The Sr0.5Ba0.5ScxFe12–xO19(SrBaSc)/NiFe2O4(NiFe) hard–soft nanocomposites (NCs) are synthesized by in situ sol–gel route. Impact of Sc3+ doping on their structure, morphology, and magnetic properties are examined. X‐ray diffraction confirms the coexistence of SrBaSc and NiFe phases without any impurity. Morphology of NCs reveals a cluster of hexagonal plate decorated by spherical grains. Magnetic characteristics of the NCs are examined by using a vibration sample magnetometer at room temperature and 10 K. The x = 0.000 sample shows some kinks in their M–H loops and the occurrence of two peaks in dM/dH(H). All the NCs with Sc3+ exhibit smooth shapes of M–H curves with single peak, revealing the complete and perfect exchange coupling behavior. The diverse magnetic parameters at both temperatures are determined. The values of saturation and remanent magnetizations are decreasing with the Sc content increase. The intensive electromagnetic absorption is observed in all the samples. Reflection loss (RL) of more than ‐18 dB is observed above 3 GHz. Strong coupling between Sc concentration and amplitude–frequency characteristics of the RL can be used for developing of the functional media for high‐frequency devices and will open broad perspectives for practical application in radar‐absorbing technology and electromagnetic compatibility.

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Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.