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

AbstractIn 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 ۱۳۰ °C and pressure of ۶۰ MPa by the hot-press method. Results show that increasing zinc oxide content in the mixture increases breakdown voltage up to ۱۷۰ V, where the highest nonlinear coefficient (α ~ ۱۳) corresponds to the samples with ۹۵ wt% of ZnO. Results with regard to the effects of MWCNT as an additive reveal that increasing its content from ۱ to ۲.۵% in the composites, the breakdown voltage decreases to ۵۰ V, but the highest nonlinear coefficient (~ ۱۴) corresponds to the sample with ۱.۵% of MWCNT content. It is also revealed that, heat treatment of the sample at a constant temperature of ۱۳۵ °C and different time intervals from ۲ to ۱۰ h, the sample with ۶ h annealing time shows maximum breakdown voltages (Vb = ۱۴۰ V) with the highest nonlinear coefficient (~ ۱۴). 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.

Keywords:

Multiwall carbon nanotube , ZnO , Composite varistor , Nonlinear coefficient