Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe2Br7†
CsCe2Br7 is a self-activated inorganic scintillator that shows promising performance, but the understanding of the important structure–property relationships is lacking. In this work, we conduct a comprehensive study on CsCe2Br7. The crystal structure of CsCe2Br7 is refined using single crystal X-ray study for the first time. It crystallizes into the orthorhombic crystal system with Pmnb space group. Its electronic structure is revealed by density functional theory (DFT) calculations. Two cerium emission centers are identified and the energy barriers related to the thermal quenching to 4f ground states of Ce3+ for these two Ce centers are evaluated. CsCe2Br7 single crystal has better light yield and energy resolution than CsCe2Cl7, but with an additional slow decay component of 1.7 μs. The existence of a deep trap with a depth of 0.9 eV in CsCe2Cl7 contributes to its higher afterglow level in comparison to that of CsCe2Br7. The most possible point defects in CsCe2Cl7 and CsCe2Br7 are proposed by considering the vapour pressure in the growth atmosphere upon melting point.
- This article is part of the themed collection: 2015 Journal of Materials Chemistry C Hot Papers