A novel synthesis of porous Ba2Co2Mn1.2Fe10.8O22/carbon composites for high efficiency electromagnetic wave absorption

Designing an electromagnetic wave (EMW) absorbing material with ultra-wide effective absorption bandwidth (EAB) and low filling ratio is the key to solving the problem of electromagnetic pollution. In this study, the porous Ba 2 Co 2 Mn 1.2 Fe 10.8 O 22 /C (Mn-Co 2 Y/C) composites were prepared by radial freeze-drying method as well as high temperature carbonization process (400 °C, 500 °C, 600 °C, and 700 °C). The research results indicate that the sample annealed at 600 °C exhibits superior EMW absorption properties, achieving the widest EAB of 5.77 GHz at a thickness of 1.7 mm, which is attributed to the synergistic effect of multiple reflections of EMWs within microchannels of the samples and the interfacial polarization between Mn-Co 2 Y ferrite and C material. Samples prepared at 600 °C have the best impedance matching, which makes it easier for EMWs to enter the material, thus exhibiting better EMW absorption performance. The magnetic loss mainly originates from natural resonance at low frequencies and eddy current loss at high frequencies, and the dielectric loss stems from relaxation loss and conductivity loss.