Luminescence of the System (Y, Gd, Tb)2, SiO5 :Eu3+

Oxyorthosilicates of the system (Y. Gd, Tb)2SiO5:Eu3+ crystallize in dependence on the Y:Gd+ Tb ratio in the X1 or X2 type. In cathodoluminescence an energy transfer from the hole trap Tb3+ to the electron trap Eu3+ is working for materials of X2 type up to medium Tb3+ concentrations. However, due to the reduced hole capture cross section of Tb3+ the energy transfer is hampered for the X1, series. In photoluminescence a meaningful energy transfer Tb3+ → Eu3+ is only present for high Tb3+ concentrations, working in this case due to the mobility of the excitation energy in the Tb3+ sublattice in the X1, as well as the X2, type. The mechanism of energy transfer in cathodo- and photoluminescence is discussed.