Effect of reducing $Lu^{3+}$ content on the fabrication and scintillation properties of non-stoichiometric $Lu_{3}−_{x}Al_5O_{12}$:Ce ceramics

$Lu_{3}−_{x}Al_5O_{12}$:Ce optical ceramics ($Lu_3−_{x}AG:Ce,$ x = 1, 2, 3 and 4 at.%, respectively) with $Lu^{3+}$ compositions ranging from 1 to 4 at.% below stoichiometry content were fabricated by solid state reaction method and further optimized by an air-annealing process. The effect of $Lu^{3+}$ deficiency on the optical, luminescence and scintillation properties of such a non-stoichiometric $Lu_3−_{x}Al_5O_{12}$:Ce ceramics was investigated. Significant influence in the material densification was found leading to strong changes in the transparency, radioluminescence (RL) and scintillation response of these ceramics. Within the range of 1–4 at.% $Lu^{3+}$ deficiency, LuAl antisite defects were suppressed effectively and the $Lu_3−_{x}AG:Ce$ ceramics displayed an extremely high RL intensity which reaches ∼4 times higher than that of the latest commercial LuAG:Ce single crystals while its transparency deteriorated. The microstructure, presence of foreign phases and charge traps acting in scintillation mechanism were also characterized by means of SEM, back scattered electron imaging and thermoluminescence techniques, respectively.