OPTICAL STUDY OF EU-3+ LUMINESCENCE IN LITHIUM RARE-EARTH BORATES, LI6GD(BO3)3, LI6Y(BO3)3

The luminescence of Eu3+ doped rare earth lithium double borates, Li6RE(BO3)3, RE = Gd and Y, was studied at 77 K under UV and dye laser excitation. The 7F(J) (J = 0-4) energy level schemes obtained from luminescence spectra are similar in both matrices. The complete lifting of degeneracy of 7F(J) levels and the absence of selection rules is in accordance with low point symmetry of the RE site, C1. The splitting of the 7F(J) levels is small indicating very weak crystal-field (CF) effects in Li6RE(BO3)3 matrices. The correlation of the strength of the CF effect to the high concentration quenching limit of Eu3+ emission in Li6RE(BO3)3 is discussed.