Oxygen non-stoichiometry, defect equilibrium and electrical properties of La0.8Sr0.2ScyMn1-yO3±δ (y = 0.2, 0.3, 0.4)

Abstract

Non-stoichiometric variation of oxygen content in La0.8Sr0.2 ScyMn1-yO3±δ (y = 0.2, 0.3, 0.4) were determined by means of coulometric titration as a function of oxygen partial pressure p(O2) and temperature. La0.8Sr0.2ScyMn1-yO3±δ oxides shows oxygen excess and oxygen deficient composition depending on p(O2). Random defect model was constructed based on the experimental oxygen non-stoichiometry. The non-stoichiometric variation of oxygen content of La0.8Sr0.2ScyMn1-yO3±δ can be explained by the defect equilibrium model. Thermodynamic quantities such as partial molar enthalpy and partial molar entropy were calculated using Gibbs-Hemholtz equation. Electrical conductivity measurements were performed as a function of oxygen partial pressure and temperature, which shows a typical p-type behavior.