Effect of transition metal ion substitution on structural and magnetic properties of Eu2O3 sesquioxide system

Abstract

The effect of trivalent transition metal ion (Fe3+) substitution in Eu2O3 system has been carried out. The ceramic compounds of Eu2−xFexO3 (where x = 0–0.5) are prepared by solid-state reaction technique. The crystal symmetries of synthesized materials have been calculated from powder X-ray diffraction patterns through Rietveld refinement process. The Rietveld refinement confirms that the pure Eu2O3 compound exhibits multiphase structure (monoclinic and cubic) of space group (c 1 2/m 1) and (I a -3). The incorporation of Fe3+ ion in the rare earth site (Eu3+) leads with change of cubic crystal symmetry to orthorhombic multiphase (monoclinic and orthorhombic) of space group (c 1 2/m 1) and (p b n m). The field emission scanning electron microscopic images of the samples reveals the substitutional effect of transition metal ion with the increasing grain growth and grain boundaries. The energy dispersive analysis confirms the increasing concentration of Fe3+ ion in to the host Eu2O3 system. From the Raman spectra, it is observed that most of intense Raman resonance peaks are dully assigned with cubic phase Eu2O3 compound. Further, it is noticed that the major intensity Raman signal of Eu2O3 compound at 109 cm−1 assigned with Fg mode is goes on decreasing with respect to increasing concentration of Fe which evident the change of crystal structure from cubic phase to Orthoferrite phase in Eu2−xFexO3 compounds The diffused reflectance study confirms the semiconducting nature of all the prepared compounds. Magnetization analysis reveals that due to substitution of transition metal ion in rare earth site leads with decreasing trend of magnetic moment which is due to the fact of substituting lower ionic radii element (Fe3+) in non-magnetic Eu3+ ion leads with change in position of atoms in their crystal structure by variation in bond length and bond angles between RE–O and induces co-linearity in magnetic exchange interactions. Hence even the partial substitution of ferromagnetic Fe3+ ions in Eu3+ lattice site induces change in magnetic sub-lattices due to the variation in crystallographic position of atoms and results in paramagnetic ordering with lower magnetic moment than the parent compound.