Variable-diameter autoclave for hydrothermal method crystal growth

Abstract

The invention discloses a variable-diameter autoclave for hydrothermal method crystal growth. The variable-diameter autoclave comprises an autoclave body, a dissolving area and a crystallizing area are located in an inner cavity of the autoclave body, and the diameter of the crystallizing area in the autoclave body is larger than that of the dissolving area in the autoclave body. The variable-diameter autoclave has the advantages that due to the structure that the diameter of the crystallizing area in the inner cavity of the autoclave body is designed to be larger than that of the dissolving area in the inner cavity of the autoclave body, on one hand, compared with a traditional autoclave with the same height and outer diameter as the variable-diameter autoclave, the capacity of the inner cavity of the autoclave body is increased, crystals can continuously grow in the same autoclave body in multiple periods, a lot of problems caused by frequent replacement of autoclaves are solved, and cost can also be saved; on the other hand, the crystallizing area in the autoclave body is located above the dissolving area, the diameter of the crystallizing area is larger than that of the dissolving area, the intensity of gas-liquid convection of the inner cavity of the autoclave body is relieved effectively, crystal growth is facilitated, and the loading quantity of nutritive salt in the crystallizing area can also be increased.

Description

technical field [0001] The invention relates to a device for growing crystals by hydrothermal method, in particular to a variable-diameter autoclave for growing crystals by hydrothermal method. Background technique [0002] The research on the method of artificially growing crystals began as early as the end of the nineteenth century, and has a history of nearly a hundred years. The methods of growing single crystals mainly include flux method, hydrothermal method, gas phase method, zone melting method, etc., among which thermal The crystals grown by the liquid method have the characteristics of small thermal stress, small macroscopic defects, good crystal uniformity, and high transmittance. The hydrothermal crystallization technology refers to that a solvent is placed in a sealed pressure vessel, and a chemical reaction is carried out under high temperature and high pressure conditions. Specifically, the raw material (solute) is dissolved in the solvent, and appropriate mea...

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Problems solved by technology

Since the caliber of the dissolution zone and the crystallization zone are the same, the loading amount of nutrients per unit time in the crystallization zone is low, the change of supersaturation of the solution is not obvious, and the crystallization is slow, resulting in a low crystal growth rate; on the other hand, due to the crystallization zone and the dissolution zone The caliber of the zone is the same, the overall space in the kettle is narrow and the gas-liquid convection is severe during the growth process, which leads to the instability of the crystallization process and the low crystallization efficiency; The distance between the high-temperature superheated solution rising in the middle dissolution zone and the seed crystal in the growth zone is relatively close, and even the seed crystal is immersed in the solution, which easily causes the corrosion phenomenon of the seed crystal; finally, the crystallization zone and the dissolution zone of the traditional autoclave have the same caliber, and the autoclave body is longer. It will cause uneven crystal growth speed from top to bottom in the same tank, and more seriously, it will also cause inconsistent crystallization speed of the same single crystal in the vertical direction

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