One-pot in situ molten salt synthesis of octahedral Fe3O4 for efficient microwave absorption application

Abstract

An easy, template-free one-pot method was carried out for mass preparation of microscale octahedral Fe₃O₄. Thermal decomposition and a flux-mediated method were combined by directly introducing ferric acetate into the molten flux, which is called an in situ molten salt method. The morphology, magnetic properties, electromagnetic parameters, and microwave absorption behaviors were characterized. With the right octahedral temperature (800 °C), the iron oxide has a strong electrostatic interaction with salt ions leading to a perfect octahedron morphology. The reflection loss of the sample annealed at 800 °C (named F-800) can reach −23.67 dB at a frequency of 15.24 GHz with only a 1.4 mm coating thickness. The strongest microwave absorption ability may be ascribed to the unique morphology, best impedance matching and large attenuation value.