Radiation-induced luminescence and photoluminescence properties of (K,Rb)2CuBr3 crystals synthesized by the slow cooling method

(K,Rb)2CuBr3 crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K2CuBr3, (K0.25,Rb0.75)2CuBr3, (K0.5,Rb0.5)2CuBr3, (K0.75,Rb0.25)2CuBr3, and Rb2CuBr3 were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K2CuBr3 and Rb2CuBr3. Among these samples, (K0.75, Rb0.25)2CuBr3 showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of 137Cs γ-rays (662 keV).