Defect chemical analysis of the electronic conductivity of strontium-substituted lanthanum ferrite
Abstract The electronic conductivity of La 0.4 Sr 0.6 FeO 3− δ is studied in the oxygen partial pressure range 10 −5 ≤ p O 2 /atm≤1 at temperatures 100≤ T /°C≤900. The oxygen partial pressure dependence of the electronic conductivity in the p O 2 range under investigation shows a predominantly p-type character. Combination of the p O 2 dependences of the oxygen nonstoichiometry δ and the electronic conductivity σ at constant temperatures 600≤ T /°C≤900 indicates a significant decrease of σ with increasing δ . Concentrations of electronic defects are calculated from experimental data of the oxygen nonstoichiometry via a point defect model and applied to modelling of σ as a function of δ . The mobility of holes is estimated from the electronic conductivity and the calculated charge carrier concentrations as a function of oxygen nonstoichiometry. At constant p O 2 , the electronic conductivity is thermally activated at T p O 2 range 10 −4 ≤ p O 2 /atm≤10 −2 where significant oxygen deficit occurs. The temperature dependence of the electronic conductivity of La 0.4 Sr 0.6 FeO 3− δ was combined with results of the temperature dependence of the oxygen nonstoichiometry. Thus, activation energies for electronic conduction at constant oxygen content were obtained for the high temperature region ( T >300 °C) which are in agreement with isobaric activation energies of the electronic conductivity at low temperatures ( T