Cathodo- and Photoluminescence in the Tb3+ Activated Garnets of Type Cd3−xCaxAl2Ge3O12

The Cd garnet Cd3Al2Ge3O12 activated with Tb3+ is an efficient green emitting phosphor. Under cathode ray excitation its efficiency is about 75% of that of Y3Al5O12:Tb3+ (P 53); the corresponding value for UV excitation is about 70%. The high efficiency is ascribed to an energy transfer between defect centres of the host and the activator, considerably reduced with increasing Ca content in the series Cd3−xCaxAl2Ge3O12:Tb3+. The luminescence properties are studied as a function of the Cd/Ca ratio.