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Abstract
Solid solution of spinel ferrite system, CuFe2O4 and Cu1-x ZnxFel.9Ga0.1,O4 with (0.0. x 0.5 in mole percent) are synthesized. XRD measurements confirm the presence of single-phase tetragonal structure with c/a>1 for CuFe2O4 and samples with (x=0.0 and 0.1). The tetragonal phase is attributed to the presence of the cooperative Jahn-Teller (Cu2+) ions in the octahedral B-¬site in the spinel lattice. Tetragonal-to-cubic transformation is occurred at the compositional parameter x 0.2.
The lattice parameter < a > determined for the cubic sample is found to decrease with increasing Zn content x. Crystallographic investigation from the step scan XRD of the sample with (x=0.3) reveals that Zn occupies the tetrahedral A-sites while Cu and Ga ions occupy the octahedral B-sites, and Fe ions distributes among A- and B-sites.
57Fe Mössbauer effect measurements at 293K for these compounds reveal super-paramagnetic phase for samples with (0.0 x 0.2). In contrast, at 12K the Mössbauer effect spectra for these materials show well ordered spectra where, the cation distribution and the hyperfine parameters are determined and discussed as a function of the compositional parameter x. Electrical conductivity measurements of these materials as a function or temperature and frequency revealed semiconducting behavior except CuFe2O4 sample, which has a metallic behavior at low frequency. While; at high frequency, semiconductor to metallic transition is occurred as temperature increases. The metallic behavior in this sample is attributed to the cation-cation interactions at B-site while, the semiconductor behavior in Cul-xZnxGa0.1Fe1.9O4 compounds is due to the cation-anion-cation interactions at the same site.