Structural, magnetic, and Mössbauer studies of thePrBaCuFeO5+ycompound

Interplay between Cu and Fe Valences in BaR(Cu0.5Fe0.5)2O5+δ Double Perovskites with R=Lu, Yb, Y, Eu, Sm, Nd, and Pr

“…In our earlier works the observed Component 3a was assigned to high-spin Fe>, but with the present results of the highly oxygenated samples at hand the pentavalent state seems more probable, in accordance with Ref. (4). The valence state will also be discussed further on.…”

“…The component with the smallest value for the isomer shift (Component 3, S+0.0 mm/s) is readily assigned to six-coordinated Fe in an oxidized state in accordance with results from the AF spectra and Ref. (4). As suggested above the valence is tentatively assigned to #5.…”

“…Fe> species in the intermediate spin state are not considered here, as the excess oxygen present in the phase indicates that oxidized Fe species should be found. In the earlier reports only one such component was detected (4,5,9) Table 3. The total amount of oxidized Fe in the MoK ssbauer spectra remains roughly the same, whether one is "tting the spectra using one or two components.…”

“…These were assigned to six-coordinated Fe> (9). In addition to this Pissas et al (4) reports for the Pr-based samples a prominent component of an Fe species assigned to valence state #3 based on the isomer shift and internal "eld values.…”

“…high-and/or high-¹) spectra. In the P spectra the component exhibits a rather low quadrupole splitting (4). In this work the component will be denoted as Component 1.…”