Light sensitive paramagnetic defects in BaTiO3

Abstract
Many paramagnetic defects were identified in nominally undoped BaTiO3; among them for the first time: O trapped holes and Cr5+. All defects can change their charge states under illumination. They thus can take part in the photorefractive effect of BaTiO3. By monitoring the ESR defect concentrations in dependence of light wavelengths several charge conversion thresholds were identified.