Defect states in Lu3GaxAl5−xO12 crystals and powders

We study defect states in undoped and Eu3+-doped Lu3GaxAl5−xO12 (x = 0–5) garnet crystals by wavelength resolved thermally stimulated luminescence above room temperature. Eu3+ ions act not only as recombination centres but also as high temperature traps, as testified by the presence of a TSL peak at 450 °C correlated with Eu3+-doping. With increasing gallium content all glow peaks are shifted to lower temperatures. This trend is confirmed also for powder samples prepared by sol–gel technique. The observed low temperature shift of the glow peaks can be considered as a consequence of the band gap reduction following the increase of Ga3+ concentration. The comparison with the glow curve of a Ce3+-doped crystal is also shown.