Study on the segregation behavior of Ce in CLYC crystals

Ce-doped Cs₂LiYCl₆ (CLYC) has widespread applications in homeland security owing to its excellent neutron/gamma discrimination ability. Ce³⁺ ions, as luminescent centers of CLYC, have a significant difference in effective ionic radius compared with Y³⁺, hinting at the severe inhomogeneous distribution of Ce³⁺ in CLYC. Still, only the relation between scintillation properties and nominal doping concentrations in CLYC crystals has been reported. The segregation behavior of Ce³⁺ ions along the ingot are still open for research. Herein, we measured the actual Ce³⁺ doping concentration along the CLYC ingot. Gamma-ray energy spectrum and powder XRD patterns of different samples were utilized to study the effects of Ce segregation on CLYC crystals. The effective segregation coefficient of Ce in CLYC crystals, k_eff = 0.22, was calculated. In most part of the ingots, the concentration of Ce³⁺ ions was lower than the nominal doping amount and rose rapidly at the tail. The scintillation properties of CLYC crystals along the ingot were affected by the distribution of Ce concentrations. This work may guide the optimization of properties for large-size CLYC crystals by modifying the distribution of Ce³⁺ ions.