Abstract
The mixed zinc-magnesium ferrite chromate with composition Mg1−xZnxFeCrO4 (0.0 ≤ x ≤ 1.0) prepared by the conventional solid state double sintering ceramic technique were characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Mossbauer Spectroscopy (MS). The analysis of the X-ray pattern reveal that the samples crystalize in a single-phase cubic spinel structure and the lattice parameter increases linearly with increasing the Zn content. The SEM micrographs showed aggregates of stacked grains of about (0.2 ∼ 1.5 μm) in diameter. The 78 K Mossbauer spectrum of pure magnesium chromate shows an ordered magnetic structure with well resolved tetrahedral and octahedral sites. As Zn substitutes for Mg, the 78 K spectra started to show the presence of a paramagnetic component superimposed on broadened magnetic sextets. This behavior is attributed to the presence of superparamagnetic domains in the samples which will be discussed based on the weakening of A-B exchange interaction in ferrite lattice due to replacement of Fe3+ ions in tetrahedral sites by Zn2+ ions.
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