The literature non-stoichiometry data for bulk defects in LaxSr1−xMnO3-δ was analyzed using a rigorous inverse-problem methodology. A solver–optimizer combination of Newton's method and the particle swarm optimizer was developed, along with a rigorous method for determining local identifiability in the comparison between defect models and experimental data. It was found that previous models, which did not account for any excess free energy for defects, cannot adequately replicate non-stoichiometry data at low temperatures. A revised model was proposed that included excess free energy due to strain field interaction between cation defects. The revised model was shown to be consistently distinguishable from the earlier model (a better fit) even when using a model structure containing fewer parameters. It was also identifiable for 10 and 20% Sr-doping. Data for activation energies and vibrational entropy for the various defect reactions was compiled.

Refinement of the Bulk Defect Model for LaxSr1−xMnO3±δ. D.S.Mebane, Y.Liu, M.Liu: Solid State Ionics, 2008, 178[39-40], 1950-7