Mössbauer Effect inK3Fe(CN)6

A Mössbauer-effect study of the low-spin compound ${\mathrm{K}}_3$Fe${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_6$ has been carried out under a wide variety of conditions. In concentrated samples, the quadrupole splitting, linewidth, and isomer shift were measured as a function of temperature. The components of the electric-field-gradient tensor (EFG) were determined from the quadrupole peak area ratios of single-crystal absorbers at 20 and 300°K. The orientations of the $g$ tensor and EFG in the concentrated salt were also determined by experiments using large magnetic fields in single crystals at low temperatures. Paramagnetic hyperfine structure was found at low temperatures in samples of ${\mathrm{K}}_3$Fe${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_6$ diluted in the diamagnetic ${\mathrm{K}}_3$Co${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_6$. The theory of hyperfine interactions as applied to this case is reviewed, and the sensitivity of the Mössbauer spectrum to the relative directions of the $g$ tensor and cubic field are discussed. Spectra are calculated using two models based on ESR and susceptibility results, and one of these is found to be in good agreement with the data.