Method for producing organic crystal and crystal growth cell therefor

Abstract

A method for producing an organic crystal is disclosed. One embodiment comprises maintaining a capillary tube containing a fused liquid of an organic crystal material and having a fused liquid reservoir at one end thereof at a temperature not less than the fusion point of the organic crystal material together with the fused liquid reservoir, reducing the temperature of the fused liquid in the fused liquid reservoir to precipitate seed crystals, and then slowly cooling the capillary tube successively from the end toward the other end to allow a single crystal to grow from the seed crystal in the capillary tube. Because of the large quantity of the fused liquid, a seed crystal can be formed and allowed to grow even from a fused liquid of an organic crystal material which hardly crystallizes in the form of a fused liquid. Another embodiment comprises charging a solution of an organic crystal material in a capillary tube under heat, rapidly reducing the temperature of one end of the capillary tube to precipitate polycrystals, and then slowly cooling the capillary tube successively from the end toward the other end to allow a single crystal to grow from the polycrystal as a seed crystal. A seed crystal grows from a solution of an organic crystal material under control of crystal form to obtain a single crystal which has no inversion symmetry center, is free from lattice defect or rearrangement, and less causative of a laser beam loss.