Preparation of rugby-shaped CoFe₂O₄ particles and their microwave absorbing properties

Porous rugby-shaped CoFe₂O₄ particles were synthesized using a vapor diffusion method in combination with calcination. The morphologies and structures of the as-prepared CoFe₂O₄ particles were characterized by field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and N₂ adsorption-desorption measurement. Results showed that uniform CoFe₂O₄ rugbies were about 1.1 μm in length and 500 nm in width at the widest point. Rugby-shaped CoFe₂O₄ nanoparticles were assembled by the layers of nanoparticles and exhibit porous structures. The magnetic and electromagnetic parameters were measured using a vibrating sample magnetometer and a vector network analyzer, respectively. The obtained rugby-shaped products exhibited a saturation magnetization of 73.4 emu g^-1 and a coercivity of 2218.7 Oe at room temperature. A minimum reflection loss of -34.1 dB was observed at 13.4 GHz for the sample with a thickness of 2.5 mm, and the effective absorption frequency (RL < -10 dB) ranged from 12.3 to 14.9 GHz, indicating the excellent microwave absorption performance of the novel products. The absorbing performance of the CoFe₂O₄ rugbies was better than that of the CoFe₂O₄ nanoparticles.