On the Quenching Mechanism of Ce, Tb Luminescence and Scintillation in Compositionally Disordered (Gd, Y, Yb) 3 Al 2 Ga 3 O 12 Garnet Ceramics.

Two series of (Gd, Y, Yb)₃Al₂Ga₃O₁₂ quintuple compounds with a garnet structure and solely doped with Ce and Tb were prepared in the form of ceramics by sintering in oxygen at 1600 °C for two hours and studied for the interaction of activator ions with ytterbium ions entering the matrix. It was shown that the photoluminescence and scintillation of Ce³⁺ ions are completely suppressed, predominantly by tunneling ionization through the charge transfer state (CTS) of the Ce⁴⁺-Yb²⁺ ions. The photoluminescence of Tb³⁺ ions is quenched in the presence of ytterbium, but not completely due to the poor resonance conditions of Tb³⁺ intraconfiguration transitions and the CTS of the single Yb³⁺ and the CTS of Ce⁴⁺-Yb²⁺ ions. The scintillation in the visible range of both Ce³⁺- and Tb³⁺-doped samples is intensely quenched as well, which indicates strong competition from Yb³⁺ ions to activators in interaction with the Gd substrate. [ABSTRACT FROM AUTHOR]