Photoluminescence study of cadmium tungstate crystals

The steady-state luminescence properties of bismuth-doped and undoped CdWO4 crystals have been investigated at temperatures ranging from 4.8 to 320 K. Three different excitation wavelengths (313, 325 and 351 nm) were used. Th e intrinsic "blue" emission band (near 490 nm at room temperature) was obse rved in both undoped and Bi-doped CdWO4 crystals when pumped with above-ban d-gap light. When excited with 351-nm below-band-gap light at room temperat ure, the undoped sample exhibited no significant emission while the Bi-dope d sample exhibited a bright yellow emission near 560 nm due to transitions within the Bi3+ ions. The peak position and integrated intensity of both em ission bands were monitored as a function of temperature from 5 to 320 K. A lso, the polarization dependence was determined for the Bi-related emission and the intrinsic emission in CdWO4. The yellow PL from Bi3+ ions and its associated absorption band peaking near 350 nm were found to be partially p olarized (i.e. enhanced when the electric field is oriented perpendicular t o the b-axis of the crystal). (C) 2000 Elsevier Science Ltd. All rights res erved.