It was pointed out that doping Sr0.61Ba0.39Nb2O8 with Ce enhanced its photo-refractive properties, but that many details and microscopic properties of the associated centers and their interaction with light were insufficiently understood. Fourier spectroscopy, ranging from the ultra-violet to the far-infrared, was used to investigate the absorption spectrum and its change under intensive Ar+ laser illumination. At about 2200/cm, transitions that were due to Ce3+ spin orbit split 4f states exhibited, at low temperatures, characteristic light-induced changes which were characteristic of the Ce3+ oxidation state. A broad-band polaronic Nb4+ absorption at about 1.6 also appeared under Ar+ laser illumination at low temperatures. Light-induced charge transfer processes led to absorption changes which could be consistently explained on the basis of a simplified model which involved Ce3+/4+ centers and polaronic Nb4+ centers.

S.Kapphan, G.Greten, R.Pankrath: Materials Science Forum, 1997, 239-241, 321-4