Effect of iron doping on the physical properties of europium manganites

Polycrystalline samples of Eu0.65Sr0.35FexMn1−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 610 cm−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.

► Single-phase polycrystalline perovskites Eu0.65Sr0.35FexMn1−xO3 (x = 0.1 and 0.5) were synthesized by a solid state reaction technique. ► The microstructure study showed that the grain size decreases with increasing the iron concentration. ► The electrical resistivity decreased with increasing temperature and the conduction mechanism is thermally activated. ► The frequency dependence of the dielectric constant in these compounds indicates that space charge polarization contributes significantly to their observed dielectric parameters. ► An increase in the dielectric constants with increasing the iron content is observed and a decrease with changing the measuring frequency at room temperature.