Magnetic and microwave absorption properties in 2.6–18 GHz of A-site or B-site substituted BaFe₁₂O₁₉ ceramics

The A-site substituted (20 mol% Sr²⁺ and Ca²⁺) and B-site substituted (20 mol% Co³⁺ and Mn³⁺) M-type BaFe₁₂O₁₉ (BFO) ceramics were synthesized and the magnetic properties and microwave absorption were investigated. The A-site substitution by Ca²⁺ or B-site substitution by Co³⁺ can effectively modify the magnetic properties of the M-type BFO. The B-site dopant suppresses the complex permittivity more greatly than A-site ones and substitution of Co³⁺ at B-site changes the microwave permeability response to a resonate-like manner in 2.6–18 GHz. The A-site substitution is more effective on the enhancement of peak absorption whilst B-site substitution is more effective on the enhancement of absorption bandwidth. A wide bandwidth of reflection loss (RL) value below − 5 dB (> 70% microwave absorption) of the BaFe_11.8Mn_0.2O₁₉ ceramic is obtained in 3.6–18 GHz and the minimum RL of − 18.5 dB is obtained at 7.2 GHz with a thickness of 2.5 mm.