CS255726B1 - Method of growing single crystals of bisglycinium glycine sulphate and its isomorphs - Google Patents

Abstract

A method for growing single crystals of bis-glycinium sulfate (TGS) and its isomorphs, doped with transition metals such as platinum or palladium, on a seed in a growth solution, where a single crystal wafer with a {110} or £l2l} growth surface, on which the negative end of the spontaneous polarization vector ends, is used as a seed.

Description

The present invention relates to a process for the cultivation of single crystals of bisglycinium glycinium sulphate (TGS) and its isomorphs for the production of pyroelectric infrared detectors.

It is known to grow TGS single crystals from saturated aqueous solutions on a point or rod embryo by controlled temperature reduction of the solution. Single crystals designed to detect infrared radiation are doped with transition metal complexes such as platinum or palladium, which have the ability to induce stable zapolarization throughout the crystal volume. In the known method of growing on point or rod germs, the transition metal impurities are generally not incorporated homogeneously, so that the concentration of impurities is unevenly distributed across the different crystal growth sectors. This creates an undesirable state that some sectors are under-doped, so that the desired effect of zapolarization does not occur.

This deficiency resolves the method of growing bis-glycinium glycinium sulfate single crystals and its isomorphs doped with transition metal complexes such as platinum or palladium on a seed in a growth solution according to the present invention, which is based on the use of a TGS single crystal plate with a growth area of {lio} or {Ϊ21} at which the negative ends of the age of spontaneous polarization end.

The TGS single crystal cultivation method of the present invention allows the preparation of crystalline pyroelectrics with optimum admixture concentration, which ensures homogeneous zapolarization while maintaining the significant pyroelectric, dielectric, thermal and mechanical properties important for the successful preparation of radiation detection materials.

The solution makes use of the finding that, when the crystal grows from a solution, a nucleation in which spontaneous polarization is predetermined in a single direction due to the admixtures of glycine complexes

- 2 metals, will evoke the same orientation of the spontaneous polarization vector in the growing crystal lattice. It also takes advantage of the fact that the nature of the chemical bonds on the said charge-bound surfaces {110} or [12l} is, in comparison with other growth areas, the most favorable for incorporation of the active ingredient. The advantage of the solution is also the fact that it is not necessary to use extremely high concentrations of the admixture, which could lead to unfavorable precipitation from the growing solution and to parasitic nucleation, which degrades the quality crystallization process, loss of mechanical stability, cracking and worse workability thin plates.

The principle of solution is described on two examples:

Example 1

TGS monocrystal is prepared from a saturated aqueous solution containing a salt of the bis-sulfate glycinium glycinia [n ⁺ H3CH2COOh] 2 [ν ⁺ ₂ Η3ΟΗ ΟΟΟ ^_] · SO4, and 1.5% by weight of sodium tetrachloroplatinate Na2PtCl .. _<| .4 HgO growth on a germ with a negatively charged growth area (110). The fetus is ex. This is fixed in a frame which is immersed in a reversibly stirred growth solution, and the crystal is grown while lowering the temperature from 47 ° C to 30 ° C.

From saturated aqueous solutions containing 200 g TGS and 5.5 g Na ₂ PtCl 2, crystals homogeneously doped with Pt can be obtained. The crystals show an internal bias value, which is a measure of zapolarization, of 3 KV / cm.

Example 2

The TGS single crystal is prepared by growing from a saturated aqueous solution containing bis-glycinium glycinium sulfate salt and 2 wt% palladium sulfate PdSO4 on a seed with a negatively charged growth area (Ϊ21) by evaporating water in an enclosed crystallizer compartment & automatically condensing at temperature. 55.

Claims (1)

SUBJECT OF THE INVENTION 255 726 Method for growing monocrystals of bis-glycinium glycinium sulphate and its isomorphs doped with transition metal complexes such as platinum or palladium on a seed, characterized in that the seed used is a single crystal plate with a growth area of {110} or {Ϊ2ΐ} on which ends the negative ends of the spontaneous polarization vector.