Effect of Si4+ co-doping on luminescence and scintillation properties of Lu3Al5O12:Ce,Ca epitaxial garnet films

The single crystalline Lu3Al5O12: Ce3+0.6%,Ca2+0.6% garnet films co-doped with Si4+ ions were prepared by liquid phase epitaxy technique and their optical, luminescence, and scintillation properties were studied. The Ca co-doping into the Lu3Al5O12:Ce films resulted in a drastic acceleration of decay kinetics and decreased light yield due to the oxidization of Ce3+ into Ce4+ ions. The Si4+ co-doping regenerated the Ce3+ ions by virtue of charge compensation between Ca2+ and Si4+ ions. The Ce valence changes were evidenced from the optical, photoluminescence and scintillation studies. Significant differences between the photoluminescence and scintillation properties were observed in Si + Ca co-doped samples. The influence of Si co-doping and the effect of Ce3+-to-Ce4+ ratio on the scintillation properties of Lu3Al5O12:Ce epitaxial garnet films is discussed.