Nonlinear Current–Voltage Properties of Polymer Composite Doped With Calcium Copper Titanate Fibers.

Since the discovery of gigantic permittivity properties of CaCu3Ti4O12 (CCTO) ceramics, development of its polymer composites application in supercapacitors, varistors and switching devices has been extensively investigated. Here the one-dimensional (1D) nano-sized CCTO nanofibers were prepared and used as fillers to improve the varistor Characteristics of epoxy composite materials. An obvious varistor effect was observed in CCTO_nfs/epoxy composite. The mechanisms of this varistor effect were analyzed by scanning capacitance microscopy technology. The nonlinear coefficient (α) of CCTO_nfs/epoxy composite with 48 wt% filler loading is about 4.65, which is much higher than of 2.42 for a single CCTO nanofiber. The mechanisms for this discrepancy were analyzed by scanning capacitance microscopy technology. The results show that the nonlinear current density-electric filed (J-E) relationship of the epoxy composites is contributed by the synergistic effects of potential barriers established at interfaces, grain boundaries and the participation of oxygen vacancies in CCTO nanofibers. All these results presented here provide a new insight into the electrical properties of CCTO. The CCTO_nfs/epoxy composites should have good application prospects in polymer composite varistor. [ABSTRACT FROM AUTHOR]