A study of Mg2+ ions effect on atoms segregation, defects formation, luminescence and scintillation properties in Ce3+ doped Gd3Al2Ga3O12 single crystals

The undoped, Mg2+ doped, Ce3+ doped as well as Mg2+:Ce3+& nbsp;codoped Gd3Al2Ga3O12 crystals were grown from the melt by the micro-pulling down method. Ce3+ and Mg2+& nbsp;ions were codoped in a wide concentration range. A study of Mg2+& nbsp;ion concentration effect on the luminescence and scintillation properties as well as segregation of atoms and defects creation processes were carried out. Mg2+& nbsp;doping in Gd3Al2Ga3O12 led to the creation of O-O(center dot)& nbsp;defects localized next to Mg2+& nbsp;sites due to charge imbalance compensation. Consequently, neutral (MgGa/Al/GdOO)(x) defects were formed. In Ce3+& nbsp;doped crystals, Mg2+& nbsp;codoping changed the valence state from Ce3+& nbsp;to Ce4+ to maintain charge neutrality. Hence, additional neutral (Ce-Gd(center dot)-Mg-Ga/Al/Gd')(x) and (Ce-Gd-MgGa/Al/GdOO)(x) defects appeared. Moreover, Mg(2+& nbsp;)induced charge imbalance in GAGG crystal might also be compensated by the formation of oxygen vacancies (V-O(center dot center dot)). The Mg2+& nbsp;ions imposed defects deteriorated the segregation of atoms. Accordingly the radial inhomogeneity of the crystals was diminished. The presence of stable Ce4+ and defects imposed by Mg2+& nbsp;ions codoping were proved by absorption, photoluminescence, and scintillation decay time analysis. Hence, Mg2+& nbsp;codoping resulted in quenching of the Ce3+& nbsp;luminescence, acceleration of scintillation response, reduction of light yield, and thermally stimulated luminescence. The mechanism explaining a strong luminescence quenching with increasing Mg2+& nbsp;ions concentration was proposed. (C)& nbsp;2022 Elsevier B.V. All rights reserved.