Trapping and emission centres in PbWO4 and CaWO4 crystals

The Thermally Stimulated Luminescence (TSL) properties of undoped and La3+-doped PbWO4 and CaWO4 crystals have been investigated after room temperature X-ray irradiation. The glow curves of the two tungstates display one principal peak at a very similar temperature (50°C): a common origin of the defects responsible for the trap level can thus be proposed. On the contrary, the emission spectrum of the TSL peak features one single band at 2.1 eV in the case of PbWO4, while a dominant emission at 2.85 eV is detected in CaWO4. In both La3+-doped crystals, less intense TSL signals were found with respect to undoped samples. The nature of the TSL active defects is discussed. © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.