Growth and Characterization of Mixed Halide Scintillators K 2 LaCl x Br 5− x :Ce

In this paper, it is recently discovered that mixed‐anion Cl‐Br halide scintillator K 2 LaCl x Br 5− x :Ce ( x = 0, 1, 2, 3, 4, 5) has promising performance. The mixed crystal polycrystalline materials are synthesized by high‐temperature solid‐phase method, and transparent cylindrical crystals of K 2 LaCl x Br 5− x :Ce are grown successfully by the vertical Bridgman technique. The crystals are measured by powder X‐ray diffraction, X‐ray‐induced luminescence spectra, optical transmittance, photoluminescence spectrum, photoluminescence decay time, and pulse height spectrum. Under the UV and X‐ray excitation, all of the crystal samples have the typical Ce 3+ 5d 1 → 2 F 5/2 and 5d 1 → 2 F 7/2 double peaks, emission centered between 350 and 400 nm. The photoluminescence decay time of the K 2 LaCl x Br 5− x :Ce crystal is about 30 ns under the UV excitation. The energy resolution of the crystal is generally less than 10%. As the proportion of Br ‐ ions increases, the luminescence intensity is enhanced, the photoluminescence decay speed increases, and energy resolution of these crystals is optimized. The simplicity of the growth of small‐sized crystals is promising for expanding the growth process to larger sizes.