SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF SCINTILLATION SINGLE CRYSTALS OF CESIUM HEXACHLOROHAFNATE Cs2HfCl6

A synthesis procedure of crystalline cesium hexachlorohafnate from cesium chloride and hafnium oxychloride octahydrate in a hydrochloric acid solution is developed. The structure of the crystals grown is studied by the energy dispersive elemental analysis, powder and single crystal X-ray diffraction. It is shown that a set of crystals is not homogeneous in composition, however, the main phase present in the composition (about 90%) is Cs 2 HfCl 6 . An additional phase found in the composition is CsCl. The atomic structure of Cs 2 HfCl 6 is determined on single crystals for the first time. The structure is refined in the space group , Z = 4. The unit cell parameter of Cs 2 HfCl 6 is a = 10.399(3) Å. Interatomic distances are analyzed in the Cs 2 HfCl 6 structure. The scintillation activity of the grown crystals is examined. The light yield of the synthesized compound is found to be about 19·10 3 photon/MeV.