The Intermediate Role of Gd3+ in the Energy Transfer from a Sensitizer to an Activator (Especially Tb3+)

Energy transfer from a sensitizer to an activator via Gd 3+ ions is discussed. This is done for the Bi 3+ → Dy 3+ and Sb 3+ → Dy 3+ transfer in , and for the Bi 3+ → Tb 3+ transfer in . The phosphor shows Tb 3+ luminescence with a quantum efficiency of 80% for excitation of Bi 3+ . After excitation of Bi 3+ , energy transfer takes place to Gd 3+ ions. Then the energy may migrate from one Gd 3+ to another until energy transfer from Gd 3+ to Tb 3+ occurs. Compared to the energy transfer in other sensitized Tb 3+ phosphors, this process has a high efficiency at relatively low activator concentrations. The energy transfer from Bi 3+ to Gd 3+ and between Gd 3+ ions mutually has been investigated for . For energy transfer between Gd 3+ ions is observed. The quantum efficiency of the Gd 3+ luminescence for Bi 3+ excitation of amounts to 75% and decreases for increasing Gd concentrations.