Hydrothermal solvothermal synthesis and microwave absorbing study of MCo ₂ O ₄ (M = Mn, Ni) microparticles

MCo2O4 (M = Mn,Ni) microparticles were synthesised by a simple hydrothermal solvothermal method. The samples were characterised by X-ray diffraction, X-ray energy dispersive spectroscopy and scanning electron microscopy, which showed that MnCo2O4 microparticles with spherical particles aggregated by a large number of small cubes and cubic shaped NiCo2O4 microcubes were obtained. The microwave absorption properties of these products were systematically investigated by vector network analysis. Results indicated that the minimum reflection loss value of MnCo2O4 microparticles was −26.34 dB at 11.04 GHz with the absorber thickness of 2.5 mm, which was much lower than that of NiCo2O4 microcubes with the same absorber thickness. The possible mechanism was analysed, indicating that the geometry and size of MCo2O4 (M = Mn,Ni) microparticles played a key role in microwave absorption.