Effect of non-stoichiometry in lead hexaferrites on magnetic and dielectric properties

The effect of iron deficiency on the structural, electrical and magnetic properties of the nano PbFe12-xO19-δ (where x = 0.0, 0.25, 0.50, 0.75 and 1.0) hexaferrites prepared by sol-gel auto combustion and further processed by microwaves is presented. The structure studied using transmission electron microscope (TEM) showed hexagonal cylindrical particles with an average size of ∼20 nm. Selected area electron diffraction (SAED) reflected highly crystalline nature of these nanoparticles. From the dielectric characterizations ac-conductivity, dielectric constant and loss tangent are analysed for pure and modified PbFe12-xO19-δ hexaferrites. The magnetic analysis revealed the formation of single-domain structure. Saturation magnetization (MS) decreases from 63.2 (x = 0) to 38.2 (x = 1.0) emu/g with increasing the Fe ions deficiency. Room temperature Mössbauer spectra show five sextets for all compositions confirmed the single phase formation. The relative area of 12k (↑) site decreases and 4f2 (↓) increases drastically with increasing the Fe ions deficiency in Pb-hexaferrites.