Properties of the perovskites, SrMn1−xFexO3−δ (x=1/3, 1/2, 2/3)

Properties of the n=3 Ruddlesden–Popper Phases Sr4Mn3−xFexO10−δ (x=1, 1.5, 2)

“…6 and 7 look very similar to the spectra previously observed for the n"2 and n"R Ruddlesden}Popper systems (18,19). Also the hyper"ne interaction parameters are similar.…”

“…However there is one major di!erence, in contrast to the measured relative spectral areas in the other systems. In the present case, the relative amount of the two iron species (Area in Table 4) is temperature independent, and surprisingly enough also (18,19). This behavior is consistent with the observations in the other Ruddlesden}Popper systems, in which the Fe ions &&dispro-portionate'' into two sites, each with a fractional valence (18,19).…”

“…In the present case, the relative amount of the two iron species (Area in Table 4) is temperature independent, and surprisingly enough also (18,19). This behavior is consistent with the observations in the other Ruddlesden}Popper systems, in which the Fe ions &&dispro-portionate'' into two sites, each with a fractional valence (18,19). Here the term &&disproportionation'' refers to a generalization of 2Fe>PFe>#Fe> to 2Fe>PFe>C #Fe>B.…”

“…Thus the formal Fe valence appears to remain close to Fe> in these Sr Mn \V Fe V O \B materials. It must be emphasized however that previous work within our group has shown Fe}K edge XAS to be rather insensitive to partial Fevalence disproportionation (18,19). In general the Fe}K main edges have a less well-de"ned peak and more intensity in features both below and above the main peak as compared to the Mn}K spectra discussed above.…”

“…The Sr Mn FeO \B compound shows an even stronger enhancement of the a1 feature. Indeed Fe substitution into 113 and 327 manganites has consistently been shown to induce similar (albeit somewhat smaller) a1-feature enhancements (18,19). Again based on the above a1 assignment, this would imply a Fe substitution-induced enhancement of transitions into the majority-spin e "nal states.…”