Tuning the Properties of Novel Magnetic Oxide via Co–Bi Co-substitution Including Theoretical Background of Characterization Techniques

Sol–gel technique was adopted to synthesize Sr2−xCoxNi2Fe28−yBiyO46 (x = 0.00, 0.01, 0.02, 0.03, 0.04; y = 0.00, 0.05, 0.10, 0.15, 0.20) X-type hexa-ferrites. The lattice parameters were altered (“a” from 5.886 to 5.851 A and “b” from 84.637 to 84.672 A). The force constant was found to decrease with the substitution of Bi3+–Co2+. The dielectric constant decreased from 62.8 to 47.5, while the tangent loss increased from 0.06 to 0.13 within the frequency range of 1–1.5 GHz. The Cole–Cole plots symbolize the predominance of grains and grain-boundary resistance. The saturation magnetization was optimized, whereas coercivity was declined by the substitution of Bi3+–Co2+. The high values of the dielectric constant, high tangent loss, high saturation magnetization, and small values of coercivity revealed prospects of Bi3+–Co2+-substituted SrNi-based X-type hexa-ferrites as effective microwave absorbing materials or shielding materials for high frequency and multi-layer chip inductor materials.