Fig. 1. Crystalline structure diagram of PrBa_0.8Ca_0.2Co₂O_5+δ

Fig. 2. XRD patterns of different Fe content (a) and different element doped samples fired (b) at 1 050 °C for 12 h in air

Fig. 3. SEM images of the morphology of PBCCFe5 powders fired at 1 050 °C for 12 h in air (a) and the cross-section of a single cell with a PBCCFe5 air electrode sintered at 950 °C for 4 h in air (b)

Fig. 4. Variations of electrical conductivity (a) and thermal expansion coefficient (b) of samples with different Fe content in ambient air

Fig. 5. Electrochemical impedance spectroscopy of a PBCCFe5 electrode tested at 550~700 °C (a) and variation trends of R_pwith different Fe doped content (b)

Fig. 6. I-V-P curves of a PBCCFe5 single cell tested from 700 °C to 550 °C (a) and comparison of max power densities with different Fe doped content (b)

Fig. 7. I-V-P curves of a PBCCFe50 single cell tested from 700 °C to 550 °C

Fig. 8. Conductivity results of different doped elements (a), I-V-P curves of PBCCAl5 (b) and PBCCNi5 (c) single cells tested from 700 °C to 550 °C and comparison of max power densities (d)