Enhanced microwave absorption performance of Fe3O4/Cu composites with coexistence of nanospheres and nanorods

In this work, Fe3O4/Cu composites with both nanorods and nanospheres have been constructed by one-step hydrothermal method. With the decrease of Fe/Cu molar ratio, Cu2+ ions enter into the lattice of Fe3O4 and substituted for Fe2+/Fe3+ ions firstly, then part of Cu2+ ions start to be reduced to Cu metal at molar ratio of 27:3. The samples only possess nanospheres with molar ratio of 30:0-27:3, while nanorods emerge and particle size of nanospheres reduces simultaneously with the ratio reaching to 25:5-23:7. Finally, contributed by nature resonance loss of Fe3O4, high conductivity loss of Cu, interfacial polarization between heterogeneous Fe3O4 and Cu as well as the coexistence of nanospheres and nanorods, the composite with Fe/Cu molar ratio of 25:5 shows RLmin of -53.43 dB and broad bandwidth (RL < -10 dB) of 5.84 GHz under the thin thickness of 1.9 mm over 2-18 GHz, which is superior than most of the existed Fe3O4-based microwave absorbers. (C) 2019 Elsevier B.V. All rights reserved.