Optimizing the structural and magnetic properties of Ba0.5Sr0.5Fe12O19 hexaferrite through Fe/(Sr-Ba) molar ratio

In the present study, M-type hexaferrite, Ba 0.5 Sr 0.5 Fe 12 O 19 , having Fe/(Sr-Ba) with molar ratios of 10, 11, and 12, was synthesised via the conventional solid-state reaction route. X-ray diffraction analysis confirms a single-phase hexagonal structure for the samples with molar ratios of 10 and 11. The sample with a molar ratio of 10 shows preferential grain growth along the (008) plane. The Mössbauer spectra show characteristic hyperfine splitting consistent with M-type hexaferrite. Optical absorption studies reveal a reduction in the optical band gap from 1.76 eV to 1.68 eV with decreasing molar ratio. Magnetic hysteresis measurements establish the soft ferrimagnetic nature of the materials, with a maximum saturation magnetization (M s ) of 99.34 emu/g observed for the sample with an 11-molar ratio. For the same composition, dielectric spectroscopy reveals a higher dielectric constant and dielectric loss. Meanwhile, the sample with a 12-molar ratio exhibits a significant enhancement in AC conductivity in the high-frequency region, with values increasing from 0.01 to 0.06 Ω -1 m -1 . The tunable, magnetic and dielectric properties of the as-synthesized M-type hexaferrites are key prerequisites that make them potential candidates for microwave absorbers and electromagnetic interference shielding applications. • Ba 0.5 Sr 0.5 Fe 12 O 19 hexaferrite samples with Fe/Sr–Ba molar ratios of 10, 11, and 12 were synthesized using the solid-state reaction method. • ●Single-phase formation was observed only in the samples with molar ratios of 10 and 11. • ●High dielectric constant and increased AC conductivity were observed in the sample with a 12-molar ratio. • ●High dielectric loss was observed in the 11-molar ratio sample, and a relaxation peak was at room temperature. • ●Improved magnetic behaviour, characterized by enhanced saturation magnetization and moderate coercivity, was observed in the samples with molar ratios of 10 and 11.