Research on Efficient Fast Scintillators: Evidence and X‐Ray Absorption Near Edge Spectroscopy Characterization of Ce 4+ in Ce 3+ , Mg 2+ ‐Co‐Doped Gd 3 Al 2 Ga 3 O 12 Garnet Crystal
Résumé
Herein, the most advanced oxide scintillator Ce3+, Mg2+‐co‐doped Gd3Al2Ga3O12 (GAGG) garnet host, grown using the Czochralski method is reported. The charge transfer absorption band in UV, such as in other Ce3+, Mg2+‐co‐doped oxides, reveals the creation of stable Ce4+ oxidation state, in addition to the usual Ce3+ one, admitted as responsible of the scintillation mechanism improvement displayed by this garnet. Strangely, the confirmation of quantitative values of Ce4+ concentration has never been done, and the goal is mainly focused on the presence of Ce4+ and the evaluation of the Ce3+/Ce4+ ratio measured by X‐ray absorption near edge spectroscopy (XANES) spectroscopy at the Ce LIII threshold of the European Synchrotron Radiation Facility (ESRF). This result is compared with those obtained for Ce3+, Mg2+‐co‐doped Lu3Al5O12 (LuAG) and, also, in garnets without any Mg2+ ions such as Ce3+‐doped GAGG, Ce3+‐doped LuAG, and Ce3+‐doped YAG. The role of Li+ ion in place of Mg2+ one is also considered in Ce3+, Li+‐co‐doped LuAG single crystal.
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