Influence of Pb doping on structural, electrical and magnetic properties of Sr-hexaferrites

Sol–gel auto-ignition technique was used for the synthesis of Pb-doped strontium ferrites with compositions Sr1−xPbxFe12O19 (x = 0.00, 0.05, 0.10, 0.15, 0.20). Sintering of the samples at 800 °C for 2 h developed a stable hexagonal phase which was confirmed by X-ray diffraction analysis. Lattice parameters and unit cell volume were calculated utilizing the data received from this analysis and it was observed that their values were increased with increasing concentration of Pb doping. The Pb doping decreased the porosity making the ferrites samples more compact. A small increase in crystallite size, determined with the help of Scherrer’s formula, could be attributed to the substitution of Pb2+ having slightly larger ionic radius than that of Sr2+. Frequency and temperature dependent dielectric constant and dielectric tangent loss were determined for all the compositions, and it was observed that their values were decreased with the increase in frequency and increased slightly with the increase in temperature of the samples. The increase in Pb contents decreased dielectric constant and dielectric tangent loss that favors the use of materials in high frequency appliances. The magnetic properties of the samples were investigated, using a vibrating sample magnetometer and the results showed that the increasing ratio of diamagnetic Pb decreased saturation magnetization and remanence, and increased the coercivity that made the materials useful for the fabrication of devices which require hard magnetic properties.

► Highly phase pure Sr-hexaferrites were prepared by sol-gel auto-combustion route.
► Increased Pb-contents at Sr-sites decreased dielectric constant and tangent loss.
► Increased Pb-contents decreased saturation magnetization and increased coercivity.
► The samples were noted as suitable for recording media applications.