Electrical Conductivity and Oxygen Nonstoichiometry of La[sub 0.2]Sr[sub 0.8]Fe[sub 0.55]Ti[sub 0.45]O[sub 3-δ]

The electrical conductivity of (LSFTO) was measured in the temperature range and at oxygen partial pressures of . The conductivity was measured on both increasing and decreasing to ensure that equilibrium was reached. Long equilibration times were required at intermediate oxygen partial pressures between and . The pressure dependence of the conductivity in this range differs from that previously reported for related compositions. The mobilities of the charge carriers were derived from the stoichiometry and conductivity data. The average hole and electron mobilities of LSFTO at are 0.015 and , respectively. The oxygen nonstoichiometry as a function of was determined by solid-state coulometric titration. Data were obtained in the temperature range, , and in the range, . A point defect model was used to fit the dependence of δ on . The partial molar thermodynamic quantities for oxidation were calculated and the oxygen nonstoichiometry data were related to the electrical conductivity data.