Synthesis of hollow Fe3O4 particles via one-step solvothermal approach for microwave absorption materials: effect of reactant concentration, reaction temperature and reaction time

Hollow Fe3O4 particles with variable crystal sizes were synthesized by one-step solvothermal method for lightweight and efficient microwave absorber applications. The reactant concentration, reaction temperature and reaction time are three key factors for morphology control of the products and can further influence the microwave absorption properties. The diameters of as-prepared hollow magnetite particles ranged from 200 to 1000 nm, while the shell thickness differed from 35 to 280 nm. It is found that the microwave absorption properties are improved along with the increasing of the hollow structure size which depend on the reaction conditions. The sample prepared at 200 °C for 36 h exhibited an optimal reflection loss of − 55.14 dB at 11.76 GHz with the thickness of 2.07 mm, while possessing the broadest effective bandwidth reaching 4.72 GHz (5.6–10.32 GHz) at 2.49 mm. The excellent microwave absorbing properties of such materials can be attributed to the high magnetic loss and favorable impedance matching property.