Synthesis of magnetite nanostructures with complex morphologies and effect of these morphologies on magnetic and electromagnetic properties

Magnetite nanostructures with different morphologies (tube, urchin and dendrite) were synthesized via hydrothermal method and consequent reduction by hydrogen gas. Magnetization and electromagnetic (EM) properties were characterized. The results showed that the morphology of the nanostructures has a major role in the microwave magnetic and dielectric properties. The surface area and shape isotropy are the key factors for changes in EM properties of different morphologies. High surface area and anisotropic elongated shape of the dendritic nanostructures lead to their high microwave permittivity, whereas for urchin-like nanostructures their very high surface area resulted to low magnetization and microwave permeability. However, high permeability and low permittivity of tube-like nanostructures caused a good impedance matching and therefore the best EM absorption performance was observed in their case. The tube-like nanostructures produced a reflection loss peak value of about −40 dB at the frequency of 2 GHz with the layer thickness of 2 mm. The results showed that tube-like magnetite nanostructures are promising particles for efficient EM wave absorbing applications.