The oxygen non-stoichiometry and electrical conductivity of La0.7Sr0.3Cu0.2Fe0.8O3−δ

Abstract

The oxygen stoichiometry, conductivity, and thermal expansion behavior of lanthanum strontium copper iron oxide (La_0.7Sr_0.3Cu_0.2Fe_0.8O_3−δ) have been investigated because of its potential application as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). The relative oxygen non-stoichiometry of La_0.7Sr_0.3Cu_0.2Fe_0.8O_3−δ as a function of pO₂ has been obtained by solid-state coulometric titration at 800 ≤ T ≤ 1000 °C and at 10⁻¹³ ≤ pO₂ ≤ 0.5 atm. Two discontinuities in the pO₂ dependence of the stoichiometry and unexpected hysteresis effects were observed at the temperatures measured. The electrical conductivity behavior as a function of pO₂ and temperature was determined and related to the oxygen non-stoichiometry.