Effect of iron doping on the physical properties of europium manganites.

Polycrystalline samples of Eu_0.65Sr_0.35Fe_xMn_1−xO₃ (x = 0.1 and 0.5) were prepared by a solid state reaction technique. Preliminary microstructure and crystal structure of the compound at room temperature were studied using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) technique, respectively. It is found that with Fe doping, the grain size decreases, where the compound crystallizes in a single-phase orthorhombic structure. Both samples show three active Raman vibrational modes around 210, 488 and 610cm⁻¹. The substitution of Fe at the Mn site results in a slightly change in band positions of Raman spectra. The temperature variation of resistivity shows that these compounds have semiconductor behavior with activation energy 0.152 eV for x = 0.1 increases to the value 0.535 eV for x = 0.5. The frequency dependence of dielectric constant in these materials indicates that space charge polarization contributes significantly to their observed dielectric parameters.