Thermal, electrical, and electrochemical properties of Nd-doped Ba0.5Sr0.5 Co0.8Fe0.2O3 − δ as a cathode material for SOFC

Crystal structure, thermal expansion coefficient (TEC), electrical conductivity and AC-impedance of (Ba0.5Sr0.5) 1 − xNdxCo0.8Fe0.2O3 − δ (BSNCF; 0.10 ≤ x ≤ 0.20) were studied in relation to their potential use as intermediate temperature solid oxide fuel cell (IT-SOFC) cathode. An emphasis is made on the effect of Nd-doping on these properties. A single cubic pervoskite were observed in the X-ray diffraction (XRD) measurement. The TEC of BSNCF values were 18.7–19.7 × 10− 6 K− 1 from 30 to 800 °C. The electrical conductivity, which is the main defect of Ba0.5Sr0.5 Co0.8Fe0.2O3 − δ (BSCF), was improved by Nd-doping, e.g. the compound of x = 0.20 demonstrated a conductivity of σ = 130 S·cm− 1 at 392 °C. The AC-impedance analyses were carried out on an electrolyte supported BSNCF/ Sm0.2Ce0.8O1.9 (SDC)/Ag half-cell and a BSCF/SDC/Ag half-cell. The BSNCF cathode revealed lower polarization resistance than BSCF, e.g. at 500 °C, the values for the x = 0.20 sample and BSCF were 1.79 Ω cm2 and 4.52 Ω cm2, respectively.