Defect Research in Cs₂LiYCl₆:Ce Crystal Scintillators

Abstract

As a promising material for dual γ-ray and neutron detection, Cs₂LiYCl₆:Ce (CLYC:Ce) has been increasingly studied and developed. In this work, CLYC:Ce is grown by two different growth methods, edge-defined film-fed growth (EFG) and the vertical Bridgman method. The phase segregation, macroscopic morphology, microscopic defects, trap-state density and radioluminescence spectra of CLYC:Ce are recorded and analyzed in detail. Because of the different raw material ratios, different second phases appear in the crystal growth process, which shows the phase segregation in the crystal. In the process of crystal growth, there are obvious cracks, bubbles, and inclusion and agglomeration phenomena in the crystal. We speculate that the reasons for these issues include inadequate mixing of the melt, the mismatch of temperature field and the excessive growth rate or excessive cooling rate. The high-quality CLYC:Ce has high carrier mobility (21.3390 cm²V⁻¹ s⁻¹) and ultra-low trap-state density (4.0681 × 10⁸ cm⁻³). According to the radioluminescence spectra, only peaks in the range of 330–450 nm exist in the whole temperature range, corresponding to Ce³⁺ component luminescence. With the increase in temperature, the emission peaks show a slight red-shift and the full width at half maximum (FWHM) generally shows an increasing trend. In the high-temperature region, the intensity of the main peak at 360 nm gradually decreases, while the intensity of the weak peak at 435 nm gradually increases.