Structural, morphological and magnetic properties of MFe2O4 (M = Mg, Zn and Ni) synthesized by solid state reaction

Abstract MFe 2 O 4 (M = Mg, Zn and Ni) were synthesized by solid state reaction. In order to study the structural, morphological and magnetic properties, the samples were characterized using X-ray diffraction with Rietveld refinement, scanning electron microscopy, infrared spectroscopy, Mössbauer spectroscopy and magnetic measurements. In the XRD patterns, all the diffraction peaks were related to the crystallographic planes of the spinel structure. The Rietveld refinements of the XRD patterns indicate lattice parameters of 8.383 Å, 8.447 Å and 8.341 Å for MgFe 2 O 4 , ZnFe 2 O 4 and NiFe 2 O 4 , respectively. The SEM micrographs consist of agglomerates of particles with micrometric sizes and irregular shapes. The quantitative analysis of the SEM micrographs indicates average particle diameters in the ranges 0.51–2.85 µm, 0.50–4.37 µm and 0.16–1.72 µm for MgFe 2 O 4 , ZnFe 2 O 4 and NiFe 2 O 4 , respectively. The IR spectra consist of two main absorption bands related to the stretching vibrations of the bonds X-O (X = Mg, Fe, Zn and Ni) at tetrahedral (A) and octahedral [B] sites of the spinel structure. The Mössbauer spectra of MgFe 2 O 4 and NiFe 2 O 4 were fitted by introducing sextets related to Fe 3+ cations at tetrahedral (A) and octahedral [B] sites of the spinel structure. In the case of MgFe 2 O 4 , the hyperfine parameters of the tetrahedral sextet were δ = 0.27 mm/s and B = 46.4 T, while for the octahedral sextets, the values were δ = 0.33 mm/s and magnetic hyperfine fields (B) in the range 44.0–49.7 T. In the case of NiFe 2 O 4 , the hyperfine parameters of the tetrahedral sextet were δ = 0.25 mm/s and B = 49.0 T, while for the octahedral sextet, the values were δ = 0.36 mm/s and B = 52.3 T. The Mössbauer spectrum of ZnFe 2 O 4 was fitted by introducing one doublet with hyperfine parameters δ = 0.36 mm/s and Δ EQ = 0.34 mm/s. The hysteresis loops have S-shaped geometric forms, high saturation magnetization values and low coercive magnetic field values. NiFe 2 O 4 and MgFe 2 O 4 exhibit ferrimagnetic behavior at room temperature, with saturation magnetization values of 55.40 emu/g and 24.47 emu/g, respectively. ZnFe 2 O 4 predominantly exhibits paramagnetic behavior under the same conditions.