Pb loss in Pb(Zr,Ti)O₃ ceramics observed by in situ ionic conductivity measurements

Analysis of the impedance spectra of Nb-doped Pb(Zr,Ti)O₃ (PZT) embedded capacitors revealed that the ionic conductivity increased monotonically during annealing at 700 °C. Furthermore, the rate of increase was lowered by a reduction in the ambient pO₂. The results could be explained by a model in which oxygen vacancies are generated as a consequence of Pb evaporation from the PZT. At 700 °C, this process is most likely limited by surface kinetics rather than Pb bulk diffusion. It was shown that the Pb loss could be completely recovered by annealing in a high activity Pb source with a commensurate reduction in oxygen vacancy concentration. The electronic conductivity was predominantly p-type and was relatively unaffected by the Pb loss throughout the course of the experiment.