Method of growing single crystals of quartz

 

(57) Abstract:

The invention relates to methods of producing synthetic single crystals of quartz and hydrothermal solutions by temperature variation and can be used to obtain high-quality optical quartz used in opto-mechanical and electronic industry. The inventive single-crystal quartz is grown by the hydrothermal method from alkaline solutions by recrystallization of quartz charge from the charge container is horizontally placed on the shielded bare plate in the presence of a temperature differential between the camera of growth and dissolution, using multiple charge the container with perforated partitions in height, each of which is the bottom of the next section, and the growth is carried out at the screening of the top and end faces of the bare plate with a gasket made of steel foil between the screen and the seed plate, where at the beginning of the growth cycle conduct the etching solution of 25-40 MPa at a constant temperature of synthesis, and after completion of the cultivation process carry out the cooling of the autoclave with a rate of 8-10oC/h to a temperature of Denia to a temperature of 120oWith, at which disables the power supply to the heaters of the autoclave. The technical result of the invention is to provide a high-quality optical quartz. table 1.

The invention relates to methods of obtaining crystals, in particular to methods of producing synthetic single crystals of quartz of hydrothermal solutions using temperature gradient. The proposed method can be used to obtain high-quality optical quartz used in opto-mechanical and electronic industry.

A method of obtaining synthetic single crystals of quartz from aqueous alkaline solution under hydrothermal conditions at a temperature differential between the chambers of the growth and dissolution (U.S. Pat. USA 3291575; NCI: 23 - 301R, 1965) in a vertical autoclave, divided by the camera dissolution containing the mixture, and the growing chamber, placed in it by the seed crystal plates installed so that the main growing surface oriented vertically and the end faces of the bare plate is blocked by the screen.

However, the vertical position of the seed plates in the growing chamber of the autoclave is haunted by reducing their quality, and also hampers the stable growth process, because of the impossibility of maintaining during the entire cycle of crystallization constant mass transfer between the camera of growth and dissolution, leading to lowering of the technical properties of the grown crystals.

The closest technical solution of the present invention is a method of production of synthetic single crystals (C. The UK 1443835, B 01 J 17/04, 1974), including the synthesis of quartz of hydrothermal alkaline solutions in the autoclave by recrystallization of quartz mixture of monoclonal charge container located in the lower part of the autoclave chamber dissolution, horizontally placed in the cell growth of the bare plate with shielding their top growth surfaces, in the presence of a temperature differential between the camera of growth and dissolution.

The disadvantages of this method are: the impossibility of maintaining during the entire cycle of crystallization constant, intensive convection mass transfer, which leads to destabilization of the growth parameters and the decrease of the technical characteristics of the obtained crystals; rather high concentration in the resulting crystal premediation stability of quartz crystal.

The technical object of the present invention is to improve the quality of grown crystals of quartz for use in modern optoelectronic devices.

The technical problem is solved due to the fact that in the known method of growing single crystals of quartz hydrothermal method from alkaline solutions by recrystallization of quartz charge from the charge container is horizontally placed on the shielded bare plate in the presence of a temperature differential between the chambers of growth and dissolution, use multiple charge the container with perforated partitions in height, each of which is the bottom of the next section, and the growth is carried out at shielding the top and end faces of the bare plate with a gasket made of steel foil between the screen and the seed plate, where at the beginning of the growth cycle to produce the etching solution of 25-40 MPa at a constant temperature growth, and after completion of the cultivation process, carry out the cooling of the autoclave with a rate of 8-10oC/h to a temperature of 270oC and pressure of 10 MPa, and then produce the final etching solution at the same pace, ohlord is SS="ptx2">

Comparative analysis of the proposed technical solution with the prototype shows that the inventive method differs from the known fact that the method uses multiple charge the container with perforated partitions in height, each of which is the bottom of the next section; spend 3-party screening of the bare plate - upper and end surfaces of the strip of steel foil between the screen and the seed plate; at the beginning of the growth cycle performed by the etching solution of 25-40 MPa at a constant temperature of synthesis, and after completion of the cultivation process carry out the cooling of the autoclave with a rate of 8-10oC/h to a temperature of 270oC and pressure of 10 MPa, and then produce the final etching solution at the same cooling rate to a temperature of 120oC, at which a power heaters autoclave. Thus, the claimed method meets the criteria of the invention of "novelty". In the known technical solutions obtain single crystals of synthetic quartz is not high enough quality for use in optoelectronics. The proposed method of synthesis of quartz allows to significantly improve the quality of the differences".

Use in the synthesis of single crystals of quartz multicell charge container with perforated partitions in height, and each of which is the bottom of the next section, the so-called "etaziranoj" design provides effective permanent dissolution of the charge during the whole cultivation cycle over the entire height of the container, thereby stimulating the mass transfer and, accordingly, the rate of crystal growth, resulting in higher quality material.

Shielding the top and end faces of the bare plate provides capacity single crystal growth sector on the lower main surface of the crystal plate, which eliminates the process of forming the upper defective half of the crystal, and maintains a constant free volume in the autoclave due to the lack of expansion of the end faces of the seed, where the movement of convection currents, providing a constant mass transfer between the zones of growth and dissolution required for growing defect-free single crystals. Install a strip of steel foil between the screen and the seed plate prevents the formation of cracks in the growing cu is the temperature of synthesis causes a lowering of the impurity concentration of aluminum, falls into the crystal from hydrothermal solution that will adversely affect sensing parameters, the homogeneity of the refractive index and optical radiation stability of the grown crystals. Specific parameters grazing selected empirically and provide the maximum effect.

This mode of cooling of the autoclave after the process of cultivation, namely, the cooling of the autoclave with a rate of 8-10oC/h to a temperature of 270oC and pressure of 10 MPa, after which a final etching solution at the same cooling rate to a temperature of 120oWith and disconnecting power to the heaters of the autoclave, provides an exception deposition on the surface of the grown crystals thick leave-silicate plaque, preventing viewing of the crystals in the grading and evaluation of their quality.

The proposed method of growing single crystals of quartz implemented in the following way.

Example. The crystal growth is carried out in an autoclave with a capacity of 1500 liters In the bottom area of the camera dissolution placed pre-loaded multiple-charge container, the height of which has perforated walls. Naprilene bottom of the next section. Thus, the volume of the container is divided in the height section. The charging of the charge container fragments of vein quartz size 2-5 mm carried out, starting with the bottom section in the upward direction. After downloading the next section above the charge set rigidly fixed perforated septum, which serves as the bottom of the next section over loaded. Therefore, in each section is a sample of the charge material. The total weight of the loaded charge is 500 kg After installation in the lower part of the autoclave container with the charge on it is placed a perforated disk "aperture" hole size 16-25 mm and a density of 3% of the total area of the diaphragm, which separates the autoclave at the camera dissolution and growth chamber and designed to create the optimum temperature differential between the chambers of the dissolution and growth. Then in the growing chamber is placed in Kristallografiya horizontally placed on the bare plate cut from a single crystal of quartz, the top growing and the end faces are shielded. Between the screens and the seed plates is placed a thin strip of steel foil (thickness 0.4 mm). After loading into the chamber of the dissolution of the charge, installation dia is ielem, for example, soda solution. Tightly close it, include electric heating elements and is heated to thermobaric parameters necessary for carrying out crystallization: crystallization temperature of 347oWith the temperature of dissolution of the charge 350oWith a pressure of 150 MPa. When reaching the specified parameters at the beginning of the growth cycle, produce partial etching solution through the valve high pressure in an amount to provide a pressure drop in the autoclave at 25-40 MPa at a constant temperature of synthesis. Then lead the process of growing crystals within 200 days. Then start the output of the autoclave mode cooling with a rate of 8-10oC/h, which achieve a gradual reduction in the power current supplied to the electric heaters. In the process of cooling is reduced as well and the pressure in the autoclave. When the temperature reached 270oC and pressure of 10 MPa spend the final etching solution at the same cooling rate. At a temperature of 120oWith no pressure in the autoclave etching solution is stopped, the autoclave is disconnected from electric heating, and further cooling takes place with an arbitrary rate. When the autoclave has cooled to a temperature thrillvania solution at the beginning of growth and at different rates of cooling of the autoclave shown in the table.

The proposed method allows to obtain high-quality single crystals piezooptical quartz practically free of dislocations, free from optical inhomogeneities, which are widely used in modern optoelectronic devices.

Method of growing single crystals of quartz by hydrothermal synthesis method of alkaline solutions, quartz recrystallization of the mixture from the charge container is horizontally placed on the shielded bare plate in the presence of a temperature differential between the chambers of growth and dissolution, characterized in that use multiple charge the container with perforated partitions in height, each of which is the bottom of the next section, and the growth is carried out at the screening of the top and end faces of the bare plate with a gasket made of steel foil between the screen and the seed plate, where at the beginning of the growth cycle conduct the etching solution of 25-40 MPa at a constant temperature growth, and after the completion of the process of growing autoclave is cooled with a rate of 8-10oC/h to a temperature of 270oC and pressure of 10 MPa, and then release the entire solution at the same cooling rate d

 

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FIELD: crystal growth.

SUBSTANCE: diaphragm is made of two interconnected metallic disks arranged one above the other. The bottom disk is mounted at the top boundary of the solution zone of charge and provided with an opening at the center. The top disk is mounted at the bottom boundary of the zone of crystal growth and provided with openings distributed throughout the surface of the disk. The diameters of the openings in the bottom disk are 1-75% of the diameter of the disk.

EFFECT: enhanced quality of crystals.

6 cl, 3 dwg

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