The Effect of Cu Doping on Structural Distortions and Oxygen Vacancies in SrFeO3−δ

This study utilized XRD and Mössbauer spectroscopy to investigate the effects of copper ion doping on the structural properties and oxygen vacancies of [Formula: see text] perovskite oxides. XRD analysis confirmed that all samples maintained a single-phase perovskite structure, with a decrease in lattice constants and contraction of unit cell volumes as copper doping increased. Mössbauer spectroscopy indicated that increased copper doping caused a transition in the valence state of iron ions from [Formula: see text] to [Formula: see text], along with significant distortions in the Fe–O bond environment, reflecting local structural changes. The introduction of [Formula: see text] and [Formula: see text] ions increased oxygen vacancies, disrupting charge balance and ion radius compatibility, which in turn exacerbated lattice distortions. Iodometric titration further corroborated the rise in oxygen vacancies with higher copper content, offering important theoretical insights for advancing [Formula: see text] based materials in energy conversion and storage applications.