Electronic, Structural, and Magnetic Properties of ⁵⁷Fe Atoms Created by ⁵⁷ Co Electron Capture Decay in CoF₂ and in CoCl₂− and FeCl₂− Bispyridine Complexes

Abstract

A comparative investigation of the 67Fe absorption and emission spectroscopy data in hosts of CoFz, CoC1,-2py, and FeCI,-2py is reported in both the paramagnetic and antiferromagnetic phases of these compounds. The electron capture decay products are observed to coexist in the Fez+ and Fe3+ ionic configurations in CoF,, while only the Fez+ charge state is stabilized in FeC1,-2py and CoC1,-2py hosts. Distributions of hyperfine interactions are observed in the complex ligand compounds FeCIz-2py and CoC1,-2py, whereas there is no indication for such effects in the monoatomic ligand compound CoF,. This indicates unique unperturbed substitutional rest sites in CoF,, whereas in the other hosts, part of the decay products are observed in a distribution of defect sites.Une etude comparative des spectres Miissbauer de 57Fe en kmission et en absorption dans let matrices CoF,, CoC1,-2py et FeCL-2py a 6th realisee B la fois dans les phases paramagnetique es ordonnee de ces composbs. Dans CoF,, les atomes de 57Fe Crees par capture Blectronique coexistent dans les configurations Fez+ et Fe3+, tandis que dans FeClZ-2py et CoC1,-2py, seul 1'6tat divalent Fez+ est observe. Dans les composes B ligands complexes FeC1,-2py et CoCI,-Spy, une distribution de parametres hyperfins est mesurke; par contre, dans le compose B ligand monoatomique CoF,, il n'existe aucun argument en faveur d'une telle distribution. Les rbsultats suggkrent que, dans CoF,, les atomes nuclkoghes resident dans des sites de substitution uniques non perturbks, tandis que dans les autres composes, les produits de decroissance presentent une distribution de dkfauts P tructnraux.

Mössbauer Spectroscopy in Actinide Research

“…It is in principle possible to infer information on the lattice location and defect configuration of the recoil nuclei from emission spectroscopy [38,103]. In practice, this is difficult because of the broad hfi distribution and of our inability to correlate theoretically the hfi parameters with lattice sites and configurations.…”