Crystal growth and luminescence characterizations of halide scintillators K2LaBr5:Eu2+.

• K 2 LaBr 5 :Eu2+ single crystal was obtained successfully by vertical Bridgman method without flux for the first time. • The luminescence phenomenon of K 2 LaBr 5 :Eu2+ was studied. • The optical transmission of K 2 LaBr 5 :Eu2+ single crystal was presented and the bandgap was estimated according to Tauc and Menth's law. • For the first time, the decay time of the heterovalently doped K 2 LaBr 5 :Eu2+ single crystal under gamma rays is nanoseconds. Recent researches have shown that Eu2+ ion heterovalently doped rare earth halide scintillators attract the attention of researchers. In this paper, the transparent K 2 LaBr 5 scintillation crystals of centimeter size doped with heterovalent Eu2+ were successfully grow by the vertical Bridgman technique. X-ray powder diffraction analysis shows that the crystal has an orthonormal structure with space group Pnma(62). A small amount of Eu2+ doping does not change the internal structure of the crystal. The transmittance, the UV–visible excited spectrum and emission spectrum, X-ray excited luminescence spectrum, Photoluminescence decay time and scintillation pulse decay time have been measured at room temperature. The results show that the crystal has strong luminescence intensity, and the maximum emission peak is about 430 nm. The photoluminescence decay time of K 2 LaBr 5 :xmol.%Eu2+(x = 0.5, 1, 2) are 5.56 μs, 5.67 μs and 7.03 μs, respectively. The decay time of K 2 LaBr 5 :Eu2+ crystal under 137Cs 662 keV radiation is nanosecond, indicating that the K 2 LaBr 5 :Eu2+ crystal has fast decay characteristics and excellent time resolution performance. [ABSTRACT FROM AUTHOR]