Enhanced X-band absorption and shielding performance of Gd-substituted barium hexaferrite

Gd- substituted barium hexaferrite has been synthesized by solid-state ceramic method to explore its X-band (8.2 – 12.4 GHz) absorption and shielding performance. The structural, magnetic, and microwave properties of the synthesized hexaferrite were studied by X-ray diffraction (XRD), micro-Raman spectroscopy, field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), and vector network analyzer (VNA). XRD patterns confirmed the hexagonal magnetoplumbite phase formation in all samples. A noticeable red shift in the Raman spectra from 710 to 705 cm-1 and 323–327 cm-1 suggested the presence of Fe2+ ions at 4f1 tetrahedral and 12k octahedral sites, respectively. Microstructural studies on as-prepared samples confirm particle size reduction up to 1.86 µm with Gd substitution. A modest increase in magnetization and remanence value for 20% Gd was noted. Coercivity increased with substitution, whereas the anisotropy field and crystalline anisotropy constant reduced with Gd addition. An overall improvement in shielding efficiency and absorption was noted for Gd- substituted samples. A maximum average shielding efficiency of 16.47 dB and effective absorption of 99.99% was recorded for 10% Gd. Overall, microwave absorbance is improved up to 97% with Gd substitution, which suggests this material can also work as an absorber in microwave device applications.