Falling temperature method crystal growth system capable of maintaining constant supersaturation

Abstract

The invention belongs to the technical field of crystal growth, and relates to a falling temperature method crystal growth system capable of maintaining constant supersaturation. The system comprises a detection unit composed of a tension sensor and a thermoelectric couple, a control unit composed of a signal processor and a microcomputer, and an execution unit composed of a temperature controller; the system can realize real-time measurement of mass variation of the growing crystal, and can regulate the water bath to cool according to the variation, so as to make the increment of supersaturation caused by temperature falling of solution equal to the decrement of supersaturation caused by crystal growth, thus, steady and rapid growth of crystal under constant supersaturation is realized, generation of a growth layer and an inclusion is inhibited, and quality of the grown crystal is improved.

Description

technical field [0001] The invention belongs to the technical field of crystal growth, and relates to a cooling method crystal growth system for maintaining constant supersaturation, which is suitable for stable, fast and high-quality growth of crystals. Background technique [0002] The cooling method is a commonly used method for growing crystals in solution. During the crystal growth process by the cooling method, it is crucial to keep the supersaturation of the solution constant, because the fluctuation of the supersaturation of the solution may lead to the generation of growth layers and even the formation of inclusions. Therefore, maintaining a constant supersaturation of the growth solution is a prerequisite for growing high-quality crystals. [0003] In order to ensure the stable and rapid growth of crystals at a constant supersaturation, real-time measurement and control of the supersaturation of the solution is required. At present, the methods for real-time meas...

AI Technical Summary

Problems solved by technology

The size measurement method is to obtain the size of the crystal through an optical altimeter, and then calculate the quality of the crystal, calculate the supersaturation at this time according to the solubility curve and the supersaturation formula, and then lower the solution temperature to restore the supersaturation to the original level , this method is relatively simple to operate, but there may be a large deviation in the calculation of the crystal quality, because the shape of the grown crystal is not necessarily regular, which reduces the control accuracy of the supersaturation

Ultrasonic measurement method is based on the principle of different propagation speeds of sound waves in solutions of different concentrations to measure supersaturation. After indirectly measuring supersaturation according to the change of sound velocity, the supersaturation is maintained constant by cooling the solution; It can realize the automatic measurement and control of supersaturation. However, the mechanical action of ultrasonic is easy to promote the emulsification of the solution, the cavitation is easy to produce small bubbles, and there is a significant local thermal effect at high ultrasonic frequency, etc., which are not good for the stability of the solution. Therefore, This method is not suitable for solution crystal growth

The conductometric method uses the property that the conductance is sensitive to the change of the solution concentration, indirectly determines the supersaturation of the solution and guides the cooling of the solution through the functional relationship between the concentration, temperature and conductance. This method has high precision and can also cool the solution in real time to ensure The supersaturation is constant, but this method may have an electrochemical reaction due to the contact between the electrode and the solution, which affects the measurement accuracy and solution stability, and even pollutes the solution

Images