Light-induced charge transport properties of Sr_061Ba_039Nb_2O_6:Ce crystals

Measurements of absorption, photoconductivity, and dark conductivity and of light-induced absorption changes in photorefractive Sr0.61Ba0.39Nb2O6:Ce crystals with Ce concentrations from 0.025 wt% to 1.6 wt% are carried out for different light wavelengths, intensities, and polarizations. The experimental findings are interpreted alternatively by the two-center or by the three-valence model. The results yield that the concentrations of the deep and of the more shallow photorefractive levels increase linearly with the Ce concentration and show that for SBN:Ce the two-center model is probably more appropriate.