Recoilless fraction of cobalt-doped magnetite

Hydrothermally-synthesized Fe3−xCoxO4 (x = 0-0.9) samples were analyzed by transmission Mössbauer spectroscopy in order to determine the recoilless fraction of the tetrahedral (A) and octahedral (B) sites as a function of the cobalt content x. Our results provided direct evidence for the presence of the Co substitution in the B sublattice, which was found to be accompanied by a systematic increase of the hyperfine field at these sites. The recoilless fractions of the two sublattices were determined using our recently-developed dual absorber method. The recoilless fraction of the tetrahedral sites is practically constant, while that of the octahedral sites steadily decreases with increasing the Co content. These results tend to suggest that only the iron lattice participates in the recoilless process.