No abstract

Different concentrations of metal chlorides/polyvinyl alcohol nanocomposites have been prepared by the typical solvent cast technique. The prepared samples were investigated by different techniques such as X‐ray diffraction, differential scanning calorimetry, and scanning electron microscope. DC and AC conductivities are examined at different temperatures and frequencies. An activation process was found in the DC conductivity versus temperature relation and the activation energy was calculated. The AC conductivity obeyed the ωS power law. The behavior of S with temperature was studied. Various dielectric parameters such as dielectric constant (ε′), dielectric loss (ε″) and loss tangent (tan δ) have been determined in the temperature range 303–443 K at different frequencies. The dielectric parameters were found to decrease with increasing frequency. The study of dielectric relaxation as a function of temperature at constant frequency shows two relaxation mechanisms. The optical band gaps and band tails were estimated from the measured absorption spectra. The applied photon energy found to affect the observed optical band gaps. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

No abstract

Subject classification: 72.20. Ee; 72.80.Ga; 72.80.Ng; S10.15 The dc conductivity and switching properties of glassy samples of the system (76V 2 O 5 -24P 2 O 5 ) 1--x (TeO 2 ) x (where x = 0.0, 0.02 and 0.1 mol%) are investigated in the temperature range 303-625 K. The activation energy of conduction DE s , the predominant phonon frequency n ph and the Debye temperature q D were deduced. A composition dependence of the samples has been found. Thickness and temperature dependence of the I-V characteristics of the samples have been studied showing switching at the turnover point (TOP) from high resistance state (off state) to the negative differential resistance state (NDRS). Measurements of the dissipated power P th , the threshold voltage V th and the threshold resistance R th were carried out at TOP for different thicknesses and temperatures of the samples. The activation energies DE v , DE r and DE p (caused by threshold voltage, current and power, respectively) at the turnover point are deduced for different thicknesses of the samples. Temperature and composition dependence of the conduction path temperature (T 0 ), rise in temperature of conduction path DT J , specific heat S, density of localized states N(E F ) and the hopping distance have been obtained. The results are interpreted in terms of both electrothermal and the small polaron model.

No abstract