Thermally stimulated polarization and depolarization phenomena in PbWO4 single crystals

Thermally stimulated polarization and depolarization current (TSPC and TSDC , respectively) measurements were exploited to characterize the dielectric relaxation of PbWO4 single crystals of different origin, i.e., grown by dif ferent methods and containing different amount of impurities. In addition t o the dc conduction current, measured by the TSPC runs, at least one TSDC b and was detected for the investigated specimens. Activation parameters char acterizing the polarization and conduction processes were evaluated, and th e possible nature of the related defects has been discussed. The results ob tained for nominally pure crystals show the presence of orientation polariz ation related to some permanent dipoles. In the less pure samples, in addit ion to the high-temperature interfacial polarization, a low-temperature ban d was tentatively ascribed to a space charge polarization related to the im purities. (C) 1999 American Institute of Physics. [S0021-8979(99)01914-3].