Nonlinear Conductive Characteristics of ZnO-Coated Graphene Nanoplatelets-Carbon Nanotubes/Epoxy Resin Composites

With the increasing threats arising from the electromagnetic environment, polymeric composites which could exhibit nonlinear conductive characteristics are highly required in the protection of electronic devices against overvoltage. In this research, ZnO nanoparticles are coated onto graphene nanoplatelets (GNPs)-carbon nanotubes (CNTs) hybrid, and then it is embedded in epoxy resin (ER) matrix via solution blending. Based on the characterization results, CNTs are well dispersed across the GNPs which prevent the restacking of GNPs and CNTs. At the same time, ZnO nanoparticles are well-bonded to the surfaces of GNPs-CNTs hybrid. During repeated conductive characteristic measurements, GNPs-CNTs-ZnO/ER composite is able to demonstrate distinctly reversible nonlinear conductive behavior, with high nonlinear coefficients. Especially, the filler content in GNPs-CNTs-ZnO/ER composite is only 12.5% of that in GNPs-ZnO/ER composite reported in our previous work. Moreover, it is shown that the nonlinear coefficients and switching threshold voltage can be modified by controlling the weight ratios of GNPs, CNTs, and ZnO. Finally, the samples with 1:1 weight ratio of GO to MWCNTs (A-6.67 and A-10) exhibit the best reversible nonlinear conductive behavior.

Reversible Nonlinear I-V Behavior of ZnO-Decorated Graphene Nanoplatelets/Epoxy Resin Composites

With the more serious threats from complex electromagnetic environments, composites composed of conductive or semiconductive fillers and polymeric matrices could exhibit excellent nonlinear I-V characteristics, and have drawn significant attention in the field of overvoltage protection. In this research, graphene nanoplatelets (GNPs) are decorated by ZnO and mixed into an epoxy resin (ER) matrix via solution blending to prepare composites. A characterization analysis and the I-V measurement results of the GNPs/ER composites indicate that ZnO nanoparticles are well bonded with GNPs and exhibit obvious nonlinear I-V behavior under proper applied voltage with high nonlinear coefficients. The switching threshold voltage and nonlinear coefficients could be controlled by adjusting the weight ratio of GNPs and ZnO of the filler. Moreover, compared with the poor recoverability of pure GNP-filled ER in previous research, the GNP-ZnO/ER composites exhibited excellent reversibility of nonlinear I-V behavior under multiple repetitive I-V measurements. And compared with different composites, the sample with a 1:8 weight ratio of GO to Zn(Ac)2 presents the smallest variation of switching threshold voltage at 158 V, with a standard deviation of 1.27% from among 20 measurements, which indicates the best reversibility. Finally, the conducting mechanism of the reversible nonlinear I-V characteristic is investigated and analyzed.

Conductive switching behavior of epoxy resin/micron-aluminum particles composites

Epoxy resin (ER)/micron-aluminum particles (MP) composites with different filling concentration of spherical particles were fabricated. The nonlinear conductive behavior of ER/MP composites under increasing applied voltage using the improved V-I method was investigated. Under sufficient high intensity applied constant voltage, the obvious conductive switching behavior of samples with volume fraction 12.7%, 16.9% and 18.9% was found. The conductivity of ER/MP composites increase up to 3–4 orders of magnitude when the conductor-insulator transition occurs. The switching threshold voltage decreases with the increase of volume fraction of MP in the composites. The results show that the ER/MP composites with conductive switching properties are of great potential application in electromagnetic protection of electron devices and systems.

Synthesis of Methyl Methacrylate/Acrylic Acid/N, N’-4, 4’-Diphenylmethane-bismaleimide Copolymer and its Electricity Storage Characteristics

Methyl Methacrylate (MMA)/acrylic acid (AA)/N,N’-4,4’-Diphenylmethane-bismaleimide (BMI) copolymer was synthesized by free radical polymerization. The copolymer was characterized by the Fourier Transform Infrared (FTIR), and the memory characteristic of the device was investigated by current-voltage (I-V) test. The structure of the memory device which is based on MMA/AA/BMI copolymer was sandwich, the bottom electrode was indiumtin oxide (ITO) and the top electrode was Al. The ON/OFF current ratio of the ITO/(MMA/AA/BMI copolymer)/Al memory device is ≥1×102 and the switching threshold voltage is about 1.8v.

Synthesis of tetranitro-oxacalix[4]arene with oligoheteroacene groups and its nonvolatile ternary memory performance

Memory devices based on 4N4OPz exhibit excellent ternary memory behavior with high ON2/ON1/OFF current ratios and low switching threshold voltage.

Synthesis and Resistive Switching Characteristics of Ethyl Methacrylate /N, N'-4, 4'-Diphenylmethane-Bismaleimide Copolymer

The Ethyl Methacrylate (EMA)/N, N-4, 4-Diphenylmethane-bismaleimide (BMI) copolymer was synthesized by the conventional free radical polymerization. The resulting copolymer was fully characterized by FTIR, TG, DSC and the film exhibited excellent film-forming property, high thermal and dimensional stability. The devices based on EMA/ BMI copolymer possess a sandwich structure comprising bottom indiumtin oxide (ITO) electrode and top Ag electrode. The as-fabricated device exhibits the nonvolatile rewritable flash type memory characteristics. The ITO/(EMA/BMI copolymer)/Ag memory device also demonstrates ON/OFF-current ratio of about 1 × 102 and lower switching threshold voltage of about 0.98V.

Electrical Switching in Thin Films of Nandi Flame Seed Cuticles

Current-voltage () characteristics of Nandi flame seed cuticles (NFSCs) have been studied as a function of irradiation, annealing, and poling temperature. The cuticles showed memory and threshold switching. Threshold voltage was about 5 V which is almost five times higher than observed in synthetic polymers. The threshold voltage increased to 6–8 V after irradiation and annealing depending on the duration of annealing or irradiation. After switching, conductivity increased by an order of . In reverse bias, increase of current was observed and the memory hysteresis loop was at higher conductivity than at the time of switching. Switching effect was minimized at a poling temperature of 370 K. Formation of semiquinones and quinoid radicals from phenolic compounds may have contributed to electrical switching and hysteresis effect.