Directed Growth and Microwave Absorption Property of Crossed ZnO Netlike Micro-/Nanostructures

Three-dimensional ZnO micro/nanorod networks were synthesized through the direct evaporation of metal zinc and graphite powders in Ar and O-2 at 910 degrees C without any catalyst. The micro/nanorod networks of as-synthesized ZnO were characterized by using scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction. The branches within one network show very regular cross orientation. The nanorods follow a growth direction [0001]. Mircrowave absorption properties of the ZnO netlike structures have been investigated in detail. The reflection loss (RL) of the netlike structures and nanotetrapod-shaped ZnO were calculated by using the relative complex permeability and permittivity. And the value of minimum RL for the composite with 50 vol % ZnO netlike structures is -37 dB at 6.2 GHz with a thickness of 4.0 mm. These results provide a wide insight for the netlike structure ZnO as desirable materials for the fabrication of micro/nanoscale functional electromagnetic shield devices.