Microwave absorption of M-type hexaferrite Ba1-xCaxFe12O19 (x?≤?0.4) ceramics in 2.6–18?GHz

Ba_1-xCa_xFe₁₂O₁₉ (x?=?0.0, 0.1, 0.2, 0.3 and 0.4, BCFO) ceramics were prepared using high-temperature solid-state method and the effect of Ca²⁺ substitution was investigated. The grain size of BCFO ceramics sintered at 1250?°C for 2?h increases from 1?µm to 5?µm as Ca²⁺ added. The BCFO ceramics show a typical hard magnetic behavior with a maximum saturation magnetization (M_S) of 51.8?emu?g^?1 at x?=?0.2. The bandwidth of microwave reflection loss (RL) below ??10?dB (> 90.0% microwave absorption) is obtained in 7.60???9.8?GHz with the minimum RL ??30.8?dB at 8.5?GHz for x?=?0.2 (thickness 2.0?mm), which makes Ba_0.8Ca_0.2Fe₁₂O₁₉ ceramic a potential microwave absorption candidate.