INFLUENCE OF THE CRYSTAL-STRUCTURE ON THE ENERGY-TRANSFER TB3+ -] EU3+ IN OXYORTHOSILICATES LN2SIO5-TBXEUY

In the system X1-GdTbSiO5:Eu(y)3+ an energy transfer between the hole trap Tb3+ and the electron trap Eu3+ is working in cathodoluminescence. That energy transfer is less effective than in the corresponding series with X2 structure X2-YTbSiO5:Eu(y)3+, due to the marked differences between the two crystallographic positions for the Ln3+ ions in the X1 structure. In photoluminescence for X1-GdTbSiO5:Eu(y)3+ an energy transfer Tb3+ --> Eu3+ is working as well. interestingly Gd3+ does not participate, despite the fact that the Gd3+-Gd3+ distance is below the critical value for an energy migration within the Gd3+ sublattice.