Effect of Doping Level x in Ln_(1-x)M_xFeO_(3-δ) SOFC Cathodes

摘要

A family of iron perovskites with the general formula AFeO_(3-δ) (A = Ln_(1-x)M_x; Ln = La, Nd and/or Pr; M = Sr or/and Ca) has been prepared keeping fixed the A cation radius () and cation size mismatch (σ~2(r_A)) to isolate the effect of divalent dopant concentration (x) from the A cation steric effects. The electrochemical behaviour of these compounds for their application as SOFC cathodes was evaluated by using ac impedance spectroscopy and I-V curve measurement over three electrodes electrolyte supported cells processed under identical conditions. In contrast with the bulk behaviour, trends are more difficult to observe due to microstructural effects, but results seem to indicate that the doping level x does not influence in a significant way the electrochemical performance of iron perovskites with identical and σ~2(r_A).