Spectroscopy of Light Sensitive Defect/Impurity Centers in Photorefractive BaTiO3

Control and optimization of the behavior of photorefractive crystals requires first, a thorough understanding of the nature (charge state, local symmetry, and electronic structure) of the defects/impurities present in these materials, and of their interaction with light.1,2,3 Toward this end, we have carried out electron paramagnetic resonance (EPR), photo-EPR, and optical absorption measurements on a variety of BaTiO3 samples doped with transition metal ions. These crystals were grown by top-seeded solution growth from a melt with an excess of TiO2.