Effect of impurities on the formation of inclusions and γ-ray detection properties of Cs3Cu2I5 single crystal

Abstract

Cs₃Cu₂I₅ is an ideal scintillator with excellent stability, high light yield and satisfying energy resolution. However, CsI inclusions can be easily formed during its growth, which are detrimental to its scintillation properties. This study successfully obtained Cs₃Cu₂I₅ single crystal with the vertical Bridgeman method. After the zone refining of raw material CuI, the formation of CsI inclusions can be effectively restrained. The observation of the inclusions by SEM demonstrated that they grow along the vertical direction of Cs₃Cu₂I₅. The origin of CsI inclusions can be explained by the constitutional supercooling theory. After the purification of CuI, the transmission of Cs₃Cu₂I₅ is significantly improved from 60% to 90%. Meanwhile, the light yield of the as-grown single crystal is increased from 34 860 ph MeV⁻¹ to 36 695 ph MeV⁻¹, and the energy resolution is also optimized from 6.7% to 4.0%.