the effects of multiwall carbon nanotubes on the electrical characteristics of zno-based composites

In this experimental work, the effects of multiwall carbon nanotubes (mwcnts) on electrical characteristics of zinc oxide–mwcnt–high-density polyethylene composite varistors have been investigated. all the samples were made at the temperature of 130 °c and pressure of 60 mpa by the hot-press method. results show that increasing zinc oxide content in the mixture increases breakdown voltage up to 170 v, where the highest nonlinear coefficient (α ~ 13) corresponds to the samples with 95 wt% of zno. results with regard to the effects of mwcnt as an additive reveal that increasing its content from 1 to 2.5% in the composites, the breakdown voltage decreases to 50 v, but the highest nonlinear coefficient (~ 14) corresponds to the sample with 1.5% of mwcnt content. it is also revealed that, heat treatment of the sample at a constant temperature of 135 °c and different time intervals from 2 to 10 h, the sample with 6 h annealing time shows maximum breakdown voltages (vb = 140 v) with the highest nonlinear coefficient (~ 14). investigation of the potential barrier height of samples shows a complete consistency with the breakdown voltage variations. the results have been justified regarding xrd patterns and sem micrographs of samples.