Study on the growth and processing technology of large-size KCl_(0.5)Br_(0.5) crystal

摘要

A high-quality KCl_(0.5)Br_(0.5) crystal has been grown by using the resistance heating Czochralski (Cz) method under the best process parameters (rotating speed: 6-8 r/min, pulling speed: 1-2 mm/h, circulating water temperature: 28 ± 1 °C, cooling rate: 8-10 °C/h, and axial temperature gradient: 1-2 °C/mm). The deliquescence analysis of the KCl_(0.5)Br_(0.5) crystal indicates that the deliquescence of KCl_(0.5)Br_(0.5) crystal strongly depends on the temperature and humidity and the dehquescence of the crystal has been proved to be a physical process by carrying out X-ray diffraction (XRD), atomic force microscopic (AFM), and energy dis-persive X-ray spectroscopic (EDX) measurements. The results of the polishing fluid composition experiment have shown that the best polishing fluid composition is 'water + ethanol + surfactant X', and the best ratio between them is 87.5∶9.5∶3.0. The effects of polishing pressure, polishing disk speed, polishing fluid flow rate, and polishing time on the removal rate and roughness of the KCl_(0.5)Br_(0.5) crystal surface have been analyzed. The best parameters found for the crystal processing are the optimal pressure is 0.1042 MPa, the polishing fluid flow rate is 15 ml/min, the rotating speed of the polishing disk is 30 r/min, and the polishing time is 20 min. The performance test of the polished crystal ele-ment has shown that the transmittance of the crystal with a thickness of 4 mm is 91.7%, and the surface roughness of the crystal is 3.96 nm. Results obtained in the present study provide the technical route and experimental support for the processing of soft and moisture-prone crystals.