly as a high quality single crystal.

[0005] That is, the invention of this application is to solve the above-mentioned problems, by mounting a raw material-filled metal tube filled with a raw material melt and solidified inside thereof to an infrared heating floating zone melting apparatus, The present invention provides a bulk single crystal manufacturing method (claim 1), characterized in that a raw material in a tube is melted and pulled down to generate a single crystal from a melt separated from the tube.

[0006] The invention of this application also specifically provides the following aspects. An elliptical mirror heater is mounted (claim 2). A pair of ring-type mirror heaters are arranged in a vertical direction surrounding the tube (claim 3). The uniform heating length in the tube is controlled by changing the distance between the ring type mirror heaters (claim 4). The temperature gradient in the vertical axis direction during the production of the single crystal is controlled by changing the position of the tube in the infrared heating floating zone melting apparatus (claim 5). The tube is provided with an open taper at the bottom (claim 6). The tube is provided with one or more longitudinal slits on the side surface (claim 7). The tube has a roughened lower side surface to which light is applied (claim 8). The tube is made of a Group VIII noble metal, in particular, the tube is made of platinum. A Group VIII noble metal wire having a mirror-finished tip is used as a substitute for a seed crystal. In particular, the noble metal wire is made of platinum (claims 11 and 12). During the production of a single crystal, the tube is moved downward to apply a compressive force to the solid-liquid interface,
The interface is stabilized (claim 13). The raw material melt is filled into the tube by capillary action and solidified.
4).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the above-mentioned features, but is based on 1) filling a tube with a raw material melt and solidifying it inside; Attach the filled tube to the infrared heating floating zone melting device, 3) melt the raw material in the tube by infrared heating, 4) grow a single crystal from the melt. This method enables a single crystal to be produced with a large temperature gradient, and enables a bulk single crystal having a diameter of about 1 to 2 mm, which has been difficult to produce by a conventional method, to be of high quality, with good reproducibility, and efficiently. It is possible to manufacture.

As a more specific example, as shown in FIG. 1, for example, a single crystal is manufactured by using a halogen lamp or the like to constitute a heat source and an elliptical mirror heater. An elliptical mirror lamp of a single ellipse, a multi-ellipse, or a four-ellipse is used, and a Pt (platinum) tube filled with raw materials and a Pt (platinum) wire as a substitute for a seed crystal are used. Also,
For example, as illustrated in FIG. 2, a pair of ring mirror heaters is formed, and the ring heater surrounds a tube and arranges the heaters vertically.

[0009] For example, the above-described specific forms are exemplified. In any of the above cases, the raw material is heated and melted through a tube, and is reduced to a single crystal. In the infrared heating floating zone melting device having an elliptical mirror heater as described above, the raw material inserted in the tube is melted to uniformly melt the raw material and to keep the raw material supply amount constant during the crystallization of the melt. I try to keep it.

Further, by using an infrared heating floating zone melting device having a pair of ring-type mirror heaters, a heat equalizing portion in the tube is further lengthened compared to an infrared heating floating zone melting device having an elliptical mirror heater, Increase the total raw material supply. Further, it is possible to suppress the difficulty in supplying the raw material due to the solidification of the melt at the top of the raw material tube. At this time, by adjusting the distance between the ring-type mirror heaters and controlling the soaking length as the amount of the feed material decreases, the production conditions of the single crystal can be stably controlled.

According to the present invention, a large temperature gradient can be set in the vertical axis direction because the infrared heating floating zone melting apparatus is used, and the relative position between the tube, the single crystal growth interface, and the temperature center is determined. By changing, the temperature gradient can be set arbitrarily. Further, since the apparatus is an infrared heating floating zone melting apparatus, it is easy to observe a single crystal manufacturing process.

Although the tube is an essential requirement of the present invention, a heat-resistant metal, for example, a Group VIII noble metal, more preferably the above-mentioned Pt can be used. With respect to this tube, for example, the diameter of the single crystal to be manufactured can be adjusted by giving a taper that opens from the upper part to the lower part with respect to the inner diameter. Further, since the light condensing state varies depending on the tube diameter, even when a single crystal having the same diameter is produced, it is possible to produce a single crystal having a different temperature gradient.

By providing a slit in the longitudinal direction on the side surface of the tube, a decrease in the amount of the raw material melt can be easily confirmed. Further, by making the outer surface of the lower part of the tube that is irradiated with light rough, the reflection of light can be suppressed, only the temperature of the tube can be increased, and the temperature gradient in the vertical axis direction increases.

Along with this tube, a noble metal wire whose tip is melted and made into a mirror surface state, particularly preferably a Pt wire is used as a substitute for a seed crystal, so that the wettability between the raw material melt and the Pt wire is improved. , And the amount of light reflected from the front end increases, so that the temperature gradient in the vertical axis direction increases.

During the production of a single crystal, the tube is moved downward, the solid-liquid interface can be stably maintained by the compressive force applied to the interface, and the single crystal can be easily produced. The feed material can be easily produced by filling the tube with the material melt utilizing the capillary phenomenon. In addition, this makes it possible to obtain a raw material tube in which crystals do not adhere to the outside of the tube.

Of course, in the method of the present invention, the type and composition of the bulk single crystal are not limited. For example heretofore difficult production of bulk single crystal of 1 to 2 mm, moreover, laser devices, etc. useful wavelength conversion element, a low temperature phase _{Ba (B 1-X M X} ) 2 O 4 (M is Al or Ga, 0 ≦ x <0.15).

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0018]

EXAMPLE 1 In a muffle type resistance heating electric furnace, 10 g of Ba (B
_0.95 Al _0.05 ) ₂ O ₄ in air, both diameter and height are 3
Melting using a 0 mm Pt crucible (melting point: 1075 ° C)
did. At this time, a Pt tube having a diameter of 4 mm and a length of 50 mm was immersed in the melt, and the melt was introduced into the tube and crystallized. The crystal length in the Pt tube was 20 mm, and the crystal weight was 2 g. Using this as a feed material, a single crystal was manufactured using an infrared heating floating zone melting apparatus having a bi-elliptical mirror heater.

The Pt tube containing the feed material was fixed and suspended above the Al ₂ O ₃ tube from above. From below, a 1 mm diameter Pt wire was inserted in place of the seed crystal. It becomes the mode of FIG. After melting the raw material by raising the temperature, a Pt wire was brought into contact with the melt. The position of the Pt tube and the Pt line was moved up and down while visually confirming a position that was well compatible with the melt, and a position where an optimal temperature gradient for producing a single crystal was obtained. Fix the Pt tube in that position,
The t-line was moved downward at a speed of 10 mm / h. As it moved, a single crystal formed before the Pt line. Two hours later, a single crystal having a diameter of 2 mm and a length of 20 mm was produced at the straight body.

When the manufactured single crystal was irradiated with a Ti: Al ₂ O ₃ laser having a wavelength of 785 nm at room temperature (25 ° C.), a nonlinear optical effect of generating a harmonic having a wavelength of 392 nm was obtained as shown in FIG. The formation of a low-temperature phase was confirmed. Even when the Pt tube and the Pt wire were rotated, a single crystal could be similarly produced.

Also, a single crystal having a diameter of 2 mm could be manufactured by using a Pt tube having a diameter of 2 mm and a tapered diameter of 4 mm and opened at the tip. Example 2 In an induction heating type lifting apparatus, 70 g of Ba (B
_0.9 Al _0.1 ) ₂ O ₄ in air at both diameter and height of 4
Melting using a 0 mm Pt crucible (melting point: 1050 ° C.)
did. At this time, a Pt tube having a diameter of 4 mm and a length of 70 mm was immersed in the melt, the melt was introduced into the Pt tube, and a single crystal having a diameter of 10 mm and a length of 40 mm was produced by a pulling method over 10 hours. Thereafter, the single crystal was cut off from the tube. Crystal length in tube is 30mm
And the crystal weight was 3 g.

Using this Pt tube as a feed material,
Single crystal production was carried out by an infrared heating floating zone melting device having a ring-type mirror heater of the type. The Pt tube containing the feed material was fixed and suspended above the Al ₂ O ₃ tube from above. From below, a 1 mm diameter Pt wire was inserted in place of the seed crystal. FIG. 2 shows an embodiment. After melting the raw material by raising the temperature, a Pt wire was brought into contact with the melt. At this time, when the distance between the ring type mirror heaters was adjusted, all the raw materials were melted at 10 mm. The position of the Pt tube and the Pt line was moved up and down while visually confirming the position where the melt was well compatible, and a position where an optimal temperature gradient for producing a single crystal was obtained was searched. The Pt tube was fixed at that position, and the Pt wire was moved downward at a speed of 10 mm / h. As it moved, a single crystal formed before the Pt line. The distance between the ring-type mirror hitters is 2.5 mm / h
Reduced by. After 4 hours, the straight body part has a diameter of 2 mm and a length of 4
A single crystal of 0 mm was produced.

Compared to Example 1, the floating zone melting apparatus having two sets of ring-type mirror heaters had a longer soaking part, so that a long single crystal could be produced. A Ti: Al ₂ O having a wavelength of 785 nm at room temperature (25 ° C.)
_When irradiated with ₃ lasers, as shown in FIG.
A nonlinear optical effect in which a harmonic of 92 nm occurs is obtained,
The formation of a low-temperature phase was confirmed.

Further, a single crystal can be produced even by using a tube having a slit with a width of 1 mm on the side surface, and the end of the production of the single crystal can be easily determined because the remaining amount of the raw material melt can be known. Was. Example 3 In a muffle type resistance heating electric furnace, 10 g of Ba (B
_0.95 Al _0.05 ) ₂ O ₄ in air, both diameter and height are 3
Melting using a 0 mm Pt crucible (melting point: 1075 ° C)
did. At this time, the Pt tube lower end length of 30 mm is
A Pt tube having a diameter of 4 mm and a length of 50 mm whose surface was roughened by polishing with 600 end water abrasive paper was immersed in the melt, and the melt was introduced into the tube and crystallized. The crystal length in the Pt tube was 20 mm, and the crystal weight was 2 g. Using this as a feed material, a single crystal was manufactured using an infrared heating floating zone melting apparatus having a bi-elliptical mirror heater.

As in the first embodiment, as shown in FIG. 1, the Pt tube containing the feed material is made of Al ₂ O ₃
It was fixed and hung at the end of the tube. A Pt wire having an outer diameter of 1 mm and having a spherical shape with a diameter of 1.5 mm at the upper end was inserted from below, instead of the seed crystal. After melting the raw material by raising the temperature, a Pt wire was brought into contact with the melt. The position of the Pt tube and the Pt line was moved up and down while visually confirming the position where the melt was well compatible, and a position where an optimal temperature gradient for producing a single crystal was obtained was searched. Fix the Pt tube in that position,
The Pt line was moved downward at a speed of 15 mm / h. As it moved, a single crystal formed before the Pt line. Two hours later, a single crystal having a diameter of 2 mm and a length of 30 mm was produced at the straight body.

Compared with the first embodiment, the Pt tube has a rougher surface at the lower end and a Pt wire having a spherical end at the tip.
Even when the moving speed of the wire was high, a single crystal could be produced, and the production of the single crystal was easier than in Example 1. At the room temperature (25 ° C.), a wavelength of 785 n
m Ti: Al ₂ O ₃ laser irradiation, Figure 3
The nonlinear optical effect of generating a harmonic having a wavelength of 392 nm similar to that shown in (1) was obtained, and the generation of a low-temperature phase was confirmed.

Example 4 In a muffle type resistance heating electric furnace, 10 g of Ba (B
_0.95 Al _0.05 ) ₂ O ₄ in air, both diameter and height are 3
Melting using a 0 mm Pt crucible (melting point: 1075 ° C)
did. At this time, a Pt tube having a diameter of 4 mm and a length of 50 mm was immersed in the melt, and the melt was introduced into the Pt tube for crystallization. The crystal length in the Pt tube was 20 mm, and the crystal weight was 2 g. Using this as a feed material, a single crystal was manufactured using an infrared heating floating zone melting apparatus having a bi-elliptical mirror heater.

As shown in FIG. 1, the Pt tube containing the feed material was Al ₂ O ₃
It was fixed and hung at the end of the tube. From below, P with a diameter of 1 mm
A t-line was inserted instead of the seed crystal. After melting the raw material by raising the temperature, a Pt wire was brought into contact with the melt. Pt tube, P
The position of the t-line was moved up and down to find a position where a temperature gradient optimal for single crystal production was obtained. The Pt tube was fixed at that position, and the Pt wire was moved downward at a speed of 10 mm / h. After 15 minutes, the Pt tube was
It was moved downward at a speed of m / h. As it moved, a single crystal formed before the Pt line. 2 hours later, 2m in diameter at the straight body
m, a single crystal having a length of 15 mm was produced.

As compared with Example 1, a single crystal having less variation in outer diameter was produced. Room temperature (25 ° C)
When a Ti: Al ₂ O ₃ laser having a wavelength of 785 nm was irradiated with the above, a nonlinear optical effect of generating a harmonic having a wavelength of 392 nm similar to that shown in FIG. 3 was obtained, and generation of a low-temperature phase was confirmed.

[0030]

As described in detail above, the present invention has the following effects. 1) Since a vertical tube is used and the whole amount is melted, a sufficient stirring effect is obtained and the homogeneity of the melt is excellent. In addition, since the metal tube serves as a heat reservoir, the heat uniformity is good, and the diameter of the single crystal that can be manufactured with the tube diameter and the taper diameter can be controlled.

2) The production speed is high because of the method for producing a single crystal having a diameter of about 1-2 mm. In addition, in the present invention, the tube containing the used raw material used in the pulling method using the tube as a seed can be used as it is to produce a single crystal, so that the raw material adjustment cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a method for producing a single crystal using an infrared (halogen lamp) heating floating zone melting apparatus having a bi-elliptical mirror heater.

FIG. 2 is a schematic diagram showing a method for producing a single crystal using an infrared (halogen lamp) heating floating zone melting apparatus having a pair of ring-type mirror heaters.

[FIG. 3] A Ti: Al ₂ O having a wavelength of 785 nm at room temperature (25 ° C.) is applied to a manufactured Ba (B _0.95 Al _0.05 ) ₂ O ₄ single crystal.
FIG. 3 is a diagram showing the intensity of harmonics generated when irradiating _three lasers.

FIG. 4 shows a Ti: Al ₂ O having a wavelength of 785 nm at room temperature (25 ° C.) on a manufactured Ba (B _0.9 Al _0.1 ) ₂ O ₄ single crystal.
FIG. 3 is a diagram showing the intensity of harmonics generated when irradiating _three lasers.

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Claims (14)

(57) [Claims] 1. A raw material-filled metal tube filled with a raw material melt and solidified therein is mounted on an infrared heating floating zone melting apparatus, the raw material in the tube is melted by infrared heating, pulled down, and separated from the tube. A method for producing a bulk single crystal, comprising forming a single crystal from a melt obtained. 2. The method according to claim 1, wherein an elliptical mirror heater is mounted. 3. The method according to claim 1, wherein a pair of ring-type mirror heaters are arranged in a vertical direction surrounding the tube. 4. A uniform heating length in a tube is controlled by changing a distance between ring-type mirror heaters.
Manufacturing method. 5. The manufacturing method according to claim 1, wherein the temperature gradient in the vertical axis direction during single crystal production is controlled by changing the position of the tube in the infrared heating floating zone melting apparatus. 6. The method according to claim 1, wherein the tube is provided with an open taper at a lower portion. 7. The method according to claim 1, wherein the tube is provided with one or more longitudinal slits on a side surface. 8. The method according to claim 1, wherein the lower side surface of the tube to which light is applied is roughened. 9. The method according to claim 1, wherein the tube is made of a Group VIII noble metal. 10. The method according to claim 9, wherein the tube is made of platinum. 11. A group VIII noble metal wire having a mirror-finished tip is used as a substitute for a seed crystal.
0. 12. The method according to claim 11, wherein the noble metal wire is platinum. 13. The production method according to claim 1, wherein, during the production of a single crystal, the tube is moved downward to apply a compressive force to the solid-liquid interface to stabilize the interface. 14. The method according to claim 1, wherein the raw material melt is filled in the tube by capillary action and solidified.