RU1819921C - Method for growing monocrystals of potassium dihydrophosphate group - Google Patents

Abstract

Usage: when growing crystals of CDR and DCDR with reduced optical absorption in the UV region of the spectrum and a reduced volume of the defective prismatic. equal area. SUMMARY OF THE INVENTION: During crystal growth, the seed is oscillated parallel to its Z axis with an amplitude of (50-90) ± 10 microns and a frequency of () ± 20 Hz. This makes it possible to reduce the optical density of crystals in the range of 200-300 nm, increase their useful volume and, accordingly, increase the yield of suitable products by 5-10% of these crystals. 1 n fs, 2 tablets, 1 ave., 3 ill.

Description

The invention relates to methods for growing water-soluble crystals, can be used to grow crystals of potassium #hydrogen phosphate and degenerated analogs with a reduced optical density of these crystals in the wavelength range of 200-300 nm, i.e. in the UV region of the spectrum.

The purpose of the invention is to reduce the optical density of crystals in the range of 200-300 nm and increase their useful volume.

This goal is achieved by the method of growing KDR and DKDR crystals, namely, in a supersaturated solution at an elevated temperature (36-42 ° C), a holder with a seed is placed, the axis of which is perpendicular to the plane of the holder, then the holder with seed is vibrated along the Z axis of the seed with the oscillation frequency of the holder in the range (60-280) ± 20 Hz and the oscillation amplitude (50-90) ± 10 μm and, according to the selected law, reduce the temperature,

This method is based on the fact that, under the selected modes of seed oscillation, the conditions for its exchange with the solution are improved, the solution molecules are ordered at the surface of the growing crystal and, as a result, the defective region in the volume of the crystal adjacent to the seed is reduced, and the optical density of the volume grown according to this crystal method.

. FIG. Figure 1 shows the dependences of the values of the absorption coefficient K on the wavelength A of light radiation for a part of the pyramid of a KDR crystal grown without oscillations of the seed 1, with vibrations of the seed with a frequency of 150 Hz and an amplitude of 50 μm 2; FIG. Figure 2 shows the dependences of the absorption coefficients K over wavelengths A of light radiation from parts of prisms of KDR and DKDR crystals grown without seed oscillations (curve 3) and with oscillations

yu yu

mi seed (curve 4) with a frequency of 150 Hz and an amplitude of 50 microns; FIG. 3 depicts the appearance of KDR and DKDR crystals on a holder with a vibrator, where 5 are the parts of the crystal pyramid, 6 is the prism part, 7 is the crystal seed, 8 is the Z axis of the seed and crystal, 9 is the near-crystal region of crystals with increased absorption coefficients, 10 - plane of the crystal holder; 11 - vibrator.

This method is based on experimental results on the growth of single crystals of CDR and DCD from supersaturated aqueous solutions with the supply of sound vibrations in the range of frequencies (F) 10-400 Tts and amplitude (p) 5-150 microns parallel to the Z axis. According to these data (see Fig. 1), single crystals grown with vibrations have a lower absorption coefficient K - In lo / l, where lo, I are the intensities

luminous fluxes in the channel of the spectrophotometer without sample (o) and after sample (I), d is the thickness of the samples, FIG. 1, curves 1 and 2 show the dependences of the K values with respect to the wavelengths (A) of the light radiation of parts of the pyramids of KDR crystals grown, respectively, without vibrations and with vibrations of the seed of these crystals. It can be seen that vibrations of the seed with an amplitude of 50 µm and a frequency of 150 Hz reduce the optical absorption of crystals in the studied range of 200-300 nm.

Similar patterns were observed for parts of the prisms of the CDR and DCDR crystals (see Fig. 2). Here, optical absorption was also reduced (up to 24%) for parts of crystal prisms grown from seeds with sound vibrations supplied to them by this method. See curve 3 for CDR single crystals grown from seed without vibrations and curve 4 for CDR single crystals grown with vibrations of amplitude of 50 µm and frequencies of these vibrations of 150 Hz.

The crystals of KDR and DKDR 1 have parts of the pyramid 5 (Fig. 3) and prism 6, which differ in the K value in the UV region of the spectrum (see, for example, curves 1 and 3 in Figs. 1 and 2). In addition, the region 9 of the seed 7 also has an increased coefficient K in the UV region of the spectrum. The value of this coefficient in the seed region has an intermediate value between the K values for parts of prisms and pyramids.

Thus, the aim of the present invention is achieved - to reduce the values of K parts of prisms, pyramids and the seed region in the UV part of the spectrum, i.e. in the range of lengths

waves of 200-300 nm. And due to the reduction in the volume of the seed region, the useful volume of the grown KDR and DCDR crystals used for the manufacture of products increases:

optical elements.

The size of the seed region with increased K values is reduced as a result of using this method to 50% of its value in crystals grown without vibrations. Thus, for crystals obtained by this method, the absorption spectra of which are shown in FIG. 1 and 2, the seed region decreased from 0.8-1.5 to 0.45-0.73 cm. This method is carried out as follows (see Fig. 3). The seed 7 with the Z axis 8, perpendicular to the plane of the holder 10, is fixed on the holder in a saturated solution of the corresponding salt. Then to the vibrator

and vibrations of a certain frequency and amplitude along the z axis of the seed are applied. Further, with an oscillating seed, according to a certain law, the temperature of the solution is reduced. As a result, the seed is growing

the corresponding crystal (5, 6) with axis Z, also perpendicular to the plane of the holder.

Frequency range (60-280) ± 20 Hz and amplitudes (50-90) ± 10 μm holder oscillations

with seed, the outcome is selected from the experimental data presented in table. 1 and 2. Similar data were obtained for the DCDR crystals, as well as for parts of the prisms of the DDR and DCD crystals

(see, Fig. 2) ..

Deviations of the seed oscillation vector from its Z axis of more than 2 ° caused the parasitization of the crystals of CDR and DCDR, as a result of which a large volume of such crystals

stalls unsuitable for the manufacture of optical elements. Therefore, the vibrations of the seed holder are directed along the Z axis of the seed.

Therefore, the use of this

method in comparison with the method of the prototype 2 allows to reduce the absorption coefficient in the UV region of crystals of KDR and DKDR by 5-24% and to reduce the defective region in the near-field region of the crystals

up to 50% of its volume obtained by the prototype method, which allows to increase the yield of optical elements from these crystals by 5-10%.

Claims (1)

The claims A method of growing single crystals of the group of potassium dihydrogen phosphate (KDR), comprising preparing a saturated solution, introducing into it a holder with a seed, the Z axis of which is perpendicular to its plane, creating supersaturation by cooling the solution and crystal growth, characterized in that that, in order to reduce the optical density of crystals in the range 200-300 nm and increase their useful volume, the holder with the seed is subjected to vibrations along its axis with a frequency of (60-280) ± 20 Hz and an amplitude of (50-90) ± 10 μm. Table 1 Relative changes in the absorption coefficients (A K / K) of the parts of the pyramids and the change in the volume (AV / V) of the near-seed region of KDR crystals grown according to the proposed method with an amplitude of the oscillations of the seed of 50 μm table 2 4 Relative changes in the absorption coefficient (DK / K) of the parts of the pyramids and changes in the volume (AV / V) of the near-seed region of the CDR crystals. grown by the proposed method with seed oscillation frequency of 100 Hz depending on the amplitude (h) these vibrations, relative to these crystal parameters KDR grown without seed hesitation 4 3 U h FIG. 3