Cathodo- and Photoluminescence in Rare Earth Activated Garnets of Type Ca3M2Ge3–xSixO12 (M = Al, Ga, Sc, Y)

By activation of the garnet host lattices Ca3M2Ge3–xSixO12 (M = Al, Ga, Sc, Y) with the series of trivalent rare earths a strong cathodo- and photoluminescence is obtained for Ln3+ = Tb. There are dodecahedral and octahedral sites available for the activator. The optical properties show a strong dependence on the coordination number and the distances between the activator ions as well as on the lattice defects. The influence of the M ion and the silicium content on these parameters is studied and discussed.