Tuning the nonlinear current-voltage behavior of CaCu3Ti4O12 ceramics by spark plasma sintering

CaCu3Ti4O12 ceramics have been prepared by the spark plasma sintering method. Our results indicate that facile fabrication process control can lead to an obvious microstructure change, and thus modulate the nonlinear current-voltage properties such as the breakdown electric field E-b (0.33-9.28 kV/cm) and nonlinear coefficient alpha (2.4-21.5). The SPS ceramics sintered at 900 degrees C for 5 min possess the largest Eb and a values, which are much higher than those of previous pure CaCu3Ti4O12 ceramics without dopants. It is suggested that the synergistic effects of enhanced barrier height, large activation energy at grain boundaries, and the evolution of microstructure lead to the superior J-E performance in present samples. These results reveal that the CaCu3Ti4O12 material has a promising prospect in the application as a varistor.