Study on the growth and processing technology of large-size KCl0.5Br0.5 crystal

A high-quality KCl0.5Br0.5 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 KCl0.5Br0.5 crystal indicates that the deliquescence of KCl0.5Br0.5 crystal strongly depends on the temperature and humidity and the deliquescence of the crystal has been proved to be a physical process by carrying out X-ray diffraction (XRD), atomic force microscopic (AFM), and energy dispersive 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 KCl0.5Br0.5 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 element 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.