Optical and EPR characterization of point defects in bismuth-doped CdWO4 crystals

Abstract We suggest that the 550-nm “yellow” emission in CdWO4 is due to Bi3+ ions substituting for Cd2+ ions. The absorption band corresponding to this emission has a peak near 350 nm. This yellow emission was only observed in crystals that contained bismuth impurities. Electron paramagnetic resonace has identified two new centers in X-ray irradiated bismuth-doped CdWO4. One center is electron-like and is suggested to be a Bi2+ ion located on a Cd2+ site. The other center is assigned to a hole trapped on an oxygen ion adjacent to a Nb5+ ion substituting for a W6+ ion.