M. D. Birowosuto, P. Dorenbos, K. W. Krämer and H. U. Güdel
Ce³⁺ activated LaBr_3–xI_x: High-light-yield and fast-response mixed halide scintillators
J. Appl. Phys. 103, 103517/1-6 (2008)                 

Abstract: Here, we report the scintillation properties of LaBr_3–xI_x:5%Ce³⁺ with four different compositions of x, i.e., x=0.75, 1.5, 2, and 2.25. Radioluminescence spectra reveal a shift of the emission wavelength with the LaBr₃ to LaI₃ ratio. LaBr_1.5I_1.5:5%Ce³⁺ shows the highest scintillation light yield of 58000 photons/MeV, whereas LaBr_0.75I_2.25:5%Ce³⁺ shows the fastest scintillation decay time of 12 ns under 662 keV g-ray excitation. This decay time is faster than that of 16 ns in LaBr₃:Ce³⁺. The temperature dependence of radioluminescence spectra is presented. The structures and lattice parameters of the materials were determined from powder x-ray diffraction.