Effect of Oxygen Deficiency on Mechanical and Thermomechanical Properties of Ferroic La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ

The mechanical and thermomechanical behaviors of ferroic La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ (LSCF) with different oxygen nonstoichiometries are investigated around room temperature. The effects of oxygen deficiency on these behaviors are discussed by comparing LSCFs annealed in air and Ar. X‐ray diffraction analysis and the scanning electron microscopy observation demonstrate that the formation of oxygen vacancy reduces the rhombohedral distortion in the lattice, resulting in the disappearance of ferroic domains of LSCF. The measurements of electrical conductivity at high temperatures confirm that LSCF annealed in Ar has a higher oxygen nonstoichiometry than the one annealed in air. The thermomechanical analysis and the uniaxial compression test reveal that the introduction of oxygen vacancies can significantly influence the ferroic characteristics of LSCF such as ferromagnetism and ferroelasticity, whereas the intrinsic lattice stability would remain unchanged.