Exploring the defect equilibrium and charge transport in electrode material La0.5Sr0.5Fe0.9Mo0.1O3-δ

Perovskite-type La0.5Sr0.5Fe0.9Mo0.1O3-delta synthesized via glycine nitrate combustion and sintered at 1350 degrees C was found to have an orthorhombic lattice, which transforms upon heating into a rhombohedral and then a cubic one. The oxygen content and electrical conductivity in this oxide were measured in the range of oxygen partial pressures from 10(-20) to 0.5 atm at 750-950 degrees C by coulometric titration and four-probe dc techniques, respectively. The oxygen content data were used to model the defect equilibrium in the oxide. Oxidation, charge disproportionation and electron exchange reactions between iron and molybdenum were assumed by the model to be involved in the formation of defects. The experimental data were well approximated with the model and the concentrations of charge carriers in La0.5Sr0.5Fe0.9Mo0.1O3-delta were determined to be used for the electrical conductivity analysis. The average mobility of oxygen ions and n- and p-type charge carriers was determined to be about 10(-5), 0.007, and 0.07 cm(2) V-1 s(-1) with an activation energy of 0.80 +/- 0.02, 0.34 +/- 0.01, and 0.23 +/- 0.01 eV, respectively. Comparison with La0.5Sr0.5FeO3-delta shows that 10% Mo substitution provides a substantial increase in both the concentration and mobility of n-type carriers, which results in an almost threefold increase in electron conductivity under reducing conditions, while maintaining a high level of ionic conductivity.

Automated summary

La0.5Sr0.5Fe0.9Mo0.1O3-delta, a perovskite-type oxide synthesized through combustion and sintering, has been characterized for its oxygen content and electrical conductivity. A model was used to simulate the defect equilibrium and determine the concentrations and mobilities of charge carriers in the oxide. Substituting molybdenum resulted in an increased concentration and mobility of n-type carriers, leading to improved electron conductivity.