Mossbauer Spectra and Crystallite Size Related Magnetic/Electric Properties of Yb Substituted Zn-Ferrite Nanoparticles
Perović, Marija M.
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Influence of thermal-annealing-controlled crystallite size on the magnetic/electric properties of Yb substituted Zn-ferrite nanoparticles (ZnFe1.95Yb0.05O4) is studied, and results of the analysis are presented here. Room temperature Mossbauer spectrum of as-prepared sample shows coexistence of the sextet/doublet structure due to the particle size distribution. The central doublet originating from superparamagnetic relaxations of smaller particles is found to constitute the major fraction of the Fe-57 signal in samples obtained by thermal annealing of as-prepared sample at various temperatures in 300 degrees C-800 degrees C range. The determined quadrupole splitting (QS) parameters are significantly higher compared to corresponding bulk counterpart value and display decreasing trend with the crystallite size increase. The similar to 29 nm-sample, obtained by annealing at 800 degrees C, shows bulk-like properties, both in terms of the observed QS value and observed distribution of iron ...ions within the spinel lattice. Electric resistivity has non-monotonic dependence on crystallite-size, which could be attributed to enhanced disorder in as-prepared material. Partial substitution of iron by ytterbium in Zn-ferrite is found to increase the dielectric constant.