Electron transfer process between Ce3 +donor and Yb3 +acceptor levels in the bandgap of Y3Al5O12(YAG)

Thermoluminescence (TL) properties of Ce3 + and Yb3 + co-doped in Y3Al5O12 (YAG) were studied with the aim of determining the location of energy levels of Ce3 + and Yb2 + relative to the bottom of the conduction band (CB) and the top of the valence band (VB) of YAG. The TL glow peak at about 180 °C when heating rate β = 1°C s − 1 was assigned to electron release from Yb2 + , indicating that Yb3 + acts as an electron trap. The trap depth, which is the depth of the ground-state level of Yb2 + below the bottom of the CB, was derived from the temperatures of the maximum of the TL glow peak at different heating rates. The value is, within the experimental and theoretical uncertainties, in good agreement with that derived from the charge transfer energy. Thermoluminescence excitation spectroscopy (TLES) was used to establish the location of energy levels of Ce3 + . From the derived data the energy level diagram of YAG:Ce3 + , Yb3 + is constructed and possible electron transfer processes are discussed.