Thermally stimulated polarization and depolarization phenomena in PbWO4 single crystals

Abstract

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 different methods and containing different amount of impurities. In addition to the dc conduction current, measured by the TSPC runs, at least one TSDC band was detected for the investigated specimens. Activation parameters characterizing the polarization and conduction processes were evaluated, and the possible nature of the related defects has been discussed. The results obtained for nominally pure crystals show the presence of orientation polarization related to some permanent dipoles. In the less pure samples, in addition to the high-temperature interfacial polarization, a low-temperature band was tentatively ascribed to a space charge polarization related to the impurities.