The Mössbauer Emission Spectra of Impurity ⁵⁷Cobalt in a Halide Matrix

Abstract

The Mossbauer emission spectra of 6 7 C~ in low concentrations in KF, NaCl, NaF, LiF, and MgFB, and the effects of doping NaF and UF with La*+ ions are reported. The monovalent halides all give similar spectra showing a broad single line or a doublet at 2.19mm/s and two overlapping doublets at 0.46 and 0.19 mm/s (w.r.t. metallic iron), although relative intensities vary. Previous Mossbauer and EPR spectroscopic data on these systems are reviewed briefly, and qualitative conclusions drawn on the chemistry of such systems.Es wird uber die MoBbaueremissionsspektren geringer Konzentrationen von 57cO in KF, NaCl, NaF, LiF und MgFB und uber den EinfluB einer Dotierung des NaF und LiF mit Laa+-Ionen berichtet. Ale monovalenten Halogenide zeigen iihnliche Spektren mit einer breiten einfachen Linie oder einem Dublett bei 2,19 mm/s und zwei sich uberlappende Dubletts bei 0,46 und 0,19 mm/s, wobei die relativen Intensititen nicht gleich sind. Friihere Ergebnisse der MoBbauer-und EPR-Spektroskopie dieser Systeme werden herangezogen und qualitative SchluBfolgerungen uber das chemische Verhalten derartiger Systeme erhalten.

57Fe Emission Mössbauer Study of the 57Co Electron Capture After-Effects in 57Co: KCoF3 and 57Co:KNiF3

“…Although the ionic character is known to be very important, the present values are significantly larger than the upper limits so far recorded, which are ranging between 1.40 and 1.50 mm-s -1 in 57 Fe : CaF 2 [18][19][20], 57 Co: CaF 2 [19], 57 Fe:CdF 2 [21], 57 Co : RbCaF 3 [22] and S7 Co:MgF 2 [23].…”

“…The more compact lattice of the Ni compound results in a significant increase of the Madelung potential (22.2 eV), which is found to be very similar to that in MgF 2 (22.3 eV [19]), where 82% Fe 3+ has been reported [15], although the latter result has given rise to some controversy [19,23]. From a general analysis of the experimental data presented in Table 3 for fluorinated compounds with related crystal structures, it can be concluded that thermodynamic and steric factors are both important in determining the distribution of nucleogenic Fe species.…”

Hot Atom Chemistry 1976

“…When 57 Co is introduced into monovalent halides (LiF, NaF ... ), most iron is in the Fe 3+ state in octahedral and tetrahedral sites; in the divalent MgF2 host, a large amount of Fe 2+ appears in a substitutional site; a Fe + line is also observed. More generally, the state of iron depends on the stoichiometry of the host, on the ionic radii which determine the size of the available sites and on defects arising from the preparation method and impurities [70].…”