Electronic conduction mechanism and defect chemical model of LaNi0.4Fe0.6O3−

In order to elucidate the electronic conduction mechanism and defect chemical model of LaNi 0.4 Fe 0.6 O 3 − δ at high temperatures, electrical conductivity ( σ ), Seebeck coefficient ( S ), and oxygen vacancy concentration ( δ ) of LaNi 0.4 Fe 0.6 O 3 − δ were measured as a function of oxygen partial pressure ( p (O 2 )) and temperature. Relatively large σ and small positive S values are observed, which indicates the contribution of ionic conduction is negligibly small to thermoelectric power and the major electronic carrier is a hole. From the analysis of σ and S , it is expected that the LaNi 0.4 Fe 0.6 O 3 − δ has small polaron hopping conduction mechanism where an electron is localized on the Fe. The slope of δ vs p (O 2 ) shows a minimum value near the stoichiometric composition and the δ increases as p (O 2 ) reduces and temperature increases. The relationship between δ vs. log p (O 2 ) is analyzed by a localized electron model and the behavior of the oxygen nonstoichiometry of LaNi 0.4 Fe 0.6 O 3 − δ can be explained.