The grain size effect in dielectric diffusion and electrical conduction of PZnTe-PZT ceramics

This study investigates systematically the microstructure, dielectric diffusion and electrical conduction behavior in xPb(Zn0.5Te0.5)O-3-(1-x)Pb(Zr0.5Ti0.5)O-3 (PZnTe-PZT) ceramics. The grain size has an obvious drop in PZT and PZnTe-PZT system. EDS reveals that the Te element segregates at the grain boundary, which can inhibit grain growth during the sintering process and result in the difference of element contents between grain and grain boundary. The permittivity peak become broaden when the PZnTe add in and this phenomenon is explained by the brick-wall model, which is due to the difference in grain size. The diffusion behavior is described by the empirical expression and the W2/3M-H parameter and it shows that the co-action of the grain size effect and the doping effect influence the dielectric diffusion of PZnTe-PZT ceramics. The electrical conduction characteristics in different temperature and frequency show the difference of activation energy for ac conductivity between the PZT and the PZnTe-PZT, which are related to the grain size and the element segregation in grain boundary.