JPH02307885A - Single crystal producing device - Google Patents

Abstract

PURPOSE:To uniformize the temp. in an autoclave and to eliminate the fluctuations in thickness, crystallinity, etc., between grown crystals by forming the raw material installing section and seed crystal installing section of the single crystal producing device of a hydrothermal synthesis crystallization method as respectively separate and independent parts. CONSTITUTION:A pressure vessel 1 for installation of the seed crystal and a pressure vessel 2 for installation of raw materials are connected by two pieces of upper and lower transporting pipes 6, 7. The seed crystal 4 is installed via a supporting frame 3 into the vessel 1. The raw material crystals ground to suitable sizes are put into a raw material cage 5 in the vessel 2. Spaces are provided in the lower part of the frame 3 and the cage 5 to avoid disturbing the flow of a soln. The temp. in the pressure vessel is uniformly maintained by growing the single crystal by the hydrothermal synthesis crystallization method using this single crystal producing device and, therefore, the specified size of the crystal (thickness of the growing part) in the same pressure vessel is obtd. The uniform thickness of the growing part in the same crystal is similarly obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a single crystal manufacturing apparatus using a hydrothermal synthesis method which is widely used for growing crystals of quartz, beryl, berlinite, etc.

[Summary of the invention]

The present invention provides a single crystal growth apparatus using a hydrothermal synthesis method that is useful as a growth apparatus for various single crystals, by separating and independent of a pressure vessel in which a raw material is installed and a pressure vessel in which a seed crystal is installed.
By stabilizing the temperature within each pressure vessel and making it easier to create a temperature difference between the pressure vessels, it is possible to grow larger crystals of better quality.

[Conventional technology]

Conventionally, in addition to the hydrothermal synthesis method, various growth methods such as the Czochralski method, the floating zone method, the flux method, and the Bernoulli method have been used to grow single crystals.

Among these methods, hydrothermal synthesis has the potential to grow single crystals of the highest quality.

Hydrothermal synthesis is a method of synthesizing materials using an aqueous solution in an autoclave at a predetermined temperature and pressure, and is used for mass production of artificial quartz. Single crystal production equipment currently used in hydrothermal synthesis uses a pressure vessel called an autoclave. This autoclave has a cylindrical shape, with raw materials placed in the lower part of the autoclave and seed crystals placed in the upper part. Further, a temperature control device called a baffle plate is installed between the raw material section and the seed crystal section.

This baffle plate is installed to create as discontinuous a temperature difference as possible between the raw material portion and the seed crystals by controlling convection within the pressure vessel.

[Problem to be solved by the invention]

In conventional single crystal growth equipment using hydrothermal synthesis, raw materials and seed crystals are placed in the same autoclave.
Although a baffle plate was provided, it had the disadvantage that it was difficult to create a temperature difference due to the influence of convection. Furthermore, there is a drawback that there is a temperature difference between the upper and lower sides of the baffle plate, that is, inside the seed crystal installation section and the raw material installation section.

These defects had a very large effect on the crystal. First, in the same autoclave, the crystal growth speed may be different between a seed crystal placed in the upper part and a seed crystal placed in the lower part (near the panfur plate).

In other words, the upper seed crystal has a large temperature difference with the raw material installation area, resulting in thick crystals in the growth area, and the lower seed crystal has a small temperature difference with the raw material installation area, resulting in thin crystals in the growth area. is created. For this reason, the same autoclave produces crystals of different quality.

Second, there is a difference in the thickness of the grown portion between the top and bottom of one grown crystal. Generally, in hydrothermal synthesis, seed crystals are placed vertically. Therefore, even on the same seed crystal, the growth rate is faster in the upper part, so the upper part becomes thicker.

[Means to solve the problem]

The problem that there is a difference in growth speed with conventional methods is due to the structure of the single crystal growth apparatus.

In order to solve these problems, we have discovered a single crystal manufacturing apparatus in which the raw material installation section and the seed crystal installation section are separated and independent.

[Effect]

In the hydrothermal synthesis method, starting materials are dissolved in an aqueous solution of an appropriate solvent at an appropriate temperature and pressure, and the temperature difference is used to transport nutrients to form crystals or deposit them on an appropriate substrate. to develop. The single crystal grown in this way has no inclusions or cracks, and
It is required that there be no variation between single crystals, and that there be no variation in thickness, crystallinity, etc. within a single crystal.

A single crystal manufacturing apparatus according to the present invention has been discovered as an apparatus that satisfies such requirements.

〔Example〕

Fig. 1 shows a sectional view schematically showing the configuration of this embodiment.
The seed crystal installation pressure vessel 1 and the raw material installation pressure vessel 2 are connected by two upper and lower transport vibes 7.8. A seed crystal 4 is installed inside the seed crystal installation pressure vessel l via a seed crystal support frame 3. A space is provided at the lower part of the seed crystal support frame 3 so as not to obstruct the flow of the solution.

Further, inside the raw material installation pressure vessel 2, raw material crystals pulverized to an appropriate size are placed in a raw material basket 5.

The surface area of this raw material crystal is suitably about five times the surface area of the seed crystal. A space is also provided at the bottom of this raw material basket 5 so as not to impede the flow of the solution.

As the seed crystal 4, Z temporary (0
001) surface was used. Four seed crystals were placed as shown in the figure. As a raw material, crushed Las Chikara (natural crystal from Brazil) was used.

Crystals were grown using the above settings.

Example a Temperature inside pressure vessel 1: 340°C Temperature inside pressure vessel 2: 360°C Solvent:
−−−−・・−0, 5 mol NazOHff aqueous solution pressure car −−−−−−−−−−1−−−・−・・−・・1000kg/aJ growing period・
−−−１−・−・・−−〜−−−−・・−・・・・・−・
As a result of growing under the above conditions for 20 days, crystals were grown on the seed crystals 4. The results and properties are shown below.

Thickness of grown layer・・・・・・−・−・・・・11,
O-ryu (no variation in thickness among the same crystals and 4 crystals) Growth rate -・-・--・--・--・---1・-・
・Characteristics of the layer grown by 550%/day ・・・・・・−・−・
-5iO□ single crystal, very few inclusions and microcracks.

Example: Temperature inside pressure vessel 1: -340°C Pressure vessel 2
Internal temperature of −, 355℃ Solvent −−−−−−
-----・-0, 5 mol NazOH3 aqueous solution pressure car --
−−−−−−−−−−−−−・−・−・−・・・−−−
--800kg/c4 breeding period・・・・・・・・・・・・・
-1--... -- As a result of growing under the above conditions for 20 days, a crystal was grown on the seed crystal 4. The results and properties are shown below.

The thickness of the grown layer is 9, 6 (
(There is no variation in thickness among the same crystal and four crystals) Growth rate --- m = --- 480-7 days Properties of the layer grown --- --- --5i O□ Single crystal, inclusions, and micro cranks are very few.

〔Effect of the invention〕

As described above, according to the present invention, the temperature inside the autoclave is kept uniform compared to crystal growth using conventional single crystal manufacturing equipment, so that the size of the crystal within the same autoclave can be reduced. thickness) becomes constant. Further, the thickness of the crystal growth part in the same crystal is also constant. This improves the quality of the grown crystal and eliminates variations. Conventionally, crystals that can be used as products, crystals that cannot be used as products, and parts that can be used as products,
Although there were some variations in the number of parts that could not be achieved, the present invention can almost eliminate these variations. In addition, we are now able to supply crystals more stably,
The effect is extremely large.

Furthermore, although this example describes the growth of quartz crystal, it is not limited to quartz crystal, but aquamarine single crystal (Be:+/Vz(si
03), ), analcite single crystal (NaAZSi20
・)+20) For growing single crystals using hydrothermal synthesis methods such as
It goes without saying that the device of the present invention is effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the pressure vessel in the apparatus of the present invention. 1.2...Pressure vessel 3...Seed crystal support frame 4...Seed crystal 5...Raw material basket 6.7...Transportation pipe and above Applicant Seiko Electronic Industries Co., Ltd. Agent Patent attorney Takashi Hayashi Nosuke Figure 1

Claims (2)

[Claims] (1) Single crystal production in a hydrothermal synthesis apparatus for growing single crystals in various aqueous solutions by applying a predetermined temperature and pressure, characterized in that the raw material installation pressure vessel and the seed crystal installation pressure vessel are separated and independent. Device. (2) The single crystal production apparatus according to claim 1, wherein the raw material installation pressure vessel and the seed crystal installation pressure vessel, which are separated and independent, are connected by a solution transport pipe provided at the upper and lower parts. .