Temperature Dependency of Emission Characteristics of Eu3+ in Glasses

The temperature dependency of the total emission intensity and the decay time cone stant of the 5D0 level after the CTB excitation was investigated in various glasses con taming Eu3+, and nonradiative process of Eu3+ center was discussed in connection with the effect of host composition. The broad UV excitation band induced by Eu3+ was considered to be ascribed to the charge transfer states of Eu3+-anion complex. This band was found to displace toward higher energy in the series silicate->germanate->borate-glass and , comparing the effect of alkali ions, K+>Na+>Li+ respectively. In a series of borate glasses , the minimum in the change of the max appeared at around 85 mol% B23. On the basis of correlation of the QT with the max, it may be noted that the tem perature dependency of the emission characteristics increases as the interaction of the environment with Eu3+ increases. Borate glasses, however, showed much greater tempera ture dependency than germanate glass in spite of a little difference on the max. This may be attributed to larger phonon energy in borate glasses. It was found that the decrease of the emission intensity began at lower temperature than the decrease of the decay time constant. This result indicates that the nonradiative transitions occur at the transition process from the CTB directly excited, through which the excitation of the emitting 5D0 level is achieved . The activation energy for the thermal quenching was in the range of 14001700cm-1 . Comparing these values and the max with the results on LaAl3 , the model which excited ions are coupled with the ground states via the CTB may be reasonably received as the mechanism on the nonradiative process of Eu3+ in glasses. [Received December 1, 1973