Elucidation of microwave absorption mechanisms in Co–Ga substituted Ba–Sr hexaferrites in X-band

The tunable microwave absorbers are used to combat the electromagnetic pollution created by the development of high speed electronic devices. In the present paper, we report microwave absorption characteristics of M-type Ba_0.5Sr_0.5Co_xGa_xFe_12−2xO₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) hexagonal ferrite compositions prepared by using double sintering ceramic method. X-ray diffraction analysis of the prepared compositions revealed the formation of M-phase along with the minor traces of hematite in substituted compositions. The microwave absorption has been elucidated substantially through various mechanisms in the test frequency range from 8.2 to 12.4 GHz, which is still partially explored in literature. The substitution of Co²⁺ and Ga³⁺ ions enhances microwave absorption, bandwidth, decreases thickness and improves impedance matching. The hysteresis parameters also comply with the microwave absorption. The optimal reflection loss of − 29.74 dB is observed in the composition x = 0.2 at 8.28 GHz with 2.0 mm thickness. The investigated mechanisms of microwave absorption can be incorporated to optimize the absorption and design of the microwave absorbers.