The Mössbauer spectra produced by ${10}^{-4\mathrm{}}$-at.% ${\mathrm{Co}}^{57}$ and 0.5-at.% ${\mathrm{Fe}}^{57}$ doped in the normal spinels ${\mathrm{Co}}_3$${\mathrm{O}}_4$, Co${\mathrm{Rh}}_2$${\mathrm{O}}_4$, Co${\mathrm{Cr}}_2$${\mathrm{O}}_4$, Co${\mathrm{Mn}}_2$${\mathrm{O}}_4$, and Zn${\mathrm{Co}}_2$${\mathrm{O}}_4$ have been obtained. Based on properties of the spinel structure and on correlations with Mössbauer data from the natural-iron spinels, these spectra are interpreted in terms of the daughter and impurity iron being located on the tetrahedral and octahedral lattice sites. The charge state of the daughter iron is not always the same as that of the parent cobalt; instead, it is generally that of natural iron in the parallel spinel compounds ${\mathrm{Fe}}_3$${\mathrm{O}}_4$, Co${\mathrm{Fe}}_2$${\mathrm{O}}_4$, Fe${\mathrm{Co}}_2$${\mathrm{O}}_4$, Fe${\mathrm{Cr}}_2$${\mathrm{O}}_4$, Fe${\mathrm{Mn}}_2$${\mathrm{O}}_4$, and Zn${\mathrm{Fe}}_2$${\mathrm{O}}_4$. From this and other evidence, we propose that the daughter-iron's valence is determined primarily by the chemical bonding properties of iron (as distinct from cobalt) in the environment where it is created. Of the several models of spinel crystal chemistry, that of Goodenough and Loeb roughly accounts for our conclusions.

• Received 23 October 1973

DOI:https://doi.org/10.1103/PhysRevB.9.3658