Microstructure, luminescence and thermoluminescence of laser-sintered polycrystalline ceramic YAG:Ce scintillators

Y3Al5O12:Ce (YAG:Ce) polycrystalline ceramics with 0.1 and 0.3 mol% Ce substituting for Y were fabricated by laser sintering and characterized in their microstructure, luminescence, thermoluminescence and scintillation in comparison to a single crystal. The polycrystalline ceramics had cubic single crystallographic phase and relative densities of 97 +/- 1 and 99 +/- 1% for the 0.1 and 0.3 mol% Ce concentrations, respectively. The combined results of attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy and photoluminescence measurements showed the polycrystalline ceramics fabricated by laser sintering to contain a higher level of structural disorder than the single crystal. The consequent broadening of the luminescence bands caused enhanced self-absorption in the polycrystalline ceramics. Radioluminescence (RL) under X-ray excitation, optical transmission and photoluminescence measurements revealed the presence of numerous types of point defects, including F centers, F+ centers/perturbed F+ centers and YAl anti-sites. A detailed investigation of the thermoluminescence of YAG:Ce was executed using different methods and a complex behavior deviating from the first order kinetics mechanism was observed. The scintillation response of the polycrystalline ceramics was evaluated under low energy gamma-ray irradiation.