The Bridgman method growth and spectroscopic characterization of calcium fluoride single crystals

Abstract

It must be noted that the main objective of this study was to obtain single crystals of calcium fluoride - CaF2, and after that the crystals were characterized with various spectroscopic methods. The crystals were grown using the Bridgman technique. By optimizing growth conditions, <111> oriented CaF2 crystals up to 20 mm in diameter were grown. Number of dislocations in CaF2 crystals was 5?104 - 2?105 per cm2. Selected CaF2 single crystal is cut into several tiles with the diamond saw. The plates were polished, first with the silicon carbide, then the paraffin oil, and finally with a diamond paste. The obtained crystal w?s studied by Raman and infrared -IR spectroscopy. The crystal structure is confirmed by X-ray diffraction (XRD). One Raman and two IR optical modes predicted by group theory are observed. A low photoluminescence testifies that the concentration of oxygen defects within the host CaF2 is small. All performed investigations show that the obtained CaF2 single crystal has good optical quality, which was the goal of this work.