DEFECT AND LIGHT INDUCED ABSORPTION, LUMINESCENCE AND DIELECTRIC PROPERTIES IN SBN:CERIUM

Abstract

Congruent Sr0.61Ba0.39Nb2O6 crystals with different amounts of Cerium doping grown in the crystal growth laboratory of the University of Osnabrck were investigated with dielectric, luminescence and Fourier spectroscopic techniques. In the IR region absorption measurements show three different defect induced transitions, the first of which belongs to an OH-absorption (approximate to 3495 cm(-1), MIR), the second to Ce3+ spin orbit split 4f states (approximate to 2200 cm(-1), FIR) and the third in reduced Sr0.61Ba0.39Nb2O6 a broadband polaronic absorption at about 1.6 mu m (NIR). The light induced (Ar+-laser, 514 nm) change of these absorptions at room temperature and their variation down to low temperature are the topic of this paper. In addition, we present our results on dielectric measurements and luminescence in Sr0.61Ba0.39Nb2O6. At least three different electronic levels are needed in order to explain the effects induced by visible light (Ar+-laser) in Sr0.61Ba0.39Nb2O6:Ce.