The oxygen nonstoichiometry of La0.6Sr0.4FeO 3 - δ was measured at intermediate temperatures (773 to 1173 K) between 1 bar and the decomposition oxygen partial pressure by thermogravimetry and coulometric titration. The decomposition of the ABO3 perovskite phase was found to occur at low oxygen partial pressures (below 10 - 20 bar). Using an atmosphere-controlled high-temperature XRD setup, the rhombohedral lattice parameters were obtained between 10- 4 and 1 bar at 773 to 1173 K. A phase transition from rhombohedral to cubic might be expected to occur at high temperatures and for δ near the plateau at δ = [Sr] / 2. The lattice expansion was separated into "pure" thermal and chemically induced expansion by combining the lattice parameters with the oxygen nonstoichiometry data. The linear thermal expansion was formulated with a "pure" thermal expansion coefficient of αth = 11.052 • 10- 6 K- 1 and a chemical expansion coefficient of αchem = 1.994 • 10 - 2. The results were compared with previous data obtained for La0.6Sr0.4Co1 - yFeyO 3 - δ with y = 0.2-0.8. La0.6Sr 0.4FeO3 - δ was confirmed to show the highest thermo-chemical stability. While the chemical expansion of La 0.6Sr0.4Co1 - yFeyO 3 - δ seems little affected by the iron content, the thermal expansion coefficient was the lowest for La0.6Sr 0.4FeO3 - δ.
- Chemical expansion
- High-temperature X-ray diffractometry
- Oxygen nonstoichiometry
- Strontium doped lanthanum ferrite
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics