A series of the additional resistor to those two elements was needed to attain a reasonably good fitting result (Figure 4a inset). These R1 and R2 should be associated with grain and grain boundary resistances. The low-frequency impedance response is fitted with CPE as a partially blocking electrode. It appeared in the wide range of measured frequency without a dielectric relaxation so that it shouldn’t be associated with the impedance element in the ceramics. Thus, this work focuses on R1 and R2