The Influence of Cation Substitution on the Magnetic Behaviour of Magnesium Ferrite
New polycrystalline specimens of the ferrites Mg1.5Fe1Si0.5O4, Mg1.5Fe1Ge0.5O4, Mg1.5Fe1Ti0.5O4 and Mg1.66Fe1Sb0.33O4 have been prepared and studied by nuclear gamma ray resonance technique, over a wide temperature range. All samples are monophasic spinel type ferrite with cubic symmetry. Mössbauer effect spectra of the composition containing Si4+ or Ge4+ show magnetic hyperfine splitting at room temperature, and Néel transition points are found around 750 and 570 K for the two compounds respectively. The spectrum of Mg1.5Fe1Ti0.5O4 is paramagnetic at 300 K while at 78 K shows a superposition of a broad six lines pattern and a central quadrupole doublet. The sample with pentavalent antimony exhibits a strong ferromagnetic relaxation at 78 K where it shows six broad lines with enhancement of the two inner lines as the temperature is risen. For all compositions the Mössbauer effect parameters are determined and cation distributions are deduced and its effect on the magnetic behaviour is discussed.
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