Modified vertical Bridgman method: Time and cost effective tool for preparation of Cs2HfCl6 single crystals

• Published in: Journal of crystal growth 2020-03, Vol.533, p.125479, Article 125479
• Main Authors: Vanecek, V., Kral, R., Paterek, J., Babin, V., Jary, V., Hybler, J., Kodama, S., Kurosawa, S., Yokota, Y., Yoshikawa, A., Nikl, M.
• Format: Article
• Language: English
• Subjects: A1. Characterization; A1. Crystal structure; A2. Bridgman technique; B1. Halides; B2. Scintillator materials; Bridgman method; Cesium; Chlorides; Crystal growth; Crystal pulling; Crystal structure; Crystallography; Crystals; Hafnium; Optical properties; Photoluminescence; R&D; Research & development; Scintillation counters; Screening; Single crystals
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2020.125479

•Cs2HfCl6 single crystal preparation by miniaturized and standard Bridgman methods.•Cs2HfCl6 single-phase proved by XRD measurements.•Room temperature optical, luminescence, and scintillation properties of Cs2HfCl6.•Room temperature photoluminescence and scintillation decay kinetics of Cs2HfCl6. Time and cost effective methods are highly desirable in research and development of new scintillators. Modern techniques like micro-pulling down (μ-PD) are suitable for material screening but are unfit for the growth of some crystals. These crystals must be grown by different methods that are usually very time demanding. Modification of halide μ-PD apparatus by custom made elements allowed us to grow cesium hafnium chloride (Cs2HfCl6) by vertical Bridgman method (VB) with significantly reduced growth time. Structural and optical properties of samples prepared from as-grown crystals were studied and compared to crystals grown by standard VB method. The X-ray diffraction confirmed the formation of cesium hafnium chloride single-phase and natural cleavage of the crystals along the (1 1 1) crystallographic plane. Photoluminescence emission, excitation, absorption, and radioluminescence spectroscopy revealed that the optical quality of the crystals grown by modified VB method was comparable to the quality of the crystals grown by standard VB method. Therefore we can use samples prepared by modified VB to estimate and optimize the performance of Cs2HfCl6 based crystals in scintillation detectors. This setup allows the time and cost-effective material screening and it is a powerful tool for the development of new halide based single crystal scintillators.