Processing & properties La(sub 1-x)A(sub x)Co(sub 1-y)Fe(sub y)O(sub 3)(A = Sr, Ca) perovskites

摘要

Selected compositions within the system La(sub 1-x)A(sub x)Co(sub 1-y)Fe(sub y)O(sub 3-(delta))(A = Sr, Ca) were prepared by combustion synthesis and characterized by XRD, TGA, electrical conductivity, and oxygen permeation measurements. Substantial weight loss (due to loss of lattice oxygen) was observed in some compositions at high temperatures. For Sr containing materials, this weight loss increased with increasing Sr content. A substantial decrease in electronic conductivity was observed at high temperatures in Sr doped materials; this decrease was related to the decreased oxygen stoichiometry at these temperatures. In Sr doped compositions, oxygen flux increased with increasing Sr content. Calculated values of ionic conductivity were greater than the conductivity of yttria stabilized zirconia. Substitution of Ca for Sr resulted in substantially lower fluxes.