Concentration dependent microwave absorption properties of the near-half-doped Ba_xSr_1-xFe₁₂O₁₉ hexaferrites

Barium-substituted M-type strontium hexaferrite having the chemical formula Ba_xSr_1-xFe₁₂O₁₉ (x = 0.4, 0.5, 0.6) was prepared using the solid-state reaction method. The X-ray Diffraction (XRD) peaks indicate that the materials have a single hexagonal phase. Scanning Electron Microscope (SEM) images show pores in the sample. The optical band gap slightly decreased from 1.77 eV to 1.72 eV with an increase in Ba concentration. High values for the dielectric constant and tangent loss are achieved for all the samples. Also, dielectric relaxation peaks were observed for all the samples. With an increase in Ba concentration, these relaxation peaks entirely shift to the higher frequency range. The magnetization measurement results reveal the nature of the M-H loop and an enhancement in the saturation magnetization ( M _s) with an increase in Ba concentration, while the coercivity remains unchanged. A minimum reflection loss of -38.4 dB was observed for the 0.4 Ba-substituted sample. The enhanced microwave absorption behaviour confirms the suitability of the prepared samples for electromagnetic shielding applications.