Field Grading Composite with Nonlinear Conductive Chains

Developing field grading materials with tunable electrical properties and superior mechanical properties is still an important problem. In this paper, composite with a chain-like structure of ZnO fillers is prepared by dielectrophoretic assembly. This novel field grading material presents an ultralow percolation threshold below 0.5 vol%, much less than 33 vol% in the traditional sense. Then, superior mechanical property is obtained: compared with traditional 35 vol% composites, tensile strength of 2 vol% chain-structured composites is increased from 4.5 MPa to 6.6 MPa, and elongation at break is increased from 77.5% to 162.5%. In addition, the chain-like structure of fillers works as an excellent conductive path, and switching field of this kind of field grading materials can be continuously tuned in the range of 580–1058 V/mm. This work is conducive to developing smart materials with capability to control the high electrical field self-adaptively.