Perovskite-based Ba0.5Sr0.5Fe1–xCuxO3–δ (BSFCO-x, x = 0–0.2) was synthesized by sol–gel self-combustion method. The crystallinity was evaluated through X-ray diffraction, besides further local structure analysis, using X-ray absorption spectroscopy (XAS) showed a cubic symmetry for x = 0.05; 0.10, which was tetragonal at higher values, x = 0.15; 0.20. XAS analysis predicted the oxidation state (OS) of Cu to be a mixture of 3+ and 2+, while Fe includes 3+ and 4+. Conversely, the OS of Fe and Cu in the octahedron site influence the number of an unpair electron that determine the magnetic properties of perovskite. In addition, the magnetization for Ba0.5Sr0.5FeO3–δ is 0.172 emu g−1, originating from the ferromagnetic ordering Fe3+(t2g3eg2)–O (2p)–Fe4+(t2g3eg1) interaction. This effect increase, due to the presence of oxygen vacancy in BSFCO-0.05, which weakens the d–p interaction of Fe-O, while the generation of higher Cu doping to increase the amount of Fe4+ leads to a decline in Cu3+. Therefore, Cu doping is confirmed to play a role in the paramagnetic–ferromagnetic transition.

中文翻译：

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BO6（B = Fe，Cu）八面体的局部结构分析与Cu掺杂Ba0.5Sr0.5FeO3-δ的磁性能相关

钙钛矿基 Ba0.5Sr0.5Fe1–xCuxO3–δ (BSFCO-x, x = 0–0.2) 通过溶胶-凝胶自燃法合成。通过 X 射线衍射评估结晶度，除了进一步的局部结构分析外，使用 X 射线吸收光谱 (XAS) 显示 x = 0.05 的立方对称性；0.10，在较高值时为四边形，x = 0.15；0.20。XAS 分析预测 Cu 的氧化态 (OS) 为 3+ 和 2+ 的混合物，而 Fe 包括 3+ 和 4+。相反，八面体位点中 Fe 和 Cu 的 OS 会影响决定钙钛矿磁性的不成对电子的数量。此外，Ba0.5Sr0.5FeO3–δ 的磁化强度为 0.172 emu g−1，源自铁磁有序 Fe3+(t2g3eg2)–O (2p)–Fe4+(t2g3eg1) 相互作用。由于 BSFCO-0.05 中存在氧空位，这种效应增加，这削弱了 Fe-O 的 d-p 相互作用，而产生更高的 Cu 掺杂以增加 Fe4+ 的数量导致 Cu3+ 的下降。因此，铜掺杂被证实在顺磁 - 铁磁转变中起作用。