The preparation and high-frequency electromagnetic properties of ferrimagnetic bisphthalonitrile-Fe3O4 core-shell hollow microspheres

Compared with traditional pure Fe3O4 nanoparticles, the hollow microspheres exhibited very strong magnetism due to their special structures. The saturation magnetization and coercivity of the ferrimagnetic hollow microspheres were 103.9 emu g−1 and 161.6 Oe, respectively. The electromagnetic properties of hybrids showed cooperative nonlinear magnetic and dielectric resonance in Ku-band. Moreover, the hybrid hollow microspheres also showed electromagnetic shielding characteristics in Ku-band. Three nesting reflection loss peaks can be seen around 13.0, 16.0 and 17.3 GHz. A minimum reflection loss of −38.5 dB was reached at 17.3 GHz with an absorber thickness of 4.2 mm.