Electrical conductivity in uranium doped, modified lead zirconate pyroelectric ceramics

Abstract

A number of ceramic compositions in the PbZrO₃-Pb₂FeNbO₆-PbTiO₃ system have been developed for use in pyroelectric ‘point-detectors’. It has been found that it is highly desirable for the pyroelectric ceramic to possess a controllable electrical resistivity in the range of 10⁹ to 10¹¹Ωm to allow the detector element's electrical time constant to be simply determined.

The effects of the addition of up to 1 mole % UO₃ and the inclusion of up to 3 mole % excess PbO during the fabrication of selected compositions in the PbZrO₃ - Pb₂FeNbO₆ - PbTiO₃ ceramic system were investigated. Measurements of electrical resistivity, pyroelectric coefficient, dielectric constant and loss, and grain size were carried out. Two distinct activation energies were measured for the conduction process. Evidence suggests that both electron and hole conduction may be observed, depending upon the uranium concentration and PbO excess. Significant reductions in dielectric constant and loss, brought about by uranium doping, are interpreted in terms of domain - defect interactions.