Growth and luminescent properties of Ce and Eu doped Cesium Hafnium Iodide single crystalline scintillators

• Published in: Journal of crystal growth Vol. 492; pp. 1 - 5
• Main Authors: Kodama, Shohei, Kurosawa, Shunsuke, Yamaji, Akihiro, Pejchal, Jan, Král, Robert, Ohashi, Yuji, Kamada, Kei, Yokota, Yuui, Nikl, Martin, Yoshikawa, Akira
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.06.2018; Elsevier BV
• Subjects: A1. X-ray diffraction; A2. Bridgman technique; A2. Growth from melt; A2. Single crystal growth; Atomic properties; B2. Scintillator materials; B3. Scintillators; Bridgman method; Cerium; Cesium; Crystal growth; Crystal structure; Crystallinity; Decay rate; Diffraction; Europium; Gamma rays; Hafnium iodides; Luminescence; Optical properties; Photons; Scintillation counters; Single crystals; X-rays; A2. Bridgman technique; B3. Scintillators; A1. X-ray diffraction; B2. Scintillator materials; A2. Single crystal growth; A2. Growth from melt
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2018.03.033

•Crystal growth and scintillation properties of Ce and Eu-doped Cs2HfI6 scintillator were investigated.•The crystals were grown by the vertical Bridgman-Stockbarger method.•Obtained crystals were single crystals with Cs2HfI6 single phase.•The measured light output and decay time of Ce:Cs2HI6 were ∼48,000 photon/MeV and 2.3 ± 0.1 µs, respectively.•As for Eu:Cs2HI6, light output and decay time were measured as ∼69,000 photon/MeV and 2.8 ± 0.1 µs, respectively. In order to obtain new scintillators with high light output and high effective atomic number (Zeff), we performed anion-substitution for Cs2HfCl6 (CHC) scintillator, and then, we succeeded in growing Cs2HfI6 (CHI) single crystalline scintillator. It had Zeff of 58, which is the same as that of CHC, and had high light output of ∼70,000 photons/MeV with 700 nm emission. However, its scintillation decay time of ∼2.5 µs was slow for practical use as gamma-ray monitor. In this study, we performed Ce3+/Eu2+ doping to Hf4+ site to improve decay time of CHI, introducing the fast 5d-4f luminescence. Ce:CHI and Eu:CHI single crystals were finally obtained by the vertical Bridgman-Stockbarger method. The luminescence spectra of the Ce:CHI and Eu:CHI were very similar to that of the non-doped CHI, which would mean that no 5d-4f luminescence of Ce3+/Eu2+ was observed. The measured light output and decay time of Ce:CHI were ∼48,000 photon/MeV and 2.3 ± 0.1 µs, respectively. As for Eu:CHI, light output and decay time were ∼69,000 photon/MeV and 2.8 ± 0.1 µs, respectively.