Dielectric and conductivity behaviors of nano ZnO doped polyvinyl alcohol (PVA) composites for various concentrations of dopant were investigated using impedance spectroscopy for a wide range of temperatures (303 K–423 K) and frequencies (5 Hz–30 MHZ). The dielectric properties of host polymer matrix have been improved by the addition of nano ZnO and are found to be highly temperature dependent. Anomalous dielectric behavior was observed in the frequency range of 2.5 MHz–5 MHz. Increase in dielectric permittivity and dielectric loss was observed with respect to temperature. The Cole-Cole plot could be modeled by low resistance regions in a high resistance matrix and the lowest resistance was observed for the 10 mol. % films. The imaginary part of the electric modulus showed asymmetric peaks with the relaxation following Debye nature below and non-Debye nature above the peaks. The ac conductivity is found to obey Jonscher's power law, whereas the variation of dc conductivity with temperature was found to follow Arrhenius behavior. Two different activation energy values were obtained from Arrhenius plot indicating that two conduction mechanisms are involved in the composite films. Fitting the ac conductivity data to Jonscher's law indicates that large polaron assisted tunneling is the most likely conduction mechanism in the composites. Maximum conductivity is observed at 423 K for all the samples and it is optimum for 10 mol. % ZnO doped PVA composite film. Significant increase in dc and ac conductivities in these composite films makes them a potential candidate for application in electronic devices.

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PVA–CeO2 nanocomposite films were synthesized by solution casting method and exhibit tape like nanoribbon structure in the 25 wt% CeO2 films. The 2.5 wt% and 25 wt% CeO2 films are suitable for UV filters while the 2.5 wt% film shows highest photoluminescence.

Bulk Ge 17 Te 83−x Tl x glasses (0 ≤ x ≤ 13), have been found to exhibit memory type electrical switching. The switching voltages (also known as threshold voltage -V th ) of Ge 17 Te 83−x Tl x glasses are found to decrease with increasing thallium content. The rate of decrease of V th is greater at lower concentrations and V th falls at a slower rate for higher thallium concentrations (x ≥ 6). The addition of thallium to the Ge-Te network fragments the covalent network and introduces ionic nature to it; the reduction in network connectivity leads to the decrease in switching voltages with thallium content. The decrease in the glass transition temperatures of Ge 17 Te 83−x Tl x glasses with increasing thallium concentration supports the idea of decrease in network connectivity with Tl addition. The more metallic nature of Tl also contributes to the observed reduction in the switching voltages of Ge 17 Te 83−x Tl x glasses with Tl content. Further, there is an interesting correlation seen between the threshold voltage V th and the average bond energy, as a function of Tl content. In addition, the switching voltages of Ge 17 Te 83−x Tl x glasses have been found to decrease with sample thickness almost linearly. The set-reset studies indicate that the Ge 17 Te 81 Tl 2 sample can be switched for more than 10 cycles, whereas other glasses could not be reset beyond two switching cycles.

Gd 2 O 3 nanoparticles synthesized by solution combustion method were used to prepare PVA-Gd 2 O 3 nanocomposite films of varying concentrations (2 wt%-6 wt% of filler) by solution casting method. Being a rare earth oxide, gadolinium oxide was expected to exhibit good photoluminescence and the nanocomposite was expected to be flexible as well. The Gd 2 O 3 nanoparticles prepared were found to be in cubic phase with an average size of 19 nm. Raman spectra showed the incorporation of Gd 2 O 3 into the polymer matrix. Scanning electron microscope images revealed that the particles were porous in nature, agglomerated and distributed evenly on the surface of the film in the form of clusters. The UV-Visible absorption spectra gave direct optical energy band gap value in the range 5.78-4.86 eV. Both band gap as well as the Urbach energy are seen to decrease with increasing concentration of the dopant. Four prominent photoluminescence peaks were observed in all the three composite films in the UV region (318 nm), deep blue region (396 nm), blue region (477 nm) and green region (553 nm). The color purity of the films using CIE coordinates was found to be the highest, 82.81%, in the 2 wt% film making this film a promising material for blue OLED's and blue flexible screens.