Co-precipitation synthesis of SOFC electrode materials

A series of four compounds (LaMnO₃, La_0.70Sr_0.30MnO_3−δ, La_0.80Sr_0.20FeO_3−δ and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ) of interest as electrode materials in intermediate temperature solid oxide fuel cells have been prepared using a carbonate co-precipitation route in aqueous medium. LaMnO₃, La_0.70Sr_0.30MnO_3−δ, and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ have been obtained as a pure phase, while La_0.80Sr_0.20FeO_3−δ retained an impurity phase; fine microstructures with sub-micron sized particles can be obtained in all cases at the proper calcinations temperature, except for LaMnO₃. The precipitation yield of the single metal ions have been experimentally determined in the mother liquors and in the final powders; the results have been evaluated also in comparison with expected yields calculated from thermodynamics of the precipitation process using the software Medusa. pH higher than 7.5 are suggested to avoid ion losses for all cations. Structural and microstructural properties and TPO/TPR behaviour suggest that materials prepared via co-precipitation, especially LSCM, could be suited as electrode materials in solid oxide fuel cells.