Effect of sintering temperature on structural and magnetic properties of Ni_0.5-xMn_xZn_0.5Fe₂O₄ ferrites

The electromagnetic properties of spinel ferrites (AB₂O₄) are controlled by the particle/grain size, microstructure, heat treatment (during synthesis), and cation distribution-rearrangements (during sintering) among the tetrahedral [A] and octahedral [B] interstices in the cubic lattice. Here, we are reporting the effect of sintering temperatures on the microstructure, magnetic properties of Ni_0.5-xMn_xZn_0.5Fe₂O₄ (0.0 < x < 0.5) ferrites processed using the fumarato hydrazinate precursor combustion method and sintered at sintered at 1100 °C, 1150 °C, 1200 °C, and 1250 °C. Mössbauer spectra of Ni_0.5-xMn_xZn_0.5Fe₂O₄ (x = 0-0.5) sintered at 1100 °C and 1200 °C have been recorded at room temperature. For x > 0.2 compositions, the Mössbauer spectra indicate that the samples have ferrimagnetic nature (sextets) with a paramagnetic doublet. Area of doublet found to be increased with increasing the Mn-content. It is concluded that Mn is in the mixed valence states (3+ and 2+) in these series of samples