Enhanced microwave absorption of barium cobalt hexaferrite composite with improved bandwidth via c-plane alignment

Planar hexaferrite BaCo2Fe16O27 was prepared by a simple adsorbent combustion method. The BaCo2Fe16O27/paraffin composite with 45 vol% particles was subjected to a rotational orientation process in an external magnetic field, resulting in highly-oriented BaCo2Fe16O27 composite with an alignment degree of 0.88. The oriented composite showed higher permeability in both real and imaginary parts as compared to its random counterpart. Significant enhancement of microwave absorbing performance was obtained for the oriented composite in 8-18 GHz due to the enhanced impedance matching and magnetic loss, displaying much stronger absorption and greater bandwidth (≤−10 dB) than the random composite. Moreover, a thinner matching thickness can be achieved for a given matching frequency through the alignment of easy magnetization planes. The results showed that the c-plane alignment process holds promises for rational design of lightweight magnetic absorbers with planar anisotropy.