Luminescence of rare-earth ions in Ca3(BO3)2

Abstract The luminescence of the rare-earth ions Eu 3+ , Tb 3+ and Ce 3+ in Ca 3 (BO 3 ) 2 is reported. The Eu 3+ ion shows quantum efficiencies under charge-transfer excitation of 30 and 50%, depending on the preparation conditions. The Tb 3+ and the Ce 3+ ion, which have 4f n−1 5d excited states, show luminescence of medium intensity. The Stokes shift of the Ce 3+ emission amounts to about 2200 cm −1 . Whereas the Eu 3+ emission in Ca 3 (BO 3 ) 2 is quenched by the Cu + ion, the Tb 3+ emission in Ca 3 (BO 3 ) 2 can be sensitized by Cu + due to the presence of Cu + , Tb 3+ associates in the lattice.