Synthesis, characterization, dielectric and magnetic properties of substituted Y-type hexaferrites

Fabrication of a series of zinc–strontium hexaferrites, Sr₂Zn_2−xMn_xFe_12−yHo_yO₂₂ (x = 0.0–1.0, y = 0.0–0.1) was carries out by chemical co-precipitation route with the aim to enhance the saturation magnetization and coercivity and decrease the resistivity to make the materials applicable for recording media of high-density applications. The synthesized hexaferrites were interpreted by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The results of XRD investigation certify the single magnetoplumbite phase formed in hexaferrites with regular crystallite particle size in the 31–38 nm range. Magnetic and dielectric properties of the hexaferrites were also observed. The dielectric parameters (dielectric loss also its tan loss and dielectric constant) were measured at ambient temperature and in 1.0 MHz to 3.0 GHz frequency range. These parameters of Mn–Ho-substituted Zn–Sr hexaferrites showed constant trend with frequency up to a certain value after that resonance sort of behavior was observed. In all the hexaferrites dielectric parameters initially decrease with frequency then become almost constant followed by resonance type behavior. The dielectric parameters of the synthesized samples decrease with dopant content initially but then increase up to maximum dopant level. The saturation magnetization (M_s) and remanence (M_r) increase as the dopant content increases due to magnetic substituents. The squareness ratios of all the nanomaterials synthesized in the present studies is less than 0.5. The coercivity (H_c) decreases by the substitution of Mn and Ho.