Bandwidth Enhancement in Microwave Absorption of Binary Nanocomposite Ferrites Hollow Microfibers

The binary Ba_0.5Sr_0.5Fe₁₂O₁₉ (BSFO)/Ni_0.5Zn_0.5Fe₂O₄ (NZFO) nanocomposite ferrites hollow microfibers with high aspect ratios have been prepared by the gel precursor transformation process. These microfibers possess a high specific surface area about 45.2 m² g⁻¹, and a ratio of the hollow diameter to the fiber diameter estimated about 5/7. The binary nanocomposite ferrites are formed after the precursor calcined at 750 °C for 3 h. Their minimum reflection loss ( RL ) is −38.1 dB at 10.4 GHz. The microwave absorption bandwidth with RL value exceeding −20 dB covers the whole X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz). This enhancement in microwave absorption can be attributed to the exchange-coupling interaction, interfacial polarization and small size effect in nanocomposite hollow microfibers.