Magnetic ordering in Mg-Zn ferrites

The magnetic ordering of a series of magnesium-zinc ferrite, Zn_0.3Mg_xFe_2.7-xO_4±δ (0.5≤x≤1.1; 0≤δ≤0.2) has been investigated using Mössbauer measurements in the temperature range 295-620 K. The samples were found to be magnetic at room temperature with a hyperfine field at each site which increases with iron content. The Curie temperature was also observed to increase in a similar manner. The slope of this increase for B_hf and T_c is steeper for x≤0.6 than x≥0.7. It has also been observed that Mg²⁺ substitution by Zn²⁺ in MgFe₂O₄ affects the magnetic ordering and the internal hyperfine field. The Curie temperature decreases by ∼200 K and B_hf by ∼20%.