Oxygen partial pressure dependence of in situ X-ray absorption spectroscopy at the Co and Fe K edges for (La0.6Sr0.4)(Co0.2Fe0.8)O3−δ

The oxygen partial pressure (P(O2)) dependence of in situ X-ray absorption spectroscopy (XAS) at the Co and Fe K edges was measured simultaneously and continuously at 900 and 1000 K. These experiments, which were performed during reduction, changing P(O2) from 1 to 10−4 atm, were used to investigate each valence related to Co and Fe in (La0.6Sr0.4)(Co0.2Fe0.8)O3−δ (LSCF). The absorption edge shift of the Co K edge was more than twice that of the Fe K edge at 1000 K during reduction. For quantitative analysis, X-ray absorption near-edge structure spectroscopy was carried out at the Co and Fe K edges; the results indicated that the Co valence decreased more easily than the Fe valence; that is, the oxygen preferentially left from the oxygen sites around Co.