OICC Press Journal of Theoretical and Applied Physics 2251-7235 14 4 2023 11 17 The effects of multiwall carbon nanotubes on the electrical characteristics of ZnO-based composites 10.1007/s40094-020-00389-y EN N. Asaadi Department of Condensed Matter Physics, Faculty of Physics, University of Tabriz, 29 Bahman Blvd., Imam St., Tabriz, Iran M. Parhizkar Department of Condensed Matter Physics, Faculty of Physics, University of Tabriz, 29 Bahman Blvd., Imam St., Tabriz, Iran 0000-0002-6847-6799 H. Bidadi Department of Condensed Matter Physics, Faculty of Physics, University of Tabriz, 29 Bahman Blvd., Imam St., Tabriz, Iran S. Mohammadi Aref Department of Condensed Matter Physics, Faculty of Physics, University of Tabriz, 29 Bahman Blvd., Imam St., Tabriz, Iran M. Ghafouri Department of Physics, Faculty of Physics, Shabestar Branch, Islamic Azad University, Shabestar, Iran Journal Article 2023 11 17 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 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.