Dielectric inspection of BaZr0.2Ti0.8O3 ceramics under bias electric field: A survey of polar nano-regions

The structure and dielectric properties of BaZr0.2Ti0.8O3 ceramics prepared by citrate method were investigated. Structural analysis of the ceramics indicated a cubic perovskite structure and a fine-grained (about 250 nm) microstructure. The ceramics displayed a frequency dispersion of the dielectric loss and a slim polarization versus electric field (P–E) hysteresis loop. These results were related to the existence of polar nano-regions (PNRs) embedded in the non-polar matrix of the ceramics. The nonlinear dielectric properties under bias electric field were found to be dependent on holding time of applied bias field. The phenomenon was qualitatively explained with polarization reorientation of PNRs under the bias field. Fitting the dielectric constants under the bias field to a multipolarization mechanism model resolved the contribution of PNRs from the overall dielectric response. From the fitting, the polarization and size of PNRs in the ceramics were determined to be around 0.4 μC/cm2 and 9 nm, respectively.