⁵⁷Fe Mössbauer Spectroscopy of Zinc Ferrite Prepared by a Variety of Synthetic Methods

Abstract
Confirmation of the suggestion of B site Zn²⁺ in nanocrystalline ZnFe₂O₄ has been sought through X-ray diffraction, ⁵⁷Fe Mössbauer 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 Mössbauer 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 Mössbauer 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.