Structural, Optical and Mechanical Properties and Cracking Factors of Large-Sized KBr:Ce3+ Single Crystal

Large-sized Ce3+ doped KBr crystal was grown using the resistance heating Czochralski method. The material has more well-defined optical and mechanical properties than the pure KBr single crystal. The structural, optical properties and quality of the grown KBr:Ce3+ crystal were investigated by x-ray diffraction (XRD), optical absorption, photoluminescence (PL), PL excitation spectroscopy, micro-hardness and stress measurements. The XRD data indicated that the KBr host lattice changed when Ce ions were incorporated. Optical absorption and PL measurements confirmed the presence of cerium ions in the doped KBr crystal. A broad and intense blue emission around 394 nm, attributable to the transition from the 5d excited state to the 4f ground state of the Ce3+ ions, was observed in the PL emission. The hardness of the KBr:Ce3+ crystal was greater than that of the pure KBr crystal. The stress values of different parts in the crystal were different, and the stress was mainly dependent on the process parameters. High stresses were always found to exist near the growth interfaces, at the shoulder-expanding locations, the tailing locations and the sites where the diameters undergo sharp changes. The optimized process parameters were the main measures to avoid the crack of the large-sized KBr:Ce3+ crystal. These observations indicate that the KBr:Ce3+ crystal is a promising material for use in optical, dosimetry and scintillation applications.