ESR and TSL study of hole and electron traps in LuAG:Ce,Mg ceramic scintillator

The process of hole and electron localization in LuAG:Ce,Mg ceramics is studied by electron spin resonance (ESR) and thermally stimulated luminescence (TSL). Hole traps, which are created by UV irradiation, are detected in the form of O- centers. Mg-perturbed variants of O- centers are proposed to exist. The thermal stability of such defects is studied, proving that they are stable up to room temperature. The interaction between O- centers and shallow electron traps is studied by thermally stimulated luminescence (TSL) and phosphorescence experiments, which reveal the occurrence of an a-thermal tunneling process between trapped electrons and randomly distributed Ce centers. By correlating the TSL-derived trap parameters and temperature dependent ESR intensities, it is found that O- centers compete with Ce centers in free electron capture. (C) 2015 Elsevier B.V. All rights reserved.