Mössbauer Study of Pentavalent Iron Stabilized by Oxide Matrices

Samples of K3MnO4, V2O5 and K2RuO4 containing small quantities of 57Fe were prepared and the Mössbauer effect was measured at various temperatures. A single broadened line of the room temperature spectrum of K3MnO4 with an isomer shift of −0.292(1) mm/s (relative to sodium nitroprusside) was ascribed to the pentavalent iron ion in a tetrahedral coordination. A similar line (δ = −0.30(1) mm/s) was observed in the spectrum of V2O5. Two distinct states of Fe5+, the lines of which have isomer shifts of −0.38(1) and −0.11(1) mm/s, were formed in K2RuO4. They were not stable and disproportionated to Fe6+ and Fe3+.