Defect Chemistry of (La,Sr)MnO3

TLDR

Defect‑disorder models are derived for undoped and strontium‑doped LaMnO₃. The authors construct random‑defect and cluster‑defect models based on experimental nonstoichiometry data, considering oxygen deficit and excess regimes, and verify them against electrical‑conductivity measurements. Both models predict that strontium addition increases electron‑hole and oxygen nonstoichiometry concentrations, that cluster‑defect concentrations are significant only at very low oxygen partial pressures, and that the random‑defect model agrees well with experimental conductivity data.

Abstract

Defect‐disorder models are derived for undoped and strontium‐doped LaMnO 3 . A random‐defect model and a cluster‐defect model are both considered within the regimes that correspond to oxygen deficit and oxygen excess. The models are constructed based on the experimental nonstoichiometry data that was reported by previous researchers. According to both models, the addition of strontium leads to an increase of the concentration of electron holes and oxygen nonstoichiometry. The defect clusters that are predicted by the cluster model have a marked concentration only at very low oxygen partial pressures. Both models are verified against the electrical‐conductivity data. A good agreement between the random‐defect model and the experimental data is shown.