Lifetime measurements in Eu2+-doped host lattices

The decay times of the emission of Eu2+ in several host lattices have been studied. There is a wide variation in the emission wavelengths, indices of refraction and radiative lifetimes among the different host lattices. However, analysis of the decay times shows that the radial integral [5d\r\4f] varies by about 20% from the mean value of 0.81 Angstrom. The only exceptions to this are Ba2Mg(BO3)(2):Eu2+ for which an extremely long decay time of 12.6 mu s is observed, and BaSi2O5:Eu2+ for which a decay time of 3.3 mu s is measured at 4.2 K. The emission maxima are at 645 and 520 nm, respectively. Furthermore, the temperature dependence of the Eu2+ emission has been studied. In all lattices in which the emission is at longer wavelengths, it is already partly quenched at room temperature. This is in agreement with the large Stokes shifts or a low energy position of the 4f(6)5d state. (C) 1997 Elsevier Science Ltd. All rights reserved.