Improved Electrical Properties of Strontium Hexaferrite Nanoparticles by Co²⁺ Substitutions

In this work, the sol-gel route was employed to synthesize a series of Co²⁺-substituted strontium hexaferrite nanoparticles (Sr_1- Co Fe₁₂O₁₉, x = 0.0-0.50) to study the effect of cobalt ions doping on the magnetic, electrical, and structural properties of the nanoparticles. The structural analysis of the synthesized nanoparticles, performed by X-ray diffraction, showed the formation of a hexagonal structure having no secondary phases. The morphological analysis, performed through scanning electron microscopy, revealed spherical shaped nanoparticles with uniform distribution. Fourier transform infrared spectra demonstrated two consistent absorption bands indicating the intrinsic stretching vibrations around 600 and 400 cm^-1 for tetrahedral and octahedral sites, respectively. It was observed through VSM that with cobalt addition, the saturation magnetization increased and the coercivity decreased. Also, a typical decreasing trend of DC electrical resistivity with increasing temperature measured by a two-probe method confirmed the semiconducting behavior of the synthesized samples. An impedance analyzer was used for the dielectric measurements at room temperature against the alternating frequency range of 250 Hz to 5 MHz, and it was found that the dielectric constant decreased with the increase in cobalt content, suggesting that the doped nanomaterials can be used for microwave absorption, electronics, telecommunication, and other high-frequency applications.