RU1808887C - Method for crystal production - Google Patents

Abstract

Usage: in optics and electronic devices as converters of the main laser radiation. SUMMARY OF THE INVENTION: concentrated sulfuric acid is added to an acidic crystal growth solution, as a result of which the pH of the solution is reduced to 3.8-3.9. Then, by lowering the temperature to 26-32 ° C; C, crystals are grown on a point seed mounted on a platform rotating at a speed of 40-60 rpm. Optically homogeneous crystals are obtained with dimensions along the 100 axis of the order of 15-24 mm. 1 wp

Description

The invention relates to a technology for producing x60C (NH2) 2 HaO single crystals, which can be used in optics and electronic devices as primary laser radiation converters. They are capable of generating a second harmonic on the radiation of an Nd: YAG laser.

The aim of the invention is to increase the size of crystals and reduce defects in them.

The goal is achieved in that the growth is carried out from solutions previously treated with sulfuric acid to 8-3.9; cultivation is carried out by lowering the temperature in the low temperature range of 32-26 ° C; the spot seed is mounted on a platform rotating at a speed of 40-60 rpm.

The solution 2nS04 -60C (prepared on the basis of the state diagram of the starting products of ZnSO-g 7H20 and

OC (NH2) 2 grade AXI on bidistilled water. The molar ratio of ZnS04 to OC (NH2) 2 is 1: 6. The solution was stirred in the mold for one day. The synthesis temperature is about 10 ° above the saturation temperature. The pH of the solution saturated at 30 ° C is 5.15. Sulfuric acid is added to the prepared solution at the rate of 1 ml of 98% H2S04 per 100 ml of solution. In this case, the pH of the solution decreases to 3.8-3.9. The acidified solution is filtered, poured into the crystallizer and its saturation temperature is refined. The latter should be about 30 ° C. Then the solution is again superheated and kneaded for two days to dissolve all the fine particles that can serve as crystallization centers during the growth. The resulting solution is filtered and a crystallization process is carried out.

The introduction of acid into the solution to reduce the alkalinity of the solution prevents

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the appearance in the solution of a substance of a different phase creates the best conditions for crystal growth.

As the pH of the solution decreases to below 3.8, small gas bubbles appear in the solution, which, during crystal growth, can be included in it, which leads to a deterioration in the quality of the grown single crystal. It is also impractical to conduct the process of growing a crystal from solutions having a pH above 3.9. Since at this pH value, a finely dispersed phase is formed in the solution, which interferes with the growth of the single crystal.

When grown by lowering the temperature, a temperature range of 32-26 ° C is optimal for a given crystal. At temperatures above this range, a finely dispersed phase forms in solutions after a few days. Carrying out growth at temperatures lower than this range requires the use of refrigeration units and at the same time the crystal growth rate is reduced. Crystal growth by lowering temperature allows more precise control of the growth process. Temperature is controlled by a contact thermometer. The average rate of decrease in temperature is 0.2 ° C / day.

The growth of a crystal on a point seed mounted on a rotating platform creates favorable hydrodynamic conditions for growth. It is not practical to carry out the growth process at a platform rotation speed of less than 40 rpm, since the crystal growth rates are reduced. An increase in the platform rotation speed above 60 rpm leads to the formation of a funnel in the solution, splashing of the solution, as a result of which parasitic crystals form.

Example 1. 117.72 g of OCCNHab was taken to prepare a ml of solution. 94.011 g of ZriSCM 7H20 and 28.5 ml of NaO. The solution was synthesized at C. A day later, 1.4 ml of 98% HaSCU was added to freshly prepared solution c, 15. After acidification, the pH dropped to 3.8. The solution overheated to. The solution was filtered, the saturation temperature was determined (, 7 ° C). The solution was measured for two days at a time. The growth process lasted 20 days. A crystal was obtained without visible defects with a size along the 100 axis of 24 mm. The final temperature was 26.7 ° C.

PRI me R 2. For the preparation of 100 ml of a solution, 78.58 g of OC (NH2) 2, 58.7 g

ZnSCM 7H20 and 17.5 ml of H20: The solution was prepared as in Example 1. To a freshly prepared solution with 15 portions was added 1 ml of 98% H2S04. At

pH 3.85 saturation temperature, 2 ° C. Cultivation lasted 20 days. The average rate of temperature decrease was 0.2 ° C / day. A crystal was obtained without visible defects with a maximum axis size of 19 mm.

The final temperature is 27.2 ° C.

Example 3. 68.98 g of OS (MH2) 2 were taken. 55.04 g of ZnSCM-7H20 and 19.5 ml of N26. The whole procedure was carried out analogously to examples 1, 2. In freshly prepared

solution c, 05 added 0.9 ml of 98% H25Cm. At the same time, 8. Saturation temperature, 45 ° C. The growth process lasted 7 days. The size of the obtained crystal along the 100 axis is 15 mm. The crystal is optically homogeneous. The average rate of temperature decrease is 0.2 ° C / day. The final temperature of the solution is 28 ° C.

Example 4. The preparation of the solution was carried out analogously to Example 2. The solution was not treated with sulfuric acid (, 15). The saturation temperature of the solution was 4 ° C. When the crystal was grown on the seventh day after synthesis, a finely dispersed phase formed in the solution. The growing crystal began to include small particles. Many parasitic crystals appeared at the bottom of the mold and on the platform. Growth lasted 20 days. Average temperature drop rate

0.2 ° C / day. The grown crystal is defective, opaque. Axis size 100 16 mm. The final temperature is 26.9 ° C.

Example 5. 117.72 g of OC (NH2) 2, 94.91 g of ZnS04 7H20 and 26 ml of H20 were taken.

The solution was synthesized in a crystallizer at C. Two days later, before the addition of acid, a finely dispersed phase formed in the solution. The saturation temperature of the solution, 4 ° C. The solution is not suitable for

growing crystals.

Thus, the treatment of freshly prepared solutions with sulfuric acid and

crystal growth relatively when

low-temperature interval provides high-quality crystals suitable for generating a second harmonic by laser radiation,

Claims (1)

1. The method of obtaining crystals ZnSCU -60C (NH2) 2 -H20, comprising preparing an acidic solution and crystal growth by lowering its temperature, characterized in that. in order to increase the size of the crystals and reduce The solution according to claim 1, characterized by 3.8-3.9 by adding concentrate to it, that the seed is placed on paid sulfuric acid and the growth is carried out on a form that rotates at a speed 40-point seed at 26-32 ° C. 60 rpm.