Thermodynamic Properties, Defect Analysis, and Electrical Conductivity of the La0.8Sr0.2ScxMn1-xO3-δ Infiltrated into YSZ Scaffolds.

La_0.8Sr_0.2Sc_xMn_1-xO_3−δ–yttria stabilized zirconia composite anodes were synthesized by infiltration and investigated as alternative anodes for intermediate solid oxide fuel cells. Non-stoichiometric variation of oxygen content and electrical conductivity in La_0.8Sr_0.2Sc_xMn_1-xO_3−δ–yttria stabilized zirconia composite was studied by high temperature coulometric titration at 923–1023 K. La_0.8Sr_0.2Sc_xMn_1-xO_3−δ shows an oxygen deficient composition depending on the oxygen partial pressure, temperature, and Sc content. A defect chemistry model is presented by taking into consideration the interaction of randomly distributed defects, Sr’_La,V _ö, O^X_O, Mn^X_Mn, Mn·_Mn and Sc^X_Mn. The proposed defect model fits well with experimental non-stoichiometric data. The interaction among the defects for vacancy formation is strongly influenced by the amount of dopant, Sc content, and temperature. The thermodynamic properties, oxidation enthalpy ΔH and entropy ΔS, were obtained from the oxygen isotherms. The electrical conductivities measured by the 4-probe method as a function of oxygen partial pressure and temperature were high enough for composite anode application. [ABSTRACT FROM AUTHOR]