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In this work, we report the fabrication of a high performance multi-layer varistor (MLV) via water based tape casting method using novel compositions of nanomaterials. Bi 2 O 3 , CaO and Co 3 O 4 doped ZnO nanopowders were prepared by solution combustion synthesis (SCS) route, calcined at different temperatures (550, 650, 750 and 850 °C) and characterized by TEM, XRD, SEM and AFM. The nanopowder (crystallite size ~30 nm) calcined at 650 °C for 1 h was used as the starting material for MLV fabrication. Compositions of the slurry containing doped ZnO nanopowders, binder and plasticizer in water solvent were optimized for the fabrication of thick film. The rheological properties of the slurries having different solid loadings were analysed and thick films of various thicknesses (50–500 µm) were prepared by varying the feeding rate of tape casting. The film roughness of 38.3 nm for the thick film made from 40 wt% solid slurry was found to be superior compared to other samples due to the presence of reduced crack and shrinkage. MLV fired at 950 °C for 1.5 h exhibited a coefficient of nonlinearity of 18 and breakdown voltage of 291.5 V that yields superior properties compared to commercial MLVs. [ABSTRACT FROM AUTHOR]

Conjugated polymer-layered filler nanocomposites have received extensive interest as multifunctional materials in various futuristic applications. In this study, the effect of graphene oxide (GO) particle size on the synthesis, optical, and electrochemical properties of in situ prepared graphene oxide (GO)-poly(3-hexylthiophene) (P3HT) nanocomposites have been studied. The intercalation of GO with P3HT is inferred from shifting and broadening of the characteristic D- and G-bands of GO in Raman spectra and also the vibrational frequencies in FTIR. This interaction is further confirmed from increase of the optical band gap and the ellipsometry data. The UV-visible absorption maximum ( λmax) of P3HT decreases from 438 to 418 nm in the nanocomposite owing to ionic interactions between GO and the polymer causing a decrease of the polymer conjugation length. Compared to the homopolymer, the emission maximum of the composite is broadened and enhanced in intensity with 10 wt% GO but emission quenching is observed with GO nanoparticles. The evidence of polymer intercalation was also deduced from the determination of the basal spacing and unit cell dimensions of GO, using X-ray diffraction data. Morphological studies using field emission scanning electron microscopy suggest that the crystalline rod-like structures observed in the homopolymer have changed to more amorphous, flaky, and porous structures. The cyclic voltammetry studies show an increase in current with increasing GO content in the porous nanocomposites. POLYM. COMPOS., 38:852-862, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]