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Abstract  

Sodium ferrates(IV) and (VI) were synthesized by the reaction between Fe2O3 and Na2O2 in a dry oxygen stream. The Mössbauer data for the obtained samples are presented (for Na2FeO3=0.18(2) mm/s; for Na4FeO5=–0.54(2) mm/s). It was shown that pure K2FeO4 and Cs2FeO4 can be obtained by heating Fe2O3 with apropriate alkali metal peroxides.

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Abstract  

It has been shown that cesium oxoferrate (VI) decomposes in oxygen at 500 °C giving solid CsxFeIVO2+0.5x (x1.0). The oxidation state of iron has been confirmed by Mössbauer spectroscopy data (single symmetrical resonance line with LW=0.4 (1) mm s–1 and isomr shift of 0.15 (2) mm s–1). Cesium oxoferrate (IV), CsxFeO2+0.5x, crystallizes in the face-centered cubic system with the lattice parameter of a=8.36–8.46 Å and has a crystal structure derived from perovskite.

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Abstract  

Alkaline solutions of iron compounds synthesized by anodic dissolution of metallic iron in NaOH media have been studied by Mössbauer spectroscopy. The values of the isomer shift on iron in higher oxidation states are presented. The formation of the peroxoderivatives of iron in the solutions were not fixed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. Kopelev, V. Chechersky, A. Nath, B. O, M. Larkin, J. Markert, J. Peng, and R. Greene

Abstract  

The as-prepared electron-doped system Nd2–xCexCuO4 (where x0.16) is not superconducting. It becomes superconducting only after removal of a minuscule amount of extraneous oxygen (0.02 of O per unit formula). Mössbauer effect studies were carried out for oxygenated and deoxygenated Nd2–xCexCu(57Co)O4 with x=0.14, 0.16, and 0.18. The spectra show evidence of oxygen anions attaching to the probe57Co in apical positions, to form 5- and 6-coordinated species. A conventional procedure for deoxygenation brings about little change in the Mössbauer spectra both above and below the optimal superconducting concentration; however, for x=0.16, a dramatic change is observed—a major fraction of the magnetically split five-coordinated species manifests itself as a paramagnetically relaxed doublet upon deoxygenation, which costitutes a microscopic measure of the superconducting volume fraction. This apparently anomalous behavior at x0.16, where the extraneous oxygen is more readily desorbed, may be related to an electronic and/or local structural change in the CuO2 plane.

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