Electronic band modification for faster and brighter Ce,Mg:Lu3-xYxAl5O12 ceramic scintillators

Ce,Mg:LuYAG transparent ceramics were successfully fabricated by the solid state reaction method. The results of x-ray diffraction, photoluminescence, light yield, scintillation decay and thermoluminescence are analyzed to provide better understanding of the influence of the Y3+ admixture in LuAG on the lattice structure, electronic band structure, energy-level structure of Ce3+ centers and scintillation properties. The lattice parameter of Ce,Mg:LuYAG ceramics shows a linear growth with the increasing Y content, which is in agreement with Vegard's law. Reducing the Lu-to-Y ratio in the LuYAG matrix, the Ce3+ 5d(1) energy level shifts to a lower energy, the forbidden gap becomes narrower and the electron traps become shallower. Furthermore, the increase of light yield and accelerated slow scintillation component are found with increasing Y admixture. After optimization, the light yield of Ce,Mg:Lu0.5Y2.5Al5O12 ceramics is achieved to 24,500 ph/MeV with 1 mu s shaping time, which is 40% higher than the value in the Y-free Ce,Mg:LuAG ceramic sample.