Fe-57 Mossbauer spectroscopy of zinc ferrite prepared by a variety of synthetic methods

Confirmation of the suggestion of B site Zn2+ in nanocrystalline ZnFe2O4 has been sought through X-ray diffraction, Fe-57 Mossbauer spectroscopy, magnetic susceptibility and TEM measurements on bulk and nanocrystalline samples prepared by different techniques. Measurements on bulk samples are in agreement with previously reported ones. Samples prepared at low temperature from solutions of salts exhibit broadened XRD patterns, susceptibilities 4-5 times that of bulk samples, broadened Mossbauer spectra and particle sizes between 5-20nm. Low-impact, ball-milled bulk samples exhibited properties similar to the low temperature, nanocrystalline samples. At 298K, the Mossbauer spectra exhibit no magnetic hyperfine splitting and no evidence for a significant proportion of A site Fe3+ ions. The unusually high susceptibilities appear to result mainly from the decreased particle size and not from profound changes in the cation distribution of a well-defined, spinel structure.